IL-8 is a mediator of NF-κB induced invasion by gliomas.
Glioblastoma (GBM) is the most common and deadly form of primary brain tumor with a median survival of eleven months, despite use of extensive chemotherapy, radiotherapy and surgery. We have previously shown that nuclear factor-kappa B (NF-κB) is aberrantly expressed in GBM tumors and primary cell lines derived from tumor tissue. Here we show that IL-8, a chemokine is also aberrantly expressed by GBM cell lines and expression of IL-8 is in large part, attributable to the aberrant activation of NF-κB. We hypothesized that invasiveness of GBM cells is driven at least in part by aberrantly expressed IL-8. In support of the hypothesis we found that treatment of glioma cells with an IL-8 neutralizing antibody markedly decreased their invasiveness compared to cells treated with control IgG or left untreated. Furthermore, downregulation of IL-8 protein production with use of IL-8 targeted siRNA also resulted in decreased invasion in matrigel. We next investigated the presence of IL-8 receptors by FACS analysis and found that GBM cells (U87, U251, D54 and LN229) only express CXCR1 but not CXCR2. Treatment of U87 cells with a blocking CXCR1 antibody reduced their invasion through matrigel. Finally, we found that addition of exogenous IL-8, following downregulation of NF-κB which results in loss of endogenous IL-8 production, incompletely restored tumor cell invasion. Our data indicate that IL-8 is necessary but not solely responsible for glioma cell invasion and mediates its effect in an autocrine manner.
Raychaudhuri
Baisakhi
B
Brain Tumor and Neuro-Oncology Center, Neurological Institute, Cleveland Clinic, 9500 Euclid Avenue ND40, Cleveland, OH 44195, USA.
Vogelbaum
Michael A
MA
D000906:Antibodies / Q000494:pharmacology; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005434:Flow Cytometry / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D018014:Gene Transfer Techniques; D005909:Glioblastoma / Q000473:pathology; D006801:Humans; D016209:Interleukin-8 / Q000276:immunology / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D034741:RNA, Small Interfering / Q000494:pharmacology; D023062:Receptors, Interleukin-8A / Q000276:immunology / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000276:immunology / Q000378:metabolism; D013997:Time Factors
D000906:Antibodies; D016209:Interleukin-8; D016328:NF-kappa B; D034741:RNA, Small Interfering; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B