The long noncoding RNA MALAT1 promotes tumour-driven angiogenesis by up-regulating pro-angiogenic gene expression (14215)
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 disease 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-mediated 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 in tumour-driven angiogenesis by up-regulating FGF mRNA expression.