Stephen S. Hecht

Education:

B.S., Duke University, 1964
Ph.D., Massachusetts Institute of Technology, 1968

The goal of research in the Hecht laboratory is to understand the mechanisms by which carcinogens are metabolically activated and detoxified in humans, and use this knowledge to develop practical strategies for cancer prevention. This group studies the metabolism of carcinogens that are present in tobacco products, the human diet and the general environment; particular focus is on nitrosamines, aldehydes and polycyclic aromatic hydrocarbons. Studies in laboratory animals are used to understand metabolic pathways. Then methods are developed to quantify metabolism of these carcinogens in humans, typically by employing GC-MS, LC-MS, or related methods to analyze carcinogen metabolites in urine, or carcinogen DNA or protein adducts in tissue or blood. These methods are applied in molecular epidemiology studies designed to determine factors that influence susceptibility to cancer development in exposed humans. Naturally occurring compounds that can prevent the metabolic activation of carcinogens or enhance their detoxification are also investigated. Mechanisms by which these chemopreventive agents act are determined in laboratory animals, then investigated in humans to investigate potential efficacy in cancer prevention.

Specific current project areas include the following:

Metabolism and DNA binding of tobacco-specific nitrosamines
Tobacco-specific nitrosamines are a group of carcinogens derived from tobacco alkaloids by nitrosation. These compounds, which include 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N'-nitrosoanabasine (NAB), and N'-nitrosoanatabine (NAT) are widely regarded as important causative agents for cancer in people who use tobacco products. We have focused on mechanisms by which NNK and NNN cause cancer in laboratory animals. Metabolic pathways of these compounds have been elaborated and structures of resulting DNA adducts determined. Our current goals are to carry out a comprehensive analysis of NNK- and NNN-DNA adducts in vitro, in tissues of laboratory animals, and in humans, using LC-MS; to investigate the balance of NNK metabolic activation vs. detoxification in humans, using stable isotope approaches; to investigate the endogenous formation of NNK in people who use tobacco products; and to investigate new methods for long term biomonitoring of human tobacco-specific nitrosamine uptake.

Suggested reading:

Hecht, S.S. Biochemistry, biology, and carcinogenicity of tobacco-specific N-nitrosamines. Chem. Res. Toxicol., 11: 559-603, 1998. PubMed citation

Sturla, S.J, Scott, J., Lao, Y., Hecht, S.S. and Villalta, P.W.  Mass spectrometric analysis of relative levels of pyridyloxobutylation Adducts Formed in the Reaction of DNA with a chemically activated form of the tabacco-specific carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone.  Chem. Res. Toxicol., 18: 1048-1055, 2005.  PubMed citation

Lao, Y., Yu, N., Kassie, F., Villalta, P.W., and Hecht, S.S. Analysis of pyridyloxobutyl DNA adducts in F344 rats chronically treated with (R)- and (S)-N'-nitrosonornicotine. Chem. Res. Toxicol., 20: 246-256, 2006.  PubMed citation

Lao, Y., Yu, N., Kassie, F., Villalta, P.W., and Hecht, S.S. Formation and accumulation of pyridyloxobutyl DNA adducts in F344 rats chronically treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and enantiomers of its metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol. Chem. Res. Toxicol., 20: 235-245, 2006.  PubMed citation

Hecht, S.S., Han, S., Kenney, P.M.J., Wang, M., Lindgren, B., Wang, Y., Lao, Y., Hochalter, J.B., and Upadhyaya, P. Investigation of the reaction of myosmine with sodium nitrite in vitro and in rats. Chem. Res. Toxicol., 20: 543-549, 2007.  PubMed citation

Wang, M., Cheng, G., Villalta, P.W., and Hecht, S.S. Development of liquid chromatography electrospray ionization tandem mass spectrometry methods for analysis of DNA adducts of formaldehyde and their application to rats treated with N-nitrosodimethylamine or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Chem. Res. Toxicol., 20: 1141-1148, 2007.  PubMed citation

Cheng, G., Wang, M., Upadhyaya, P., Villalta, P.W., and Hecht, S.S. Formation of formaldehyde adducts in the reactions of DNA and deoxyribonucleosides with α-acetates of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and N-nitrosodimethylamine (NDMA). Chem. Res. Toxicol., epub ahead of print Jan 19, 2008.  PubMed citation

Hecht, S.S. Progress and challenges in selected areas of tobacco carcinogenesis. Chem. Res. Toxicol., 21: 160-171, 2008.  PubMed citation

 

