3, 3'-Diindolylmethane enhances the effectiveness of herceptin against HER-2/neu-expressing breast cancer cells.

Herceptin failure is a major clinical problem in breast cancer. A subset of breast cancer patients with high HER-2/neu levels eventually experience metastatic disease progression when treated with Herceptin as a single agent. Mechanistic details of development of this aggressive disease are not clear. Therefore, there is a dire need to better understand the mechanisms by which drug resistance develops and to design new combined treatments that benefit patients with aggressive breast cancer and have minimal toxicity. We hypothesized that 3, 3'-diindolylmethane (DIM), a non-toxic agent can be combined with Herceptin to treat breast cancers with high levels of HER-2/neu. Here, we evaluated the effects of Herceptin alone and in combination with DIM on cell viability, apoptosis and clonogenic assays in SKBR3 (HER-2/neu-expressing) and MDA-MB-468 (HER-2/neu negative) breast cancer cells. We found that DIM could enhance the effectiveness of Herceptin by significantly reducing cell viability, which was associated with apoptosis-induction and significant inhibition of colony formation, compared with single agent treatment. These results were consistent with the down-regulation of Akt and NF-kB p65. Mechanistic investigations revealed a significant upregulation of miR-200 and reduction of FoxM1 expression in DIM and Herceptin-treated breast cancer cells. We, therefore, transfected cells with pre-miR-200 or silenced FoxM1 in these cells for understanding the molecular mechanism involved. These results provide experimental evidence, for the first time, that DIM plus Herceptin therapy could be translated to the clinic as a therapeutic modality to improve treatment outcome of patients with breast cancer, particularly for the patients whose tumors express high levels of HER-2/neu.

Genistein inhibits cell growth and induces apoptosis through up-regulation of miR-34a in pancreatic cancer cells.

Pancreatic cancer (PC) is the fourth most common cause of cancer-related deaths in the United States, suggesting that designing novel therapeutic strategy is required to improve the survival outcome of patients diagnosed with PC. Recently, microRNAs (miRNA) have been found to be involved in the regulation of multiple aspects of tumor development and progression including PC. In this study, we investigate whether miR-34a plays a critical role in the control of cell growth and apoptosis in PC cells. We found that Re-expression (forced expression) of miR-34a inhibits cell growth and induces apoptosis, with concomitant down-regulation of Notch-1 signaling pathway, one of the target of miR-34a. Moreover, treatment of PC cells with a natural compound genistein led to the up-regulation of miR-34a, resulting in the down-regulation of Notch-1, which was correlated with inhibition of cell growth, and induction of apoptosis. Our findings suggest that genistein could function as a non-toxic activator of a miRNA that can suppress the proliferation of PC cells.

The therapeutic value of natural agents to treat miRNA targeted breast cancer in African-American and Caucasian-American women.

Breast cancer is the most common cancer in women in the United States, with African-American (AA) women showing significantly higher rates than Caucasian-American (CA) women do. The reason for this racial disparity remains unknown, and factors that might be responsible for the differences in incidence and mortality have not been identified. One possible factor could be microRNAs (miRs), which are small noncoding regulatory RNAs involved intimately in cancer, and the expression of certain miRs may be decreased or increased in the breast tumors of AA and CA women. Therefore, modulation of miRs using natural agents could lead to the development of a novel therapeutic strategy to treat aggressive forms of breast cancer in women of different racial backgrounds. The function of natural agents in the regulation of miRs has not been investigated extensively. In this review, we will discuss the potential role of naturally occurring agents as potent antitumor agents thought to function by targeting miRs as contributing factors to the disparity in breast cancer between AA and CA women.

Novel targets for detection of cancer and their modulation by chemopreventive natural compounds.

