Complementary action of CXCL1 and CXCL8 in pathogenesis of gastric carcinoma

Chemokine (C-X-C motif) ligand (CXCL) is a class of secreted growth factor that signals through a G-protein coupled receptor. CXCL protein family members play important roles in inflammation and aberrant expression is associated with growth and progression of certain tumors. To explore the expression pattern and action mechanism of CXCL1 and CXCL8 in development of gastric carcinoma (GC), 72 cases of GC and para-carcinoma tissue specimens were used for experimental study, and qPCR was used for analysis on the expression of CXCL1 and CXCL8 in GC specimens. For in vitro culture of GC cell HGC27, knockout of CXCL1 and CXCL8 genes for GC cell HGC27 was performed through RNA interference, proliferation of HGC27 cells was tested by MTT, apoptosis of HGC27 cells was tested by flow cytometry, and the influence of CXCL1 and CXCL8 on HGC27 cell migration was tested by transwell. CXCL1 and CXCL8 expression level in HGC27 cells was analyzed by Western blotting. Co-immunoprecipitation (co-IP) was used for identifying interaction of CXCL1 and CXCL8 with CXCR2 in GC cells. The results show that both CXCL1 and CXCL8 expression were significantly up-regulated. Relevant clinical data showed that low expression of CXCL1 and CXCL8 significantly correlated with features for poor prognosis of GC, including serum alpha-fetoprotein (AFP) level, tumor size, and TNM staging. Down-regulation of CXCL1 and CXCL8 may up-regulate expression of each other and thus silencing expression of CXCL1 and CXCL8 may significantly inhibit proliferation and migration capabilities of HGC27 cells, and induce the apoptosis. Downregulated CXCL1 and CXCL8 expression in GC cells may significantly intensify interaction of one another and with CXCR2. The above results indicate that CXCL1 and CXCL8 participate in GC proliferation, apoptosis, and migration processes through specific binding with CXCR2 by a synergistic effect.