Reserach Interest
The uptake, metabolic activation or inactivation, and elimination of drugs, carcinogens, and environmental toxicants are tightly controlled processes that significantly impact the biological activity of these compounds, including any pathological response. Research in our laboratory is focused on molecular mechanisms controlling the expression of drug and toxicant metabolizing enzymes, including chemical-induced changes in gene expression, genetic variability, and temporal- and tissue-specific control mechanisms. Studies currently being conducted emphasize two major enzymes systems, the cytochrome P450 and flavin-containing monooxygenase gene families.
Cytochrome P450: Although several enzyme systems are known to participate in the metabolic transformation of xenobiotics, the cytochrome P450-dependent monooxygenases are widely recognized as playing a dominant role. The cytochromes P450 are products of a super gene family with 57 distinct members in the human. Of these many gene products, the CYP2C9 enzyme accounts for between 15 and 20% of total hepatic cytochrome P450 and has a major role in the metabolic disposition of approximately 20% of clinically relevant drugs. Studies are being conducted to fully characterize genetic variants within the CYP2C9 promoter in different populations and determine their impact on gene function. These studies will lead to a better understanding of mechanisms controlling CYP2C9 expression as well as the contribution of CYP2C9 genetic variation to inter-individual differences in drug response.
Within the human CYP3A family, major changes in hepatic expression are observed during development. Thus, CYP3A7 is the dominant form in the fetus while CYP3A4, if present, is expressed at low levels. Within the first one to two years after birth, CYP3A7 expression is extinguished in most individuals and CYP3A4 expression increases to be the dominant enzyme in the adult liver. Studies are underway to identify and characterize the molecular mechanisms controlling this developmental transition.
Flavin-containing Monooxygenase: Although the cytochrome P450-dependent monooxygenases are perhaps the most important system in the metabolic transformation of xenobiotics, there is increasing awareness of the flavin-containing monooxygenase (FMO) system and its contribution to this process. These enzymes efficiently catalyze the monooxygenation of a variety of nucleophilic nitrogen, sulfur, selenium, and phosphorous containing xenobiotics to their respective oxides.
This enzyme system is encoded by a family of five genes (FMO1-5) sharing between 50 and 60% amino acid sequence identity. Each FMO gene product exhibits unique properties, however, due to the nature of the FMO catalytic mechanism, substrate specificity is broad and overlapping. Significant polymorphisms and/or allelic variations have been documented in animal models and humans. We have demonstrated a developmental transition in the expression of the two major FMO hepatic enzymes in the human, FMO1 and FMO3, with FMO1 only be expressed in the fetus while FMO3 is only expressed in the adult. Current studies are focused on identifying mechanisms controlling FMO1 and FMO3 expression, as well as identifying common genetic variants that will help explain interindividual differences in FMO expression and their contribution to drug and toxicant response.
Recent Publications
Krueger, S.K., Siddens, L.K., Henderson, M.D., Andreason, E.A., Tanguay, R.L., Pereria, C.B., Cabacungan, E.T., Hines, R.N., Ardlie, K. and Williams, D.E. Haplotype and functional analysis of four flavin-containing monooxygenase isoform 2 (FMO2) polymorphisms in Hispanics. Pharmacogenetics 15:245256, 2005.
Koukouritaki, S.B., Poch, M.T., Cabacungan, E.T., McCarver, D.G. and Hines, R.N. Discovery of Novel Flavin-Containing Monooxygenase 3 (FMO3) Single Nucleotide Polymorphisms and Functional Analysis of Upstream Haplotype Variants. Mol. Pharmacol. 68:383-392, 2005.
Wan, J., Carr, B.A., Shane Cutler, N., Lanza, D.L., Hines, R.N. and Yost, G.S. Sp1 and Sp3 regulate basal transcription of the human CYP2F1 gene. Drug Metab. Disp. 33:1244-1253, 2005.
Poch, M.T., Cutler, N.S., Yost, G.S. and Hines, R.N. Identification of multiple mechanisms involved in human CYP4B1 tissue-selective expression. Drug Metab. Disp. 33:1174-1184, 2005.
Koukouritaki, S.B. and Hines, R.N. Flavin-Containing Monooxygenase (FMO) Genetic Polymorphism: Impact on Chemical Metabolism and Drug Development. Pharmacogenomics 6:807-822, 2005.
Nong, A., McCarver, D.G., Hines, R.N. and Krishnan, K. Modeling of interchild differences in pharmacokinetics on the basis of subject-specific data on physiology and hepatic CYP2E1 levels: a case study with toluene. Toxicol. Appl. Pharmacol. 214:78-87, 2006.
