Research may explain link between dense breast tissue and aggressive cancer
New US research may help to explain why women with dense breast tissue tend to develop a more aggressive form of breast cancer than those with less dense breasts.
Previous studies have shown that women with high breast density tend to have an increased risk of breast cancer, and of more invasive forms of the disease.
The latest study from Vanderbilt-Ingram Cancer Centre, published in the journal Current Biology, looked at cancer cells grown in the lab on different types of extracellular matrix - the material that surrounds cells in the body.
The researchers showed that cancer cells surrounded by a dense, rigid extracellular matrix appear to have more invadopodia - finger-like protrusions that are used to drill holes in the matrix so that they can invade the surrounding tissue.
Lead study author Dr Alissa Weaver, assistant professor of cancer biology, commented: "Our study shows that if you have a dense, rigid matrix, the cells will be more aggressive and invasive; it's a direct effect.
"If you have enough invadopodia, over time they'll make large holes that cells can move through to invade and metastasise."
Dr Weaver revealed that the team had expected a dense matrix to make it harder for the cells to get through - "But instead we found this interesting effect where cells actually sense the rigidity and degrade more.
"The idea that tissue rigidity leads to a more aggressive phenotype had been out there for a while, but it hadn't actually been tied to matrix degradation, which is thought to be important for metastasis and spread of cells through the body."
The researchers also identified two signalling proteins, FAK and p130Cas, which are active in invadopodia and appear to play an important role in triggering the higher amounts of matrix breakdown seen in dense breast tissue.
These proteins could prove to be good targets for treatments for aggressive forms of breast cancer in the future.