Carcinogens and Me Part I: Cancer

So what's the deal with all these "probable carcinogens"? How many times have you seen an article with a headline like "BCB causes cancer"? Given that you might be laying off the BBQ or buying a metal water bottle based on those headlines, haven't you ever wondered where they get off making claims like that? Well, to understand this, we need to get our heads around what cancer is and how it starts.

Imagine a random skin cells on your left arm. Every time you go out in the sun, these poor cells get blasted with UV light, and DNA doesn't get along well with UV light. DNA is made from four bases, A, T, G, and C (the only 4 letters in the title of the movie "GATTACA". Clever, eh?) When two 'T's are next to each other, the UV light can make them fuse together.Let's say this happens to our skin cells. Well along comes a protein trying to read the DNA, and it's not sure what to make of the mess it sees, but it definitely doesn't read two 'T's. Well now whatever protein that DNA was coding for doesn't work. Heck, maybe our mutation was in DNA that's only turned on in liver cells anyway, so we never notice. One cell doesn't do much, but the real problem comes when the cell goes to divide. If the problem isn't fixed, when the cell copies its DNA, it tries to read the fused 'T's, isn't sure what to do, so it throws in a couple random letters. The new cell's DNA looks normal, but it has some random junk in there, which it passes on when it divides again and again and again...

Now we introduce something called apoptosis, aka "programmed cell death". Normally, your cells have all sorts of controls that make sure you they don't cause you problems. If a cell encounters major programs, a protein pathway in the cell makes the cell self-destruct. Let's say a kidney cell finds itself in the liver... *¡BAM!* it kills itself. A cell's DNA gets so damaged it can hardly limp along anymore... *BAM* - apoptosis. Once we're born, most cells in our bodies really slow down how often they divide. If a cell starts dividing too fast... *BAM* - apoptosis.

But remember how DNA damage can lead to broken proteins? Let's say our little skin cell has some terrible luck. At age 7, it takes a hit in a part of DNA that makes a protein needed for apoptosis. No more self-destruct. At age 23, it picks up DNA damage that makes it lose one of three proteins that stop it from dividing so rapidly. At age 48, more DNA damage and you lose another. Age 59, one more hit to the DNA and you lose the last protein stopping the cell from dividing. The cell kicks into overdrive, but without the programmed cell death mechanism, there's nothing there to stop it. You notice some funny brown spots on your skin one day. A few years later, cells from those funny spots have migrated into your kidneys, lungs, colon, and heart, and have kept dividing until you have tumors causing you major problems.

So when did this skin cell become cancerous? Was it at age 7 when it got its first mutation? Was it age 59 when it started dividing? The bottom line is that, had you worn more sunscreen at 23, you wouldn't have cancer at 59. It's the same reason you don't see 18-year old smokers with lung cancer, it takes years to accumulate just the right cocktail of mutations. Now you might be saying to yourself, "I'm no dummy. There are 3 billion little letters of DNA in every one of my cells. What are the odds that one cell would get just the right mutations in just the right order that it would become cancerous?" Well, let's say the odds are one in a trillion. Did you know your body has an estimated 100 trillion cells?

The moral of the story is that random DNA damage is one cause of cancer. So unless you're Spider-Man or the Fantastic Four, it's probably best to stay away from things that play games with your DNA. Now I know what you're thinking, "How do I know what messes up my DNA?" Well... tune in next time!