The chemokine stromal cell derived factor-1 (CXCL12) promotes glioma invasiveness through MT2-matrix metalloproteinase

Chemokines have been found to alter tumor growth and metastasis. We have described previously that a particular chemokine receptor, CXCR4, was predominantly expressed on various glioma cell lines and in resected glioblastoma specimens. Herein, we have tested the ligand of CXCR4, stromal cell derived factor-1 alpha (SDF-1 alpha, CXCL12), on the response of human glioma cells. We found that SDF-1 alpha increased the expression of membrane type-2 matrix metalloproteinase (MT2-MMP), but not the other MT-MMPs, MMP-2 or MMP-9. The SDF-1 alpha enhanced MT2-MMP expression was blocked by a CXCR4 antagonist, AMD3100. Functional invasion assays showed that SDF-1 alpha stimulated glioma cells to invade through matrigel-coated chambers and this effect was inhibited in glioma cells by the stable downregulation of MT2-MMP expression using small interfering RNA (siRNA). In vivo and at asymptomatic stages following intracerebral implant of cells, mice harboring MT2-MMP siRNA downregulated clones had smaller and less invasive tumors compared with mice implanted with non-specific siRNA control cells. Analyses at symptomatic stages demonstrate that mice with MT2-MMP siRNA clones survive longer than mice harboring control cells. These results highlight MT2-MMP as an effector of CXCR4 signaling in glioma cells, and they reveal the novel role of MT2-MMP in modulating tumor activity.