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Three dimensional reconstruction of the mouse cerebellum in Hedgehog-driven medulloblastoma models to identify Norrin-dependent effects on preneoplasia. Commun Biol 2022; 5:569. [PMID: 35680976 PMCID: PMC9184598 DOI: 10.1038/s42003-022-03507-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/19/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractSpontaneous mouse models of medulloblastoma (MB) offer a tractable system to study malignant progression in the brain. Mouse Sonic Hedgehog (Shh)-MB tumours first appear at postnatal stages as preneoplastic changes on the surface of the cerebellum, the external granule layer (EGL). Here we compared traditional histology and 3DISCO tissue clearing in combination with light sheet fluorescence microscopy (LSFM) to identify and quantify preneoplastic changes induced by disrupting stromal Norrin/Frizzled 4 (Fzd4) signalling, a potent tumour inhibitory signal in two mouse models of spontaneous Shh-MB. We show that 3DISCO-LSFM is as accurate as traditional histology for detecting Norrin/Fzd4-associated changes in PNL formation in Ptch+/− mice and EGL hyperplasia in Neurod2-SmoA1+/− mice. Moreover, we show that the anti-tumour effect of Norrin/Fzd4 signalling is restricted to the posterior region of the cerebellum and is characterized by defective neural progenitor migration away from the EGL. In conclusion, 3DISCO-LSFM is a valid way to monitor tumour initiation events in mouse MB models and reveals an unanticipated regional restriction of stromal signalling in constraining tumour initiation.
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2
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CSF1R inhibition depletes tumor-associated macrophages and attenuates tumor progression in a mouse sonic Hedgehog-Medulloblastoma model. Oncogene 2021; 40:396-407. [PMID: 33159168 PMCID: PMC7855734 DOI: 10.1038/s41388-020-01536-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 10/14/2020] [Accepted: 10/21/2020] [Indexed: 12/31/2022]
Abstract
The immune microenvironment of tumors can play a critical role in promoting or inhibiting tumor progression depending on the context. We present evidence that tumor-associated macrophages/microglia (TAMs) can promote tumor progression in the sonic hedgehog subgroup of medulloblastoma (SHH-MB). By combining longitudinal manganese-enhanced magnetic resonance imaging (MEMRI) and immune profiling of a sporadic mouse model of SHH-MB, we found the density of TAMs is higher in the ~50% of tumors that progress to lethal disease. Furthermore, reducing regulatory T cells or eliminating B and T cells in Rag1 mutants does not alter SHH-MB tumor progression. As TAMs are a dominant immune component in tumors and are normally dependent on colony-stimulating factor 1 receptor (CSF1R), we treated mice with a CSF1R inhibitor, PLX5622. Significantly, PLX5622 reduces a subset of TAMs, prolongs mouse survival, and reduces the volume of most tumors within 4 weeks of treatment. Moreover, concomitant with a reduction in TAMs the percentage of infiltrating cytotoxic T cells is increased, indicating a change in the tumor environment. Our studies in an immunocompetent preclinical mouse model demonstrate TAMs can have a functional role in promoting SHH-MB progression. Thus, CSF1R inhibition could have therapeutic potential for a subset of SHH-MB patients.
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3
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Tanno B, Babini G, Leonardi S, Giardullo P, De Stefano I, Pasquali E, Ottolenghi A, Atkinson MJ, Saran A, Mancuso M. Ex vivo miRNome analysis in Ptch1+/- cerebellum granule cells reveals a subset of miRNAs involved in radiation-induced medulloblastoma. Oncotarget 2018; 7:68253-68269. [PMID: 27626168 PMCID: PMC5356552 DOI: 10.18632/oncotarget.11938] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/05/2016] [Indexed: 12/15/2022] Open
Abstract
It has historically been accepted that incorrectly repaired DNA double strand breaks (DSBs) are the principal lesions of importance regarding mutagenesis, and long-term biological effects associated with ionizing radiation. However, radiation may also cause dysregulation of epigenetic processes that can lead to altered gene function and malignant transformation, and epigenetic alterations are important causes of miRNAs dysregulation in cancer. Patched1 heterozygous (Ptch1+/−) mice, characterized by aberrant activation of the Sonic hedgehog (Shh) signaling pathway, are a well-known murine model of spontaneous and radiation-induced medulloblastoma (MB), a common pediatric brain tumor originating from neural granule cell progenitors (GCPs). The high sensitivity of neonatal Ptch1+/− mice to radiogenic MB is dependent on deregulation of the Ptch1 gene function. Ptch1 activates a growth and differentiation programme that is a strong candidate for regulation through the non-coding genome. Therefore we carried out miRNA next generation sequencing in ex vivo irradiated and control GCPs, isolated and purified from cerebella of neonatal WT and Ptch1+/− mice. We identified a subset of miRNAs, namely let-7 family and miR-17∼92 cluster members, whose expression is altered in GCPs by radiation alone, or by synergistic interaction of radiation with Shh-deregulation. The same miRNAs were further validated in spontaneous and radiation-induced MBs from Ptch1+/− mice, confirming persistent deregulation of these miRNAs in the pathogenesis of MB. Our results support the hypothesis that miRNAs dysregulation is associated with radiosensitivity of GCPs and their neoplastic transformation in vivo.
