Expression of mammary tumor virus proteins in preneoplastic outgrowth lines and mammary tumors of BALB/cV mice.
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 to 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 antigenpositive 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 MMTVs. These studies demonstrate that 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.
D000818:Animals; D002460:Cell Line; D005260:Female; D007106:Immune Sera; D008325:Mammary Neoplasms, Experimental / Q000382:microbiology*; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D011230:Precancerous Conditions / Q000382:microbiology*; D014764:Viral Proteins / Q000235:genetics* / Q000302:isolation & purification
D007106:Immune Sera; D014764:Viral Proteins