INDOLE 3 CARBINOL, A NOVEL APPROACH TO CANCER TREATMENT

C. Deepa Nair, Toji Tom

National College of Pharmacy, Manassery, Calicut

Cite this: C. Deepa Nair, Toji Tom, "Indole 3 carbinol, a novel approach to cancer treatment", B. Pharm Projects and Review Articles, Vol. 1, pp. 234-298, 2006. (http://farmacists.blogspot.in/)

 

 

CANCER

    Cancer is a group of more than 100 diseases characterized by uncontrolled cellular growth, local tissue invasion, and distant metastasis. Cells that have undergone neoplastic transformation usually express cell surface antigens that may be of normal fetal type, may display other signs of apparent immaturity and may exhibit qualitative and quantitative chromosomal abnormalities, including various translocations and appearance of amplified gene sequence. A small subpopulation of cells within tumor can be described as tumor stem cells. Such cells can express clonogenic or colony forming capability. Tumor stem cells often have chromosome abnormalities. The invasive and metastatic processes as well as a series of metabolic abnormalities resulting from the cancer cause illness and eventual death of the patient unless the neoplasm can be eradicated with treatment.

 

    The role of the pharmacist in the management of the cancer patient can be very diverse. Through knowledge of antineoplastic drug pharmacology and pharmacokinetics is essential to prevent and manage many drug-induced toxicities. Provision of drug information is another critical role for oncology pharmacist. Experienced pharmacists are able to fulfill those roles to make valuable contribution to patient care in the oncology setting.

 

 

 

 

 

ETIOLOGY OF CANCER

 

Carcinogenesis:

 

    The mechanism by which cancer occur is incompletely understood. Current evidence supports the concept of carcinogenesis as a multistage process that is genetically regulated.

 

    The first step in the process is initiation, which require exposure of normal cells to carcinogenic substances. The carcinogens produce genetic damage, that if not repaired, result in irreversible cellular mutations. Chemical carcinogens, (particularly those in tobacco smoke) as well as azo dyes, aflatoxins, asbestos and benzene have been implicated in cancer induction in humans and animals. Certain herpes and papilloma group DNA virus have also been implicated as causative agents in animal cancers.

 

    During the second phase known as promotion, carcinogens or other factors alter the environment to favour the growth of the mutated cell population. The primary difference between promotion and initiation is that promotion is a reversible process. In fact because it is reversible, promotion phase may be the target of future chemo prevention strategies.

 

    The final stage of neoplastic growth called progression involves further genetic changes leading to increased cell proliferation. The critical elements of this phase include tumor invasion into local tissues and development of metastases.

 

    Substances that may act as carcinogens include chemical, physical, and biologic agents. Exposure to chemicals may occur by virtue of occupational and environmental means as well as life style habits the association of aniline dye exposure and bladder cancer is one such example. physical agents that act as carcinogens include ionizing radiation and ultraviolet light. These radiations include mutations by forming free radical that damage DNA and other cellular components. Viruses are biological agents that are associated with certain cancers. The Epstein-Barr virus is believed to be an important factor in the initiation of African Burkitt's lymphoma. All the previously mentioned carcinogens, as well as age, gender, diet, growth factors and chronic irritation, are among the factors considered to be promoters of carcinogenesis.

 

Genetic Basis:

 

    There are two major classes of genes involved in carcinogenesis: oncogenesis and tumor suppressor genes. Oncogenes develop from normal genes called proto-oncogenes and may have important roles in all phases of carcinogenesis. Genetic alteration of proto-oncogenes through point mutation, chromosomal rearrangement activates oncogene.

 

    Tumor-suppressor genes regulate and inhibit cellular growth and proliferation. Gene loss or mutation results in loss of control over normal cell growth. Two common examples of tumor-suppressor genes are retinoblastoma (Rb) and p53 genes.

 
DIAGNOSIS

 

The presenting signs and symptoms of vary widely and depend on type of cancer. The presentation in adult may include:

• Change in bowel or bladder habits
• A sore that doesn't heal
• Unusual bleeding or discharge
• Thickening or lump in breast or elsewhere
• Indigestion or difficulty in swallowing
• Obvious change in wart or mole
• Nagging cough or hoarseness

 

    The definitive diagnosis of cancer relies on procurement of a sample of tissue and its pathological assessment.

 

PATHOLOGY

Tumor characteristics

 

    Tumor may be either benign or malignant. Benign tumors are non-cancerous growths that are often encapsulated, localized. The benign tumor resembles cells from which they develop. These seldom metastasize and once removed, they rarely occur. In contrast malignant tumor invade and destroy the surrounding tissue. The cells of malignant tumor are genetically unstable and loss of normal cell architecture result in cells that are atypical of their tissues or cells of origin. These loose the ability to perform their usual function. This loss of structure and function is defined as anaplasia. Recurrences are common after removal or destruction of primary tumor.

 

Tumor Origin

    Tumor may arise from any of the four basic tissue types:

• Epithelial tissue
• Connective tissue
• Lymphoid tissue
• Nerve tissue

 
TREATMENT

 

Modalities of cancer treatment

 

    Four primary modalities employed are:

• surgery
• Radiation
• Chemotherapy
• Biological therapy

 

    Oldest is surgery. It is the treatment of choice for most solid tumors diagnosed in early stages. Although effective, surgery and radiation are local treatments. Because most patients with cancer have metastatic diseases, localized therapies often fail to completely eliminate the cancer. In addition systemic diseases such as leukaemia cancer treatment with a localized modality. Chemotherapy (including hormonal therapy) assesses the systemic circulation and can theoretically treat primary as well as any metastatic disease. Biological therapy also known as immunotherapy involves stimulating the host immune system to fight the cancer. Many of the agents of this category are naturally occurring cytokines, which have been produced with recombinant DNA technology. Eg: interferons (INFs) , interleukins (ILs)

    Management of most types of cancer involves the use of combined modalities.

 

PRINCIPLES OF CHEMOTHERAPY

 

    The modern era of cancer chemotherapy was born in 1941, when Goodman and Gilman first administered nitrogen mustard to patients with lymphoma. Since that time, numerous antineoplastic agents have been developed.

 

Response: The response to chemotherapy and other treatment modalities may be described as :

• Cure
• Complete response
• Partial response
• Stable disease
• Progression

 

 

Basic pharmacology of cancer chemotherapeutic drugs

 

    Agents used in cancer chemotherapy are commonly categorized by their mechanism of action or by their origin.

 

• Polyfunctional alkylating agents:

Cyclophosphamide, mechlorethamine

 

    These exert cytotoxic effects via transfer of their alkyl groups to various cellular constituents. These drugs react with chemically with sulph hydril, amino, hydroxyl, carboxyl and phosphate groups of other cellular nucleophiles as well. The general mechanism of action of these drugs involve intramolecular cyclization to form an ethylenimonium ion.

 

    Active alkylating agents have direct vesicant effects and can damage tissues at the sites of injection as well as produce systemic toxicity.

 

    Oral administration of alkylating agents agents have been developed using relatively less reactive alkylating drugs.

