No abstract

Our findings indicate that metformin is effective at initiating apoptosis and inhibiting key survival signaling pathways in HCC cells. These data provide a foundation for further studies to evaluate metformin in the clinic either as a single agent or in combination with other first-line agents as a treatment option for HCC.

The objective of this study was to investigate the expression, proliferation, and apoptosis function of long-chain non-coding RNA maternally expressed gene 3 (MEG3) and antisense non-coding RNA at the INK4 locus (ANRIL) in gallbladder cancer (GBC) tissues. GBC tissues and adjacent normal samples were collected from 84 patients from January 2008 to June 2010. Empty vector, pcDNA-MEG3, and pcDNA-ANRIL vectors were transfected into GBC-SD and QBC939 cells. An MTT assay, real-time quantitative polymerase chain reaction (RT-qPCR), flow cytometry, Western blotting, and immunohistochemistry were applied. The effects of MEG3 and ANRIL were also verified in mice. Compared with normal tissues, the expression of MEG3 was significantly lower in GBC tissues, whereas the expression of ANRIL was significantly higher (both P < 0.05). The overexpression of MEG3 and underexpression of ANRIL were significantly associated with GBC prognosis (both P < 0.05). The expressions of MEG3 and ANRIL were higher in pcDNA-MEG3 and pcDNA-ANRIL-transfected cells than in empty vector-transfected cells in vitro (both P < 0.05). Most of the pcDNA-MEG3-transfected cells were in the G0-G1 phase, which showed reduced cell activity and clone counts and increased p53 and decreased cyclin D1, whereas the pcDNA-ANRIL-transfected cells were mostly in the S phase and showed contrasting behavior. Mice injected with pcDNA-MEG3-transfected cells had smaller and lighter tumors, decreased ki-67 levels, and increased caspase 3 levels, whereas those injected with pcDNA-ANRIL showed contrasting results (all P < 0.05). MEG3 can inhibit the proliferation of GBC cells and promote apoptosis, whereas ANRIL can improve the proliferation of gallbladder cells and inhibit apoptosis. Collectively, our results suggest that therapeutic strategies directed toward upregulating MEG3 and downregulating ANRIL may be clinically relevant for the inhibition of GBC deterioration.

Overexpressions of EphA2 and MMP-9 relate to tumor progression, metastasis, and prognosis in HCC. The present study suggests that EphA2 is associated with key mediators of angiogenesis and invasion.

BackgroundGlycochenodeoxycholate (GCDA) is one of the major human bile salts. Bile salts stimulate cell survival and proliferation through the mitogen-activated protein kinase, but the downstream signaling mechanism(s) remains enigmatic. Mcl-1 is an antiapoptotic molecule of the Bcl2 family that is extensively overexpressed in tumor tissues of patients with hepatocellular carcinoma (HCC).ResultsHere we found that exposure of HepG2 cells to GCDA results in activation of ERK1 and ERK2 and phosphorylation of Mcl-1 in a PD98059 (MEK inhibitor)-sensitive manner. GCDA stimulates Mcl-1 phosphorylation in cells expressing WT but not T163A Mcl-1 mutant, indicating that GCDA-induced Mcl-1 phosphorylation occurs exclusively at the T163 site in its PEST region. GCDA-induced Mcl-1 phosphorylation at T163 enhances the half-life of Mcl-1. Treatment of HepG2 cells with GCDA facilitates Mcl-1 dissociation from Mule (a physiological Mcl-1 ubiquitin E3 ligase). Specific depletion of Mcl-1 from HepG2 cells by RNA interference increases sensitivity of HepG2 cells to chemotherapeutic drugs (i.e. cisplatin and irinotecan). In addition to activation of the ERK/Mcl-1 survival pathway, GCDA can also induce dose-dependent apurinic/apyrimidinic (AP) sites of DNA lesions, which may partially neutralize its survival activity.ConclusionOur findings suggest that bile salt may function as a survival agonist and/or potential carcinogen in the development of HCC. Molecular approaches that inactivate Mcl-1 by blocking its T163 phosphorylation may represent new strategies for treatment of HCC.