Resveratrol induces colon tumor cell apoptosis independently of p53 and precede by epithelial differentiation, mitochondrial proliferation and membrane potential collapse

Abstract

Resveratrol, a polyphenol present in wine and grapes, can inhibit tumor cell growth in vitro and tumorigenesis in vivo. Some of its effects have been linked to activation of the p53 tumor suppressor; however, p53 is frequently mutated in tumors, particularly in the common and often therapy-resistant colon cancers. Using the human wild-type p53-expressing HCT116 colon carcinoma cell line and HCT116 cells with both p53 alleles inactivated by homologous recombination, we show in the current study that resveratrol at concentrations comparable to those found in some foods can induce apoptosis independently of p53. The cell death is primarily mitochondria-mediated and not receptor-mediated. No cells survived in cultures continuously exposed to 100 M resveratrol for 120 hr. When compared with 5-FU, resveratrol stimulated p53 accumulation and activity only weakly and with delayed kinetics and neither the increased levels nor the activity affected apoptosis detectably. The apoptosis agonist Bax was overproduced in response to resveratrol regardless of p53 status, yet the kinetics of Bax expression were influenced by p53. Remarkably, apoptosis was preceded by mitochondrial proliferation and signs of epithelial differentiation. Thus, resveratrol triggers a p53-independent apoptotic pathway in HCT116 cells that may be linked to differentiation. The antifungal phytoalexin resveratrol (3,5,4Ј-trihydroxy-transstilbene) is a constituent of many plant species and present at particularly high levels in grapes and wine. 1 As a polyphenol, it is not only a potent inhibitor of radical formation (ED 50 27 M) but acts as a pleiotropic effector molecule to inhibit initiation, promotion and progression of malignant transformation. Resveratrol inhibits the cyclooxygenase (ED 50 15 M) and hydroperoxidase (ED 50 3.7 M) activities of COX-1 and the hydroperoxidase activity of COX-2 (ED 50 85 M). 2 Furthermore, it functions as an inhibitor of platelet aggregation, a modulator of lipid and lipoprotein metabolism 3 and an effective blocker of ribonucleotide reductase (ED 50 100 M) that provides deoxyribonucleotides for DNA synthesis. 4 It also inhibits DNA polymerase 5 and mimics estradiol. 6 Several of these activities constitute the basis for the chemopreventive action of resveratrol, exemplified by its antimutagenic activity in the Ames assay, inhibition of tumorigenesis in a 2-stage murine skin-cancer model 2 and inhibition of cell proliferation in vitro. 7,8 The presence of the functional wild-type form of the p53 tumor suppressor correlates with the sensitivity of mouse tumors and at least some human tumors to therapeutic agents. 9 -11 p53 is stabilized and activated as a transcription factor in response to a variety of cellular stresses, 12 the result being either cell-cycle arrest, mostly through transcriptional activation of the p21 WAF/Cip1 inhibitor of cyclin-dependent kinases, or apoptosis, depending on the cell context. Apoptosis often involves changes to mitochondria. 13 One of the major predictive parameters indicating commitment...

Resveratrol Induces p53-independent, X-linked Inhibitor of Apoptosis Protein (XIAP)-mediated Bax Protein Oligomerization on Mitochondria to Initiate Cytochrome c Release and Caspase Activation

“…These findings are consistent with the earlier report that resveratrol induces p53-independent apoptosis in cancer cells (65,67,(73)(74)(75)(76). Although Bak can be activated by p53 (59), we did not observe p53 involvement in Bak activation.…”

“…Similarly, Western blot analysis clearly demonstrated caspase-9 activation but not caspase-8 activation in MDA-MB231 cells, suggesting that caspase-9 is the initiator caspase for caspase-dependent apoptosis in response to resveratrol in cancer cells (data not shown). Our results are consistent with previous findings that resveratrol induces mitochondrion-dependent but death receptor-independent apoptosis (65,66). Because resveratrol primarily targets mitochondria to induce apoptosis, resveratrol could be used as a synergistic agent to enhance death receptor-mediated cancer cell death.…”

Gene network analysis of oxidative stress-mediated drug sensitivity in resistant ovarian carcinoma cells

“…42,43 Although p53 is predominantly a nuclear protein, it also travels from the nucleus to the mitochondria in response to death stress. 44 Moreover, it seems that, in dividing Cbl cos cells, DNA-PKc is more in the nucleus than in the cytoplasm, whereas in dying cells (in which the nucleus appears fragmented, a sign of late-stage apoptosis), it is present more in the cytoplasm (data not shown). The much lesser expression of cyclin-dependant kinase, CDK6, in Cbl cos cells also justifies apoptotic signaling in these cells.…”

Resveratrol-induced Apoptosis Is Associated with Fas Redistribution in the Rafts and the Formation of a Death-inducing Signaling Complex in Colon Cancer Cells

“…The caspases involved in the death process and the pathways leading to their activation could differ from one cell type to another. For example, resveratrol has been documented to activate the transcription factor p53, which was proposed to contribute to death (45,46), but the polyphenol also induces apoptosis in p53-deficient cells (47,48), indicating that p53 is not an absolute requirement for the cytotoxic effect of the molecule. According to caspases, resveratrol-induced apoptosis appears to converge on caspase-9 and downstream caspase-3 activation, suggesting a mitochondrialand cytochrome c-mediated mechanism.…”