 

    All alkylating agent are cytotoxic, mutagenic, teratogenic, carcinogenic and myelosupressive. Resistance to these sgents can occur from increased DNA repair capabilities from decreased entry into or accelerated exit from cells from increased inactivation of the agents inside cells or from lack of cellular mechanism to result in cell death following DNA damage

 

• Antimetabolites:

 

    Neoplastic cells have a number of quantitative differences in metabolism from normal cells that render them more susceptible to a number of antimetabolites or structural analogues.

 

    The metabolic pathways that have this far proved to be most vulnerable to antimetabolites have been those related to nucleic acid and nucleotide synthesis in a number of instances where an enzyme is known to have a major effect on pathways leading to cell replication, inhibitors of the reaction it catalyzes have proved to be useful anticancer drugs. The principal drugs are: methotrexate, fluorouracil.

 

 

• Plant alkaloids:

 

    Vinblastine derived from Vinca rosea. Its mechanism of action involves depolymerisation of microtubules which are important part of cytoskeleton and mitotic spindle which result in mitotic arrest at metaphase, dissolution of mitotic spindle, and interference with chromosome segregation.

 

    Vincristine is also an alkaloid derivative of Vinca rosea. It has same mechanism of action as that of vinblastine and has a strikingly different spectrum of vinblastine and has a strikingly different spectrum of clinical activity and qualitatively different toxicities. Others of this group are vinorelbine, paclitaxel.

 

• Anti tumor antibiotics:

 

    Screening of microbial products has led to the discovery of a number of a number of growth inhibiting hormones that have proved to be clinically useful in cancer therapy. Many of these antibiotics bind to DNA through intercalation between specific bases and block the synthesis of RNA, DNA or both, cause DNA strand scission and interfere with cell replication. All of the anticancer antibiotics now being used in clinical practice are products of various strains of the soil microbe streptomycetes. These include the anthracyclines, dactinomycin, bleomycin and mitomycin.

 

    Anthracyclines isolated from Streptimyces peucetius var caesius, are among the most widely used cytotoxic anticancer anticancer drugs. Several other anthracycline analogs have entered clinical practice including idarubicin, epirubicin and mitoxantrone.

 

 

 

 

 

 

• Hormonal agents:

 

Steroidal hormones and antisteroidal drugs

 

    Sex hormones and several other hormones are employed in the management of several other types of cancer. Since sex hormones are actively employed in stimulation and the control of proliferation and function of certain tissues, including the mammary and prostate glands, cancer arising from other tissues may be inhibited or stimulated by appropriate changes in hormonal balance. Cancer of breast and of prostate can be effectively treated with sex hormone therapy or ablation of appropriate endocrine organs.

 

    The mechanism of action of steroid hormones have been partially clarified. Most steroid sensitive cancers express specific cell surface receptors

 

    Estrogen sensitive breast cancers, prednisone sensitive lymphomas express receptors for estrogen and corticosteroids. It is now possible to assay tumor specimens for steroid receptors content and to identify which individual patients are likely to benefit from hormonal therapy. High dose of estrogen is useful therapeutically in metastatic breast cancer,but is replaced by anti-estrogen therapy.

Estrogen and androgen inhibitors-tamoxifen (antiestrogen)

 

• Biologic response modifiers

 

    The interferons are a family of proteins produced by nucleated cells and by recombinant DNA technology.

    The mechanism of IFN α's anti tumor action are complex. IFN increases the activity of cytotoxic cells within the immune system,but direct antiproliferative effects also play a role. IFN prolong the cell cycle which result in cytostasis,an increase in cell size and apoptosis. They can inhibit new blood vessel formation in tumor and can increase expression of antigen on tumor cell surface making the cancerous cell more easily recognized by thew cell of immune system. They can also inhibit or block certain oncogenes that can direct an unregulated cell growth that is characteristic of cancerous cells.

 

    Interleukin-2(IL-2)is a lymphokine produced recombinanatly that has diverse immunologic effects.IL-2 promote B and T cell proliferation and differentiation and initiate a cytokine cascade with multiple interacting immunologic effects. Anti tumor effects depends on proliferation of a variety of cytotoxic cells that can recognize and destroy tumor cells without damaging normal cells. Some of these cytotoxic cells are natural killer (NK)cells,lymphokine-activated killer(LAT)cells,tumor infiltrating lymphocytes(TIL).

 

• Monoclonal antibodies

 

    The monoclonal antibodies have become important biologic response modifiers used in treatment of cancer. There are currently four agents approved for use as anti cancer agents within US – trastuzumab,rituximab,gemtuzumab and alemtuzumab. These agents consist of specific immunoglobulin sequences that are known to recognize a specific antigen or protein on the surface of cells. There are several mechanisms by which monoclonal antibodies may induce death of cancer cells. Direct mechanism include induction of apoptosis,blockage of a growth factor receptor,or induction anti idiotype antibodies. Important indirect mechanism include antibody dependant cellular toxicity (ADCC)and compliment mediated cellular toxicity.

 

• Heavy metal compounds

 

Cisplatin : it is a platinum complex with broad spectrum of anti tumor activity and remarkable in cancer treatment.

 

    Cisplatin's cytotoxicity depends on platinum binding to DNA and formation of intrastranded cross links or adducts between neighbouring guanines. These intra strand links cause a major bending of DNA. They may cause cellular damage by distorting normal DNA conformation and preventing bases that are normally paired from lining up with each other. Inter strand cross links also occur.

 

    Cisplatin is a highly toxic antineoplastic agent with potential for serious nephrotoxicity and anaemia.

 

    Carboplatin is a structural analogue of cisplatin. It shares same mechanism of action of cisplatin.

 

• Topoisomerase – targetting drugs

    Etoposide and teniposide: etoposide and teniposide are semisynthetic podophyllotoxin derivatives.

 

    DNA topoisomerase enzyme relieve torsional strain during DNA unwinding and by producing strand breaks. They cleave DNA strand , producing a gap through which DNA strand can pass , then they reseal the strand break. Topoisomerase 1 form single stranded breake and topoisomerase2 form double stranded break. Etoposide and teniposide , both form complex with topoisomerase2 and DNA that inhibit strand resealing.

 

    Irinotecan and topotecan poison the action of topoisomerase 1 enzyme.

 

 

INDOLE 3 CARBINOL

 

Alternative name: Indol-3-methanol, 3-indolmethanol

MV= 147,17; SMP= 96-99^oC

 

 

 

Figure 6

 

Description:

    Indole-3-carbinol or I3C is a breakdown product of the glucosinolate glucobrassicin, also known as indole-3-glucosinolate. Glucosinolates are beta-thioglucoside N-hydroxysulfates, which are primarily found in cruciferous vegetables (cabbage, broccoli sprouts, brussels sprouts, cauliflower, bok choy and kale).

    Indole-3-carbinol may have cancer chemopreventive activity. Glucosinolates themselves have minimal anticancer activity. Indole-3-carbinol is produced from indole-3-glucosinolate via the action of the enzyme myrosinase (thioglucoside glucohydrolase), an enzyme which is present in cruciferous vegetables and activated upon maceration of the vegetables.

