You are here: MEDICA Portal. MEDICA Magazine. Topic of the Month. Volume archives. Our Topics in 2010. December 2010: The Immune System. Cancer.
Incitement to suicide
Zytostatika können in entarteten Zellen
das Selbstmordprogramm anschalten
Undetected, even smaller breakdowns can turn into a disaster. For this not to happen, immune cells in our body are constantly walking the beat to detect abnormalities. If they discover a cell whose operating system is not working correctly, the patrolling immune cells activate their suicide program – and the defective cell kills itself. An ingenious elimination mechanism.
On the surface of our somatic cells are so-called death receptors. If a cell is supposed to be eliminated, the defense cells spill specific signal substances, which fit like a key into the lock of the death receptors. After this, a chain reaction is launched inside the cell, which activates the genetic suicide program.
The programmed suicide or apoptosis doesn’t just play an important role during the elimination of defective cells – healthy cells also occasionally have to die. This is the case in tissue, where new cells are being constantly produced at a high rate. One example is the hematopoietic cell renewal system. Here the regulated cell death ensures that cell density remains approximately constant.
Cancer cells slide through
Unlike this desired, balanced cell renewal, during canceration cell proliferation is getting completely out of control. Genetic mutations which lead to such misdirected cells are no rarity, but rather a common phenomenon. It is a very essential function of our immune system to promptly eliminate such individual abnormal cells – and in most cases it succeeds.
But abnormal cells are sophisticated. Many of them have changed to the point where they are not vulnerable at their Achilles heel anymore: through several tricks, cancer cells can prevent the suicide program from being activated. Some cancer cells for example are missing death receptors. And so they cleverly slip through the files of defense cells and can propagate unchallenged.
Research has shifted into high gear
For a long time it was believed that cancer drugs are effective by poisoning vital metabolic processes in cancer cells. But this by itself doesn’t account for the therapeutic impact: by now we know that cytostatic drugs can activate the suicide program in abnormal cells. Resistance to therapy – we also know this today – is often due to the ingenious tricks, with which cancer cells escape incitement to suicide.
Currently drug research has shifted into high gear with the goal of developing highly specific drugs that can disable the anti-apoptotic tricks of abnormal cells. In this regard, green tea and the skin of red grapes contain interesting active ingredients. Betulinic acid, an ingredient of the birch bark, can also sensitize cancer cells in a way so the genetic suicide program works again.
Professor Klaus-Michael Debatin, currently the Medical Director of the University Medical Center Ulm, Department of Pediatrics, lead the way in assisting to decode apoptosis. Currently Debatin plans a first clinical trial with a pharmacological optimized Betulinic acid derivative on patients with malignant glioma, brain tumor, which counts among the most malignant cancers. He hopes that the intensive fundamental research of the past ten years in the field of apoptosis makes it possible in the future, to offer individually tailored cancer treatments with the help of molecular methods.
(Translated by Elena O'Meara)