Alan J. Townsend

Professor of Biochemistry
B.S., University of South Florida, 1974
Ph.D. (Pharmacology), University of North Carolina, Chapel Hill, 1986
Telephone: (336) 713-7215
E-mail: atown@wfubmc.edu

The process of natural selection has resulted in the evolution of a diverse array of defensive mechanisms that organisms can utilize to survive in a toxic environment. These include changes in the cellular accumulation or metabolism of toxic agents, or alterations in the structure or quantity of sensitive cellular target macromolecules. The research in my laboratory is aimed at defining the role of specific gene products (proteins) in determining the sensitivity of normal and tumor cells to mutagenic or cytotoxic agents, including both cancer chemotherapeutic drugs and environmental carcinogens. One current focus of my research is on enzymes of the glutathione S-transferase (GST) gene family, some of which can catalyze the detoxification of a broad spectrum of reactive electrophiles by conjugation with the sulfhydryl-containing tripeptide glutathione (GSH). The approach employed in this project is to transfer individual genes of interest, in this case one of several different GST isoenzymes, into cell lines which normally express little or none of the particular protein encoded by that gene. Stably transfected cell lines, which should be genetically identical except for overexpression of the transfected gene, can then be tested directly in comparison with the non-expressing parent cell line to see if increased expression of that gene confers any protective advantage against selected anticancer drugs, toxins or mutagens. A second project concerns the role of aldehyde dehydrogenases in resistance to damage by toxic aldehydes, particularly lipid aldehydes formed as a result of lipid peroxidation during oxidant stress. A similar transgenic modeling approach is employed in this project. A third project under development aims to understand the mechanism whereby production of prostaglandins by cyclooxygenase enzymes can induce programmed cell death under certain conditions, and thus may contribute to toxicity that results from oxidative stress.

The ultimate objective of this research is to identify and characterize cellular defense mechanisms which may be manipulated pharmacologically to therapeutic advantage, for chemoprevention or chemotherapy of cancer. Trainees in my laboratory may acquire expertise in enzyme kinetics, protein purification, analytical methods for proteins and nucleic acids, recombinant DNA techniques, gene cloning and transfer technology, drug metabolism, and cell culture.

Recent publications:

Kushman ME, Kabler SL, Fleming MH, Morrow CS, and Townsend AJ.  Expression of hGSTP1 confers resistance to benzo[a]pyrene mutagenesis in stably transfected V79MZ cells co-expressing hCYP1A1. Carcinogenesis 28: 207-214, 2006. 
 http://carcin.oxfordjournals.org/cgi/content/abstract/28/1/207

Kushman, Mary E., Kabler , Sandra L., Ahmad, Sarfaraz, Doehmer, Johannes, Morrow, Charlie S., and Townsend, Alan J.   .Protective efficacy of hGSTM1-1 against B[a]P and (+)- or (-)-B[a]P-7,8-dihydrodiol cytotoxicity, mutagenicity, and macromolecular adducts in V79 cells co-expressing hCYP1A.   Toxicological Sciences 99: 51-57, 2007;

http://toxsci.oxfordjournals.org/cgi/reprint/kfm133?ijkey=heZzE3WDgf6GX3i&keytype=ref

Kushman, Mary E., Kabler , Sandra L., Ahmad, Sarfaraz, Doehmer, Johannes,

Morrow, Charles S., and Townsend, Alan J.   Cytotoxicity and mutagenicity of

dibenzo[a,l]pyrene and (±)-dibenzo[a,l]pyrene-11,12-dihydrodiol in V79MZ cells co-expressing either hCYP1A1 or hCYP1B1 and human glutathione S-transferase A1-1. Mutat. Res.: Fund. Mol. Mech. Mutagen. 624: 80-87, 2007.

http://dx.doi.org/10.1016/j.mrfmmm.2007.04.004

Morrow, C. S., C. Peklak-Scott, B. Bishwokarma, T. E. Kute, P. K. Smitherman, A. J. Townsend. Multidrug resistance protien 1 (MRP1, ABCC1) mediates resistance to mitoxantrone via glutathione-dependent drug efflux. Mol. Pharmacol. 69:1499-1505, 2006.

