Junk on Cancer

The University of Michigan has put out a press release entitled:

Bits of 'junk' RNA aid master tumor-suppressor gene

With a title like that, how could I not blog the hell out of this bastard? I mean, they even put the scare quotes around "junk". Like that -- like I just did. Amazing!

The story is about three micro RNA genes (miRNAs) that interact with p53 -- the cancer gene -- and are not expressed properly in some lung cancer cells. Not only have these researchers cured cancer, Guido Bommer, the lead author, seems to think they've found the cure amidst piles of junk:

"In the 'junk' lies treasure, in terms of critical knowledge about how normal cells stifle cancer or succumb to it."

Let me tell you a little story about junk DNA, and I think Guido should also pull up a chair. You see, when a sequence of non-protein-coding DNA has a function (for example, it encodes a miRNA), it is not junk. In fact, when we say that the majority of the genome is junk, we aren't assigning the title "JUNK" to certain sequences. We're saying that there's a fraction of the genome that has absolutely no function. It's a statement of probability, not one of determination. It's impossible to say which segments are functional and which are not without doing detailed molecular studies (like the one done by Dr. Bommer and colleagues). But we can infer the fraction of the genome that is functional by comparing genome sequences from within and between species.

Thankfully, the word "junk" does not appear at all in the actual scientific paper (available here). Most misuse of the term junk DNA comes from the scientific press, but it's a shame to see an author of the paper fall prey to such sloppy use of jargon.