DOE Low Dose Radiation Research Program Workshop I Abstracts November 10-12, 1999, Washington, D.C.

9. Development of a Functional Genomics Approach Employing Radiation-Induced Changes in Gene Expression to Monitor Cells after Low Dose and Low Dose-Rate Exposures

Albert J. Fornace Jr., Sally A. Amundson, Jeff Trent, and Paul Meltzer
37-5C09 National Institutes of Health, Bethesda, MD 20892-4255
amundson@box-a.nih.gov

Summary: This project explores the utility of gene induction as a means to monitor for exposure to ionizing radiation; molecular biology approaches, including recently developed cDNA chip technology, are employed to study cellular responses to radiation injury.

Abstract: Using a human myeloid tumor cell line (ML-1), we have demonstrated induction of mRNA expression of several stress responsive genes by doses of gamma rays as low as 2 cGy. For instance, the dose-response for induction of CIP1/WAF1 and GADD45 appears to be linear over the range of 2 - 50 cGy, and shows no evidence of a threshold for induction. Although 2 and 5 cGy exposures did not result in any detectable reduction in cloning efficiency or increased apoptosis in ML-1 cells, these exposures did produce a brief cell cycle delay. We have also used fluorescent cDNA microarray hybridization to investigate transcriptional stress responses following low doses of gamma-rays, and to identify additional radiation-responsive genes for inclusion on a stress-specific microarray we are developing. Using this functional genomics approach, the responses of a substantial portion of a cell's expressed genes can be monitored. As a first step to in vivo studies in humans, the ionizing radiation responses of peripheral blood lymphocytes (PBL) irradiated ex vivo are being characterized. Future studies will be expanded to responses in irradiated mice using the same approaches. Computation-intensive informatics analysis methods are also being developed for management of the complex gene expression profiles resulting from these experiments, and some preliminary results are illustrated. This functional genomics approach should have utility for DOE priorities in radiobiology and toxicology.

Amundson, S.A., Bittner, M., Yidong, C., Trent, J., Meltzer, P., and Fornace, A.J., Jr. Fluorescent cDNA microarray hybridization reveals complexity and heterogeneity of cellular genotoxic stress responses. Oncogene 18: 3666-3672, 1999.

Amundson, S. A., Do, K. T., and Fornace, A.J., Jr. Induction of Stress Genes by Low Doses of Gamma Rays. Radiat Res 152: 225-231, 1999.

Fornace, A.J., Jr., Amundson, S.A., Bittner, M., Myers, T.G., Weinstein, J.N., Meltzer, P., and Trent, J. The complexity of radiation stress responses: analysis by informatics and functional genomics approaches. Gene Expression, 7: 387-400, 1999.