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Cancer therapies Experts could learn a lot about elephants
Everyone has heard that elephants do not forget anything. But only very few people know that elephants almost never get cancer. Only 4.8 percent of all known fatalities in these pachyderms are due to cancer. In comparison, this value is much higher in humans. Between ten percent and 25 percent of human deaths are caused by cancer.
The low cancer rate in elephants is very amazing. Actually, the animals would have to get cancer more often than we humans. The reason is that elephants are much taller than humans. That means they have about a hundred times more cells than the human body. And the animals are very old, not infrequently 70 years or more. Over the course of this long life there are many chances for a large number of cells to mutate maliciously.
Certain genes protect elephants from cancer. (Image: donvanstaden / fotolia.com) Study reveals: elephants with special protection against cancer
For years scientists have been trying to find out why elephants and other large mammals do not get more cancer than smaller mammals. There is even a name for this problem - Peto Paradox. Now scientists have managed to solve the mystery of pachyderms. The JAMA Journal of the American Medical Association published a study on this topic this week. Scientists revealed that elephants have twenty copies of a gene called TP53. This gene is highly valued by cancer researchers for a special trait: it has the ability to produce a protein that suppresses tumors. Humans have only one copy of this gene. The key gene protects cells against cancer in two ways. When DNA damage occurs, TP53 causes cell division to stop. This would allow the body to repair the damaged DNA, Dr. Joshua Schiffman, co-author of the study, from the Huntsman Cancer Institute in Salt Lake City.
People with defective Tp53 gene definitely get cancer
Every human inherits two of these TP53 genes. A gene from the mother. The second gene is inherited from the father. Both genes must be intact and work. Should any of these genes be defective, it will certainly cause cancer sooner or later.
Cancer in elephants is less than five percent
Schiffman now considered whether elephants may rarely get cancer because they are protected by many more TP53 genes. So he put together a team and began to do a study on this topic. First, it was important to find out how rare cancer is in elephants. This information came from the research team in the Elephant Encyclopedia. This is a collection of information about captive pachyderms around the world. The database contains details of the deaths of 644 elephants. The researchers now calculated that only about 3.11 percent of elephants had cancer when they died. In addition, every case with an unexplained cause of death was also attributed to the cancer. The result increased only minimally and amounted to 4.81 per cent.
Elephant cells do not regenerate faster than humans
The next step was to take a closer look at the genomes of the African elephant. The researchers found that these elephants had twenty copies of the TP53 gene. Now it was determined whether these genes were the reason that pachyderms so rarely get cancer. The physicians collected white blood cells from humans and elephants. These were exposed to extreme radiation, thereby breaking their DNA. The researchers expected that the increased number of TP53 genes would regenerate the elephant cells faster. Surprisingly, this was not the case.
Elephant cells do not regenerate, they destroy themselves
Instead, Schiffmann and his colleagues observed that elephant cells died at a much higher rate than human cells. Part of TP53's strategy is that damaged cells destroy themselves. Thus, it is impossible for them to develop potentially harmful mutations. The tactics of the elephants seems to be plausible. Cancer is so dangerous that it can not be risked to repair damaged DNA. The best way is to completely destroy an infected cell to prevent cancer. So there would be no way that the cancer spreads or mutates, said the physician Schiffman. In another experiment, the researchers found that irradiated elephant cells destroy each other at twice the speed of human cells with intact TP53 genes. If one compares defective TP53 genes in humans, it can be seen that the self-destruction rate in elephant genes is more than five times as fast.
New TP53-like drug could protect against cancer
These facts lead to the conclusion that these extra copies of TP53 have evolved in the course of evolution to protect elephants from cancer. To really prove this thesis, you would first have to create an elephant without TP53 genes. This is the only way to see if this elephant is more susceptible to cancer. Schiffman. The physician also said that the study's findings should be used to help cancer patients. One possibility would be to develop a drug that mimics the actions of TP53. (As)