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METHYL METHANESULFONATE-INDUCED GENE EXPRESSION CHANGES IN HUMAN SKIN FIBROBLASTS
Citation:
Knapp, G W., A H. Tennant, AND R D. Owen. METHYL METHANESULFONATE-INDUCED GENE EXPRESSION CHANGES IN HUMAN SKIN FIBROBLASTS. Presented at GEMS fall meeting, Chapel Hill, NC, 11-05-03.
Description:
METHYL METHANESULFONATE-INDUCED GENE EXPRESSION CHANGES IN HUMAN SKIN FIBROBLASTS. Geremy W. Knapp, Alan Tennant, and Russell D. Owen. Environmental Carcinogenesis Division, National Health and Environmental Effects Research Laboratory, U. S. Environmental Protection Agency, Research Triangle Park, NC 27711.
DNA damage repair mechanisms serve an essential role in preserving genome stability. Differences in the ability and/or the efficiency of DNA damage repair can contribute to varying cancer susceptibilities due to the accumulation of damage over time. It has been hypothesized that increased susceptibility to cancer in young children is attributed to differences in DNA repair enzymes. To examine potential age-related gene transcription effects caused by DNA damaging agents, human skin fibroblasts were treated with 1mM methyl methanesulfonate (MMS). The fibroblasts were derived from 5 month old and 10 year old human donors. Real Time and Quantitative RTPCR (RTAQ-RTPCR) was used to measure gene expression changes in putative MMS-responsive and DNA repair genes. Expression levels of MMS-responsive Mif1 and Mif2 (van Laar et. al., 2000) increased with time exceeding 7.5-fold and 4.5-fold induction at 4 hours in the cell lines derived from the 5 month old and 10 year old, respectively. Expression levels of p21 and p53, genes associated with DNA repair, also increased with time exceeding a 7-fold and 2-fold induction at 4 hours in the 5 month old and 10 year old derived cell lines, respectively. The cell line derived from the 10 year old donor exhibited a delayed response when compared with the five month old for Mif1, Mif2, p21, and p53. The maximal response in the 5 month old derived cell line occurred at 4 hours with a drop in expression at 8 hours though remaining elevated over control levels. At 8 hours the 10 year old derived cell line expression levels achieved maximal response. These differences in expression response and timing may have important implications for the susceptibility of the cell to accumulate DNA damage and ultimately may affect damage repair efficiency, as a function of age. [This abstract does not necessarily reflect EPA policy]