    The possible anticancer activity of substances such as I3C was recognized by the Roman statesman, Cato the Elder (234-149 BC), who in his treatise on medicine wrote: "If a cancerous ulcer appears upon the breasts, apply a crushed cabbage leaf and it will make it well." Crushing a cabbage leaf would convert indole-3-glucosinolate to I3C, among other reactions.

What is it?

    Indole-3-carbinol is one of the major anticancer substances found in cruciferous (cabbage family) vegetables. It is a member of the class of sulfur-containing chemicals called glucosinolates.¹ It is formed from parent compounds whenever cruciferous vegetables are crushed or cooked.^2
3

    Indole-3-carbinol and other glucosinolates (e.g., other indoles and isothiocyanates such as sulforaphane) are antioxidants and potent stimulators of natural detoxifying enzymes in the body.^4
5 Indole-3-carbinol and other glucosinolates are believed to be responsible for the lowered risk of cancer in humans that is associated with the consumption of broccoli and other cruciferous vegetables like cauliflower, cabbage, and kale.^{6
7
8
9
10
11
12}

    Feeding indole-3-carbinol or broccoli extracts rich in indole-3-carbinol has dramatically reduced the frequency, size, and number of tumors in laboratory rats exposed to a carcinogen. It appears to be especially protective against breast^13
14
15
16 and cervical^17
18 cancers because of a number of actions, including an ability to increase the breakdown of estrogen. However, while most animal studies report protective effects, a few indicate that indole-3-carbinol may actually promote cancer formation in certain situations, depending upon the chemical initiator of cancer, method of exposure, and species of animal studied.^19
20

    Until there is further research and more human clinical data to determine if indole-3-carbinol actually inhibits rather than stimulates cancer formation, some researchers have recommended proceeding with caution when using isolated indole-3-carbinol as a dietary supplement.²¹ The areas where its use has currently been documented in humans are only preliminary, but the results are promising. Indole-3-carbinol reduced or halted the formation of precancerous lesions (papillomas) in 12 out of 18 people with recurrent respiratory tract papillomas.²² In addition, in a small double-blind trial, supplementation with 200 or 400 mg of indole-3-carbinol per day for 12 weeks reversed early-stage cervical cancer in 8 of 17 women.²³ Preliminary studies have also shown indole-3-carbinol has significantly increased the conversion of estrogen from cancer-producing forms to nontoxic breakdown products.^24
25

Where is it found?

    Indole-3-carbinol is found in highest concentrations in broccoli, but is also found in other cruciferous vegetables, such as cauliflower, cabbage, and kale.

Who is likely to be deficient?

    As indole-3-carbinol is not an essential nutrient, no deficiency state exists.

Actions and Pharmacology

Actions

    Indole-3-carbinol may modulate estrogen metabolism. It may also have anticarcinogenic, antioxidant and anti-atherogenic activities.

Mechanism of Action

    The estrogen metabolites 16 alpha-hydroxyestrone and 4-hydroxyestrone have been demonstrated to be carcinogens and are thought to be responsible for the possible carcinogenic effects of estrogen. On the other hand, the estrogen metabolite 2-hydroxyestrone has been found to be protective against several types of cancer, including breast cancer. Indole-3-carbinol has been shown to increase the ratio of 2-hydroxyestrone to 16 alpha-hydroxyestrone and also to inhibit the 4-hydroxylation of estradiol. Indole-3-carbinol increases 2-hydroxylation of estrogens via induction of cytochrome P4501A1 (CYP1A1). Indole-3-carbinol is converted by stomach acid to diindolymethane (DIM) and indole carbazole (ICZ). DIM and ICZ have similar activities regarding estrogen metabolism.

    Regarding its possible anticarcinogenic effects, indole-3-carbinol has been shown to modulate the activities of both Phase I enzymes, such as cytochrome P4501A1, -1A2, -2B1, -2B2, -3A1 and -3A2, and Phase II enzymes, such as glutathione S-transferase (GST), quinone reductase and uridine glucuronide transferase. Indole-3-carbinol modulates the metabolism of carcinogens, such as benzo(a)pyrene, aflatoxin B₁ and 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK). Indole-3-carbinol has also been shown to upregulate apoptosis in some cancer cell lines.

    As mentioned above, indole-3-carbinol induces the synthesis of 2-hydroxyestrone. 2-hydroxyestrone has been found to inhibit the oxidation of low-density lipoprotein. This indicates that indole-3-carbinol has indirect antioxidant activity. 2-hydroxyestrone also appears to inhibit smooth muscle proliferation. Inhibition of smooth muscle proliferation and inhibition of the oxidation of LDL could account for the possible anti-atherogenic activity of indole-3-carbinol.

    A number of mechanisms exist (that are not mutually exclusive)
whereby I3C (or DIM) can diminish the effects of estrogen on
tumor growth. First, I3C and DIM induce enzymes such as CYP1A1,
which converts estrone to 2-hydroxyestrone and ultimately
results in metabolites that are antiproliferative and proapoptotic. Alternative metabolism (16-hydroxylation) of estradiol
results in compounds that increase proliferation and anchorage
independent growth. Second, in the case of genes driven
by the estrogen receptor (ER)-, I3C acts as a negative regulator. The tumor suppressor breast cancer 1 (BRCA-1), whose
expression is upregulated by I3C/DIM, also inhibits the
expression of genes driven by ER-. Moreover, I3C and BRCA-1
work together to abrogate ER-–driven expression.
Using subtractive hybridization, Chen et al. determined
that expression of a battery of genes driven by estrogen was
abrogated by DIM. Speculation is that I3C/DIM and estradiol
modulate the ER and the aryl hydrocarbon receptor. Thus,
estrogen could modulate the activity of I3C/DIM as well. Finally,
in the absence of estrogen, I3C and DIM induce many genes that
have the potential to induce growth arrest and apoptosis and
therefore might counteract the effects of estradiol.

 

Biological Activities

Effects on Biotransformation Enzymes Involved in Carcinogen Metabolism

    Biotransformation enzymes play major roles in the metabolism and elimination of many biologically active compounds, including steroid hormones, carcinogens toxins and drugs. In general, phase I biotransformation enzymes, including the cytochrome P450 (CYP) family, catalyze reactions that increase the reactivity of hydrophobic (fat-soluble) compounds, preparing them for reactions catalyzed by phase II biotransformation enzymes. Reactions catalyzed by phase II enzymes generally increase water-solubility and promote the elimination of these compounds .

    Acid-condensation products of I3C, particularly DIM and indole[3,2-b]carbazole (ICZ), can bind to a protein in the cytoplasm of cells called the aryl hydrocarbon receptor (AhR) . Binding allows the AhR to enter the nucleus where it forms a complex with the Ahr nuclear translocator (Arnt) protein. This Ahr/Arnt complex binds to specific DNA sequences in genes known as xenobiotic response elements (XRE) and enhances their transcription. Genes for a number of CYP enzymes and several phase II enzymes are known to contain XREs. Thus, oral consumption of I3C results in the formation of acid condensation products that can increase the activity of certain phase I and phase II enzymes. Increasing the activity of biotransformation enzymes is generally considered a beneficial effect because the elimination of potential carcinogens or toxins is enhanced. However, there is a potential for adverse effects because some procarcinogens require biotransformation by phase I enzymes to become active carcinogens.

