Why dread a bump on the head?June 2012
Lesson 5: What happens to neurons after TBI?
Apoptosis and Cancer
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Why dread a bump on the head?June 2012
Lesson 5: What happens to neurons after TBI?
Whenyou hear apoptosis summarized as “programmed cell death,” you may have assumed that the process always results in negative consequences. However, there are several examples of how apoptosis helps maintain a stable balance, in healthy tissues by regulating the normal amount of cells.If apoptosis stops, the result can be uncontrolled tissue growth known as cancer.
Getting rid of cells can be a good thing.If a cell is damaged or old, it can be beneficial for the cell to be replaced with a new cell.Recall that parts of the cell cycle include making a copy of the cell’s DNA and dividing it, along with the organelles, into two new daughter cells.Yet if new cells were continuously made without eliminating old cells, a tissue could grow so big that it becomes detrimental to itself or surrounding tissues.Apoptosis is the mechanism that provides a controlled way to get rid of cells.
Imagine a hypothetical population of 100 body cells.If all of the cells complete the cell cycle one time, the total population would double, that is become 200 cells.If all of those 200 cells complete the cell cycle one time, the total population would be 400 cells.You can see how the total number of cells could dramatically increase quickly if no cells were eliminated.Cells are eliminated systematically in normal tissues via apoptosis.
Apoptosis is initiated by a series of events that occur through complex interactions between specific molecules within the cell.The signal to start apoptosis can come from inside the cell or from outside the cell.Once the signal is received the genes for apoptosis are activated and apoptosis proceeds with “chromatin condensation, nuclear fragmentation, cell shrinkage and membrane blebbing” (Yang, 2005, p. 2).
Cancer results not only from the uncontrolled production of new cells, but also from the lack of elimination of cells via apoptosis. An important gene involved in inducing the apoptotic pathway called p53.The p53 gene is called a tumor suppressor gene because it increases the signals that promote apoptosis, and it reduces the signals stopping apoptosis.Normal p53 fights tumors by killing the excess cells via apoptosis.It should not be surprising to learn that in abnormal cells that result in the growth of tumors in humans, genetic mutations are often found in p53 (Yang, 2005, p. 11).As a consequence of this mutation, apoptosis does not occur, and cancer cells proliferate.
The knowledge that some cancers result from a lack of apoptosis has provided researchers with a strategy for fighting cancer.The use of drugs that eliminate the mechanism by which cancer cells have become resistant to apoptosis can be used in combination with other treatments such as chemotherapy and radiation to control the unchecked proliferation of cells that leads to cancerous tumors (University of Illinois at Chicago, 2012).
References
National Cancer Institute.(2005).Understanding cancer and related topics [PowerPoint document].Retrieved from National Cancer Institute at the National Institutes of Health Understanding Cancer Series Web Site:
Yang, L. (2005).Disfunction of the apoptotic pathway in cancer cells.In M. Sluyser (Ed.), Application of Apoptosis to Cancer Treatment (pp. 1-28).The Netherlands: Springer.
University of Illinois at Chicago (2012, March 1). Molecule's role in cancer suggests new combination therapy. ScienceDaily. Retrieved June 27, 2012, from
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