Indole-3-Carbinol (I3C) Induces Apoptosis in Tumorigenic but Not in Nontumorigenic Breast Epithelial Cells

Abstract

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.

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

“…I3C (Sigma-Aldrich, St. Louis, MO) was dissolved in DMSO (final concentration, 0.1%) to make a 10 mmol/L stock solution and was added directly to the culture medium at different concentrations. Nuclear extracts were prepared from control and I3C-treated breast epithelial cells as previously described (25,29,37) and subjected to analysis for NF-nB DNA-binding activity as measured by electrophoretic mobility shift assay. Using frozen tumor tissue, nuclear proteins were also extracted as described previously (25,29,37).…”

“…Nuclear extracts were prepared from control and I3C-treated breast epithelial cells as previously described (25,29,37) and subjected to analysis for NF-nB DNA-binding activity as measured by electrophoretic mobility shift assay. Using frozen tumor tissue, nuclear proteins were also extracted as described previously (25,29,37). Briefly, tissues were minced and incubated on ice for 30 minutes in 0.5 mL ice-cold buffer A composed of 10 mmol/L HEPES (pH 7.9), 1.5 mmol/L KCl, 10 mmol/L MgCl 2 , 0.5 mmol/L DTT, 10% NP40, 0.1% IGEPAL CA-630, and 0.5 mmol/L phenylmethylsulfonyl fluoride.…”

“…Control cells were incubated in the medium with DMSO for similar times. Total cell lysates were prepared using the method as described previously (25,29,37). Using frozen tumor tissue, nuclear proteins were extracted using the method as described previously (25,29,37).…”

BRCA1 and BRCA2 as molecular targets for phytochemicals indole-3-carbinol and genistein in breast and prostate cancer cells

“…Cytotoxicity At high doses (X100 mM), I3C causes cytotoxicity and apoptosis in cancer cell lines (Chen et al, 2001;Chinni et al, 2001;Rahman et al, 2003;Sarkar et al, 2003). Exogenous BRCA1 causes increased susceptibility to apoptosis due to DNA-damaging agents (e.g., adriamycin), although wtBRCA1 does not induce apoptosis by itself (Fan et al, , 2001b.…”

The balance of estrogen metabolites in breast cancer and the ways of its correction

“…Многочисленные исследования последних лет по-священы фитонутриентам -веществам растительного происхождения, терапевтические концентрации не-которых из них оказывают поразительный эффект, связанный с избирательным ингибированием роста опухолевых клеток, индукцией их апоптоза [11,12].…”