Cancer affects the lives of millions of people. Several signaling pathways have been proposed as therapeutic targets for cancer therapy, and many more continue to be validated. With the identification and validation of therapeutic targets comes the question of designing novel strategies to effectively counter such targets. Natural compounds from dietary sources form the basis of many ancient medicinal systems. They are pleiotropic i.e. they act on multiple targets, and, therefore, are often the first agents to be tested against a novel therapeutic target. This review article summarizes the knowledge so far on some actively pursued targets - Notch, CXCR4, Wnt and sonic hedgehog (shh) pathways, the process of epithelial-mesenchymal transition (EMT) as well as molecular markers such as uPA-uPAR, survivin, FoxM1, and the microRNAs. We have performed an extensive survey of literature to list modulation of these targets by natural agents such as curcumin, indole-3-carbinol (I3C), 3,3'-diindolylmethane (DIM), resveratrol, epigallocatechin-3-gallate (EGCG), genistein etc. We believe that this review will stimulate further research for elucidating and appreciating the value of these wonderful gifts from nature.

3,3'-Diindolylmethane enhances taxotere-induced growth inhibition of breast cancer cells through downregulation of FoxM1.

Emerging evidence suggests that the transcription factor Forkhead Box M1 (FoxM1) is associated with aggressive human carcinomas, including breast cancer. Because elevated expression of FoxM1 has been observed in human breast cancers, FoxM1 has attracted much attention in recent years as a potential target for the prevention and/or therapeutic intervention in breast cancer. However, no information is currently available regarding how downregulation of FoxM1 could be achieved for breast cancer prevention and therapy. Here, we report for the first time that 3,3'-diindolylmethane (DIM), a nontoxic dietary chemopreventive agent could effectively downregulate FoxM1 in various breast cancer cell lines. Using gene transfection, real-time reverse transcription-PCR, Western blotting, invasion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, we found that DIM could enhance Taxotere-induced growth inhibition of breast cancer cells, and decreased invasive capacity of breast cancer cells was observed after either treatment alone or the combination. These effects were associated with downregulation of FoxM1. We also found that knock down of FoxM1 expression by small interfering RNA (siRNA) transfection increased DIM-induced cell growth inhibition, whereas over-expression of FoxM1 by cDNA transfection attenuated DIM-induced cell growth inhibition, suggesting the mechanistic role of FoxM1. Most importantly, the combination treatment significantly inhibited tumor growth in severe combined immunodeficiency (SCID) mice, and the results were correlated with the downregulation of FoxM1 in tumor remnants. We conclude that inactivation of FoxM1 and its target genes by DIM could enhance the therapeutic efficacy of Taxotere in breast cancer, which could be a useful strategy for the prevention and/or treatment of breast cancer.

Anticancer properties of indole compounds: mechanism of apoptosis induction and role in chemotherapy.

Indole compounds, obtained from cruciferous vegetables, have been investigated for their putative anti-cancer properties. Studies with indole-3-carbinol (I3C) and its dimeric product, 3, 3' diindolylmethane (DIM), have indicated efficacy of these compounds against a number of human cancers. Available as well as emerging data suggests that these compounds act on a number of cellular signaling pathways leading to their observed biological effects. Such pleiotropic effects of these compounds are also considered crucial for their chemosensitization activity wherein they help reduce the toxicity and resistance against conventional chemotherapeutic drugs. These observations have major clinical implications especially in chemotherapy. Through this review, we have attempted to update current understanding on the state of anti-cancer research involving indole compounds. We have also summarized the available literature on modulatory effects of indoles on molecular targets such as survivin, uPA/uPAR and signaling pathways such as the NF-kappaB pathway, which are important for the apoptosis-inducing and chemosensitizing properties of these compounds.

3,3'-Diindolylmethane enhances taxotere-induced apoptosis in hormone-refractory prostate cancer cells through survivin down-regulation.

