P53 OVEREXPRESSION IN HUMAN SOFT-TISSUE SARCOMAS - RELATION TO BIOLOGICAL AGGRESSIVENESS

Background: The tumor suppressor protein p53 is overexpressed in a lar ge fraction of human tumors. It has been supposed that p53 abnormaliti es may be an early event that contributes to the neoplastic transforma tion; alternatively, p53 overexpression might be related to progressio n toward more aggressive tumor phenotypes. The aim of the present work was to better clarify the role of p53 overexpression in human soft ti ssue sarcomas (IISTS). Design: p53 immunohistochemistry analysis using the Pab 1801 was performed in frozen samples of HSTS obtained from 61 patients. Tumors were classified according to the WHO criteria, histo logic grading was based on the criteria of Enzinger and Weiss, and DNA ploidy and S-phase determination was performed by flow cytometrical a nalysis. Results: Of all the HSTS we analyzed, p53 protein overexpress ion occurred more frequently in G3 grade tumors (p < 0.01), HSTS of II I A-B stage (p = 0.02) and in aneuploid tumors (P < 0.01). Conclusions : The association of p53 overexpression with parameters of biological aggressiveness suggests an involvement of p53 in the neoplastic progre ssion of HSTS. This assumption is supported by the findings that in tu mors with a mixed diploid/aneuploid neoplastic cell population p53 pro tein expression was significantly (p < 0.01) higher in the aneuploid c ell subpopulation. In conclusion, our study suggests that overexpressi on of p53 is present mainly in the most biologically aggressive forms of HSTS and may therefore represent a neoplastic progression index pos sibly useful for prognostic purposes.