Dietary fish oil deactivates a growth-promoting signaling pathway in hepatoma 7288CTC in buffalo rats

• Published in: Nutrition and cancer 2006-01, Vol.56 (2), p.204-213
• Main Authors: Smith, L.C, Dauchy, E.M, Dauchy, R.T, Sauer, L.A, Blask, D.E, Davidson, L.K, Krause, J.A, Lynch, D.T
• Format: Article
• Language: English
• Subjects: animal disease models; Animals; anticarcinogenic activity; biochemical mechanisms; biochemical pathways; Biological and medical sciences; Carcinoma, Hepatocellular - blood supply; Carcinoma, Hepatocellular - pathology; Cell Division - drug effects; chemoprevention; cyclic AMP; Cyclic AMP - metabolism; dietary fat; Dietary Fats, Unsaturated - metabolism; Dietary Fats, Unsaturated - pharmacology; Diseases of the digestive system; DNA, Neoplasm - metabolism; eicosapentaenoic acid; Epidemiology; fat intake; Fish Oils; free fatty acids; G-proteins; growth-promoting signaling pathway; hepatoma; inhibitors; Linoleic Acids - metabolism; Liver Neoplasms, Experimental - blood supply; Liver Neoplasms, Experimental - pathology; Male; Medical sciences; omega-3 fatty acids; Other treatments; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Random Allocation; Rats; Rats, Inbred BUF; Rats, Sprague-Dawley; Signal Transduction - drug effects; Treatment. General aspects; Tumors
• ISSN: 0163-5581; 1532-7914
• DOI: 10.1207/s15327914nc5602_11

Dietary fish oil decreases growth of solid tumors in rodents. Mechanisms for this effect are not well defined. In rat hepatoma 7288CTC, short-term (1-2 h) treatment with eicosapentaenoic acid during perfusion in situ reduced fatty acid uptake and 3Hthymidine incorporation. To determine if dietary fish oil had this effect in vivo, 48 male Buffalo rats were implanted with tissue-isolated hepatoma 7288CTC and were divided into three groups: Diet I (8% olive oil/2% corn oil), Diet II (6% olive oil/2% corn oil/2% fish oil), or Diet III (3% olive oil/3% corn oil/4% fish oil). When tumors weighed 4 to 6 g rats were anesthetized and tumor fatty acid uptake and 13-hydroxyoctadecadienoic acid release were measured in vivo by arterial minus venous differences. Tumors were analyzed for cyclic adenosine monophosphate (cAMP), DNA content, and 3Hthymidine incorporation. Fish oil feeding significantly (P < 0.05) reduced tumor growth, cAMP content, fatty acid uptake, 13-hydroxyoctadecadienoic acid formation, DNA content, and 3Hthymidine incorporation. Addition of either pertussis toxin or 8-bromoadenosine-cAMP to the arterial blood reversed the inhibitions in tumors in rats fed diet II. These results provide in vivo evidence that dietary fish oil suppressed a specific linoleic acid-dependent, inhibitory G protein-coupled, growth-promoting signaling pathway in rat hepatoma 7288CTC.