Fig. 3.

GKN1 downregulates gastrin-induced expression of CCKBR, growth factor receptors, and NF-κB-related proteins. a, b Gastrin increased the expression of CCKBR, EGFR, p-c-Met, and c-Met in AGS and MKN1 cells, whereas GKN1 significantly decreased the expression levels of these proteins, even in the cells treated with gastrin. c GKN1 silencing in HFE-145 cells resulted in elevated expression of the CCKBR, EGFR, and c-Met proteins. d Gastrin enhanced the expression of p-p65 and slightly increased that of IKKα/β, although it did not affect the expression of p65 and IκB proteins. However, GKN1 reverted the expression of IκB and decreased the expression of IKKα/β, p-p65, and p65 proteins. Data shown are representative of at least three independent experiments. e A significant decline in mRNA expression of gastrin was observed in AGS and MKN1 cells stably expressing the GKN1 protein (P = 0.015 and P = 0.026, respectively). f Gastrin markedly enhanced CCKBR mRNA expression in AGS and MKN1 cells (P = 0.017 and P = 0.047, respectively), whereas GKN1 completely suppressed the increase in the CCKBR mRNA levels induced by gastrin in both cell lines (P = 0.028 and P = 0.024, respectively). Experiments were performed in triplicate. Data are reported as relative quantities, according to an internal calibrator using the 2^−ΔΔCT method [16]. A Student's t test (P < 0.05) was used to analyze the statistical difference in Gastrin or CCKBR mRNA expression between experimental groups