An RCDA is requested to relieve a heavy teaching load, and allow full-time research on the project described below as well as time to gain experience in recombinant DNA technology and apply this to lung adenomas. By comparing the effects of the carcinogen, urethane, with those of the lung-toxic and tumor promoting agent, butylated hydroxytoluene (BHT), in mouse strains with different susceptibilities to adenoma formation, we will distinguish biochemical changes unique to neoplasia from those characteristic of a normal proliferative response. The cellular origin of the adenomas induced by urethane in adult Strain A mice is the Type 2 alveolar cell, but adenonas can also arise from Clara cells. The effect of strain, age and carcinogen on adenoma origin will be determined. A single dominant gene in BALB mice which confers resistance to adenomas will be used to differentiate toxic effects of urethane from truly neoplastic ones, and will be mapped using recombinant inbred mice. We will determine whether this gene prevents formation of hyperplastic foci or their further progression. Transplantation studies with dissected embryonic rudiments will determine if this gene acts on epithelial or mesenchymal tissue. The mechanisms by which BHT enhances adenoma formation will be studied using the sensitive analytical techniques, HPLC and GC/MS, to analyze the BHT metabolites produced in vivo and in vitro. The toxic and tumor promoting effects of BHT vary between inbred strains, species and organs. By comparing the metabolites produced in a variety of systems with the physiological effects of BHT in that system, we hope to clearly identify and distinguish between the toxic and tumor promoting derivations of this compound. Adenoma cAMP receptors have a decreased ability to bind the photoaffinity analog, 8-N3-cAMP, and have lost the ability for cAMP to stimulate autophosphorylation. Such changes will be looked for in isolated Type 2 cells at earlier stages of carcinogenesis. Antibodies will be prepared against the R-subunits of cAMP-dependent protein kinases, and used to determine changes in subunit concentrations and turnover rates. The physiological consequence of this loss of receptor sensitivity will be studied in Type 2 cells by monitoring the ability of cAMP to stimulate endogenous protein phosphorylation. Correlation between the activity of protein kinases activated by Ca++ and phospholipids in different strains and the susceptibility of these strains to adenoma induction will be thoroughly investigated, since this kinase may be involved in progression of initiated cells. A photoaffinity analog of cyclic GMP, 8-N3-(32p)cGMP, will be used to monitor the kinases activated by cyclic GMP, which change during normal development and regenerative lung cell division.
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