Gli promotes tumor progression through regulating epithelial-mesenchymal transition in non-small-cell lung cancer

Lung cancer is the leading causes of cancer-related deaths globally. The most frequent histologic type of lung cancer is non-small-cell lung cancer (NSCLC). NSCLC often undergo epithelial-mesenchymal transition (EMT). The components that control this process are thus promising therapeutic targets.

Gli/EMT protein expression levels were examined by western blot in paired NSCLC patient tissues and NSCLC cell lines. Functional analyses were performed to investigate SHH/Gli signaling and EMT in NSCLC cell lines. MTS cell viability, luciferase reporter, and western blot assays were performed to analyze pathway activity, while wound healing and transwell assays were executed to measure cell migration and invasion.

Higher Gli1 expressions were detected in tumor samples than in paired normal tissues. Differential expression of EMT biomarkers and activation of p-AKT were observed in tumor tissues. N-Shh stimulation of cells significantly increased reporter activity in NSCLC cell lines, while Gli-i treatment of transfected cells showed less relative reporter activity. When subjected to both Gli-i and N-Shh treatment, NSCLC cell lines continued to demonstrate decreased Gli transcriptional activity. Gli inhibition is associated with decreased expression level of p-AKT, N-cadherin and Vimentin. Knockdown of both Gli1 and Gli2 showed decreased EMT, migrative and invasive ability. Cells stimulated by N-Shh demonstrated greater mobility. In addition, AKT-i treated cells also demonstrated inhibited EMT activity.

This study provides evidence for aberrant upregulation of the Gli signaling pathway and a strong association between expression of Gli versus AKT and EMT markers in NSCLC.