P62 Regulates resveratrol-mediated Fas/Cav-1 complex formation and transition from autophagy to apoptosis

Abstract

Resveratrol is a potential polyphenol drug used in cancer treatment. We examined the relationship between autophagy and apoptosis in RSV-treated non-small lung adenocarcinoma A549 cells. Resveratrol treatment increased autophagy and autophagy-mediated degradation of P62. Immunocytochemistry revealed P62 co-localized with Fas/Cav-1 complexes, known to induce apoptosis. However, siRNA-mediated P62 downregulation enhanced formation of Fas/Cav-1 complexes, suggesting that P62 inhibited Fas/Cav-1 complex formation. Fas/Cav-1 complexes triggered caspase-8 activation and cleavage of Beclin-1, releasing a C-terminal Beclin-1 peptide that translocated to the mitochondria and initiate apoptosis. Inhibition of autophagy by siRNA-mediated repression of Beclin-1 also blocked RSV-induced apoptosis, showing a dependence of apoptosis on autophagy. P62 knockdown by siRNA accelerated the activation of caspase-8 and initiate apoptosis, while Cav-1 knockdown inhibited apoptosis, but increased autophagy. Inhibition of autophagy by 3-MA prevented both P62 degradation and induction of apoptosis, whereas inhibition of apoptosis by z-IETD-FMK or z-DEVD-FMK enhanced both P62 induction and autophagic cell death. In conclusion, P62 links resveratrol-induced autophagy to apoptosis. P62 blocks apoptosis by inhibiting Fas/Cav-1 complex formation, but RSV-induced autophagic degradation of P62 enables formation of Fas/Cav-1 complexes which then activate caspase-8-mediated Beclin-1 cleavage, resulting in translocation of the Beclin-1 C-terminal fragment to the mitochondria to initiate apoptosis.

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

“…To distinguish whether autophagosome accumulation was due to enhanced autophagic activity or reduced autophagosome degradation, the protein expression levels of p62 were determined in the present study. p62, an autophagy-related protein, is involved in the formation of autophagosomes and degraded through autophagy (19,20). The present results showed that the protein expression level of p62 was significantly decreased in Res-treated cells compared with the control.…”

“…The p62 protein acts as a signaling hub through its involvement in the formation of autophagosomes and is degraded during autophagy (19,20). The results indicated that p62 protein expression levels were decreased by Res in a time-dependent manner, suggesting an increase in autophagic flux (Fig.…”

“…In addition to LC3, the expression level of p62 protein, which is another autophagy-specific biomarker was also explored (19,20). The p62 protein acts as a signaling hub through its involvement in the formation of autophagosomes and is degraded during autophagy (19,20).…”

Caveolin-1 in the regulation of cell metabolism: a cancer perspective

“…The downregulation of Cav1 coincided with altered expression of several profibrotic genes, including upregulation of Tgfbr2 , Smad3 , Tgfb1 , Tgfb3 , and suppression of Smad4 , 7 and Snai1 [112], suggesting a link between its expression and fibrosis via autophagy. In non-small lung adenocarcinoma cells (A549), expression of CAV1 was protective by blocking a switch from autophagy to apoptosis [113]. Taken together, these studies show a context-dependent involvement of CAV1 in autophagy that requires further clarification, especially in cancer types where CAV1 is a key player.…”

Diosmetin inhibits cell proliferation and induces apoptosis by regulating autophagy via the mammalian target of rapamycin pathway in hepatocellular carcinoma HepG2 cells

“…Autophagy and apoptosis are important biological processes that maintain cell stability, structure, function and development (45). In the present study, autophagy was blocked by BA1 (41) to investigate whether DIOS-triggered apoptosis was affected.…”