Suppression of cell invasion and tumor metastasis by miRZip-21 and increased metastasis using miRZip-145

To investigate the roles of miR-21 (oncogenic microRNA) and miR-145 (tumor suppressor microRNA) in breast cancer, cell invasion assays of MDA-MB-231 breast cancer cells were performed after lentiviral transduction with control vector lentivirus (Control) or miRZip-21 or miRZip-145 lentivirus. Matrigel chamber assays were then used to screen for invasive phenotypes.

After 20 h, invasion cells attached to the lower surface were fixed, followed by staining with 0.05% crystal violet. The number of invaded cells on the membrane was then counted under a microscope. Representative fields of invasive cells on the membrane are shown at the bottom for the Control and miRZip-21 or miRZip-145 treated cells.

The miRZip-21 lentivirus expressing anti-mir-21 small RNAs inhibited metastasis by 80% and the miRZip-145 lentivirus expressing anti-miR-145 RNAs increased metastasis by 60%. Additionally, the miRZip-145 lentivirus inhibited endogenous miR-145 and elevated protein expression levels of the miR-145 target oncogene c-Myc.

• List of miRZip clones