Cancer cells are notorious for their ability to exploit the normal processes of the cell for their survival. Weizmann Institute scientists recently identified one of the sophisticated tricks they employ: disrupting one of the important "security" mechanisms of living cells.
Cancer cells are notorious for their ability to exploit the normal processes of the cell for their survival. Weizmann Institute scientists recently identified one of the sophisticated tricks they employ: disrupting one of the important "security" mechanisms of living cells.
Understanding the way in which cancer cells disrupt this mechanism may lead to the development of new ways to treat cancer patients, to increasing the effectiveness of existing drugs, and to adapting the treatment plan to the specific tumors.
This is the endocytosis mechanism, which allows extracellular substances to enter the cell.
In the first stage of the operation of this mechanism, a kind of alcove in the cell membrane is created - as a result of contact with a foreign substance. The niche becomes deeper, then closes on itself, "swallows" the foreign material, detaches from the cell membrane - which completes itself - and creates a sort of vesicle that moves in the interior of the cell. This is how different molecules (foreign or self) can move from the surface of the cell, into it.
Most of the substances introduced into the cell in this way are eventually broken down by the intracellular microscopic organelle called a lysosome. Prof. Yosef Yordan and (then) research student Dr. Yaron Mosenzon from the Department of Biological Control at the Weizmann Institute of Science, along with other scientists at the institute, As well as with Prof. Gideon Ravavi from the Sheba Medical Center, Prof. Aryeh Edmon from the Technion, and Prof. Fernando Schmitt from the University of Porto, Portugal, they believe that the malignant tumor disrupts and exploits endocytosis in the various stages of cancer development.
For example, when the inner layer lining the lung cavity and the milk ducts in the breast is regenerated, endocytosis regularly removes the receptors for growth factors from the cell membrane. These receptors are pumped into the vesicles and destroyed within the lysosome. In this way, the continuous stimulation created by growth factors that reach the cell from the outside is avoided, and excessive growth of tissues (which may lead to the development of cancer) is avoided. If the endocytosis does not work efficiently enough, the receptors on the cell membrane continue to contact tumor factors, and convey their "instructions" to the cells, which continue to grow without control - a process that supports the development of cancer in the lung or breast.
On the other hand, if the endocytosis mechanism is too efficient and active, it may engulf and damage the "glue" molecules that hold the cells together, preventing them from proliferating too much. In other words, overactivity, as well as underactivity of this mechanism can cause the development of cancer.
In the study, described in an article published by the scientists in the scientific journal Developmental Cell, they showed a new component that controls endocytosis in humans. The new ingredient is a protein called Lst2, and it helps to absorb and neutralize receptors for growth factors. When there is a lack of this protein, the receptors do not complete the endocytosis and continue to operate - a process that may lead to the development of cancer. A better understanding of the mechanism of endocytosis may promote the development of new drugs that will block the development of cancer at different stages. Also, it may help improve the penetration of several existing drugs into cancer cells, thereby significantly reducing the resistance of cancer cells to treatments
chemotherapies.
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At first it sounded good when talking about overactivity causing cancer, but when they added that underactivity also causes cancer...here it is already clear that the drug will take many more years to reach the market!!
Well done.