Preclinical data suggest that the cyclooxygenase (COX)-2/prostaglandin (PG) E2 signaling pathway plays an essential role in conferring the malignant phenotype in non-small cell lung cancer. We hypothesized that treatment with oral celecoxib, a selective COX-2 inhibitor, would favorably alter biomarkers of lung cancer risk. This study evaluated the feasibility of COX-2 inhibition as a form of chemoprevention for lung cancer. Heavy active smokers were enrolled into a pilot study and treated with

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... elecoxib. Bronchoscopy with bronchoalveolar lavage was performed both before and after 1 month of celecoxib treatment to recover alveolar macrophages (AMs) and lining fluid for study. After harvest, AMs were immediately stimulated in vitro with the calcium ionophore A23187. AMs obtained from smokers before treatment and from nonsmoking control subjects were also cultured overnight with SC58236, a selective COX-2 inhibitor, with or without lipopolysaccharide stimulation. Treatment with celecoxib significantly reduced calcium ionophore-stimulated PGE2 production from AMs recovered from smokers. AMs recovered from smokers, but not nonsmokers, were primed to produce high levels of PGE2 and interleukin (IL-10) when stimulated with lipopolysaccharide, and SC58236 significantly abrogated the production of these factors. Moreover, both plasma and bronchoalveolar lavage fluid obtained from treated subjects significantly reduced the production of PGE2 that resulted when a lung cancer cell line, A549, was stimulated with IL-1beta or A23187. Our findings suggest that oral celecoxib is capable of inhibiting the overproduction of PGE2, as well as modulating the production of IL-10 in the lung microenvironment in individuals at risk for lung cancer.