Role of ADP Ribosylation Factor Guanylate Kinase 1 in the Malignant Biological Behavior of Gastric Cancer

Abstract Objectives: To study the effects of ADP ribosylation factor guanylate kinase 1 gene (ASAP1) on the biological behavior of malignant gastric cancer (GC), and explore its possible molecular mechanisms in tumorigenesis and tumor progression.Methods: Quantitative PCR and western blotting (WB) were performed to measure ASAP1 mRNA and protein expression in the GES-1 epithelial cell line, which is derived from normal human mucosa, and three GC cell lines. Molecular biology techniques such as lentivirus packaging, infection, and screening were used to obtain BGC823 GC cells overexpressing ASAP1 and BGC823 and MKN45 cells with ASAP1 knocked down. The Cell Counting Kit-8 assay, colony formation assay, flow cytometry using Annexin V/propidium iodide, Transwell migration and invasion assays, and scratch assay were used to assess the malignant biological behavior of GC cells with ASAP1 overexpression and knockdown. WB was conducted to evaluate the effects of ASAP1 expression on angiogenesis, as well as on the expression of matrix metalloproteinases (MMPs), apoptotic proteins, and epithelial-mesenchymal transition (EMT)-related proteins. Nude mice bearing transplanted tumors were evaluated to determine the effect of ASAP1 knockdown on BGC823 GC cells.Results: ASAP1 expression in GC cells was greater than that in GES-1 normal gastric mucosal epithelial cells. ASAP1 overexpression significantly enhanced the proliferation, invasion, and migration of GC cells and reduced apoptosis; whereas ASAP1 knockdown significantly reduced the proliferation, invasion, and migration of GC cells and promoted apoptosis. In the ASAP1-knockdown group, expression of cleaved-caspase 3, cleaved-poly-ADP-ribose polymerase (PARP), and the epithelial marker E-cadherin increased significantly, whereas the expression of MMP2, MMP9, vascular endothelial growth factor A (VEGFA), and the mesenchymal markers N-cadherin, and vimentin decreased significantly (P<0.01). Knockdown of ASAP1 inhibited the growth of subcutaneously implanted tumors in nude mice.Conclusions: ASAP1 overexpression strongly promotes—whereas knockdown of ASAP1 effectively weakens—the malignant biological behavior of GC cells, possibly by reducing VEGFA expression and thus reducing angiogenesis, upregulating the expression of cleaved-caspase 3 and cleaved-PARP, and reducing the activity of MMPs and EMT.