Why is elephant cancer rare? Answer might help treat humans

Obviously, we inherent one copy maternally and one copy paternally. “My question is whether any of these genes have a function”. And TP53, as Schiffman and other scientists describe it, is the so-called “Guardian of the Genome”. Additional studies will be needed to determine whether p53 directly protects elephants from cancer. It detects stress or damage in the cell, and stops the cell from dividing until the stress has passed or the DNA is repaired.

“If you’re looking at prevention of cancer, which I think has huge promise, then we need to focus on lifestyle”, Greaves said in an interview.

So where do elephants come in?

“Twenty years ago, we founded the Ringling Bros“.

That’s a paradox known among scientists, and now researchers think they may have an explanation. Research indicates that p53 can be hijacked by certain cancers to spread the disease further, once its natural security system is compromised by the rogue tumor cells. But the opposite is true.

His team – as well as a second group of scientists – pinned down the size of the elephants’ surplus – 20 copies.

“Of note, over half of all human cancers are missing functional p53, another clue to its importance in suppressing cancer”, Schiffman said. “The blood samples from our elephants at Utah’s Hogle Zoo are aiding Dr. Schiffman in his research, and we are proud to be a part of his ground-breaking work”.

“In isolated elephant cells, this activity is doubled compared to healthy human cells”, said the study, which was co-authored by experts from Arizona State University and the Ringling Bros Center for Elephant Conservation. Ringling Bros also provided funding. (Around 3% of elephants get cancer, according to the team’s analysis of hundreds of captive-elephant deaths).

At least one solution to Peto’s paradox may now have been found, according to a pair of papers independently published this week.

When the researchers looked closely at a sequenced elephant genome, they discovered that unlike humans who have two copies of the TP53 gene, elephants have evolved to have 40 copies of the cancer-protective gene. They found that while the elephant and human cells repaired DNA at a similar rate, elephant cells underwent significantly more cell death-which is one way a body fights cancer. These two animals, as well as elephants, do share a strategy of genetically killing off damaged cells. People who have a defective version – a condition called Li-Fraumeni syndrome – usually get cancer in childhood, and their lifetime risk is close to 100 per cent. The extra copies of the p53 gene enable elephants to kill off potentially cancerous cells before they form tumors. The animals’ cells carry out a controlled self-destruction called apoptosis in response to DNA damage at much higher rates than do human cells. Schiffman says this supports the argument that more p53 means more cancer protection.

This study should be seen as an interesting story about elephants rather than giving short-term hope for cancer patients, said Bert Vogelstein of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center. “Evolution has had 55 million years to figure out how to prevent cancer in elephants, and now it’s our turn to try to figure out how to apply this to people”. For instance, Schiffman says there might be drugs that already exist or we don’t know about yet that can do that.

The myth that sharks dont get cancer has encouraged people to kill them and sell their cartilage for nutritional supplements.

In a corresponding editorial, Mel Greaves and Luca Ermini of the Institute of Cancer Research, London write, “The conclusion that elephants owe their relatively cancer-free longevity to the acquisition, in an ancestor, of extra copies of TP53 seems plausible”. They then subjected the cells to treatments that damage DNA, a cancer trigger. All that growth involves cell division, a process that provides opportunities for potentially lethal genetic mistakes.