Modification of STIM2 by m⁶A RNA methylation inhibits metastasis of cholangiocarcinoma

N6-methyladenosine (m⁶A) is the most frequent internal methylation of eukaryotic RNA (ribonucleic acid) transcripts and plays an important function in RNA processing. The current research aimed to investigate the role of m⁶A-STIM2 axis in cholangiocarcinoma (CCA) progression.

The expression of STIM2 (Stromal Interaction Molecule 2) in CCA was measured using quantitative polymerase chain reaction (PCR) and immunohistochemistry (IHC). STIM2 was examined in vivo for its effects on the malignant phenotypes of CCA cells. The m⁶A modification of STIM2 was assessed through MeRIP (methylated RNA Immunoprecipitation)-PCR.

Based on the GEPIA (Gene Expression Profiling Interactive Analysis) 2 database findings, a low STIM2 mRNA (messenger RNA) level was related to a poor prognosis in individuals with CCA. Quantitative PCR and IHC assays indicated decreased protein satin in CCA tissues and were associated with extrahepatic metastasis. Vianude mice tail vein injection model indicated that increased STIM2 levels suppressed CCA cell metastasis in vivo, while KRT8 (keratin 8) was detected as the direct downstream target of STIM2-mediated CCA cell metastasis in vivo. Meanwhile, based on SRAMP database and MeRIP assays indicated that m⁶A alteration resulted in abnormal STIM2 expression in CCA via METTL14 and YTHDC2.

Our findings revealed the epi-transcriptomic dysregulation in CCA and metastasis by proposing a complicated STIM2-KRT8 regulatory paradigm based on m⁶A alteration.