Oncogenes Activated in Radiation-Induced Rat Skin Tumors
Male, Sprague-Dawley rats were exposed at four weeks of age to 0.8 MeV electron radiation in single or fractionated doses ranging from 800 to 1600 rads. A sample of 6 tumors was excised at 50 or 74 weeks of age. The DNA from three carcinomas produced transformed foci by transfection in NIH3T3 cells. In 4 transfectants a rat tumor derived K-ras Eco R1 fragment was seen by Southern blot analysis. The DNA of four cancers showed myc gene amplification in each case compared to normal rat liver DNA. Hybridization with an H-ras probe showed no significant amplification of this gene in any of the tumors. Northern blot analysis of poly A+ RNA demonstrated a major increase of myc gene expression in a tumor which was active in the transfection assay. Analogous experiment using the same mRNA samples showed no differences in H-ras gene expression between normal skin and any tumor. These data demonstrate simultaneous activation of oncogenes from myc and ras complementation groups in a single tumor.
KeywordsNIH3T3 Cell Transfection Assay Sebaceous Carcinoma Radiation Induce Tumor Radiation Carcinogenesis
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- 1.F. J. Burns and R. E. Albert, in: “Radiation Carcinogenesis,” A. Upton, F. Burns, and R. Shore, eds., Elsevier Science Publishing Co., New York, New York (1985), in press.Google Scholar
- 3.H. P. Lennhouts and K. H. Chadwick, Theor. Appl. Genet. 44:167–172 (1974).Google Scholar
- 29.G. P. Margison and P. J. O’Connor, in: “Chemical Carcinogenesis and DNA, Vol. 1,” P. L. Grover, CRC Press, Boca Raton, Florida (1979), pp. 111–159.Google Scholar
- 32.S. J. Garte, A. T. Hood, A. E. Hochwalt, C. A. Snyder, and A. Segal, Proc. Amer. Assoc. Cancer Res. (1985), in press.Google Scholar
- 34.I. Berenblum, and P. Shubik, Br.J. Cancer 1:388 (1947).Google Scholar