An Immunohistochemical Study of pRb, p16, p53 and p21 Protein Expression in Malignant Melanoma

Chang, Sung Eun; Kim, Hyun Soo; Park, Il Jung; Choi, Jee Ho; Sung, Kyung Jeh; Moon, Kee Chan; Koh, Jai Kyoung

Abstract

BACKGROUND: The proteins regulating the cell growth cycle such as the products of rb, p53, p16 and p21 genes are recently believed to have a role in various tumorigenesis.
OBJECTIVE
The purpose of this study was to investigate an expression pattern and a role of p53, pRb, p16, and p21 in the pathogenesis of non-metastatic malignant melanomas.
METHODS
Immunohistochemical study of p53, pRb, p16, and p21 was done in 10 invasive non-metastatic malignant melanomas compared to 5 benign melanocytic nevi. Standard streptavidin- biotin peroxidase method using the monoclonal antibodies was used.
RESULTS
pRb was positive in all malignant melanomas tested. p16 was positive in 100% of benign nevi and only 40% of the malignant melanomas showed loss of p16 protein. p53 was positive in only 30% of malignant melanomas. p21 expression was seen diffusely in 70% of the malignant melanomas. In benign nevi, significant reactivity of p53, pRb, and p21 was not shown.
CONCLUSION
In non-metastatic malignant melanomas, rb gene is not likely to be deleted and the overexpression of pRb might from activation of pRb protein facilitating cell cycle progression. In non-metastatic malignant melanomas, neither loss of p16 nor p53 overexpression was not frequent as previous reports of metastatic malignant melanomas. p21 overexpression in malignant melanomas might be related to invasiveness of malignant melanoma.