Exhaustive analysis of the P53 gene coding sequence by denaturing gradient gel electrophoresis: application to the detection of point mutations in acute leukemias.

We report the set-up of a denaturant gradient gel electrophoresis (DGGE) assay to screen for mutations in the whole coding sequence of the p53 gene. These DGGE experimental conditions were applied to the analysis of the p53 gene in acute leukemias. Forty adults with acute myelogenous leukemia (AML) and 21 with acute lymphoid leukemia (ALL) were investigated. Eleven of the AML patients were investigated at the time of the initial diagnosis and at relapse. In contrast with most reports based on amplified fragments analyzed by single-strand conformation electrophoresis and focusing on exons 5 to 8, we analyzed the whole coding sequence of the gene. Two of the 40 AML patients displayed a point mutation in exon 7; it was either an A to G substitution that converted Tyr-234 to Cys, or a G to A change that converted Arg-248 to Gln. The screening procedure led to the discovery of several intronic and exonic polymorphisms. These results confirm the low incidence of p53 mutations in acute leukemias and suggest a limited role of the p53 protein in leukemogenesis. The computerized modeling and electrophoresis parameters presented here provide a powerful tool for the exhaustive characterization of p53 mutants in all kinds of malignancies.