No abstract

Lung cancer remains a deadly disease with unsatisfactory overall survival. Resveratrol (Res) has the potential to inhibit growth of several types of cancer such as prostate and colorectal examples. In the current study, we evaluated in vitro and in vivo anticancer efficiency of Res in a xenograft model with A549 cells. Cell inhibition effects of Res were measured by MTT assay. Apoptotis of A549 cells was assessed with reference to caspase-3 activity and growth curves of tumor volume and bodyweight of the mice were measured every two days. In vitro cytotoxicity evaluation indicated Res to exert dose-dependent cell inhibition effects against A549 cells with activation of caspase-3. In vivo evaluation showed Res to effectively inhibit the growth of lung cancer in a dosedependent manner in nude mice. Therefore, we believe that Res might be a promising phytomedicine for cancer therapy and further efforts are needed to explore this potential therapeutic strategy.

Abstract. Cantharidin is a terpenoid isolated from Chinese blister beetles, and norcantharidin (NCTD) is a demethylated analog of cantharidin. It has been reported that cantharidin and norcantharidin have anticancer activities. Growing evidence suggests that inhibiting autophagy can induce apoptosis in the human hepatoma cell line HepG2. The objective of the present study was to determine whether inhibition of autophagy enhances NCTD-induced apoptosis in HepG2 cells. HepG2 cells were cultured in DMEM containing NCTD. Autophagy was upregulated in the presence of HBSS media supplemented with Ca 2+ and Mg 2+ and 10 mM HEPES and downregulated in the presence of 3-methyladenine (3-MA) and Atg5 siRNA. Autophagy, cell viability, and the expression of apoptotic proteins were assessed in HepG2 cells. Our data showed that cell apoptosis generally increased after norcantharidin treatment in HepG2 cells. Expression of LC3-II, an autophagosome marker, increased when cells were treated with HBSS media. It also increased cell viability. However, in the presence of 3-MA and Atg5 siRNA, autophagy was inhibited, LC3-II expression decreased and cell apoptosis increased. There was increased expression of Bax, cytochrome c, cleaved caspase-3, caspase-9 and PARP and the mitochondrial membrane potential was disrupted. Additionally, increased apoptosis was accompanied by increased reactive oxygen species (ROS) production. NCTD has anticancer activity, and Atg5 siRNA-mediated downregulation of autophagy enhanced its anticancer actions due to ROS generation and activation of the mitochondrial apoptosis pathway. IntroductionLiver cancer is the sixth most frequent cancer and the second leading cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) represents 90% of all primary liver cancers (1-3). The 5-year survival rate for HCC is <30% and the recurrence rate is ~70% (4,5). Current HCC treatments, including surgical resection, liver transplantation, chemotherapy, or immuno-biological cancer therapies, are typically not very effective.Cantharidin is a terpenoid isolated from Chinese blister beetles, and norcantharidin (NCTD) is a demethylated analog of cantharidin that has anticancer activity in breast cancer, lung cancer, leukemia, colon and liver cancer. One possible explanation for the anticancer actions of NCTD is its inhibition of protein phosphatases, through which G0/G1 or G2/M arrest is triggered. Thus, apoptosis is subsequently induced via ROS generation and the mitochondrial pathway (6,7).Autophagy, an important pathophysiological process, is crucial for cell development, differentiation, survival and homeostasis. Additionally, autophagy has an important role in liver cancer. Previous studies have shown that autophagy is induced in liver cancer.

Cinobufagin is a cardiotoxic bufanolide steroid secreted by the Asiatic toad Bufo gargarizans. Cinobufagin is one of the active ingredients in the anticancer Chinese medicine called Chan Su, which was demonstrated to be an effective treatment for gastric cancer. Increasing evidence shows that inhibition of autophagy has a pro-apoptotic effect on human gastric cancer cells. The aim of the present study was to investigate the relationship between cinobufagin, autophagy and apoptosis in gastric cancer. Autophagy was induced or inhibited in the human gastric cancer cell line SGC-7901 by incubation in HBSS media or by treatment with 3-methyladenine or ATG5 siRNA, respectively. Following treatment, the levels of apoptosis, apoptotic proteins, reactive oxygen species (ROS), and mitochondrial membrane potential were compared between the conditions. As anticipated, we found that cinobufagin increased apoptosis in SGC-7901 cells. Notably, inhibition of autophagy, monitored by the absence of the autophagosome marker LC3-II, also enhanced cell apoptosis. This effect was reversed when autophagy was induced by incubation in HBSS media. Enhanced expression of pro-apoptotic indicators, including BAX, cytosolic cytochrome c, cleaved PARP, caspase-3 and caspase-9, was detected when autophagy was suppressed. Increased pro-apoptotic protein expression was accompanied by disrupted mitochondrial membrane potential and elevated ROS production. Altogether, these data suggest that inhibition of autophagy enhances the anticancer action of cinobufagin through increased apoptosis of gastric cancer cells. Moreover, these effects may be partly mediated by ROS generation and the activation of the mitochondrial programmed cell death pathway.