One of the first symptoms of breast cancer is an unusual stiffening of breast tissue.
This tissue stiffness is so crucial to tumor development that malignant (cancer-like) behavior can be caused in healthy breast cells by placing them in a stiffer environment.
Until now, though, researchers weren't sure how cells could detect tissue stiffness and why they react differently in healthy and malignant conditions.
But a team of scientists from the Institute for Bioengineering of Catalonia and Queen Mary University of London's Barts Cancer Institute have discovered the mechanism which allows cells to detect and adapt to tissue rigidity.
In a study published in Nature Materials, the researchers showed how the molecules that cells use to attach to their environment — called integrins — allow the cells to detect and adapt to tissue rigidity.
"In healthy breast cells, we have shown that the adhesive properties of integrins lead cells to reduce the force they apply to their environment if the tissue is stiffer than normal," said Pere Roca-Cusachs, said group leader at IBEC and assistant professor at the University of Barcelona.
"Because reducing force also reduces tissue stiffness, this mechanism can prevent tissue stiffening," Roca-Cusachs added.
But cancer cells in the breast express a different type of integrin with different adhesive properties.
This other integrin leads cells to apply higher forces as tissue stiffness increases, creating a feedback mechanism that can eventually lead to the hard lumps characteristic of breast tumors.
"Our study is the first time ever that a molecular mechanism of rigidity sensing by cells has been described, and it’s been demonstrated in healthy and unhealthy human breast cells," Pere said.
"Fascinatingly, abnormally rigid tissues are found not only in breast tumors but in several other types of cancer, which also express many different types of integrins. This means that mechanical changes induced by altered integrin expression could be a key aspect behind the onset of several diseases."
The researchers now plan to look at whether integrin regulation is a general mechanism of mechanical control of tissues, both healthy and diseased.
This could open up new avenues for treating cancers, they say.