Aspirin reduces the apoptotic effect of etoposide via Akt activation and up-regulation of p21cip

Abstract

Abstract. Previous studies on the apoptotic effect of aspirin mainly focus on colorectal cancer and breast carcinoma. Few studies have been designed to explore the effect of aspirin on hepatocellular carcinoma. In the present study, we observed that aspirin caused G0/G1 phase cell cycle arrest and reduced etoposide induced caspase-3 activation in hepatocellular carcinoma G2 (HepG2) cells. Further investigation demonstrated that aspirin notably enhanced the activity of Akt and ERK1/2. Blocking the activation of Akt by the PI3-K-selective inhibitor wortmannin abrogated the anti-apoptotic effect of aspirin while the MEK inhibitor U0126 did not. p21 cip , an important substrate of Akt, is involved in the regulation of cell cycle arrest and apoptosis. Our data showed that the protein expression and ser146 phosphorylation levels of p21 cip were significantly increased after treatment with aspirin, whereas p53 or p27 showed no change. The increase of p21 cip protein levels was also scavenged by wortmannin but not by U0126. Moreover, reduction of caspase-3 activity induced by aspirin was attenuated by silencing p21 cip expression. These results indicated that the anti-apoptotic effect of aspirin was dependent on activation of Akt which inhibited cell apoptosis by up-regulating p21 cip and blocking caspase-3 activation. These findings could have clinical relevance in anticancer therapy and aspirin co-treatment of human malignancies.

AMPK-mediated up-regulation of mTORC2 and MCL-1 compromises the anti-cancer effects of aspirin

“…Inhibition of COX2, one of the targets of aspirin, reportedly inhibits PI3K/Akt kinase activity in epithelial ovarian cancer [ 33 ]. Consistent with the current study, Feng and collegues reported that aspirin could induce Akt and ERK1/2 phosphorylation in HepG2 cells [ 34 ]. Our current study demonstrates that activation of AMPK contributes to the induction of Akt phosphorylation by aspirin.…”