Figure 3.

IL-6/STAT3 pathway increased HIF-1α expression directly via p-STAT3 binding with HIF-1α promoter. A. Bio-informatic analysis revealed that there were 27 potential p-STAT3 DNA binding sites found in the promoter of HIF-1α. B. Based on the location of these 27 potential binding sites, we divided the HIF-1α promoter into 3 regions which could be bound by p-STAT3 protein including Fraction 1, Fraction 2 and Fraction 3. ChIP assay confirmed that p-STAT3 protein was bound with all three fractions respectively. C. Luciferase reporter assessment displayed that IL-6 treatment enhanced the occupancy of p-STAT3 protein on all three fractions of HIF-1α promoter in Huh7 cells. And the p-STAT3 inhibitor Stattic repressed the bindings between p-STAT3 protein and these 3 fragments in MHCC97h cells.