Effect of eukaryotic translation initiation factor 4γ2 on the malignant phenotype of gastric cancer cells regulated by N-acetylgalactosaminotransferase 1 mRNA

Objective To explore the impacts of eukaryotic translation initiation factor 4γ2 (EIF4G2) on gastric cancer progression via stabilizing N-acetylgalactosaminyltransferase 1 (GALNT1) mRNA.

Methods Bioinformatics database detected GALNT1 and EIF4G2 expression in gastric cancer cells and tissues, the association between GALNT1, EIF4G2 expressions and the prognosis of gastric cancer patients and the correlation between GALNT1 and EIF4G2 expression in gastric cancer tissues. Reverse-transcription quantitative polymerase chain reaction(RT-qPCR) examined levels of GALNT1 and EIF4G2 mRNA expression and western blot examined GALNT1 and EIF4G2 protein levels in human gastric mucosal epithelial GES-1 cell line and gastric cancer cells. AGS cell lines with GALNT1 interference or EIF4G2 overexpression plasmids were established. Cell proliferation was estimated by CCK-8 and colony formation assays. Cell apoptosis was evaluated by TUNEL assay. Cell migration and invasion were respectively measured through wound healing and transwell assays. Western blot was used to test the expression levels of apoptosis-and metastasis-associated proteins. RIP and RNA pull down assays was used to detect the binding relationship between GALNT1 mRNA and EIF4G2.

Results The expression levels of GALNT1 and EIF4G2 were significantly higher in gastric cancer tissues and cells than those in the normal tissues and human gastric mucosal epithelial cell line (P < 0.001), and associated with poor prognosis of gastric cancer patients. EIF4G2 expression was positively correlated with GALNT1 expression in gastric cancer. After GALNT1 was knocked down, cell viability was significantly reduced, the number of colony formation, migrated and invasive cells was significantly decreased and the number of apoptotic cells was significantly increased (P < 0.001). Bcl-2, MMP2 and MMP9 protein expressions were significantly decreased, while Bax, cleaved-caspase3, cleaved-caspase9 protein expressions were significantly increased (P < 0.001). EIF4G2 bonded to GALNT1 mRNA, and significantly enhanced GALNT1 mRNA expression, GALNT1 protein expression and GALNT1 mRNA stability (P < 0.001). Further more, co-transfection of sh-GALNT1-1 and oe-EIF4G2 significantly reversed the impacts of sh-GALNT1-1 on the proliferation, apoptosis, migration and invasion of AGS cells (P < 0.05, P < 0.01 or P < 0.001).

Conclusion EIF4G2 might accelerate the proliferation, migration, invasion and suppress the apoptosis of gastric cancer cells via stabilizing GALNT1 mRNA, which is expected to become a novel target for clinical diagnosis and treatment of gastric cancer.