Alterations in Estrogen Activity and Metabolism

    Endogenous estrogens, including 17beta-estradiol, exert their estrogenic effects by binding to estrogen receptors (ERs). Within the nucleus, the estrogen-ER complex can bind to DNA sequences in genes known as estrogen response elements (EREs), recruit coactivator molecules and enhance the transcription of estrogen-responsive genes. Some ER-mediated effects, such as those that promote cellular proliferation in the breast and uterus, can increase the risk of developing estrogen-sensitive cancers.

Effects on Estrogen Receptor Activity

    When added to breast cancer cells in culture, I3C has been found to inhibit the transcription of estrogen-responsive genes stimulated by 17beta-estradiol. Acid condensation products of I3C that bind and activate AhR may also inhibit the transcription of estrogen-responsive genes by competing for coactivators or increasing ER degradation. In contrast, some studies in cell culture and animal models have found that acid-condensation products of I3C enhance the transcription of estrogen-responsive genes. Further research is needed to determine the nature of the stimulatory and inhibitory effects of I3C and its acid-condensation products on estrogen-responsive gene transcription under conditions that are relevant to human cancer risk.

Effects on Estrogen Metabolism

    The endogenous estrogen 17beta-estradiol can be irreversibly metabolized to 16alpha-hydroxyestrone (16OHE1) or 2-hydroxyestrone (2OHE1). In contrast to 2OHE1, 16OHE1 is highly estrogenic and has been found to stimulate the proliferation of several estrogen-sensitive cancer cell lines. It has been hypothesized that shifting the metabolism of 17beta-estradiol toward 2OHE1 and away from 16OHE1 could decrease the risk of estrogen sensitive cancers, such as breast cancer. In controlled clinical trials, oral supplementation with 300-400 mg/day of I3C has consistently increased urinary 2OHE1 levels or urinary 2OHE1:16OHE1 ratios in women. Supplementation with 108 mg/day of DIM also increased urinary 2OHE1 levels in postmenopausal women. However, the relationship between urinary 2OHE1:16OHE1 ratios and breast cancer risk is not clear. Although women with breast cancer had lower urinary ratios of 2OHE1:16OHE1 in several small case-control studies , larger case-control and prospective cohort studies have not found significant associations between urinary 2OHE1:16OHE1 ratios and breast cancer risk.

Induction of Cell Cycle Arrest

    Once a cell divides, it passes through a sequence of stages collectively known as the cell cycle before it divides again. Following DNA damage, the cell cycle can be transiently arrested at damage checkpoints which allow for DNA repair or activation of pathways leading to cell death (apoptosis) if the damage is irreparable. Defective cell cycle regulation may result in the propagation of mutations that contribute to the development of cancer. The addition of I3C to prostate and breast cancer cells in culture has been found to induce cell cycle arrest. However, the physiological relevance of these cell culture studies is unclear since little or no I3C is available to the tissue after oral administration.

Induction of Apoptosis

    Unlike normal cells, cancerous cells lose their ability to respond to death signals by undergoing apoptosis. I3C and DIM have been found to induce apoptosis when added to cultured prostate, breast and cervical cancer cells.

Inhibition of Tumor Invasion and Angiogenesis

    Limited evidence in cell culture experiments suggests that I3C and DIM can inhibit the invasion of normal tissue by cancer cells and inhibit the development of new blood vessels (angiogenesis) required by tumors to fuel their rapid growth.

Disease Prevention

Cancer

Epidemiological Studies

    Epidemiological studies provide some support for the hypothesis that higher intakes of cruciferous vegetables are associated with lower risk for some types of cancer. However, cruciferous vegetables are relatively good sources of other phytonutrients that may have protective effects against cancer, including vitamin C, folate, selenium, carotenoids and fiber. Moreover, cruciferous vegetables provide a variety of glucosinolates that may be hydrolyzed to a variety of potentially protective isothiocyanates, in addition to indole-3-carbinol. Consequently, evidence for an inverse association between cruciferous vegetable intake and cancer risk provides relatively little information about the specific effects of indole-3-carbinol on cancer risk.

Animal Studies

    In most animal models, exposure to a chemical carcinogen is required to cause cancer. When administered before or at the same time as the carcinogen, oral I3C has been found to inhibit the development of cancer in a variety of animal models and tissues, including cancers of the mammary gland (breast), stomach, colon, lung and liver. However, a number of studies have found that I3C actually promoted or enhanced the development of cancer when administered chronically after the carcinogen (post initiation). The cancer promoting effects of I3C were first reported in a trout model of liver cancer. However, I3C has also been found to promote cancer of the liver, thyroid, colon and uterus in rats. Although the long-term effects of I3C supplementation on cancer risk in humans are not known, the contradictory results of animal studies have led several experts to caution against the widespread use of I3C and DIM supplements in humans until their potential risks and benefits are better understood.

Disease Treatment

Diseases Related to Human Papilloma Virus Infection

Cervical Intraepithelial Neoplasia

    Infection with certain strains of human papilloma virus (HPV) is an important risk factor for cervical cancer. Transgenic mice that express cancer-promoting HPV genes develop cervical cancer with chronic 17beta-estradiol administration. In this model, feeding I3C markedly reduced the number of mice that developed cervical cancer. A small placebo-controlled trial in women examined the effect of oral I3C supplementation on the progression of precancerous cervical lesions classified as cervical intraepithelial neoplasia (CIN) 2 or CIN 3. After 12 weeks, four out of the eight women who took 200 mg/day had complete regression of CIN and four out of the nine who took 400 mg/day had complete regression, while none of the ten who took a placebo had complete regression. Although these preliminary results are encouraging, larger controlled clinical trials are needed to determine the efficacy of I3C supplementation for preventing the progression of precancerous lesions of the cervix.

Recurrent Respiratory Papillomatosis

    Recurrent respiratory papillomatosis (RRP) is a rare disease of children and adults, characterized by generally benign growths (papillomas) in the respiratory tract caused by HPV infection. These papillomas occur most commonly on or around the vocal cords in the larynx (voice box), but they may also affect the trachea, bronchi and lungs. The most common treatment for RRP is surgical removal of the papillomas. Since papillomas often recur, adjunct treatments may be used to help prevent or reduce recurrences. In immune-compromised mice transplanted with HPV-infected laryngeal tissue, only 25% of the mice fed I3C developed laryngeal papillomas, compared to 100% of the control mice. In a small observational study of RRP patients, increased ratios of urinary 2OHE1:16OHE1 ratios resulting from increased cruciferous vegetable consumption were associated with less severe RRP. Most recently, an uncontrolled pilot study examined the effect of daily I3C supplementation (400 mg for adults and 10 mg/kg daily for children) on papilloma recurrence in RRP patients. Over a five-year follow-up period, 11 of the original 49 patients experienced no recurrence, 10 experienced a reduction in the rate of recurrence, 12 experienced no improvement, and 12 were lost to follow-up. Although the low toxicity of I3C makes it an attractive adjunct therapy for RRP, controlled clinical trials are needed to determine whether I3C is effective in preventing or reducing the recurrence of respiratory papillomas.

