15 November 2012
Original Research Commentary
I came across an interesting article the other day: Cancer resistance in the blind mole rat is mediated by concerted necrotic cell death mechanism (1) Apparently, the blind mole rat almost never develops cancer, and is an unusually long-lived species of rodent. While mice and rats have a maximum lifespan of ~5 years, the blind mole rat can live as long as 21 years. The authors claim that in 40 years of keeping the blind mole rat in captivity at their facilities, that they have never seen a case of spontaneous cancer in the blind mole rat.
Though, I find this claim somewhat hard to believe, unless the authors have done full autopsies (a time and labor-intensive practice) on all their dead blind mole rats for the last 40 years. Regardless, the authors uncover an interesting characteristic of cells taken from the animals: after a certain amount of divisions in a row, the cells all die in a coordinated cell suicide in culture. This does not happen in human cells in culture, nor does it happen to cells from other rodent species.
So, one would predict that a developing tumor in a blind mole rat would spontaneously regress after a few rounds of rapid proliferation (which would theoretically only happen in adults in the case of a developing tumor). It seems fairly straightforward, almost too straightforward…
The authors then found that culture media (the fluid kept on top of cells kept on culture dishes) from the cells undergoing coordinated cell death could induce the same thing in younger cell cultures, making it likely that it was a factor secreted by the cells that caused this hypothetical anti-cancer response. Through several methods, the authors determined that the concentration of a factor known as Interferon-Beta (INF-B) closely mirrored this coordinated cell death, and claim this as the mechanism.
However, the authors did not report inducing this massive, coordinated cell death in response to purified INF-B, which would have been a causative experiment, not a correlation observation. There are likely thousands of factors in the media, and any one of them (or a combination of them together) could be the causative agent(s). Also, this medium containing whatever factors are responsible for this putative anti-cancer response do not have the same effect on human cells, which brings into question the translatability of this phenomenon to therapies in humans.
My verdict: I am not sure if the authors have identified the correct mechanism, but the longevity of the blind mole rat and its purported lack of cancer is a phenomenon that might yield future insights into graceful, disease free aging in another long-lived species: homo sapiens.