A novel lncRNA BF368575 promotes cell proliferation in hepatocellular carcinoma via PI3K/AKT/mTOR signaling pathway

Abstract

Abstract Purpose LncRNA-BF368575 is a novel long non-coding RNA, its biological function in hepatocellular carcinoma (HCC) remains unknown. Methods The expression levels of lncRNA-BF368575 in HCC tissues and cell lines were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In situ hybridization (ISH) was performed to determine the expression of lncRNA-BF368575 in a tissue chip containing 89 paired HCC and para-cancerous tissues. Fractionation of nuclear and cytoplasmic RNA was performed to determine the subcellular localization of lncRNA-BF368575. Cell viability and colony-forming ability were determined by cell counting kit-8 (CCK-8) assay and colony formation assay. Tumor growth in vivo was detected using the xenograft model. The molecular mechanisms of lncRNA-BF368575 were investigated using Western blotting and RNA-Binding Protein Immunoprecipitation (RIP). Results The results showed that lncRNA-BF368575 was increased in most HCC tissues and cell lines. Moreover, the lower lncRNA-BF368575 expression level is a favorable prognostic factor in disease-free survival (DFS). LncRNA-BF368575 is mostly localized in the cytoplasm. In vitro and in vivo experiments showed that downregulation of lncRNA-BF368575 suppressed cell proliferation and colony-forming activity, yet overexpression of lncRNA-BF368575 leads to an opposite result. Furthermore, lncRNA-BF368575 activates the PI3K/AKT/mTOR signaling pathway by increasing the expression of p-PI3K(Tyr607), p-AKT(Thr308), p-mTOR(Ser2448), p-4E-BP1(Thr37/46), p-S6(Ser235/236). LY294002 could reverse the biological functions of lncRNA-BF368575. RIP shows that LncRNA-BF368575 could bind to p-mTOR(Ser2448), p-AKT(Thr308), and p-4E-BP1(Thr37/46). Conclusion Our study demonstrates that lncRNA-BF368575 enhances HCC proliferation and growth both in vitro and vivo via activating the PI3K/AKT/mTOR signaling pathway, which implicates that our findings may provide a potential target for HCC treatments.