Monoclonal Antibodies to Cytochrome P450

Our Laboratory has developed a library of monoclonal antibodies to study cytochrome P450 metabolism of carcinogens and drugs.

The cytochrome P450 enzymes collectively metabolize xenobiotics which include almost all drugs, carcinogens, and environmentally relevant small molecules and activate chemicals to their mutagenic or carcinogenic forms. They also metabolize certain classes of endogenous compounds such as steroids, fatty acids and prostaglandins. Thus, studies of the cytochrome P450 enzyme complex are important for the understanding of differences in human sensitivity to drugs, carcinogens, environmental chemicals and the regulation of certain endogenous metabolism.

The monoclonal antibodies are used to determine the amount of an individual cytochrome P450 protein in a tissue and its contribution to the total metabolism of a substrate in a tissue containing multiple cytochrome P450s. These results have implications for studies in drug efficacy, toxicity and human polymorphisms. The monoclonal antibodies are unique and exquisitely precise probes for determining the amount and role of a single cytochrome P450. Our intention is to increase the number of monoclonal antibodies in our library so that all of the major human cytochrome P450s can be assayed.

Human P450	MAb	Ig Subtype	ELISA	Immunoblot	Inhibition %	Example Substrate	Ref
1A1	1-7-1	Ig G1	+	-	>90	7-EC, Phenanthrene, B[a]P	1, 2
	1-599-16	Ig G1	+	+	-
1A2	26-7-5	Ig G1	+	+	>90	7-EC, Phenanthrene, B[a]P	2
2A6	151-45-4	Ig G1	+	+	>90	Coumarin, Phenanthrene, 4-Nitrophenol, 7-EC.	3
2B6	49-10-20	Ig G2b	+	+	>90	Diazepam, Testosterone, 7-EC, Phenanthrene,	4
2C8/9/18/19	1-68-11	Ig M	+	-	>85-90	Diazepam, Phenanthrene	5, 6
2D6	512-1-8	Ig G1	+	+	>90	Bufuralol, Imipramine Dextromethorphen,	6, 7
	50-1-3	Ig G1	+	-	>90	Bufuralol, Imipramine Dextromethorphen,	6, 7
2E1	1-73-18	Ig M	+	-	>90	Phenanthrene, Toluene, p-Nitroanisole, Chlorzoxazone, 4-Methylanisole	8
	2-106-12	Ig G1	+	+	-		8
3A4/5	3-29-9	Ig M	+	-	>90	Diazepam, testosterone, Taxol, Cyclosporin, Phenanthrene	9
	275-1-2	Ig M	+	+	-		9

Abbreviations: MAb, monoclonal antibody; 7-EC, 7-ethoxycoumarin; B[a]P, Benzo[a]pyrene
Note: All MAbs are specific to target P450 and do not interact with 11 other human P450s.

1. S.S. Park, T. Fujino, D. West, F.P. Guengerich and H.V. Gelboin: Monoclonal antibodies that inhibit enzyme activity of 3-methylcholanthrene-induced cytochrome P-450. Cancer Res 42, 1798-808 (1982).

2. T.J. Yang, Y. Sai, K.W. Krausz, F.J. Gonzalez and H.V. Gelboin: Specific inhibitory monoclonal antibodies to human cytochrome P450 1A2: analysis of phenacetin O-deethylation in human liver. Pharmacogenetics , 8:375-382 (1998).

3. Y. Sai, T.J. Yang, K.W. Krausz, F.J. Gonzalez and H.V. Gelboin: Inhibitory monoclonal antibodies to cytochrome P450 2A6. Pharmacogenetics , in press (1998).

4. T.J. Yang , K.W. Krausz, M. Shou, S.K. Yang, B.J.T. M., F.J. Gonzalez and H.V. Gelboin: An inhibitory monoclonal antibody to human cytochrome P450 2B6. Biochem. Pharmacol. 55, 1633-1640 (1998).

5. S.S. Park, D.J. Waxman, D.P. Lapenson, J.B. Schenkman and H.V. Gelboin: Monoclonal antibodies to rat liver cytochrome P-450 2c/RLM5 that regiospecifically inhibit steroid metabolism. Biochem Pharmacol 38, 3067-74 (1989).

6. H.V. Gelboin, K.W. Krausz, M. Shou, F.J. Gonzalez and T.J. Yang: Inhibitiory monoclonal antibodies define the role of cytochrome P450 in human tissue: polymorphically expressed P450 2D6 as paradigm. Pharmacogenetics 7, 467-477 (1997).

7. K.W. Krausz, T.J. Yang, F.J. Gonzalez, M. Shou and H.V. Gelboin: Inhibitory monoclonal antibodies to human cytochrome P450 2D6. Biochem Pharmacol 54, 15-17 (1997).

8. H.V. Gelboin, I. Goldfarb, K.W. Krausz, J. Grogan, K.R. Korzekwa, F.J. Gonzalez and M. Shou: Inhibitory and noninhibitory monoclonal antibodies to human cytochrome P450 2E1. Chem Res Toxicol 9, 1023-30 (1996).

9. H.V. Gelboin, K.W. Krausz, I. Goldfarb, J.T. Buters, S.K. Yang, F.J. Gonzalez, K.R. Korzekwa and M. Shou: Inhibitory and non-inhibitory monoclonal antibodies to human cytochrome P450 3A3/4. Biochem Pharmacol 50, 1841-50 (1995).

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