Non-coding DNA sequence could play a role in aging and cancer

August 2, 2021

A repetitive non-coding DNA sequence that varies greatly in length from human to human has been shown to play a role in aging and cancer.

An international group of scientists have examined a region of DNA called VNTR2-1. They found that removing this region reduced tumor growth and contributed to cell aging. Researchers have found that this region controls the activity of an enzyme called telomerase which is responsible for the production of telomeres, regions of DNA found at the ends of chromosomes that protect them from damage or fusion with the ends. other strands.

“Almost 50 percent of our genome is made up of repetitive DNA that does not code for proteins. Our study describes that one of these units actually has a function in that it enhances the activity of the telomerase gene. ‘ said Professor Jiyue Zhu, professor of pharmaceutical sciences at Washington State University, Pullman.

Telomeres shorten every time a cell divides, and when it gets too small, cells age and die. But in some types of cells, including some cancer cells, telomerase activity ensures that the length does not shorten every time the cell divides and the cell does not age and die as it would. normally. This is one of the reasons why cancer cells grow uncontrollably and form tumors.

“Our results tell us that this VNTR2-1 sequence contributes to the genetic diversity of how we age and how we get cancer.” Professor Zhu added.

In this study, published in Proceedings of the National Academy of Sciences, several approaches were taken. Removal of the VNTR2-1 region in cancer cells from human cell lines and mice resulted in shorter telomere length, arrest of tumor growth and cell aging.

The U.S. researchers also conducted a VNTR2-1 sequence length study in participants of the Georgian Centenarian Study, which followed a group of whites and African Americans aged 100 or older. Sequence lengths ranged from shorter to much longer, some as short as 53 repeats in the region, to some as long as 160 repeats. Very short sequences were only found in African American participants.

A shorter sequence of VNTR2-1 does not necessarily lead to a shorter lifespan. This is because telomerase activity is lower, which shortens the length of telomeres in cells and reduces the risk of developing into cancer cells.

We know that oncogenes – or cancer genes – and tumor suppressor genes don’t explain all the reasons we get cancer. Our research shows that the picture is much more complicated than a mutation in an oncogene and argues for expanding our research to take a closer look [noncoding DNA]. ‘ said Professor Zhu.