Oncogenicity of the R-35 Rat Mammary Tumor Virus2

Autor: William R. Cobb, Marcus M. Mason, Bogden Ae, Mumtaz Ahmed, Sharon Alex
Rok vydání: 1974
Předmět:
Zdroj: JNCI: Journal of the National Cancer Institute. 53:1073-1077
ISSN: 1460-2105
0027-8874
DOI: 10.1093/jnci/53.4.1073
Popis: Observed oncogenicity of the R-35 MTV virus as shown by the mammary tumor incidence in female rats inoculated neonatally is reported. The R-35 mammary tumor virus (R-35 MTV) is a C-type virus originally isolated from the R-35 mammary adenocarcinoma. Rat neonates were obtained from Sprague-Dawley derived females. This particular stock (GFRC:SPF(SD)) is negative for known rodent virus and is almost 100 percent susceptible to grafts of R-35 mammary adenocarcinoma. Male and female neonates 24-48 hours old were inoculated sc; control animals were not inoculated. During a 20-month observation period overall mammary tumor incidence in the inoculated female group was 29.5 percent and in the control group 18.5 percent. Benign tumors were of about equal frequency 16.7 and 18. 7 percent respectively. Malignant tumors were only 1.8 percent in controls but 10.8 percent in inoculated rats (p smaller than .05). Malignant tumors appeared at 4-5 months in virus-treated rats but not until 9-13 months in controls. These tumors were mostly of epithelial cell origin. No tumors were found at the site of inoculation. No mammary tumors were found in virus-inoculated males. Estrogen imbalance brought about by implantation of 17beta-estradiol pellets and hysterectomy was followed by a mammary adenocarcinoma incidence of 35 percent among 20 virus-inoculated rats within 13 months but no tumors in a control group of 21 animals. Of 8 tumors from animals given virus implants all had R-35 MTV antigen and 3 had C-type particles as seen by electron microscopy. In 5 tumors from controls no antigen or C-type particles were found. Leukemia was not found in any of 315 virus-inoculated or in 247 control rats. Estrogen imbalance may be cocarcinogenic with R-35 MTV virus infection in mammary tumorigenesis. The absence of mammary tumors in R-35 MTV inoculated males also suggests a cofactor function for mammotrophic hormones.
Databáze: OpenAIRE
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