Salvia miltiorrhiza Bunge (Danshen) has been widely used to treat cancer and cardiovascular diseases in Chinese traditional medicine. Here, we found that Neoprzewaquinone A (NEO), an active component of S. miltiorrhiza, selectively inhibits PIM1. We showed that NEO potently inhibits PIM1 kinase at nanomolar concentrations and significantly suppresses the growth, migration, and Epithelial-Mesenchymal Transition (EMT) in the triple-negative breast cancer cell line, MDA-MB-231 in vitro. Molecular docking simulations revealed that NEO enters the PIM1 pocket, thereby triggering multiple interaction effects. Western blot analysis revealed that both NEO and SGI-1776 (a specific PIM1 inhibitor), inhibited ROCK2/STAT3 signaling in MDA-MB-231 cells, indicating that PIM1 kinase modulates cell migration and EMT via ROCK2 signaling. Recent studies indicated that ROCK2 plays a key role in smooth muscle contraction, and that ROCK2 inhibitors effectively control the symptoms of high intraocular pressure (IOP) in glaucoma patients. Here, we showed that NEO and SGI-1776 significantly reduce IOP in normal rabbits and relax pre-restrained thoracic aortic rings in rats. Taken together, our findings indicated that NEO inhibits TNBC cell migration and relaxes smooth muscles mainly by targeting PIM1 and inhibiting ROCK2/STAT3 signaling, and that PIM1 may be an effective target for IOP and other circulatory diseases.
Keywords: Neoprzewaquinone A; PIM1; ROCK2/STAT3 signaling pathway; TNBC; cell migration; glaucoma.