Combination of hTERT Knockdown and IFN-y Treatment Inhibited Angiogenesis and Tumor Progression in Glioblastoma

Purpose: The limitless invasive and proliferative capacities of tumor cells are associated with telomerase and expression of its catalytic component, human telomerase reverse transcriptase (hTERT). IFN-y modulates several cellular activities, including signaling pathways and cell cycle, through transcriptional regulation. Experimental Design: Using a recombinant plasmid with hTERT siRNA cDNA, we downregulated hTERT during IFN-y treatment in human glioblastoma SNB-19 and LN-18 cell lines and examined whether such a combination could inhibit angiogenesis and tumor growth in nude mice. In vitro angiogenesis assay was done using coculture of tumor cells with human microvascular endothelial cells. In vivo angiogenesis assay done using diffusion chambers under the dorsal skin of nude mice. In vivo imaging of intracerebral tumorigenesis and longitudinal solid tumor development studies were conducted in nude mice. Results: In vitro and in vivo angiogenesis assays showed inhibition of capillary-like network formation of microvascular endothelial cells and neovascularization under dorsal skin of nude mice, respectively. We observed inhibition of intracerebral tumorigenesis and s.c. solid tumor formation in nude mice after treatment with combination of hTERT siRNA and IFN-y. Western blotting of solid tumor samples showed significant clownregulation of the molecules that regulate cell invasion, angiogenesis, and tumor progression. Conclusions: Our study showed that the combination of hTERT siRNA and IFN-y effectively inhibited angiogenesis and tumor progression through the clownregulation of molecules involved in these processes. Therefore, the combination of hTERT siRNA and IFN-y is a promising therapeutic strategy for controlling the growth of human glioblastoma. (Clin Cancer Res 2009;15(23):7186-95)