Hepatocellular carcinoma (HCC) is a common cancer with poor prognosis. Hepatitis B virus (HBV) is one of the leading causes of HCC, but the precise mechanisms by which this infection promotes cancer development are not fully understood. Recently, miR-340-5p, a microRNA (miRNA) that has been identified as a cancer suppressor gene, was found to inhibit the migration and invasion of liver cancer cells. However, the effect of miR-340-5p on cell proliferation and apoptosis in HBV-associated HCC remains unknown. In our study, we show that miR-340-5p plays an important role during HBV infection and hepatocellular carcinoma development. Specifically, this miRNA directly binds to the mRNA encoding activating transcription factor 7 (ATF7), a protein that both promotes cell proliferation and suppresses apoptosis through its interaction with heat shock protein A member 1B (HSPA1B). We further found that miR-340-5p is downregulated by HBV, which enhances ATF7 expression, leading to enhanced cell proliferation and inhibition of apoptosis. Notably, ATF7 is upregulated in HCC tissue, suggesting that HBV may target miR-340-5p in vivo to promote ATF7/HSPA1B-mediated proliferation and apoptosis and regulate liver cancer progression. This work helps to elucidate the complex interactions between HBV and host miRNAs and further suggests that miR-340-5p may represent a promising candidate for the development of improved therapeutic strategies for HCC.
Keywords: ATF7; HBV-related HCC; apoptosis; miR-340-5p; proliferation.
© 2019 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.