Following on the heels of recent research that has linked microRNAs to tumor initiation and progression, researchers have now identified two new molecules that could serve as biomarkers to help predict brain metastasis in breast cancer patients.
By performing microRNA profile analysis on RNA taken from cancer stem-like cells isolated from a human breast cancer cell line and two highly metastatic variants of this cell line, scientists discovered that miR-7 is a metastasis suppressor in cancer stem-like cells.
Researchers then examined the molecular pathway downstream of miR-7 to find its targets and discovered that miR-7 suppressed expression of KLF4--which is inversely associated with brain metastasis-free survival but not associated with bone metastasis. This was tested in an animal model, where miR-7 expression significantly suppressed the ability of cancer stem-like cells to metastasize to the brain but not the bone.
After testing tumor samples from patients with breast cancer whose disease metastasized to the brain, researchers found that the two molecules play a critical role in cancer stem-like cell brain metastasis.
Metastatic disease is difficult to treat in the brain because few drugs can penetrate the blood-brain barrier, which blocks chemotherapy from reaching the brain. Most breast cancer deaths are a result of metastasis.
The findings were published in Cancer Research, a publication of the American Association for Cancer Research.
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