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The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling
BACKGROUND: The crosstalk between Hedgehog (HH) signaling and other signal transduction cascades has been extensively studied in different cancers. In neuroblastoma, mTOR/S6K1 signaling is known to have a role in the development of this disease and recent evidence also implicates the HH pathway. Mor...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4152578/ https://www.ncbi.nlm.nih.gov/pubmed/25134527 http://dx.doi.org/10.1186/1471-2407-14-600 |
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author | Diao, Yumei Rahman, Mohammed Ferdous-Ur Villegas, Victoria E Wickström, Malin Johnsen, John I Zaphiropoulos, Peter G |
author_facet | Diao, Yumei Rahman, Mohammed Ferdous-Ur Villegas, Victoria E Wickström, Malin Johnsen, John I Zaphiropoulos, Peter G |
author_sort | Diao, Yumei |
collection | PubMed |
description | BACKGROUND: The crosstalk between Hedgehog (HH) signaling and other signal transduction cascades has been extensively studied in different cancers. In neuroblastoma, mTOR/S6K1 signaling is known to have a role in the development of this disease and recent evidence also implicates the HH pathway. Moreover, S6K1 kinase has been shown to phosphorylate GLI1, the effector of HH signaling, promoting GLI1 transcriptional activity and oncogenic function in esophageal adenocarcinoma. In this study, we examined the possible interplay of S6K1 and GLI1 signaling in neuroblastoma. METHODS: siRNA knockdowns were used to suppress S6K1 and GLI1 expression, and the siRNA effects were validated by real-time PCR and Western blotting. Cell proliferation analysis was performed with the EdU incorporation assay. Cytotoxic analysis with increasing concentrations of PI3K/mTOR and GLI inhibitors, individually and in combination, was used to determine drug response. RESULTS: Although knockdown of either S6K1 or GLI1 reduces the cellular proliferation of neuroblastoma cells, there is little effect of S6K1 on the expression of GLI1 mRNA and protein and on the capacity of GLI1 to activate target genes. No detectable phosphorylation of GLI1 is observed prior or following S6K1 knockdown. GLI1 overexpression can not rescue the reduced proliferation elicited by S6K1 knockdown. Moreover, inhibitors of PI3K/mTOR and GLI signaling reduced neuroblastoma cell growth, but no additional growth inhibitory effects were detected when the two classes of drugs were combined. CONCLUSION: Our results demonstrate that the impact of S6K1 kinase on neuroblastoma cells is not mediated through modulation of GLI1 expression/activity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2407-14-600) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-4152578 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-41525782014-09-04 The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling Diao, Yumei Rahman, Mohammed Ferdous-Ur Villegas, Victoria E Wickström, Malin Johnsen, John I Zaphiropoulos, Peter G BMC Cancer Research Article BACKGROUND: The crosstalk between Hedgehog (HH) signaling and other signal transduction cascades has been extensively studied in different cancers. In neuroblastoma, mTOR/S6K1 signaling is known to have a role in the development of this disease and recent evidence also implicates the HH pathway. Moreover, S6K1 kinase has been shown to phosphorylate GLI1, the effector of HH signaling, promoting GLI1 transcriptional activity and oncogenic function in esophageal adenocarcinoma. In this study, we examined the possible interplay of S6K1 and GLI1 signaling in neuroblastoma. METHODS: siRNA knockdowns were used to suppress S6K1 and GLI1 expression, and the siRNA effects were validated by real-time PCR and Western blotting. Cell proliferation analysis was performed with the EdU incorporation assay. Cytotoxic analysis with increasing concentrations of PI3K/mTOR and GLI inhibitors, individually and in combination, was used to determine drug response. RESULTS: Although knockdown of either S6K1 or GLI1 reduces the cellular proliferation of neuroblastoma cells, there is little effect of S6K1 on the expression of GLI1 mRNA and protein and on the capacity of GLI1 to activate target genes. No detectable phosphorylation of GLI1 is observed prior or following S6K1 knockdown. GLI1 overexpression can not rescue the reduced proliferation elicited by S6K1 knockdown. Moreover, inhibitors of PI3K/mTOR and GLI signaling reduced neuroblastoma cell growth, but no additional growth inhibitory effects were detected when the two classes of drugs were combined. CONCLUSION: Our results demonstrate that the impact of S6K1 kinase on neuroblastoma cells is not mediated through modulation of GLI1 expression/activity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2407-14-600) contains supplementary material, which is available to authorized users. BioMed Central 2014-08-18 /pmc/articles/PMC4152578/ /pubmed/25134527 http://dx.doi.org/10.1186/1471-2407-14-600 Text en © Diao et al.; licensee BioMed Central Ltd. 2014 This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Article Diao, Yumei Rahman, Mohammed Ferdous-Ur Villegas, Victoria E Wickström, Malin Johnsen, John I Zaphiropoulos, Peter G The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title | The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title_full | The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title_fullStr | The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title_full_unstemmed | The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title_short | The impact of S6K1 kinase on neuroblastoma cell proliferation is independent of GLI1 signaling |
title_sort | impact of s6k1 kinase on neuroblastoma cell proliferation is independent of gli1 signaling |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4152578/ https://www.ncbi.nlm.nih.gov/pubmed/25134527 http://dx.doi.org/10.1186/1471-2407-14-600 |
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