Mammary cancer stages in BALB/cV mice: mouse mammary tumor virus expression and virus-host interactions

J Natl Cancer Inst. 1987 Aug;79(2):323-35.


A unique subline of BALB/c mice, designated "BALB/cV," exhibits an intermediate mammary tumor incidence (47%) and harbors a distinct milk-transmitted mouse mammary tumor virus (MMTV). Virus expression and virus-host interactions were examined during the different stages of mammary tumorigenesis (normal, preneoplastic, and neoplastic) in the BALB/cV system. Protein immunoblot analyses established the presence of correctly processed (BALB/cV)MMTV structural proteins in all types of BALB/cV mammary tissues. Competition enzyme-linked immunosorbent assays demonstrated that cells from each biologic phenotype were capable of supporting high levels of (BALB/cV)MMTV protein expression. However, mammary epithelial cells that spontaneously underwent the inappropriate pathway of squamous metaplasia did not contain detectable levels of (BALB/cV)MMTV structural proteins. Iodination experiments revealed the presence of a 68K env-related protein on the surface of BALB/cV mammary cells. Nevertheless, sera from 40 mice bearing BALB/cV-positive mammary tissues did not contain detectable levels of anti-env antibodies. Metabolic labeling experiments showed that the half-life of transformation-related, host cell protein p53 (approximately equal to 60 min) in the distinct BALB/cV mammary cell populations was similar to that reported for normal mouse 3T3 cells. It appears that p53 is not stabilized by protein interactions involving any MMTV-encoded or MMTV-induced protein in mammary tumor cells. These characteristics of the BALB/cV system are compatible with the hypothesis that MMTV is only one of two or more cooperating factors required to mediate complete mammary transformation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Viral / analysis
  • Cell Differentiation
  • Electrophoresis, Polyacrylamide Gel
  • Mammary Glands, Animal / microbiology
  • Mammary Neoplasms, Experimental / metabolism
  • Mammary Neoplasms, Experimental / microbiology*
  • Mammary Tumor Virus, Mouse / immunology
  • Metaplasia / microbiology
  • Mice
  • Mice, Inbred BALB C
  • Neoplasm Proteins / analysis
  • Neoplasm Staging
  • Phenotype
  • Phosphoproteins / analysis
  • Tumor Suppressor Protein p53
  • Viral Envelope Proteins / immunology


  • Antibodies, Viral
  • Neoplasm Proteins
  • Phosphoproteins
  • Tumor Suppressor Protein p53
  • Viral Envelope Proteins