Expression of microsomal and cytosolic epoxide hydrolases in cultured rat hepatocytes and hepatoma cell lines.
Microsomal epoxide hydrolase activity, determined using benzpyrene 4,5-oxide and styrene 7,8-oxide, increased in cultured hepatocytes compared to freshly isolated cells. In contrast, cytosolic epoxide hydrolase activity, assayed using trans-stilbene oxide, had decreased 80% by 24 hr and was barely detectable after 96 hr in culture. There was no difference in enzyme activity between freshly isolated hepatocytes and the two rat hepatoma cell lines McA-RH 7777 and H4-II-E, when styrene 7,8-oxide was used as substrate. However, benzpyrene 4,5-oxide hydrolase activity of the McA-RH 7777 and H4-II-E cell lines were 55 and 10%, respectively, of freshly isolated hepatocytes. These results show that hepatoma cell lines provide a suitable system for studying the regulation of both the microsomal and cytosolic epoxide hydrolase enzymes.
D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004851:Epoxide Hydrolases / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism; D008114:Liver Neoplasms, Experimental / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D001580:Benzopyrenes; D004852:Epoxy Compounds; C006707:benzo(a)pyrene 4,5-epoxide; C013690:styrene oxide; D004851:Epoxide Hydrolases