Is lineage decision-making restricted during tumoral reprograming of haematopoietic stem cells?

// Geoffrey Brown 1, * , Isidro Sanchez-Garcia 2, 3, * 1 School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK 2 Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus M. de Unamuno s/n, Salamanca, Spain 3 Institute of Biomedical Research of Salamanca (IBSAL), Salamanca, Spain * These authors have contributed equally to this work Correspondence to: Geoffrey Brown, e-mail: G.BROWN@bham.ac.uk Isidro Sanchez-Garcia, e-mail: isg@usal.es Keywords: haematopoiesis, leukemia Received: September 24, 2015 Accepted: September 29, 2015 Published: October 19, 2015 ABSTRACT Within the past years there have been substantial changes to our understanding of haematopoiesis and cells that initiate and sustain leukemia. Recent studies have revealed that developing haematopoietic stem and progenitor cells are much more heterogeneous and versatile than has been previously thought. This versatility includes cells using more than one route to a fate and cells having progressed some way towards a cell type retaining other lineage options as clandestine. These notions impact substantially on our understanding of the origin and nature of leukemia. An important question is whether leukemia stem cells are as versatile as their cell of origin as an abundance of cells belonging to a lineage is often a feature of overt leukemia. In this regard, we examine the coming of age of the “leukemia stem cell” theory and the notion that leukemia, like normal haematopoiesis, is a hierarchically organized tissue. We examine evidence to support the notion that whilst cells that initiate leukemia have multi-lineage potential, leukemia stem cells are reprogrammed by further oncogenic insults to restrict their lineage decision-making. Accordingly, evolution of a sub-clone of lineage-restricted malignant cells is a key feature of overt leukemia.