Mitochondria, Calcium, and Calpain are Key Mediators of Resveratrol-Induced Apoptosis in Breast Cancer

Abstract

Resveratrol (RES), a natural plant polyphenol, has gained interest as a nontoxic chemopreventive agent capable of inducing tumor cell death in a variety of cancer types. However, the early molecular mechanisms of RES-induced apoptosis are not well defined. Using the human breast cancer cell lines MDA-MB-231 and MCF-7, we demonstrate that RES is antiproliferative and induces apoptosis in a concentration-and time-dependent manner. Preceding apoptosis, RES instigates a rapid dissipation of mitochondrial membrane potential by directly targeting mitochondria. This is followed by release of cytochrome c and second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) into the cytoplasm and substantial increase in the activities of caspases-9 and -3 in MDA-MB-231 cells. In addition, live cell microscopy demonstrates that RES causes an early biphasic increase in the concentration of free intracellular calcium ([Ca 2ϩ ] i ), probably resulting from depletion of the endoplasmic reticulum stores in breast cancer cells. In caspase-3-deficient MCF-7 cells, apoptosis is mediated by the Ca 2ϩ -activated protease, calpain, leading to the degradation of plasma membrane Ca 2ϩ -ATPase isoform 1 and fodrin; the degradation is attenuated by buffering [Ca 2ϩ ] i and blocked by calpain inhibitors. Mitochondrial permeability transition pore antagonists also blocked calpain activation. In vivo mouse xenograft studies demonstrate that RES treatment inhibits breast cancer growth with no systemic toxicities. Together, these results suggest a critical role for mitochondria not only in the intrinsic apoptotic pathway but also in the Ca 2ϩ and calpain-dependent cell death initiated by RES. Thus, RES may prove useful as a nontoxic alternative for breast cancer treatment.

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“…Further, CaSR knockdown decreases proliferation and bone metastasis of prostate cancer cells (59). In contrast to the aforementioned findings, other studies have reported a role for rise in cytosolic Ca 2ϩ levels in cancer cell apoptosis (88). Sareen et al (88) showed that resveratrol induces breast cancer cell apoptosis via Ca 2ϩ -dependent activation of calpain protease.…”

Resveratrol: A multitargeted agent for age-associated chronic diseases

“…Recently it has been shown with the help of live cell microscopy that resveratrol causes an early biphasic increase in the concentration of free intracellular calcium [(Ca +2 )i] levels, which may result from the depletion of the endoplasmic reticulum stores in breast cancer cells. 34 The apoptosis is mediated by a mitochondrial-dependent pathway and calpain, a Ca +2 regulated protein, which also plays a role in the resveratrol-mediated apoptosis in MCF-7 cells. 34 Tang et al 35 reported that resveratrol induces nuclear accumulation of COX-2 protein in human breast cancer MCF-7 and MDA-MB-231 cell cultures, a process dependent on MAPK ½, and AP-1 eventually results in a p53-mediated apoptosis.…”

“…34 The apoptosis is mediated by a mitochondrial-dependent pathway and calpain, a Ca +2 regulated protein, which also plays a role in the resveratrol-mediated apoptosis in MCF-7 cells. 34 Tang et al 35 reported that resveratrol induces nuclear accumulation of COX-2 protein in human breast cancer MCF-7 and MDA-MB-231 cell cultures, a process dependent on MAPK ½, and AP-1 eventually results in a p53-mediated apoptosis. The compound also decreases the telomerase activity in vitro.…”

The Human Host Defense Peptide LL-37 Induces Apoptosis in a Calpain- and Apoptosis-Inducing Factor–Dependent Manner Involving Bax Activity

“…Other cytosolic cysteine proteases, known as calpain I and calpain II, require intracellular calcium (Ca 2+ ) for activation, and may trigger apoptosis and necrosis through the proteolysis of cellular substrates, including cytoskeletal and membrane proteins (17)(18)(19). Calpains can also activate proapoptotic Bcl-2 family members, resulting in outer mitochondrial membrane permeabilization and the release of proapoptotic proteins into the cytosol (see refs.…”