Figure 6.

Suppression by Wnt/β-catenin of XBP1s promotion of HIF1α transcriptional activity. A and B, HIF1α-activated luciferase reporter assays. A, HEK293 cells were transiently co-transfected with 5xHRE-luciferase reporter plasmid together with vector or XBP1s-expressing plasmid for 24 h. Cells were cultured in LCM or WCM and exposed to normoxia (N) or 1% O₂ hypoxia (H) for 12 h. Cell lysates were used for luciferase activity measurement. B, HEK293 cells were co-transfected with 5xHRE-luciferase reporter together with the indicated plasmids for 24 h, followed by measurement of luciferase activity. C, RKO cells were transfected with vector or XBP1s plasmid for 24 h and cultured in LCM or WCM in the absence or presence of 100 μm CoCl₂ for 12 h. Quantitative RT-PCR analysis of the mRNA abundance for the indicated HIF1α target genes is shown. All data are shown as the mean ± S.D. from three independent experiments after normalization to the values of vector control or LCM-cultured cells. *, p < 0.05; **, p < 0.01; and ***, p < 0.001 by Student's t test.