Grincamycin B Functions as a Potent Inhibitor for Glioblastoma Stem Cell via Targeting RHOA and PI3K/AKT.

Glioblastoma multiforme (GBM) is the most malignant form of glioma, and the overall survival time of patients with GBM is usually less than 14 months. Therefore, it is urgent to find new and effective medicine for GBM. Recently, marine natural products have been shown to exhibit strong inhibitory effects on cancer cells, providing a new avenue for exploring novel drugs for GBM treatment. In this study, we investigated the inhibitory effect of the Grincamycin (GCN) B-F, newly isolated from marine-derived Streptomyces Lusitanus SCSIO LR32, on GBM cells, and evaluated the mechanism of GCN B on GBM. The results, for the first time, showed that GCN B acted as a potent inhibitor to suppress growth and invasion of two human GBM cell lines U251 and 091214 in vitro. In addition, GCN B could effectively target GSCs in GBM evidenced by attenuated formation of tumor spheres and decrease of several markers of GSCs. Furthermore, we performed gene expression microarray followed by Signal-Net analysis. The result revealed that RHOA and PI3K/AKT axis played critical roles for a GCN B-mediated inhibitory effect on GSCs. Altogether, our findings highlighted GCN B as a promising inhibitor for GSCs via targeting RHOA and PI3K/AKT.