Comparative effects of omega-3 and omega-6 polyunsaturated fatty acids on protein metabolism in rats bearing the mammary adenocarcinoma.
The comparative effects of diets containing 20% (wt/wt) of either fish oil (FO) or safflower oil (SO) on protein synthesis and catabolism were determined in rats bearing the 7,12-dimethylbenz(a)anthracene (DMBA) 13762 mammary adenocarcinoma in vivo using a 6-hour constant infusion of L-(1-14C)-leucine. Tumor-bearing animals fed FO had significantly lower tumor growth rate (36 +/- 0.5 v 53 +/- 0.7%/d, P less than .05), total tumor protein synthesis (Ts) (1.25 +/- 0.1 v 1.85 +/- 0.1 mumol/h, P less than .05), and tumor protein concentration (12.0 +/- 0.5 v 14.0 +/- 0.7%/d, P less than 0.01). Tumor fractional synthetic rate and total protein breakdown rate of the tumor were unaffected by FO feeding. Both tumor-bearing and saline-control animals fed FO had significantly (P less than .01) lower liver fractional synthetic rate and total protein breakdown rate, and higher liver total protein compared with SO-fed rats. Muscle protein kinetics were unaffected by either treatment or diet. Whole body protein kinetics were not affected by dietary treatment, but the presence of tumor significantly (P less than .001) reduced whole body flux, synthesis, breakdown, and oxidation. Chronic FO feeding for 7 weeks significantly (P less than .001) lowered omega-6 polyunsaturated fatty acids (omega-6 PUFAs) and significantly elevated omega-3 polyunsaturated fatty acids (omega-3 PUFAs) (P less than .001) in both plasma phospholipid and triglycerides. The present study indicates that dietary FO can modulate mammary tumor growth in a manner that reflects changes in protein metabolism in both host and tumor tissues.
Wan
J M
JM
Cancer Research Institute, New England Deaconess Hospital, Boston, MA 02115.
Istfan
N W
NW
Chu
C C
CC
Blackburn
G L
GL
Bistrian
B R
BR
D015127:9,10-Dimethyl-1,2-benzanthracene; D000230:Adenocarcinoma / Q000098:blood supply / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D002250:Carbon Radioisotopes; D004041:Dietary Fats / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D005395:Fish Oils / Q000494:pharmacology; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011865:Radioisotope Dilution Technique; D051381:Rats; D011916:Rats, Inbred F344; D012039:Regional Blood Flow; D012450:Safflower Oil / Q000494:pharmacology
D002250:Carbon Radioisotopes; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D009124:Muscle Proteins; D011506:Proteins; D015127:9,10-Dimethyl-1,2-benzanthracene; D012450:Safflower Oil; D007930:Leucine