p53 and Cancer
If you read any of the scientific reports on cancer you will probably come across p53. The p stands for protein and the 53 is its size. One way of working out the size of a protein is to run it on a gel, and p53 shows up at the 53 kDa (kiloDalton) size. It’s a bit like naming roads; M25 means motorway 25, which doesn’t really tell you much, but most people in London know it is the so called “ring road” that runs around London and is frequently one very large car park,
Just as a traffic jam on the M25 can cause havoc with your plan to get to Gatwick Airport, a messed up p53 can really screw up your cells. p53 is defective or mutant (i.e screwed up) in over half of all human cancers. That means a) it’s important and b) lots of researchers are trying to find ways of fixing it.
Here is the science bit, normally your p53 levels inside your cells are low. Low is good, low is normal. If you do something to your body that might damage your DNA, (for example give yourself sun burn, smoke a cigarette) then your p53 levels will go up. p53 then has to decide if the DNA damage can be fixed or if it’s a lost cause and the cell needs to be destroyed. (You have umpteen million cells, so losing a couple of damaged ones isn’t a disaster). IF the DNA damage can be fixed then p53 puts the brakes on and stops the “Cell Division Cycle” and lets it catch up with it’s repairs (a bit like getting an extension on an exam, it gives you more time to get things right). If the damage is too bad to fix p53 starts the cell destruction process called apoptosis (a-pop-toe-sis) which is also know as cell suicide. (This is a bit like your teacher throwing you out of a class and asking you not to come back)
That’s what happens in a normal situation, but I just said that p53 is messed up in over half of all human cancers, so what happens then? Well, if your cell gets DNA damage, it just keeps growing, it doesn’t stop to fix the mistakes and you get more DNA damage. The more DNA damage you get, the more likely you are to get a cancer cell that grows and spreads when it shouldn’t. So why don’t we just fix the broken p53? Lots of laboratories are trying to do that, using lots of different techniques, but at the moment, there are no p53 treatments in the clinic (that is not to say there never will be, these things are just a lot more complicated than you might think)
So next time you hear about p53 “The Guardian of the Genome” you’ll know why, everytime your DNA gets damaged, it springs into action and decides what is the best thing to do to keep you healthy.