Mechanism that makes breast cancer invasive identified

Researchers have identified a mechanism that causes breast cancer to spread. Amplification of the gene for ErbB2 has been associated with aggressive forms of breast cancer that are resistant to treatment. ErbB2-positive breast cancers are treated with chemotherapy and Herceptin, an ErbB2-targeted drug, but treatment often fails. The researchers discovered that ErbB2 induces expression of proteins called cathepsins. Cathepsins have been linked to metastasis of pancreatic cancer, particularly with tumor cell invasion of surrounding tissues. Using a three-dimensional model to study ErbB2-induced cellular invasion, the study showed that inhibition of cathepsins prevented ErbB2-driven breast cancer invasion.