Downregulation of fibroblast growth factor 5 inhibits cell growth and invasion of human nonsmall-cell lung cancer cells.

The morbidity and mortality rates of nonsmall-cell lung cancer (NSCLC) have increased in recent years. We aimed to explore the biological role of fibroblast growth factor 5 (FGF5) in NSCLC. We first established that the expression of FGF5 was increased in NSCLC tissues compared with the normal adjacent tissues. The expression of FGF5 was also increased in NSCLC cell lines. The effect of FGF5 silencing on cell proliferation, cell cycle, apoptosis, migration, and invasion of H661 and CALU1 cells was then examined. Downregulation of FGF5 significantly inhibited cell proliferation and induced G1 phase cell cycle arrest compared with the negative control small interfering (siNC) groups. Cell apoptosis was promoted by siFGF5 treatment. Cell migration and invasion of H661 and CALU1 cells with siFGF5 transfection were markedly diminished compared with the siNC groups. In addition, migration and invasion-associated proteins (E-cadherin, matrix metalloproteinase-2 [MMP-2], and MMP-9) and epithelial mesenchymal transition markers (N-cadherin, vimentin, snail, and slug) were also regulated by FGF5 siRNA treatment. Gene set enrichment analysis on The Cancer Genome Atlas dataset showed that the Kyoto Encyclopedia of Genes and Genomes (KEGG) cell cycle and vascular endothelial growth factor (VEGF) pathways were correlated with FGF5 expression, which was further confirmed in NSCLC cells by Western blot analysis. Our results indicated that FGF5 silencing suppressed cell growth and invasion via regulation of the cell cycle and VEGF pathways. Therefore, FGF5 may serve as a promising therapeutic strategy for NSCLC.