Survivin, a member of inhibitor of apoptosis family, is associated with both prostate cancer progression and drug resistance. Therefore, we hypothesized that survivin may play a potentially important role in hormone-refractory prostate cancer (HRPC) and bone metastatic disease; thus, targeting of survivin signaling could enhance therapeutic efficacy in prostate cancer. 3,3'-Diindolylmethane (DIM) has been known to have cancer chemoprevention activity. However, no information is available regarding the down-regulation of survivin by DIM, which could result in the chemosensitization of HRPC cells to Taxotere-induced killing. We investigated the effect of DIM alone or in combination with Taxotere using LNCaP and C4-2B prostate cancer cells. We observed that DIM enhanced Taxotere-induced apoptotic death in both cell lines. These enhancing effects were related to a decrease in survivin expression as well as androgen receptor and nuclear factor-kappaB (NF-kappaB) DNA-binding activity. We also found that knockdown of survivin expression by small interfering RNA transfection increased DIM-induced cell growth inhibition and apoptosis, whereas overexpression of survivin by cDNA transfection abrogated DIM-induced cell growth inhibition and apoptosis in both prostate cancer cells. Importantly, luciferase assays showed a significant reduction of survivin-Luc and NF-kappaB-Luc activity in prostate cancer cells exposed to DIM and Taxotere. Furthermore, combination treatment significantly inhibited C4-2B bone tumor growth, and the results were correlated with the down-regulation of survivin. From these results, we conclude that inactivation of survivin by DIM enhanced the therapeutic efficacy of Taxotere in prostate cancer in general, which could be useful for the treatment of HRPC and metastatic prostate cancer.

Melatonin suppresses AOM/DSS-induced large bowel oncogenesis in rats.

The inhibitory effects of exogenous melatonin (MEL) on colon oncogenesis were investigated using an azoxymethane (AOM)/dextran sodium sulfate (DSS) rat model. Male F344 rats initiated with a single intraperitoneal injection of AOM (20mg/kg bw) were promoted by 1% (w/v) DSS in drinking water for 7 days. They were then given 0.4, 2 or 10ppm MEL in drinking water for 17 weeks. At week 20, the development of colonic adenocarcinoma was significantly inhibited by the administration with MEL dose-dependently. MEL exposure modulated the mitotic and apoptotic indices in the colonic adenocarcinomas that developed and lowered the immunohistochemical expression of nuclear factor kappa B, tumor necrosis factor alpha, interleukin-1beta and STAT3 in the epithelial malignancies. These results may indicate the beneficial effects of MEL on colitis-related colon carcinogenesis and a potential application for inhibiting colorectal cancer development in the inflamed colon.

Induction of growth arrest and apoptosis in human breast cancer cells by 3,3-diindolylmethane is associated with induction and nuclear localization of p27kip.

3,3'-Diindolylmethane (DIM) is a stable condensation product of indole-3-carbanol, a potential breast cancer chemoprevention agent. Human breast cancer cell lines were studied to better understand its mechanisms. In vitro experiments were done in MCF-7, T47D, BT-20 and BT-474 cells using MTT, ELISA, immunoblotting assays, reverse transcription-PCR, protein half-life, confocal microscopy, cell fractionation, and immunoprecipitation assays. We found that DIM inhibited the growth of all four breast cancer cell lines (IC(50)s, 25-56 micromol/L). Because BT-20 and BT-474 overexpressed Her-2 and activated Akt, and BT-20 lacks estrogen receptor, these were studied further. In both cell lines, DIM appeared to induce expression of p27(kip) protein before the loss of cell viability and apoptosis. In BT-20 cells, DIM also inhibited expression of activated Akt, but this appeared after p27(kip) induction. In both cell lines, DIM induced p27(kip) transcript expression within 6 h. DIM prolonged the p27(kip) protein half-life in BT-20 but not BT-474 cells. We also showed, for the first time, that DIM induced nuclear localization of p27(kip) in both cell lines. Moreover, in BT-20 cells, DIM induced a decrease in p27(kip) phosphorylation at Thr(187), and its association with the 14-3-3 protein, which helped to explain the protein half-life increase and nuclear localization, respectively. DIM modulates p27(kip) through transcription, prolongation of protein half-life, and nuclear localization. These effects appear to be independent of Her-2, Akt, or estrogen receptor status and should support further study for its chemoprevention potential in breast cancer.

Inactivation of NF-kappaB by 3,3'-diindolylmethane contributes to increased apoptosis induced by chemotherapeutic agent in breast cancer cells.

