DNMT1-Dependent DNA Methylation of lncRNA FTX Inhibits the Ferroptosis of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one of the most malignant solid tumors worldwide. Long non-coding RNAs (lncRNAs) are the key factor in the pathogenesis of HCC. This study aimed to investigate the roles of lncRNA FTX transcript, XIST regulator (FTX) in HCC. mRNA levels were detected using RT-qPCR. Protein expression was determined using Western blot. cellular functions were determined using Cell Counting Kit (CCK)-8 and propidium iodide (PI) staining assays. RNA fluorescent in situ hybridization (FISH) assay was conducted to analyze the location of lncRNA FTX and DNMT1. RNA pulldown, RNA immunoprecipitation (RIP), and chromatin-immunoprecipitation (ChIP) assays were used to ascertain the involved mechanisms. We found that FTX was downregulated in HCC patients, which was associated with poor prognosis. Moreover, DNA methyltransferase 1 (DNMT1)-mediated methylation of FTX promoter inhibited its expression. Interestingly, overexpression of FTX promoted the ferroptosis of HCC cells. FTX sponged miR-374b-3p to upregulate transferrin receptor (TFRC) expression. However, downregulation of miR-374b-3p or overexpression of TFRC alleviated the effects of FTX knockdown and promoted the survival of HCC cells. In conclusion, DNMT1-dependent DNA methylation of FTX promotes the development of HCC through regulating miR-374b-3p/TFRC axis. Therefore, DNMT1/FTX/miR-374b-3p/TFRC axis may be a potential target for HCC.