RT Book, Section A1 Chabner, Bruce A. A2 Chabner, Bruce A. A2 Longo, Dan L. SR Print(0) ID 1127646605 T1 Differentiating Agents T2 Harrison's Manual of Oncology, 2e YR 2016 FD 2016 PB McGraw-Hill Education PP New York, NY SN 9780071793254 LK hemonc.mhmedical.com/content.aspx?aid=1127646605 RD 2024/03/29 AB An obvious feature of malignant cells is their failure to differentiate, and to acquire the histologic, biochemical, and functional features of the mature cells of the tissue from which they arise. Thus, leukemia cells resemble in appearance, surface markers, and molecular profile the more primitive normal progenitors of the myeloid or lymphoid series. Indeed it has been possible to isolate a small fraction of continuously self-renewing cells (called tumor stem cells) from frankly malignant tissues. These tumor cells are able to reproduce multiple differentiated cell lineages when appropriately stimulated by "differentiating" agents such as 5-azacytidine (see Chapter 1) or retinoids. The progression from mature cell phenotype to an undifferentiated malignancy is recapitulated in serial observations of chronic myelogenous leukemia and in experimental models of malignant transformation.