Hypoxia-responsive lncRNA AC115619 encodes a micropeptide that suppresses m6A modifications and hepatocellular carcinoma progression.

Long non-coding RNAs (lncRNAs) regulate a number of aspects of cancer biology. Recent research has shown that lncRNAs can encode micropeptides that mediate their functions in tumors. Here, we revealed that the liver-specific putative lncRNA, AC115619, is expressed at low levels in hepatocellular carcinoma (HCC) and encodes a micropeptide, designated as AC115619-22aa. AC115619 played a crucial role in the regulation of tumor progression and was a prognostic indicator in HCC. The encoded micropeptide AC115619-22aa inhibited the progression of HCC by binding to WTAP and impeding the assembly of the N6-methyladenosine (m6A) methyltransferase complex, which regulates the expression of tumor-associated genes, such as SOCS2 and ATG14. AC115619 was co-transcribed with the adjacent upstream coding gene APOB, and hypoxia induced transcriptional repression of both APOB and AC115619 by controlling HIF1A/HDAC3 and HNF4A signaling. In animal and patient-derived models, AC115619-22aa reduced global m6A levels and suppressed tumor growth. In conclusion, this study establishes AC115619 and its encoded micropeptide as potential prognostic markers and therapeutic targets for patients with HCC.