Chemokine CXCR4 regulates gastric cancer development through IL-6/STAT3 signaling pathway / 免疫学杂志

ABSTRACT

The objective of this study is to investigate the effect of chemokine CXCR4 on the apoptosis of gastric cancer cells through IL-6/STAT3 signaling pathway and to explore the related mechanisms.Fluorescence quantitative PCR and Western blot were performed to detect the mRNA and protein expression levels of the chemokine CXCR4 in human gastric cancer tissues and adjacent non-cancerous tissues(PCT).Next,CXCR4 knockdown and overexpression were achieved by transfecting SGC7901 gastric cancer cell line with lentiviral vectors.TUNEL staining was used to evaluate the apoptosis of SGC7901 cells,while MTT assay was employed to measure cell proliferation.Western blot was conducted to determine the expression of apoptosis-related proteins Bax and Bcl2.Further,enzyme-linked immunosorbent assay(ELISA)was employed to measure the secretion levels of inflammatory cytokines.Real-time fluorescent quantitative PCR(RT-PCR)was utilized to quantify the expression of IL-6 mRNA in the IL-6/STAT3 signaling pathway,and Western blot was performed to analyze the expression of STAT3-Ser727 protein.In addition,after knocking down CXCR4 in SGC7901 cells,IL-6/STAT3 signaling pathway agonist lipopolysaccharide(LPS)was transfected,while in CXCR4-overexpressing SGC7901 cells,IL-6/STAT3 signaling pathway inhibitors angoline or bruceantinol were transfected.Then TUNEL staining was used to assess cell apoptosis,and Western blotting was performed to examine the expression levels of apoptosis-related proteins Bax and Bcl2 in these cells.Data showed that the expression of immune chemokine CXCR4 was increased in gastric cancer tissues,as compared with adjacent non-cancerous tissues.Single-cell gel electrophoresis analysis indicated that knockdown or overexpression of CXCR4 do not induce DNA damage in SGC7901 cells.TUNEL staining,MTT cell proliferation assay and Western blotting demonstrated that knockdown of CXCR4 in SGC7901 cells promoted the apoptosis in SGC7901 cells,while overexpression of CXCR4 inhibited the apoptosis.ELISA showed that knockdown of CXCR4 in SGC7901 cells promotes the expression of pro-inflammatory factors IL-1β and TNF-α,while inhibited the expression of anti-inflammatory factors IL-10 and TGF-β.Conversely,overexpression of CXCR4 demonstrated opposite effects.Finally,the activation of the IL-6/STAT3 signaling pathway significantly reduced the apoptosis induced by knocking down CXCR4 in iSGC7901 cells,whereas the inhibition of IL-6/STAT3 signaling pathway can significantly suppressed the induction of SGC7901 cells proliferation induced by CXCR4 overexpress.In conclusion,immunochemokine CXCR4 regulates gastric cancer cell apoptosis and inflammatory cytokines secretion through IL-6/STAT3 signaling pathway.