Constitutive activation of Akt or nuclear factor-kappaB (NF-kappaB) has been reported to play a role in de novo resistance of cancer cells to chemotherapeutic agents, which is a major cause of treatment failure in cancer chemotherapy. Previous studies have shown that 3,3'-diindolylmethane (DIM), a major in vivo acid-catalyzed condensation product of indole-3-carbinol, is a potent inducer of apoptosis, inhibitor of tumor angiogenesis, and inactivator of Akt/NF-kappaB signaling in breast cancer cells. However, little is known regarding the inactivation of Akt/NF-kappaB that leads to chemosensitization of breast cancer cells to chemotherapeutic agents, such as Taxotere. Therefore, we examined whether the inactivation Akt/NF-kappaB signaling caused by B-DIM could sensitize breast cancer cells to chemotherapeutic agents both in vitro and in vivo. MDA-MB-231 cells were simultaneously treated with 15 to 45 micromol/L B-DIM and 0.5 to 1.0 nmol/L Taxotere for 24 to 72 h. Cell growth inhibition assay, apoptosis assay, electrophoretic mobility shift assay, and Western blotting were done. The combination treatment of 30 micromol/L B-DIM with 1.0 nmol/L Taxotere elicited significantly greater inhibition of cell growth compared with either agent alone. The combination treatment induced greater apoptosis in MDA-MB-231 cells compared with single agents. Moreover, we found that NF-kappaB activity was significantly decreased in cells treated with B-DIM and Taxotere. We also have tested our hypothesis using transfection studies, followed by combination treatment with B-DIM/Taxotere, and found that combination treatment significantly inhibited cell growth and induced apoptosis in MDA-MB-231 breast cancer cells mediated by the inactivation of NF-kappaB, a specific target in vitro and in vivo. These results were also supported by animal experiments, which clearly showed that B-DIM sensitized the breast tumors to Taxotere, which resulted in greater antitumor activity mediated by the inhibition of Akt and NF-kappaB. Collectively, our results clearly suggest that inhibition of Akt/NF-kappaB signaling by B-DIM leads to chemosensitization of breast cancer cells to Taxotere, which may contribute to increased growth inhibition and apoptosis in breast cancer cells. The data obtained from our studies could be a novel breakthrough in cancer therapeutics by using nontoxic agents, such as B-DIM, in combination with other conventional therapeutic agents, such as Taxotere.

Therapeutic intervention of experimental breast cancer bone metastasis by indole-3-carbinol in SCID-human mouse model.

Several lines of experimental evidence have suggested that chemokine receptor CXCR4, a metastasis-promoting molecule, may play important roles in breast cancer bone metastasis. There is emerging evidence linking CXCR4 to matrix metalloproteinases (MMP) as well as their regulator nuclear factor-kappaB (NF-kappaB), a key transcription factor, which is known to activate metastasis-promoting molecules for many types of malignancies, including breast cancer. A recent study also showed that promoter region of CXCR4 has several NF-kappaB-binding sites, suggesting that there may be a cross-talk between CXCR4 and NF-kappaB. We have shown previously that indole-3-carbinol (I3C), a natural compound present in vegetables of the genus Brassica, can inhibit NF-kappaB in breast cancer cells. However, there are no reports in the literature showing any effect of I3C on CXCR4 expression in vitro and in vivo. We therefore examined whether I3C could inhibit bone metastasis of breast cancer by inhibiting CXCR4 and MMP-9 expression mediated via the inhibition of the NF-kappaB signaling pathway. Here, we have modified the severe combined immunodeficient (SCID)-human mouse model of experimental bone metastasis for use with the MDA-MB-231 breast cancer cell line. In this animal model, we found that I3C significantly inhibited MDA-MB-231 bone tumor growth, and our results were correlated with the down-regulation of NF-kappaB. Moreover, we found that I3C significantly inhibited the expression of multiple genes involved in the control of metastasis and invasion in vitro and in vivo, especially the expression of CXCR4 and MMP-9 along with pro-MMP-9, with concomitant decrease in Bcl-2 and increase in the proapoptotic protein Bax. From these results, we conclude that the CXCR4/NF-kappaB pathway is critical during I3C-induced inhibition of experimental breast cancer bone metastasis. These results also suggest that I3C could be a promising agent for the prevention and/or treatment of breast cancer bone metastasis in the future.

Epidermal growth factor receptor-related protein inhibits cell growth and invasion in pancreatic cancer.

