Direct contact with bone marrow stromal cells promotes the invasions of SHI-1 leukemia cells

摘要

Background Interactions of tumor cells with the microenvironment were deemed to promote the tumor invasion and metastasis.CXC chemokine receptor 4 (CXCR4) and extracellular matrix metalloproteinase inducer (EMMPRIN) had reported to participate in this process.However the roles of bone marrow microenvironment in leukemic infiltration were not well investigated.Methods A co-culture system between SHI-1 cells and bone marrow stromal cells (BMSCs) is used to simulate the interactions of leukemic ceils with their microenvironment.The trans-matrigel invasion was used to detect the capability of SHI-1 cells invasion.The BMSCs and SHI-1 cells were mixed in a ratio of 1:10 and added to the millicell chamber coated with matrigel.Either the co-culture supernatant or the functional blocking peptide of CXCR4 and EMMPRIN were added to the trans-matrigel invasion system.The expressions of EMMPRIN in SHI-1 cells and BMSCs were detected by RT-PCR.The changes of the expression of matrix metalloproteinase-2,9 (MMP-2,MMP-9),tissue inhibitor of metalloproteinase 2 (TIMP-2),and CXCR4 mRNA in SHI-1 cells were determined by real-time PCR.The concentration of stromal cell derived factor 1 (SDF-1) in serum free supernatant was measured by ELISA.Results Both SHI-1 cells and BMSCs express EMMPRIN.SHI-1 ceils could hardly invade the matdgel membrane; the coculture supernatant did not induce the invasion of SHI-1 cells.When contacting directly with BMSCs,SHI-1 cells invaded to the lower chamber of millicell were significantly increased.The functional blocking peptide of CXCR4 and EMMPRIN could significantly inhibit the invasion triggered by BMSCs.When co-culturing with BMSCs,the expression of CXCR4,MMP-2,MMP-9 and TIMP-2 mRNA in SHI-1 cells were significantly elevated in company with a significantly higher level of SDF-1 in the co-cultured serum-free supernatant.Conclusion The interactions of leukemic cells and BMSCs play important roles in leukemic cell infiltration.