Methylation profile and amplification of proto-oncogenes in rat pancreas induced with phytoestrogens.
Specific gene hypermethylation has been shown in DNA from neonatal rats exposed to the phytoestrogens, coumestrol, and equol. The pancreas is an organ in which estrogen receptors have been shown to be present. Studies have correlated the development of acute pancreatitis with rising levels of human estrogen binding proteins. Neonatal rats were dosed with 10 or 100 micrograms of coumestrol or equol on postnatal day (PND) 1-10. The animals were sacrificed at Day 15. The pancreas was excised and pancreatic acinar cells isolated for molecular analysis. DNA was isolated from the cells by lysis in TEN-9 buffer supplemented with proteinase K and 0.1% SDS. High molecular weight (HMW) DNA was digested with the methylated DNA specific restriction enzymes, Hpa II and Msp I, for determination of methylation profiles. Both coumestrol and equol at high doses caused hypermethylation of the c-H-ras proto-oncogene. No hypermethylation or hypomethylation was observed in the proto-oncogenes, c-myc or c-fos. Methylation is thought to be an epigenetic mechanism involved in the activation (hypomethylation) or inactivation (hypermethylation) of cellular genes which are known to play a role in carcinogenesis. Epidemiology studies have shown that equol may have anti-carcinogenic effects on some hormone-dependent cancers. Additional studies are needed to further understand the role of phytoestrogens and methylation in relation to pancreatic disorders.
Lyn-Cook
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BD
Division of Nutritional Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079-9502.
Blann
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E
Payne
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PW
Bo
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J
Sheehan
D
D
Medlock
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K
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002839:Chromans / Q000494:pharmacology; D003375:Coumestrol / Q000494:pharmacology; D004247:DNA / Q000378:metabolism*; D019003:Deoxyribonuclease HpaII; D015252:Deoxyribonucleases, Type II Site-Specific; D060754:Equol; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D005260:Female; D005784:Gene Amplification / Q000187:drug effects*; D011905:Genes, ras / Q000235:genetics*; D007529:Isoflavones; D008745:Methylation / Q000187:drug effects; D010179:Pancreas / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D048789:Phytoestrogens; D028321:Plant Preparations; D000090063:Proto-Oncogene Mas; D051381:Rats; D017207:Rats, Sprague-Dawley
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D002839:Chromans; D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; C000715470:MAS1 protein, human; D048789:Phytoestrogens; D028321:Plant Preparations; D000090063:Proto-Oncogene Mas; D060754:Equol; D004247:DNA; D019003:Deoxyribonuclease HpaII; D015252:Deoxyribonucleases, Type II Site-Specific; D003375:Coumestrol