It has been known that our DNA is arranged in a double helix structure since Watson and Crick first published their findings in 1953. sA Department of Chemistry research team at the University of Cambridge recently discovered a quadruple helix structure with clear links to cancer treatment, making this discovery a valuable one, indeed.
The research, funded by Cancer Research UK and published in Nature Chemistry this past January, proved the existence of four-stranded helices, also known as g-quadruplexes, in living human cells. Scientists were already aware that g-quadruplexes could exist in vitro, or within test tubes, but it is now known that they exist in vivo, within living cells, along with double helices. It took researchers 10 years to find proof, since they could only hypothesize its presence with computational modeling and lab experiments.
Researchers found that these four-stranded helices were formed in genomic areas of high guanine concentration — hence the name ‘g-quadruplex.’ Guanine is one of four nucleotides or building blocks that make up the genome’s coding.
The significance of this discovery is due to the g-quadruplexes’ direct link with cell division and production. The Cambridge research team, led by Giulia Biffi, created antibody proteins capable of detecting and tagging areas in the human genome where there was a high concentration of quadruple helix DNA structures. Its presence was then visualized with fluorescent markers that highlighted the antibodies, and therefore showed researchers where and when these special helices made an appearance during DNA replication.
According to Professor Balasubramanian, of the University of Cambridge and the Cambridge Research Institute, the DNA quadruple helices are more likely to be found in areas of rapid cell division, such as cancerous cells.
As the cell divided and DNA was replicated, the g-quadruplexes were at their highest concentration. The fluorescent markers were most intense when the mitosis was in its synthesis phase, which is when DNA is being replicated before cell division.
It was also proved that inhibiting DNA replication inhibited the intensity of the fluorescence from antibodies tagging the g-quadruplexes. This is extremely relevant for cancer research, since restriction of g-quadruplexes with synthetic molecules could potentially restrict cell division and stop the growth of tumors. With these synthetic molecules, replication of specific gene sequences can be halted, and these molecules can become treatments for cancer patients in the future.
