The m6A-induced lncRNA CASC8 promotes proliferation and chemoresistance via upregulation of hnRNPL in esophageal squamous cell carcinoma.

Abstract

Long noncoding RNAs (lncRNAs) are dysregulated in many cancers. Here, we identified the molecular mechanisms of lncRNA Cancer Susceptibility Candidate 8 (CASC8) in promoting the malignancy of esophageal squamous cell carcinoma (ESCC). CASC8 was highly overexpressed in ESCC tissues and upregulation of CASC8 predicted poor prognosis in ESCC patients. Moreover, CASC8 decreased the cisplatin sensitivity of ESCC cells and promoted ESCC tumor growth in vivo. Mechanistically, CASC8 interacted with heterogeneous nuclear ribonucleoprotein L (hnRNPL) and inhibited its polyubiquitination and proteasomal degradation, thus stabilizing hnRNPL protein levels and activating the Bcl2/caspase3 pathway. Additionally, AlkB Homolog 5, RNA demethylase (ALKBH5)-mediated m6A demethylation stabilized the CASC8 transcript, resulting in CASC8 upregulation. Taken together, these findings identified an oncogenic function of CASC8 in the progression of ESCC, which suggest that CASC8 might become a potential prognostic biomarker in ESCC.