Biochemical alterations in 7,12-dimethylbenz[a]anthracene-induced mammary tumors from rats subjected to caloric restriction.
Caloric restriction reduces the incidence and progression of a broad spectrum of neoplastic diseases, yet little is known about the biochemical and molecular mechanisms involved. Profiles of enzyme activities of importance in cellular energy utilization were examined in 7,12-dimethylbenz[a]anthracene-induced (DMBA) mammary adenocarcinomas from rats fed ad libitum or calorically restricted diets. The diets provided equal nutrients except for fewer carbohydrate-derived calories; graded caloric restriction was 10, 20, 30 and 40%. The specific activities of hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, malic enzyme and fructose-1,6-bisphosphatase were all elevated to varying degrees in both large palpable and small, non-palpable tumors from calorically restricted hosts compared to activities in tumors from ad libitum-fed rats. Phosphofructokinase activity was increased in palpable tumors from calorically restricted hosts but markedly reduced in non-palpable tumors. These results suggest adaptive or compensatory alterations in tumor enzyme profiles in response to the altered nutritional state of the host.
D015127:9,10-Dimethyl-1,2-benzanthracene; D000230:Adenocarcinoma / Q000139:chemically induced / Q000201:enzymology*; D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000201:enzymology; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology*; D011770:Pyruvate Kinase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D004040:Dietary Carbohydrates; D015127:9,10-Dimethyl-1,2-benzanthracene; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D006593:Hexokinase; D011770:Pyruvate Kinase; D006597:Fructose-Bisphosphatase