What Causes Cancer Cells To Continue To Undergo Cell Division?
There are many checks and balances that must be broken for a cell to become cancerous. On the basic level, it comes down to mutations. While most mutations do nothing, genes can either become more or less active when a mutation occurs. It always involves more than one event. In most of the cancers we’ve looked at in detail, there are at least 3 separate events that occurred to lead to cancer. In order to become cancerous, a cell must achieve the following:
1) Breakdown of DNA repair pathways
2) Loss of ability to enter apoptosis (programmed cell death if something’s wrong)
3) Deregulation of pathways that cause cell proliferation
4) Breakdown of checkpoints in the cell cycle
5) Activation of telemerase, which stabilizes DNA when large amounts of division is occuring
6) Activation of angiogenisis, or bringing in blood vessels to supply the tumor
Typically, what defines a cell as being cancerous is that its growth is unregulated. What causes this is usually a series of mutations in an individual cell that damage the DNA controlling the regulation of cell growth. This can result from oxidation by free radicals, radiation, or carcinogenic chemicals. Also aiding this process are mutations that damage the cell’s natural repair mechanisms, that when compromised, allow further mutations to accumulate, and eventually one of these can occur in a gene for cell regulation that triggers the unregulated cell growth known as cancer.
Well, a lot of times cancer cells probably don’t. The fact is there are probably several hundreds of cancer cells that form and die out as a single cell before one unfortunately gets the right (or wrong, depending on your perspective) sequence and goes nuts. You could try arguing against that but the fact is that anything that causes cancer isn’t chemically programmed to alter the reproduction gene in a set way to make it reproduce uncontrollably. Radiation, for example, just hits a random thing, and if it happens to be a cell, it screws up the contents quite a bit. The odds of it hitting the nucleus of that cell are already very very small, and the odds of it hitting the gene controlling reproduction are astronomical, and the odds of it hitting it in a way to cause cancer are only balanced by the sheer number of rogue particles (radiation) and the sheer number of cells.
In summation:
Not all cells that are messed up do turn right into a malignant cancer cell, there’s just so many that one of them eventually will.