Abstract 5558: Persistent induction of cytochrome P450 (CYP)1A1 in human lung cell line, H358, by 3-methylcholanthrene: Implications for pulmonary carcinogenesis by polycyclic aromatic hydrocarbons

Abstract

Abstract Humans are constantly exposed to environmental carcinogenic polycyclic aromatic hydrocarbons (PAHs) through cigarette smoke, diesel exhausts, charcoal-broiled meats, etc. Cytochrome P4501A (CYP1A) enzymes play important roles in the activation of PAHs such as 3-methylcholanthrene (MC) to carcinogenic DNA-binding metabolites, which could in turn lead to pulpmnary carcinogenesis. We recently reported that MC elicits persistent induction of hepatic and pulmonary CYP1A1 in mice by mechanisms other than persistence of the parent MC, and that this phenomenon contributes to pulmonary carcinogenesis. The regulation of CYP1A1 in human lung is not well understood as MC fails to induce CYP1A1 in many lung cells lines, including A549 cells. In this study, we tested the hypothesis that MC elicits persistent induction of CYP1A1 in the human bronchoalveolar cell line, H358. H358 cells were exposed to MC (2.5 µM) dissolved in DMSO, or DMSO alone as controls. At different time points, CYP1A1 activities were determined by measuring the activities of ethoxyresorufin O-dethylase (EROD). CYP1A1 apoprotein and mRNA expression were determined by Western blotting and real time RT-PCR, respectively. MC induced CYP1A1 activities by 8-fold at 8 h, and this effect was persistent even at 72 h. This was accompanied by persistent expression of CYP1A1 apoprotein. Real-time RT-PCR showed that 8 h treatment with 2.5 µM MC induced mRNA of CYP1A1 by 850-fold, and the effect was persistent up to 72 h. These results suggest that the H358 cell line could be an excellent model to study the molecular mechanisms of CYP1A1 regulation by MC in the human lung. Since lung is a target organ for pulmonary carcinogenesis in humans exposed to environmental pollutants such as cigarette smoke, further studies could lead to improved understanding of the mechanisms of pulmonary carcinogenesis, which could in turn lead to the development of rational strategies for the prevention/treatment of lung cancers in humans. (Supported by NIH grant ES009132.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5558. doi:10.1158/1538-7445.AM2011-5558