RNA interfering of CXCR4 inhibits the adhesion, invasion, and tumorigenicity of acute monocytic leukemic cells in vivo

To investigate the effect of CXCR4 gene expressing on the proliferation, adhesion, and invasion of human monocytic leukemic cell line SHI-1 and its tumorigenic capacity in nude mouse. The SHI-1 cells were firstly infected with the rescued recombinant lentivirus to establish SHI-1/CXCR4i cell line. The expression of CXCR4, MMP-2 and MMP-9 in the SHI-1/CXCR4i cell was determined by real time quantitative PCR and flow cytometry. MTT assay was performed to detect the SHI-1/CXCR4i cell proliferative rate. The co-culture system of the leukemia cells with bone marrow stromal cells was utilized to detect the adhesive and migratory ability of SHI-1/CXCR4i cell. The nude mouse was subcutaneously inoculated with both cell lines, and then used to evaluate the growth ability of leukemia cells without CXCR4 expressing. The expression of CXCR4 mRNA in established SHI-1/CXCR4i cells decreased by 76% comparing with that in SHI-1/NC cells, which were infected with negative control virus. The proliferative rate of the SHI-1/CXCR4i cells in vitro did not show obvious difference with the SHI-1/NC cells, however, the adhesive and trans-Matrigel invasive ability were significantly decreased. Notably, the neoplasm was not observed in mice subcutaneously inoculated with SHI-1/CXCR4i cells, but presented in the SHI-1/WT and SHI-1/NC cells-inoculated mice in neoplastic volume of both groups. The present data showed that the CXCR4 silencing reduced the adhesive and migratory ability of SHI-1 cells in vitro, and suppressed the formation of subcutaneous neoplasm in vivo, demonstrating that the CXCR4 can be served as a novel target for leukemia gene therapy.