title: Gene signaling pathways mediating the opposite effects of prepubertal low-fat and high-fat n-3 polyunsaturated fatty acid diets on mammary cancer risk.
abstract: In rats, prepubertal exposure to low-fat diet containing n-3 polyunsaturated fatty acids (PUFA) reduces mammary cell proliferation, increases apoptosis, and lowers risk of mammary tumors in adulthood, whereas prepubertal high-fat n-3 PUFA exposure has opposite effects. To identify signaling pathways mediating these effects, we performed gene microarray analyses and determined protein levels of genes related to mammary epithelial cell proliferation. Nursing female rats and rat pups were fed low-fat (16% energy from fat) or high-fat (39% energy from fat) n-3 or n-6 PUFA diets between postnatal days 5 and 24. cDNA gene expression microarrays were used to identify global changes in the mammary glands of 50-day-old rats. Differences in gene expression were confirmed by real-time quantitative PCR, and immunohistochemistry was used to assess changes in the peroxisome proliferator-activated receptor gamma and cyclin D1 levels. DNA damage was determined by 8-hydroxy-2'-deoxyguanosine assay. Expressions of the antioxidant genes thioredoxin, heme oxygenase, NADP-dependent isocitrate dehydrogenase, and metallothionein III, as well as peroxisome proliferator-activated receptor gamma protein, were increased in the mammary glands of 50-day-old rats prepubertally fed the low-fat n-3 PUFA diet. Prepubertal exposure to the high-fat n-3 PUFA diet increased DNA damage and cyclin D1 protein and reduced expression of BRCA1 and cardiotrophin-1. Reduction in mammary tumorigenesis among rats prepubertally fed a low-fat n-3 PUFA diet was associated with an up-regulation of antioxidant genes, whereas the increase in mammary tumorigenesis in the high-fat n-3 PUFA fed rats was linked to up-regulation of genes that induce cell proliferation and down-regulation of genes that repair DNA damage and induce apoptosis.
authors.affiliation: Cancer Prevention Fellowship Program, Office of Preventive Oncology, Division of Cancer Prevention, National Cancer Institute/NIH, Bethesda, MD 20892, USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Olivo-Marston
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Richard Y
authors.initials: RY
authors.lastname: Lee
authors.forename: Anna
authors.initials: A
authors.lastname: Cabanes
authors.forename: Galam
authors.initials: G
authors.lastname: Khan
authors.forename: Alan
authors.initials: A
authors.lastname: Zwart
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.forename: Robert
authors.initials: R
authors.lastname: Clarke
authors.forename: Leena
authors.initials: L
authors.lastname: Hilakivi-Clarke
mesh_terms: D000818:Animals; D019938:Cyclin D1 / Q000187:drug effects; D004032:Diet; D018752:Diet, Fat-Restricted; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D051547:Heme Oxygenase-1 / Q000187:drug effects; D007150:Immunohistochemistry; D007521:Isocitrate Dehydrogenase / Q000187:drug effects; D008321:Mammary Glands, Animal / Q000187:drug effects*; D008325:Mammary Neoplasms, Experimental / Q000209:etiology*; D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D047495:PPAR gamma / Q000187:drug effects; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D015398:Signal Transduction / Q000235:genetics*; D013879:Thioredoxins / Q000187:drug effects
chemical_list: D005231:Fatty Acids, Unsaturated; D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins; D047495:PPAR gamma; D019938:Cyclin D1; D013879:Thioredoxins; D007521:Isocitrate Dehydrogenase; D051547:Heme Oxygenase-1