A Prospective Analysis of Human Leukemogenesis

Abstract

Decades of lack of progress in treating many fatal malignancies of the blood-forming system is commanding interest in new approaches. Targeting early events in the leukemogenic process has long been recognized as likely to offer the information required for these diseases. Analysis of the representation of different mutations in the leukemic cells from individual patients offers a retrospective method to infer their sequence of acquisition and associated subclonal dynamics. An alternative, prospective approach is to exploit strategies for recreating human leukemia de novo using defined genetic methods. This concept is not new, but has been historically difficult to realize. A brief review of our experience in generating insights into the properties and regulation of primitive normal human hematopoietic cells serves as a reminder of how this has enabled our recent advances in developing this approach using both primary sources of chronic myeloid leukemic cells and normal cord blood cells as targets.

Dr. Eaves holds a BA in Biology and Chemistry and a MSc in Genetics from Queen’s University, Kingston, Ontario, and a PhD in Immunology from the University of Manchester, UK. Following post-doctoral training in experimental hematology at the Ontario Cancer Institute under Dr. James Till in collaboration with Dr. Ernest McCulloch, she joined the faculty of the BC Cancer Agency and the University of British Columbia in 1973. In 1981, she and her husband co-founded the Terry Fox Laboratory at the BC Cancer Agency. Over the last four decades, Dr. Eaves has developed an internationally recognized research program that continues to address fundamental questions in normal and cancer stem cell biology. Her contributions have included the development and use of quantitative methods to molecularly and biologically characterize rare, functionally defined cells of the blood-forming system, the mammary gland, leukemia, and breast cancer that have become gold standards in these disciplines. More recently, her group has pioneered the creation of several models of de novo leukemia and breast cancer starting from primary sources of human cells. She has published more than 500 papers and has a long track record as a scientific leader and devoted mentor of more than 100 postgraduate trainees at all levels in multiple disciplines. She has also been an energetic lifelong contributor to the development of science policy and management in Canada and abroad, and maintains an active role in editing and reviewing scientific publications. She has received many prestigious national and international awards for her numerous and diverse accomplishments, including election as a Fellow of the Royal Societies of Canada and Edinburgh, the Noble Prize for Cancer Research, the Metcalf Lecture and Prize from the International Society of Hematology, and the Stratton Lifetime Achievement Award and Donall Thomas Lecture and Award from the American Society of Hematology.

Figure 1

Schematic Visualization of the Hierarchical Organization of Normal Human Hematopoietic Progenitor Cell Types This schema is based on the number, type, and duration of time over which different progenitor cell types produce mature blood cells when optimally stimulated. Cell surface expression of CD34 generally separates all of these cells (2% of all nucleated bone marrow cells) from their CD34-negative, morphologically recognizable maturing progeny (98% of all nucleated bone marrow cells). CD38 then further subdivides the CD34⁺ subset as shown. CRUs refers to competitive repopulating units (in immunodeficient mice), LTC-ICs to long-term culture initiating cells (in stromal cell-containing cultures), and CFCs to colony-forming cells or short-term clonogenic progenitors.

Figure 2

Schematic Visualization of the Different Types of Hematopoietic Cells Present in Patients with Chronic-Phase Chronic Myeloid Leukemia This diagram shows the increasing representation of CP-CML elements (shown in red) compared with their normal (Ph/BCR-ABL-negative) counterparts (shown in white) in the same samples, together with the generally observed stage-dependent, increased cycling activity of CP-CML short-term clonogenic progenitors. Also shown in the right panel is the much poorer self-renewal behavior of the CP-CML LTC-ICs under different conditions (Eaves et al., 1998). GFs, growth factors; RBC, red blood cells; GMs, granulocytes and monocytes. Other abbreviations are as in Figure 1.

Figure 3

Effect of NUP98HOXA10 (NA10HD) Expression on Primitive CP-CML (LTC-ICs) In Vitro The top left panel shows the design of the experiments. The lower panel shows results for three different CML cell samples. The top right panel shows examples of the normal neutrophil/macrophage and erythroid differentiation of clonogenic progenitors obtained from NA10HD-transduced CP-CML LTC-ICs at the end of 6 weeks in vitro. Data are redrawn from Sloma et al. (2013). SFM, serum-free medium, Ph-, Ph-negative (i.e., normal). Other abbreviations are as in Figures 1 and 2.