Duanmu, Z., Weckle, A., Koukouritaki, S.B., Hines, R.N., Falany, C.N., Kocarek, T.A. and Runge-Morris, M. Developmental expression of aryl, estrogen and hydroxysteroid sulfotransferases in pre- and postnatal human liver. J. Pharmacol. Exptl. Ther. 316:1310-1317, 2006.
Hines, R.N. Developmental and Tissue-Specific Expression of Flavin-Containing Monooxygenase 1 and 3. Expert Opinion Drug Metabol Toxicol 2:41-49, 2006.
Krueger, S.K., VanDyke, J.E., Hines, R.N. and Williams, D.E. The role of flavin-containing monooxygenase (FMO) in the metabolism of tamoxifen and other tertiary amines. Drug Metab. Revs. 38:139-147, 2006.
Cooper, R.L., Lamb, J.C., Barlow, S. M., Bentley, K., Brady, A. M., Doerrer, N.G., Eisenbrandt, D.L., Fenner-Crisp, P.A., Hines, R.N., Irvine, L.F.H., Kimmel, C.A., Koeter, H., Li, A.A., Makris, S.L., Sheets, L.P., Speijers, G.J.A. and Whitby, K.E. A tiered approach to life stage testing for agricultural chemical safety assessment. Crit. Revs. Toxicol. 36:69-98, 2006.
Hines, R.N. and McCarver, D.G. Pharmacogenomics and the Future of Drug Therapy. Pediatric Clinics of North America: Scientific Foundations of Clinical Practice Part I (Kliegman, R.M. and Avner, E.D., eds.), pp. 591-619, W.B. Saunders Co., Philadelphia, PA, 2006.
Yang, F., Tong, X., McCarver, D.G., Hines, R.N. and Beard, D.A. Population-based analysis of methadone distribution and metabolism using an age-dependent physiologically based pharmacokinetic model. J. Pharmokinet. Pharmacodyn. 33:485-518, 2006.
Vyas, P.M., Roychowdhury, S., Khan, F.D., Prisinzano, T.E., Lamba, J., Schuetz, E.G., Blaisdell, J., Goldstein, J.A., Munson, K.L., Hines, R.N., Svensson, C.K., Enzyme- mediated protein haptenation of dapsone and sulfamethoxazole in human keratinocytes - 1. Expression and role of cytochromes P450. J. Pharmacol. Exptl. Ther. 319:488-496, 2006.
Vyas, P.M., Roychowdhury, S., Koukouritaki, S.B., Hines, R.N., Krueger, S.K., Williams, D.E., Nauseef, W.M., Svensson, C.K., Enzyme-mediated protein haptenation of dapsone and sulfamethoxazole in human keratinocytes - 2. Expression and role of flavin-containing monooxygenases and peroxidases. J. Pharmacol. Exptl. Ther. 319:497-505, 2006.
Zaya, M.J., Hines, R.N. and Stevens, J.C. Epirubicin glucuronidation and UGT2B7 developmental expression. Drug Metab. Disp. 34:2097-2101, 2006.
Koukouritaki, S.B., Poch, M.T., Henderson, M.C., Siddens, L.K., Krueger, S.B., VanDyke, J.E., Williams, D.E., Pajewski, N.M., Wang, T. and Hines, R.N. Identification and functional analysis of human flavin-containing monooxygenase 3 (FMO3) genetic variants. J . Pharmacol. Exptl. Ther. 320:266-273, 2007.
Shadley JD, Divakaran K, Munson K, Hines RN, Douglas K and McCarver DG. Identification and functional analysis of a CYP2E1 far upstream enhancer. Mol Pharmacol 71(6):1630-1639, 2007.
Klick DE and Hines RN. Mechanisms Regulating Human FMO3 Transcription. Drug Metab Revs 39:419-442, 2007.
Hines, R.N. Ontogeny of Human Hepatic Cytochromes P450. J. Biochem. Mol. Toxicol.21(4):169-175, 2007.
Hines RN, Koukouritaki SB, Poch MT and Stephens MC. Regulatory polymorphisms and their contribution to interindividual differences in the expression of enzymes influencing drug and toxicant disposition. Drug Metab. Revs., in press.
Hines RN. The ontogeny of drug metabolism enzymes and implications for adverse drug events. Pharmacol. Therapeut., doi: 10.1016/j.pharmthera.2008.02.005.
Hines RN. Ontogeny of drug metabolizing enzymes/pediatric exclusivity. In: Handbook of drug metabolism (Pearson, P.G. and Wienkers, L.C., eds.), in press, Informa Healthcare, New York, NY, 2008.
Kramer MA, Rettie AE, Rieder MJ, Cabacungan ET and Hines RN. Novel CYP2C9 promoter variants and assessment of their impact on gene expression. Mol Pharmacol doi: 10.1124/mol.107.044149.