Carcinogenesis Advance Access published online on April 24, 2003
Carcinogenesis, doi:10.1093/carcin/bgg053
© 2003 by Oxford University Press
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MOLECULAR EPIDEMIOLOGY AND CANCER PREVENTION
1 Division of Pathology, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501
* Corresponding author. E-mail: umemura{at}nihs.go.jp.
Received 18 February 2003
; revised 13 March 2003
; accepted 20 March 2003
In order to explore a possibility that the custom of drinking green tea infusion is efficacious for reducing the carcinogenic risk of environmental exposure to pentachlorophenol (PCP), we examined the effects in a hepato- and cholangio-carcinogenesis model in mice exposed to DEN. In the first experiment, groups of 15 male mice were initially treated with diethylnitrosamine (DEN) at a dose of 20 ppm in the drinking water for the first 8 weeks followed a 4 week recovery interval by PCP at concentrations of 0 (basal diet), 300 or 600 ppm in the diet for 23 weeks. Further groups of animals were treated with DEN and PCP in the same manner and received 2% green tea infusion (GT) instead of the drinking water from week 10 until the final sacrifice. PCP exposure at the high dose promoted DEN-induced hepatocarcinogenesis, and also caused progression of cystic hyperplasias of the intrahepatic bile ducts to cholangiocellular tumors. Co-administration of GT was able to prevent the increases of incidences and multiplicities of DEN-induced hepatocellular tumors and also arrest the progression of cholangiocellular tumors. In the second experiment, co-treatment with GT in the drinking water from 1 week before 300 or 600 ppm PCP treatment in the diet to the end of the experiment at week 3 in B6C3F1 male mice suppressed increases of serum ALT activities, 8-oxodeoxyguanosine (8-oxodG) levels in liver DNA and bromodeoxyuridine (BrdU) labeling indices (LIs) of hepatocytes and intrahepatic biliary epithelial cells induced by PCP. These findings suggest that regular intake of green tea may reduce the carcinogenic risk posed by an environmental pollutant, PCP, presumably due to effects on oxidative stress.
Prevention of dual promoting effects of pentachlorophenol, an environmental pollutant, on diethylnitrosamine-induced hepato- and cholangio-carcinogenesis in mice by green tea infusion
2 Faculty of Living Sciences, Showa Women's University, 1-7, Taishido, Setagaya-ku, Tokyo 154-8571, Japan
3 Division of Medical Safety Science, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501
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