Constitutive expression of full-length c-Myb transforms avian cells characteristic of both the monocytic and granulocytic lineages.
Both viral Myb (v-Myb) and cellular Myb (c-Myb) are nuclear sequence-specific DNA-binding proteins that can function as transcriptional activators. v-Myb, encoded by avian myeloblastosis virus, induces acute monoblastic leukemia in chickens and transforms avian myelomonocytic cells in culture. The normal c-Myb protein is essential for hematopoietic development. Previous reports suggested that truncation of c-Myb is required for oncogenic transformation of avian myelomonocytic cells in culture. In this study, we demonstrate that constitutive expression of full-length c-Myb can transform avian myelomonocytic cells isolated from embryonic yolk sacs by using a strategy to enhance the efficiency of infection and/or expression of c-myb-containing viruses. c-Myb-transformed myelomonocytic cells display a different phenotype than cells transformed by v-MybAMV or other Myb mutants. c-Myb-transformed yolk sac cells are heterogeneous populations with characteristics of both the macrophage and granulocyte lineages. Our results demonstrate that constitutive expression of full-length c-Myb is sufficient to activate its oncogenic potential, but that the target cells for c-Myb are relatively rare and presumably quite immature.
Fu
S L
SL
Department of Pathology, Stanford University, California 94305-5324, USA.
Lipsick
J S
JS
D000818:Animals; D002455:Cell Division / Q000235:genetics; D019070:Cell Lineage; D002478:Cells, Cultured; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000235:genetics; D005347:Fibroblasts; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006098:Granulocytes / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D020626:Oncogene Proteins v-myb; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics*; D014162:Transfection / Q000379:methods; D015017:Yolk Sac / Q000166:cytology
D004268:DNA-Binding Proteins; D020626:Oncogene Proteins v-myb; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D015682:Retroviridae Proteins, Oncogenic; D015534:Trans-Activators