Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. The purpose of this study was to determine the effects of daucosterol on HCC by investigating Wnt/β-catenin signaling. In this study, HepG2 and SMMC-7721 cells were treated with varying concentrations of daucosterol, and the corresponding inhibitory effects on HCC cells were examined via CCK-8 assays. Cell migration and invasion abilities were detected via transwell assays. β-Catenin and phospho (p)-β-catenin levels were analyzed via western blotting. Our results showed that daucosterol reduced the proliferation, migration, and invasion capacities of HCC cells in a concentration-dependent manner. In addition, daucosterol reduced the levels of β-catenin and p-β-catenin in HepG2 and SMMC-7721 cells. Furthermore, the Wnt signaling pathway inhibitor SB-216763 was used to treat HepG2 and SMMC-7721 cells with daucosterol. Our results showed that co-treatment with daucosterol and SB-216763 abolished the effects of daucosterol on cell inhibition ratios, cell migration, and cell invasion. These findings indicated that daucosterol inhibited cell migration and invasion in HCC cells via the Wnt/β-catenin signaling pathway. Therefore, our study highlights the use of daucosterol as a promising therapeutic strategy for HCC treatment.
Background
HBV promotes cell survival by upregulating the expression of the cellular inhibitor of apoptosis protein 2 (cIAP2), however whether it is involved in HBV-induced sorafenib resistance in liver cancer remains unclear.
Methods
cIAP2 overexpression and knockdown was adopted to assess the involvement of cIAP2 in HBV-induced sorafenib resistance. Anti-HBV drug lamivudine and Akt inhibitor were used to investigate the impact of HBV replication on cIAP2 expression and sorafenib resistance. Xenotransplantation mouse model was used to confirm the data on cell lines in vitro.
Results
Liver cancer cell line HepG2.215 showed increased cIAP2 expression and enhanced resistance to sorafenib. Upon sorafenib treatment, overexpression of cIAP2 in HepG2 lead to decreased cleaved caspase 3 level and increased cell viability, while knockdown of cIAP2 in HepG2.215 resulted in increased level of cleaved caspase 3 and decreased cell viability, suggesting the involvement of cIAP2 in HBV-induced sorafenib resistance. Furthermore, anti-HBV treatment reduced cIAP2 expression and partially restored sorafenib sensitivity in HepG2.215 cells. Xenotransplantation mouse model further confirmed that co-treatment with lamivudine and sorafenib could reduce sorafenib-resistant HepG2.215 tumor cell growth.
Conclusion
cIAP2 is involved in HBV-induced sorafenib resistance in liver cancer and anti-HBV treatments reduce cIAP2 expression and partially restore sorafenib sensibility.
Activation of antiapoptotic genes has been indicated as one of the factors that contributes to hepatitis B virus (HBV) infection-induced liver cancer. The cellular inhibitor of apoptosis protein 2 (cIAP2), a member of the IAP family, is upregulated in various types of cancer and serves as a potential treatment target. However, to the best of our knowledge, the importance of cIAP2 in HBV-induced liver cancer has not been investigated. In the present study, cIAP2 expression in liver cells in response to HBV infection and the underlying mechanism involved was investigated. Western blot analysis of clinical liver samples showed that higher cIAP2 expression was detected in HBV-positive non-cancerous tissue compared with that in HBV-negative non-cancerous tissue, and the expression was further increased in HBV-positive liver cancer tissue. Reverse transcription-quantitative PCR and western blot experiments performed on two liver cell lines also confirmed that cIAP2 expression was increased upon HBV infection at both the mRNA and protein levels. Promoter analysis revealed that HBV could activate cIAP2 promoter in an infection dose-dependent manner, and this activation involved a NF-κB-binding site in the cIAP2 promoter. Further analysis demonstrated that HBV enhanced NF-κB phosphorylation and nuclear translocation via the PI3K/AKT signaling pathway, leading to the binding and activation of cIAP2 promoter. The present data demonstrates that HBV-infection induces cIAP2 expression in the liver by activation of the PI3K/AKT/NF-κB signaling pathway through promoting the binding of NF-κB to cIAP2 promoter, which may lead to carcinogenesis. The findings from the present study provide more information for understanding HBV-induced liver cancer and also offer a potential target for treatment or diagnosis of this disease.
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