DIFFERENCE IN ALLELIC EXPRESSION OF GENES PROBABLY ASSOCIATED WITH TUMOR PROGRESSION IN MURINE FIBROSARCOMAS AND CELL-LINES

Allelic expression was examined by single-strand conformation polymorp hism analysis in murine fibrosarcomas from inter-subspecific F-1 mice between C57BL/6 and MSM. Ten genes encoding p53, mdm2, E-cadherin, 72 kD metalloproteinase and its inhibitor (Timp2), thymidine kinase and f our glucose transporters (Gluts) were examined. These genes were chose n because of their probable association with tumor development and pro gression. In some of the tumors and cell lines, p53, E-cadherin and Gl ut3 genes showed remarkable differences in allelic expression, one all ele being poorly expressed. The allele-specificity persisted in nine c ell lines obtained by repeated transplantations from one tumor. These results suggest that expression of some genes is allele-specific in tu mor cells and the pattern of specificity is stable. Such a decrease or a loss of expression in one of the alleles may be functionally equiva lent to the loss of heterozygosity of the gene, and therefore this may confer malignant properties on tumor cells. It is also suggested that differential expression of two alleles is a common event in tumor cel ls.