Tumor Promoting Iron
in [Hepatitis C]
|
From: ironjustice on 7 Apr 2008 15:57 Neoplastic transformation of rat liver epithelial cells is enhanced by non-transferrin-bound iron Donald J Messner1,2 and Kris V Kowdley2 1Bastyr University, 14500 Juanita Drive, Kenmore, WA 98028, USA 2Benaroya Research Institute and Virginia Mason Medical Center, Seattle, WA 98101, USA BMC Gastroenterology 2008, 8:2doi:10.1186/1471-230X-8-2 Published: 6 February 2008 Abstract Background Iron overload is associated with liver toxicity, cirrhosis, and hepatocellular carcinoma in humans. While most iron circulates in blood as transferrin-bound iron, non-transferrin-bound iron (NTBI) also becomes elevated and contributes to toxicity in the setting of iron overload. The mechanism for iron-related carcinogenesis is not well understood, in part due to a shortage of suitable experimental models. The primary aim of this study was to investigate NTBI-related hepatic carcinogenesis using T51B rat liver epithelial cells, a non- neoplastic cell line previously developed for carcinogenicity and tumor promotion studies. Methods T51B cells were loaded with iron by repeated addition of ferric ammonium citrate (FAC) to the culture medium. Iron internalization was documented by chemical assay, ferritin induction, and loss of calcein fluorescence. Proliferative effects were determined by cell count, toxicity was determined by MTT assay, and neoplastic transformation was assessed by measuring colony formation in soft agar. Cyclin levels were measured by western blot. Results T51B cells readily internalized NTBI given as FAC. Within 1 week of treatment at 200 ìM, there were significant but well-tolerated toxic effects including a decrease in cell proliferation (30% decrease, p < 0.01). FAC alone induced little or no colony formation in soft agar. In contrast, FAC addition to cells previously initiated with N-methyl- N'-nitro-N-nitrosoguanidine (MNNG) resulted in a concentration dependent increase in colony formation. This was first detected at 12 weeks of FAC treatment and increased at longer times. At 16 weeks, colony formation increased more than 10 fold in cells treated with 200 ìM FAC (p < 0.001). The iron chelator desferoxamine reduced both iron uptake and colony formation. Cells cultured with 200 ìM FAC showed decreased cyclin D1, decreased cyclin A, and increased cyclin B1. Conclusion These results establish NTBI as a tumor promoter in T51B rat liver epithelial cells. Changes in cyclin proteins suggest cell cycle disregulation contributes to tumor promotion by NTBI in this liver cell model. Who loves ya. Tom Jesus Was A Vegetarian! http://tinyurl.com/2r2nkh Man Is A Herbivore! http://tinyurl.com/a3cc3 DEAD PEOPLE WALKING http://tinyurl.com/zk9fk |