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Affiliation(s)
- Barbara Tanno
- Laboratory of Biomedical Technologies, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Rome, Italy
| | | | - Simona Leonardi
- Laboratory of Biomedical Technologies, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Rome, Italy
| | - Paola Giardullo
- Department of Radiation Physics, Guglielmo Marconi University, Rome, Italy.,Department of Sciences, Roma Tre University, Rome, Italy
| | - Ilaria De Stefano
- Department of Radiation Physics, Guglielmo Marconi University, Rome, Italy
| | - Emanuela Pasquali
- Laboratory of Biomedical Technologies, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Rome, Italy
| | | | - Michael J Atkinson
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Biology, Neuherberg, Germany
| | - Anna Saran
- Laboratory of Biomedical Technologies, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Rome, Italy
| | - Mariateresa Mancuso
- Laboratory of Biomedical Technologies, Agenzia Nazionale per le Nuove Tecnologie, l'Energia e lo Sviluppo Economico Sostenibile (ENEA), Rome, Italy
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4
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Ryan KE, Kim PS, Fleming JT, Brignola E, Cheng FY, Litingtung Y, Chiang C. Lkb1 regulates granule cell migration and cortical folding of the cerebellar cortex. Dev Biol 2017; 432:165-177. [PMID: 28974424 PMCID: PMC5694378 DOI: 10.1016/j.ydbio.2017.09.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/28/2017] [Accepted: 09/28/2017] [Indexed: 12/17/2022]
Abstract
Cerebellar growth and foliation require the Hedgehog-driven proliferation of granule cell precursors (GCPs) in the external granule layer (EGL). However, that increased or extended GCP proliferation generally does not elicit ectopic folds suggests that additional determinants control cortical expansion and foliation during cerebellar development. Here, we find that genetic loss of the serine-threonine kinase Liver Kinase B1 (Lkb1) in GCPs increased cerebellar cortical size and foliation independent of changes in proliferation or Hedgehog signaling. This finding is unexpected given that Lkb1 has previously shown to be critical for Hedgehog pathway activation in cultured cells. Consistent with unchanged proliferation rate of GCPs, the cortical expansion of Lkb1 mutants is accompanied by thinning of the EGL. The plane of cell division, which has been implicated in diverse processes from epithelial surface expansions to gyrification of the human cortex, remains unchanged in the mutants when compared to wild-type controls. However, we find that Lkb1 mutants display delayed radial migration of post-mitotic GCPs that coincides with increased cortical size, suggesting that aberrant cell migration may contribute to the cortical expansion and increase foliation. Taken together, our results reveal an important role for Lkb1 in regulating cerebellar cortical size and foliation in a Hedgehog-independent manner.
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Affiliation(s)
- Kaitlyn E Ryan
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Patrick S Kim
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Jonathan T Fleming
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Emily Brignola
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Frances Y Cheng
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Ying Litingtung
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA
| | - Chin Chiang
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 4114 MRB III, Nashville, TN 37232, USA.
