Overexpression of the p53 gene product has been observed in a high percentage of
malignant melanomas. To evaluate the role of this
protein in the development of
melanoma, we examined p53 expression in benign, premalignant, and malignant melanocytic lesions. Using the
antibodies DO-7 and 1801, which recognize both wild-type and most mutant forms of the p53
protein, we analyzed by immunohistochemical staining 26 benign
nevi, 34
dysplastic nevi from patients at low risk for the development of
melanoma, 22
dysplastic nevi from patients at high risk for the development of
melanoma, 61 primary
melanomas (including 15 that arose from
dysplastic nevi), and 10 metastatic
melanomas. Expression of the p53
protein was not observed in any of the benign or
dysplastic nevi. Of the primary
melanomas only 3 (5%) demonstrated nuclear staining, whereas 70% of the metastatic
melanomas showed a positive reaction for p53. These data suggest that overexpression of the p53 gene product is a late event in the progression of
melanoma and consequently indicate that expression of this
protein cannot be used as a marker to identify patients at high risk for the subsequent development of
melanoma.