Activation of Sonic Hedgehog Signaling Pathway in Olfactory Neuroblastoma

Abstract

Objectives: Sonic hedgehog (Shh) signaling pathway is associated with tumor development; however, the role of Shh signaling in the development of olfactory neuroblastoma (ONB) is unknown. This study aimed to investigate the relationship between the regulation of Shh signaling and the pathogenesis of ONB. Methods: The expression of Shh signaling components was characterized by immunohistochemistry in human non-tumor olfactory epithelium and ONB specimens, and by RT-PCR and immunoblotting in human ONB cell lines. The impact of the treatment with cyclopamine (a selective inhibitor of the Shh pathway) and/or exogenous Shh on ONB cell proliferation, cycle and apoptosis was examined by MTT, soft agar colony formation and flow cytometry assays, respectively. The influence of Shh signaling on the expression of Shh signaling components and cell cycle-related regulators was determined by immunoblotting and quantitative RT-PCR, respectively. Results: The expression of Pacthed1, Gli1 and Gli2 was detected in 70, 70, and 65% of human ONB specimens, respectively, and in proportion of ONB cell lines, but not in non-tumor olfactory epithelium. Treatment with cyclopamine inhibited the proliferation and colony formation of ONB cells, induced ONB cell cycle arrest and apoptosis, and down-regulated the expression of Pacthed1, Gli1 and cyclin D1, but up-regulated p21 expression in vitro. These regulatory effects of cyclopamine were partially or completely erased by exogenous Shh. Conclusion: These data suggest that the Shh signaling pathway is crucial for the growth of ONB.

Evaluation of NKX2-2 expression in round cell sarcomas and other tumors with EWSR1 rearrangement: imperfect specificity for Ewing sarcoma

“…Given that EWSR1-FLI1 promotes NKX2-2 expression by upregulating GLI1, 30 NKX2-2 positivity in olfactory neuroblastomas may be explained by tumoral activation of sonic hedgehog signaling. 31 Mesenchymal chondrosarcomas, characterized by HEY1-NCOA2 gene fusion, 32 demonstrated immunoreactivity for NKX2-2 in 33% of cases in a prior study 11 and, in this study, …”

Expression and epigenetic modulation of sonic hedgehog-GLI1 pathway genes in neuroblastoma cell lines and tumors

“…Taken together, our results lead us to assume that sonic hedgehog signaling is activated in neuroblastoma, although few studies support a role for Shh signaling in the tumorigenesis of neuroblastoma [48,66]. In our study, we were able to determine some of the target genes of Shh- Sample NT-1 shows unmethylation (a), NT-8 shows hemi-methylation (b), and NT5 shows methylation (c) in the HHIP promoter region GLI1 signaling.…”

Genetic and molecular alterations in olfactory neuroblastoma: implications for pathogenesis, prognosis and treatment

“…Experimental studies demonstrated the Sonic hedgehog signaling pathway (Shh) being activated in ONB [78]. The influence of Shh signaling on the expression of its signaling components and cell cycle-related regulators was determined by immunoblotting and quantitative RT-PCR.…”