Biomonitoring of human uptake and metabolism of tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons (PAH)
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-Glucs) are quantitatively significant urinary metabolites of NNK in humans. Measurement of these metabolites, by GC with nitrosamine selective detection, GC-MS, or LC-MS provides a useful way of monitoring NNK uptake in smokers, smokeless tobacco users, and non-smokers exposed to secondhand tobacco smoke. 1-Hydroxypyrene (1-HOP) is a metabolite of pyrene and a good indicator of carcinogenic PAH uptake in humans. We have developed improved methods for quantitation of NNAL and 1-HOP in human urine and are applying these methods in a variety of collaborative studies examining various topics including: effects of reduced smoking on uptake of NNK and PAH, uptake of NNK and PAH in people who use tobacco products purported to be less harmful, uptake of carcinogens by non-smokers exposed to secondhand cigarette smoke, ethnic differences in carcinogen uptake and metabolism, and the relationship of carcinogen uptake to lung and pancreatic cancer.

Suggested reading:

Hecht, S.S. Human urinary carcinogen metabolites: biomarkers for investigating tobacco and cancer. Carcinogenesis, 23: 907-922, 2002. PubMed citation

Hecht, S.S. Tobacco carcinogens, their biomarkers and tobacco-induced cancer. Nature Rev. Cancer, 3: 733-744, 2003.  PubMed citation

Hecht, S.S., Murphy, S.E., Carmella, S.G., Li, S., Jensen, J., Le, C., Joseph, A.M. and Hatsukami, D.K. Similar Uptake of lung carcinogens by smokers of regular, light, and ultralight cigarettes. Cancer Epidemiology, Biomarkers & Prev., 14: 693-698, 2005. PubMed citation

Hecht, S.S., Carmella, S.G., Le, K., Murphy, S.E., Boettcher, A.J., Le, C., Koopmeiners, J., An, L., and Hennrikus, D.J. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides in the urine of infants exposed to environmental tobacco smoke. Cancer Epidemiol. Biomarkers & Prev., 15: 988-992, 2006.  PubMed citation

Stepanov, I., Hecht, S.S., Lindgren, B., Jacob, P., Wilson, M., and Benowitz, N. Relationship of human toenail nicotine, cotinine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol to levels of these biomarkers in plasma and urine. Cancer Epidemiol, Biomarkers, & Prev., 16: 1382-1386, 2007.  PubMed citation

Hecht, S.S., Carmella, S.G., Murphy, S.E., Riley, W.T., Le, C., Luo, X., Mooney, M., and Hatsukami, D.K. Similar exposure to a tobacco-specific carcinogen in smokeless tobacco users and cigarette smokers. Cancer Epidemiol, Biomarkers, & Prev., 16: 1567-1572, 2007.  PubMed citation

Hecht, S.S., Carmella, S.G., Edmonds, A., Murphy, S.E., Stepanov, I., Luo, X., and Hatsukami, D.K. Exposure to nicotine and a tobacco-specific carcinogen increase with duration of use of smokeless tobacco. Tobacco Control, in press, 2007.

Stepanov, I. and Hecht, S.S. Detection and quantitation of N'-nitrosonornicotine in human toenails by liquid chromatography-electrospray ionization-tandem mass spectrometry. Cancer Epidemiol, Biomarkers, & Prev.,in press, 2008.

Hecht, S.S., Carmella, S.G., Stepanov, I., Jensen, J., Anderson, A., and Hatsukami, D. Metabolism of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone to its biomarker total NNAL in smokeless tobacco users. Cancer Epidemiol, Biomarkers, & Prev., in press, 2008.

 

Metabolism and DNA binding of carcinogenic cyclic nitrosamines
Carcinogenic cyclic nitrosamines such as N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP) are found in the diet and in tobacco smoke, and are probably formed endogenously in humans by nitrosation of the corresponding cyclic amines. NPYR and NPIP, while structurally related, have remarkably different carcinogenic activities in rats. NPYR is a liver carcinogen which never induces tumors of the esophagus while NPIP causes esophageal and liver tumors. We have determined that the likely reason for this difference is selective metabolic alpha-hydroxylation of NPIP by cytochrome P450 enzymes in the rat esophagus, a reaction that is barely observable for NPYR. THe chemistry of DNA adduct formation by NPYR has been extensively investigated in our laboratory. Current directions are focused on the identification and quantitation of NPYR-DNA adducts in human tissues, using LC-MS techniques.

