Resveratrol‐induced apoptosis in MCF‐7 human breast cancer cells involves a caspase‐independent mechanism with downregulation of Bcl‐2 and NF‐κB

Abstract

Resveratrol (RES), a chemopreventive molecule, inhibits the proliferation of tumor cells of different etiologies. We previously showed that RES alters the cell cycle and induces apoptosis in MCF-7 breast tumor cells by interfering with the estrogen receptor (ERa)-dependent phosphoinositide 3-kinase (PI3K) pathway. Here, we analyzed signaling downstream of PI3K, to understand the mechanisms of RES-induced apoptosis. Apoptotic death by RES in MCF-7 was mediated by Bcl-2 downregulation since overexpression of this protein abolished apoptosis. Decreased Bcl-2 levels were not related to cytochrome c release, activation of caspases 3/8 or poly(ADP-ribose) polymerase proteolysis. However, RES decreased mitochondrial membrane potential and increased reactive oxygen species and nitric oxide production. NF-kB, a regulator of Bcl-2 expression, and calpain protease activity, a regulator of NF-kB, were both inhibited by RES. The patterns for NFkB and calpain activities followed that of PI3K and were inhibited by LY294002. NF-kB inhibition coincided with diminished MMP-9 activity and cell migration. These data suggest that RES-induced apoptosis in MCF-7 could involve an oxidative, caspase-independent mechanism, whereby inhibition of PI3K signaling converges to Bcl-2 through NF-kB and calpain protease activity. Therefore, Bcl-2 and NF-kB could be considered potential targets for the chemopreventive activity of RES in estrogen-responsive tumor cells. ' 2005 Wiley-Liss, Inc.Key words: resveratrol; caspase; Bcl-2; NF-kB; apoptosis Among natural compounds with beneficial effects on human health, RES (3,4 0 ,5-trihydroxystilbene) has attracted considerable interest. This molecule, present at relevant concentrations in red wine, 1 has been associated with a lower incidence of cardiovascular disease. Different studies have also suggested a beneficial effect of RES in cancer since it inhibits proliferation and promotes death in tumor cell lines of different origins, 2-4 and, in vivo, suppresses the formation of skin 5 and mammary gland 6 tumors in rodent models of carcinogenesis.We, as well as other laboratories, have found that the ability of RES to inhibit cell viability and proliferation in the human breast cancer cell lines MCF-7 and MDA-MB-231 was unrelated to ERa status. 7,8 However, apoptotic cell death was present only in ERapositive MCF-7 and involved cell-specific regulation of the G 1 /S and G 2 /M transitions of the cell cycle. 2,8 RES properties are related to ERa since this compound has estrogenic or antiestrogenic activities depending on its concentration and the phenotype of the target cell. 9,10 ERa, in addition to its nuclear role as a transcription factor, is involved in regulating the PI3K pathway, which controls cell growth, proliferation and apoptosis. [11][12][13] In MCF-7 cells, RES induced a biphasic pattern of PI3K activity that increased at low concentrations and decreased at high concentrations. Activation of downstream PI3K effectors PKB/AKT and GSK-3 closely followed the pattern of PI3K activity. 14 The ...

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Caspase-2 Triggers Bax-Bak-dependent and -independent Cell Death in Colon Cancer Cells Treated with Resveratrol

“…Resveratrol has been reported to induce caspase activation subsequent to mitochondrial release of cytochrome c (2,4,21), caspase activation independent of cytochrome c release (25), caspase-8-mediated Bax/Bak-dependent cell death (28), p53-or Bax-dependent and -independent cell death (26), ceramide-mediated cell cycle arrest and apoptosis (42), and death receptor (CD95)-dependent death signaling (38). Multiple and diverging death signaling events, all converging to apoptosis in different cells, suggest that resveratrol-induced cell death varies from cell to cell, indicating a possible role for regulatory molecules of apoptosis that govern the apoptotic threshold of a cell.…”

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“…169 Other chemoprotective effects by resveratrol are mediated through activation of p53 via ERK and p38 kinase, inhibition of inflammatory mediators, and downregulation of Bcl-2 and NFB. 170,171 These properties of resveratrol directly oppose the purported cardioprotective benefits. For example, activation of the PI3-K signaling cascade and protection against apoptosis by 17␤-estradiol proves protective in cardiac myocytes.…”

“…However, studies show that resveratrol can impart antiproliferative effects that result from apoptosis in MCF-7 but not in MDA-MB-231 human breast cancer cells. 171 Thus, there is apparently some tissue specificity of resveratrol action. Moreover, resveratrol can act as mixed antagonist/ agonist depending on concentration, like other estrogenic counterparts.…”