Objective: To investigate the cross-talk between nuclear factor kappaB (NF-kappaB) and P53 signal pathways in human epidermal keratinocytes (NHEKs) after ultraviolet B (UVB) irradiation.
Methods: Normal NHEKs harboring wild p53 gene and immortal human keratinocytes of the line HaCaT harboring mutant p53 gene were cultured at 37 degrees C in an atmosphere containing 5% CO(2) and then underwent irradiation of UVB of the dose of 60 mJ/cm(2). Part of the NHEKs and HaCaT cells were pretreated with BAY11-7082, NF-kappaB inhibitor inhibiting IkB-a phosphorylation, of the final concentration of 5 micromol/L. Western blotting was used to detect the protein expression of NF-kappaB, P53, and P21. The transcriptional activity of NF-kappaB was analyzed by electrophoretic mobility shift assay (EMSA).
Results: UVB irradiation increased the protein expression of NF-kappaB, P53, and P21 and triggered the transcriptional activity of NF-kappaB. BAY11-7082 significantly inhibited the NF-kappaB protein expression induced by UVB irradiation in the NHEKs and HaCaT cells. The P53 protein expression of the NHEKs undergoing pretreatment of BAY11-7082 and UVB irradiation was 0.08 +/- 0.07, significantly lower than that of the NHEKs undergoing only UVB irradiation (0.78 +/- 0.32, P < 0.01). The P21 protein expression of the NHEKs undergoing pretreatment of BAY11-7082 and UVB irradiation was 0.65 +/- 0.22, significantly lower than that of the NHEKs undergoing only UVB irradiation (1.58 +/- 0.77, P < 0.05). However, the P53 and the P21 protein expression of the HaCaT cells undergoing pretreatment of BAY11-7082 and UVB irradiation was not significantly different from that of the HaCaT cells undergoing only UVB irradiation.
Conclusion: There exists a UVB-induced cross-talk between NF-kappaB and P53 signal pathways in human epidermal keratinocytes. This cross-talk is correlated with P53 functional condition.