OTUD7B Stabilization by METTL14-Mediated m6A Methylation Drives HIF-1α Expression in Esophageal Squamous Cell Carcinoma.

Objectives: Epigenetic changes, particularly N6-methyladenosine (m6A) modifications, play a pivotal role in cancer development. This study explored the role of ovarian tumor deubiquitinase 7B (OTUD7B) in esophageal squamous cell carcinoma (ESCC) in the context of m6A methylation and the hypoxia-inducible factor-1α (HIF-1α) pathway.

Methods: The GSE179267 dataset was used to conduct differential gene expression analysis to identify key m6A-enriched genes. The Cancer Genome Atlas (TCGA), Cancer Cell Line Encyclopedia (CCLE), and Sequence-based RNA Adenosine Methylation Site Predictor (SRAMP) databases were used to evaluate the expression of OTUD7B in ESCC and its correlation with methyltransferase-like 14 (METTL14) and HIF-1α. The m6A content in total RNA extracted from ESCC cells was assessed using a dot blot assay. Gene-specific m6A-PCR was used to quantify m6A modifications in OTUD7B mRNA. The functional role of OTUD7B was explored using clonogenic and Transwell assays. The effect of OTUD7B on HIF-1α ubiquitination was detected using a co-immunoprecipitation assay.

Results: OTUD7B was identified as a pivotal m6A-driven oncogene correlated with METTL14 and HIF-1α. METTL14 enhanced the mRNA stability and expression of OTUD7B through m6A methylation. OTUD7B overexpression counteracted the inhibitory effects of METTL14 knockdown on cell proliferation and invasion and stabilized HIF-1α by promoting deubiquitination.

Conclusion: METTL14 plays a crucial role in the stabilization of OTUD7B through m6A methylation, thereby inhibiting the ubiquitin-proteasomal degradation of HIF-1α in ESCC. These findings highlight the potential of targeting the METTL14-OTUD7B axis as a therapeutic strategy for ESCC.