The epidermal growth factor receptor (EGFR) signaling network plays critical roles in human cancers, including pancreatic cancer, suggesting that the discovery of specific agents targeting EGFR would be extremely valuable for pancreatic cancer therapy. EGFR-related protein (ERRP), a recently identified pan-erbB inhibitor, has been shown to inhibit growth and induce apoptosis of pancreatic cancer cells in vitro and tumor growth in a xenograft model. However, the precise molecular mechanism(s) by which ERRP exerts its antitumor activity remains unclear. The current investigation was undertaken to delineate the tumor growth inhibitory mechanism(s) of ERRP in pancreatic cancer cells. Using multiple molecular assays, such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, apoptosis, gene transfection, real-time reverse transcription-PCR, Western blotting, invasion, and electrophoretic mobility shift assay for measuring DNA-binding activity of nuclear factor-kappaB (NF-kappaB), we found that ERRP caused marked inhibition of pancreatic cancer cell growth. This was accompanied by increased apoptosis and concomitant attenuation of Notch-1 and NF-kappaB and down-regulation of NF-kappaB downstream genes, such as matrix metalloproteinase-9 and vascular endothelial growth factor, resulting in the inhibition of pancreatic cancer cell invasion through the Matrigel. We also found that down-regulation of Notch-1 by small interfering RNA before ERRP treatment resulted in enhanced cell growth inhibition and apoptosis. Our data suggest that the ERRP-mediated inactivation of EGFR, Notch-1, NF-kappaB, and its downstream target genes contributed to the inhibition of cell growth and invasion. We conclude that ERRP could be an effective agent for inhibiting tumor growth and invasion for the treatment of pancreatic cancer.

Down-regulation of notch-1 inhibits invasion by inactivation of nuclear factor-kappaB, vascular endothelial growth factor, and matrix metalloproteinase-9 in pancreatic cancer cells.

Notch signaling plays a critical role in the pathogenesis and progression of human malignancies but the precise role and mechanism of Notch-1 for tumor invasion remains unclear. In our earlier report, we showed that down-regulation of Notch-1 reduced nuclear factor-kappaB (NF-kappaB) DNA-binding activity and matrix metalloproteinase-9 (MMP-9) expression. Because NF-kappaB, VEGF, and MMPs are critically involved in the processes of tumor cell invasion and metastasis, we investigated the role and mechanism(s) by which Notch-1 down-regulation (using molecular approaches) may lead to the down-regulation of NF-kappaB, vascular endothelial growth factor (VEGF), and MMP-9, thereby inhibiting invasion of pancreatic cancer cells through Matrigel. We found that the down-regulation of Notch-1 by small interfering RNA decreased cell invasion, whereas Notch-1 overexpression by cDNA transfection led to increased tumor cell invasion. Consistent with these results, we found that the down-regulation of Notch-1 reduced NF-kappaB DNA-binding activity and VEGF expression. Down-regulation of Notch-1 also decreased not only MMP-9 mRNA and its protein expression but also inactivated the pro-MMP-9 protein to its active form. Taken together, we conclude that the down-regulation of Notch-1 could be an effective approach for the down-regulation and inactivation of NF-kappaB and its target genes, such as MMP-9 and VEGF expression, resulting in the inhibition of invasion and metastasis.

Suppressive effect of 1,4-phenylene diisothiocyanate on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced urinary bladder carcinogenesis in male ICR mice.

The modifying effects of dietary administration of 1,4-phenylene diisothiocyanate (DITC) on N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced urinary bladder carcinogenesis during the initiation and post-initiation phases were examined in male ICR mice. Five-week-old animals were divided into 5 groups. Groups 1-3 were given BBN (500 ppm) in drinking water for 6 weeks starting at age 6 week. Mice in Group 2 were given the diet containing 100 ppm DITC for 8 weeks during the initiation phase, starting 1 week before BBN exposure. Animals in Group 3 were fed the experimental diet for 24 weeks during the post-initiation phase starting 1 week after the cessation of BBN exposure. Mice in Group 4 were given only the diet containing the test compound, and those in Group 5 were given the basal diet alone throughout the experiment (32 weeks). The frequency of bladder lesions, neoplasms, dysplasia and hyperplasia, was analyzed histopathologically. The cell-proliferation activity estimated by the 5-bromodeoxyuridine labeling index (BrdU-LI), and cell cycle progression by counting cyclin D1-positive cell ratios were compared among the groups using immunohistochemistry. Administration of DITC in the initiation phase reduced significantly the incidence of urinary bladder carcinoma and dysplasia. The frequencies of any lesions of urinary bladder were not reduced by DITC in post-initiation phase. Dietary exposure of this agent in initiation phase reduced significantly both BrdU-LI and cyclin D1-positive cell ratios in any bladder lesions. Administration of DITC in post-initiation phase also significantly reduced BrdU-LI in bladder neoplasms and hyperplasia and cyclin D1-positive cell ratios in urinary bladder carcinoma as well as dysplasia. These results suggest that dietary DITC could be a preventive agent against BBN-induced bladder carcinogenesis in mice when fed during the initiation phase.

