ESM1/HIF‑1α pathway modulates chronic intermittent hypoxia‑induced non‑small‑cell lung cancer proliferation, stemness and epithelial‑mesenchymal transition.

Obstructive sleep apnea (OSA) is a sleep‑related disorder characterized by chronic intermittent hypoxia (CIH). Previous studies have found that intermittent hypoxia promotes drug resistance, cell proliferation, migration and invasion in non‑small cell lung cancer (NSCLC). Endothelial cell‑specific molecule‑1 (ESM1) is a molecule shown to be overexpressed in several types of tumors. The purpose of this study was to investigate the correlation between CIH and ESM1 and their potential roles in the progression of NSCLC. Tumorspheres, cell viability and colony formation assays were used to evaluate cell proliferation. The expression levels of cancer stem cell (CSC) markers CD44, CD133, OCT4 and SOX2 were measured with western blotting and/or RT‑qPCR. Transwell assays were applied to assess cell migration and invasion. Changes in the expression levels of epithelial‑mesenchymal transition (EMT)‑associated proteins were also detected by western blotting. The results indicated that CIH enhanced lung cancer stem cell (LCSC) NSCLC progression by promoting stemness, drug resistance, cell proliferation, migration and invasion via the ESM1/HIF‑1α pathway. Unexpectedly, inhibition of ESM1 reversed the CIH‑involved negative effects on LCSCs and in a mouse model. ESM1 therefore appears to be crucial mediator of CIH‑mediated lung cancer progression.