Chemokine receptor CXCR3 promotes growth of glioma

Abstract

Human glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The poor prognosis and minimally successful treatments of GBM indicates a need to identify new therapeutic targets. In this study, we examined the role of CXCR3 in glioma progression using the GL261 murine model of malignant glioma. Intracranial GL261 tumors express CXCL9 and CXCL10 in vivo. Glioma-bearing CXCR3-deficient mice had significantly shorter median survival time and reduced numbers of tumor-infiltrated natural killer and natural killer T cells as compared with tumor-bearing wild-type (WT) mice. In contrast, pharmacological antagonism of CXCR3 with NBI-74330 prolonged median survival times of both tumor-bearing WT and CXCR3-deficient mice when compared with vehicle-treated groups. NBI-74330 treatment did not impact tumor infiltration of lymphocytes and microglia. A small percentage of GL261 cells were identified as CXCR3(+), which was similar to the expression of CXCR3 in several grade IV human glioma cell lines (A172, T98G, U87, U118 and U138). When cultured as gliomaspheres (GS), the human and murine lines increased CXCR3 expression; CXCR3 expression was also found in a primary human GBM-derived GS. Additionally, CXCR3 isoform A was expressed by all lines, whereas CXCR3-B was detected in T98G-, U118- and U138-GS cells. CXCL9 or CXCL10 induced in vitro glioma cell growth in GL261- and U87-GS as well as inhibited cell loss in U138-GS cells and this effect was antagonized by NBI-74330. The results suggest that CXCR3 antagonism exerts a direct anti-glioma effect and this receptor may be a potential therapeutic target for treating human GBM.