RESUMO
Objective:By detecting the level changes of CXC chemokine ligand 8(CXCL8)in acute myelogenous leukemia(AML)patients at different disease stages,to analyze its correlation with the clinical condition and prognosis of AML patients,and to explore the effect of CXCL8 in the bone marrow microenvironment on the occurrence and development of AML and the regulatory mech-anism of malignant biological behavior of AML cell lines,to provide novel reference for the basic research and clinical diagnosis and treatment of AML.Methods:Bone marrow specimens from AML patients at different disease stages were collected,and ELISA was used to detect the content of CXCL8;quantitative real-time PCR(qRT-PCR)was used to detect the expression of CXCL8-specific receptor CXCR1/2 in different AML cell lines.U937 cells were selected as the AML disease model,and different concentrations of exogenous rCXCL8 were intervened in U937 cells,and the morphological changes of the cells were observed under the microscope.BM-MSCs from newly diagnosed AML patients were co-cultured with U937 cells,and ELISA was used to detect the difference in the content of CXCL8 in the co-culture system;Annexin V/PI double staining flow cytometry was used to detect the effects of rCXCL8 and anti-CXCL8 on the apoptosis of U937 cells respectively,and Western blot was used to reveal the accompanying molecular protein mechanism.Results:The level of CXCL8 in newly diagnosed and relapsed AML patients was significantly higher than that in healthy people(P<0.05),the level of CXCL8 in relapsed stage of AML was significantly higher than that in other disease stages of AML(P<0.01),and the level of CXCL8 in AML patients with CR stage and no infection was significantly higher than that in healthy people(P>0.05).The content of CXCL8 in the co-culture system of BM-MSC and U937 cells and the level of CXCL8 mRNA in U937 cells in the co-culture system were significantly higher than those in the monoculture group without BM-MSC(P<0.05).Intervention of rCXCL8 in U937 cells could promote cell proliferation by up-regulating Bcl-2 expression and down-regulating Bax expression,and up-regulate the expression of CXCL8-specific receptors CXCR1/2.After antagonizing CXCL8(anti-CXCL8),it will induce U937 cell apoptosis by up-regulating of Bax expression and down-regulating of Bcl-2 expression while inhibiting the activation level of ERK1/2 signaling pathway.Conclusion:CXCL8 is closely related to the disease and prognosis of AML,and is an effective monitoring indicator for disease pro-gression and prognosis evaluation of AML patients.CXCL8 in the bone marrow microenvironment is an important chemokine for malig-nant proliferation and immune escape of leukemia cells.By antagonizing CXCL8,U937 cells can be induced to undergo apoptosis,whose mechanism may be related to the expression changes of Bcl-2 family proteins and the inhibition of ERK1/2 signaling pathway activation.
RESUMO
CXC chemokine ligand 8 (CXCL8) is highly expressed in many human tumors including colorectal cancer, and it can promote the malignant progression of tumors. It was reported that M2 macrophages were abundant in colorectal cancer microenvironment, but whether CXCL8 affects the infiltration of M2 macrophages and its potential mechanism are not yet clear. The study aimed to investigate the effect of CXCL8 on M2 macrophage infiltration and chemotaxis in the colorectal cancer. Firstly, we analyzed the CXCL8 expression and immune cell infiltration in human colorectal cancer tissues from TCGA RNA-seq data. The expression of CXCL8 was verified by immunohistochemistry in tissues obtained from Shanxi Provincial Cancer Hospital. Then, Western blot and qRT-PCR were employed to detect CXCL8 expression in five colorectal cancer cell lines. THP-1 cells were allowed to differentiate into M2 macrophages via the phorbol myristate acetate (PMA) and IL-4 treatment, followed by detection of the chemotaxis of M2 macrophages towards HCT116, SW480 and CXCL8-HCT116, CXCL8-SW480 cell lines. HCT116 and SW480 cells were treated with interleukin 1β (IL-1β) to detect the expression of CXCL8, and co-cultured with M2 macrophages to analyze the chemotactic activity. The results revealed that the expression of CXCL8 was increased in pairs of CRC tissues versus normal adjacent tissues, and there were more M2 macrophage infiltration in cancer tissues with high expression of CXCL8. The mRNA and protein expression of CXCL8 in HCT116 and SW480 were increased after the IL-1β treatment (P < 0. 05). We confirmed that CXCL8 is a chemotactic factor for M2 macrophages by transwell assays (P<0. 05). In conclusion, CXCL8 in colorectal cancer cells can be induced by IL-1β in colorectal cancer cells and the upregulation of CXCL8 can promote the chemotaxis of M2 macrophages. The massive infiltration of M2 macrophages in colorectal cancer microenvironment may be related with the increased expression of CXCL8.