Figure 12. Schematic illustration of a regulatory mechanism of the MALAT1/miR-216b-5p/PNPO axis in breast ductal cancer. MALAT1 and PNPO are up-regulated, while miR-216b-5p is down-regulated, in breast cancer cells. The overexpression of MALAT1 mediates PNPO expression by competingly binding to miR-216b-5p, leading to the release of PNPO from the miR-216-5p interaction that avoids the PNPO degradation or translational inhibition. Suppression of PNPO can inhibit breast cancer cell proliferation, migration, invasion and colony formation, and promote breast cancer cell apoptosis.