Inactivation of akt and NF-kappaB play important roles during indole-3-carbinol-induced apoptosis in breast cancer cells.

Despite significant advances in treatment, breast cancer is still the second leading cause of cancer-related deaths in women in the United States. Therefore, significant efforts are being given to develop novel strategies for the prevention of breast cancer in recent years. Our laboratory and others have been studying the effects of a potential chemopreventive agent, indole-3-carbinol (I3C), in breast cancer cells. We have previously shown that I3C induces apoptosis in breast cancer cells and found that the induction of apoptotic processes was partly mediated by dysregulation of anti- and pro-apoptotic molecules. However, the precise molecular mechanism(s) by which I3C induces apoptosis in breast cancer cells has not been fully elucidated. For the present study, we focused our investigation on important cell signaling molecules such as Akt and NF-kappaB during I3C-induced apoptosis in breast cancer cells. We found that I3C induces apoptotic processes in MCF10A-derived cell lines with premalignant (DCIS.com) and malignant (MCF10CA1a) phenotypes but not in nontumorigenic parental MCF10A cells. Immunoprecipitation, kinase assays, and Western blot analysis showed that I3C specifically inhibits Akt kinase activity and abrogates the EGF-induced activation of Akt in breast cancer cells. NF-kappaB DNA-binding analysis and transfection studies with Akt cDNA and NF-kappaB-Luc reporter constructs revealed that Akt gene transfection directly activates NF-kappaB, and this activation was completely abrogated by I3C treatment. In addition, I3C also abrogated the EGF-induced activation of NF-kappaB, which was mediated via the Akt signaling pathway. From these results, we conclude that there is a direct cross-talk between Akt and NF-kappaB pathways and that the inactivation of Akt and NF-kappaB activity plays important roles in mediating I3C-induced apoptosis in breast cancer cells. These results also suggest that I3C may be a potential chemopreventive agent by virtue of its selective apoptosis-inducing ability in premalignant and malignant breast epithelial cells.

Bax translocation to mitochondria is an important event in inducing apoptotic cell death by indole-3-carbinol (I3C) treatment of breast cancer cells.

Indole-3-carbinol (I3C), a natural component of Brassica vegetables, has been found to be a promising cancer preventive agent. However, the precise molecular mechanism(s) by which I3C exerts its inhibitory effects on cancer cells has not been fully elucidated. We investigated the molecular mechanism of action of I3C during apoptotic processes in breast epithelial cells. Nontumorigenic and tumorigenic breast epithelial cells were exposed to I3C, and growth inhibition, apoptosis and expression of genes involved in apoptotic processes were measured. Translocation of Bax to the mitochondria was accessed by confocal imaging. Mitochondrial potential and cytochrome c release also were measured. We found that I3C inhibited the growth of breast cancer cells and induced apoptosis in these cells, concomitant with upregulation of Bax, and downregulation of Bcl-2. I3C induced translocation of Bax to the mitochondria in both tumorigenic and nontumorigenic cells, but concomitant loss of mitochondrial potential, release of cytochrome c and induction of apoptosis were observed only in cancer cells. In conclusion, I3C exerts its effects by regulating cell cycle and by altering the expression of genes involved in apoptotic pathway. The translocation of Bax to the mitochondria alone is not sufficient during I3C-induced apoptosis. Translocation of Bax followed by mitochondrial depolarization and cytochrome c release is necessary, which may be responsible for selective induction of apoptosis in cancer cells, supporting the potential preventive and/or therapeutic benefit of I3C against cancers.

