Effect of ultraviolet radiation on the exp ression of p53, matrix metalloproteinase-2 and-9 in actinic keratosis lesions and normal human skin / 中华皮肤科杂志

ABSTRACT

Objective To estimate the effect of different doses of ultraviolet (UV) radiation on the proliferation of and apoptosis in kertatinocytes,as well as on the expression of p53,matrix metalloproteinase-2 (MMP2) and-9 (MMP9) in actinic keratosis (AK) lesions and normal human skin.Methods Tissue specimens were obtained from the lesions of 20 patients with AK and sun-exposed normal skin of 20 healthy human subjects,and subjected to an air-exposed culture.Each of the specimens was divided into 4 areas to remain untreated (control area) or be irradiated with UV of 5,10 and 20 J/cm2 (irradiated areas) for 4 consecutive days.After another 24-hour culture,the tissue cultures were collected followed by the evaluation of apoptosis in and proliferation of keratinocytes by using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Ki-67 staining,and determination of mRNA and protein expressions of p53,MMP2 and MMP9 by using real time PCR and immunohistochemistry respectively.Results A statistical increase was observed in the percentage of apoptotic cells in the normal skin irradiated with UV of 10 and 20 J/cm2 (46.8％ ± 2.1％ and 56.7％± 2.4％,both P ＜ 0.05) and in the AK lesions irradiated with UV of 20 J/cm2 (43.5％ ± 1.5％,P ＜ 0.05)compared with the corresponding unirradiated tissues.The normal skin showed a higher percentage of apoptotic cells than the lesional skin after irradiation with UV of 10 and 20 J/cm2 (both P ＜ 0.05).The percentage of Ki67-positive cells was significantly decreased in the normal skin after irradiation with UV of 20 J/cm2 (3.34％ ±0.76％,P ＜ 0.05),but experienced no statistical changes in the lesional skin after different doses of UV irradiation (all P ＞ 0.05).There was a statistical elevation in the expression of p53 mRNA (5 J/cm21.106 ± 0.025,10 J/cm2 1.259 ± 0.045,20 J/cm21.425 ± 0.053,all P ＜ 0.05) and protein(10 J/cm20.1169 ± 0.0032,20 J/cm20.1454 ± 0.0047,both P＜ 0.05) in the normal skin,but a statistical reduction in the expression of p53 mRNA(10 J/cm2.0.611 ± 0.050,20 J/cm20.578 ± 0.070,both P ＜ 0.05) and protein (20 J/cm20.0404 ± 0.0027,P＜ 0.05) in the lesional skin after irradiation compared with the corresponding unirradiated skin tissues.Further more,a statistical increment was observed in MMP2 mRNA and protein expression in normal skin irradiated with UV of 10 J/cm2 (1.086 ± 0.013,0.0843 ± 0.0024,respectively,both P ＜ 0.05) and 20 J/cm2 (1.417 ± 0.036,0.1236 ±0.0042,respectively,both P ＜ 0.05) and in lesional skin irradiated with UV of 20 J/cm2 (1.296 ± 0.028,0.0744± 0.0032,respectively,both P ＜ 0.05),as well as in MMP9 mRNA and protein expression in normal skin irradiated with UV of 20 J/cm2 (1.395 ± 0.026,0.3065 ± 0.0162,respectively,both P ＜ 0.05) and in lesional skin irradiated with UV of 10 J/cm2 (1.298 ± 0.035,0.0992 ± 0.0053,respectively,both P ＜ 0.05) and 20 J/cm2(1.286 ± 0.032,0.1010 ± 0.0063,respectively,both P ＜ 0.05) compared with the corresponding unirradiated tissues.Conclusion Ultraviolet may accelerate the progression of AK by down-regulating p53 expression but up-regulating MMP2 and MMP9 expression.