Q&A: Why do researchers use mice for experiments?

Q: Why do cancer researchers use mice for their experiments?

A: The reason we use mice is because they are (in order of importance) 1) much easier to do experiments on mice than with humans (Imagine: "You want to do what with my spleen?"), 2) closely related in their genome/anatomy/biology to humans (known as homology) - so the theory is "if it works in mice, it probably works the same way in humans", 3) inbred so that the genetic differences between individual mice are minor (its important to know the reason you see an effect is because of your experiment, not a a difference in the mouse itself), 4) small and we can fit multiple mice in a cage for efficiency, and 5) we can acquire them at relatively easily.

When we experimentally induce cancer in mice we call them "models" because they represent (although not exactly) a living system that we can use to find out some information about the disease. Much of the research going on now in the cancer field is to figure out what genes are altered when cancer forms and then to make those same DNA-level changes in mice (known as a transgenic mouse model). This strategy has had some moderately good success in generating mouse models of pancreatic, lung, colon, breast, and some hematologic (i.e. blood-related) cancers.

Cons:
- It goes without saying that there are still huge differences between mice and humans. This includes genetics, lifespan, lifestyle, etc. Not everything that works in mice works in humans.
- If left on their own, humans and mice develop a different spectrum of cancers. Humans most often develop solid tumors (prostate, colon, breast, pancreas, etc), whereas mice develop myeloid and lymphoid tumors (leukemias and lymphomas). No one is quite sure why this happens, but some people believe it has much to do with the length of telomeres (protective"caps" on the ends of chromosomes).
- The development of cancer is rarely as straightforward as a single/handful of genetic changes we create in the lab. Remember, people usually get cancer in the latter part of their lives - they have lived long enough that they have accumulated many mutations that normally are bearable until the straw that breaks the camel's back and cancer develops (smoking speeds up this process). Therefore, its very difficult to recreate ALL of these genetic events to get and EXACT recapitulation of what goes on in real life.

I'll try to find a good review article and post it on here when I get a chance.