Slanted Science

Hairless, buck-toothed, visually repulsive to most humans, and living their lives in darkened burrows away from the rest of the world, these creatures are advancing scientific knowledge.

But enough about computer programmers, let’s introduce the star of this story: the naked mole rat. These creatures appear to be completely resistant to spontaneous cancers, of the kinds which all other animals succumb to (including, despite the urban myth, sharks). Scientists now believe they have discovered the reason for this immunity to tumorigenesis: a second layer of molecular protection against abnormal cell cycle progression.

To understand the mechanism scientists claim is behind this tumor resistance, let’s first look at an important difference in behavior between normal and cancer cells.

It has long been possible to grow cells – both normal and cancerous – in laboratories around the world. It’s a fairly simple procedure: take a small piece of tissue, split it into single cells using special enzymes, add a liquid containing essential nutrients such as proteins and salts, and spread the mixture onto plastic Petri dishes. Kept at 37 degrees Celsius, these cells will divide and spread across the plate.

The difference is this: normal cells, once they have filled the whole of the dish’s growing surface, will stop dividing: this is called “contact inhibition“. Cancer cells, however, have lost this control over growth: they will fill the surface, then just go on dividing, forming multiple layers of cells for as long as they are supplied with nutrients. Just as happens in a cancer growing in the body, the tumor cells fail to recognize or respond to signals telling them they should stop dividing.

The system most species use for stopping cell division when contact inhibited is a gene called p27. Naked mole rats use this gene in the same way as other species, but new research shows they, uniquely, have a backup mechanism. Their cells’ growth is also stalled by activation of a gene called p16Ink4a, which acts at an earlier stage in the inhibitory process.

So, these rats have double the protection against cancer other species have. And that has scientists salivating, as it hints at new avenues for anti-cancer therapies.

Don’t Hold Your Breath, But This May Lead To: drugs or gene therapies which are able to activate the same cancer-suppressive pathway as p16Ink4a in human tumor cells, causing them to “realize” that they are growing inappropriately and thus shut themselves down.