title: Induction of clonal monocyte-macrophage tumors in vivo by a mouse c-myc retrovirus: rearrangement of the CSF-1 gene as a secondary transforming event.
abstract: A mouse retrovirus containing the c-myc oncogene was found to induce tumors of mononuclear phagocytic cells in vivo. All tumors expressed the c-myc retroviral gene but not the endogenous c-myc gene (with one exception), and virtually all tumors were clonal with a unique proviral integration. This observation, coupled with a lag time in tumor formation, suggests that a second event, in addition to c-myc proviral integration, is necessary for the generation of neoplastic cells in vivo. All of the tumor cells expressed high levels of mRNA for both the putative colony-stimulating factor 1 (CSF-1) receptor (c-fms proto-oncogene product), as well as the c-fos proto-oncogene. Although all of the tumor cells proliferated in culture without the addition of exogenous CSF-1, which is required for the proliferation of primary macrophages partially transformed by the same c-myc retrovirus, several phenotypes were observed with respect to the expression of CSF-1 and granulocyte-macrophage CSF and to their growth factor responsiveness. The proliferation of one tumor, which secreted high levels of CSF-1, was blocked by specific anti-CSF-1 serum. This tumor was found to express altered CSF-1 mRNA and to have a DNA rearrangement at the CSF-1 locus. In this particular case, the data indicate that a CSF-1 gene rearrangement was the secondary event in development of the tumor. The pleiotropy of phenotypes among the other tumors indicated that there are a variety of other mechanisms for such secondary events which can be investigated with this system.
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002999:Clone Cells; D003115:Colony-Stimulating Factors / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D005786:Gene Expression Regulation; D005796:Genes; D006133:Growth Substances / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D009000:Monocytes / Q000502:physiology*; D009374:Neoplasms, Experimental / Q000209:etiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000235:genetics; D011995:Recombination, Genetic
chemical_list: D003115:Colony-Stimulating Factors; D004273:DNA, Neoplasm; D006133:Growth Substances; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger