The discovery of a ‘quadruple helix’ in human cells could be a key to fighting cancer, say the Cambridge researchers who made the findings.
They come almost exactly 60 years after James Watson and Francis Crick burst in to the pub next to their Cambridge lab excitedly proclaiming that they had found the secret of life in the double helix structure of DNA.
Quadruple helixes intertwine four rather than two strands of DNA, and had been created in the lab by curious researchers, but it was generally thought that they didn’t exist in nature.
The quadruple helix had only been seen when it was created by researchers in test tubes, but now scientists have identified them in cancer cells
But now these quadruple helixes – or G-quadruplexes – have been found in cancer cells, according to a study published in Nature Chemistry.
The quadruple helix might be unique to human cancer cells – and the discovery means that cancer drugs to target these unusual DNA structures could be developed.
‘We are seeing links between trapping the quadruplexes with molecules and the ability to stop cells dividing, which is hugely exciting,’ said Professor Shankar Balasubramanian from the University of Cambridge’s Department of Chemistry and Cambridge Research Institute.
Shankar Balasubramanian stands in front of a painting called ‘Living the Code’ by artist Annie Newman at his office in Cambridge University’s Department of Chemistry
Cambridge scientists Francis Crick and James Watson with a model of the double helix of DNA, which they discovered in 1953
The research, which has been funded by Cancer Research UK, shows clear links between concentrations of four-stranded quadruplexes and the process of DNA replication, which is pivotal to cell division and production.
WHAT IS DNA?
DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms.
Nearly every cell in a person’s body has the same DNA.
DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it nuclein.
In 1953, Cambridge scientists James Watson and Francis Crick suggested what is now accepted as the first correct double-helix model of DNA structure in the journal Nature.
Their double-helix, molecular model of DNA was then based on a single X-ray diffraction image taken by Rosalind Franklin and Raymond Gosling in May 1952.
Cancers are usually driven by genes called oncogenes that have mutated to increase DNA replication – causing cell proliferation to spiral out of control, and leading to tumour growth.
The increased DNA replication rate in oncogenes leads to an intensity in the quadruplex structures. This means that potentially damaging cellular activity can be targeted with synthetic molecules or other forms of treatments.
‘This research further highlights the potential for exploiting these unusual DNA structures to beat cancer – the next part of this pipeline is to figure out how to target them in tumour cells,’ said Dr Julie Sharp, senior science information manager at Cancer Research UK.
Balasubramanian told the BBC: ‘I’m hoping now that the pharmaceutical companies will bring this on to their radar and we can perhaps take a more serious look at whether quadruplexes are indeed therapeutically viable targets.’
He added: ‘The quadruple helix DNA structure may well be the key to new ways of selectively inhibiting the proliferation of inhibiting the proliferation of cancer cells.
‘The confirmation of its existence in human cells is a real landmark.’