Lipid metabolism and enzyme activities in hormone-dependent and hormone-independent mammary adenocarcinoma in GR mice.
Lipid metabolism in hormone-dependent (HD) GR mouse mammary tumors was compared to that in hormone-independent (HI) tumors and normal mammary tissues. HD tumors, like normal mammary tissue but unlike HI tumors, synthesized medium-chain-length fatty acids (MCFA). However, when treated with hormones (estrone and progesterone), the HI tumors were induced to produce MCFA. The activity of thioesterase II correlated positively with the synthesis of MCFA and was influenced by the hormones administered. The activities of NADP+-linked malate dehydrogenase, citrate lyase, acetyl-CoA carboxylase, and fatty acid synthetase, although lower in tumors than in normal glands, were not different in HD as compared to HI tumors. Whereas the predominating lipids synthesized in normal glands were triglycerides, phospholipids comprised about half of the lipid synthesized in the tumors, with no difference between HD and HI tumors. The conversion of D-[U-14C]glucose to 14CO2 was higher in HD tumors than in HI tumors but increased in HI tumors treated with hormones in vivo. By a comparison of the 14CO2 produced from D-[1-14C]glucose and from D-[6-14C]glucose in the presence and absence of an electron acceptor (methylene blue), it was demonstrated that regeneration of NADP+ from NADPH was a rate-limiting step for the pentose phosphate pathway in the tumors. Hence, while differences in the lipid metabolism can be demonstrated between HD and HI GR mouse mammary tumors, some of the changes are due to the hormone treatment rather than to a specific alteration in the tumor itself.
D000230:Adenocarcinoma / Q000378:metabolism*; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D004970:Estrone / Q000494:pharmacology; D064429:Fatty Acid Synthases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D007774:Lactation; D050356:Lipid Metabolism; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D009376:Neoplasms, Hormone-Dependent / Q000378:metabolism*; D010084:Oxidation-Reduction; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology; D013869:Thiolester Hydrolases / Q000378:metabolism
D005227:Fatty Acids; D002245:Carbon Dioxide; D004970:Estrone; D011374:Progesterone; D005954:Glucosephosphate Dehydrogenase; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II; D005947:Glucose