HBx/ERα complex-mediated LINC01352 downregulation promotes HBV-related hepatocellular carcinoma via the miR-135b-APC axis.

Hepatitis B virus (HBV) infection plays an important role in hepatocarcinogenesis, especially in hepatocellular carcinoma (HCC). Long non-coding RNAs (lncRNAs) have emerged as crucial biomarkers and regulators in many cancers. Novel lncRNAs involved in the initiation and progression of HBV-related hepatocellular carcinoma (HCC) need to be investigated. Here, we report that the long non-coding RNA LINC01352 is markedly downregulated by HBV/HBx (HBV X protein) in HCC cells and clinical samples. The LINC01352 expression level in HCC is an independent prognostic factor for survival. We found that HBx suppresses LINC01352 promoter activity by forming a complex with the estrogen receptor (ER alpha). Furthermore, using a combination of in vitro and in vivo studies, we confirmed that HBx promotes HCC cell growth and metastasis by inhibiting LINC01352 expression. Further investigation revealed that the downregulation of LINC01352, which acts as an endogenous sponge, increases the expression of miR-135b, leading to the reduced production of adenomatous polyposis coli (APC), consequently activating Wnt/beta-catenin signalling to facilitate tumour progression. These findings strongly suggest that the LINC01352-miR-135b-APC axis regulated by the HBx/ER alpha complex acts as an important pathogenic factor for tumour progression, which may help provide a theoretical basis for the identification of new therapeutic targets for HBV-related HCC.