Speaker Name(s): John E. Dick, Ph.D. Description: John E. Dick, Ph.D., Division of Cell and Molecular Biology, University Health Network, and Dept. of Molecular Genetics and Microbiology, U of T.
Two fundamental problems in cancer research are identification of the normal cell within which cancer begins and identification of which cell type in the tumor is capable of sustaining the growth of that cancer. There is overwhelming evidence that virtually all cancers begin in a single cell (that is, they are clonal). However what is becoming clear is that not every one of the cancer cells that make up the tumor mass is equally the same. There is now evidence that for most cancers, only rare cells within the cancer are responsible for keeping the cancer growing. These were first identified in blood cancers (leukemia). We called these cells leukemic stem cells (LSC). Most cells in a leukemia grow rapidly, but the LSC grow very slowly, but are still very powerful as they keep making more of the fast growing leukemia cells. Because they grow so slowly they are resistant to most kinds of chemotherapy that are designed to kill the fast growing cells. This can explain why leukemia can come back after treatment. So to truly get rid of the leu¬kemia, you have to find ways of eliminating the LSC. It turns out that solid tumors also have these rare so called Cancer Stem Cells (CSC) and there is much current work going on to understand the properties of these CSC and how these cells might escape therapy.