Detection of p53 gene mutations in human leukemia by PCR-SSCP analysis and direct nucleotide sequencing.
OBJECTIVE: To look for mutations of the p53 gene in leukemic patients and study the relationship between abnormalities in p53 gene and leukemogenesis. METHODS: The peripheral blood and Bone Marrow Samples were collected from 36 patients with various leukemia types including 14 cases of lymphocytic leukemia [8 cases of acute lymphocytic leukemia (ALL), 4 cases of chronic lymphocytic leukemia (CLL), 2 cases of hairy cell leukemia (HCL)] and 22 cases of myelocytic leukemia [11 cases of acute nonlymphocytic leukemia (ANLL), 11 cases of chronic myelocytic leukemia (CML)]. DNA structures of exon 5-8 of the p53 gene were scanned by PCR-SSCP (single strand conformation polymorphism analysis of polymerase chain reaction products). The appropriate DNA fragments were amplified, Purified and sequenced directly. RESULTS: By PCR-SSCP analysis, shifts in electrophoretic mobility of the p53 gene were detected in 3 of 14 patients with lymphocytic leukemia (2 ALL and 1 CLL), but none in 22 patients with myelocytic leukemia including one in blastic crisis. Direct nucleotide sequencing in one patient with ALL showed transition of CTG to CAG at codon 257 of exon 7, resulting in a change of its encoded amino acids from aspartic acid to valine. To our knowledge, the mutation at this codon has not been previously reported hitherto. CONCLUSIONS: The p53 gene mutations are specifically associated with lymphocytic leukemia. Alternations of the p53 gene may play a certain role in leukemogenesis in some cases of lymphocytic leukemia.