There is an interesting update on cancer stem cells in Science. They write:
THE CANCER STEM CELL model emerged in the mid-1990s,
when stem cell biologist John Dick of the University of Toronto reported
that his team had
isolated rare cells in the blood of people with
leukemia that seemed to play a key role in the cancer. Although such
patients'
blood teems with aberrant white blood cells, only a
few of them were capable of growing into a new leukemia when injected
into mice. Those cells appeared to be misguided
versions of the normal adult blood stem cells that differentiate into
mature
blood cells. Like normal stem cells, the cancer
stem cells carried distinctive surface proteins and were self-renewing:
They
could divide to produce both a regular cancer cell
and a new stem cell.
Now many researchers have examine the stem cell model and there are reasons for its validity. We have argued for Prostate Cancer and one suspects for hematologic cancers such as MDS. The article focuses on Weinberg at MIT and his new company where the authors state:
Verastem's strategy is to screen approved drugs and other chemicals for
their ability to block focal adhesion kinase (FAK),
an enzyme that helps tumor cells stick to each
other and also helps cancer stem cells survive. In the body, Weinberg
believes,
blocking FAK kills cancer stem cells directly and
also makes it harder for these rare cells within a primary tumor to
travel
through the bloodstream and seed metastases.
It should be interesting to see how this develops. Perhaps our understanding of the stem cell is not mature enough. It has also been argued that the stem cell uses exosomes to cause growth in other cells. There is still a great deal to understand.