Peter M. Glazer

Professor of Therapeutic Radiology and Genetics

B.A. Harvard University, 1979
M.Sc. University of Oxford, 1981
M.D. Yale University, 1987
Ph.D. Yale University, 1987

Research Interests:

Gene targeting and gene therapy
Genetic instability in cancer
Mutagenesis, DNA repair, radiation resistance, and cellular responses to radiation

Honors:

Charles E. Culpeper Scholar in Medical Science 1991-1995
Leukemia Society of America Scholar 1996-2001

Current Research

Gene targeting via triple helix formation.

From an interest in studying cellular DNA repair and recombination pathways, we recognized the utility of DNA triple helix formation as a mechanism for the site-specific introduction of DNA damage in mammalian cells. Using psoralen-conjugated triplex-forming oligonucleotides, we initially demonstrated the feasibility of triplex-targeted mutagenesis in several in vitro systems. Subsequently, we were able to determine conditions under which triplex oligonucleotides could enter cells and efficiently bind to and modify a target site in an SV40 vector within the cells, leading to base pair specific mutations. By employing triplex oligonucleotides to probe repair pathways, we found that third strand formation can block the incision step in nucleotide excision repair. Additional experiments with oligonucleotides not tethered to a reactive agent but capable of high affinity third strand binding revealed that triple helix formation is mutagenic in mammalian cells, inducing mutations by triggering gratuitous transcription-coupled repair. This work has raised the possibility of using triplex formation as a gene knock out modality. It has also suggested that unusual DNA structures may provoke repair activity and may contribute to genomic instability. We are currently studying the feasibility of targeting chromosomal genes using this approach, either by directly inducing mutations in the target gene or by provoking strand breaks which may enhance homologous recombination at the selected site.

DNA repair and mutagenesis in transgenic mice.

We are carrying out mutagenesis studies using a lambda phage vector construct as a chromosomal shuttle vector in transgenic mice and mouse cells. We have determined that p53 overexpression can lessen mutagenesis by UV light, and we have examined the spectrum of x-ray-induced point mutations in mouse cells. In transgenic mice, we have found that locus specific effects can profoundly influence the mutation frequency in a reporter gene, and we have begun to study tissue-dependent variations in the pattern of spontaneous mutagenesis. Recently, we have created doubly transgenic mice carrying not only the lambda shuttle vector for reporting mutations but also a targeted disruption of the mouse PMS2 gene, a homolog of the E. coli mutL gene involved in mismatch repair. The human homolog of this gene has been associated with hereditary colon cancer. We are examining genetic instability in these mice using the lambda vector system. Preliminary work has shown elevated levels of mutation in all tissues tested, in contrast to the limited tissue distribution of cancer in the animals, a difference which highlights the complexity of cancer etiology.

Growth factors and radioresistance.

We have recently determined that overexpression of the insulin like growth factor-1 receptor (IGF-1R) in mouse fibroblasts can confer relative radioresistance. Using a mutational analysis of receptor function, we have found that tyrosine 1251 but not tyrosine 1250 is essential for this effect. We also have begun an analysis of IGF-1 receptor expression in breast cancer biopsy specimens from a series of patients treated at Yale. By comparing patients who recurred in the irradiated breast with a amcthed set who had no recurrence (minimum 10 year follow-up), we have detected a correlation of local recurrence with IGF-1 receptor overexrpression. This finding is consistent with the hypothesis that the IGF-1 pathway plays a role in the response of cells to radiation.

Representative Publications:

Wang, G., Seidman, M.M., and Glazer, P.M. 1996. Mutagenesis in mammalian cells induced by triple helix formation and transcription-coupled repair. Science, 271:802-805.

Reynolds, T.Y., Rockwell, S., and Glazer, P.M. 1996. Genetic instability induced by the tumor microenvironment. Cancer Res. 56:5754-5757.

Narayanan, L., Fritzell, J.A., Baker, S.M., Liskay, R.M. and Glazer, P.M. 1997. Elevated levels of mutation in multiple tissues of mice deficient in the DNA mismatch repair gene, PMS2. Proc. Natl. Acad. Sci. USA 94:3122-3127.

Chan, P.P., Lin, M., Faruqi, A.F., Powell, J., Seidman, M.M., and Glazer, P.M. 1999. Targeted correction of an episomal gene in mammalian cells by a short DNA fragment tethered to a triplex-forming oligonucleotide. J. Biol. Chem. 274:11541-11548.

Faruqi, A.F., Datta, H., Carroll, D., Seidman, M.M., and Glazer, P.M. 2000. Triple-helix formation induces recombination in mammalian cells via a nucleotide excision repair-dependent pathway. Mol. Cell. Biol. 20:990-1000.

Luo, Z., Macris, M.A., Faruqi, A.F., and Glazer, P.M. 2000. High-frequency intrachromosomal gene conversion induced by triplex-forming oligonucleotides microinjected into mouse cells. Proc. Natl. Acad. Sci. USA 97:9003-9008.

Updated 1 September 2000