Various UVB doses affect change of raf kinase inhibitor protein, nitric oxide and proliferation in keratinocytes

UVB is a potent modulator of cell growth and differentiation in the skin. The UVB irradiation has been used in treating hyperproliferative dermatoses. Otherwise, UVB radiation is also the major risk factor for developing skin cancer. Nitric oxide (NO) has been suggested to be a physiological modulator of cell proliferation. Raf-1 kinase inhibitory protein (RKIP) was involved in cell growth, transformation, and differentiation. The purpose of this study was to search for the possible cause of UVB-inhibited hyperplasia and UVB-resulted hyperproliferation. We evaluated various UVB dose whether affect the expression of RKIP, iNOS, NO and proliferation in keratinocyte. Normal human keratinocytes were treated with UVB dose of 40mJ/cm², 80mJ/cm², 120mJ/cm², 160mJ/cm² and 0mJ/cm² (control group) respectively. The results showed that RKIP, iNOS and NO of keratinocytes with doses of 40mJ/cm² and 80mJ/cm² UVB treatment significantly higher than control group (P<0.01). The proliferation of keratinocyte with doses of 40mJ/cm² and 80mJ/cm² UVB treatment was significantly lower than control group (P<0.01). However, RKIP, iNOS and NO of keratinocytes with doses of 120mJ/cm² and 160mJ/cm² UVB treatment significantly lower than control group (P<0.01). The proliferation of keratinocyte with doses of 120mJ/cm² and 160mJ/cm² UVB treatment was significantly higher than control group (P<0.01). In conclusion, these results showed that the different UVB dosages induced various alteration of RKIP, NO, iNOS and proliferation may provide important information on the therapeutic molecular mechanism of UVB-inhibited hyperplasia and UVB resulted hyperproliferation.