Studies in a Rat Lung Tumor Model: Cellular Biochemistry and Cytogenetics
Abstract
Dose-response relationships were established for the induction of 3- methyl-cholanthrene (MCA) of squamous cell carcinomas (SCC) in rat lung. Five biweekly intratracheal inoculations of 0.25, 0.5, 1.0, or 5.0 mg MCA gave tumor yields of 8%, 16%, 48%, and 100%, respectively, in treatment groups of 25 rats each. No tumors were seen in control rats or in rats treated 5 times with 0.1 mg MCA. Studies of sister chromatid exchange (SCE) incidence in lung cell cultures and in peripheral lymphocytes of rats treated intratracheally with tumorigenic doses of MCA showed elevated frequencies of SCEs in the lung cells, but not in peripheral lymphocytes. The increased level of SCEs in the lung cells did not persist, but declined in parallel with the clearance of MCA from the lungs over a period of about 6-8 weeks. The conclusions were that SCE incidence in peripheral lymphocytes could not be used to predict a carcinogenic hit in the lung as the result of MCA treatment, and the elevation of SCE frequency in lung cells was dependent on the presence of MCA immediately prior to performing the assay. Preliminary results of studies in which rats were treated with MCA and/or asbestos indicated that cytotoxic effects in the lung were different for the 2 materials. MCA tended to produce lesions at the terminal bronchioles and asbestos caused focal areas of fibrosis. Experiments in progress will indicate whether a cocarcinogenic action of the materials may occur in the rat lung tumor model.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1983
- Accession Number
- ADA132942
Entities
People
- Ronald E. Rasmussen
Organizations
- University of California, Irvine