PLACENTAL GLUTATHIONE-S-TRANSFERASE ISOENZYME EXPRESSION IN POLYCYCLIC AROMATIC HYDROCARBON-INDUCED HAMSTER BUCCAL POUCH MUCOSA

Placental glutathione S-transferase (GST-P) immunohistochemical activi ty in polycyclic aromatic hydrocarbon (PAH)-induced hamster buccal pou ch mucosa (HBPM) was investigated. Equimolar concentrations of 3,4-ben zo[a]pyrene (BP), benz[a]anthracene (BA) and 20-methylcholanthrene (MC ) in mineral oil solution were applied three times per week for up to 20 weeks to bilateral pouches of the hamsters. Control pouches were tr eated with 7,12-dimethylbenz[a]anthracene (DMBA), turpentine and miner al oil, respectively. A significant increase in the number of GST-P fo ci in the dysplastic pouches was found when compared with the hyperker atotic and hyperplastic pouches after 5 weeks' DMBA treatment. The ave rage numbers of GST-P positive stainings were significantly higher in DMBA-treated groups than in BP-, BA- and MC-treated groups killed at 5 , 20, 30 and 40 weeks. No GST-P positivity was found in any pouches tr eated with turpentine and mineral oil observed at various periods. The se results highlight the carcinogen-specificity of GST-P chemically in duced in HBPM and indicate that induction of GST-P in pouch mucosa is linked with the carcinogenic potency of PAHs. The present study underp ins the hypothesis that GST-P chemically induced in HBPM is an early m arker of ongoing squamous cell carcinogenesis. (C) 1998 Elsevier Scien ce Ltd. All rights reserved.