Evidence for the presence of large-scale deletion mutations in a murine tumour model.

Abstract

In order to study mutagenicity occurring within a tumour environment, our lab has developed the Mutated murine tumour model, which is able to sensitively detect mutations at a genetically manipulated hprt locus. Prior to my work, the X-linked hprt gene in the Mutated cell lines was thought to be heterozygous based on high sensitivity to induction of mutations by ionizing radiation and the identification of 3 X-chromosomes by fluorescent in situ hybridization. In order to determine the hprt genotype and to confirm that the hprt gene was indeed heterozygous, the hprt cDNA of Mutated cells was cloned and sequenced. Three mRNA species were identified: mRNA-A corresponds to wild type hprt, mRNA-B contains a single nucleotide deletion within exon 3, and mRNA-C contains a deletion of exons 2 and 3. In order to identify the types of mutations that are generated during in vivo tumour growth, a screening method was devised to analyze mutations occurring in the wild type hprt gene. (Abstract shortened by UMI.)