Xu, Mian, Moore, Joseph E., Leone-Kabler, Sandra, McCoy, Thomas P., Swank, Adam, Nelson, Garret B., Ross, Jeffrey A., Townsend, Alan J. and Miller, Mark Steven. Expression of Glutathione S-Transferases in Fetal Lung and Liver Tissue from Parental Strains and F1 Crosses between C57BL/6 and BALB/c F1 Mice Following in utero Exposure to 3-Methylcholanthrene. Biochem Pharmacol 72: 115-123, 2006.

Hu, Yunping, Tennant, Alan H., Kabler, Sandra, Townsend, Alan J., and Kligerman, Andrew D. The Induction of DNA-Protein Crosslinks in V79 cell lines Transfected with the Murine Glutathione-S-Transferase Theta 1 Gene by the Metabolism of Dichloromethane to Formaldehyde. Mutation Research 607: 231-239, 2006.

Kushman ME, Kabler SL, Fleming MH, Morrow CS, and Townsend AJ. Expression of hGSTP1 confers resistance to benzo[a]pyrene mutagenesis in stably transfected V79MZ cells co-expressing hCYP1A1. Carcinogenesis 28: 207-214, 2006.

Riddick, D. S., C. Lee, S. Ramji, E. C. Chinje, R. L. Cowen,K. J. Williams, A. V. Patterson, I. J. Stratford, C. S. Morrow, A. J. Townsend, Y. Jounaidi, C. Chen, T. Su, H. Lu, P. S. Schwartz, and D. J. Waxman. Cancer chemotherapy and drug metabolism. Drug Metab. Dispos. 33:1083-96, 2005.

Peklak-Scott, C., Townsend A. J., Morrow, C. S. Dynamics of glutathione conjugation and conjugate efflux in detoxification of the carcinogen, 4-nitroquinoline 1-oxide: contributions of glutathione, glutathione S-transferase, and MRP1. Biochemistry 44:4426-4433, 2005.

Smitherman, P. K., Townsend, A. J., Kute, T. E., Morrow, C. S. Role of multidrug resistance protein 2 (MRP2, ABCC2) in alkylating agent detoxification: MRP2 potentiates glutathione S-transferase A1-1-mediated resistance to chlorambucil cytotoxicity. J. Pharmacol. Exp. Ther. 308:260-267, 2004.

Paumi, C. M., Smitherman, P. K., Townsend, A. J., Morrow, C. S. Glutathione S-transferases (GSTs) inhibit transcriptional activation by the peroxisomal proliferator-activated receptor gamma (PPAR gamma) ligand, 15-deoxy-delta 12,14prostaglandin J2 (15-d-PGJ2). Biochemistry 43: 2345-2352, 2004.

Pietsch, E. C., Welker, M. E., Leone-Kabler, S., Townsend, A. J., Torti, F. M., and Torti, S. V. Oxathiolene oxides: a novel family of compounds that induce ferritin, glutathione-S-transferase, and other proteins of the phase II response. Biochemical Pharmacology, 65: 1261-1269, 2003.

Pappa, A., Chen, C., Koutalos, Y., Townsend, A. J. and Vasiliou, V. ALDH3A1 protects human corneal epithelial cells from ultraviolet- and 4-hydroxy-2-nonenal-induced oxidative damage. Free Rad. Biol. Med. 34: 1178-1189, 2003.

Paumi, C. M., Wright, M., Townsend, A. J. and Morrow, C. S. Multidrug resistance protein (MRP) 1 and MRP3 attenuate cytotoxic and transactivating effects of the cyclopentenone prostaglandin 15-deoxy-δ12,14 prostaglandin J2 in MCF7 breast cancer cells. Biochemistry 42:5429-5437, 2003.

Figure1. Overexpression of human GSTP-1 by transfection in T47D breast carcinoma cells results in protection against DNA damage and cytotoxicity. A) Covalent attachment of Benzo[a]pyrene diol-epoxide (BPDE) to cellular nucleic acids (DNA + RNA) is reduced in T47D. Cells (closed symbols); B)Lethality of Benzo[a]pyrene is also decreased in T47D cells.