It is known as the most common cancer-causing protein, and is directly responsible for 30 per cent of all cases.
Indirectly, it is involved in virtually all forms of the disease.
For more than 30 years, scientists have failed to successfully target the protein, known as Ras.
But now, researchers at the University of Toronto have discovered a way to ‘switch off’ Ras, using an experimental drug.
Their findings could prove to be a turning point in the fight against cancer.
Professor Michael Ohh, from the university’s Faculty of Medicine, said: ‘For several decades, scientists have tried to turn off a protein called Ras.
‘But despite their efforts, we ultimately haven’t seen much progress.
‘In fact, it’s been coined the “undruggable” protein.’
Normally, Ras promotes cell growth. But the protein can also cause uncontrolled cell growth when mutated or deregulated.
As a result, it is a key player in many forms of cancer and is mutated in more than 90 per cent of pancreatic tumours – one of the deadliest forms of the disease.
Professor Ohh and his team discovered another protein, called SHP2 was effective in turning off Ras.
He said: ‘Our lab is known for another area of cancer biology.
‘But on the request from a colleague, we entered the Ras field about five years ago to study mutations in a rare form of childhood leukaemia.
‘We were surprised to find that nobody had identified SHP2 as a switch that regulates Ras, that it could be targeted.’
Working with researchers from Indiana University and Toronto’s University Health Network, the team tested a SHP2 inhibitor on mice with glioblastoma – the most common and aggressive type of brain cancer.
The scientists were shocked to find the inhibitor drug reduced the tumours by more than 80 per cent.
‘The inhibitors’ results were incredible — we were shocked,’ said Professor Ohh. ‘Nothing has had the same effect.’
The researchers’ findings were recently published in Nature Communications.
Next, the team will work with a cancer surgeon at the University of North Carolina to treat mice that have human pancreatic tumours.
If the SHP2 inhibitor is effective, the researchers will use this evidence to support future human clinical trials.
Yoshihito Kano, co-author of the paper, who worked with primary author Severa Bunda, said: ‘In addition to being a researcher, I’m also a gastroenterologist and I see a lot of patients with pancreatic cancer.
‘These patients usually die within one year, even with chemotherapy, so this drug could potentially change my patients’ lives.’
While their research is in the early stages, Professor Ohh and his team hope their discovery will open up new perspectives in the field and potentially change cancer treatment,
He added: ‘By better understanding how this cancer-causing protein works, we hope to target it much more precisely than before.
‘At the end of the day, we want other researchers to build on our fundamental discovery, providing more options for patients.’