Scientists have identified an enzyme that is crucial for turning abnormal but non-malignant breast tissue into tumours, according to a study published today in Cell online.

Blocking the enzyme lysyl oxidase (LOX) reduced the chance a tumour would form, and also meant tumours that did develop were smaller and less aggressive.

"Our study shows that stiffening of the breast tissue controlled by enzymes such as LOX are a key factor in cancer development, suggesting these enzymes are a promising candidate drug target," study co-author Dr Janine Erler from The Institute of Cancer Research in the UK says. "The enzyme triggers a clear physical change in breast tissue and, if we could stop this happening, we expect it would slow the growth of any cancers that did develop and make them easier to eradicate."

The supportive tissue surrounding cancer cells is shaped differently to healthy tissue as well as stiffer and more fibrous. These properties help doctors detect breast cancers, but until now scientists have not known what was causing these modifications.

In the latest study, the team found LOX caused the structure of collagen, the major component of the supportive tissue, to change in a process known as cross-linking. In experimental models, higher levels of LOX increased the levels of collagen in mammary glands, made the tissue stiffer and correlated with a higher frequency of tumours invading the breast tissue…