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A Cancer Gene Keeps Itself in Check
A breast cancer cell (yellow) under
the electron microscope.Scientists
describe a feedback mechanism that
regulates the activity of the Myc
cancer gene;© Kristian Pfaller/
University of Würzburg
The point is not to put out the fire in the house but to keep it in check – to make it burn in the fireplace and nowhere else. To make this balancing act in the body work, the first point is to understand the principles of cell growth regulation.
Here Theresia Kress from the working group of Professor Martin Eilers at the Biozentrum of the University of Würzburg has made an important discovery: In cooperation with an international team, she has found a feedback mechanism that adjusts the activity of the growth-inducing Myc “cancer gene” at the right level. This mechanism may play an important role in the development of colon cancer.
The Myc gene produces the so-called Myc transcription factor, which regulates a multitude of other genes and thus drives the growth and reproduction of cells. When the Myc gene gets out of control, it allows cell growth to run riot – this is why it is referred to as “cancer gene”.
But how does a cell notice whether there is enough Myc? Eilers and his team had their sights on a specific type of enzyme, the so-called protein kinases, as a possible signal transmitter. So Kress deactivated all these kinases one by one and examined what happened then.
The strategy had success: The researchers found out that it is the protein kinase MK5 that inhibits the activity of Myc, and thus keeps cell growth in check. They also discovered how Myc inhibition works in detail, and which other genes and molecules are involved.
But most important of all, Kress and Eilers could demonstrate that the protein kinase is in turn activated by Myc. So the feedback comes full circle: the higher the level of growth-inducing Myc in the cell, the higher the production of the inhibitor – in this way Myc keeps itself in check, and the rate of cell growth remains in balance.
A further examination revealed that it is exactly this feedback mechanism which is blocked out in colon cancer cells. Now this could be one of the causes for the development of cancer, and thus a possible starting point for therapy.
The work was in the context of the Growthstop research project, which is sponsored by the European Union and coordinated by the Innsbruck-based project management firm CEMIT.
MEDICA.de; Source: Julius-Maximilians-Universität Würzburg