ALYREF-Mediated Regulation of TBL1XR1 and KMT2E Synergistically Upregulates APOC1, Contributing to Oxaliplatin Resistance in Esophageal Cancer.

Purpose: Esophageal cancer (EC) is a rapidly progressing malignancy characterized by a low survival rate and limited treatment success, largely due to late-stage detection, frequent recurrence, and a high propensity for metastasis, despite ongoing advances in therapeutic strategies. While oxaliplatin (L-OHP) is a potent chemotherapeutic agent that induces apoptosis in EC cells, its effectiveness is significantly hindered by the development of resistance.

Materials and methods: The assessment of gene and protein expression was conducted through a combination of quantitative real-time polymerase chain reaction, Western blot, and immunohistochemical staining. Cell viability was assessed using the cell counting kit-8 assay. The interactions among ALYREF, TBL1XR1, KMT2E, and APOC1 were investigated through RNA immunoprecipitation, chromatin immunoprecipitation (ChIP), ChIP-reChIP, RNA pulldown, and dual-luciferase assays. An in vivo mouse model of EC was established.

Results: Expression levels of both APOC1 and ALYREF were elevated in L-OHP-resistant EC tissues and cell lines, and their silencing enhanced sensitivity to L-OHP. TBL1XR1 and KMT2E synergistically upregulated APOC1 expression. Moreover, ALYREF recognized the 5-methylcytosine (m5C) sites on TBL1XR1 and KMT2E mRNAs, stabilizing these transcripts and promoting APOC1 expression. The regulatory role of these interactions was further validated in vivo.

Conclusion: This study demonstrated that ALYREF interacted with the m5C sites on TBL1XR1 and KMT2E mRNAs, enhancing their stability and leading to increased transcription of APOC1, which in turn contributed to L-OHP resistance in EC. These findings suggest that targeting APOC1 could be a promising strategy for overcoming L-OHP resistance in EC.