A marker that shows how fast a tumour is growing opens a new line of attack on hard-to-treat cancers such as triple negative breast cancer.
Doctors use the protein, called Ki-67 to work out how aggressive a cancer is. But exactly how it works has been unclear.
Now, an international team has unpicked how Ki-67 and related protein RepoMan are built and function, pinpointing them as possible novel key targets for cancer therapy.
Removing RepoMan slows or stops cancer cell division, which in certain tumours goes into overdrive.
“There’s a new hope for treating these specific cancers,” said Brunel University London’s Dr Paola Vagnarelli.
“If we remove one of the proteins, the cells stop dividing so the cancer will not grow. And since we now know how they function, we can try to design specific drugs that only hit these particular proteins and do not harm normal cells, for example normal breast cells.”
It’s a major step in unlocking new lines of treatment for fast-growing cancers such as triple negative breast cancer which has a poorer survival rate and is less well understood than other breast cancers.
“For triple negative breast cancer, there are no efficient therapies,” said Dr Vagnarelli. “So knowing the molecular function of these proteins at different stages of the cell cycle, is a major hope for treating the highly aggressive triple negative breast cancer and many other cancers such as oral cancers.”
The study, in the journal eLife, explains how the team, including co-authors at Brown University in the US and the University of Leuven in Belgium, looked at individual atoms in the proteins and their behaviour in living cells. They pinpointed a unique pocket inside the two proteins, where they bind with another protein called PP1. This is exactly where new drug treatments will aim.
“This is a powerful approach” the study said. “It is now clear these novel unique protein interaction sites provide immediate opportunities for the design of novel highly specific therapeutics.”
● Brunel University London’s work was funded by the Biotechnology and Biological Sciences Research Council.