We developed a RET mini-gene reporter system, and showed that MCS+9.7 enhanced HOXB5 trans-activation from RET promoter in human neuroblastoma SK-N-SH cells and in chick embryos.
Taken together these data suggest that abnormalities of the RET signalling pathway, rather than oncogenic, MEN2-type RET activation by mutation, may play a role in neuroblastoma tumorigenesis.
Taken together, these results indicate that GDNF up-regulates the expression of the TH gene by promoting the transcription of the TH gene and the stability of TH mRNA with the Ret receptor dependency in some neuroblastoma cell lines.
In summary, our study suggests that RET is a potential therapeutic target in NB, and that using a novel RET inhibitor, like regorafenib, should be investigated as a therapeutic treatment option for children with NB.
In the present work, we have studied the ability of GDNF proteins, each bearing one of the reported mutations, to activate RET by performing a functional test in cultured neuroblastoma cells.
Furthermore, there is strong evidence against linkage to two Hirschsprung disease (a condition that can cosegregate with neuroblastoma) susceptibility genes, RET and EDNRB.
We have also demonstrated by the in vitro premethylation of a RET promoter-chloramphenicol acetyltransferase (CAT) gene construct and transient transfection experiments into neuroblastoma cells that the transcriptional activity of the RET promoter is decreased by HpaII (5'-CCGG-3') methylation and abolished by SssI (5'-CG-3') methylation.
Transfection experiments using human neuroblastoma cells showed that the mutant RET, unlike the wild-type receptor, is constitutively phosphorylated in the absence of ligand, and thus resembles other previously characterized MEN 2A mutations.