Whales Have Low Risk of Cancer Due to Better DNA [Study]

Many were first perplexed as to why there are so few cancer instances in whales, given that cancer is inversely correlated with body size. The enigmatic conundrum has now been resolved, according to a recent study.

Why Do Giant Whales Have Lower Cancer Risks Than Humans?

Cancer is a condition characterized by uncontrollable cell division. Genetic abnormalities cause cells to divide, resulting in tumor-like aggregates repeatedly. Therefore, it makes sense to assume that larger animals would have more cells and that these cells would have a higher propensity to amass genetic mistakes that result in cancer, especially throughout a lengthy existence, ScienceAlert reported.

But when comparing mice and men in the late 1970s, famed British statistician Richard Peto found that this wasn't the case. Later research demonstrated that cancer does not become more prevalent regardless of the creature's size as the species' cell count increases. Like whales, elephants don't tend to develop many malignancies. This mismatch is called Peto's Paradox.

The second-largest yet longest-living species on Earth, the bowhead whale, Balaena mysticetus, has provided a solution to the contradiction, according to a team of researchers from the University of Rochester in New York.

The biologist Denis Firsanov and colleagues write in their preprint paper that by studying a mammal that can maintain its health and avoid dying from cancer for more than two centuries, we are given a special look behind the scenes of a grand evolutionary experiment that tested more mechanisms affecting cancer and aging than humans could ever hope to approach.

According to a set of laboratory tests, Bowhead whale cells outperform human, mouse, and cow cells at repairing DNA damage. Firsanov and colleagues noticed that whales prevent DNA damage "with unusually high efficiency and accuracy compared to other mammals."

Simply put, bowhead whales have a finely calibrated, rapid-repair system for mending DNA damage, which allows them to endure more strikes to their genomes. Whale cells were shown to be more capable of correctly repairing DNA breaks (caused by CRISPR) in a region of DNA shared by humans, mice, cows, and other species.

Additionally, bowhead whale cells produced a DNA repair protein called CIRBP at substantially higher rates than the other species under study. Further, this genetic modification enhanced the capacity of lab-grown human cells to repair DNA without errors.

The researchers concluded that the bowhead whale's long life and absence of cancer might depend on this technique, which does not destroy cells but restores them.

What Is Peto's Paradox?

Peto's Paradox is named after epidemiologist Richard Pete. He discovered the connection between time and cancer while researching the development of tumors in mice.

Peto noted that the length of exposure to the carcinogen benzpyrene was correlated with the likelihood of cancer progression. Later, when he pondered why humans do not have significantly different probabilities of acquiring cancer despite having 1000 times more cells than mice and living 30 times longer than them, he added body mass to the equation.

Cancer was not a significant cause of death in large and long-lived wild animals despite the elevated potential dangers. It prompted them to raise the question of how it was possible.

Based on the study that is yet to be peer-reviewed, it seems that those giant mammals have better DNA. Yale University cancer biologist Jason Sheltzer was not involved in the research and was fascinated with the result.

He says the study offers a new model to explain why big animals are not prone to cancer. He tweeted, "Maybe they're just better at DNA repair than us." He added that he wanted the study validated in an animal model. He suggested driving high expression of whale CIRBP protein to a mouse to see if they will resist cancer.

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