Hepatocellular carcinoma (HCC) is one of the most common solid cancers, representing the third cause of cancer-related death among cirrhotic patients. Treatment of advanced HCC has become a very active area of research. Perifosine, a new synthetic alkylphospholipid Akt inhibitor, has shown anti-tumor activity by inhibition of Akt phosphorylation. In this study, the effect of perifosine on the cell proliferation and apoptosis in hepatoma cells has been investigated. Cell growth inhibition was detected by MTT assay, cell cycle was analyzed by flow cytometry, AnnexinV-FITC apoptosis detection kit was used to detect cell apoptosis, and protein expression was examined by Western blotting analysis. Our present studies showed that Akt phosphorylation was inhibited by perifosine in HepG2 and Bel-7402 human hepatocellular carcinoma cells. Perifosine inhibited the growth of HepG2 cells and Bel-7402 cells in a dose-dependent manner, and arrested cell cycle progression at the G(2) phase. Apoptosis induction became more effective with increasing perifosine concentration. The caspase cascade and its downstream effectors, Poly (ADP-ribose) polymerase (PARP), were also activated simultaneously upon perifosine treatment. The proapoptotic effect of perifosine was in part depending on regulation of the phosphorylation level of ERK and JNK. Perifosine cotreatment substantially increased cytotoxic effects of cisplatin in HepG2 cells. Down-regulating the expression of Bcl-2 and up-regulating the level of Bax may be the potential mechanism for this synergistic effect. Our findings suggest that the small molecule Akt inhibitor perifosine shows substantial anti-tumor activity in human hepatoma cancer cell lines, and is a good candidate for treatment combinations with classical cytostatic compounds in hepatocellular carcinoma.

Hepatitis B x-interacting protein (HBXIP), a co-factor of survivin, was originally identified by its binding with the C-terminus of the hepatitis B virus x protein (HBx). We have recently shown that HBXIP promotes the growth of both normal liver cells and hepatoma cells in vitro, but the molecular mechanisms of this have not been documented. In this study, we investigated the potential effects of HBXIP on the proliferation of HepG2 cells and the intracellular signaling pathway mediating these changes. Over-expression of the HBXIP gene promoted the proliferation of HepG2 cells, as shown by the MTT assay. We also showed that HBXIP induced cellular accumulation in the S phase concomitantly with up-regulation of cyclinD(1) and down-regulation of p21 and p53 levels. Moreover, HBXIP over-expression cells showed activation of the PI3K/Akt pathway; this activation was accompanied by an increase in phosphorylation of glycogen synthase kinase 3β. LY294002, a specific inhibitor of PI3K, blocked HBXIP-stimulated Akt phosphorylation and suppressed the cell cycle promotion induced by HBXIP in HepG2 cells. The increase in cyclinD(1) protein levels induced by HBXIP was inhibited when cells were incubated with LY294002. In conclusion, our data suggest that the proliferation of HepG2 cells promoted by HBXIP is associated with activation of the PI3K/Akt signaling pathway.

Chemotherapy- or radiotherapy-induced DNA damage activates the Chk1-dependent DNA damage response (DDR) and cell cycle checkpoints to facilitate cell survival. Numerous attempts have been made to identify specific Chk1 inhibitors to enhance the efficiency of chemotherapy or radiotherapy. In this study, we investigated the molecular mechanisms underlying the antitumor activity of LY2603618, a potent and selective small molecule inhibitor of Chk1 protein kinase, in human lung cancer cells. Treatment of cancer cells with LY2603618 caused cell cycle arrest in the G2/M phase. A marked induction of DDR, including the phosphorylation of ATM, Chk2, p53 and histone H2AX, was observed after LY2603618 treatment. LY2603618 inhibited Chk1 autophosphorylation (S296 Chk1) and increased DNA damage-mediated Chk1 phosphorylation (S345 Chk1). In addition, LY2603618-treated lung cancer cells transitioned from LC3-I to LC3-II, a hallmark of autophagy. Blocking autophagy with chloroquine (CQ) further enhanced LY2603618's inhibitory effect on cell viability/proliferation. LY2603618 also significantly increased p38 and c-Jun N-terminal kinase (JNK) phosphorylation. Pretreatment with the JNK inhibitor reduced cleavage of caspase-3 and PARP levels in LY2603618-treated cells. These results suggest the following: (i) the biological consequences of LY2603618 in lung cancer cells is associated with both inhibition of Chk1 phosphorylation on S296 and activation of the DNA damage response network; and (ii) the anticancer property of LY2603618 might be increased by inhibiting autophagy.

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In this study, we investigate the anti-cancer activity of caudatin in carcinomic human alveolar basal epithelial cell line A549 and anti-angiogenic activity in human umbilical vein endothelial cells (HUVECs). We show that caudatin impairs the cell viability and induces G(0) /G(1) phase arrest in A549 cells with a dose dependent manner. A549 cells, not HUVECs, dealing with caudatin exhibited typical characteristics of apoptosis, which were accompanied by activation of caspase-3, caspase-9 and Poly(ADP-Ribose) Polymerase (PARP). In addition, caudatin treatment resulted in a decrease of β-catenin and increase of phosphorylation of β-catenin, and inhibited phosphorylation levels of GSK3β (Ser 9) in A549 cells. Conditional medium of A549 cells-induced or growth factors-induced tube formation of HUVECs was markedly inhibited by caudatin treatment, which was associated with the inhibiting VEGF secretion from A549 cells by caudatin. Our findings suggest that caudatin inhibits carcinomic human alveolar basal epithelial cell growth and angiogenesis by targeting GSK3β/β-catenin pathway and suppressing VEGF production.