Differences in antiproliferative effect of STAT3 inhibition in HCC cells with versus without HBV expression

Kahweol Induces Apoptosis in Hepatocellular Carcinoma Cells by Inhibiting the Src/mTOR/STAT3 Signaling Pathway

Kahweol, a coffee-specific diterpene, induces apoptosis in human cancer cells, and some targets of kahweol-mediated apoptosis have been identified. However, the specific apoptotic effects and mechanism of action of kahweol in hepatocellular carcinoma (HCC) cells are unknown. This study was performed to investigate the molecular mechanism by which kahweol induces apoptosis in HCC cells. The Src pathway is associated with apoptosis in cancer. In this study, we found that kahweol induces apoptosis by inhibiting phosphorylation of Src, and also inhibiting p-mTOR and p-STAT3. Therefore, we suggest that kahweol is a potent inhibitor of HCC cell growth.

EGF receptor inhibitors comprehensively suppress hepatitis B virus by downregulation of STAT3 phosphorylation

Current antiviral therapy can not cure chronic hepatitis B virus (HBV) infection or eliminate the risk of hepatocellular carcinoma. The licensed epidermal growth factor receptor (EGFR) inhibitors have found to inhibit hepatitis C virus replication via downregulation of signal transducers and activators of transcription 3 (STAT3) phosphorylation. Since STAT3 is also involved in HBV replication, we further studied the anti-HBV efficacy of the EGFR inhibitors in this study. HBV-transfected HepG2.2.15 cells and HBV-infected HepG2-NTCP cells were used as cell models, and HBV replication, the syntheses of viral antigens and the magnitude of the covalently closed circular DNA (cccDNA) reservoir were used as indictors to test the anti-HBV effects of EGFR inhibitors erlotinib and gefitinib. Erlotinib inhibited HBV replication with a half-maximal inhibitory concentration of 1.05 μM. It also reduced the syntheses of viral antigens at concentrations of 2.5 μM or higher. The underlying mechanism was possibly correlated with its inhibition on STAT3 phosphorylation via up-regulation of suppressor of cytokine signaling 3. Gefitinib also inhibited HBV replication and antigen syntheses. Compared with the commonest antiviral drug entecavir, these EGFR inhibitors additionally reduced hepatitis B e antigen and erlotinib also marginally affected the cccDNA reservoir in HBV-infected HepG2-NTCP cells. Interestingly, these promising anti-HBV effects were significantly enhanced by extension of treatment duration. In conclusion, EGFR inhibitors demonstrated a comprehensive anti-HBV potential, highlighting a new strategy to cure HBV infection and suggesting animal model-related studies or clinical try in the future.

Physagulide Q suppresses proliferation and induces apoptosis in human hepatocellular carcinoma cells by regulating the ROS-JAK2/Src-STAT3 signaling pathway

Physagulide Q (PQ), a new natural compound, was isolated from Physalis angulata L. in our laboratory.

Differential association of STAT3 and HK-II expression in hepatitis B virus- and hepatitis C virus-related hepatocellular carcinoma

STAT3 and hexokinase II (HK-II) are involved in viral infection and carcinogenesis of various cancers including hepatocellular carcinoma (HCC). The roles of STAT3 and HK-II in hepatitis B virus (HBV)- and hepatitis C virus (HCV)-related HCC remain largely unclear. This study examined STAT3 and HK-II expression in HBV- and HCV-related HCC, HBV-related liver fibrosis, and normal control liver by using tissue microarray and immunohistochemical method. Results showed that STAT3 expression in HBV-related HCC, HCV-related HCC, and HBV-related liver fibrosis was significantly higher than in control liver (P < 0.001, P = 0.016, and P = 0.005, respectively) and had no significant differences between these three diseased liver tissues. The HK-II expression in HBV-related HCC was significantly higher than that in HCV-related HCC, HBV-related liver fibrosis, and control liver (P = 0.007, P = 0.029, and P = 0.008, respectively) but had no significant elevation in and no significant differences between HCV-related HCC, HBV-related liver fibrosis, and control liver. The HK-II expression was significantly correlated to STAT3 expression in HBV-related HCC (P = 0.022), but no correlation was observed in HCV-related HCC, HBV-related liver fibrosis, and control liver. In conclusion, STAT3 expression is upregulated in both HBV- and HCV-related HCC, while HK-II is predominantly upregulated and correlated to STAT3 in HBV-related HCC. These differential expression and association may suggest the distinct roles of STAT3 and HK-II in hepatocarcinogenesis of HBV and HCV infection. Studies are needed to confirm the relationship of STAT3 and HK-II and to examine the underlying mechanisms. J. Med. Virol. 88:1552-1559, 2016. © 2016 Wiley Periodicals, Inc.

Apoptosis in liver carcinogenesis and chemotherapy

Hepatocellular carcinoma (HCC) is a major health problem. In human hepatocarcinogenesis, the balance between cell death and proliferation is deregulated, tipping the scales for a situation where antiapoptotic signals are overpowering the death-triggering stimuli. HCC cells harbor a wide variety of mutations that alter the regulation of apoptosis and hence the response to chemotherapeutical drugs, making them resistant to the proapoptotic signals. Considering all these modifications found in HCC cells, therapeutic approaches need to be carefully studied in order to specifically target the antiapoptotic signals. This review deals with the recent relevant contributions reporting molecular alterations for HCC that lead to a deregulation of apoptosis, as well as the challenge of death-inducing chemotherapeutics in current HCC treatment.