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PLoS One. 2015 Mar 16;10(3):e0116390. doi: 10.1371/journal.pone.0116390. eCollection 2015.

Hedgehog signaling pathway is active in GBM with GLI1 mRNA expression showing a single continuous distribution rather than discrete high/low clusters.

Author information

1
National Institute of Biomedical Genomics, P.O. N.S.S. Kalyani, West Bengal 741251, India.
2
Bangur Institute of Neurology, 52/1A, S.N. Pandit Street, Bhawanipore, Kolkata 700098, India.
3
Institute of Post Graduate Medical Education and Research, 244 AJC Bose Road, Kolkata-700020, India.
4
Nil Ratan Sarkar Medical College and Hospital, 138, AJC Bose Road, Kolkata-700014, India.
5
Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States of America.

Abstract

Hedgehog (Hh) signaling pathway is a valid therapeutic target in a wide range of malignancies. We focus here on glioblastoma multiforme (GBM), a lethal malignancy of the central nervous system (CNS). By analyzing RNA-sequencing based transcriptomics data on 149 clinical cases of TCGA-GBM database we show here a strong correlation (r = 0.7) between GLI1 and PTCH1 mRNA expression--as a hallmark of the canonical Hh-pathway activity in this malignancy. GLI1 mRNA expression varied in 3 orders of magnitude among the GBM patients of the same cohort showing a single continuous distribution-unlike the discrete high/low-GLI1 mRNA expressing clusters of medulloblastoma (MB). When compared with MB as a reference, the median GLI1 mRNA expression in GBM appeared 14.8 fold lower than that of the "high-Hh" cluster of MB but 5.6 fold higher than that of the "low-Hh" cluster of MB. Next, we demonstrated statistically significant up- and down-regulation of GLI1 mRNA expressions in GBM patient-derived low-passage neurospheres in vitro by sonic hedgehog ligand-enriched conditioned media (shh-CM) and by Hh-inhibitor drug vismodegib respectively. We also showed clinically achievable dose (50 μM) of vismodegib alone to be sufficient to induce apoptosis and cell cycle arrest in these low-passage GBM neurospheres in vitro. Vismodegib showed an effect on the neurospheres, both by down-regulating GLI1 mRNA expression and by inducing apoptosis/cell cycle arrest, irrespective of their relative endogenous levels of GLI1 mRNA expression. We conclude from our study that this single continuous distribution pattern of GLI1 mRNA expression technically puts almost all GBM patients in a single group rather than discrete high- or low-clusters in terms of Hh-pathway activity. That is suggestive of therapies with Hh-pathway inhibitor drugs in this malignancy without a need for further stratification of patients on the basis of relative levels of Hh-pathway activity among them.

PMID:
25775002
PMCID:
PMC4361547
DOI:
10.1371/journal.pone.0116390
[Indexed for MEDLINE]
Free PMC Article

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