Suggested reading:

Wong, H.L., Murphy S.E. and Hecht, S.S. Cytochrome P450 2A-catalyzed metabolic activation of structurally similar carcinogenic nitrosamines: N'-nitrosonornicotine enantiomers, N-nitrosopiperidine, and N-nitrosopyrrolidine.  Chem. Res. Toxicol.,18: 61-69, 2005. PubMed citation

Wang, M., Lao, Y., Cheng, G., Shi, Y., Villalta, P.W., and Hecht, S.S. Identification of adducts formed in the reaction of α-acetoxy-N-nitrosopyrrolidine with deoxyribonucleosides and DNA. Chem. Res. Toxicol., 20: 625-633, 2007.  PubMed citation

Wang, M., Lao, Y., Cheng, G., Shi, Y., Villalta, P.W., Nishikawa, A. and Hecht, S.S. Analysis of adducts in hepatic DNA of rats treated with N-nitrosopyrrolidine. Chem. Res. Toxicol., 20: 634-640, 2007.  PubMed citation

 

DNA adducts of carcinogenic aldehydes
Acrolein and crotonaldehyde are lipid peroxidation products and toxicants. Both are found in relatively high levels in cigarette smoke as well as the general environment. Both form 1,N² -propano-dG DNA adducts. Acrolein has been shown to modify the p53 tumor suppressor gene in ways similar to the mutational pattern found in lung cancer from smokers. We have developed sensitive LC-MS methods to quantify DNA adducts of acrolein and crotonaldehyde in human tissues and are applying these in studies designed to evaluate the role of smoking in their formation. Acetaldehyde is a major metabolite of ethanol and is found in mg per cigarette quantities in smoke. Acetaldehyde is believed to play a role in ethanol induced carcinogenesis. We have developed methods to analyze acetaldehyde DNA adducts such as 1,N² -ethylidene-dG in human tissues and are applying these in studies to evaluate their role in carcinogenesis.

Suggested reading:

Wang, M., McIntee, E.J., Cheng, G., Shi, Y., Villalta, P.W., and Hecht, S.S. Identification of DNA adducts of acetaldehyde. Chem. Res. Toxicol., 13: 1149-1157, 2001. PubMed citation

Wang, M., Yu, N., Chen, L., Villalta, P.W., Hochalter, J.B., and Hecht, S.S. Identification of an acetaldehyde adduct in human liver DNA and quantitation as N² -ethyldeoxyguanosine. Chem. Res. Toxicol., 19: 319-324, 2006.  PubMed citation

Zhang, S., Villalta, P.W., Wang, M., and Hecht, S.S. Analysis of crotonaldehyde- and acetaldehyde-derived 1,N² -propanodeoxyguanosine adducts in DNA from human tissues using liquid chromatography-electrsopray ionization-tandem mass spectrometry. Chem. Res. Toxicol., 19: 1386-1392, 2006.  PubMed citation

Chen, L., Wang, M., Villalta, P.W., Luo, X., Feuer, R., Jensen, J., Hatsukami, D.K., and Hecht, S.S. Quantitation of an acetaldehyde adduct in human leukocyte DNA and the effect of smoking cessation. Chem. Res. Toxicol., 20: 108-113, 2007. PubMed citation

Zhang, S., Villalta, P., Wang, M., and Hecht, S.S. Detection and quantitation of acrolein-derived 1,N2-propanodeoxyguanosine adducts in human lung by liquid chromatography-electrospray ionization-tandem mass spectrometry. Chem. Res. Toxicol., 20: 565-571, 2007.  PubMed citation

Carmella, S.G., Chen, M., Zhang, Y., Zhang, S., Hatsukami, D.K., and Hecht, S.S. Quantitation of acrolein-derived 3-hydroxypropylmercapturic acid in human urine by liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry: effects of cigarette smoking. Chem. Res. Toxicol., 20: 986-990, 2007.  PubMed citation

Phenotyping human PAH metabolism
PAH are well-established environmental carcinogens that are probable causes of cancers of the lung, skin, and other tissues. Cytochrome P450 enzymes are involved in both the metabolic activation and detoxification of PAH in humans. Other enzymes such as epoxide hydrolase, glutathione-S-transferases, and UPD-glucuronosyltransferases are also involved in PAH metabolism. Inter-individual differences in the expression and activities of these enzymes are likely to affect cancer risk by modifying metabolic activation and detoxification pathways. We propose to quantify these differences by carcinogen metabolite phenotyping of human urine. We have developed methods to quantify metabolites phenanthrene, phenanthrene tetraol, and phenanthrols. Phenanthrene tetraol is the end-product of the diol epoxide metabolic activation pathway of PAH metabolism while phenanthrols result from detoxification. We are currently using this ratio to investigate PAH metabolism in humans in a variety of collaborative studies.

