m6A modification of circCOQ10A potentiates N2 neutrophil polarization to accelerate gastric cancer progression and cisplatin resistance by regulating MAPK6/CXCL2 signaling

Abstract Background Circular RNAs (circRNAs) are well-recognized as critical diagnostic biomarkers and functional regulators in various malignancies, including gastric cancer (GC). N6-methyladenosine (m 6 A) RNA modification represents the most prevalent post-transcriptional modification and exerts pivotal regulatory functions in tumor progression. However, the functional implications and molecular mechanisms of m 6 A-modified circRNAs in GC malignant progression remain poorly elucidated. Herein, this study aimed to investigate the biological role and underlying mechanism of m 6 A modification on circCOQ10A in GC progression and cisplatin (DDP) resistance. Methods The m 6 A modification status of hsa_circ_0026967 (circCOQ10A) was verified through quantitative real-time PCR, methylated RNA immunoprecipitation, and Western blot assays. Gain- and loss-of-function experiments combined with in vivo tumorigenesis and metastasis models were performed to validate the oncogenic role of circCOQ10A in GC progression and DDP resistance. RNA immunoprecipitation and dual-luciferase reporter assays were conducted to confirm the direct binding interaction between circCOQ10A and miR-144-3p. Western blot analysis, flow cytometry, and cell co-culture systems were further utilized to clarify the regulatory effects of circCOQ10A on MAPK6/CXCL2 signaling and subsequent N2 neutrophil polarization. Fluorescence in situ hybridization was applied to detect the tissue localization of circCOQ10A and evaluate its clinical prognostic significance in GC patients. Results Our results demonstrated that circCOQ10A underwent robust m 6 A modification mediated by METTL14. METTL14 knockdown diminished the m 6 A modification level of circCOQ10A while elevating its endogenous expression. Functional experiments revealed that circCOQ10A knockdown suppressed GC cell proliferation, metastasis, and DDP resistance both in vitro and in vivo , whereas circCOQ10A overexpression yielded the opposite oncogenic effects. Further mechanistic validation indicated that circCOQ10A functioned as a competing endogenous RNA to sponge miR-144-3p, thereby upregulating MAPK6 expression and triggering the activation of the CXCL2/CXCR2 signaling axis. This activated signaling cascade ultimately facilitated N2-like neutrophil polarization and GC cell invasion. Clinically, circCOQ10A was significantly upregulated in GC tissues, and its high expression was closely correlated with unfavorable clinical prognosis in GC patients. Conclusions The present study reveals that METTL14-mediated m 6 A modification of circCOQ10A promotes N2 neutrophil polarization, thereby driving GC malignant progression and DDP resistance through the activation of the MAPK6/CXCL2 signaling pathway.