The central hypothesis of this application is that growth regulating pathways expressed in human and mouse alveolar type II cell pulmonary adenocarcinomas (PAC type II) and in human and hamster pulmonary squamous cell carcinomas (SQCs) are antagonistic to those expressed in human and hamster Clara cell type pulmonary adenocarcinomas (PACCs). Chemoprevention studies applicable to former smokers therefore need to use models representing these differently regulated cancer types. Non-invasive methods need to be developed that allow to monitor the expression levels of these pathways in former smokers to asses response to treatment and to ensure assignment of individuals to effective chemopreventive treatments while avoiding potentially cancer promoting agents. To achieve these goals in a preclinical setup, our specific aims are as follows: 1) We will characterize the effects of green tea, theophylline, beta-carotene, retinol, glucocorticoid beta- blockers, cAMP antaogonists, and inhibitors of cyclooxygenase-2 (COX-2) or 5-1ipooxygenase (5-.LOX) in human lung cancer cell lines derived from PAC type II, PACC or QSQC and in non-tumorigenic and tumorigenic mouse PAC type II cell lines. 2) We will synthesize iodine-125 and -123-labeled analogues of inhibitors of COX-2, cAMP-dependent PKA and 5-LOX for use in micro-photon emisssion tomography (micro-SPECT). We will verify the binding of these analogues to their cellular targets by in vitro binding assays, using human lung cancer cell lines characterized under aim 1 and by in vivo bio-distribution studies, using mice carrying xenographs of these human lung cancer cell lines. 3) We will study the chemopreventive effects of selected agents from aim 1 in bioassay experiments, using the A/J/mouse PAC type II model, the hamster PACC model and the hamster SQC model. The experimental designs will simulate chemoprevention in former smokers by starting the chemopreventive treatments at the time when tumor induction treatment has been discontinued and precancerous lesions are present in the animals. Evaluation of data will include histopathology, including immunostains for COX-2, PKA and 5-LOX as well as analysis of protein expression of these enzymes by Western blots in normal cells of origin of the induced tumors, premalignant lesions, and in lung cancers harvested by laser capture microscopy. 4) Using the iodine-125-1abeled analogues from aim 2, we will conduct micro-SPECT analysis of five randomly chosen animals per treatment group of aim 3 before, during and after completion of chemopreventive treatments and we will attempt to quantitate levels of COX-2, PKA, and 5-LOX in lung tissues and lung tumors.
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