An Immunohistochemical Study of mdm - 2 Protein Expression in Malignant Skin Tumors

Cho, Ji Hyeung; Ro, Young Suck

Abstract

BACKGROUND: The human homologue of mouse double minute 2(mdm-2) gene codes for a cellular protein that forms a complex with the mutant and wild type p53 protein and modulates its trans-activation activity. Overexpression of the mdm-2 protein is associated with the tumorigenic potential of mdm-2 gene and overcomes the growth suppressive activity of p53.
OBJECTIVE
& METHODS: In order to investigate the pattern of the mdm-2 and p53 expression in malignant skin tumors, we performed an immunohistochemical analysis using NCL-MDM-2p polyclonal antibody and DO7 monoclonal antibody, respectively, in 10 squamous cell carcinomas (SCCs), 8 basal cell carcinomas(BCCs), 5 malignant melanomas(MMs), and 6 fibrosarcomas (FSs).
RESULTS
The expression of mdm-2 protein was detected in 40% of SCCs, 25% of BCCs, 40% of MMs and 33% of FSs, whereas 40% of SCCs, 25% of BCCs, 20% of MMs, and 17% of FSs showed p53 positivity. One case of SCCs and one case of BCCs showed immunoreactivity with both anti-mdm-2 and anti-p53 antibodies. Within the limitations of this small sample size, there was no relationship between the expression of mdm-2 and p53 protein, as overexpression of these two genes was not mutually exclusive.
CONCLUSION
These findings suggest that interaction between the mdm-2 and p53 genes and products in these malignant tumors appears to be heterogenous and more complex than previously realized. Further studies on molecular basis are required to characterize the mechanism of mdm-2 overexpression and its relation to p53.