Association Of YAP With Gastric Cancer And Biological Activity Of YAP Inhibitor Against Gastric Cancer

Objective:To explore the feasibility of YAP as a therapeutic target for gastric cancer(GC)by systematic meta-analysis,as well as screen small molecule YAP inhibitor and evaluate its biological activity and related mechanisms of action in GC treatment.Methods:(1)We performed a systematic literature search in the Chinese National Knowledge Infrastructure(CNKI),PubMed,Embase and Web of Science databases(WOS)from inception up to January 2019.Two investigators independently screened literature and extracted data according to inclusion and exclusion criteria.The quality of each study was evaluated based on the Newcastle-Ottawa Scale(NOS).All statistical analyses were performed using the software Stata version 12.0.The pooled odds ratios(ORs)and corresponding 95%CIs were used to assess the strength of association.The heterogeneity among eligible studies was evaluated by the Q-test and I~2 values.The sensitivity analysis was performed by sequential omission of individual studies.Moreover,Begg’s test and Egger’s test were used to evaluate publication bias.(2)The dual-luciferase reporter gene detection system was used to screen YAP inhibitors.MTT assay,colony formation test and wound healing assay were conducted to assess the in vitro anti-GC effects of YAP inhibitor.The antiangiogenic activity of YAP inhibitor was evaluated by the endothelial cell migration,invasion,and tube formation assays.Furthermore,we also detected the inhibitory effects of YAP inhibitor on cancer stem cell self-renewal and epithelial mesenchymal transformation(EMT)by Aldeluor flow cytometry,tumorsphere formation assay and western blot analysis.In addition,transcriptome analysis was performed to preliminarily explore the mechanism of OSU-HDAC42 against YAP expression in GC.Results:(1)A total of 2229 patients from 16 studies were included in this meta-analysis.The results showed that positive YAP expression was closely correlated with GC but not adjacent non-tumor tissue(OR=8.08,95%CI=4.41-14.80).Additionally,YAP overexpression was found to be associated with more advanced TNM stage(OR=2.68,95%CI=1.61-4.48),deeper invasion depth(OR=2.05,95%CI=1.32-3.19),and lymph node metastasis(OR=1.95,95%CI=1.29-2.96).In addition,sensitivity analysis indicated the reliability and stability of the meta-analysis,and the Begg’s test and Egger’s test showed the absence of significant publication bias in this meta-analysis.(2)OSU-HDAC42 was screened as a potential YAP inhibitor with high activity by dual-luciferase reporter assay;this compound could significantly restrain YAP expression and the activity of its downstream targets CTGF and Survivin in GC cells.In in vitro pharmacodynamic studies,OSU-HDAC42 significantly suppressed the growth and migration of GC cells even at low concentrations.Meanwhile,OSU-HDAC42 displayed moderate antiangiogenic activity in the assessment conducted in endothelial cells;it could significantly inhibit the migration,invasion and tubulogenesis of human umbilical vein endothelial cells.Furthermore,OSU-HDAC42 treatment significantly reduced the number of ALDH1-positive cell aggregation(cancer stem cell-like cells),and potently inhibited the capacity of sphere-forming,as well as the expression of EMT and cancer stem cell related proteins in oral cancer cells,exhibiting potential efficacy against EMT phenotype of cancer cells and self-renewal of cancer stem cells.Combining the results of transcriptome sequencing and bioinformatics analysis,we speculated that OSU-HDAC42may inhibit YAP function by affecting the regulation of Wnt and TGF-βsignaling pathways.Conclusion:This study demonstrated that YAP may be a potential diagnostic marker and even a therapeutic target for GC.OSU-HDAC42 is a highly active YAP inhibitor,it deserves to be further studied as a YAP inhibitor,and is worthy to be further assessed as a potential drug candidate for GC treatment.