Hypoxia-inducible factor-1α promotes proliferation of airway smooth muscle cells through miRNA-103-mediated signaling pathway under hypoxia.

The hypoxia-inducible factor-1α (HIF-1α) activated during asthma development plays a causative role in the abnormal proliferation of airway smooth muscle (ASM) cells and consequential airway remodeling. Although the underlying mechanisms of HIF-1α activity have not been fully revealed, HIF-1α-regulated miRNA signaling is considered important for disrupted differentiation and proliferation of local cells in various tissues under inflammation. We aimed to identify the key miRNA signaling involved in HIF-1α regulation of the proliferation of ASM cells. This study was based on primary ASM cells isolated from adult male rats. Three percent O2 and 21% O2 were set as hypoxic and normoxic condition for ASM cell treatment, respectively. Knockdown of HIF-1α was performed through transfection of pSUPER-shHIF-1α plasmid. Overexpression and knockdown of miRNA-103 were performed through transfection of miRNA-103 mimic or inhibitor, respectively. Levels of HIF-1α, PTEN, and PCNA were determined with Western blot and RT-qPCR. Hypoxia increased HIF-1α and miRNA-103 expression and proliferation in ASM cells. Knockdown of HIF-1α suppressed hypoxia-induced upregulation of proliferation and miRNA-103 expression in ASM cells. Knockdown of miRNA-103 displayed similar effects as knockdown of HIF-1α in ASM cells under hypoxia, while overexpression of miRNA-103 played the opposite role. Additionally, increased or decreased expression of PTEN was also detected when HIF-1α/miRNA-103 was knocked down under hypoxia or miRNA-103 was overexpressed under normoxia, respectively. Our results suggest that HIF-1α promotes the proliferation of ASM cells via upregulating miRNA-103 expression under hypoxia, and PTEN is involved in the miRNA-103-mediated signaling pathway.