MDM2 And P53 Expression In Aqired Melanocytic Nevi And Epidermis

Objectives: To research the biology characteristics of AMN and the effect of the chronical sun irradiation on AMN and to analyse the roles of the types of AMN as one of phenotypes and the chronic sun irradiation as one of the environment factors in the multisteps of AMN malignant transformation by observing the MDM2 and p53 expression in aquired melanocytic nevi(AMN) nest and epidermis.Methods: Tissue sections were immunohistochemically stained . When cases having reactive cells were regarded as positive and the positive rate were taken as positive index. We have analysed the MDM2 and p53 positive index between the nevi clusters at the epidermal-dermal junction and ones in intraderm, and the type and the positive index of the epidermal p53 clones in epidermis specimens between the chronically sun-exposed skin and the shielded skin.Results:The positive cases for anti-MDM2 antibodies were not observed in the 30 specimens from the patients with AMN. Immunohistochemical analysis revealed that in AMN 6 of 30 (20%) were positive,i. e. , 2 in junctional nevi,1 in compound nevi and 3 in intradermal nevi. There was no significant differences between the p53 positive rate and index of the nevi clusters in junctional site and the ones of the nevi clusters in dermis (P >0. 05) . Although there was no significant differences for the p53 positive rate between the nevi in the chronically sun-exposed skin and the ones in the shielded skin (P >0. 05) , the former(3/8) is higher than the latter(3/22) .9 cases with epidermal p53 clones,which all were A types, were observed. The incidence of the epidermal p53 clones in the chronically sun-exposed skin was higher significantly than theones in the shielded skin (p <0.05) ,but no significant differences of the positive index(12.85%±1.18%) of the epidermal p53 clones in the epidermis over the nevi clusters to the one(11.29%±3.38%) in the epidermis beyond nevi clusters horizontally(t=l. 57, P =0.12).Conclusion:The biology characteristics of the three types of AMN are benign, and there may be no differences among the three types of AMN malignant transformation , and chronic sun irradiation can induce the development of the epidermal p53 clones and may induce p53 mutation in AMN clusters.It is very important to avoid chronic sun irradiation to prevent the p53 and MDM2 protein overexpression for preventing AMN malignant transformation.