Apoptosis and Necrosis - Two Paths to Eliminating Cancer Cells

Friday, November 04, 2005

Most normal cells in the body have a defined lifespan. If you put them in a petri dish and manage to grow them, a cell line will divide a certain number of times and eventually die off. Another instance when cells die off is when something goes wrong with the cellular machinery. This error triggers a process of orderly cell death called apoptosis. In apoptosis the cell quietly shuts down, breaks into smaller pieces and is engulfed by white blood cells.

In many cancers including mesothelioma, there is a problem with apoptosis. A genetic defect causes the cells to grow out of control but the natural process of programmed cell death is turned off.

Another kind of cell death is called necrosis. This is the unexpected death of a cell from a toxin or an environmental cause. Because the cell does not shut down in an orderly fashion, the cell does not have time to package and get rid of extremely powerful enzymes and chemicals like peroxides. As the cell bursts open these intracellular elements damage surrounding cells causing and inflammatory response where large numbers of white blood cells move into the area to stem the damage. This very messy and sometimes dangerous process is basically what is happening with radiation and chemotherapy. Fast dividing cells are more susceptible to these therapies and are destroyed by necrosis. Some of the negative side effects of radiation and chemotherapy are caused by the inflammatory response that is triggered.

The best way to deal with cancerous cells would be to turn apoptosis back on in the cancer cell. The cancer cell would recognize that it is defective and initiate programmed cell death. Drugs like Onconase attempt to do just that. As our understanding of the underlying genetics of meso improves hopefully we will get a better handle on apoptosis and use it to combat the disease.