Capsaicin inhibits the nuclear localization of HIF-1α by down regulating Cox-2 in a p53-dependent manner.

<p>(A) Immunoblot representing nuclear and cytosolic levels of HIF-1α in capsaicin-treated/p53-shRNA-transfected Hy-A549 cells. (B) HIF-1α expression was monitored in capsaicin-treated Hy-A549 cells by confocal microscopy (magnification 60x). (C) Time-dependent expression of Cox-2-mRNA and -protein in capsaicin-treated Hy-A549 cells was determined by Western blot and RT-PCR. (D) Control siRNA-/Cox-2-siRNA-transfected Hy-A549 cells were treated with capsaicin (37.5 µM; 24 h) and nuclear translocation of HIF-1α was assessed by Western blot analysis (<i>left panel</i>). Transfection efficiency was determined by analyzing the expression of Cox-2 (<i>right panel</i>). (E) Control vector-/Cox-2 cDNA transfected Hy-A549 cells were treated with capsaicin (37.5 µM; 24 h) and analyzed for nuclear and cytosolic expression of HIF-1α (<i>left panel</i>). Transfection efficiency of Cox-2 was also verified (<i>right panel</i>). (F) Control-shRNA-/p53-shRNA-transfected Hy-A549 cells were treated with capsaicin (37.5 µM; 24 h) and expression profiles of Cox-2 both at protein and mRNA level were examined. (G) Time-dependent expression profiles of SMAR1-protein and mRNA in capsaicin-treated Hy-A549 cells were determined by Western blot and RT-PCR (<i>left panels</i>). Control-/p53-shRNA transfected Hy-A549 cells were treated with capsaicin and expression levels of SMAR1 were checked (<i>right panel</i>). (H) Control-/SMAR1-shRNA transfected Hy-A549 cells were treated with capsaicin and immune-blotted with p-Ser¹⁵-p53. α-Actin/H1-Histone/GAPDH were used as internal loading control. Values are mean ± SEM of three independent experiments in each case or representative of typical experiment.