This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Smith, T. J. Articles by Yang, C. S. Search for Related Content PubMed PubMed Citation Articles by Smith, T. J. Articles by Yang, C. S.

Activation of 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in Human Lung Microsomes by Cytochromes P450, Lipoxygenase, and Hydroperoxides¹

Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, New Jersey 08855-0789 [T. J. S., C. S. Y.], and Department of Preventive Medicine, Arthur James Cancer Hospital and Research Institute, Ohio State University, Columbus, Ohio 43210-1240 [G. D. S.]

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent tobacco-specific carcinogen, has been demonstrated to induce lung tumors in animals and is suspected to be a human carcinogen. Cytochromes P450 are the major enzymes responsible for the activation of NNK in microsomes from the lung and liver of rat and mouse, as well as human liver. The present study investigated the enzymes responsible for the metabolic activation of NNK in human lung microsomes. In the presence of a NADPH-generating system, the formation of keto aldehyde and keto alcohol (-hydroxylation products, measured together), keto acid, hydroxy acid, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol was observed in human lung microsomes. Carbon monoxide (90%) decreased the rate of NNK oxidation by 5–49%, depending on the human lung microsomal samples analyzed. Coumarin decreased the oxidation of NNK by 9–34%, and an antibody against human P450 2A6 decreased the metabolism of NNK by 8–37%, suggesting the involvement of P450 2A6 in NNK oxidation. -Napthoflavone inhibited NNK oxidation by 6–26%, possibly due to the inhibition of P450 1A1. P450 1A1-expressed microsomes catalyzed the formation of keto aldehyde and keto alcohol, exhibiting K_m values of 1400 µM and 371 µM, respectively. In the absence of NADPH, NNK metabolism resulted in the formation of keto acid, keto aldehyde, and keto alcohol, and the activities in different lung samples were decreased by indomethacin (100 µM; cyclooxygenase inhibitor) or nordihydroguaiaretic acid (100 µM; lipoxygenase inhibitor) by 0–27% or 30–66%, respectively. The addition of arachidonic acid (10–100 µM) increased the rate of the formation of keto aldehyde and keto alcohol approximately 2-fold but inhibited the formation of keto acid. Soybean lipoxygenase increased the rate of formation of keto aldehyde and keto alcohol in a concentration-dependent manner. The increased rate in NNK oxidation by arachidonic acid or lipoxygenase was inhibited completely by nordihydroguaiaretic acid. Catalase, thiourea, and conjugated linoleic acid decreased the rate of NNK oxidation by 47, 20, and 45%, respectively. tert-Butyl-hydroperoxide, cumene hydroperoxide, and hydrogen peroxide increased the rate of formation of keto aldehyde and keto alcohol by 210, 40, and 50%, respectively. The results suggest that P450 enzymes are only partially responsible for the activation of NNK in human lung microsomes, and P450 2A6 or a P450 2A6-related enzyme seems to be involved in the activation. Furthermore, lipoxygenase and lipid hydroperoxides may play important roles in the oxidation of NNK in human lung microsomes.

¹ This study was supported by NIH Grants CA46535, CA37037 and CA44353, and National Institute of Environmental Health Sciences Center Grant ES05022.

² To whom requests for reprints should be addressed, at Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, NJ 08855-0789. Phone: (908) 445-5361; Fax: (908) 445-0687.

Received 8/15/94. Accepted 10/ 3/95.

This article has been cited by other articles:

				X. Zhang, J. D'Agostino, H. Wu, Q.-Y. Zhang, L. von Weymarn, S. E. Murphy, and X. Ding CYP2A13: Variable Expression and Role in Human Lung Microsomal Metabolic Activation of the Tobacco-Specific Carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone J. Pharmacol. Exp. Ther., November 1, 2007; 323(2): 570 - 578. [Abstract] [Full Text] [PDF]

				P. J. Brown, L. L. Bedard, K. R. Reid, D. Petsikas, and T. E. Massey Analysis of CYP2A Contributions to Metabolism of 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone in Human Peripheral Lung Microsomes Drug Metab. Dispos., November 1, 2007; 35(11): 2086 - 2094. [Abstract] [Full Text] [PDF]

				H. H. Yoo, M. W. Lee, Y. C. Kim, C.-H. Yun, and D.-H. Kim Mechanism-Based Inactivation of Cytochrome P450 2A6 by Decursinol Angelate Isolated from Angelica Gigas Drug Metab. Dispos., October 1, 2007; 35(10): 1759 - 1765. [Abstract] [Full Text] [PDF]

				U. Breyer-Pfaff, H.-J. Martin, M. Ernst, and E. Maser ENANTIOSELECTIVITY OF CARBONYL REDUCTION OF 4-METHYLNITROSAMINO-1-(3-PYRIDYL)-1-BUTANONE BY TISSUE FRACTIONS FROM HUMAN AND RAT AND BY ENZYMES ISOLATED FROM HUMAN LIVER Drug Metab. Dispos., September 1, 2004; 32(9): 915 - 922. [Abstract] [Full Text] [PDF]

