N-methyl-N-nitro-N′-nitrosoguanidine induces the expression of CCR2 in human gastric epithelial cells promoting CCL2-mediated migration

Chronic inflammation has a decisive role in tumorigenesis, particularly in gastric carcinogenesis. The CC chemokine ligand 2 (CCL2), an important inflammatory cytokine, is involved in the initiation, development and progression of various types of cancer. However, the role of CCL2 in gastric cancer remains to be elucidated. The present study demonstrated that recombinant CCL2 stimulation caused no effect on the morphology, proliferation and migration of human GES-1 gastric mucosa epithelial cells, in which the protein expression of CC-chemokine receptor 2 (CCR2) was markedly low. However, the expression of CCR2 was significantly upregulated in the GES-1 cells following pretreatment with the chemical carcinogen, N-methyl-N-nitro-N'-nitrosoguanidine (MNNG), for 12 h or transformed with MNNG (MC cells). The present study used CCL2 to stimulate MNNG pretreated GES-1 cells and MC cells, and demonstrated that CCL2 clearly promoted their migration and the epithelial-mesenchymal transition (EMT). However, no effect was observed on the proliferative ability of the cells. Taken together, these findings suggested that the CCL2/CCR2 chemokine signaling may regulate the EMT in gastric epithelial cells and resulted in gastric carcinogenesis in response to the intake of the carcinogen, MNNG.