Indole-3-carbinol (I3C) induces apoptosis in tumorigenic but not in nontumorigenic breast epithelial cells.

Recent results from epidemiology, in vitro cell culture and in vivo (animal and human) studies have suggested the benefits of indole-3-carbinol (I3C) for the prevention of many types of cancer, including breast cancer. However, there are no reports, to the best of our knowledge, on the effect of I3C on isogenic nontumorigenic and tumorigenic breast epithelial cells, and there is a significant void in our understanding of the molecular mechanism(s) by which I3C induces apoptotic cell death in breast cancer cells. To fill this gap in our understanding, we conducted experiments to investigate the effects of I3C on an isogenic nontumorigenic (MCF10A) and tumorigenic (MCF10CA1a [CA1a]) breast epithelial cells. Here we show that CA1a cells are more sensitive to low concentration of I3C in terms of cell growth inhibition compared to MCF10A cells. We further report that I3C upregulates Bax/Bcl-2 ratio and downregulates Bcl-xL expression in CA1a cells but not in MCF10A cells. We also report, for the first time, that I3C induces Bax translocation to the mitochondria, causing mitochondrial depolarization, resulting in the loss of mitochondrial potential leading to the release of cytochrome c and subsequent cell death in CA1a cells but not in MCF10A cells. From these results, we conclude that I3C selectively induces apoptosis in breast cancer cells, but not in nontumorigenic breast epithelial cells, suggesting the potential therapeutic benefit of I3C against breast cancer.

Chemopreventive effects of melatonin on diethylnitrosamine and phenobarbital-induced hepatocarcinogenesis in male F344 rats.

The antitumor effects of melatonin on diethylnitrosamine (DEN)-initiated and/or phenobarbital (PB)-promoted hepatocarcinogenesis were investigated in male F344 rats. Five-week-old male F344 rats were divided into eight groups. Rats in groups 1-5 were given DEN (100 mg/kg body weight, i.p.) once a week for 3 wk, whereas those in groups 6-8 received vehicle treatment. Groups 1-3 and 7 were given 500 ppm PB in drinking water for 20 wk after DEN or vehicle treatment. Group 2 was given 400 ppm melatonin-containing diet during the initiation phase. Groups 3 and 5 were fed melatonin-containing diet for 20 wk, starting 1 wk after the last dosing of DEN. Group 6 was given melatonin-containing diet alone throughout the experiment (24 wk). Group 8 was treated with vehicle alone. Liver neoplasms were recognized only in DEN-treated groups. The incidences and multiplicities of hepatocellular adenoma and hepatocellular carcinoma (HCC) in group 3 were significantly smaller when compared with group 1 (P < 0.001 or P < 0.002). The average and unit areas of glutathione S-transferase placental form (GST-P)-positive foci of groups 2 and 3 were significantly smaller than those of group 1 (P < 0.001 or P < 0.01). The density and average area of these preneoplastic lesions of group 5 were also smaller than those of group 4 (P < 0.001 or P < 0.005). In addition, the ornithine decarboxylase activity in nonneoplastic liver tissue was reduced by melatonin treatment in both the initiation and postinitiation phases. These results suggest that melatonin has an antitumor-promoting ability in DEN-initiated and PB-promoted hepatocarcinogenesis in rats.

Steroid hormone mimics: molecular mechanisms of cell growth and apoptosis in normal and malignant mammary epithelial cells.

Anti-estrogen (anti-E2) therapy with E2 receptor antagonists has a significant benefit in women with breast cancer, but it may also increase the risk for developing hormone-independent breast cancer for which there is no therapy similar to that used in hormone-dependent breast cancer. Therefore, there is a significant interest in the development of compounds that may provide therapeutic benefit for hormone-independent breast cancer without untoward risks and adverse effects. The estrogen receptor (ER) modulators with both agonistic as well as antagonistic properties may, thus, be exploited for the development of the next generation of compounds for the prevention and/or treatment of breast cancer. In this article, we have discussed the clinical indications, risks, benefits and mechanisms of action of ER modulators and related compounds, particularly indole-3-carbinol (I3C), which may open new avenues for the prevention and/or treatment of breast cancer.