N6-methyladenosine modification of hypoxia-inducible factor-1α regulates Helicobacter pylori-associated gastric cancer via the PI3K/AKT pathway.

Abstract

Helicobacter pylori (H. pylori) colonizes the human gastric mucosa and is implicated in the development of gastric cancer (GC). The tumor microenvironment is characterized by hypoxia, where hypoxia-inducible factor-1α (HIF-1α) plays a key role as a transcription factor, but the mechanisms underlying H. pylori-induced HIF-1α expression and carcinogenesis remain unclear. To explore the underlying mechanism of H. pylori-induced HIF-1α expression in promoting the malignant biological behavior of gastric epithelial cells (GES-1). The study was conducted with human GES-1 cells in vitro. Relative protein levels of methyltransferase-like protein 14 (METTL14), HIF-1α, main proteins of the PI3K/AKT pathway, epithelial-mesenchymal transition (EMT) biomarkers, and invasion indicators were detected by Western blot. Relative mRNA levels of METTL14 and HIF-1α were detected by quantitative reverse transcription-polymerase chain reaction. mRNA stability was evaluated using actinomycin D, and the interaction between METTL14 and HIF-1α was confirmed by immunofluorescence staining. Cell proliferation and migration were evaluated by cell counting kit-8 assay and wound healing assay, respectively. H. pylori promoted HIF-1α expression and activated the PI3K/AKT pathway. Notably, METTL14 was downregulated in H. pylori-infected gastric mucosal epithelial cells and positively regulated HIF-1α expression. Functional experiments showed that the overexpression of HIF-1α or knockdown of METTL14 enhanced the activity of the PI3K/AKT pathway, thereby driving a series of malignant transformation, such as EMT and cell proliferation, migration, and invasion. By contrast, the knockdown of HIF-1α or overexpression of METTL14 had an opposite effect. H. pylori-induced underexpression of METTL14 promotes the translation of HIF-1α and accelerates tumor progression by activating the PI3K/AKT pathway. These results provide novel insights into the carcinogenesis of GC.