Acylglycerol kinase, a multisubstrate lipid kinase, cata lyzes the production of lysophosphatidic acid and phosphatidic acid from monoacylglycerol and diacylglycerol. Overex pression of AGK leads to activation of EGFR and promotes the proliferation and migration of prostate cancer cells, suggesting that AGK may possibly act as being a potent oncogene. On the other hand, the clinical significance of AGK and its associated signaling path ways stay unclear. Herein, we report that AGK is markedly overexpressed in esophageal squamous cell carcinoma and correlates with poorer condition absolutely free survival and shorter overall sur vival in principal ESCC. Moreover, we observed that AGK directly binds towards the JH2 domain of JAK2 and blocks JH2 mediated inhibi tion of JAK2, leading to constitutive activation of JAK2/STAT3 signaling and propagation within the CSC population in ESCC in vitro and in vivo.
Additional importantly, AGK expression was shown to cor relate considerably with XAV-939 clinical trial STAT3 regulated signatures in ESCC, lung cancer, and breast cancer patient gene expression profiles. These findings uncover a mutation independent mechanism of JH2 inhibition that sustains activation of JAK2 in solid tumors. Outcomes Identification of AGK as being a JH2 domain interacting protein that activates the JAK2/STAT3 pathway. To take a look at the mechanism by which reliable tumor cells override the autoinhibitory result of JH2 to sustain activation of JAK2/STAT3 signaling, affinity purification and mass spectrometry were made use of to identify JH2 interacting proteins in ECa109 ESCC cells. As shown in Figure 1, A and B, and Supplemental Figure 1A, AGK and 7 other proteins had been identified as potent JH2 interacting proteins. Importantly, reciprocal coimmunoprecipitation and Western blot assays even more demonstrated that AGK could type a complex with JAK2 and STAT3, suggesting that AGK might be involved within the regulation of JAK2/STAT3 signaling.
Indeed, we identified that amid these JH2 interacting partners, overexpres sion of AGK significantly elevated, whereas silencing of AGK decreased, STAT3 selleck inhibitor luciferase reporter activity plus the expres sion levels of phosphorylated JAK2 and phosphorylated STAT3. Additionally, as a result of analysis of AGK expression and STAT3 regulated gene signatures by means of gene set enrichment analysis in published ESCC patient expression profiles, we noticed that AGK

ranges in between regular and tumor tissues and within tumors had been positively correlated using the STAT3 activated gene signatures and inversely correlated together with the STAT3 suppressed gene signatures. Taken together, these effects propose that AGK contributes on the activation of JAK2/STAT3 signaling in ESCC.