Protein expression of p53 and Rb suppressor genes during the first passages of human endometrial adenocarcinomas heterotransplanted into nude mice.

Five human endometrial adenocarcinomas were heterotransplanted into nude mice to study changes in p53 and Rb protein expression and loss of heterozygosity of these genes during the first nude mice passages. Three of five heterotransplanted tumours were established and measured. In one tumour over-expression of p53 protein was found in passage 1 and subsequently, whereas the original tumour did not over-express the protein. We concluded that the heterotransplantation, i.e. the new host environment, may lead to mutations in the p53 gene. Two tumours from patients and also during nude mice passages expressed p53 protein in two bands, which were probably the result of allele polymorphism. Both p53 and Rb protein expression were increased after growth in estradiol-treated animals. Our results suggest that several changes in the function of these suppressor genes, including mutations, occur during the first passages in nude mice. Consequently, the growth regulation of established tumours may differ from that in their original counterparts in the patients.