 

 

Systemic Lupus Erythematosus

    Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by chronic inflammation that may result in damage to the joints, skin, kidneys, heart, lungs, blood vessels or brain. Estrogen is thought to play a role in the pathology of SLE because the disorder is much more common in women than men, and its onset is most common during the reproductive years when endogenous estrogen levels are highest. The potential for I3C supplementation to shift endogenous estrogen metabolism toward the less estrogenic metabolite 2OHE1 and away from the highly estrogenic metabolite 16OHE1 led to interest in its use in SLE (25). In an animal model of SLE, I3C feeding decreased the severity of renal (kidney) disease and prolonged survival. A small uncontrolled trial of I3C supplementation (375 mg/day) in female SLE patients found that I3C supplementation increased urinary 2OHE1:16OHE1 ratios, but found no significant change in SLE symptoms after 3 months. Controlled clinical trials are needed to determine whether 13C supplementation will have beneficial effects in SLE patients.

Pharmacokinetics

    There is much unknown about the pharmacokinetics of indole-3-carbinol in humans. It is converted to DIM and ICZ by stomach acid, and DIM and ICZ are absorbed from the gastrointestinal tract. The extent of absorption of I3C, DIM and ICZ, as well as their distribution, metabolism and excretion, are currently being studied.

Metabolism and Bioavailability

    A number of commonly consumed cruciferous vegetables, including broccoli, Brussels sprouts and cabbage, are good sources of glucobrassicin, the glucosinolate precursor of I3C. Myrosinase, an enzyme that catalyzes the hydrolysis of glucosinolates, is physically separated from glucosinolates in intact plant cells (3). When plant cells are damaged, as when cruciferous vegetables are chopped or chewed, the interaction of myrosinase and glucobrassicin results in the formation of I3C. In the acidic environment of the stomach, I3C molecules can combine with each other to form a complex mixture of biologically active compounds, known collectively as acid condensation products. Although numerous acid condensation products of I3C have been identified, some of the most prominent include the dimer 3,3'-diindolylmethane (DIM) and a cyclic trimer (CT). The biological activities of individual acid condensation products differ from those of I3C and are responsible for the biological effects attributed to I3C. When plant myrosinase is inactivated (e.g., by boiling), glucosinolate hydrolysis still occurs to a lesser degree, due to the myrosinase activity of human intestinal bacteria . Thus, when cruciferous vegetables are cooked in a manner that inactivates myrosinase, glucobrassicin hydrolysis by intestinal bacteria still results in some I3C formation. However, acid condensation products would be less likely to form in the more alkaline environment of the intestine.

Safety

Adverse effects

    Slight increase in serum concentration of a liver enzyme (alanine aminotransferase; ALT) were observed in two women who took unspecified doses of 13 C supplements for four weeks. One person reported a skin rash while taking 375mg/kg of 13C. High doses of 13C were associated with symptoms of disequilibrium and tremor, which resolved when the dose decreased. The effects of 13C or DIM supplementation on cancer risk in humans are not known.

Pregnancy and lactation

The safety of 13C or DIM supplements during pregnancy or lactation has not been established.

Drug interaction

    No drug interaction in humans have been reported.

    Antacids, H2 blocker , proton pump inhibitors: The conversion of 13C to DIM or ICZrequire stomach acid. It is unclear if indole 3 carbinol itself would have all the possible activities mentioned above if it were not converted to DIM or ICZ.

    Tamoxiphen : indole 3 carbinol may be synergestic with tamoxiphen in protecting against breast cancer.

Contraindications

    Indole-3-carbinol is contraindicated in those hypersensitive to this substance or to any component of an indole-3-carbinol-containing product.

Precautions

    Pregnant women and nursing mothers should avoid indole-3-carbinol supplements pending long-term safety studies. Those with cancer should confer with their physician before deciding to use indole-3-carbinol.

Dosage and Administration

    Indole-3-carbinol is available as a stand-alone supplement and in combination products. Dosage ranges from 200 mg to 800 mg daily.

    Indole-3-carbinol, as well as diindolylmethane, are available in combination formulas used by some body builders.

Clinical Trials

Indole-3-Carbinol in Preventing Cancer in Healthy Participants

This study is currently recruiting patients

 
Purpose

    RATIONALE: Chemoprevention is the use of certain drugs to keep cancer from forming, growing, or coming back. The use of indole-3-carbinol may prevent cancer.

    PURPOSE: This randomized phase I trial is studying the side effects and best dose of indole-3-carbinol and to see how well it works compared to placebo in preventing cancer in healthy participants.

Condition	Intervention	Phase
unspecified adult solid tumor, protocol specific	Drug: indole-3-carbinol  Procedure: biologically based therapies  Procedure: cancer prevention intervention  Procedure: chemoprevention of cancer  Procedure: complementary and alternative therapy  Procedure: dietary intervention  Procedure: nutritional supplementation	Phase I

 

Study Type: Interventiona

Study Design: Prevention

Official Title: Phase I Randomized Chemoprevention Study of Indole-3-Carbinol in Healthy Participants

Further Study Details: 

Objectives

Primary

• Determine the maximum tolerated dose of indole-3-carbinol in healthy participants.
• Determine the safety and tolerability of this drug in these participants.
• Determine the pharmacokinetics of this drug in these participants.
• Secondary
• Determine the effects of this drug on selected markers of sexual function in these participants.
• Determine the effects of this drug on markers of susceptibility to cancer in these participants.

Outline

This is a randomized, double-blind, placebo-controlled, dose-escalation study. Participants at each dose level are randomized to 1 of 2 treatment arms.

• Arm I: Participants receive a single dose of oral indole-3-carbinol on day 1.
• Arm II: Participants receive a single dose of oral placebo on day 1. Cohorts of 3 participants receive escalating doses of indole-3-carbinol until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 1 of 3 participants experiences dose-limiting toxicity. An additional cohort of 3 participants is treated at the MTD.

Participants are followed on days 2, 3, and 6.

PROJECTED ACCRUAL: A total of 24 participants (18 in arm I and 6 in arm II) will be accrued for this study.

