Figure 8. CXCR3 is a HIF-1 target gene.

(A) Candidate HREs were identified in the 5′-flanking region (HRE-1) and 3′-untranslated region (HRE-2) of the human CXCR3 gene. HREs containing the WT (5′-ACGTG-3′) or mutant (Mut; 5′-AAAAG-3′) HIF-1 binding site sequence were inserted into the Fluc vector pGL2 promoter. (B–E) MDA-231 BCCs were incubated at 20% or 1% O₂ for 24 hours, and ChIP assays were performed using IgG, HIF-1α, or HIF-1β antibodies. Specific primers flanking HRE-1 and HRE-2 were used for qPCR, and values were normalized to IgG at 20% O₂ (mean ± SEM; n = 3). *P < 0.05 vs. all other conditions, Student’s t test on log-converted values. (F and G) pGL2 promoter containing WT or mutant HRE was cotransfected with pSV-Renilla into MDA-231 BCCs, which were incubated at 20% or 1% O₂ for 24 hours. The Fluc/Rluc ratio was normalized to WT at 20% O₂ (mean ± SEM; n = 3). *P < 0.05 vs. 20% WT; ^#P < 0.05 vs. 1% WT, Student’s t test.