Elevation of EIF4G1 promotes non-small cell lung cancer progression by activating mTOR signalling

Abstract

Eukaryotic translation initiation factor 4 gamma 1 (EIF4G1), as the key component of the transcription initiation factor complex EIF4F, is significantly upregulated in multiple solid tumours, including lung cancer. However, the function and mechanism of EIF4G1 in the regulation of non-small-cell lung cancer (NSCLC) remain unclear. Here, using the clinical samples and the comprehensive survival analysis platforms Kaplan-Meier plotter, we observed aberrant upregulation of EIF4G1 in NSCLC tissues; furthermore, high expression of EIF4G1 showed association with low differentiation of lung cancer cells and poor overall survival in NSCLC patients. Non-small-cell lung cancer cell line A549 and H1703 stably infected with EIF4G1 shRNA were used to determine the function of EIF4G1 in regulating cell proliferation and tumorigenesis in vitro and in vivo. The results demonstrated that EIF4G1 promoted the G1/S transition of the cell cycle and tumour cell proliferation in non-small cell lung cancer. Mechanistically, EIF4G1 was found to regulate the expression and phosphorylation of mTOR (Ser2448), which mediates the tumorigenesis-promoting function of EIF4G1. The inhibition of mTOR attenuated the EIF4G1-induced development and progression of tumours. These findings demonstrated that EIF4G1 is a new potential molecular target for the clinical treatment of non-small cell lung cancer.