Differential gene expression induced by ionizing radiation in normal and ataxia telangiectasia fibroblast cell lines

SS Mello BCa, RS Cardoso MSca, GAS Passos PhDa,b and ET Sakamoto-Hojo PhDa,c

aDepartamento de Genetica, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo. bGrupo de Imunogenetica Molecular, Departamento de Genetica, FMRP-USP. cDepartamento de Biologia, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto-USP, Ribeirao Preto, S.P., BRASIL;

AIM: Ionizing radiation induces signal transduction pathways, and the disruption of a signaling cascade may contribute to radiation sensitivity, as in the case of ataxia telangiectasia (AT) syndrome. The objective of the present work was to compare gene expression profiles in normal and AT cell lines after exposure to gamma-rays. METHODS: cDNA clones were arranged on nylon membranes (cDNA-macroarray method) to study the differential expression profiles of 192 genes in human SV-40 transformed fibroblast cell lines, MRC-5 (normal cells) and AT5BIVA (AT cells). Exponentially growing cells were irradiated (2 Gy) and cDNA complex probes were prepared from RNA extracted after 1, 6, 9 and 24 h. RESULTS: Many genes were found differentially expressed (>2-fold) in both cell lines. While p53 gene was highly expressed at 9 h after irradiation in MRC-5 cells, AT-5BIVA cells showed increased expression at 24h. ATM gene was highly expressed at earlier time (1 h) in AT-5BIVA than MRC-5 cells, while cell cycle control genes (CDKN2C, CDKi2A) were highly expressed at later time (6, 9 or 24 h) in AT, but at earlier time (1 and 6 h) in MRC-5 cells. DNA repair genes (ERCC5, XRCC1, hMS3 and XP-C) were expressed at earlier times (1 and 9 h) in both cell lines. CONCLUSIONS: The expression profiles differed between both cell lines, but depending on the classes of genes. These results are important to study the complex signaling mechanism of cellular response to radiation-induced DNA damage.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Gene Expression, Part 2.