Naked Science Forum
Life Sciences => Cells, Microbes & Viruses => Topic started by: Biology Guy on 29/03/2007 13:55:54
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How are cancer cells able to multiply endlessly without dying. Do they mutate and prevent a certain molecule from activating the apoptosis (programmed cell death) pathway or do they shut off the mitochondria (where apoptosis molecules are held) completely? Or is there some other way the cancer cell does this?
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I'm not quite sure, but as far as I know, there are two main reasons why they multiply endlessly without dying.
1.they avoid apoptosis & 2.they avoid being killed by the immune-system.
Now to apoptosis: actually the programmed cell death can be activated on different pathways.
(and i think we still didn't fully understand all in apoptosis pathway)
Here is "simplified" poster of the pathway: http://www.emdbiosciences.com/sharedimages/calbiochem/pathway/apoptosis_pathway_main_larg.jpg
(now I'm really not sure, so correct me if I'm wrong)
The most important enzyme-family in apoptosis is caspase. (These enzymes trigger cell death.)
Now there are mainly two different ways to activate caspase. 1. Extracellular signals activate caspase. 2. mitochondrias release Cytochrom C into the cytosol. Cyt C can activate caspase indirectly, but it can also enhance an extracellular apoptosis signal.
Cancer cells neither react to extracellular apoptosis signals (for example they simply get rid off the receptors for the apoptosis signal) nor react to Cyt C. (Apparently Cyt C still need another mitochondrial protein (Smac) to activate caspase, and cancer cell mitos do not release Smac)
(I don't think, that they shut down their mitochondrias, since they still need them to gain ATP.)
Hmm, I hope I could at least help a bit.....
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That has helped me a lot, thank you.