Cells have what is called contact inhibition. This means that once they come into contact with each other (or something else), they will cease to grow (or slow growth significantly). However, this is not true of cancer cells. Indeed, it is a hallmark of such cells; they grow and grow and even layer atop each other. Contact inhibition controls cell growth and cancer is, by one general definition, uncontrolled cellular replication.
A recent study led by Vera Gorbunova of the University of Rochester has focused on the naked mole rat and why it has never been observed to develop cancer.
The findings, presented in The Proceedings of the National Academy of Sciences, show that the mole rat’s cells express a gene called p16 that makes the cells “claustrophobic,” stopping the cells’ proliferation when too many of them crowd together, cutting off runaway growth before it can start. The effect of p16 is so pronounced that when researchers mutated the cells to induce a tumor, the cells’ growth barely changed, whereas regular mouse cells became fully cancerous.
This gene is on top of another gene which contributes to restricted growth. Humans (and other animals) only have one, p27, and it gets ‘worked around’ by cancer commonly enough. Cancer in the naked mole rat is theoretically possible, but since it has to breach two barriers to uncontrolled cellular growth, it is unlikely.
As always, there is an excitement with any discovery which could contribute significantly to curbing or stopping many of the major diseases afflicting humanity, but it must be met with temper.
It’s very early to speculate about the implications, but if the effect of p16 can be simulated in humans we might have a way to halt cancer before it starts,” [says Vera Gorbunova].
Might is the key word, and I think Gorbunova’s caution is appropriate. Cancer is a bit of a devil, to say the least, and every discovery seems to lead to a more complicated understanding of how it works. We’ll see what this research turns out to really mean.