Limited role of TP53 and TP53-related genes in myxoid liposarcoma

Aims: Circumstantial evidence suggests that genetic changes may lead to tum or progression within the myxoid liposarcoma tumors (MLTs) carrying non-ran dom chromosomal translocation t(12;16), Methods: To address this subject an immune analysis, applying antibodies against proteins encoded by TP53, MDM 2 and CDK4 genes, complemented by molecular analysis of eight suitable case s, was performed on 104 consecutive cases. Chromosomal translocations were assessed either by cytogenetic analysis or by RT-PCR in 9 suitable cases an d chimeric transcripts were found in all cases but two pleomorphic liposarc omas, Results: Based on immunophenotyping and tumor site, the case material consisted of three groups. The first one was made up of 92 non-retroperito neal cases carrying a null p53, mdm2, cdk4 immunophenotype, which remained unchanged over the time of recurrences and along the gamut of histologic su btypes, The second group was represented by five p53+, mdm2-, cdk4- non-ret roperitoneal cases, 4 of which were further analysed by PCR-SSCP for p53 mu tation. The immunophenotipic profile of these cases, complemented by the mo lecular findings, supported a role of TP53 in tumor progression in three hi gh-grade MLTs, The third group, consisting of 7 retroperitoneal cases, show ed a heterogeneous immunophenotype, sharing immunophenotypic and molecular features with the well-differentiated/evoluted (dedifferentiated) liposarco ma group. Conclusions: TP53 mutations seem to play a role in tumor progress ion in a few cases of MLTs (2.8%) showing more aggressive histologic charac teristics. The unexpected finding that a number of retroperitoneal LMTs dis play the immunophenotypic profile of the well differentiated/evoluted (dedi fferentiated) liposarcomas, deserves further investigation.