EXPRESSION OF MAMMARY-TUMOR VIRUS PROTEINS IN PRENEOPLASTIC OUTGROWTH LINES AND MAMMARY-TUMORS OF BALB/CV MICE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 44  (5) , 2155-2162
Abstract
A subline of BALB/c mice, designated BALB/cV, has been segregated which exhibits an intermediate mammary tumor incidence and which harbors a unique milk-transmitted virus. Six stable hyperplastic alveolar nodule outgrowth lines were established from chemical carcinogen-treated and hormonally stimulated mice. Tumor incidences exhibited by the individual preneoplastic lines ranged from 22-95%, no differences in tumor-producing capability were observed when lines were transplanted in virus-negative (BALB/c) or virus-positive (BALB/cV) animals. Viral antigen expression was monitored using antisera prepared against C3H mouse mammary tumor virus (MMTV) proteins. The preneoplastic lines exhibited more virus antigen-positive cells in a peroxidase-antiperoxidase immunocytochemical assay than did primary tumors which arose from the hyperplastic alveolar nodule transplants. Analysis of BALB/cV preneoplastic and tumor tissue by metabolic labeling and by protein electroblotting methodologies revealed that viral precursor and structural proteins were expressed in both types of tissue; the polypeptides were similar in molecular weight to those encoded by exogenous MMTV [mouse mammary tumor virus]. The coding capacity of the BALB/cV isolate of MMTV is similar to that of known MMTV isolates and that each of the BALB/cV structural polypeptides shares group-specific antigenic determinants with the analogous protein encoded by MMTV from the C3H mouse. The hyperplastic outgrowth lines established in the BALB/cV subline provide an additional system for the study of mammary tumorigenesis.