The activation of SYNJ2/GRB2 axis accelerates the malignant metastasis and angiogenesis of gastric cancer cells

Abstract

In gastric cancer (GC), tumor cell metastasis to lymph node may occur, and can be impacted by synaptojanin 2 (SYNJ2). Herein, we explored the mechanism of SYNJ2 in the progress of GC. SYNJ2 level in GC tissues was predicted by GEPIA database. After GC cells were transfected with short hairpin RNA against SYNJ2 (shSYNJ2), shGRB2, SYNJ2 overexpression plasmid and growth factor receptor-bound protein 2 (GRB2) overexpression plasmid, the mRNA levels of SYNJ2 and GRB2 in GC cells were quantified by qRT-PCR. CCK-8, flow cytometry, wound healing, transwell and tube formation assays were performed for detecting viability, apoptosis, migration, invasion and angiogenesis of GC cells. Protein levels of GRB2, vascular endothelial growth factor (VEGF), E-Cadherin, N-Cadherin and Vimentin in GC cells were measured by Western blot. The relationship between SYNJ2 and GRB2 was assessed by Co-immunoprecipitation (CO-IP) assay. SYNJ2 was highly expressed in GC tissues and cells. SYNJ2 overexpression promoted viability, migration, invasion, angiogenesis and GRB2 level, and inhibited apoptosis of GC cells, while shSYNJ2 exhibited opposite effects. GRB2 overexpression boosted yet shGRB2 suppressed cell migration, invasion and angiogenesis. Notably, SYNJ2 could interact with GRB2. GRB2 overexpression and shGRB2 reversed the effects of shSYNJ2 and overexpressed SYNJ2 on cell migration, invasion and angiogenesis and levels of metastasis-related proteins, respectively. In conclusion, SYNJ2 promotes GC cell metastasis and angiogenesis by up-regulating GRB2.