Dihydroartemisinin induces apoptosis preferentially via a Bim-mediated intrinsic pathway in hepatocarcinoma cells

Abstract

This report is designed to dissect the detail molecular mechanism by which dihydroartemisinin (DHA), a derivative of artemisinin, induces apoptosis in human hepatocellular carcinoma (HCC) cells. DHA induced a loss of the mitochondrial transmemberane potential (ΔΨm), release of cytochrome c, activation of caspases, and externalization of phosphatidylserine indicative of apoptosis induction. Compared with the modest inhibitory effects of silencing Bax, silencing Bak largely prevented DHA-induced ΔΨm collapse and apoptosis though DHA induced a commensurable activation of Bax and Bak, demonstrating a key role of the Bak-mediated intrinsic apoptosis pathway. DHA did not induce Bid cleavage and translocation from cytoplasm to mitochondria and had little effects on the expressions of Puma and Noxa, but did increase Bim and Bak expressions and decrease Mcl-1 expression. Furthermore, the cytotoxicity of DHA was remarkably reduced by silencing Bim, and modestly but significantly reduced by silencing Puma or Noxa. Silencing Bim or Noxa preferentially reduced DHA-induced Bak activation, while silencing Puma preferentially reduced DHA-induced Bax activation, demonstrating that Bim and to a lesser extent Noxa act as upstream mediators to trigger the Bak-mediated intrinsic apoptosis pathway. In addition, silencing Mcl-1 enhanced DHA-induced Bak activation and apoptosis. Taken together, our data demonstrate a crucial role of Bim in preferentially regulating the Bak/Mcl-1 rheostat to mediate DHA-induced apoptosis in HCC cells.

Dihydroartemisinin induces apoptosis and autophagy‐dependent cell death in cholangiocarcinoma through a DAPK1‐BECLIN1 pathway

“…In parallel, DHA induced the expression of several autophagy‐related genes, including ATG12, BNIP3, and ULK1, and lowered the expression of mTOR, which normally represses autophagy. These data are in agreement with the reported ability of DHA to induce both apoptosis and autophagy in cancer cells. More than that, our study unravels a novel pathway through which DHA elicits its toxic effect.…”

Artesunate induces apoptosis via a ROS-independent and Bax-mediated intrinsic pathway in HepG2 cells

“…However, it is unclear whether the normal p53 and retinoblastoma genes play a role in ARS-induced ROS-independent apoptosis pathway in HepG2 cells. Although drug sensitivity may correlate to the status of p53 [38], the same proapoptotic drug can induce apoptosis via p53-dependent and/or p53-independent pathways [21,39,40]. In addition, differences in the expression of drug metabolizing enzymes among these cell lines may also contribute to their different ARS response [41].…”

“…To verify whether HepG2 cells are resistant to ROS, we assessed the role of ROS in DHA-induced apoptosis in this cell line, and found that DHA induced a ROS-dependent apoptosis [40], indicating the controversial regulation mechanisms by which ARTs induce apoptosis in this cell line, and this discrepancy may be due to the different metabolic products from iron-ARS/DHA reactions. Moreover, we found that in other two HCC cell lines (Huh-7 and Hep3B), even though ARS induced a lower rate of ROS generation (data not shown), ARS induced a ROS-dependent apoptosis (Fig.…”

Artemisinin as an anticancer drug: Recent advances in target profiling and mechanisms of action

“…Artemisinin is frequently reported to induce apoptosis by the intrinsic mitochondrial pathway, mediated by caspase 3/9 activation and the release of cytochrome C following the permeabilization of the mitochondrial membrane . This form of artemisinin‐induced cell death can be affected by the manipulation of antiapoptotic proteins such as Bcl‐2, as well as proapoptotic factors such as Bid and Bak . Outside of the intrinsic pathway, the extrinsic/death receptor driven pathway has also been implicated in the action of artemisinin .…”