Dr. Weeks’ Comment: Irving Weissman was the scientist who introduced to me the bewilderingly elegant connect of the stem cell which has inspired, in 1987, a certain poem of reconciliation. Now he takes his focus on cancer stem cells to Stanford as director of the Ludwig Center focusing on cancer STEM cells. CD47 a “don’t eat me signal” and thus we are closer to focusing on the real cancer threat – not the caner TUMOR cells, but the actual lethal cancer STEM cells.
My laboratory was first to identify and isolate the blood-forming stem cell [HSC] from mice, and has defined, by lineage analysis, the stages of development between the stem cells and mature progeny. My laboratories have also discovered the human HSC, a human brain-forming stem cell population, mouse skeletal muscle stem cells, and an osteochondral stem cell in mice. I have worked in cancer research since 1977, and more recently have concentrated on cancer stem-cell biology. In recent years, my work has included studying the potential of CD47 as a cancer therapeutic, and identifying cancer stem cells from a variety of blood and solid cancers. My colleagues and I have found that CD47, a “don’t-eat-me” signal, is highly expressed beginning in the latter stages of progression of cancer stem cells from the benign to the highly malignant state, and this counteracts “eat me” signals on preneoplastic and highly malignant cancer cells, presumably as part of the evolution of cancer clones driven by self-renewing subsets of cells in the cancer. This research brings into focus the primary role of phagocytic cells such as macrophages of the innate immune system, in tumor surveillance.