Myeloperoxidase-enhanced formation of (±)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a] pyrene adducts in lung tissue in vitro: A role of pulmonary inflammation in the bioactivation of a procarcinogen

Janet M. Petruska, D. Randolph Mosebrook, George J. Jakab, Michael A. Trush

Research output: Contribution to journalComment/debatepeer-review

Abstract

Several studies have indicated a correlation between the presence of inflammation and the development of cancer. The aim of our study was to determine if pulmonary neutrophils could transform the proximate respiratory carcinogen (±)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (B[a] 7,8-diol), to an ultimate carcinogenic metabolite via myeloperoxidase (MPO). To test this hypothesis, virus-free male DBA/2 mice were exposed by inhalation to the Gram-negative bacteria Proteus mirabilis for 1 h. For various time points post-exposure, bronchoalveolar lavage (BAL) was performed to determine total and differential cell counts, cellular MPO activity and production of superoxide. Twelve hours after the exposure, cellular activity of MPO as well as percentage and total number of polymorphonuclear leukocytes peaked and declined thereafter. At this same time point, cells from BAL exhibited increased release of superoxide, as measured by reduction of cytochrome c, after addition of soluble or particulate stimuli, 12-O-tetradecanoylphorbol-13-acetate (TPA) or opsonized zymosan respectively. These cells also elicited biotransformation of B[a]P-7,8-diol as evidenced by enhanced B[a]P-7,8-diol-derived chemiluminescence, tetraol formation and covalently bound adduct formation to exogenous DNA upon addition of TPA or opsonized zymosan. Moreover, the cell-free BAL fluid of infected mice contained substantial MPO activity in comparison to that of uninfected animals. Also, MPO enhanced the binding of B[a]P-7,8-diol to lung DNA in vitro. Unlike previous work emphasizing the potential roles of oxygen free radicals in tumor promotion, our results indicate a role of neutrophilic MPO in the initiation of carcinogenesis.

Original languageEnglish (US)
Pages (from-to)1075-1081
Number of pages7
JournalCarcinogenesis
Volume13
Issue number7
DOIs
StatePublished - Jul 1992

ASJC Scopus subject areas

  • Cancer Research

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