Suppression of CD74 expression and Helicobacter pylori adhesion by auraptene targeting serum starvation-activated ERK1/2 in NCI-N87 gastric carcinoma cells.

Helicobacter pylori (H. pylori) is a major human pathogen and plays a central role in chronic gastritis and gastric cancer. Since the adhesion of H. pylori to the human gastric epithelium is the initial and critical step of its infection, anti-H. pylori adhesion agents may be effective for the prevention and therapy of H. pylori-associated diseases. CD74 has recently been identified as a new receptor for H. pylori urease, and we have previously reported that several citrus components strongly suppressed CD74 expression in NCI-N87 gastric carcinoma cells. We found in this present study that auraptene (citrus coumarin) disrupted serum starvation-induced extracellular signaling-regulated kinase (ERK) 1/2 activation and attenuated H. pylori adhesion and IL-8 production in a co-culture system. In addition, the knockdown of CD74 expression led to a significant decrease of H. pylori adhesion, but unexpectedly increased IL-8 production. However, PD98059 (a MEK1/2 inhibitor) dramatically down-regulated this cytokine, suggesting MEK/ERK-dependent IL-8 production. Our results suggest that auraptene suppressed H. pylori adhesion and resulting chemokine production by disrupting ERK1/2 activation.