Fig 2: High expression of regulator of G protein signaling 4 was associated with poor prognosis in patients with gastric cancer. A: Differential expression of regulator of G protein signaling 4 (RGS4) in The Cancer Genome Atlas Stomach Cancer dataset (TCGA-STAD); B: Differential expression of RGS4 in the integrated analysis of TCGA-STAD and the Genotype-Tissue Expression dataset; C: High expression of RGS4 was associated with lower overall survival in TCGA-STAD dataset; D: The correlation between RGS4 and T stage, N stage, M stage, tumor-node-metastasis stage and tumor grade of gastric cancer (GC); E: Differential expression of RGS4 in GC and para-carcinoma normal tissues of our center’s patients; F: Representative immunohistochemistry images showing the expression of RGS4 in GC and para-carcinoma normal tissues (strong staining: +++; moderate staining: ++; weak staining: +; negative staining: -); G: Differences in protein expression levels of RGS4 between GC and para-carcinoma normal tissues; H: High expression of RGS4 was associated with lower overall survival in GC patients in our center. bP < 0.01, cP < 0.001. RGS4: Regulator of G protein signaling 4; GC: Gastric cancer.

Fig 3: Overexpression of regulator of G protein signaling 4 promoted the proliferation, migration, and invasion of gastric cancer cells in vitro. A: The interference efficiency of the lentiviral carrying regulator of G protein signaling 4 (RGS4) was validated by real-time quantitative polymerase chain reaction (left) and western blot (right) analysis (overexpressing RGS4); B: The proliferation of AGS cells with RGS4 overexpression was determined by cell counting kit-8 assays; C: The effects of RGS4 overexpression on the colony formation of AGS cells; D: The migration ability of AGS cells was measured by wound healing; E: The invasion of AGS cells with RGS4 overexpression was determined by transwell assays. aP < 0.05, bP < 0.01, dP < 0.0001, NS: No significance. RGS4: Regulator of G protein signaling 4.

Fig 4: Knocking down regulator of G protein signaling 4 in gastric cancer cells inhibited tumor growth in vivo. A-F: Tumors from MGC-803 cells with regulator of G protein signaling 4 (RGS4) knockdown and AGS cells with RGS4 overexpression and their controls (n = 5/groups) (A and D), tumor growth curves (B and E), tumor weight of each group (C and F); G: The expression of focal adhesion kinase/phosphatidyl-inositol-3-kinase/protein kinase B pathway and epithelial mesenchymal transition related proteins in MGC-803 cells and AGS cells in vivo were validated by western blot. β-actin was used as a loading control; H: The expression of RGS4, Ki67 and p-AKT in these xenografts via immunohistochemistry staining; I: Schematic diagram of the mechanism of RGS4 promoting gastric cancer progression. bP < 0.01, cP < 0.001, dP < 0.0001. FAK: Focal adhesion kinase; PI3K: Phosphatidyl-inositol-3-kinase; AKT: Protein kinase B; RGS4: Regulator of G protein signaling 4; PIP: Prolactin-induced protein; mTOR: Mechanistic target of rapamycin.