Development of monoclonal antibodies to human microsomal epoxide hydrolase and analysis of “preneoplastic antigen”-like molecules

Abstract

Microsomal epoxide hydrolase (mEH) is a drug metabolizing enzyme which resides on the endoplasmic reticulum (ER) membrane and catalyzes the hydration of reactive epoxide intermediates that are formed by cytochrome P450s. mEH is also thought to have a role in bile acid transport on the plasma membrane of hepatocytes. It is speculated that efficient execution of such multiple functions is secured by its orientation and association with cytochrome P450 enzymes on the ER membrane and formation of a multiple transport system on the plasma membrane. In certain disease status, mEH loses its association with membrane and can be detected as distinct antigens in the cytosol of preneoplastic foci of liver (preneoplastic antigen), in the serum in association with hepatitis C virus infection (AN antigen), or in some brain tumors. To analyze the antigenic structures of mEH in physiological and pathological conditions, we developed monoclonal antibodies against different portions of mEH. Five different kinds of antibodies were obtained: three, anti-N-terminal portions; one, anti-C-terminal; one, anti-conformational epitope. By combining these antibodies, we developed antigen detection methods which are specific to either the membrane-bound form or the linearized form of mEH. These methods detected mEH in the culture medium released from a hepatocellular carcinoma cell line and a glioblastoma cell line, which was found to be a multimolecular complex with a unique antigenic structure different from that of the membrane-bound form of mEH. These antibodies and antigen detection methods may be useful to study pathological changes of mEH in various human diseases.

The Association between mrna Expression Levels of Ephx1 and Prognosis of Acute Myeloid Leukemia

“…The product of EPHX1 gene, mEH, is a drug metabolizing enzyme found on the endoplasmic reticulum of many tissues and is responsible for catalyzing the hydration of reactive epoxide intermediates that are formed bycytochrome P450s, including PAHs [10,13]. The results shown mEH protein was high expression in persistence non-remission patients compared to control group.…”

Monoclonal antibodies reveal multiple forms of expression of human microsomal epoxide hydrolase

“…Table 1 shows the monoclonal antibodies to human mEH developed in the previous study and grouped into five groups depending on their epitope selectivities (Duan et al , 2012). Using five antibodies, one from each type (type I: 5D8; type II: K4F8; type III: K2B7; type IV: 6E3; type V: 2G2), we examined the expression of mEH epitopes in various human cells by flow cytometry.…”

“…In the previous study, we have shown that the HCC line Huh-1 and the glioblastoma cell line LN-71 release mEH into the culture medium whereas other cell lines did not (Duan et al , 2012). It reminded us preneoplastic antigen (PNA) which had been described as an antigen in preneoplastic foci in livers that is released into the blood (Okita and Farber, 1975), and later found to be immunologically identical to mEH (Levin et al , 1978).…”

“…THLE-5b, Huh-7, Huh-1, M1, U87MG, LN-Z308, and LN-71 have been described (Duan et al , 2012). LN-18, Raji, and Jurkat were obtained from the American Type Culture Collection (ATCC; Manassas, VA).…”

“…In the previous study, we have developled several anti-mEH monoclonal antibodies which chould be grouped into the five types depending on their epitope selectivities (Duan et al , 2012). They were comprised of antibodies agaist N-terminal, C-terminal, and conformational epitopes.…”