when virus When they come to visit us, they sometimes leave a piece of themselves behind.
Some of these foreign DNAs, tucked away in our genomes, can be passed down through generations. For a long time they were thought to be inactive, but then it was discovered that these stowaway sequences can become active again and cause all sorts of chaos.
Researchers led by University of Colorado bioinformatics researcher Atma Ivancevic have discovered that cancer may exploit some of these zombies. virus They use the parts for their own gain.
“Our study shows that these ancient viral infections, which until recently went largely unnoticed by researchers, may have a major impact on diseases today.” To tell Edward Truong, genome biologist and senior author.
Long ignored as “junk” DNA, we now know that fragments of virus debris Endogenous retroviruses (ERV) prompted our existence as mammals. Evolution of the placentawe not human Without them.
But like most things, ERVs come with a cost. I’m just beginning to understand.
“We know that cancer “Cells express a lot of genes that shouldn’t be active, and no one knows what makes them active.” explain “It turns out that many of the switches that turn them on come from these ancient viruses,” Truong said.
Ivancevic and her team analyzed public data sets on the epigenomes of 21 different cancers and were surprised to find that a particular family of ERVs called long terminal repeat 10 (LTR10) was active at very high levels, the original virus that infected our primate ancestors about 30 million years ago.
Functional studies performed in colon cancer tissue cell lines revealed that LTR10 controls the expression of genes with established roles in tumor generation.
Inactivating the LTR10 gene in human colon cancer cells and mice also inactivated genes that drive cancer growth, including XRCC4, a gene known to be involved in treatment resistance, making the treatment more effective at shrinking tumors in the mice.
LTR10 functions as an epigenetic switch that controls these genes, Ivancevic and his team conclude.
Cancers appear to use these discarded viral parts to alter gene expression patterns throughout tumors, with just one retrovirus family controlling as many as 70 cancer-related genes.
Although Ivancevic and his colleagues have determined which genes LTR10 regulates in tumor cells, they are unable to directly confirm that those genes are associated with the growth and spread of specific cancers, and they recommend further study of patient-derived genes. Organoids It’s to make those connections.
Researchers believe that as we age, our defenses weaken, making it more likely that fragments of the zombie virus can reanimate. Causes other health problems In his later years.
Slowly but surely, scientists are digging into the more obscure parts of our biology that lie behind these complex symptoms.
This study Scientific advances.
