A couple of years ago, I wrote a post in praise of the naked mole rat, an exceedingly odd little creature with seemingly super powers when it comes to health and longevity. Well, scientists have recently discovered why these things don’t get cancer, something that could lead to treatments in human beings. [Read more…]
Scientists have sequenced the genome of a strange little creature, the naked mole rat. Why? Because it never gets cancer, lives an unbelievably long life without mental decline, and has many other amazing powers that may hold clues for human health.
Mole rats are hairless, buck-toothed rodents four inches long that live in underground colonies in arid sections of Kenya, Ethiopia, Somalia and Eritrea. Their social structure is the mammalian equivalent of an ant colony. There’s a queen who takes two or three male consorts and is the only female to reproduce. She lords over the rest of the realm — which can be as large as 200 animals — so that the other females cease ovulating and the males give up.
Mole rats can survive in environments low in oxygen (as little as 8 percent as opposed to 21 percent in the atmosphere) and laden with ammonia and carbon dioxide. Unlike other mammals (but like reptiles), they have a hard time regulating their body temperature. They have to move toward the warmer upper reaches of the burrow or huddle with their brethren when they get cold.
But their most unusual features are extreme longevity and apparently complete resistance to developing cancer.
Naked mole rats can live more than 25 years; mice live about four. Buffenstein said she has never found a malignant tumor in a mole rat in her 30-year-old colony, which has 2,000 animals. In a recent experiment, a group of mole rats had patches of skin painted with a chemical carcinogen at a dose 1,000 times stronger than what causes skin cancer in mice. None developed tumors.
A study published in 2009 found that naked mole rats had a molecular anticancer mechanism not present in mice or people. But a first look at the species’ full complement of 22,561 genes shows that’s just the beginning.
There are changes in genes involved in maintaining telomeres, the “tails” of chromosomes that determine how long a cell lives. There are changes in genes involved in marking damaged proteins for destruction. There’s an increase in “chaperone” genes that keep proteins folded into their right shapes. There are genes that appear to let the animals maintain stem cells in their tissues longer than other rodents.
The study looked at 54 human brain genes that become less or more active as a person ages. In the mole rat, 30 of those genes remain stable throughout life, and two others change their activity in a direction opposite to what occurs in human brains.
Mole rats have 96 gene families unique to the species. Interestingly, they and humans also share 178 gene families that neither mice nor other rats have.
A study of hundreds of Egyptian mummies and other ancient evidence has found virtually no cases of cancer, which first seems to turn up at the advent of the modern world. Here are some of the conclusions from researchers:
Cancer is a man-made disease fuelled by the excesses of modern life, a study of ancient remains has found.
Tumours were rare until recent times when pollution and poor diet became issues, the review of mummies, fossils and classical literature found.
A greater understanding of its origins could lead to treatments for the disease, which claims more than 150,000 lives a year in the UK.
Scientists found no signs of cancer in their extensive study of mummies apart from one isolated case
Despite slivers of tissue from hundreds of Egyptian mummies being rehydrated, just one case of cancer has been confirmed. This is even though tumours should be better preserved by mummification than healthy tissues.
Fossil evidence is also sparse, with just a few dozen – mostly disputed – examples, Nature Reviews Cancer journal reports.
Even the study of thousands of Neanderthal bones has provided only one example of a possible cancer.
And references to cancer-like problems in ancient Egyptian texts are more likely to have been caused by leprosy or varicose veins.
Researcher Michael Zimmerman, a visiting professor at Manchester University, said: ‘The virtual absence of malignancies in mummies must be interpreted as indicating their rarity in antiquity. This indicates that cancer-causing factors are limited to societies affected by modern industrialisation.’
The ancient Greeks were probably the first to define cancer as a specific disease and to distinguish between benign and malignant tumours.
But researchers said it was unclear if this signalled a real rise in the disease, or just a greater medical knowledge.
The 17th century provides the first descriptions of surgery for breast and other cancers, while the first reports of distinctive tumours occurred in the past 200 years or so.
They include scrotal cancer in chimney sweeps in 1775 and nasal cancer in snuff users in 1761.
Co-researcher Professor Rosalie David said: ‘There is nothing in the natural environment that can cause cancer.
‘So it has to be down to pollution and changes to diet and lifestyle.
‘The important thing about our study is that it gives a historical perspective to this disease.