UM-164, a Dual Inhibitor of c-Src and p38 MAPK, Suppresses Proliferation of Glioma by Reducing YAP Activity

SIMPLE SUMMARY: UM-164, as a high-potency c-Src inhibitor, is the original lead compound to be developed for targeting triple-negative breast cancer. Here we validated the fact that UM-164 induces the inhibition of glioma cell proliferation, migration and spheroid formation, as well as cell cycle arrest in the G1 phase. Moreover, UM-164 triggers YAP translocation to the cytoplasm, reduces the activity of YAP, and decreases the expression levels of CYR61 and AXL, which are generally known as YAP target genes. We further demonstrated that p38 appears to play a greater role than Src in the declined YAP activity mediated by UM-164. Additionally, UM-164 restrains glioma growth in vivo. Therefore, our data provide the first evidence that UM-164 exerts anti-tumor outcomes in glioma via the Hippo-YAP signaling pathway. ABSTRACT: UM-164 is a dual inhibitor of c-Src and p38 MAPK, and has been a lead compound for targeting triple-negative breast cancer. UM-164 shows stronger binding to the active sites of Src compared with the conventional Src inhibitor Dasatinib. While Dasatinib has displayed some inhibitory effects on glioma growth in clinical trials, whether UM-164 can suppress glioma growth has not been reported. Here we show that UM-164 suppressed the proliferation, migration and spheroid formation of glioma cells, and induced cell cycle arrest in the G1 phase. Moreover, UM-164 triggered YAP translocation to the cytoplasm and reduced the activity of YAP, as evidenced by a luciferase assay. Accordingly, UM-164 markedly decreased the expression levels of YAP target genes CYR61 and AXL. Importantly, ectopic expression of wild-type YAP or YAP-5SA (YAP constitutively active mutant) could rescue the anti-proliferative effect induced by UM-164. Intriguingly, p38 MAPK appears to play a greater role than Src in UM-164-mediated inhibition of YAP activity. Furthermore, the in vitro anti-glioma effect mediated by UM-164 was confirmed in a xenograft glioma model. Together, these findings reveal a mechanism by which UM-164 suppresses the malignant phenotypes of glioma cells and might provide a rationale for UM-164-based anti-glioma clinical trials.