• Question: how does cancer start

    Asked by n1c0le123 to Alex on 20 Jun 2011.
    • Photo: Alex Davenport

      Alex Davenport answered on 20 Jun 2011:

      Cancerous cells occur all the time in your body. You probably have some right now! In most cases your immune system detects this and kills them. However in some cases, the immune system doesn’t detect this and so the cancer can continue to grow and thats when it become a problem. Cancerous cells have to evolve and mutate to stay ahead of the immune system, and when you get a cancer what your seeing is the one cell out of potentially billions that managed to evade the immune system thorugh a series of advantagious (to the cell) mutations.

Comments

  • Photo: Jess

    Jess commented on :

    Just stumbled on this .. and thought I might add alittle on the events inside the cells

    Some of the main reasons described by D. Hanahan and R.A. Weinberg about why cells become cancerous is because:
    1. the cell’s growth signals have gone out of control
    The cancer cells are able to make their own growth factors (proteins that send signals to the cell to divide and grow) rather than relying growth factors made from other cells. Or the cells have mutations in the genes that will allow it to keep growing!

    2. Not responding to growth stopping signals
    Normal cells can stop growing when they receive signals from outside the cell tells them to stop. However, cancer cells do not listen to these signals and do quite the opposite, which is to keep growing indefinitely!!! rebellious cells!!

    3. Fighting cell death signals
    Usually, a damaged normal cell will try to fix itself unless the damage is so great that it is impossible to do so then the cell will receive signals to undergo apoptosis (a fancy word but it basically mean cell death). It is normally damage in the DNA (genetic codes).
    Cancer cells will not listen to these cell death signals and keep growing with the damaged DNA.

    4. Unlimited potential to divide
    Remember I mentioned those things called Telomeres at the end of chromosomes in cell ageing. Well they have a big role in cancer cells too! Normal cells will stop dividing after they have reached their own Hayflick limit (number of cell division) because telomeres get shorter and shorter after each round of DNA replication until no more telomeres are protecting the chromosome anymore then it will die. Cancer cells can produce its own telomere making enzymes (telomerase) and tell them to keep adding telomeres on to the end of chromosomes after each DNA replication so the cell never have to die!!

    People in my lab are making drugs to target the enzyme, telomerase!

    5. Making new blood vessels
    Like normal cells, cancer cells need food and oxygen delivered to them via the blood vessels in order to keep growing.
    But unlike normal cells, cancer cells can send signals in its surrounding to stimulate the growth of new blood vessels so they can have food delivered straight to them!! (So like when you order a pizza from dominos- they will deliver the pizza and garlic bread straight to your door!!)

    6. Moving around the body
    Most normal cells will stay in one place in the body until they die and again, cancer cells love doing what they are not supposed to!
    So cancer cells have their own mutated enzymes (imagine the enzymes are like a pair of scissors, they are able to cut around the cancer cells from neighboring cells so they are free to move around).
    As I mentioned in point 5, the cancer cells already have their own blood vessels so these cancer cells that are free to move around can travel in the blood vessels to pretty much anywhere else in the body and live there (almost like an enormous water slide!!)
    At this late stage, this is when the cancer cells are at its most dangerous and can kill people ):