Breast cancer metastasis causes nearly 90% of the lethality among breast cancer patients. Non-metastatic breast cancer cells rely on interactions with other cells and the extracellular matrix to survive. Metastatic breast cancer cells must survive in the absence of these interactions.
Harvey et al hypothesized that Brk, a tyrosine kinase expressed predominantly in breast tumors compared with normal breast tissue, plays a role in breast cancer progression by promoting anchorage independence. Indeed, high-grade tumors from human breast cancer patients expressed elevated levels of Brk when compared with lower grade tumors. Inhibiting Brk expression resulted in cell death in the absence of cell-cell and cell-matrix interactions, and tumor cells with increased levels of Brk expression survived without these interactions. These data therefore support a role for Brk in breast cancer progression and dissemination.
Dr. Harvey and colleagues suggest “that Brk plays a role in protecting breast cancer cells from detachment-induced cell death. Therefore, Brk expression in carcinomas may confer a survival advantage on metastasizing tumor cells. … [Future studies will examine] whether this function is manifest in other Brk-positive tumor cells from tissues other than the breast, such as the colon and prostate.”
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