Suppression of GLI sensitizes medulloblastoma cells to mitochondria-mediated apoptosis.

Zhongxiao Lin,Hansong Sheng,Li Sheng Yu,Lin Yuan Si Ma,Shangyu Xu,Ming Cai,Sisi Li,Liuxun Hu,Nu Zhang

doi:10.1007/s00432-016-2241-1

Abstract

PurposeThe sonic hedgehog (SHH) signalling pathway plays the important role in medulloblastoma (MB). Altered GLI expression plays a key role in these processes, and the inhibition of GLI may be a good cancer-targeted therapy. This study aimed to investigate whether GANT61, a GLI inhibitor, may inhibit the SHH signalling pathway promoting cell mitochondria-mediated apoptosis and enhance cisplatin apoptosis antineoplastic therapy.MethodsIn our study, we determined the effect of GANT61-mediated inhibition of GLI in Daoy MB cells. Cells were treated with different concentrations of GANT61 alone or in combination with cisplatin. Cell proliferation was assessed with CCK-8 assays, and cell invasion and migration were performed using 8-µm transwell inserts. Cell apoptosis was assessed with flow cytometric analysis and rhodamine 123. qPCR was used to complete RNA experiments. Protein expression was assessed with Western blotting.ResultsThe GANT61 significantly inhibited cell proliferation. GANT61 decreased the cell migration and invasion, impairing these crucial steps in tumour progression. Cell apoptosis was significantly increased in Daoy cells. Rhodamine 123 assay showed that GANT61 could decrease the mitochondrial membrane potential promoting cell mitochondria-mediated apoptosis. GANT61 inhibited the expression of GLI and Bcl-2 at both the mRNA and protein levels and might affect the expression of Bax, caspase-3 and caspase-9 to promote cell intrinsic apoptosis. Furthermore, GANT61 could enhance cisplatin-induced apoptosis to decrease the IC50 value of cisplatin. Finally, data suggest that GANT61 could enhance cisplatin-induced apoptosis through promoting the expression of Bax, caspase-3 and caspase-9 protein levels.ConclusionOur data suggest that the SHH signalling pathway plays an important role in MB. GLI is an oncogenic transcription factor in the SHH pathway, and targeting GLI with GANT61 results in favourable antitumour activity and targeted therapy.

Highlights

Medulloblastoma (MB) is one of the most aggressive brain tumours in the paediatric patient and is characterized byJ Cancer Res Clin Oncol (2016) 142:2469–2478 high mortality and poor prognosis (Gerber et al 2014)
To elucidate whether cell proliferation was decreased in the presence of GANT61, Daoy cells were treated with different concentrations of GANT61 for 24 h
To see whether GANT61 treatment could induce apoptosis, normally growing Daoy cells were treated with different concentrations of GANT61

Summary

Introduction

Medulloblastoma (MB) is one of the most aggressive brain tumours in the paediatric patient and is characterized byJ Cancer Res Clin Oncol (2016) 142:2469–2478 high mortality and poor prognosis (Gerber et al 2014). Many patients have good prognosis; many of them suffer from considerable disability and morbidity (Moxon-Emre et al 2014; Rutkowski et al 2010). The sonic hedgehog (SHH) signalling pathway has an important role in embryonic development and in the regulation of a variety of cellular functions (Scales and de Sauvage 2009). Aberrant activation of SHH signalling has been implicated in several human cancers, including MB, basal cell carcinoma and pancreatic cancer (Ozgur et al 2015; Von Hoff et al 2009). The zinc finger transcription factor GLI, including GLI1 and GLI2, is considered a mediator of the SHH pathway in MB. To shed light on the role of GLI in MB, we screened for genes preferentially regulated by GLI in MB cells

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