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5
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Bassett EA, Tokarew N, Allemano EA, Mazerolle C, Morin K, Mears AJ, McNeill B, Ringuette R, Campbell C, Smiley S, Pokrajac NT, Dubuc AM, Ramaswamy V, Northcott PA, Remke M, Monnier PP, Potter D, Paes K, Kirkpatrick LL, Coker KJ, Rice DS, Perez-Iratxeta C, Taylor MD, Wallace VA. Norrin/Frizzled4 signalling in the preneoplastic niche blocks medulloblastoma initiation. eLife 2016; 5. [PMID: 27823583 PMCID: PMC5100999 DOI: 10.7554/elife.16764] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 10/07/2016] [Indexed: 12/25/2022] Open
Abstract
The tumor microenvironment is a critical modulator of carcinogenesis; however, in many tumor types, the influence of the stroma during preneoplastic stages is unknown. Here we explored the relationship between pre-tumor cells and their surrounding stroma in malignant progression of the cerebellar tumor medulloblastoma (MB). We show that activation of the vascular regulatory signalling axis mediated by Norrin (an atypical Wnt)/Frizzled4 (Fzd4) inhibits MB initiation in the Ptch+/− mouse model. Loss of Norrin/Fzd4-mediated signalling in endothelial cells, either genetically or by short-term blockade, increases the frequency of pre-tumor lesions and creates a tumor-permissive microenvironment at the earliest, preneoplastic stages of MB. This pro-tumor stroma, characterized by angiogenic remodelling, is associated with an accelerated transition from preneoplasia to malignancy. These data expose a stromal component that regulates the earliest stages of tumorigenesis in the cerebellum, and a novel role for the Norrin/Fzd4 axis as an endogenous anti-tumor signal in the preneoplastic niche. DOI:http://dx.doi.org/10.7554/eLife.16764.001
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Affiliation(s)
- Erin A Bassett
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Nicholas Tokarew
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Ema A Allemano
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Chantal Mazerolle
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Katy Morin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Alan J Mears
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Brian McNeill
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Randy Ringuette
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
| | - Charles Campbell
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
| | - Sheila Smiley
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Neno T Pokrajac
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada
| | - Adrian M Dubuc
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Developmental and Stem Cell Biology Program, Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto, Canada
| | - Vijay Ramaswamy
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Developmental and Stem Cell Biology Program, Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada.,Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Canada
| | - Paul A Northcott
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Developmental and Stem Cell Biology Program, Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto, Canada
| | - Marc Remke
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Developmental and Stem Cell Biology Program, Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto, Canada
| | - Philippe P Monnier
- Genetics and Development Division, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - David Potter
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, United States
| | - Kim Paes
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, United States
| | - Laura L Kirkpatrick
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, United States
| | - Kenneth J Coker
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, United States
| | - Dennis S Rice
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, United States
| | - Carol Perez-Iratxeta
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
| | - Michael D Taylor
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.,Developmental and Stem Cell Biology Program, Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Canada
| | - Valerie A Wallace
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
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6
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Been RA, Ross JA, Nagel CW, Hooten AJ, Langer EK, DeCoursin KJ, Marek CA, Janik CL, Linden MA, Reed RC, Schutten MM, Largaespada DA, Johnson KJ. Perigestational dietary folic acid deficiency protects against medulloblastoma formation in a mouse model of nevoid basal cell carcinoma syndrome. Nutr Cancer 2014; 65:857-65. [PMID: 23909730 DOI: 10.1080/01635581.2013.804940] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Hereditary nevoid basal cell carcinoma syndrome (NBCCS) is caused by PTCH1 gene mutations that result in diverse neoplasms including medulloblastoma (MB). Epidemiological studies report reduced pediatric brain tumor risks associated with maternal intake of prenatal vitamins containing folic acid (FA) and FA supplements specifically. We hypothesized that low maternal FA intake during the perigestational period would increase MB incidence in a transgenic NBCCS mouse model, which carries an autosomal dominant mutation in the Ptch1 gene. Female wild-type C57BL/6 mice (n = 126) were randomized to 1 of 3 diets with differing FA amounts: 0.3 mg/kg (low), 2.0 mg/kg (control), and 8.0 mg/kg (high) 1 mo prior to mating with Ptch1 (+/-) C57BL/6 males. Females were maintained on the diet until pup weaning; the pups were then aged for tumor development. Compared to the control group, offspring MB incidence was significantly lower in the low FA group (Hazard Ratio = 0.47; 95% confidence interval 0.27-0.80) at 1 yr. No significant difference in incidence was observed between the control and high FA groups. Low maternal perigestational FA levels may decrease MB incidence in mice genetically predisposed to tumor development. Our results could have implications for prenatal FA intake recommendations in the presence of cancer syndromes.
