Molecular Abnormalities in Breast Cancer

Recent findings have suggested additional molecular targets for drug development. Next generation sequencing studies from almost 900 breast cancers have identified hundreds of mutations whose corresponding protein activity falls into one of two categories: activation of the PI3K/AKT pathway and repression of the JUN/MAPK pathway^3,4,5,6. The resulting effects on the cell cycle are thought to disrupt the normal balance of cell proliferation and differentiation in mammary epithelium cells⁷.

A February 2014 study published in the Journal of Clinical Investigation reports a new classification scheme for breast cancers that is able to predict patient outcome⁸. It is based not on the characteristics of tumor cells but on the molecular phenotype of normal breast cells. Using over 15,000 healthy breast cells, a total of 11 cell types were identified. Tumor cells were subsequently classified into four major subtypes according to the presence or absence of vitamin D, androgen, and estrogen receptor expression. Expression of all three receptor types was associated with the best clinical outcome, while expression of none was associated with the worst.

New research suggests that a variety of molecular abnormalities are present in breast cancer cells. A number of potential therapeutic targets that have recently been identified will hopefully lead to novel treatments in the future.