Mechanisms By Which Upregulation Of ASAP2 Affects Prognosis And Immune Infiltration In Pancreatic Cancer

Objective:Pancreatic cancer(PC)is a gastrointestinal tumour with an extremely low 5-year survival rate.ArfGAP with SH3 structural domain,Ankyrin repeat sequence and PH structural domain 2(ASAP2)has been associated with the development of a variety of tumours.However,the role of ASAP2 in PC and its mechanisms are not fully understood.The aim of this study was to investigate the clinical significance of ASAP2 expression in PC,its role and its associated mechanisms.Methods:The expression of ASAP2 in pancreatic cancer tissues was analysed by the ONCOMINE database,the Gene Expression Omnibus(GEO)database,GEPIA and The cancer genome atlas(TCGA)databases,and validated by qPCR in our collection of The results were validated by qPCR on clinical specimens collected from pancreatic cancer patients.The prognostic value of ASAP2 in pancreatic cancer was assessed based on the ASAP2 expression data and clinical data of pancreatic cancer patients in the TCGA database.Genes co-expressed with ASAP2 in pancreatic cancer were obtained using the cBioPortal database and the Ualcan database for GO and KEGG functional enrichment analysis.After overexpression and and knockdown of ASAP2,cell proliferation viability was detected using the Cell Counting Kit-8 assay(CCK-8)and flow cytometry based on the results of the analysis,and scratch assays and Transwell assays were used to detect cell migration and invasion,and Western blotting assays were used to detect changes in the PI3K-AKT signalling pathway and key proteins in the Epithelial-Mesenchymal Transition(EMT)following ASAP2 knockdown and overexpression.Meanwhile,miRNAs that could bind to ASAP2 mRNA 3UTR and inhibit ASAP2 expression were reverse predicted through multiple miRNA online target prediction databases and functionally validated using dual luciferase reporter assays and the above cellular assays.Finally,correlations between ASAP2 and pancreatic cancer immune cell infiltration levels,chemokines and their receptors were analysed by ssGSEA,XCELL algorithm and TISIDB database.Results:Analysis of the gene expression dataset of ASAP2 in ONCOMINE,GEPIA and GEO databases showed that ASAP2 was highly expressed in pancreatic cancer tissues compared to normal pancreatic tissues and that high ASAP2 expression was associated with poorer tumour differentiation grade,overall survival(OS),disease-specific survival(DSS)and disease-free interval(PFI).The potential prognostic value of ASAP2 in pancreatic cancer was demonstrated by establishing a line graph from the clinical data in TCGA.Protein-protein-interactions(PPI),GO functional analysis and KEGG pathway enrichment analysis of ASAP2 co-expressed genes revealed that ASAP2 may be involved in cell junctional organisation,cell-matrix adhesion,regulation of chemotaxis,adhesion and regulation of PI3K-AKT signalling pathway.After knockdown and overexpression of ASAP2,cell phenotyping assays showed that ASAP2 could promote pancreatic cancer cell proliferation,migration,invasion,PI3K-AKT signalling pathway and EMT.miR-936 was also shown to target ASAP2 mRNA 3UTR and inhibit ASAP2 expression,thereby suppressing pancreatic cancer cell proliferation,migration,invasion,PI3K-AKT signalling pathway and EMT.proliferation,migration and invasive ability of pancreatic cancer cells.Finally,ASAP2 was negatively correlated with the enrichment of plasmacytoid dendritic cells(pDCs),CD8T cells and cytotoxic cells in pancreatic cancer tissues,positively correlated with Th2 cells,and negatively correlated with the abundance of chemokines or receptors such as CCL3,CCL4,CCL5,CCR4,CCR5 and CCR7 in tissues.Conclusions:High expression of ASAP2 is associated with poor prognosis in pancreatic cancer patients and is a potential prognostic biomarker and therapeutic target for pancreatic cancer,possibly associated with PC tumour immune cell infiltration.