Abstract 146: The long noncoding RNA MALAT1 promotes hypoxia-driven angiogenesis by upregulating pro-angiogenic gene expression in neuroblastoma cells

Neuroblastoma is the most common solid tumour during early childhood, and accounts for 15% of all childhood cancer death. One of the key features of neuroblastoma is aggressive progression due to tumour-driven angiogenesis. However, the mechanism through which neuroblastoma cells drive angiogenesis is unclear. Here we showed that the long noncoding RNA MALAT1 was over-expressed in human neuroblastoma cells under hypoxic condition, the condition which triggers pro-angiogenic switch and angiogenesis. In vitro angiogenesis assays demonstrated that conditioned medium from neuroblastoma cells transfected with MALAT1 siRNAs, compared with conditioned medium from neuroblastoma cells transfected with control siRNAs, induced considerably less endothelial cell migration, invasion and vascular sprouting under hypoxic condition. Affymetrix microarray differential gene expression study showed that one of the genes most significantly down-regulated by MALAT1 siRNAs in human neuroblastoma cells under hypoxic condition, was fibroblast growth factor (FGF). RT-PCR and immunoblot analyses confirmed that MALAT1 siRNAs reduced FGF mRNA and protein expression, and in vitro angiogenesis assays demonstrated that forced over-expression of FGF in neuroblastoma cells blocked MALAT1 siRNA-mediated reduction in endothelial cell migration, invasion and vascular sprouting. Taken together, our data suggest that over-expression of MALAT1 in human neuroblastoma cells plays an important role hypoxia-driven angiogenesis by up-regulating FGF mRNA expression. Citation Format: Andrew E. Tee, Peiyan Liu, Jesper Maag, Renhua Song, Jinyan Li, Belamy B. Cheung, Michelle Haber, Murray D. Norris, Glenn M. Marshall, Marcel Dinger, Tao Liu. The long noncoding RNA MALAT1 promotes hypoxia-driven angiogenesis by upregulating pro-angiogenic gene expression in neuroblastoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 146. doi:10.1158/1538-7445.AM2015-146