Suggested reading:

Hecht, S.S., Chen, M., Yagi, H., Jerina, D.M., and Carmella, S.G. r-1,t-2,3,c-4-Tetrahydroxy-1,2,3,4-tetrahydrophenanthrene in human urine: a potential biomarker for assessing polycyclic aromatic hydrocarbon metabolic activation. Cancer Epidemiol. Biomarkers & Prev., 12: 1501-1508, 2003. PubMed citation

Carmella S.G., Chen, M., Yagi H., Jerina, D.M. and Hecht, S.S. Analysis of phenanthrols in human urine by gas chromatography-mass spectrometry: potential use in carcinogen metabolite phenotyping. Cancer and Biomarkers & Prev.,13: 2167-2174, 2004. PubMed citation

Hecht, S.S., Chen, M. Yoder, A., Jensen, J., Hatsukami, D., Le, C. and Carmella, S.G. Longitudinal study of urinary phenanthrene metabolite ratios: effect of smoking on the diol epoxide pathway. Cancer Epidemiol. Biomarkers & Prev. 14: 2969-2974, 2005.  PubMed citation

Hecht, S.S., Carmella, S.G., Yoder, A., Chen, M., Li, Z., Le, C., Dayton, R., Jensen, J., and Hatsukami, D.K. Comparison of polymorphisms in genes involved in polycyclic aromatic hydrocarbon metabolism with urinary phenanthrene metabolite ratios in smokers. Cancer Epidemiol. Biomarkers & Prev., 15: 1805-1811, 2006.  PubMed citation

Carmella, S.G., Yoder, A., and Hecht, S.S. Combined analysis of r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in smokers' plasma. Cancer Epidemiol. Biomarkers & Prev., 15: 1490-1494, 2006.  PubMed citation

Upadhyaya, P., Rao, P., Hochalter, J.B., Li, Z., Villalta, P.W., and Hecht, S.S. Quantitation of N-acetyl-S-(9,10-dihydro-9-hydroxy-10-phenanthryl)-L-cysteine in human urine: comparison with glutathione-S-transferase genotypes in smokers. Chem. Res. Toxicol., 19: 1234-1240, 2006.  PubMed citation

Hecht, S.S., Villalta, P.W., and Hochalter, J.B. Analysis of phenanthrene diol epoxide mercapturic acid detoxification products in human urine: relevance to molecular epidemiology studies of glutathione-S-transferase polymorphisms. Carcinogenesis, in press, 2008.

Chemoprevention of lung cancer by isothiocyanates, indoles, and myo-inositol
Lung cancer is the leading cause of cancer death in the world. Chemoprevention is a viable approach to decreasing lung cancer risk and mortality in high risk people: addicted smokers and ex-smokers. Based on the epidemiologic observation that vegetables protect against lung cancer, we are investigating the use of mixtures of bioactive vegetable constituents as chemopreventive agents for smokers and ex-smokers. Our focus is on naturally occurring compounds and their derivatives with established chemopreventive activity against lung cancer in animal models: isothiocyanates, their N-acetylcysteine conjugates, indole-3-carbinol, and myo-inositol. Current efforts are focused on mixtures of phenethyl isothiocyanate-N-acetylcysteine-(PEITC-NAC), benzyl isothiocyanate (BITC), and myo-inositol. Efficacy studies are being carried out in mice treated with tobacco carcinogens or tobacco smoke, and proteomic analyses of tissues of treated mice and rats are being performed to determine mechanistically important pathways and identify potential biomarkers of efficacy.

Suggested reading:

Hecht, S.S. Inhibition of carcinogenesis by isothiocyanates. Drug Metabol. Rev., 32: 395-411, 2000. PubMed citation

Hecht, S.S., Huang, C., Stoner, G.D., Li, J., Kenney, P.M.J., Sturla, S.J., and Carmella, S.G. Identification of cyanidin glycosides as constituents of freeze-dried black raspberries which inhibit anti-benzo[a]pyrene-7,8-diol-9,10-epoxide induced NFκB and AP-1 activity. Carcinogenesis, 27: 1617-1626, 2006.  PubMed citation

Kassie, F., Anderson, L., Scherber, R., Yu, N., Lahti, D., Upadhyaya, P., and Hecht, S.S. Indole-3-carbinol inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone plus benzo[a]pyrene-induced lung tumorigenesis in A/J mice and modulates carcinogen-induced alterations in protein levels. Cancer Res., 67: 6502-6511, 2007.  PubMed citation

Kassie, F., Anderson, L.B., Higgins, L., Pan, Y., Matise, I., Negia, M., Upadhyaya, P., Wang, W., and Hecht, S.S.. Chemopreventive agents modulate the protein expression profile of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone plus benzo[a]pyrene-induced lung tumors in A/J mice. Carcinogenesis, epub ahead of print Jan 12, 2008. PubMed citation

Kassie, F., Matise, I., Negi, M., Lahti, D., Pan, Y., Scherber, R., Upadhyaya, P., and Hecht, S.S. Combinations of N-acetyl-S-(N-2-phenethylthiocarbamoyl)-L-cysteine and myo-inositol inhibit tobacco smoke carcinogen-induced lung adenocarcinoma in A/J mice. Cancer Prev. Res., submitted, 2008.