Natures wonders: low cancer rates (Introduction)

by David Turell , Friday, September 01, 2023, 18:27 (239 days ago) @ David Turell

In whales and elephants with different mechanisms:

https://mail.google.com/mail/u/0/#inbox/FMfcgzGtwqQdpjfGvpFVPlsHHvXCGNWT

"The existence of whales is a paradox—Peto’s paradox, to be specific. Here's the conundrum: How is it that large, long-lived creatures like whales don’t have a higher risk of developing cancer than we do? Theoretically at least, the risk of developing cancer should increase with both the number of cells an organism has and how long that organism lives. That’s because mutations have a chance of occurring every time cells divide and cells accumulate DNA damage as they age—so the more of them there are and the older they are, the higher the odds should be that some are cancerous. (my bold)

"But big baleen whales have unimaginable numbers of cells and can live into their 100s or even 200s, and yet, they aren’t riddled with tumors. Researchers have long sought to understand how these animals pull that off, in hopes of pointing oncologists towards new ways of preventing or treating human cancers.

"One popular idea is that these species have really, really, really slow mutation rates. This could solve the paradox: If changes to whales' cells happen at a glacial pace, then you’d expect fewer potentially cancer-causing mutations with each division and over a cell’s lifespan. But according to a study published in this week’s issue of Science, that’s simply not the case.

***

"Elephants appear to have solved the cancer problem by having tons of tumor-suppressing genes, but whales don’t. Instead, in a preprint recently posted to bioRxiv, a team of researchers from the University of Rochester provide evidence that one of the four species studied in the Science paper, the bowhead whale (Balaena mysticetus), is remarkably good at repairing total breaks in its DNA . So even though the overall mutation rate in the species isn’t lower, the animals’ cells are able to fix one kind of catastrophic damage that can lead to cancerous mutations.

"The Rochester team found that two proteins were particularly associated with this efficient genomic healing: CIRBP and RPA2. And when they modified mouse and human cells to produce more CIRBP, the cells ended up twice as good at repairing DNA breaks. “If we can regulate, somehow, our own CIRBP protein, that could absolutely be a strategy to reduce DNA damage in humans,” University of Bologna’s Antonello Lorenzini, who was not involved in the preprint, tells New Scientist.

"Even if this particular discovery doesn’t pan out in terms of treating human cancers, further research on whales and other species with unexpectedly healthy, long lives could. “We probably have the solution to cancer medicine out there in nature already,” evolutionary oncologist Orsolya Vincze tells Science News. “We just have to find it.'”

Comment: Note the bold. Cancers are the result of mistakes as cell split in mitosis, a very complicated process with many events occurring all at once, under tight controls. Our bodies cells do this trillions of times a day, which means cancer is actually a very rare outcome. This should be noted in the theodicy thread for dhw's edification.