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Affiliation(s)
- Raha A Been
- Masonic Cancer Center and Brain Tumor Program, University of Minnesota, Minneapolis, Minnesota 55455, USA
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7
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A population of Nestin-expressing progenitors in the cerebellum exhibits increased tumorigenicity. Nat Neurosci 2013; 16:1737-44. [PMID: 24141309 PMCID: PMC3845444 DOI: 10.1038/nn.3553] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 09/13/2013] [Indexed: 12/12/2022]
Abstract
It is generally believed that cerebellar granule neurons originate exclusively from granule neuron precursors (GNPs) in the external germinal layer (EGL). Here we identify a rare population of neuronal progenitors in mouse developing cerebellum that expresses Nestin. Although Nestin is widely considered a marker for multipotent stem cells, these Nestin-expressing progenitors (NEPs) are committed to the granule neuron lineage. Unlike conventional GNPs, which reside in the outer EGL and proliferate extensively, NEPs reside in the deep part of the EGL and are quiescent. Expression profiling reveals that NEPs are distinct from GNPs, and in particular, express markedly reduced levels of genes associated with DNA repair. Consistent with this, upon aberrant activation of Sonic hedgehog (Shh) signaling, NEPs exhibit more severe genomic instability and give rise to tumors more efficiently than GNPs. These studies identify a novel progenitor for cerebellar granule neurons and a novel cell of origin for medulloblastoma.
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8
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Fu J, Rodova M, Nanta R, Meeker D, Van Veldhuizen PJ, Srivastava RK, Shankar S. NPV-LDE-225 (Erismodegib) inhibits epithelial mesenchymal transition and self-renewal of glioblastoma initiating cells by regulating miR-21, miR-128, and miR-200. Neuro Oncol 2013; 15:691-706. [PMID: 23482671 DOI: 10.1093/neuonc/not011] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Glioblastoma multiforme is the most common form of primary brain tumor, often characterized by poor survival. Glioblastoma initiating cells (GICs) regulate self-renewal, differentiation, and tumor initiation properties and are involved in tumor growth, recurrence, and resistance to conventional treatments. The sonic hedgehog (SHH) signaling pathway is essential for normal development and embryonic morphogenesis. The objectives of this study were to examine the molecular mechanisms by which GIC characteristics are regulated by NPV-LDE-225 (Smoothened inhibitor; (2,2'-[[dihydro-2-(4-pyridinyl)-1,3(2H,4H)-pyrimidinediyl]bis(methylene)]bis[N,N-dimethylbenzenamine). METHODS Cell viability and apoptosis were measured by XTT and annexin V-propidium iodide assay, respectively. Gli translocation and transcriptional activities were measured by immunofluorescence and luciferase assay, respectively. Gene and protein expressions were measured by quantitative real-time PCR and Western blot analyses, respectively. RESULTS AND CONCLUSION NPV-LDE-225 inhibited cell viability, neurosphere formation, and Gli transcriptional activity and induced apoptosis by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase. NPV-LDE-225 increased the expression of tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-R1/DR4, TRAIL-R2/DR5, and Fas and decreased the expression of platelet derived growth factor receptor-α and Bcl2, and these effects were abrogated by Gli1 plus Gli2 short hairpin RNAs. NPV-LDE-225 enhanced the therapeutic potential of FasL and TRAIL by upregulating Fas and DR4/5, respectively. Interestingly, NPV-LDE-225 induced expression of programmed cell death 4 and apoptosis and inhibited cell viability by suppressing micro RNA (miR)-21. Furthermore, NPV-LDE-225 inhibited pluripotency-maintaining factors Nanog, Oct4, Sox2, and cMyc. The inhibition of Bmi1 by NPV-LDE-225 was regulated by induction of miR-128. Finally, NPV-LDE-225 suppressed epithelial-mesenchymal transition by upregulating E-cadherin and inhibiting N-cadherin, Snail, Slug, and Zeb1 through modulating the miR-200 family. Our data highlight the importance of the SHH pathway for self-renewal and early metastasis of GICs.
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Affiliation(s)
- Junsheng Fu
- Department of Pathology and Laboratory Medicine, The University of Kansas Cancer Center, The University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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9
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Oncogenic YAP promotes radioresistance and genomic instability in medulloblastoma through IGF2-mediated Akt activation. Oncogene 2011; 31:1923-37. [PMID: 21874045 PMCID: PMC3583298 DOI: 10.1038/onc.2011.379] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Radiation therapy remains the standard of care for many cancers, including the malignant pediatric brain tumor medulloblastoma. Radiation leads to long-term side effects, while radio-resistance contributes to tumor recurrence. Radio-resistant medulloblastoma cells occupy the peri-vascular niche. They express Yes-associated protein (YAP), a Sonic hedgehog (Shh) target markedly elevated in Shh-driven medulloblastomas. Here we report that YAP accelerates tumor growth and confers radio-resistance, promoting ongoing proliferation after radiation. YAP activity enables cells to enter mitosis with un-repaired DNA through driving IGF2 expression and Akt activation, resulting in ATM/Chk2 inactivation and abrogation of cell cycle checkpoints. Our results establish a central role for YAP in counteracting radiation-based therapies and driving genomic instability, and indicate the YAP/IGF2/Akt axis as a therapeutic target in medulloblastoma.
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10
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Abstract
Cerebral cortical progenitor cells can be classified into several different types, and each progenitor type integrates cell-intrinsic and cell-extrinsic cues to regulate neurogenesis. On one hand, cell-intrinsic mechanisms that depend upon appropriate apical-basal polarity are established by adherens junctions and apical complex proteins and are particularly important in progenitors with apical processes contacting the lateral ventricle. The apical protein complexes themselves are concentrated at the ventricular surface, and apical complex proteins regulate mitotic spindle orientation and cell fate. On the other hand, remarkably little is known about how cell-extrinsic cues signal to progenitors and couple with cell-intrinsic mechanisms to instruct neurogenesis. Recent research shows that the cerebrospinal fluid, which contacts apical progenitors at the ventricular surface and bathes the apical complex of these cells, provides growth- and survival-promoting cues for neural progenitor cells in developing and adult brain. This review addresses how the apical-basal polarity of progenitor cells regulates cell fate and allows progenitors to sample diffusible signals distributed by the cerebrospinal fluid. We also review several classes of signaling factors that the cerebrospinal fluid distributes to the developing brain to instruct neurogenesis.
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Affiliation(s)
- Maria K Lehtinen
- Division of Genetics, Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA.
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11
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Abstract
In the last 20 years, it has become clear that developmental genes and their regulators, noncoding RNAs including microRNAs and long-noncoding RNAs, within signaling pathways play a critical role in the pathogenesis of cancer. Many of these pathways were first identified in genetic screens in Drosophila and other lower organisms. Mammalian orthologs were subsequently identified and genes within the pathways cloned and found to regulate cell growth. Genes and pathways expressed during embryonic development, including the Notch, Wnt/β-Catenin, TGF-β/BMP, Shh/Patched, and Hippo pathways are mutated, lost, or aberrantly regulated in a wide variety of human cancers, including skin, breast, blood, and brain cancers, including medulloblastoma. These biochemical pathways affect cell fate determination, axis formation, and patterning during development and regulate tissue homeostasis and regeneration in adults. Medulloblastoma, the most common malignant nervous system tumor in childhood, are thought to arise from disruptions in cerebellar development [reviewed by Marino, S. (2005)]. Defining the extracellular cues and intracellular signaling pathways that control cerebellar neurogenesis, especially granule cell progenitor (GCP) proliferation and differentiation has been useful for developing models to unravel the mechanisms underlying medulloblastoma formation and growth. In this chapter, we will review the development of the cerebellar cortex, highlighting signaling pathways of potential relevance to tumorigenesis.
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Affiliation(s)
- Martine F Roussel
- Department of Tumor Cell Biology and Genetics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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12
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Ohshima-Hosoyama S, Hosoyama T, Nelon LD, Keller C. IGF-1 receptor inhibition by picropodophyllin in medulloblastoma. Biochem Biophys Res Commun 2010; 399:727-32. [PMID: 20692232 DOI: 10.1016/j.bbrc.2010.08.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 08/03/2010] [Indexed: 11/16/2022]
Abstract
The insulin-like growth factor-1 receptor (Igf1r) is a multifunctional membrane-associated tyrosine kinase associated with regulation of transformation, proliferation, differentiation and apoptosis. Increased IGF pathway activity has been reported in human and murine medulloblastoma. Tumors from our genetically-engineered medulloblastoma mouse model over-express Igf1r, and thus this mouse model is a good platform with which to study the role of Igf1r in tumor progression. We hypothesize that inhibition of IGF pathway in medulloblastoma can slow or inhibit tumor growth and metastasis. To test our hypothesis, we tested the role of IGF in tumor growth in vitro by treatment with the tyrosine kinase small molecule inhibitor, picropodophyllin (PPP), which strongly inhibits the IGF pathway. Our results demonstrate that PPP-mediated downregulation of the IGF pathway inhibits mouse tumor cell growth and induces apoptotic cell death in vitro in primary medulloblastoma cultures that are most reflective of tumor cell behavior in vivo.
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Affiliation(s)
- Sachiko Ohshima-Hosoyama
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center, San Antonio, TX 78229, USA
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