Dietary iron overload inhibits carbon tetrachloride induced promotion in chemical hepatocarcinogenesis: effects on cell proliferation, apoptosis, andantioxidation

Background/Aims: The aim of this study was to investigate if feeding with c arbonyl iron would facilitate the development of preneoplastic lesions init iated by diethylnitrosamine (DEN) and promoted by CCl4-induced liver cirrho sis. Methods: Male Wistar rats were fed a diet with 1.25%-2.5% carbonyl iron for 23 weeks and received intragastric injections of CCl4 (1.0 or 2.0 ml/kg pe r week) for 13 weeks, followed by one i.p injection of DEN (200 mg/kg), aft er which CCl4 was administered for 8 additional weeks. Animals were killed 48 h after the first CCl4 injection to evaluate liver necrosis, 8 weeks lat er to evaluate fibrosis, and 9 weeks after DEN to determine formation of gl utathione S-transferase 7,7 (GST-7,7) positive foci. Results: Treatment with iron counteracted the increased serum alanine amino transferase levels and liver necrosis following CCl4 administration, Hepati c levels of reduced Q9 and alpha-tocopherol were elevated in rats treated w ith CCl4 and decreased in rats treated with iron compared to the controls. Fibrogenesis was not altered by iron treatment. Nine weeks after DEN initia tion, the number and volume density of GST-7,7-positive foci in rats treate d with CCl4 were significantly increased as compared with controls, but co- treatment with iron inhibited this increase, Apoptotic index was increased in iron-loaded livers, and labelling index (the fraction of S-phase hepatoc ytes) was decreased by cotreatment with iron in livers exposed to CCl4. Conclusion: Carbonyl iron depleted hepatic levels of antioxidants, it decre ased CCl4-induced necrosis and cell proliferation, it enhanced apoptosis an d did not facilitate fibrogenesis. These effects together may explain the s uppression of CCl4-induced promotion after DEN initiation exerted by carbon yl iron in the present study.