Mutation spectrum of the p53 gene in bone and soft tissue sarcomas

We present here an analysis of the spectrum of mutations of the p53 gene seen in 127 bone and soft tissue sarcomas of various histological classifications. Gross rearrangements were analyzed by Southern blotting using a complementary DNA probe from the p53 gene, and subtle alterations in the entire coding sequence (exons 2 through 11) were identified by a combination of single-strand conformation polymorphism analysis and direct genomic sequencing. A total of 42 somatic alterations of the p53 gene were found, of which 21 were gross rearrangements and 21 were subtle alterations. These included 17 cases of a single base substitution, 3 small deletions, and one single base insertion. In contrast to reported findings for other types of cancer, we found that mutations of the p53 gene in sarcomas are quite heterogeneous both in their distribution throughout the gene and in the type of genetic alterations that result. All 13 missense mutations we found occurred at highly conserved residues, whereas 8 nonsense mutations occurred at sites that spanned the gene from codons 46 to 316. Surprisingly, approximately one-half of the osteosarcomas with allelic deletions on 17p did not have detectable alterations in the coding sequence of the p53 gene.