ABSENCE OF MUTATIONS IN THE HIGHEST MUTABILITY REGION OF THE P53 GENEIN TUMOR-DERIVED CHEF18 CHINESE-HAMSTER CELLS

A series of independent tumour-derived Chinese hamster CHEF18 cell lin es was analyzed for the presence of mutations in the cDNA region (exon s 5-9) of the p53 gene, where the great majority of p53 mutations of h uman tumours accumulate. Since the gene is highly conserved among spec ies, we used two primers designed on the basis of the human cDNA seque nce to isolate the cDNA region from total RNA of Chinese hamster cells , The amplified fragments of 614 bp were digested with cleavase I endo nuclease and fragment length polymorphism analysis showed that the res triction pattern of the p53 exons 5-9 region of tumour-derived cell li nes was identical to that of diploid Chinese hamster CHL fibroblasts. Sequencing of the amplified fragments showed 100% homology between seq uences, which demonstrated the absence of p53 mutations in the exons 5 -9 cDNA region expected to have the highest mutability. Nevertheless, the antibody DO-7 recognized the presence of a stabilized p53 protein only in tumour-derived cell lines, which indicated that p53 expression correlated with transformed status.