Fig. 4: SPARC is a pivotal downstream target of LCN2 in GC.

A Volcano plot showing the differential expression genes in negative control and LCN2 knockdown MKN1 cells. The x-axis represents the fold changes of read density and the y-axis shows the adjusted p value. B, C Detection of SPARC mRNA (B) and protein (C) levels in GC cells with LCN2 overexpression or knockdown using RT-qPCR and western blot. D IHC images of SPARC expression in xenograft tumor tissues with LCN2 overexpression and the negative control. Scale bar: 50 μm. E, F Promotion of the proliferation and metastasis ability of MKN1 (E) and AGS (F) cells by SPARC overexpression, as assessed by CCK-8 assay and transwell assay. G, H Inhibition of the proliferation and metastasis ability of MKN1 (G) and AGS (H) cells by SPARC knockdown, as assessed by CCK-8 assay and transwell assay. I Increase in SPARC protein level following LCN2 knockdown, which was rescued by SPARC siRNAs. Protein levels were measured by western blotting assay (left panel), and the grayscale was measured by ImageJ software. J CCK-8 and transwell assays showing that the proliferation and metastasis ability increased upon LCN2 knockdown, and this effect was rescued by SPARC knockdown. K Transfection of SPARC-overexpressed plasmids and the corresponding controls into LCN2-overexpressed AGS cells. Protein levels were measured by western blotting (left panel), and the grayscale was measured by ImageJ software. L CCK-8 and transwell assays revealed that SPARC overexpression rescued the suppression of proliferation and metastasis ability caused by LCN2 overexpression. Data are presented as mean ± SD of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001.