LncRNA FOXD2-AS1 as a competitive endogenous RNA against miR-150-5p reverses resistance to sorafenib in hepatocellular carcinoma

: The current study elucidated the role of a long non-coding RNA (lncRNA), FOXD2-AS1, in the pathogenesis of hepatocellular carcinoma (HCC) and the regulatory mechanism underlying FOXD2-AS1/miR-150-5p/transmembrane protein 9 (TMEM9) signalling in HCC. Microarray analysis was used for preliminary screening of candidate lncRNAs in HCC tissues. qRT-PCR and Western blot analyses were used to detect the expression of FOXD2-AS1. Cell proliferation assays, luciferase assay and RNA immunoprecipitation were performed to examine the mechanism by which FOXD2-AS1 mediates sorafenib resistance in HCC cells. FOXD2-AS1 and TMEM9 were significantly decreased and miR-150-5p was increased in SR-HepG2 and SR-HUH7 cells compared with control parental cells. Overexpression of FOXD2-AS1 increased TMEM9 expression and overcame the resistance of SR-HepG2 and SR-HUH7 cells. Conversely, knockdown of FOXD2-AS1 decreased TMEM9 expression and increased the sensitivity of HepG2 and Huh7 cells to sorafenib. Our data also demonstrated that FOXD2-AS1 functioned as a sponge for miR-150-5p to modulate TMEM9 expression. Taken together, our findings revealed that FOXD2-AS1 is an important regulator of TMEM9 and contributed to sorafenib resistance. Thus, FOXD2-AS1 may serve as a therapeutic target against sorafenib resistance in HCC.