In rat models of mammary carcinogenesis, the highest incidence of carcinomas occurs when the animals are exposed to carcinogens during puberty (typically postnatal day 50). Gene expression analysis of rat mammary gland in Sprague-Dawley rats revealed a consistent down-regulation of Krebs cycle genes in tissues from 50-day old animals relative to 21-day animals. This result was confirmed at the protein level by Western blot analysis and assessment of specific activity of selected Krebs cycle enzymes; succinate dehydrogenase (SDH)-B, fumarase (FH), NAD+ isocitrate dehydrogenase (IDH3A) were significantly reduced at late puberty (day 50) compared with prepubertal (day 21) in the mammary gland. A nanoLC-multiple reaction ion monitoring-mass spectrometry method was developed that measures each of these proteins in a single assay in tissue and mitochondrial preparations. The results reported here support the gene expression data obtained by microarray analysis and suggest that the increased vulnerability of the rat mammary gland at late puberty to breast cancer-inducing carcinogens is correlated with an overall down-regulation of aerobic metabolism. Supported by NCI U54 CA100949.
Evolution of the Krebs cycle during the prepubertal-pubertal transition in rat mammary gland
PIRAS, ANTONIO;
2009-01-01
Abstract
In rat models of mammary carcinogenesis, the highest incidence of carcinomas occurs when the animals are exposed to carcinogens during puberty (typically postnatal day 50). Gene expression analysis of rat mammary gland in Sprague-Dawley rats revealed a consistent down-regulation of Krebs cycle genes in tissues from 50-day old animals relative to 21-day animals. This result was confirmed at the protein level by Western blot analysis and assessment of specific activity of selected Krebs cycle enzymes; succinate dehydrogenase (SDH)-B, fumarase (FH), NAD+ isocitrate dehydrogenase (IDH3A) were significantly reduced at late puberty (day 50) compared with prepubertal (day 21) in the mammary gland. A nanoLC-multiple reaction ion monitoring-mass spectrometry method was developed that measures each of these proteins in a single assay in tissue and mitochondrial preparations. The results reported here support the gene expression data obtained by microarray analysis and suggest that the increased vulnerability of the rat mammary gland at late puberty to breast cancer-inducing carcinogens is correlated with an overall down-regulation of aerobic metabolism. Supported by NCI U54 CA100949.
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