Eligibility

Ages Eligible for Study:  18 Years   - 70 Years,  Genders Eligible for Study:  Both

Accepts Healthy Volunteers

Criteria

Disease characteristics

• Healthy participants
• Non-smoker
• No drug abuse, as determined by urine cotinine and baseline drug screen

Patient characteristics

Age

• 18 to 70

Performance status

• Not specified

Life expectancy

• At least 12 months

Hematopoietic

• Absolute granulocyte count > 1,500/mm^3
• Hemoglobin > 10 g/dL

 

Hepatic

• Bilirubin < 1.8 mg/dL
• AST and ALT < 110 U/L
• Alkaline phosphatase < 300 U/L

Renal

• Creatinine < 2.0 mg/dL
• Albumin > 3.0 g/dL

Pulmonary

• No asthma

Other

• Not pregnant or nursing
• Negative pregnancy test
• Weight within 20% of ideal body weight by the Metropolitan Life table
• No serious drug allergies
• No arthritis
• No acute, unstable, chronic, or recurring medical condition
• No strict vegetarians
• No diabetes
• No evidence of an active malignancy
• No other serious intolerance or allergies
• Mild seasonal allergies allowed
• No other serious acute or chronic illness
• None of the following chronic conditions:
• Headaches
• Dysphoria
• Fatigue
• Dizziness
• Blurred vision
• Insomnia
• Rhinorrhea
• Nausea
• Vomiting
• Abdominal pain
• Diarrhea
• Constipation
• Premenstrual syndrome
• Cessation of menses within the past 10 days (menstruating women only)

Prior concurrent therapy

Biologic therapy

• Not specified

Chemotherapy

• No prior chemotherapy

Endocrine therapy

• Concurrent oral contraceptives allowed

Radiotherapy

• Not specified

Surgery

• Not specified

 

Other

• More than 21 days since prior medications, herbal products, dietary supplements, or high-dose vitamins
• More than 3 months since prior investigational drugs
• At least 14 days since prior and no concurrent ingestion of cruciferous vegetables, including any of the following:
• Broccoli
• Cabbage, including coleslaw
• Cauliflower
• Bok-choy
• Brussels sprouts
• Collards
• Kale
• Kohlrabi
• Mustard greens
• Rutabaga
• Turnip
• Watercress
• At least 7 days since prior and no concurrent alcohol consumption
• At least 48 hours since prior ingestion of grapefruit-containing foods and beverages
• No concurrent chronic drug therapy
• No other concurrent supplements, including dietary supplements, vitamins, herbal products, or over-the-counter medications

Indole-3-carbinol and tamoxifen cooperate to arrest the cell cycle of MCF-7 human breast cancer cells

    The current options for treating breast cancer are limited to excision surgery, general chemotherapy, radiation therapy, and, in a minority of breast cancers that rely on estrogen for their growth, antiestrogen therapy. The naturally occurring chemical indole-3- carbinol (I3C), found in vegetables of the Brassica genus, is a promising anticancer agent that we have shown previously to induce a G1 cell cycle arrest of human breast cancer cell lines, independent of estrogen receptor signaling. Combinations of I3C and the antiestrogen tamoxifen cooperate to inhibit the growth of the estrogen-dependent human MCF-7 breast cancer cell line more effectively than either agent alone. This more stringent growth arrest was demonstrated by a decrease in adherent and anchorage- independent growth, reduced DNA synthesis, and a shift into the G1 phase of the cell cycle. A combination of I3C and tamoxifen also caused a more pronounced decrease in cyclin-dependent kinase (CDK) 2- specific enzymatic activity than either compound alone but had no effect on CDK2 protein expression. Importantly, treatment with I3C and tamoxifen ablated expression of the phosphorylated retinoblastoma protein (Rb), an endogenous substrate for the G1 CDKs, whereas either agent alone only partially inhibited endogenous Rb phosphorylation. Several lines of evidence suggest that I3C works through a mechanism distinct from tamoxifen. I3C failed to compete with estrogen for estrogen receptor binding, and it specifically down-regulated the expression of CDK6. These results demonstrate that I3C and tamoxifen work through different signal transduction pathways to suppress the growth of human breast cancer cells and may, therefore, represent a potential combinatorial therapy for estrogen-responsive breast cancer.

Inhibitory effects of Indole-3-carbinol on invasion and migration in human breast cancer cells

    Indole-3-carbinol (I3C) is a promising phytochemical agent in chemoprevention of breast cancer. Our present study is the first description of I3C that significantly inhibits the cell adhesion, spreading and invasion associated with an up-regulation of PTEN (a tumor suppressor gene) and E-cadherin (a regulator of cell-cell adhesion) expression in T47-D human breast cancer cells. Therefore, I3C exhibits anti-cancer activities by suppressing breast tumor cell growth and metastatic spread. Metastatic breast cancer is a devastating problem, clinical application of I3C as a potent chemopreventive agent may be helpful in limiting breast cancer invasion and metastasis.

 

Indole 3 carbinol is a negative regulator of Estrogen

Abstract

    Studies increasingly indicate that dietary indole-3-carbinol
(I3C) prevents the development of estrogen-enhanced cancers
including breast, endometrial and cervical cancers. Epidemiological,
laboratory, animal and translational studies support the efficacy
of I3C. Whereas estrogen increases the growth and survival of
tumors, I3C causes growth arrest and increased apoptosis and
ameliorates the effects of estrogen. Our long-range goal is
to best use I3C together with other nutrients to achieve maximum
benefits for cancer prevention. This study examines the possibility
that induction of growth arrest in response to DNA damage (GADD)
in genes by diindolylmethane (DIM), which is the acid-catalyzed
condensation product of I3C, promotes metabolically stressed
cancer cells to undergo apoptosis. We evaluated whether genistein,
which is the major isoflavonoid in soy, would alter the ability
of I3C/DIM to cause apoptosis and decrease expression driven
by the estrogen receptor (ER)-. Expression of GADD was evaluated
by real-time reverse transcription–polymerase chain reaction.
Proliferation and apoptosis were measured by a mitochondrial
function assay and by fluorescence-activated cell sorting analysis.
The luciferase reporter assay was used to specifically evaluate
expression driven by ER-. The estrogen-sensitive MCF-7 breast
cancer cell line was used for these studies. We show a synergistic
effect of I3C and genistein for induction of GADD expression,
thus increasing apoptosis, and for decrease of expression driven
by ER-. Because of the synergistic effect of I3C and genistein,
the potential exists for prophylactic or therapeutic efficacy
of lower concentrations of each phytochemical when used in combination.

Results

    It was hypothesized that certain genes may be instrumental in determining
how I3C/DIM ameliorates estrogen induction of tumor growth and
eventually causes growth arrest and apoptosis of these cells
(Fig. 1). We considered the involvement of GADD because of
our recent information that their expression is robustly upregulated
by DIM. GADD are a group of proteins (GADD-153, GADD-45,
-ß and - and GADD-34) that induce growth arrest and
apoptosis by different pathways. Moreover, BRCA-1, which is
induced by I3C/DIM, not only induces expression to GADD-45
but also inhibits estrogen signaling that is dependent on ER-. Finally, as shown below, genistein also can induce expression
of GADD and can affect ER signaling.

 

FIGURE 1  Model for a subset of genes induced by indole-3-carbinol/diindolylmethane (I3C/DIM) that may counteract estrogen-enhanced tumors.

