Development of Yeast as an In Vivo Test Tube to Characterize a Broad Spectrum of p53 Mutations Associated with Breast Cancer
Final rept. 1 Oct 2001-30 Sep 2002
NATIONAL INST OF ENVIRONMENTAL HEALTH SCIENCES RESEARCH TRIANGLE PARK NC
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The p53 tumor suppressor protein is an inducible, sequence-specific transcription factor capable of modulating the expression of more than 100 genes in human cells to coordinate different cellular responses to stress. The p53 pathway is altered in nearly all human cancers and p53 mutant proteins with amino acid changes in the DNA binding domain are aberrantly expressed in nearly 50 of tumors. We developed a system in the yeast Saccharomyces cerevisiae that addresses p53 transactivation capacity from 26 different p53 Response Elements REs in a constant chromatin structure and that provides for detailed functional analysis of p53 mutant alleles. We applied this method in trying to elucidate the mechanisms that regulate differential transactivation by p53 and determined the functional fingerprints of many p53 mutants including a group of novel alleles that were reported in familial breast cancer. Interestingly, we observed that among 1300 different amino acid changes detected in tumors, many do not result simply in loss of function but instead alter the ability to transactivate from the various target sequences. Our results suggest that the actual functional status of p53 alleles expressed in tumor cells, not simply whether or not there is a mutation, may correlate with clinical outcome. The yeast functional assay offers a practical means to develop ap53 mutant functionality database that is likely to become valuable in predicting tumor aggressiveness and responsiveness to therapy.
- Genetic Engineering and Molecular Biology
- Anatomy and Physiology
- Medicine and Medical Research