Characterization and application of two novel monoclonal antibodies against human CXCR4: cell proliferation and migration regulation for glioma cell line in vitro by CXCR4/SDF-1alpha signal.

CXCR4/SDF-1 alpha signal is essential for cell development, hematopoiesis, organogenesis, and vascularization as well as leukocyte trafficking. Many published reports have highlighted CXCR4 as a target in HIV infection and in cancer metastasis. In this study, we generated two specific monoclonal antibodies (MAbs 6H7 and 7D4) against human CXCR4 and found that they could recognize different antigen epitopes identified by 12G5, a commercially available anti- CXCR4 MAb. With the two MAbs, we detected the expression pattern of CXCR4 on T lymphocytes and human tumor cell lines by FCM (flow cytometry), as well as glioma tissues by immunohistochemical staining. The results showed widespread CXCR4 expression patterns in tumor cell lines and tissues and an inducible expression in CD4(+) T lymphocytes. Furthermore, we demonstrated that both of the MAbs have different functions on glioma cell line proliferation and migration in vitro. MAb 6H7 could synergistically enhance glioma cell line U251 cell proliferation induced by SDF-1 alpha, while MAb 7D4 showed a blocking effect. Despite the difference in proliferation, both antibodies could attenuate chemotaxis of U251 cell induced by SDF-1 alpha. Taken together, the two novel antibodies may be of great value to explore the mechanisms of SDF-1 alpha CXCR4 signal in tumor cells metastasis.