Differentiation-dependent expression of provirus-activated int-1 oncogene in clonal cell lines derived from a mouse mammary tumor

E Schuuring, B J van der Leede, R Willems, H Daams, M van der Valk, M van de Vijver, F van Leeuwen, A Sonnenberg, R Nusse

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11 Citations (Scopus)


The int-1 mammary oncogene is frequently activated by proviral insertion in mouse mammary tumors. To characterize the target cell for the oncogenic action of int-1, we have isolated permanent cell lines with distinct morphologies and differentiation characteristics, starting from a tumor with a rearranged int-1 gene. Polygonal cells had retained many differentiation markers of epithelial cells and produced adenocarcinomas upon transplantation in syngenic mice. Sphere-forming-cuboidal cells are poorly differentiated and produced anaplastic tumors. Cuboidal and elongated cells were negative for epithelial markers. Cuboidal cells were poorly tumorigenic, but elongated cells produced highly malignant sarcoma-like tumors. In all lines, the int-1 gene was identically rearranged due to insertion of proviral DNA of the Mouse Mammary Tumor Virus, but the expression of int-1 varied with the state of differentiation of the cells. Polygonal cells contained relatively high levels of int-1 RNA, which were not influenced by steroid hormones. In the sphere-forming-cuboidal cells, expression of int-1 was low but inducible by dexamethasone. In the cuboidal and elongated cells no expression of int-1 was detectable, showing that the continued expression of int-1 was not required for progression to more malignant cells. By immunoprecipitation, two int-1 protein species, of 42 and 40 kD were identified in polygonal and in sphere-forming-cells but not in the culture media.

Original languageEnglish
Pages (from-to)459-65
Number of pages7
Issue number4
Publication statusPublished - Apr 1990
Externally publishedYes


  • Adenocarcinoma/genetics
  • Animals
  • Cell Differentiation
  • Cell Line
  • Clone Cells
  • DNA, Neoplasm/genetics
  • Gene Expression
  • Mammary Neoplasms, Experimental/genetics
  • Mice
  • Mice, Inbred C3H
  • Oncogene Proteins, Viral/genetics
  • Oncogenes
  • Proviruses/genetics


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