 

 

 

 

 

 

DIM and genistein synergistically induce GADD

 

    Genistein, an isoflavonoid from soy that is considered to be
an anticancer phytochemical, inhibits glucose-regulated
protein. This activity would counteract the protective
response to ER stress, and raises the possibility that genistein
could be an adjunct to I3C/DIM by modulation of the endoplasmic
reticulum stress response in the direction of increased growth
arrest and apoptosis. We first asked how genistein might affect
the expression of GADD. We evaluated effects of DIM and genistein
separately and together on the expression of GADD and used real-time
RT-PCR to measure the response in estrogen-sensitive MCF-7 cells.
As shown in Figure 2A, a short-time (6-h) treatment with either
DIM (100 or 50 µmol/L) or genistein (5 or 25 µmol/L)
increases expression of GADD-34. Very little increase is detected
using 25 µmol DIM/L. However the combination of 5 µmol
genistein/L and 25 µmol DIM/L results in a synergistic
increase in the expression of this GADD. Results also are shown
for GADD-153 ( Fig. 2B) and GADD-45 ( Fig. 2C). Similar results
occur with the other isoforms of GADD-45 and are virtually identical
in C33A cells (unpublished data).

 

FIGURE 2  DIM and genistein synergistically induce growth arrest in response to DNA damage (GADD). MCF-7 cells were treated with dimethyl sulfoxide (DMSO, a solvent control), genistein, DIM or both DIM and genistein for 16 h. The cDNA made from mRNA was used as a template to amplify GADD-34 (A), GADD-153 (B), GADD-45 (C) and ß-actin by real-time reverse transcription–polymerase chain reaction (RT-PCR) as described in Methods and Materials. Treatment of cells was DMSO (1), 100 µmol DIM/L (2), 50 µmol DIM/L (3), 25 µmol DIM/L (4), 25 µmol genistein/L (5), 5 µmol genistein/L (6) and the combination of 25 µmol DIM/L + 5 µmol genistein/L (7). The amount of estrogen in media (10% fetal calf serum) was 10-15 mol/L.

 

 

 

DIM and genistein synergistically increase apoptosis

    If DIM and genistein synergistically induce GADD, then growth
arrest and apoptosis should be a consequence of this induction.
We used two methods [a mitochondrial function assay and fluorescence-activated
cell sorting (FACS) analysis] to evaluate growth arrest and
apoptosis. In the mitochondrial function assay ( Fig. 3), DIM
and genistein work together to decrease cell viability. When
increasing concentrations of DIM are used together with 5 µmol
genistein/L (a concentration of genistein that enhances growth
in MCF-7 cells when used alone), increased killing of cells
occurs at concentrations of DIM as low as 20 µmol/L ( Fig.
3A) compared to the requirement for DIM concentrations to be
>50–60 µmol/L when cells are exposed to DIM alone.
DIM (50 µmol/L) counteracts the proliferative effect of
genistein, and genistein (used at increasing concentrations)
potentiates cell killing by DIM ( Fig. 3B). Using FACS analysis
( Fig. 4A), the profiles of subdiploid (putative apoptotic cells,
M1), G1 (M2), S (M3) and G2 (M4) are identical for cells treated
for 24 h with DMSO (solvent control), 25 µmol DIM/L or
5 µmol genistein/L. However, the fraction of putatively
apoptotic cells is dramatically increased when cells are treated
with the combination of both DIM and genistein ( Fig. 4, A and
B). Results with C33A cells (both assays) are identical to those
of MCF-7 cells.

 

FIGURE 3  DIM and genistein work together to decrease viability. MCF-7 cells were treated for 72 h with DMSO (solvent controls), or 5 µmol genistein/L and increasing amounts of DIM from 0 to 100 µmol/L (A) or 50 µmol DIM/L and increasing amounts of genistein from 0 to 50 µmol/L (B). A minimum of six replicate wells was employed per condition. Viability was determined by a mitochondrial function assay [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS)]. The amount of estrogen in media (10% fetal calf serum) was 10-15 mol/L.

 

 

FIGURE 4  DIM and genistein synergistically increase apoptotic cells. MCF-7 cells were treated with DMSO, 25 µmol DIM/L, 5 µmol genistein/L or 25 µmol DIM/L + 5 µmol genistein/L. Cells were treated for 48 h, stained with propidium iodide and sorted by fluorescence (abscissa). (top and middle panels) M1, subN2 cells; M2, G1; M3, S; M4, G2/M. (bottom panel) The gated percent values of M1 cells for the four conditions were 6.5, 4.8, 4.4 and 42.3%.

 

DIM and genistein synergistically decrease estrogen signaling driven by ER-

 

    Because genistein is a weak estrogen but able to compete
with estradiol for the ER, we wanted to know what the
effect of I3C and genistein together have on the expression
of genes driven by the ER- ( Fig. 5). Using MCF-7 cells treated
with I3C (50 µmol/L), genistein (25 µmol/L) or the
combination of I3C and genistein, we evaluated the amount of
luciferase that genes produce when driven by an estrogen-responsive
enhancer as described previously. I3C decreases estrogen-driven
luciferase activity. Treatment with genistein results in an
even greater decrease. Treatment with the two phytochemicals
reduces expression significantly more than would have been predicted
if the effect of the two phytochemicals were additive, which
indicates a clearly synergistic effect.

 

 

FIGURE 5  DIM and genistein synergistically inhibit estrogen signaling. MCF-7 monolayers were transfected with a plasmid that expresses estrogen receptor- and a plasmid for luciferase expression driven by the estrogen response element (ERE). The cells were then treated with ±1 µmol estradiol/L, ±25 µmol/L genistein and ±50 µmol I3C/L and were assayed for luciferase activity 24 h later as described in Methods and Materials. The final bar is not experimental data but the theoretical value if the effects of genistein and I3C had been additive.

 

Discussion

    We provide insight into additional mechanisms whereby I3C/DIM
can counteract the growth and survival of tumors in estrogen-sensitive
cells. We performed additional analysis that confirms that not
only does DIM induce GADD, but also that DIM and genistein synergistically
induce expression of GADD. Consistent with their effects on
the induction of GADD proteins, genistein and DIM work better
together than alone to increase apoptosis. Another way by which
I3C/DIM can lead to the growth arrest of estrogen-sensitive
cancer cells is by interfering with estrogen signaling. Here,
too, genistein and DIM are synergistic in inhibiting estrogen
signaling by ER-.

    Our discovery that DIM induces GADD and other proteins involved
in the endoplasmic reticulum stress response not only
supports the possibility that GADD contribute to the growth
arrest and apoptosis associated with I3C/DIM, but also may answer
(at least in part) why I3C/DIM seems to specifically target
tumor cells opposed to normal cells. The importance of the tumor
microenvironment in malignant progression has received much
less attention in the literature than the cellular events that
trigger oncogenesis. Tumor cells protect themselves from changes
in the microenvironment such as decreased availability of oxygen
and nutrients by engaging a biochemical pathway called the metabolic
stress response. In vivo cancer cells are likely to be chronically
stressed. The cellular response to hypoxia, hypoglycemia and
nutrient starvation includes the synthesis of protective proteins
and cell cycle arrest, which can lead to apoptosis or survival
and also can involve induction of genes that promote angiogenesis
and tissue remodeling. In other words, the fate of the stressed
cell is survival by adaptation to the stressful conditions or
elimination by programmed cell death. Obviously, the desired
outcome for cancer prevention is growth arrest and apoptosis.

