Upregulation of lncRNA NIFK-AS1 in hepatocellular carcinoma by m6A methylation promotes disease progression and sorafenib resistance.

Long non-coding RNAs (LncRNAs) have recently emerged as vital regulators in the development and progression of hepatocellular carcinoma (HCC), providing new opportunities as novel therapeutic targets. Here we identified the lncRNA NIFK-AS1 as being highly expressed in HCC tissues and cells and showed this up-regulation resulted from METTL3-dependent m6A methylation. Functionally, knockdown of NIFK-AS1 inhibited the proliferation, colony formation, migration, and invasion of HCC cells. Moreover, these effects were elicited though AKT1 and we uncovered a ceRNA network involving an NIFK-AS1/miR-637/AKT1 axis with downstream effects on HCC progression involving regulation of MMP-7 and MMP-9 expression. From the clinical perspective, we showed that knockdown of NIFK-AS1 sensitized HCC cells to sorafenib through the up-regulation of the drug transporters OATP1B1 and OATP1B3. Clinical investigations showed HCC patients with low NIFK-AS1 expression benefited from sorafenib therapy and this phenomenon was reproduced in patient-derived tumor xenograft models (PDX) comparing HCC with low and high expression of NIFK-AS1. Taken together, these results suggest an essential role for NIFK-AS1 in HCC progression and promote NIFK-AS1 as a new therapeutic target and predictor of sorafenib benefit in HCC patients.