NO CORRELATION OF C-MYC OVEREXPRESSION AND P53 MUTATIONS IN LIPOSARCOMAS

Although it is well known that oncogenesis is a multistep process invo lving the activation of normal cellular genes to become oncogenes and/ or the inactivation of tumor suppressor genes, this process has seldom been investigated in soft tissue tumours. We screened a group of 36 l iposarcomas for genetic abnormalitis in the p53 tumour suppressor gene and c-myc oncogene. Altered c-myc gene expression was examined by dif ferential RT-PCR assay. p53 Gene mutations in exons 4-8 were analysed by using PCR-SSCP analysis and direct sequencing. Elevated c-myc expre ssion was found in 6 of 31 liposarcomas (19.4%). p53 Gene mutations we re observed in 5 of 36 liposarcomas (13.9%). Both genetic alterations were associated with the histological subtype of liposarcomas. Whereas c-myc gene expression was a characteristic of myxoid/round cell lipos arcomas, p53 gene mutations were found more frequently in pleomorphic variants. Liposarcomas of the well-differentiated subtype showed neith er p53 gene mutations nor altered c-myc gene expression. Our results i ndicate that the c-myc oncogene and the p53 tumor suppressor gene do n ot seem to cooperate in the oncogenesis of liposarcomas.