    The fact that genistein works synergistically with I3C/DIM has
a number of implications. Importantly (at least for induction
of GADD, apopotosis and inhibition of estrogen-increased gene
expression), the concentrations of these phytochemicals used
in vitro to achieve these activities are more in line with concentrations
that people acquire from eating the relevant foods. Additionally,
people are exposed to combinations of foods and their bioactive
constituents. Although sorting out how diets ultimately may
affect a cell necessarily involves evaluating individual nutrients,
the study of interactions between nutrients (especially well-studied
nutrients) is the next step. Clearly, the Asian diet, which
is considered protective against breast and some other cancers,
must involve many bioactive compounds and their interactions.

Dose-ranging study of indole-3-carbinol for breast cancer prevention

    Sixty women at increased risk for breast cancer were enrolled in a placebo-controlled, double-blind dose-ranging chemoprevention study of indole-3-carbinol (I3C). Fifty-seven of these women with a mean age of 47 years (range 22-74) completed the study. Each woman took a placebo capsule or an I3C capsule daily for a total of 4 weeks; none of the women experienced any significant toxicity effects. The urinary estrogen metabolite ratio of 2-hydroxyestrone to 16 alpha- hydroxyestrone, as determined by an ELISA assay, served as the surrogate endpoint biomarker (SEB). Perturbation in the levels of SEB from baseline was comparable among women in the control (C) group and the 50, 100, and 200 mg low-dose (LD) group. Similarly, it was comparable among women in the 300 and 400 mg high-dose (HD) group. Regression analysis showed that peak relative change of SEB for women in the HD group was significantly greater than that for women in the C and LD groups by an amount that was inversely related to baseline ratio; the difference at the median baseline ratio was 0.48 with 95% confidence interval (0.30, 0.67). No other factors, such as age and menopausal status, were found to be significant in the regression analysis. The results in this study suggest that I3C at a minimum effective dose schedule of 300 mg per day is a promising chemopreventive agent for breast cancer prevention. A larger study to validate these results and to identify an optimal effective dose schedule of I3C for long-term breast cancer chemoprevention will be necessary.

 

Indole-3-carbinol (I3C) induced cell growth inhibition, G1 cell cycle arrest and apoptosis in prostate cancer cells

     Prostate cancer is one of the most common cancers in men and it is the second leading cause of cancer related death in men in the United States. Recent dietary and epidemiological studies have suggested the benefit of dietary intake of fruits and vegetables in lowering the incidence of prostate cancer. A diet rich in fruits and vegetables provides phytochemicals, particularly indole-3-carbinol (I3C), which may be responsible for the prevention of many types of cancer, including hormone-related cancers such as prostate. Studies to elucidate the role and the molecular mechanism(s) of action of I3C in prostate cancer, however, have not been conducted. In the current study, we investigated whether I3C had any effect against prostate cancer cells and, if so, attempts were made to identify the potential molecular mechanism(s) by which I3C elicits its biological effects on prostate cancer cells. Here we report for the first time that I3C inhibits the growth of PC-3 prostate cancer cells. Induction of G1 cell cycle arrest was also observed in PC-3 cells treated with I3C, which may be due to the observed effects of I3C in the up-regulation of p21(WAF1) and p27(Kip1) CDK inhibitors, followed by their association with cyclin D1 and E and down-regulation of CDK6 protein kinase levels and activity. The induction of p21(WAF1) appears to be transcriptionally upregulated and independent of the p53 responsive element. In addition, I3C inhibited the hyperpohosphorylation of the Retinoblastoma (Rb) protein in PC-3 cells. Induction of apoptosis was also observed in this cell line when treated with I3C, as measured by DNA laddering and poly (ADP-ribose) polymersae (PARP) cleavage. We also found an up-regulation of Bax, and down-regulation of Bcl-2 in I3C-treated cells. These effects may also be mediated by the down-regulation of NF-kappaB observed in I3C treated PC-3 cells. From these results, we conclude that I3C inhibits the growth of PC-3 prostate cancer cells by inducing G1 cell cycle arrest leading to apoptosis, and regulates the expression of apoptosis-related genes. These findings suggest that I3C may be an effective chemopreventive or therapeutic agent against prostate cancer.

 

Indole-3-Carbinol with Standardized Broccoli 200 mg/150 mg, 60 capsules

    Indole-3-carbinol is a plant compound from cruciferous vegetables, such as broccoli and cauliflower, that has shown impressive results in maintaining healthy cell growth.49-52* Broccoli contains several compounds that help maintain healthy DNA function.* The broad-spectrum benefits of cruciferous vegetables have now been combined into one capsule. The proprietary 3:1 blend of broccoli sprout concentrate provides sulforaphane for immediate absorption and glucosinolates, which must be broken down in the body to provide a broad spectrum of isothiocyanates.

    Unlike other products on the market that contain only the isothiocyanate sulforaphane, I3C with Standarized Broccoli contains standardized levels of glucosinolates. Glucosinolates are precursors or the "parent" compound that include a natural spectrum of isothiocyanates. Glucosinolates are sulfur-containing phytonutrients, which are part of the genus Brassicaceae. It has been estimated that there are over 120 different glucosinolates known to exist in nature. Epidemiological (population) studies have demonstrated that glucosinolates found in these vegetables have health benefits and show supporting effects in maintaining healthy cells in the stomach, lung, and colon.

 

 

 

Figure 7

 

 

Supplement Facts

Serving Size 1 capsule

Servings Per Container 60

Amount Per Serving

Indole-3-Carbinol

200 mg

Broccoli sprout concentrate (Brassica oleracea) [standardized for 0.3% sulforaphane (0.45 mg), 1% total glucosinolates (1.5 mg)]

150 mg

Other ingredients: rice flour, gelatin, magnesium stearate, titanium dioxide.

 

Dosage and Use

• One capsule per day for individuals weighing up to 179 pounds.
• Those weighing over 239 pounds, take two capsules per day.
• Indole-3-Carbinol with Standardized Broccoli also comes in a 300 mg dose for those weighing 180-239 pounds and only requires one capsule per day.
• This product can be taken with or without food.

 

Warning

 

• Keep out of reach of children
• Do not exceed recommended dose.
• Do not purchase if outer seal is broken or damaged.
• If you have a bad reaction to product discontinue use immediately
• When using nutritional supplements, please inform your physician if you are undergoing treatment for a medical condition or if you are pregnant or lactating.

 

 

CONCLUSION

 

Metastatic breast cancer is a devastating problem. Clinical application of indole 3 carbinol as a potent chemopreventive agent may be helpful in limiting breast cancer invasion and metastasis. Many evidences suggest that intake of cruciferous vegetables which are good source of indole 3 carbinol will help in lowering the risk of some types of cancers.

 

 

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       Cite this: C. Deepa Nair, Toji Tom, "Indole 3 carbinol, a novel approach to cancer

       treatment", B. Pharm Projects and Review Articles, Vol. 1, pp. 234-298, 2006. (http://farmacists.blogspot.in/)