Resveratrol depletes mitochondrial DNA and inhibition of autophagy enhances resveratrol-induced caspase activation

Abstract

We recently demonstrated that resveratrol induces caspase-dependent apoptosis in multiple cancer cell types. Whether apoptosis is also regulated by other cell death mechanisms such as autophagy is not clearly defined. Here we show that inhibition of autophagy enhanced resveratrol-induced caspase activation and apoptosis. Resveratrol inhibited colony formation and cell proliferation in multiple cancer cell types. Resveratrol treatment induced accumulation of LC3-II, which is a key marker for autophagy. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, increased resveratrol-mediated caspase activation and cell death in breast and colon cancer cells. Inhibition of autophagy by silencing key autophagy regulators such as ATG5 and Beclin-1 enhanced resveratrol-induced caspase activation. Mechanistic analysis revealed that Beclin-1 did not interact with proapoptotic proteins Bax and Bak; however, Beclin-1 was found to interact with p53 in the cytosol and mitochondria upon resveratrol treatment. Importantly, resveratrol depleted ATPase 8 gene, and thus, reduced mitochondrial DNA (mtDNA) content, suggesting that resveratrol induces damage to mtDNA causing accumulation of dysfunctional mitochondria triggering autophagy induction. Together, our findings indicate that induction of autophagy during resveratrol-induced apoptosis is an adaptive response.

Polyphenols as mitochondria-targeted anticancer drugs

“…MtDNA damage and a subsequent accumulation of dysfunctional mitochondria can induce not only apoptosis but also autophagy, an adaptive, pro-survival response aimed at removing the damaged mitochondria. After 24 h incubation of human breast cancer MDA-MB-231 cells with resveratrol, a decrease in mtDNA content was observed when compared with control cells [78]. The decrease could result from autophagy, triggered in the cells in response to mtDNA damage caused by the treatment with resveratrol.…”

Restoration of mitochondria function as a target for cancer therapy

“…Lipophilic cations, such as the intercalating anticancer drug ditercalinium, causes selective mtDNA depletion by inhibiting DNA polymerase gamma activity in cultured mammalian cells, which could be more selective than ethidium bromide because it differentially accumulates in the mitochondria [70]. It has been shown that resveratrol depletes mtDNA during apoptosis induction in cancer cells [71]. Additionally, cisplatin shows preferential binding with mtDNA compared with genomic DNA, causing impairment of mitochondrial function and cell death [72].…”

Resveratrol induces autophagic apoptosis via the lysosomal cathepsin D pathway in human drug‑resistant K562/ADM leukemia cells

“…It is known that beclin 1 generates a pro-apoptotic protein fragment and also interacts with the anti-apoptotic Bcl-2 family protein to inhibit autophagy and initiate mitochondrial apoptosis (22). Prabhu et al (25) reported that the silencing of key regulators of autophagy, such as beclin 1 and autophagy protein (ATG)5, significantly enhanced Res-induced caspase activation. In the present study, western blotting results revealed that Res significantly increased the expression levels of Bax and decreased those of Bcl-2.…”