The cancer-testis lncRNA lnc-CTHCC promotes hepatocellular carcinogenesis by binding hnRNP K and activating YAP1 transcription

Cancer-testis (CT) genes participate in the initiation and progression of cancer, but the role of CT-associated long non-coding RNAs (CT-lncRNAs) in hepatocellular carcinoma (HCC) is still elusive. Here, we discovered a conserved CT-lncRNA, named lnc-CTHCC, which was highly expressed in the testes and HCC. A lnc-CTHCC-knockout (KO) mouse model further confirmed that the global loss of lnc-CTHCC inhibited the occurrence and development of HCC. In vitro and in vivo assays also showed that lnc-CTHCC promoted HCC growth and metastasis. Mechanistically, lnc-CTHCC bound to heterogeneous nuclear ribonucleoprotein K (hnRNP K), which was recruited to the YAP1 promoter for its activation. Additionally, the N6-methyladenosine (m6A) modification was mediated by N6-adenosine-methyltransferase 70-kDa subunit (METTL3) and recognized by insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1)/IGF2BP3, which maintained lnc-CTHCC stability and increased its expression in HCC. Together, our results show that lnc-CTHCC directly binds to hnRNP K and promotes hepatocellular carcinogenesis and progression by activating YAP1 transcription, suggesting that lnc-CTHCC is a potential biomarker and therapeutic target of HCC.