Shark DNA could help unlock key to cancer and other diseases

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Photo courtesy of Byron Dilkes and Danah Divers

Photo courtesy of Byron Dilkes and Danah Divers

In a major scientific step toward understanding the biology of great white sharks, it entire genome has been decoded in detail, which could shed light on cancers and age-related diseases in humans.

A team led by scientists from Save Our Seas Foundation Shark Research Center, Guy Harvey Research Institute, Cornell University College of Veterinary Medicine and Monterey Bay Aquarium decoded the white shark genome and compared it to those from a variety of other vertebrates, including humans.

Sequence changes were found tied to DNA repair, DNA damage response and DNA damage tolerance, the opposite of which — genome instability — is known to predispose humans to numerous cancers and age-related diseases, according to researchers.

“Not only were there a surprisingly high number of genome stability genes that contained these adaptive changes, but there was also an enrichment of several of these genes, highlighting the importance of this genetic fine-tuning in the white shark,” said Mahmood Shivji, director of Nova Southeastern University’s Save Our Seas Foundation Shark Research Center and GHRI, in a statement.

Shivji co-led the study with Michael Stanhope, of Cornell University College of Veterinary Medicine. “We found positive selection and gene content enrichments involving several genes tied to some of the most fundamental pathways in wound healing, including in a key blood clotting gene,” Stanhope said. “These adaptations involving wound healing genes may underlie the vaunted ability of sharks to heal efficiently from even large wounds.”

The researchers say they have just explored the “tip of the iceberg” with respect to the white shark genome.

“Decoding the white shark genome is providing science with a new set of keys to unlock lingering mysteries about these feared and misunderstood predators — why sharks have thrived for some 500 million years longer than almost any vertebrate on earth,” said Salvador Jorgensen, a senior research scientist at the Monterey Bay Aquarium, who co-authored the study.

The researchers found occurrences of specific DNA sequence changes indicating molecular adaptation — also known as positive selection — in numerous genes with important roles in maintaining genome stability. Maintaining that stability is the genetic defense mechanism that counteracts the accumulation of damage to a species’ DNA, preserving the integrity of the genome.

These adaptive sequence changes were found in genes intimately tied to DNA repair, DNA damage response and DNA damage tolerance, among other genes. The opposite phenomenon, genome instability, which results from accumulated DNA damage, is well known to predispose humans to numerous cancers and age-related diseases.

“Genome instability is a very important issue in many serious human diseases. Now we find that nature has developed clever strategies to maintain the stability of genomes in these large-bodied, long-lived sharks,” Shivji said. “There’s still tons to be learned from these evolutionary marvels, including information that will potentially be useful to fight cancer and age-related diseases, and improve wound-healing treatments in humans, as we uncover how these animals do it.” 

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