Fig. 9.

SOS1-IT1 is upregulated under hypoxia and directly transactivated by HIF-1α. a The Ishikawa cells were treated with hypoxia or its chemical inducer CoCl₂ for 24 h, and the expression level of SOS1-IT1 was detected by real-time PCR. b–c HIF-1α was knocked down by two different HIF-1α small interfering RNA (siRNA), and the expression level was analyzed by western blot (b). The expression level of SOS1-IT1 was analyzed after knocking down HIF-1α, both in normoxia and hypoxia condition (c). d Schematic illustration of the putative HIF-1α binding site in SOS1-IT1 gene promoter. e The dual-luciferase reporter assays were performed in Ishikawa cells transfected with different reporter constructs, both in normoxia and hypoxia condition. f The ChIP assays were performed using control IgG or anti-HIF-1α antibody in Ishikawa cells. The binding of HIF-1α on SOS1-IT1 promoter was analyzed by real-time PCR. G The dual-luciferase reporter assays were performed in Ishikawa cells when knocking down HIF-1α with two different siRNAs. h The cell growth was performed by WST-1 assays after SOS1-IT1 knocked down in normoxia or hypoxia condition. i The Ishikawa cells were overexpressed with flag tagged HIF-1α, and the expression of HIF-1α protein was verified by western blot. The flag tagged HIF-1α followed was detected by immunoblotting with an anti-flag antibody, and the actin protein act as internal reference. j The cell growth was performed by WST-1 assays after HIF-1α overexpression with SOS1-IT1 knocked down. ** P < 0.01, ***P < 0.001