MOLECULAR ABNORMALITIES OF THE P53 PATHWAY IN DEDIFFERENTIATED LIPOSARCOMA

Dedifferentiated liposarcoma represents a distinct subtype of liposarc oma and is characterized by the presence of abrupt transition from wel l-differentiated liposarcoma to high-grade pleomorphic sarcoma (mostly MFH-like). A key role for p53 in tumour progression of this subset of liposarcomas has been suggested on the basis of p53 immunopositivity, A series of 14 dedifferentiated liposarcomas has been investigated by analysing the p53 gene and protein together with the p53-related mole cules p21(Waf1) and mdm2, to verify whether the p53 pathway is involve d in the development and progression of this tumour type, The results indicate that the p53 gene is rarely involved in dedifferentiated lipo sarcoma (7 per cent of cases analysed) and that low percentages of p53 immunopositivity are still compatible with integrity of the p53 gene. This concept is also supported by the observed preservation of p21(Wa f1) immunoreactivity in all but the p53-mutated cases. By contrast, md m2 overexpression emerges as the most frequent abnormality in dediffer entiated liposarcoma (57 and 78 per cent of cases in well-dedifferenti ated and high-grade areas, respectively).