Breast cancers can be divided into different subtypes based on several criteria, including the marker proteins they express. Different tumor subtypes are associated with different clinical outcomes; for example, breast cancers lacking expression of the proteins to which hormones bind (so called triple-negative tumors [TNTs]) are associated with poor clinical outcomes.

A team of researchers, led by Eldad Zacksenhaus, at Toronto General Research Institute–University Health Network, Toronto, has generated new insight in mice into the genetic mutations that lead to the formation of different breast cancer subtypes. Their findings were reported in the Journal of Clinical Investigation.

Specifically, the team found that loss of the Rb gene in mouse breast tissue progenitor cells led to luminal-B and TNT breast tumor subtypes but that the TNT tumors also had mutations in p53. They therefore conclude that Rb loss can cause breast cancer in mice and that the presence or absence of other mutations, such as mutations in p53, determine the subtype.

SOURCE:
Journal of Clinical Investigation, August 2, 2010