Mutation analysis of coding sequences of the entire transforming growth factor beta type II receptor gene in sporadic human colon cancer using genomic DNA and Intron primers

Mutations in the transforming growth factor beta type II receptor (TGF beta RII) gene have been detected in several human cancers exhibiting microsatellite instability. To extend analyses of this gene, we previously investigated the exon-intron organization of the TGF beta RII. gene and defined seven exons and flanking intron sequences. In this study, we further determined the nucleotide sequences surrounding these seven exons and designed eight sets of intron-based primers to examine the entire coding region of the TGF beta RII gene. Using these primers, we screened genomic DNA sequences from 30 sporadic colorectal cancers for mutations of the TGF beta RII. gene. TGF beta RII mutations were detected in two of 30 tumors and both displayed microsatellite instability. One had a deletion in a polyadenine tract in exon 3 and the other had a point mutation in the kinase domain located in exon 7. There were no mutations in exons 1, 2, 4, 5 and 6. These results further implicate the polyadenine tract and kinase domain as mutational hotspots in the TGF beta RII gene in cells,vith genomic instability and suggest that TGF beta RII gene mutations occur rarely in cells lacking genomic instability.