Expression Of CXCR7 In Acute Monocytic Leukemia And Its Effects On THP-1 Cell Functions

Objective To study the expression of stromal cell derived factor-1?(SDF-1?)receptor CXCR7 in acute monocytic leukemia(AML-M5)and its effects on proliferation,apoptosis,invasion of acute monocytic leukemia cell line THP-1.Methods Periheral blood samples were collected from 10 patients with AML at the time of diagnosis and also,10 healthy individuals.Periheral blood mononuclear cells(PBMC)were isolated by Ficoll density gradient centrifugation.Acute monocytic leukemia line THP-1 cells was cultured in vitro.(1)Flow cytometry was used to detect the expression of CXCR7 on THP-1 cells and immature cells from patients newly diagnosed AML-M5 and normal persons.(2)CXCR7 protein expression levels in THP-1 cells,PBMC from AML-M5 patients and normal human were detected by Western Blot.(3)CXCR7 m RNA expression levels were detected by RT-PCR.(4)CCK8 was used to observe the effects of CXCR7 on the proliferation.Cell proliferation was observed in vitro after blocked the expression of CXCR7 on surface of THP-1 cells by CXCR7 monoclonal antibody 11G8.(5)Annexin V/PI double staining was used to observe the effects of CXCR7 monoclonal antibody on the apoptosis of THP-1 cells in serum-free culture.(6)Transwell assay was used to observe the effects of CXCR7 on the invasion.Cell invasion was observed after CXCR7 antibody blocked the expression of CXCR7 on the surface of THP-1 cells.Results(1)The expression of CXCR7 on immature cell surface of the newly diagnosed AML-M5 patients was higher than that in the control group(P<0.05).CXCR7 was alsohighly expressed on THP-1 cells surface.(2)The CXCR7 protein level in THP-1 cells and PBMC of AML-M5 were higher than that in the control group(P<0.05).(3)The CXCR7 m RNA level in THP-1 cells and PBMC of AML-M5 were higher than that in the control group(P<0.05).(4)The THP-1 cells proliferation activity was higher in SDF-1? treated group.But this activity could be inhibited by CXCR7 antibody(P<0.01).(5)CXCR7 antibody did not affect apoptosis of THP-1 cells in serum-free culture(P>0.05).(6)SDF-1?/CXCR7 chemotaxis axis promotes invasion of THP-1 cells in vitro.CXCR7 antibody can inhibit SDF-1?-induced THP-1 cells invasiveness(P<0.01).Conclusion(1)CXCR7 levels were higher in acute monocytic leukemia patients and THP-1 cells,but it was hardly expressed in normal controls.(2)SDF-1?/CXCR7 chemotaxis axis promotes proliferation activity of THP-1 cells.Blocking the interaction between CXCR7 and SDF-1? can effectively reduce the proliferation of THP-1 cells by using CXCR7 monoclonal antibody 11G8.(3)Under serum-free culture conditions,the apoptotic activity of THP-1 cells was not affected by CXCR7 monoclonal antibody.(4)SDF-1?/CXCR7 chemotaxis axis promotes invasion of THP-1 cells in vitro.The most effective way to reduce SDF-1? induced invasion ability of THP-1 cells was to use CXCR4 and CXCR7 block agents at the same time.