Cancer Research in Switzerland - Krebsliga Schweiz

cooperation with dermatologists and pathologists at
University Hospital Zurich, we made the important
discovery that the number of these cells in the patient’s
tumour was connected with the course of the
disease: The higher the number of cells with characteristics
of neural crest stem cells that are found in a
biopsy, the greater the probability of metastasis and
of the patient dying of cancer.
Inhibition of melanoma stem cells
Thanks to our experience in the area of neural crest
development, we were able to more precisely characterize
these tumour cells and test their cancer­producing
effect in animal models. In these experiments,
the cells prove to be actual melanoma stem
cells that can multiply arbitrarily and are responsible
for tumour growth in animal models. This finding is
not undisputed, as no cells having stem cell characteristics
could be found in melanoma in research
work conducted in the United States. This also shows
that research in this area is still in its beginnings. In
particular, researchers need to develop standard
protocols for how cancer cells are removed from the
tumour and then cultivated. For example, we were
able to demonstrate melanoma stem cells only using
refined methods by which the tumour tissue was
treated as carefully as possible. In addition, we
discovered that melanoma stem cells have a special
ability to evade detection by the immune system.
Finally, this research work can create a foundation
for the development of new strategies in cancer therapy.
For example, target structures for therapies
could be identified by comparing normal stem cells
and cancer stem cells. Based on this, genetic characteristics
and cellular properties of cancer stem cells
are determined. The knowledge of stem cell­specific
biomarkers and growth factors could aid the discovery
of pharmaceutically active substances that inhibit
cancer stem cell development. By using this
approach, in cooperation with the Institute of Pharmaceutical
Sciences at ETH Zurich, we have already
identified chemical substances that suppress the
division of melanoma stem cells and, in animal models
at least, counteract with tumour formation. However,
the exact mechanisms of how these substances
work must still be investigated, and it will take some
time and more research work before their clinical
application with patients can be tested. However, it
is definitely conceivable that knowledge gained via
melanoma stem cells could considerably improve the
therapy approaches available today.
To achieve these goals, there are still many questions
that must be clarified. Do tumour stem cells derive
from normal stem cells? Do they form tumour tissue
“hierarchically”, as in the healthy organ? Or is the
opposite developmental direction in the tumour also
possible, so that tumour cells without stem cell
characteristics can again become tumour stem cells
under certain conditions? That kind of neoplasm
of cancer stem cells could take place in the course of
metastasis or under the influence of the immune system,
for example. If that were so, the aim of therapy
would perhaps not consist so much in eliminating a
certain (stem) cell population in the tumour. Instead,
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