Infrequent somatic mutations of the p73 gene in various human cancers

Aims: It has already been reported that loss of heterozygosity (LOH) on chr omosome Ip is frequent in a variety of human cancers. This finding implies the presence of some important tumour suppressor genes in this region, p73. a candidate tumour suppressor gene identified recently in chromosome band 1p36.33, encodes a protein highly homologous to p53. To investigate the rol e of the p73 gene in human carcinogenesis, we studied genetic alterations o f this gene in various human cancers. Methods: We analysed the entire coding exons as Hell as their surrounding e xon-intron boundaries of the p73 gene in 185 cases of various types of tumo urs (47 breast cancers, 43 colorectal cancers, 31 gastric cancers, 23 neuro blastomas. 21 lung cancer cell Lines, and 20 pancreatic cancer cell lines): they are known as a group of tumours with frequent LOHs in the Ip region. PCR-SSCP analysis was performed and rumours in which aberrant migrating siz ed bands wore observed were subjected to direct sequencing analyses. Results: Of the 185 cases, only one somatic mis-sense mutation of glutamine From arginine at codon 269 in exon 7 was found in one breast cancer. In ad dition, several polymorphisms were found at codons 137. 336, 349, and 610, as well as in introns 6. 8, and 9. Monoallelic expression was also observed in pancreatic cancer cell lines, Conclusions: Our results suggest that inactivation of the p73 gene does not play a major role in the tumour types analysed in the present study.