摘要：

The chapter discusses about the murine virus-induced leukemia (FLV) that serves as a model system for exploring the relationship between differentiation and malignancy. The cells of this virus-induced leukemia (FLC) differentiate along the erythroid pathway in vitro and, under special conditions, in vivo as well. Reports on the differentiation of tumor cells in vitro include: studies of human and murine neuroblastoma cells as well as of human leukemic cells and murine leukemic cells. The studies describe that the malignant cells possess at least some of the genetic information that controls the growth and fate of their normal counterparts. Recent studies on human acute lymphoblastic leukemia cells demonstrate the presence of terminal deoxynucleotidyl transferase, an enzyme found only in normal thymus cells, indicating that in some human leukemic cells, there is retention of certain specific genetic information of the tissue of origin. It was observed that FLC, cultured in the presence of DMSO or DMF alone or in combination with BUdR, increased numbers of budding viruses on their cell membranes. It appeared that the cells synthesizing murine leukemia Type C virus particles are not necessarily malignant, for the agents (DMSO, DMF) that stimulate differentiation, with a concomitant decrease in malignant potential of FLC, also increased the number of budding virus particles. BUdR inhibits the differentiation and, yet, also increases the number of budding viruses.

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