The naked mole rat is a quirky little creature. These mouse-size rodents may be curious-looking, but they are fast becoming the rising star of cancer and ageing research. Their unusual lifestyle alone makes them interesting – unlike any other known mammal, mole rats are eusocial. They live in large underground colonies, forming a social structure more akin to a hive of bees than any rodent species. The colony centres around a single female, known as a queen, who mates with a handful of fertile males. The rest of the colony, which can consist of over 80 individuals, are infertile workers.
The scientific interest in naked mole rats stems from a number of intriguing observations; firstly, the naked mole rat can live for up to 30 years, around ten times longer than a mouse or rat. In fact, relative to body size, if humans were to live as long as these little guys it wouldn’t be uncommon for us to reach our 600th birthday! Equally fascinating is the fact that these animals never appear to suffer from cancer. Long term studies of naked mole rat colonies have consistently failed to find any incidence of naturally occurring tumours in these lucky rodents.
But there’s more than luck involved in this process. Research suggests that a specific adaptation, which originally evolved to make these rodents more manoeuvrable in tight spaces, also gives naked mole rat cells some serious personal space issues. Their cells never divide to the point of overcrowding (a process necessary for tumour development). This gifts the mole rat with resistance to cancer.
But how is this possible?
Researchers from the University of Rochester in New York have found that mole rat cells make a unique ‘gloopy’ polysaccharide known as high-molecular-mass hyaluronan (HMM-HA) which is released from specialised cells called fibroblasts. This substance is similar but much larger than human, mouse or guinea pigs (one of the mole rat’s closest relatives) hyaluronan. When hyaluronan comes into contact with cells it causes a range of reactions, the nature of which depends on its size. High-mass hyaluronan stops cells from dividing and also shows anti-inflammatory properties, whereas low-mass hyaluronan has the opposite effect. Thus, the properties of high-mass hyaluronan may explain why cultured mole rat cells are much more ‘anti-social’ than those from other mammals, preferring to grow at a lower density than tissue from mice, humans or guinea pigs.
It was also found that mole rat cells are resistant to manipulations which would lead to tumour growth in other mammals. However, if HMM-HA production is reduced in mole rat cells then tumours are able to form. This indicates that the interaction between HMM-HA and the cell is vital for tumour resistance.
Scientists are now investigating how HMM-HA instructs cells to stop dividing. It is hoped that in the future an understanding of these mechanisms may open new avenues in the field of cancer prevention and life extension. So perhaps the enigmatic, awkward looking, naked mole rat is proof that beauty really is only skin deep!
Post by: Sarah Fox