Blocking miR-21 overexpression was found to retrieve trastuzumab sensitivity in trastuzumab-resistant breast cancer cells, in a study of cell lines derived from HER2-postive breast carcinomas. This theory was derived from identification of overexpression of miR-21 in HER-positive, trastuzumab-resistant cells. The researchers also found that miR-21 upregulation in trastuzumab-resistant cells led to PTEN reduction.
The complete study was published in the May 27 issue of the Journal of Biological Chemistry (http://www.jbc.org/content/286/21/19127.long).