MicroRNA may help breast cancer prognoses

CAMBRIDGE, Mass., June 17 (UPI) -- A U.S. animal study suggests a new method to more accurately predict the likelihood of metastasis of breast cancer occurring in humans.

Whitehead Institute for Biomedical Research scientists determined a low cellular level of a tiny fragment of RNA appears to increase the spread of breast cancer in mouse models of the disease. They said measuring levels of the so-called microRNA, which is also associated with metastatic breast cancer in humans, may help determine patient prognoses.

Scott Valastyan, a graduate student in Professor Robert Weinberg's laboratory, screened patient breast cancer samples for microRNAs with potential roles in metastasis. The screened samples were classified as either metastatic cancer or non-metastatic cancer. After analysis, the researchers said the microRNA miR-31 stood out because of its inverse correlation with metastasis.

In samples where a patient's original tumor had not metastasized, the cancer cells retained high levels of the microRNA. But where the tumor had metastasized, the cancer cells possessed lower levels of miR-31.

"This microRNA seems to be quite unique, in that it seems to provide some prognostic utility across these existing subclassifications (of cancers)," Valastyan said.

The research is reported in the journal Cell.