This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rashad, A. L. Articles by Evans, C. A. Search for Related Content PubMed PubMed Citation Articles by Rashad, A. L. Articles by Evans, C. A.

A Difference in Sites of DNA Synthesis in Virus-induced (Shope) and in Chemically Induced Epidermal Tumors of Rabbit Skin¹

School of Medicine, Department of Microbiology, University of Washington, Seattle, Washington 98105

Following in vivo or in vitro exposure to thymidine-³H, a radioautographic difference was detected between virus-induced and chemically induced papillomas and carcinomas of the skin of rabbits. Label indicative of DNA synthesis was present in well-differentiated granular cells and in cells adjacent to the horny layer in the virus-induced tumors, but not in the chemically induced rabbit tumors, or in the normal rabbit skin. This pattern of DNA synthesis was detected in all of the 10 Shope papillomas and in 2 out of the 4 Shope primary carcinomas tested. The percentage of labeled cells in the granular layer, however, was higher in cottontail than in domestic rabbit papillomas, and in the latter it was higher than in primary skin carcinomas. In 16 7,12-dimethylbenz()anthracene (DMBA) papillomas, 4 DMBA skin carcinomas, and a variety of normal rabbit stratified squamous epithelia, the label was limited to basal and parabasal cells. No label could be detected in the granular cells or in cells near the surface.

The rabbit kidney vacuolating (RKV) virus, which was present as a contaminant in some of the Shope papillomas, did not seem to be responsible for the granular cell label since this label could always be detected in the Shope papillomas regardless of whether or not they harbored the RKV virus. Similarly, DMBA rabbit tumors, naturally or artificially contaminated with RKV virus, showed no label in the granular cells.

The available evidence indicates that the granular cell label of Shope tumors could be due to Shope papilloma virus (SPV)-DNA synthesis, cellular DNA synthesis induced by SPV, or a combination of both. Regardless of whether virus or cellular in origin, the presence of label in a granular cell is a sign indicative of infection with SPV, and is useful in distinguishing between virus-induced and chemically induced skin papillomas and carcinomas of rabbits.

¹ This research was supported in part by Research Grant CA 02668 from the National Cancer Institute, NIH, USPHS.

Received 3/ 1/67. Accepted 5/11/67.