				L.-I. Proulx, A. Castonguay, and E. Y. Bissonnette Cytokine production by alveolar macrophages is down regulated by the {alpha}-methylhydroxylation pathway of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) Carcinogenesis, June 1, 2004; 25(6): 997 - 1003. [Abstract] [Full Text] [PDF]

				G. B. J. Smith, J. R. Bend, L. L. Bedard, K. R. Reid, D. Petsikas, and T. E. Massey BIOTRANSFORMATION OF 4-(METHYLNITROSAMINO)-1-(3-PYRIDYL)-1-BUTANONE (NNK) IN PERIPHERAL HUMAN LUNG MICROSOMES Drug Metab. Dispos., September 1, 2003; 31(9): 1134 - 1141. [Abstract] [Full Text] [PDF]

				N. Ariyoshi, M. Miyamoto, Y. Umetsu, H. Kunitoh, H. Dosaka-Akita, Y.-i. Sawamura, J. Yokota, N. Nemoto, K. Sato, and T. Kamataki Genetic Polymorphism of CYP2A6 Gene and Tobacco-induced Lung Cancer Risk in Male Smokers Cancer Epidemiol. Biomarkers Prev., September 1, 2002; 11(9): 890 - 894. [Abstract] [Full Text] [PDF]

				B. Prokopczyk, N. Trushin, J. Leszczynska, S. E. Waggoner, and K. El-Bayoumy Human cervical tissue metabolizes the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, via {{alpha}}-hydroxylation and carbonyl reduction pathways Carcinogenesis, January 1, 2001; 22(1): 107 - 114. [Abstract] [Full Text] [PDF]

				N. Rioux and A. Castonguay The induction of cyclooxygenase-1 by a tobacco carcinogen in U937 human macrophages is correlated to the activation of NF-{kappa}B Carcinogenesis, September 1, 2000; 21(9): 1745 - 1751. [Abstract] [Full Text] [PDF]

				T. Su, Z. Bao, Q.-Y. Zhang, T. J. Smith, J.-Y. Hong, and X. Ding Human Cytochrome P450 CYP2A13: Predominant Expression in the Respiratory Tract and Its High Efficiency Metabolic Activation of a Tobacco-specific Carcinogen, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone Cancer Res., September 1, 2000; 60(18): 5074 - 5079. [Abstract] [Full Text]

				S. S. Hecht, N. Trushin, S. K. Chhabra, L. M. Anderson, and P. V. Nerurkar Short Communication: Metabolism of 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone by Cultured Monkey Lung Explants Drug Metab. Dispos., January 1, 2000; 28(1): 5 - 9. [Abstract] [Full Text]

				G. B.J. Smith, A. Castonguay, P. J. Donnelly, K. R. Reid, D. Petsikas, and T. E. Massey Biotransformation of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in freshly isolated human lung cells Carcinogenesis, September 1, 1999; 20(9): 1809 - 1818. [Abstract] [Full Text] [PDF]

				H. M. Schuller, P. K. Tithof, M. Williams, and H. Plummer III The Tobacco-specific Carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone Is a {beta}-Adrenergic Agonist and Stimulates DNA Synthesis in Lung Adenocarcinoma via {beta}-Adrenergic Receptor-mediated Release of Arachidonic Acid Cancer Res., September 1, 1999; 59(18): 4510 - 4515. [Abstract] [Full Text] [PDF]

				S. S. Hecht Tobacco Smoke Carcinogens and Lung Cancer J Natl Cancer Inst, July 21, 1999; 91(14): 1194 - 1210. [Abstract] [Full Text] [PDF]

				M. Meger, E. Richter, W. Zwickenpflug, C. Oehlmann, M. B. Hargaden, Y. I. A-Rahim, and E. S. Vesell Metabolism and Disposition of 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone (NNK) in Rhesus Monkeys Drug Metab. Dispos., April 1, 1999; 27(4): 471 - 478. [Abstract] [Full Text]

				K. El-Bayoumy, M. Iatropoulos, S. Amin, D. Hoffmann, and E. L. Wynder Increased Expression of Cyclooxygenase-2 in Rat Lung Tumors Induced by the Tobacco-specific Nitrosamine 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanone: The Impact of a High-Fat Diet Cancer Res., April 1, 1999; 59(7): 1400 - 1403. [Abstract] [Full Text] [PDF]

				M. E. Staretz, S. E. Murphy, C. J. Patten, M. G. Nunes, W. Koehl, S. Amin, L. A. Koenig, F. P. Guengerich, and S. S. Hecht Comparative Metabolism of the Tobacco-Related Carcinogens Benzo[a]pyrene, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol, and N'-Nitrosonornicotine in Human Hepatic Microsomes Drug Metab. Dispos., February 1, 1997; 25(2): 154 - 162. [Abstract] [Full Text]