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• Posted July 19, 2024

Ancient Viruses Might Be Spurring Modern-Day Cancers

Cancer growth can be fueled by flecks of ancient viral DNA lodged into the genetics of modern humans, a new study says.

Overall, about 8% of the human genome is made of bits of DNA left behind by viruses that infected our primate ancestors, researchers say.

Called “endogenous retroviruses,” these DNA fragments have long been considered harmless junk littering the modern human genetic profile, researchers said.

But new research shows that when reawakened, these ancient viral strands can help cancer survive and thrive, researchers reported July 17 in the journal Science Advances.

What’s more, shutting up these viral voices from the past can make cancer treatments more effective, researchers found.

“Our study shows that diseases today can be significantly influenced by these ancient viral infections that until recently very few researchers were paying attention to,” said senior researcher Edward Chuong.

Hes an assistant professor of molecular, cellular and developmental biology at the University of Colorado, Boulder’s BioFrontiers Institute.

Eons ago, viruses baked their DNA into humans by infiltrating sperm, eggs and embryos, shaping human evolution along the way.

While these genetic vestiges can no longer produce functional viruses, they can activate nearby human genes in ways that could affect health, researchers said.

In this study, researchers found that a specific virus called LTR10 -- which infected primates 30 million years ago -- showed surprisingly high levels of activity in several types of cancer.

LTR10 was active in about a third of tumors taken from dozens of colorectal cancer patients, researchers found. It also was very active in lung cancers.

And when researchers used gene-editing tools to cut out LRT10, they discovered that genes known to promote cancer development and growth also went dark.

“We saw that when you silence this retrovirus in cancer cells, it turns off nearby gene expression,” said lead researcher Atma Ivancevic, a research associate in Chuong’s lab.

Experiments in mice yielded similar results. Removing LTR10 from tumor cells caused cancer treatments to work better at shrinking tumors.

“We know that cancer cells express a lot of genes that are not supposed to be on, but no one really knows what is turning them on,” Chuong said in a university news release. “It turns out many of the switches turning them on are derived from these ancient viruses."

More information

The American Physiological Society has more on human endogenous retroviruses.

SOURCE: University of Colorado, Boulder, news release, July 17, 2024