title: Gene expression profiling distinguishes between spontaneous and radiation-induced rat mammary carcinomas.
abstract: The ability to distinguish between spontaneous and radiation-induced cancers in humans is expected to improve the resolution of estimated risk from low dose radiation. Mammary carcinomas were obtained from Sprague-Dawley rats that were either untreated (n = 45) or acutely gamma-irradiated (1 Gy; n = 20) at seven weeks of age. Gene expression profiles of three spontaneous and four radiation-induced carcinomas, as well as those of normal mammary glands, were analyzed by microarrays. Differential expression of identified genes of interest was then verified by quantitative polymerase chain reaction (qPCR). Cluster analysis of global gene expression suggested that spontaneous carcinomas were distinguished from a heterogeneous population of radiation-induced carcinomas, though most gene expressions were common. We identified 50 genes that had different expression levels between spontaneous and radiogenic carcinomas. We then selected 18 genes for confirmation of the microarray data by qPCR analysis and obtained the following results: high expression of Plg, Pgr and Wnt4 was characteristic to all spontaneous carcinomas; Tnfsf11, Fgf10, Agtr1a, S100A9 and Pou3f3 showed high expression in a subset of radiation-induced carcinomas; and increased Gp2, Areg and Igf2 expression, as well as decreased expression of Ca3 and non-coding RNA Mg1, were common to all carcinomas. Thus, gene expression analysis distinguished between spontaneous and radiogenic carcinomas, suggesting possible differences in their carcinogenic mechanism.
authors.affiliation: Experimental Radiobiology for Children's Health Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences. t_imaoka@nirs.go.jp
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Imaoka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nishimura
authors.forename: Shizuko
authors.initials: S
authors.lastname: Kakinuma
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Ushijima
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Shimada
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis*; D004307:Dose-Response Relationship, Radiation; D020869:Gene Expression Profiling; D008325:Mammary Neoplasms, Experimental / Q000145:classification* / Q000209:etiology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000032:analysis*; D009381:Neoplasms, Radiation-Induced / Q000145:classification* / Q000378:metabolism*; D011829:Radiation Dosage; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins