1
|
Shahab SW, Roggeveen CM, Sun J, Kunhiraman H, McSwain LF, Juraschka K, Kumar SA, Saulnier O, Taylor MD, Schniederjan M, Schnepp RW, MacDonald TJ, Kenney AM. The LIN28B-let-7-PBK pathway is essential for group 3 medulloblastoma tumor growth and survival. Mol Oncol 2023; 17:1784-1802. [PMID: 37341142 PMCID: PMC10483609 DOI: 10.1002/1878-0261.13477] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/28/2023] [Accepted: 06/19/2023] [Indexed: 06/22/2023] Open
Abstract
Children with Group 3 medulloblastoma (G3 MB) have a very poor prognosis, and many do not survive beyond 5 years after diagnosis. A factor that may contribute to this is the lack of available targeted therapy. Expression of protein lin-28 homolog B (LIN28B), a regulator of developmental timing, is upregulated in several cancers, including G3 MB, and is associated with worse survival in this disease. Here, we investigate the role of the LIN28B pathway in G3 MB and demonstrate that the LIN28B-lethal-7 (let-7; a microRNA that is a tumor suppressor)-lymphokine-activated killer T-cell-originated protein kinase (PBK; also known as PDZ-binding kinase) axis promotes G3 MB proliferation. LIN28B knockdown in G3-MB-patient-derived cell lines leads to a significant reduction in cell viability and proliferation in vitro and in prolonged survival of mice with orthotopic tumors. The LIN28 inhibitor N-methyl-N-[3-(3-methyl-1,2,4-triazolo[4,3-b]pyridazin-6-yl)phenyl]acetamide (1632) significantly reduces G3 MB cell growth and demonstrates efficacy in reducing tumor growth in mouse xenograft models. Inhibiting PBK using HI-TOPK-032 also results in a significant reduction in G3 MB cell viability and proliferation. Together, these results highlight a critical role for the LIN28B-let-7-PBK pathway in G3 MB and provide preliminary preclinical results for drugs targeting this pathway.
Collapse
Affiliation(s)
- Shubin W. Shahab
- Aflac Cancer and Blood Disorders CenterChildren's Healthcare of AtlantaGAUSA
- Department of PediatricsEmory University School of MedicineAtlantaGAUSA
| | | | - Jiarong Sun
- Emory College of Arts and SciencesEmory UniversityAtlantaGAUSA
| | | | - Leon F. McSwain
- Department of PediatricsEmory University School of MedicineAtlantaGAUSA
| | - Kyle Juraschka
- Department of Neurosurgery, The Hospital for Sick ChildrenUniversity of TorontoONCanada
- Department of Laboratory Medicine and PathologyUniversity of TorontoONCanada
| | - Sachin A. Kumar
- Department of Laboratory Medicine and PathologyUniversity of TorontoONCanada
| | - Olivier Saulnier
- The Arthur and Sonia Labatt Brain Tumor Research Centre, The Hospital for Sick ChildrenUniversity of TorontoONCanada
- Developmental and Stem Cell Biology Program, The Hospital for Sick ChildrenUniversity of TorontoONCanada
| | - Michael D. Taylor
- Department of Neurosurgery, The Hospital for Sick ChildrenUniversity of TorontoONCanada
- Department of Laboratory Medicine and PathologyUniversity of TorontoONCanada
| | | | - Robert W. Schnepp
- Aflac Cancer and Blood Disorders CenterChildren's Healthcare of AtlantaGAUSA
- Department of PediatricsEmory University School of MedicineAtlantaGAUSA
- The Janssen PharmaceuticalAmblerPAUSA
| | - Tobey J MacDonald
- Aflac Cancer and Blood Disorders CenterChildren's Healthcare of AtlantaGAUSA
- Department of PediatricsEmory University School of MedicineAtlantaGAUSA
- Winship Cancer InstituteAtlantaGAUSA
| | - Anna Marie Kenney
- Department of PediatricsEmory University School of MedicineAtlantaGAUSA
- Winship Cancer InstituteAtlantaGAUSA
| |
Collapse
|
2
|
Kunhiraman H, McSwain L, Shahab SW, Gershon TR, MacDonald TJ, Kenney AM. IGFBP2 promotes proliferation and cell migration through STAT3 signaling in Sonic hedgehog medulloblastoma. Acta Neuropathol Commun 2023; 11:62. [PMID: 37029430 PMCID: PMC10082504 DOI: 10.1186/s40478-023-01557-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/25/2023] [Indexed: 04/09/2023] Open
Abstract
Medulloblastoma (MB) is the most common pediatric brain malignancy and is divided into four molecularly distinct subgroups: WNT, Sonic Hedgehog (SHHp53mut and SHHp53wt), Group 3, and Group 4. Previous reports suggest that SHH MB features a unique tumor microenvironment compared with other MB groups. To better understand how SHH MB tumor cells interact with and potentially modify their microenvironment, we performed cytokine array analysis of culture media from freshly isolated MB patient tumor cells, spontaneous SHH MB mouse tumor cells and mouse and human MB cell lines. We found that the SHH MB cells produced elevated levels of IGFBP2 compared to non-SHH MBs. We confirmed these results using ELISA, western blotting, and immunofluorescence staining. IGFBP2 is a pleiotropic member of the IGFBP super-family with secreted and intracellular functions that can modulate tumor cell proliferation, metastasis, and drug resistance, but has been understudied in medulloblastoma. We found that IGFBP2 is required for SHH MB cell proliferation, colony formation, and cell migration, through promoting STAT3 activation and upregulation of epithelial to mesenchymal transition markers; indeed, ectopic STAT3 expression fully compensated for IGFBP2 knockdown in wound healing assays. Taken together, our findings reveal novel roles for IGFBP2 in SHH medulloblastoma growth and metastasis, which is associated with very poor prognosis, and they indicate an IGFBP2-STAT3 axis that could represent a novel therapeutic target in medulloblastoma.
Collapse
Affiliation(s)
- Haritha Kunhiraman
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA
| | - Leon McSwain
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA
| | - Shubin W Shahab
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA
| | - Timothy R Gershon
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA
| | - Tobey J MacDonald
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA
| | - Anna Marie Kenney
- Department of Pediatrics, Neuro-Oncology Division and Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Emory University, 1760 Haygood Drive, Atlanta, GA, 30322, USA.
- Winship Cancer Institute, Emory University, Atlanta, GA, 30322, USA.
| |
Collapse
|
3
|
McSwain LF, Parwani KK, Shahab SW, Hambardzumyan D, MacDonald TJ, Spangle JM, Kenney AM. Medulloblastoma and the DNA Damage Response. Front Oncol 2022; 12:903830. [PMID: 35747808 PMCID: PMC9209741 DOI: 10.3389/fonc.2022.903830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/10/2022] [Indexed: 12/04/2022] Open
Abstract
Medulloblastoma (MB) is the most common malignant brain tumor in children with standard of care consisting of surgery, radiation, and chemotherapy. Recent molecular profiling led to the identification of four molecularly distinct MB subgroups – Wingless (WNT), Sonic Hedgehog (SHH), Group 3, and Group 4. Despite genomic MB characterization and subsequent tumor stratification, clinical treatment paradigms are still largely driven by histology, degree of surgical resection, and presence or absence of metastasis rather than molecular profile. Patients usually undergo resection of their tumor followed by craniospinal radiation (CSI) and a 6 month to one-year multi-agent chemotherapeutic regimen. While there is clearly a need for development of targeted agents specific to the molecular alterations of each patient, targeting proteins responsible for DNA damage repair could have a broader impact regardless of molecular subgrouping. DNA damage response (DDR) protein inhibitors have recently emerged as targeted agents with potent activity as monotherapy or in combination in different cancers. Here we discuss the molecular underpinnings of genomic instability in MB and potential avenues for exploitation through DNA damage response inhibition.
Collapse
Affiliation(s)
- Leon F. McSwain
- Department of Pediatrics, Emory University, Atlanta, GA, United States
| | - Kiran K. Parwani
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
- Department of Radiation Oncology, Emory University, Atlanta, GA, United States
| | - Shubin W. Shahab
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
| | - Dolores Hambardzumyan
- Departments of Neurosurgery and Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Tobey J. MacDonald
- Department of Pediatrics, Emory University, Atlanta, GA, United States
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
| | - Jennifer M. Spangle
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
- Department of Radiation Oncology, Emory University, Atlanta, GA, United States
| | - Anna Marie Kenney
- Department of Pediatrics, Emory University, Atlanta, GA, United States
- *Correspondence: Anna Marie Kenney,
| |
Collapse
|
4
|
Robinson MH, Maximov V, Lallani S, Farooq H, Taylor MD, Read RD, Kenney AM. Upregulation of the chromatin remodeler HELLS is mediated by YAP1 in Sonic Hedgehog Medulloblastoma. Sci Rep 2019; 9:13611. [PMID: 31541170 PMCID: PMC6754407 DOI: 10.1038/s41598-019-50088-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 08/22/2019] [Indexed: 12/29/2022] Open
Abstract
Medulloblastoma is a malignant pediatric tumor that arises from neural progenitors in the cerebellum. Despite a five-year survival rate of ~70%, nearly all patients incur adverse side effects from current treatment strategies that drastically impact quality of life. Roughly one-third of medulloblastoma are driven by aberrant activation of the Sonic Hedgehog (SHH) signaling pathway. However, the scarcity of genetic mutations in medulloblastoma has led to investigation of other mechanisms contributing to cancer pathogenicity including epigenetic regulation of gene expression. Here, we show that Helicase, Lymphoid Specific (HELLS), a chromatin remodeler with epigenetic functions including DNA methylation and histone modification, is induced by Sonic Hedgehog (SHH) in SHH-dependent cerebellar progenitor cells and the developing murine cerebella. HELLS is also up-regulated in mouse and human SHH medulloblastoma. Others have shown that HELLS activity generally results in a repressive chromatin state. Our results demonstrate that increased expression of HELLS in our experimental systems is regulated by the oncogenic transcriptional regulator YAP1 downstream of Smoothened, the positive transducer of SHH signaling. Elucidation of HELLS as one of the downstream effectors of the SHH pathway may lead to novel targets for precision therapeutics with the promise of better outcomes for SHH medulloblastoma patients.
Collapse
Affiliation(s)
- M Hope Robinson
- Department of Pediatric Oncology, Emory University, Atlanta, GA, 30322, USA
- Cancer Biology Graduate Program, Winship Cancer Institute, Emory University, Atlanta, GA, USA
| | - Victor Maximov
- Department of Pediatric Oncology, Emory University, Atlanta, GA, 30322, USA
| | - Shoeb Lallani
- Department of Pharmacology, Emory University, Atlanta, GA, 30322, USA
| | - Hamza Farooq
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Division of Neurosurgery, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Surgery, Department of Laboratory Medicine and Pathobiology, and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Michael D Taylor
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Division of Neurosurgery, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Surgery, Department of Laboratory Medicine and Pathobiology, and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Renee D Read
- Department of Pharmacology, Emory University, Atlanta, GA, 30322, USA
- Winship Cancer Institute, Atlanta, GA, 30322, USA
| | - Anna Marie Kenney
- Department of Pediatric Oncology, Emory University, Atlanta, GA, 30322, USA.
- Winship Cancer Institute, Atlanta, GA, 30322, USA.
| |
Collapse
|
5
|
Potts C, Robinson H, Eyrich N, Malhotra A, Dey A, Kenney AM. MEDU-35. Nox4 MEDIATED HIF1a STABILIZATION IN SONIC HEDGEHOG MEDULLOBLASTOMA TUMOR REPOPULATING CELLS. Neuro Oncol 2019. [DOI: 10.1093/neuonc/noz036.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
6
|
Wei Y, Maximov V, Morrissy SA, Taylor MD, Pallas DC, Kenney AM. p53 Function Is Compromised by Inhibitor 2 of Phosphatase 2A in Sonic Hedgehog Medulloblastoma. Mol Cancer Res 2018; 17:186-198. [PMID: 30224541 DOI: 10.1158/1541-7786.mcr-18-0485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/10/2018] [Accepted: 08/21/2018] [Indexed: 01/09/2023]
Abstract
Medulloblastomas, the most common malignant pediatric brain tumors, have been genetically defined into four subclasses, namely WNT-activated, Sonic Hedgehog (SHH)-activated, Group 3, and Group 4. Approximately 30% of medulloblastomas have aberrant SHH signaling and thus are referred to as SHH-activated medulloblastoma. The tumor suppressor gene TP53 has been recently recognized as a prognostic marker for patients with SHH-activated medulloblastoma; patients with mutant TP53 have a significantly worse outcome than those with wild-type TP53. It remains unknown whether p53 activity is impaired in SHH-activated, wild-type TP53 medulloblastoma, which is about 80% of the SHH-activated medulloblastomas. Utilizing the homozygous NeuroD2:SmoA1 mouse model with wild-type Trp53, which recapitulates human SHH-activated medulloblastoma, it was discovered that the endogenous Inhibitor 2 of Protein Phosphatase 2A (SET/I2PP2A) suppresses p53 function by promoting accumulation of phospho-MDM2 (S166), an active form of MDM2 that negatively regulates p53. Knockdown of I2PP2A in SmoA1 primary medulloblastoma cells reduced viability and proliferation in a p53-dependent manner, indicating the oncogenic role of I2PP2A. Importantly, this mechanism is conserved in the human medulloblastoma cell line ONS76 with wild-type TP53. Taken together, these findings indicate that p53 activity is inhibited by I2PP2A upstream of PP2A in SHH-activated and TP53-wildtype medulloblastomas. IMPLICATIONS: This study suggests that I2PP2A represents a novel therapeutic option and its targeting could improve the effectiveness of current therapeutic regimens for SHH-activated or other subclasses of medulloblastoma with wild-type TP53.
Collapse
Affiliation(s)
- Yun Wei
- Department of Pediatrics, Emory University, Atlanta, Georgia.,Winship Cancer Institute, Atlanta, Georgia
| | - Victor Maximov
- Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Sorana A Morrissy
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Michael D Taylor
- The Hospital for Sick Children (SickKids), University of Toronto, Toronto, Ontario, Canada
| | - David C Pallas
- Winship Cancer Institute, Atlanta, Georgia.,Department of Biochemistry, Emory University, Atlanta, Georgia
| | - Anna Marie Kenney
- Department of Pediatrics, Emory University, Atlanta, Georgia. .,Winship Cancer Institute, Atlanta, Georgia
| |
Collapse
|
7
|
Malhotra A, Dey A, Kenney AM. Abstract B12: Yes-Associated Protein: A master metabolic regulator In medulloblastoma. Mol Cancer Res 2016. [DOI: 10.1158/1557-3125.metca15-b12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Downstream of mitogenic Sonic hedgehog (Shh) signaling, Yes-Associated Protein (YAP) can drive proliferation in Cerebellar Granule Neural Progenitor (CGNP) cells. CGNPs are the proposed cells of origin of SHH medulloblastomas. They are a neural progenitor type whose developmental expansion requires signaling by Shh, a secreted ligand produced by the neighboring Purkinje neurons. Approximately 30% of human medulloblastomas bear an activated Sonic hedgehog pathway gene expression signature. Ectopic expression of YAP promotes highly aggressive Shh-driven medulloblastoma growth and radio-resistance (Fernandez et al., 2009). Medulloblastoma being the most common solid malignancy of childhood and a leading cause of pediatric mortality, the current standard of care results in about 60% “cure” rate. But the survivors are beset with long-term side effects, including cognitive impairment, seizures, premature aging, and susceptibility to cancer. Moreover, recurrence and metastasis are lethal. Therefore, identification of novel modes of molecular targeted therapies is critical for the improved quality of life for survivors and reduced incidence of recurrence and metastasis.
Recently, there has been renewed interest in how altered metabolic patterns in tumors could be exploited for therapeutic purposes. Deregulating the metabolic machinery for aberrant energy utilization is one of the hallmarks of a proliferating cancer cell. Previously, our lab made the novel observation that Shh mitogenic/oncogenic signaling is tightly coupled to the reprogramming of mitochondrial bioenergetics: Shh inhibits fatty acid oxidation (FAO, or β-oxidation) while driving increased fatty acid synthesis (FAS), an early step of lipogenesis. The production of citrate, an essential component for fatty acid synthesis, occurs inside the mitochondrion via the Tri-carboxylic acid cycle (TCA).
We analyzed the effect of Shh treatment and ectopic YAP expression on CGNPs and found that YAP increases levels of fatty acid synthase (FASN) and ATP citrate lyase (ACLY), while YAP knock-down in Shh-treated CGNPs resulted in reduced levels of these enzymes. Moreover, we also observed a surprising decrease in mitochondrial membrane potential. This prompted us to further analyze the ultrastructure of mitochondria using Transmission Electron Microscopy. Shh-treated or ectopic YAP-expressing mitochondria presented a swollen morphology, along with an expanded matrix space and deformed cristae structure, typical of morphologically aberrant mitochondria. These differences in mitochondrial structure were also visible in ultrastructures of SmoA1 tumor tissue as well as in vitro cultures of SmoA1 tumor cells (MBCs). Being dynamic structures, mitochondria undergo constant fusion and fission events, which contribute to their biogenesis. Expression of fusion genes Mitofusin 1 and 2 was reduced while DRP1, a fission promoting gene was highly induced in all samples under study. Ectopic expression of Mitofusin 1 and 2, and knock down of DRP1 in CGNPs and MBCs not only restores the membrane potential to the non-proliferating state, but also indicates a reduction in proliferation.
Our study thus implicates YAP-regulated metabolic pathways and enzymes as potential targets for novel medulloblastoma therapies. Our goal is to determine whether hampering YAP-mediated mitochondrial fragmentation can restore the metabolic profile of tumor cells to that of non-transformed, non-proliferating cells, thus suggesting a potential novel treatment paradigm that may reduce or eliminate the requirement for high dose radiation.
Citation Format: Anshu Malhotra, Abhinav Dey, Anna Marie Kenney. Yes-Associated Protein: A master metabolic regulator In medulloblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B12.
Collapse
|
8
|
Malhotra A, Dey A, Prasad N, Kenney AM. Sonic Hedgehog Signaling Drives Mitochondrial Fragmentation by Suppressing Mitofusins in Cerebellar Granule Neuron Precursors and Medulloblastoma. Mol Cancer Res 2015; 14:114-24. [PMID: 26446920 DOI: 10.1158/1541-7786.mcr-15-0278] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/28/2015] [Indexed: 12/22/2022]
Abstract
UNLABELLED Sonic hedgehog (Shh) signaling is closely coupled with bioenergetics of medulloblastoma, the most common malignant pediatric brain tumor. Shh-associated medulloblastoma arises from cerebellar granule neuron precursors (CGNP), a neural progenitor whose developmental expansion requires signaling by Shh, a ligand secreted by the neighboring Purkinje neurons. Previous observations show that Shh signaling inhibits fatty acid oxidation although driving increased fatty acid synthesis. Proliferating CGNPs and mouse Shh medulloblastomas feature high levels of glycolytic enzymes in vivo and in vitro. Because both of these metabolic processes are closely linked to mitochondrial bioenergetics, the role of Shh signaling in mitochondrial biogenesis was investigated. This report uncovers a surprising decrease in mitochondrial membrane potential (MMP) and overall ATP production in CGNPs exposed to Shh, consistent with increased glycolysis resulting in high intracellular acidity, leading to mitochondrial fragmentation. Ultrastructural examination of mitochondria revealed a spherical shape in Shh-treated cells, in contrast to the elongated appearance in vehicle-treated postmitotic cells. Expression of mitofusin 1 and 2 was reduced in these cells, although their ectopic expression restored the MMP to the nonproliferating state and the morphology to a fused, interconnected state. Mouse Shh medulloblastoma cells featured drastically impaired mitochondrial morphology, restoration of which by ectopic mitofusin expression was also associated with a decrease in the expression of Cyclin D2 protein, a marker for proliferation. IMPLICATIONS This report exposes a novel role for Shh in regulating mitochondrial dynamics and rescue of the metabolic profile of tumor cells to that of nontransformed, nonproliferating cells and represents a potential avenue for development of medulloblastoma therapeutics.
Collapse
Affiliation(s)
- Anshu Malhotra
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Abhinav Dey
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Niyathi Prasad
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Anna Marie Kenney
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia. Winship Cancer Institute, Atlanta, Georgia.
| |
Collapse
|
9
|
Lee HY, Angelastro JM, Kenney AM, Mason CA, Greene LA. Reciprocal actions of ATF5 and Shh in proliferation of cerebellar granule neuron progenitor cells. Dev Neurobiol 2012; 72:789-804. [PMID: 22095825 DOI: 10.1002/dneu.20979] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Precise regulation of neuroprogenitor cell proliferation and differentiation is required for successful brain development, but the factors that contribute to this are only incompletely understood. The transcription factor ATF5 promotes proliferation of cerebral cortical neuroprogenitor cells and its down regulation permits their differentiation. Here, we examine the expression and regulation of ATF5 in cerebellar granule neuron progenitor cells (CGNPs) as well as the role of ATF5 in the transition of CGNPs to postmitotic cerebellar granule neurons (GCNs). We find that ATF5 is expressed by proliferating CGNPs in both the embryonic and postnatal cerebellar external granule layer (EGL) and in the rhombic lip, the embryonic structure from which the EGL arises. In contrast, ATF5 is undetectable in postmitotic GCNs. In highly enriched dissociated cultures of CGNPs and CGNs, ATF5 is expressed only in CGNPs. Constitutive ATF5 expression in CGNPs does not affect their proliferation or exit from the cell cycle. In contrast, in presence of sonic hedgehog (Shh), a mitogen for CGNPs, constitutively expressed ATF5 promotes CGNP proliferation and delays their cell cycle exit and differentiation. Conversely, ATF5 loss-of-function conferred by a dominant-negative form of ATF5 significantly diminishes Shh-stimulated CGNP proliferation and promotes differentiation. In parallel with its stimulation of CGNP proliferation, Shh enhances ATF5 expression by what appeared to be a posttranscriptional mechanism involving protein stabilization. These findings indicate a reciprocal interaction between ATF5 and Shh in which Shh stimulates ATF5 expression and in which ATF5 contributes to Shh-stimulated CGNP expansion.
Collapse
Affiliation(s)
- Hae Young Lee
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | | | | | | | | |
Collapse
|
10
|
Affiliation(s)
- Lori A Mainwaring
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | | | | |
Collapse
|
11
|
Mainwaring LA, Kenney AM. Divergent functions for eIF4E and S6 kinase by sonic hedgehog mitogenic signaling in the developing cerebellum. Oncogene 2011; 30:1784-97. [PMID: 21339731 DOI: 10.1038/onc.2010.564] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cerebellar development entails rapid peri-natal proliferation of cerebellar granule neuron precursors (CGNPs), proposed cells-of-origin for certain medulloblastomas. CGNPs require insulin-like growth factor (IGF) for survival and sonic hedgehog (Shh)-implicated in medulloblastoma-for proliferation. The IGF-responsive kinase mammalian target of rapamycin (mTOR) drives proliferation-associated protein synthesis. We asked whether Shh signaling regulates mTOR targets to promote CGNP proliferation despite constitutive IGF signaling under proliferative and differentiation-promoting conditions. Surprisingly, Shh promoted eukaryotic initiation factor 4E (eIF4E) expression, but inhibited S6 kinase (S6K). In vivo, S6K activity specifically marked the CGNP population transitioning from proliferation-competent to post-mitotic. Indeed, eIF4E was required for CGNP proliferation, while S6K activation drove cell cycle exit. Protein phosphatase 2A (PP2A) inhibition rescued S6K activity. Moreover, Shh upregulated the PP2A B56γ subunit, which targets S6K for inactivation and was required for CGNP proliferation. These findings reveal unique developmental functions for eIF4E and S6 kinase wherein their activity is specifically uncoupled by mitogenic Shh signaling.
Collapse
Affiliation(s)
- L A Mainwaring
- Biochemistry, Cell, and Molecular Biology Program, Weill Medical College of Cornell University, New York, NY, USA
| | | |
Collapse
|
12
|
Bhatia B, Malik A, Fernandez-L A, Kenney AM. p27(Kip1), a double-edged sword in Shh-mediated medulloblastoma: Tumor accelerator and suppressor. Cell Cycle 2010; 9:4307-14. [PMID: 21051932 DOI: 10.4161/cc.9.21.13441] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Medulloblastoma, a brain tumor arising in the cerebellum, is the most common solid childhood malignancy. the current standard of care for medulloblastoma leaves survivors with life-long side effects. Gaining insight into mechanisms regulating transformation of medulloblastoma cells-of-origin may lead to development of better treatments for these tumors. Cerebellar granule neuron precursors (CGNps) are proposed cells-of-origin for certain classes of medulloblastoma, specifically those marked by aberrant Sonic hedgehog (Shh) signaling pathway activation. CGNps require signaling by Shh for proliferation during brain development. In mitogen-stimulated cells, nuclear localized cyclin dependent kinase (cdk) inhibitor p27 (Kip1) functions as a checkpoint control at the G1- to S-phase transition by inhibiting cdk2. Recent studies have suggested cytoplasmically localized p27(Kip1) acquires oncogenic functions. Here, we show that p27(Kip1) is cytoplasmically localized in CGNps and mouse Shh-mediated medulloblastomas. transgenic mice bearing an activating mutation in the Shh pathway and lacking one or both p27(Kip1) alleles have accelerated tumor incidence compared to mice bearing both p27(Kip1) alleles. Interestingly, mice heterozygous for p27(Kip1) have decreased survival latency compared to p27(Kip1)-null animals. our data indicate that this may reflect the requirement for at least one copy of p27(Kip1) for recruiting cyclin D/cdk4/6 to promote cell cycle progression yet insufficient expression in the heterozygous or null state to inhibit cyclin E/cdk2. Finally, we find that mis-localized p27(Kip1) may play a positive role in motility in medulloblastoma cells. Together, our data indicate that the dosage of p27(Kip1) plays a role in cell cycle progression and tumor suppression in Shh-mediated medulloblastoma expansion.
Collapse
Affiliation(s)
- Bobby Bhatia
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | | | | | | |
Collapse
|
13
|
Parathath SR, Mainwaring LA, Fernandez-L A, Guldal CG, Nahlé Z, Kenney AM. β-Arrestin-1 links mitogenic sonic hedgehog signaling to the cell cycle exit machinery in neural precursors. Cell Cycle 2010; 9:4013-24. [PMID: 20935513 DOI: 10.4161/cc.9.19.13325] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Development of the cerebellum, a brain region regulating posture and coordination, occurs post-natally and is marked by rapid proliferation of granule neuron precursors (CGNPs), stimulated by mitogenic Sonic hedgehog (Shh) signaling. β-Arrestin (βArr) proteins play important roles downstream of Smoothened, the Shh signal transducer. However, whether Shh regulates βArrs and what role they play in Shh-driven CGNP proliferation remains to be determined. Here, we report that Shh induces βArr1 accumulation and localization to the nucleus, where it participates in enhancing expression of the cyclin dependent kinase (cdk) inhibitor p27, whose accumulation eventually drives CGNP cell cycle exit. βArr1 knockdown enhances CGNP proliferation and reduces p27 expression. Thus, Shh-mediated βArr1 induction represents a novel negative feedback loop within the Shh mitogenic pathway, such that ongoing Shh signaling, while required for CGNPs to proliferate, also sets up a cell-intrinsic clock programming their ultimate exit from the cell cycle.
Collapse
Affiliation(s)
- Susana R Parathath
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | | | | | | | | | | |
Collapse
|
14
|
Mainwaring LA, Bhatia B, Kenney AM. Myc on my mind: a transcription factor family's essential role in brain development. Oncotarget 2010; 1:86-88. [PMID: 21297222 PMCID: PMC3157705 DOI: 10.18632/oncotarget.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 06/10/2010] [Indexed: 11/25/2022] Open
|
15
|
Abstract
Certain types of medulloblastoma, the most common solid pediatric cancer, are proposed to arise from neural precursors known as cerebellar granule neuron precursors (CGNPs), which require signaling by Sonic hedgehog (Shh) and insulin-like growth factor (IGF) for their proliferation and survival. Aberrant activity of these pathways is implicated in medulloblastoma. IGF activates the mammalian Target of Rapamycin (mTOR), a growth-promoting kinase normally kept in check by the tumor suppressive Tuberous Sclerosis Complex (TSC), comprised of TSC1 and TSC2. TSC also counteracts proliferation by stabilizing the cyclin-dependent kinase inhibitor p27(Kip1), preventing progression through G(1)- to S-phase of the cell cycle. We reported that mice with impaired TSC activity show increased susceptibility to Shh-mediated medulloblastoma. CGNPs and tumors from these mice display increased proliferation, mTOR pathway activation, glycogen synthase kinase-3 (GSK-3) alpha/beta inactivation, and atypical p27(Kip1) cytoplasmic localization. GSK-3alpha/beta inactivation was mTOR-dependent, whereas p27(Kip1) localization was uncoupled from mTOR, and was instead regulated by TSC2. These results provide insight into the molecular 'hardwiring' of the mitogenic network downstream of Shh signaling and emphasize the separate yet synergistic effects regulated by the TSC complex in (1) fueling proliferation through mTOR activation/GSK-3alpha/beta inactivation and (2) compromising checkpoint mechanisms via TSC2-dependent p27(Kip1) nuclear exclusion. Future medulloblastoma therapies targeting Shh signaling can be developed to selectively modulate these activities, to restore checkpoint control and attenuate uncontrolled hyperproliferation.
Collapse
Affiliation(s)
- Bobby Bhatia
- Department of Cancer Biology and Genetics and Brain Tumor Center, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | | | | |
Collapse
|
16
|
Fernandez-L A, Northcott PA, Dalton J, Fraga C, Ellison D, Angers S, Taylor MD, Kenney AM. YAP1 is amplified and up-regulated in hedgehog-associated medulloblastomas and mediates Sonic hedgehog-driven neural precursor proliferation. Genes Dev 2009; 23:2729-41. [PMID: 19952108 DOI: 10.1101/gad.1824509] [Citation(s) in RCA: 301] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Medulloblastoma is the most common solid malignancy of childhood, with treatment side effects reducing survivors' quality of life and lethality being associated with tumor recurrence. Activation of the Sonic hedgehog (Shh) signaling pathway is implicated in human medulloblastomas. Cerebellar granule neuron precursors (CGNPs) depend on signaling by the morphogen Shh for expansion during development, and have been suggested as a cell of origin for certain medulloblastomas. Mechanisms contributing to Shh pathway-mediated proliferation and transformation remain poorly understood. We investigated interactions between Shh signaling and the recently described tumor-suppressive Hippo pathway in the developing brain and medulloblastomas. We report up-regulation of the oncogenic transcriptional coactivator yes-associated protein 1 (YAP1), which is negatively regulated by the Hippo pathway, in human medulloblastomas with aberrant Shh signaling. Consistent with conserved mechanisms between brain tumorigenesis and development, Shh induces YAP1 expression in CGNPs. Shh also promotes YAP1 nuclear localization in CGNPs, and YAP1 can drive CGNP proliferation. Furthermore, YAP1 is found in cells of the perivascular niche, where proposed tumor-repopulating cells reside. Post-irradiation, YAP1 was found in newly growing tumor cells. These findings implicate YAP1 as a new Shh effector that may be targeted by medulloblastoma therapies aimed at eliminating medulloblastoma recurrence.
Collapse
Affiliation(s)
- Africa Fernandez-L
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
MicroRNAS (miRNAs) are small endogenous non-coding RNAs that play important roles in many different biological processes including proliferation, differentiation and apoptosis through silencing of target genes. Emerging evidence indicates that miRNAs are key players in mammalian development that, when altered, contribute to tumorigenesis. However, only a few studies to date have focused on the role of miRNAs in medulloblastoma, the most common malignant pediatric brain tumor. These tumors arise in the cerebellum and may attribute their origins to deregulated proliferation of neural progenitor cells during development. Understanding the interplay between normal brain development and medulloblastoma pathogenesis is necessary in order for more efficient, less toxic targeted therapies to be developed and implemented. MiRNA expression profiling of both mouse and human medulloblastomas has led to the identification of signatures correlating with the molecular subgroups of medulloblastoma, tumor diagnosis and response to treatment, as well as novel targets of potential clinical relevance. This review summarizes the recent miRNA literature in both medulloblastoma and normal brain development.
Collapse
Affiliation(s)
- Africa Fernandez-L
- Department of Cancer Biology and Genetics and Brain Tumor Center, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | | | | | | |
Collapse
|
18
|
Bhatia B, Northcott PA, Hambardzumyan D, Govindarajan B, Brat DJ, Arbiser JL, Holland EC, Taylor MD, Kenney AM. Tuberous sclerosis complex suppression in cerebellar development and medulloblastoma: separate regulation of mammalian target of rapamycin activity and p27 Kip1 localization. Cancer Res 2009; 69:7224-34. [PMID: 19738049 DOI: 10.1158/0008-5472.can-09-1299] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
During development, proliferation of cerebellar granule neuron precursors (CGNP), candidate cells-of-origin for the pediatric brain tumor medulloblastoma, requires signaling by Sonic hedgehog (Shh) and insulin-like growth factor (IGF), the pathways of which are also implicated in medulloblastoma. One of the consequences of IGF signaling is inactivation of the mammalian target of rapamycin (mTOR)-suppressing tuberous sclerosis complex (TSC), comprised of TSC1 and TSC2, leading to increased mRNA translation. We show that mice, in which TSC function is impaired, display increased mTOR pathway activation, enhanced CGNP proliferation, glycogen synthase kinase-3 alpha/beta (GSK-3 alpha/beta) inactivation, and cytoplasmic localization of the cyclin-dependent kinase inhibitor p27(Kip1), which has been proposed to cause its inactivation or gain of oncogenic functions. We observed the same characteristics in wild-type primary cultures of CGNPs in which TSC1 and/or TSC2 were knocked down, and in mouse medulloblastomas induced by ectopic Shh pathway activation. Moreover, Shh-induced mouse medulloblastomas manifested Akt-mediated TSC2 inactivation, and the mutant TSC2 allele synergized with aberrant Shh signaling to increase medulloblastoma incidence in mice. Driving exogenous TSC2 expression in Shh-induced medulloblastoma cells corrected p27(Kip1) localization and reduced proliferation. GSK-3 alpha/beta inactivation in the tumors in vivo and in primary CGNP cultures was mTOR-dependent, whereas p27(Kip1) cytoplasmic localization was regulated upstream of mTOR by TSC2. These results indicate that a balance between Shh mitogenic signaling and TSC function regulating new protein synthesis and cyclin-dependent kinase inhibition is essential for the normal development and prevention of tumor formation or expansion.
Collapse
Affiliation(s)
- Bobby Bhatia
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Northcott PA, Fernandez-L A, Hagan JP, Ellison DW, Grajkowska W, Gillespie Y, Grundy R, Van Meter T, Rutka JT, Croce CM, Kenney AM, Taylor MD. The miR-17/92 polycistron is up-regulated in sonic hedgehog-driven medulloblastomas and induced by N-myc in sonic hedgehog-treated cerebellar neural precursors. Cancer Res 2009; 69:3249-55. [PMID: 19351822 DOI: 10.1158/0008-5472.can-08-4710] [Citation(s) in RCA: 243] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Medulloblastoma is the most common malignant pediatric brain tumor, and mechanisms underlying its development are poorly understood. We identified recurrent amplification of the miR-17/92 polycistron proto-oncogene in 6% of pediatric medulloblastomas by high-resolution single-nucleotide polymorphism genotyping arrays and subsequent interphase fluorescence in situ hybridization on a human medulloblastoma tissue microarray. Profiling the expression of 427 mature microRNAs (miRNA) in a series of 90 primary human medulloblastomas revealed that components of the miR-17/92 polycistron are the most highly up-regulated miRNAs in medulloblastoma. Expression of miR-17/92 was highest in the subgroup of medulloblastomas associated with activation of the sonic hedgehog (Shh) signaling pathway compared with other subgroups of medulloblastoma. Medulloblastomas in which miR-17/92 was up-regulated also had elevated levels of MYC/MYCN expression. Consistent with its regulation by Shh, we observed that Shh treatment of primary cerebellar granule neuron precursors (CGNP), proposed cells of origin for the Shh-associated medulloblastomas, resulted in increased miR-17/92 expression. In CGNPs, the Shh effector N-myc, but not Gli1, induced miR-17/92 expression. Ectopic miR-17/92 expression in CGNPs synergized with exogenous Shh to increase proliferation and also enabled them to proliferate in the absence of Shh. We conclude that miR-17/92 is a positive effector of Shh-mediated proliferation and that aberrant expression/amplification of this miR confers a growth advantage to medulloblastomas.
Collapse
Affiliation(s)
- Paul A Northcott
- Division of Neurosurgery, Arthur and Sonia Labatt Brain Tumour Research Centre, Program in Developmental and Stem Cell Biology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Otto T, Horn S, Brockmann M, Eilers U, Schüttrumpf L, Popov N, Kenney AM, Schulte JH, Beijersbergen R, Christiansen H, Berwanger B, Eilers M. Stabilization of N-Myc is a critical function of Aurora A in human neuroblastoma. Cancer Cell 2009; 15:67-78. [PMID: 19111882 DOI: 10.1016/j.ccr.2008.12.005] [Citation(s) in RCA: 403] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 11/25/2008] [Accepted: 12/08/2008] [Indexed: 12/11/2022]
Abstract
In human neuroblastoma, amplification of the MYCN gene predicts poor prognosis and resistance to therapy. In a shRNA screen of genes that are highly expressed in MYCN-amplified tumors, we have identified AURKA as a gene that is required for the growth of MYCN-amplified neuroblastoma cells but largely dispensable for cells lacking amplified MYCN. Aurora A has a critical function in regulating turnover of the N-Myc protein. Degradation of N-Myc requires sequential phosphorylation by cyclin B/Cdk1 and Gsk3. N-Myc is therefore degraded during mitosis in response to low levels of PI3-kinase activity. Aurora A interacts with both N-Myc and the SCF(Fbxw7) ubiquitin ligase that ubiquitinates N-Myc and counteracts degradation of N-Myc, thereby uncoupling N-Myc stability from growth factor-dependent signals.
Collapse
Affiliation(s)
- Tobias Otto
- Institute of Molecular Biology and Tumor Research, Marburg, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Parathath SR, Mainwaring LA, Fernandez-L A, Campbell DO, Kenney AM. Insulin receptor substrate 1 is an effector of sonic hedgehog mitogenic signaling in cerebellar neural precursors. Development 2008; 135:3291-300. [PMID: 18755774 DOI: 10.1242/dev.022871] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Sonic hedgehog (SHH) and insulin-like growth factor (IGF) signaling are essential for development of many tissues and are implicated in medulloblastoma, the most common solid pediatric malignancy. Cerebellar granule neuron precursors (CGNPs), proposed cells-of-origin for specific classes of medulloblastomas, require SHH and IGF signaling for proliferation and survival during development of the cerebellum. We asked whether SHH regulates IGF pathway components in proliferating CGNPs. We report that SHH-treated CGNPs showed increased levels of insulin receptor substrate 1 (IRS1) protein, which was also present in the germinal layer of the developing mouse cerebellum and in mouse SHH-induced medulloblastomas. Previous roles for IRS1, an oncogenic protein that is essential for IGF-mediated proliferation in other cell types, have not been described in SHH-mediated CGNP proliferation. We found that IRS1 overexpression can maintain CGNP proliferation in the absence of SHH. Furthermore, lentivirus-mediated knock down experiments have shown that IRS1 activity is required for CGNP proliferation in slice explants and dissociated cultures. Contrary to traditional models for SHH signaling that focus on gene transcription, SHH stimulation does not regulate Irs1 transcription but rather stabilizes IRS1 protein by interfering with mTOR-dependent IRS1 turnover and possibly affects Irs1 mRNA translation. Thus, we have identified IRS1 as a novel effector of SHH mitogenic signaling that may serve as a future target for medulloblastoma therapies. Our findings also indicate a previously unreported interaction between the SHH and mTOR pathways, and provide an example of a non-classical means for SHH-mediated protein regulation during development.
Collapse
Affiliation(s)
- Susana R Parathath
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | | | | | | | | |
Collapse
|
22
|
Hatton BA, Knoepfler PS, Kenney AM, Rowitch DH, de Alborán IM, Olson JM, Eisenman RN. N-myc is an essential downstream effector of Shh signaling during both normal and neoplastic cerebellar growth. Cancer Res 2007; 66:8655-61. [PMID: 16951180 DOI: 10.1158/0008-5472.can-06-1621] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We examined the genetic requirements for the Myc family of oncogenes in normal Sonic hedgehog (Shh)-mediated cerebellar granule neuronal precursor (GNP) expansion and in Shh pathway-induced medulloblastoma formation. In GNP-enriched cultures derived from N-myc(Fl/Fl) and c-myc(Fl/Fl) mice, disruption of N-myc, but not c-myc, inhibited the proliferative response to Shh. Conditional deletion of c-myc revealed that, although it is necessary for the general regulation of brain growth, it is less important for cerebellar development and GNP expansion than N-myc. In vivo analysis of compound mutants carrying the conditional N-myc null and the activated Smoothened (ND2:SmoA1) alleles showed, that although granule cells expressing the ND2:SmoA1 transgene are present in the N-myc null cerebellum, no hyperproliferation or tumor formation was detected. Taken together, these findings provide in vivo evidence that N-myc acts downstream of Shh/Smo signaling during GNP proliferation and that N-myc is required for medulloblastoma genesis even in the presence of constitutively active signaling from the Shh pathway.
Collapse
Affiliation(s)
- Beryl A Hatton
- Clinical Research Division, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA 98109, USA.
| | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
Signaling by the sonic hedgehog (Shh) pathway is essential for neural precursor population expansion during normal central nervous system (CNS) development, and is implicated in the childhood brain tumor, medulloblastoma. The proto-oncogene N-myc plays essential roles as a downstream effector of Shh proliferative effects in neural precursors of the cerebellum, where medulloblastomas arise. It is likely that N-Myc has analogous functions in medulloblastomas and other CNS tumors where it is highly expressed due to altered regulation or gene amplification. Myc destabilization occurs in response to phosphorylation by GSK-3beta. N-Myc degradation is required for cerebellar neural precursors to exit the cell cycle. During mitosis in cerebellar neural precursors, levels of N-Myc primed for phosphorylation by GSK-3beta increase, due to cdk1 complex activity towards N-Myc. GSK-3beta is kept in check by insulin-like growth factor signaling, which also plays critical roles in brain development and cancer. These findings indicate that therapeutic strategies targeting N-myc and the IGF pathway might be effective against medulloblastoma.
Collapse
Affiliation(s)
- Paul S Knoepfler
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | | |
Collapse
|
24
|
Sjostrom SK, Finn G, Hahn WC, Rowitch DH, Kenney AM. The Cdk1 Complex Plays a Prime Role in Regulating N-Myc Phosphorylation and Turnover in Neural Precursors. Dev Cell 2005; 9:327-38. [PMID: 16139224 DOI: 10.1016/j.devcel.2005.07.014] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 04/23/2005] [Accepted: 07/28/2005] [Indexed: 12/23/2022]
Abstract
Myc family transcription factors are destabilized by phosphorylation of a conserved amino-terminal GSK-3beta motif. In proliferating cerebellar granule neuron precursors (CGNPs), Sonic hedgehog signaling induces N-myc expression, and N-myc protein is stabilized by insulin-like growth factor-mediated suppression of GSK-3beta. N-myc phosphorylation-mediated degradation is a prerequisite for CGNP growth arrest and differentiation. We investigated whether N-myc phosphorylation and turnover are thus linked to cell cycle exit in primary mouse CGNP cultures and the developing cerebellum. We report that phosphorylation-induced turnover of endogenous N-myc protein in CGNPs increases during mitosis, due to increased priming phosphorylation of N-myc for GSK-3beta. The priming phosphorylation requires the Cdk1 complex, whose cyclin subunits are indirect Sonic hedgehog targets. These findings provide a mechanism for promoting growth arrest in the final cycle of neural precursor proliferation competency, or for resetting the cell cycle in the G1 phase, by destabilizing N-myc in mitosis.
Collapse
Affiliation(s)
- Sarah K Sjostrom
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | | | |
Collapse
|
25
|
|
26
|
Kenney AM, Widlund HR, Rowitch DH. Hedgehog and PI-3 kinase signaling converge on Nmyc1 to promote cell cycle progression in cerebellar neuronal precursors. Development 2003; 131:217-28. [PMID: 14660435 DOI: 10.1242/dev.00891] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Neuronal precursor cells in the developing cerebellum require activity of the sonic hedgehog (Shh) and phosphoinositide-3-kinase (PI3K) pathways for growth and survival. Synergy between the Shh and PI3K signaling pathways are implicated in the cerebellar tumor medulloblastoma. Here, we describe a mechanism through which these disparate signaling pathways cooperate to promote proliferation of cerebellar granule neuron precursors. Shh signaling drives expression of mRNA encoding the Nmyc1 oncoprotein (previously N-myc), which is essential for expansion of cerebellar granule neuron precursors. The PI3K pathway stabilizes Nmyc1 protein via inhibition of GSK3-dependent Nmyc1 phosphorylation and degradation. The effects of PI3K activity on Nmyc1 stabilization are mimicked by insulin-like growth factor, a PI3K agonist with roles in central nervous system precursor growth and tumorigenesis. These findings indicate that Shh and PI3K signaling pathways converge on N-Myc to regulate neuronal precursor cell cycle progression. Furthermore, they provide a rationale for therapeutic targeting of PI3K signaling in medulloblastoma.
Collapse
Affiliation(s)
- Anna Marie Kenney
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | | | | |
Collapse
|
27
|
Kenney AM, Cole MD, Rowitch DH. Nmyc upregulation by sonic hedgehog signaling promotes proliferation in developing cerebellar granule neuron precursors. Development 2003; 130:15-28. [PMID: 12441288 DOI: 10.1242/dev.00182] [Citation(s) in RCA: 385] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Hedgehog pathway activation is required for expansion of specific neuronal precursor populations during development and is etiologic in the human cerebellar tumor, medulloblastoma. We report that sonic hedgehog (Shh) signaling upregulates expression of the proto-oncogene Nmyc in cultured cerebellar granule neuron precursors (CGNPs) in the absence of new protein synthesis. The temporal-spatial expression pattern of Nmyc, but not other Myc family members, precisely coincides with regions of hedgehog proliferative activity in the developing cerebellum and is observed in medulloblastomas of Patched (Ptch) heterozygous mice. Overexpression of Nmyc promotes cell-autonomous G(1) cyclin upregulation and CGNP proliferation independent of Shh signaling. Furthermore, Myc antagonism in vitro significantly decreases proliferative effects of Shh in cultured CGNPs. Together, these findings identify Nmyc as a direct target of the Shh pathway that functions to regulate cell cycle progression in cerebellar granule neuron precursors.
Collapse
Affiliation(s)
- Anna Marie Kenney
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | | | | |
Collapse
|
28
|
Zhao Q, Kho A, Kenney AM, Yuk Di DI, Kohane I, Rowitch DH. Identification of genes expressed with temporal-spatial restriction to developing cerebellar neuron precursors by a functional genomic approach. Proc Natl Acad Sci U S A 2002; 99:5704-9. [PMID: 11960025 PMCID: PMC122835 DOI: 10.1073/pnas.082092399] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hedgehog pathway activation is required for proliferation of cerebellar granule cell neuron precursors during development and is etiologic in certain cerebellar tumors. To identify genes expressed specifically in granule cell neuron precursors, we used oligonucleotide microarrays to analyze regulation of 13,179 genes/expressed sequence tags in heterogeneous primary cultures of neonatal mouse cerebellum that respond to the mitogen Sonic hedgehog. In conjunction, we applied experiment-specific noise models to render a gene-by-gene robust indication of up-regulation in Sonic hedgehog-treated cultures. Twelve genes so identified were tested, and 10 (83%) showed appropriate expression in the external granular layer (EGL) of the postnatal day (PN) 7 cerebellum and down-regulation by PN 15, as verified by in situ hybridization. Whole-organ profiling of the developing cerebellum was carried out from PN 1 to 30 to generate a database of temporal gene regulation profiles (TRPs). From the database an algorithm was developed to capture the TRP typical of EGL-specific genes. The "TRP-EGL" accurately predicted expression in vivo of an additional 18 genes/expressed sequence tags with a sensitivity of 80% and a specificity of 88%. We then compared the positive predictive value of our analytical procedure with other widely used methods, as verified by the TRP-EGL in silico. These findings suggest that replicate experiments and incorporation of noise models increase analytical specificity. They further show that genome-wide methods are an effective means to identify stage-specific gene expression in the developing granule cell lineage.
Collapse
Affiliation(s)
- Qing Zhao
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
| | | | | | | | | | | |
Collapse
|
29
|
Abstract
Sonic hedgehog (Shh) signal transduction via the G-protein-coupled receptor, Smoothened, is required for proliferation of cerebellar granule neuron precursors (CGNPs) during development. Activating mutations in the Hedgehog pathway are also implicated in basal cell carcinoma and medulloblastoma, a tumor of the cerebellum in humans. However, Shh signaling interactions with cell cycle regulatory components in neural precursors are poorly understood, in part because appropriate immortalized cell lines are not available. We have utilized primary cultures from neonatal mouse cerebella in order to determine (i) whether Shh initiates or maintains cell cycle progression in CGNPs, (ii) if G(1) regulation by Shh resembles that of classical mitogens, and (iii) whether individual D-type cyclins are essential components of Shh proliferative signaling in CGNPs. Our results indicate that Shh can drive continued cycling in immature, proliferating CGNPs. Shh treatment resulted in sustained activity of the G(1) cyclin-Rb axis by regulating levels of cyclinD1, cyclinD2, and cyclinE mRNA transcripts and proteins. Analysis of CGNPs from cyclinD1(-/-) or cyclinD2(-/-) mice demonstrates that the Shh proliferative pathway does not require unique functions of cyclinD1 or cyclinD2 and that D-type cyclins overlap functionally in this regard. In contrast to many known mitogenic pathways, we show that Shh proliferative signaling is mitogen-activated protein kinase independent. Furthermore, protein synthesis is required for early effects on cyclin gene expression. Together, our results suggest that Shh proliferative signaling promotes synthesis of regulatory factor intermediates that upregulate or maintain cyclin gene expression and activity of the G(1) cyclin-Rb axis in proliferating granule neuron precursors.
Collapse
Affiliation(s)
- A M Kenney
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA
| | | |
Collapse
|
30
|
Dib-Hajj SD, Black JA, Cummins TR, Kenney AM, Kocsis JD, Waxman SG. Rescue of alpha-SNS sodium channel expression in small dorsal root ganglion neurons after axotomy by nerve growth factor in vivo. J Neurophysiol 1998; 79:2668-76. [PMID: 9582237 DOI: 10.1152/jn.1998.79.5.2668] [Citation(s) in RCA: 149] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Small (18-25 microm diam) dorsal root ganglion (DRG) neurons are known to express high levels of tetrodotoxin-resistant (TTX-R) sodium current and the mRNA for the alpha-SNS sodium channel, which encodes a TTX-R channel when expressed in oocytes. These neurons also preferentially express the high affinity receptor for nerve growth factor (NGF), TrkA. Levels of TTX-R sodium current and of alpha-SNS mRNA are reduced in these cells after axotomy. To determine whether NGF participates in the regulation of TTX-R current and alpha-SNS mRNA in small DRG neurons in vivo, we axotomized small lumbar DRG neurons by sciatic nerve transection and administered NGF or Ringer solution to the proximal nerve stump using osmotic pumps. Ten to 12 days after pump implant, whole cell patch-clamp recording demonstrated that TTX-R current density was decreased in Ringer-treated axotomized neurons (154 +/- 45 pA/pF; mean +/- SE) compared with nonaxotomized control neurons (865 +/- 123 pA/pF) and was restored partially toward control levels in NGF-treated axotomized neurons (465 +/- 78 pA/pF). The V1/2 for steady-state activation and inactivation of TTX-R currents were similar in control, Ringer- and NGF-treated axotomized neurons. Reverse transcription polymerase chain reaction revealed an upregulation of alpha-SNS mRNA levels in NGF-treated compared with Ringer-treated axotomized DRG. In situ hybridization showed that alpha-SNS mRNA levels were decreased significantly in small Ringer-treated axotomized DRG neurons in vivo and also in small DRG neurons that were dissociated and maintained in vitro, so as to correspond to the patch-clamp conditions. NGF-treated axotomized neurons had a significant increase in alpha-SNS mRNA expression, compared with Ringer-treated axotomized cells. These results show that the administration of exogenous NGF in vivo, to the proximal nerve stump of the transected sciatic nerve, results in an upregulation of TTX-R sodium current and of alpha-SNS mRNA levels in small DRG neurons. Retrogradely transported NGF thus appears to participate in the control of excitability in these cells via actions that include the regulation of sodium channel gene expression in vivo.
Collapse
Affiliation(s)
- S D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | | | | | | | | | | |
Collapse
|
31
|
Kenney AM, Kocsis JD. Peripheral axotomy induces long-term c-Jun amino-terminal kinase-1 activation and activator protein-1 binding activity by c-Jun and junD in adult rat dorsal root ganglia In vivo. J Neurosci 1998; 18:1318-28. [PMID: 9454841 PMCID: PMC2605350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
One of the earliest documented molecular events after sciatic nerve injury in adult rats is the rapid, long-term upregulation of the immediate early gene transcription factor c-Jun mRNA and protein in lumbar dorsal root ganglion (DRG) neurons, suggesting that c-Jun may regulate genes that are important both in the early post-injury period and during later peripheral axonal regeneration. However, neither the mechanism through which c-Jun protein is increased nor the level of its post-injury transcriptional activity in axotomized DRGs has been characterized. To determine whether transcriptional activation of c-Jun occurs in response to nerve injury in vivo and is associated with axonal regeneration, we have assayed axotomized adult rat DRGs for evidence of jun kinase activation, c-Jun phosphorylation, and activator protein-1 (AP-1) binding. We report that sciatic nerve transection resulted in chronic activation of c-Jun amino-terminal kinase-1 (JNK) in L4/L5 DRGs concomitant with c-Jun amino-terminal phosphorylation in neurons, and lasting AP-1 binding activity, with both c-Jun and JunD participating in DNA binding complexes. The timing of JNK activation was dependent on the distance of the axotomy site from the DRGs, suggesting the requirement for a retrograde transport-mediated signal. AP-1 binding and c-Jun protein returned to basal levels in DRGs as peripheral regeneration was completed but remained elevated in the case of chronic sprouting, indicating that c-Jun may regulate target genes that are involved in axonal outgrowth.
Collapse
Affiliation(s)
- A M Kenney
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | | |
Collapse
|
32
|
Nazareno MI, Eleserio G, Kenney AM, Collado E. Into reproductive health. Integration 1998:30-3. [PMID: 12294076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
|
33
|
Kenney AM, Kocsis JD. Temporal variability of jun family transcription factor levels in peripherally or centrally transected adult rat dorsal root ganglia. Brain Res Mol Brain Res 1997; 52:53-61. [PMID: 9450677 DOI: 10.1016/s0169-328x(97)00211-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Enhanced chemiluminescent (ECL) immunoblotting was used to quantitatively assess the initial changes in jun family transcription factor protein levels in adult rat lumbar dorsal root ganglia (DRG) after peripheral axotomy and dorsal root transection, and to study the effects of neurotrophic factor administration on these changes. Transection of central (dorsal root) or peripheral (spinal nerve) branches of DRG neurons resulted in rapid elevation of c-jun protein levels, which was transient after dorsal root transection but sustained, though slightly attenuated, after spinal nerve transection. These results suggest that injury-induced c-jun elevation is biphasic, consisting of an early, transient, injury-initiated phase and a more prolonged secondary phase specific to peripheral target disconnection. c-jun protein changes were not modulated by administration of NGF or BDNF. Immunohistochemistry was used to localize c-jun protein induction to DRG neurons. Using ECL immunoblotting, we also observed temporally regulated increases in junD protein levels after both injuries. A transient up-regulation of junB was detected by immunoblotting 5 days after peripheral axotomy, coincident with a slight decrease in c-jun protein levels.
Collapse
Affiliation(s)
- A M Kenney
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
| | | |
Collapse
|
34
|
Abstract
In situ hybridization and immunohistochemical studies have shown that sciatic nerve crush or transection induces upregulation of the immediate early gene c-jun mRNA and protein in lumbar dorsal root ganglion neurons. Here we have used enhanced chemiluminescent (ECL) immunoblotting as a sensitive and quantitative way of measuring the time of course of c-jun protein induction following sciatic nerve transection at two distances from the L4 and L5 dorsal root ganglia. c-Jun protein was first detected within 3 h of proximal sciatic nerve transection and within 6 h of distal nerve transection. These results indicate substantially earlier increases in c-jun protein after nerve injury than previously reported, which can be attributed to the sensitivity of this detection method. The earlier induction of c-jun after proximal as compared to distal nerve transection supports the hypothesis that the c-jun response to sciatic nerve injury involves a distance-dependent signalling mechanism.
Collapse
Affiliation(s)
- A M Kenney
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
| | | |
Collapse
|
35
|
Affiliation(s)
- K L Lankford
- Department of Neurology, Yale University School of Medicine and Neuroscience, West Haven, CT, USA
| | | | | |
Collapse
|
36
|
Torres A, Kenney AM. Expanding Medicaid coverage for pregnant women: estimates of the impact and cost. Fam Plann Perspect 1989; 21:19-24. [PMID: 2649392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An estimated 361,000 pregnant women are expected to be newly eligible for Medicaid coverage when all states raise the income ceiling for such coverage to 100 percent of the federal poverty level by 1990, as Congress has mandated. According to a methodology for projecting the effects of recent congressional changes in the Medicaid program, about 64 percent of these women would be otherwise uninsured, at least for maternity care, and the rest would have some insurance, so Medicaid would be the payer of last resort. Congress has also given states the option to cover pregnant women with incomes from 100 to 185 percent of poverty. If all states were to do so, another 552,000 women would become eligible, 29 percent of whom would otherwise have no insurance coverage for maternity care. The estimate of newly eligible women with incomes below 185 percent of poverty represents 24 percent of the 3.8 million women who give birth in the United States each year. Under the 100-percent-of-poverty ceiling, the estimated number of poor women eligible for coverage ranges from 4,000 or fewer in 18 states and the District of Columbia to 41,000 in California and Texas. At 185 percent of poverty, the number ranges from 4,000 or fewer in 11 states and the District of Columbia to more than 90,000 in California and Texas. Eight states have already elected to extend Medicaid coverage to the 185-percent-of-poverty ceiling.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
|
37
|
Gold RB, Kenney AM, Singh S. Paying for maternity care in the United States. Fam Plann Perspect 1987; 19:190-206. [PMID: 3319681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
38
|
Kenney AM, Torres A, Dittes N, Macias J. Medicaid expenditures for maternity and newborn care in America. Fam Plann Perspect 1986; 18:103-10. [PMID: 3100323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An Alan Guttmacher Institute (AGI) survey of the Medicaid programs in each state and the District of Columbia found that some 542,000 low-income women have a Medicaid-subsidized delivery each year--about 15 percent of all women who give birth. The proportion ranges from three percent in Alaska to 25 percent in Michigan. The federal and state governments spend almost $1.2 billion annually for maternity care (including prenatal, postpartum and newborn care); the average expenditure per patient is $2,200. Tennessee reports the highest expenditure per patient ($3,500) and Louisiana the lowest ($1,300). Only the highest payments under Medicaid are close to charges for maternity care in the open market, a fact that results in a significant disincentive for physicians and hospitals to accept Medicaid patients. The $1.2 billion spent for Medicaid-subsidized maternity care compares with an estimated $11.5 billion spent for such care nationwide. Thus, Medicaid pays for about 10 percent of the nation's maternity care bill, although Medicaid subsidizes deliveries for 15 percent of all women who give birth. The figures for maternity care do not include Medicaid expenditures for neonatal intensive care, which, for the 17 states reporting data, average about $11,800 per infant. Although only about six percent of all newborns whose deliveries are subsidized by Medicaid require neonatal intensive care, such care is so expensive that it adds about 30 percent to all Medicaid expenditures for maternity care. Increased Medicaid payments for maternity care, including prenatal care, could have a positive impact on health outcomes for low-income mothers and their babies, and could reduce the necessity for massive and expensive medical treatment for newborns.
Collapse
|
39
|
Kenney AM. School-based clinics: a national conference. Fam Plann Perspect 1986; 18:44-6. [PMID: 3803548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
40
|
Rosoff JI, Kenney AM. Title X and its critics. Fam Plann Perspect 1984; 16:111-6, 119. [PMID: 6468640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
41
|
Kenney AM, Orr MT. Sex education: an overview of current programs, policies, and research. Phi Delta Kappan 1984; 65:491-496. [PMID: 12339949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
42
|
Kenney AM, Forrest JD, Torres A. Storm over Washington: the parental notification proposal. Fam Plann Perspect 1982; 14:185, 187-90, 192-7. [PMID: 7117507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
43
|
Kenney AM, Hartung TG, Dewsbury DA. Copulatory behavior and the initiation of pregnancy in California voles (Microtus californicus). Brain Behav Evol 1979; 16:176-91. [PMID: 385105 DOI: 10.1159/000121835] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The copulatory behavior of Microtus californicus and its effect on pregnancy initiation were examined in two experiments. In experiment 1 18 males and 18 females which had received exogenous hormones participated in 54 tests of copulatory behavior, each continued to a satiety criterion of 30 min with no copulations. The basic pattern involved no lock, intravaginal thrusting, ejaculation possible on a single insertion and multiple ejaculation. Ejaculation frequency ranged from 1 to 5, with a mean of 2.2. In experiment 2, it was found that all females receiving satiety tests of copulatory behavior while in male-induced estrus ovulated and became pregnant. Whereas all 10 females receiving one ejaculation ovulated, only 60% became pregnant. Thus, it appears that copulation beyond one ejaculation functions in increasing the likelihood of pregnancy. By comparing different species of Microtus it is proposed that copulatory patterns in which males persist for many thrusts and ejaculations may have evolved in conjunction with ornate penile morphology, large litter sizes, and high stimulus requirements for the initiation of ovulation and a funtional luteal phase.
Collapse
|
44
|
Kenney AM, Hartung TG, Davis HN, Gray GD, Zerylnick M, Dewsbury DA. Male copulatory behavior and the induction of ovulation in female voles: a quest for species specificity. Horm Behav 1978; 11:123-30. [PMID: 372083 DOI: 10.1016/0018-506x(78)90063-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
45
|
Anderson CO, Kenney AM, Mason WA. Effects of maternal mobility, partner, and endocrine state on social responsiveness of adolescent rhesus monkeys. Dev Psychobiol 1977; 10:421-34. [PMID: 410688 DOI: 10.1002/dev.420100503] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The social behavior of rhesus monkeys raised for the 1st year of life with mobile (MS) or stationary (SS) cloth surrogate mothers was investigated when the animals reached 4-5 yr of age. The MS males generally refrained from social interaction during initial pairings with females, whereas SS males interacted frequently, but were more often the targets of attacks and chases from adult females than were MS males. The MS males were more likely to vary their social behavior according to the behavior of the social partner and seemed to benefit more from extended social exposure than their SS counterparts. The MS females were more similar to wild-born females than were SS females in nearly every behavior category and dimension tested. These results suggest that rearing with mobile artificial mothers improves the chances of later adaptive social adjustments in socially restricted monkeys.
Collapse
|
46
|
|
47
|
Kenney AM, Evans RL, Dewsbury DA. Postimplantation pregnancy disruption in Microtus ochrogaster, M. pennsulvanicus and Peromyscus maniculatus. J Reprod Fertil 1977; 49:365-7. [PMID: 321775 DOI: 10.1530/jrf.0.0490365] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
48
|
Abstract
Six species of muroid rodents (Peromyscus californicus, P. eremicus, P. gossypinus, Mesocricetus auratus, Rattus norvegicus and R. rattus) were given artificlal vaginal-cervical stimulation in an attempt to induce pseudopregnancy. Some females of each species became pseudopregnant, but it was not clear that stimulation patterns mimicking the copulatory patterns of conspecific males were more effective than other patterns of stimulation. In the non-domesticated species (Peromyscus and R. rattus) a few females responded to a variety of stimulus conditions, and no species differences in responsiveness among the wild species were evident. The established laboratory rodents (R. norvegicus, M. auratusy were markedly more responsive to artificial stimulation, suggesting possible effects of domestication on fecundity and reactions to handling- Microtus ochrogaster, an induced ovulator, ovulated in response to vaginal-cervical stimulation only if one intromission from a male was also provided. No other differences in the responses of reflex and spontaneous ovulators were apparent.
Collapse
|
49
|
Gray GD, Davis HN, Kenney AM, Dewsbury DA. Effect of mating on plasma levels of LH and progesterone in montane voles (Microtus montanus). J Reprod Fertil 1976; 47:89-91. [PMID: 775081 DOI: 10.1530/jrf.0.0470089] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
50
|
|