When it comes to wandering Methuselah's zoo in search of comparisons between species that might lead to greater understanding of human longevity - and how to increase it - the naked mole rat stands out as a prominent point of interest. It lives for something like nine times longer than some similar rodent species, and appears to have unusually resilient biochemistry for a mammal.
You might recall that different fatty acid or lipid composition in cell membranes was floated as a reason for the ninefold longevity of naked mole-rats over related rodent species. Plenty of oxidative stress in the older mole-rats, but little sign of biochemical damage resulting from it - in comparison to those other rodents long since aged to death, that is. Better, more damage-resistant building blocks down at the molecular level might be the cause.
The concept of "better membranes" has a theory of aging to go along with it: the membrane pacemaker hypothesis. Follow that link if you care to find out more.
Naked mole rats are not just very long-lived, however. They also appear to be immune to cancer. No naked mole rat has been observed to suffer from cancer, a fact that is attracting interest from the cancer research community as this species becomes more widely studied. If the biochemistry that leads to this feat can be understood, it is possible there exists an economical way to port that cancer immunity to humans.
One of a number of further lines of investigation into naked mole rats and cancer caught my eye today. It's the essence of genetic research on the frontier of the unknown: change some genes and see what happens next. In this case the researchers demonstrate that naked mole rat cells essentially fall to pieces and become non-viable when cancer-causing genes are introduced:
The naked mole-rat (NMR, Heterocephalus glaber) is a long-lived mammal in which spontaneous cancer has not been observed. In order to investigate possible mechanisms for cancer resistance in this species, we studied the properties of skin fibroblasts from the NMR following transduction with oncogenes that cause cells of other mammalian species to form malignant tumors.
NMR fibroblasts were transduced with a retrovirus encoding [the cancer-causing oncogenes]. Following transplantation of transduced cells into immunodeficient mice, cells rapidly entered crisis, as evidenced by the presence of anaphase bridges, giant cells with enlarged nuclei, multinucleated cells, and cells with large number of chromosomes or abnormal chromatin material. In contrast, similarly transduced mouse and rat fibroblasts formed tumors that grew rapidly without crisis.
Thus, rapid crisis is a response of oncogene-expressing NMR cells to growth in an in vivo environment ... The unique reaction of NMR cells to oncogene expression may form part of the cancer resistance of this species.
Give it another five years or so and we might expect to see good answers as to whether exploitable knowledge lurks behind the absence of cancer in naked mole rats.
Liang S, Mele J, Wu Y, Buffenstein R, & Hornsby PJ (2010). Resistance to experimental tumorigenesis in cells of a long-lived mammal, the naked mole-rat (Heterocephalus glaber). Aging cell PMID: 20550519