13 research outputs found
Hsa-miRNA-765 as a key mediator for inhibiting growth, migration and invasion in fulvestrant-treated prostate cancer
Fulvestrant (ICI-182,780) has recently been shown to effectively suppress prostate cancer cell growth in vitro and in vivo. But it is unclear whether microRNAs play a role in regulating oncogene expression in fulvestrant-treated prostate cancer. Here, this study reports hsa-miR-765 as the first fulvestrant-driven, ERβ-regulated miRNA exhibiting significant tumor suppressor activities like fulvestrant, against prostate cancer cell growth via blockage of cell-cycle progression at the G2/M transition, and cell migration and invasion possibly via reduction of filopodia/intense stress-fiber formation. Fulvestrant was shown to upregulate hsa-miR-765 expression through recruitment of ERβ to the 5′-regulatory-region of hsa-miR-765. HMGA1, an oncogenic protein in prostate cancer, was identified as a downstream target of hsa-miR-765 and fulvestrant in cell-based experiments and a clinical study. Both the antiestrogen and the hsa-miR-765 mimic suppressed HMGA1 protein expression. In a neo-adjuvant study, levels of hsa-miR-765 were increased and HMGA1 expression was almost completely lost in prostate cancer specimens from patients treated with a single dose (250 mg) of fulvestrant 28 days before prostatectomy. These findings reveal a novel fulvestrant signaling cascade involving ERβ-mediated transcriptional upregulation of hsa-miR-765 that suppresses HMGA1 protein expression as part of the mechanism underlying the tumor suppressor action of fulvestrant in prostate cancer. © 2014 Leung et al
<i>Hsa-miR-765</i> suppresses DU145 cell growth, migration, and invasion.
<p>(A) <i>Hsa-miR-765</i> mimic effectively recognizes reporter with complementary sequence of <i>hsa-miR-765</i> in DU145 cells. Fold changes of luciferase activities of the <i>hsa-miR-765</i> mimic treated cells relative to the cells treated with the negative-control mimic are presented (n = 3). Transfection reagents were used as control. (B) <i>Hsa-miR-765</i> mimic reduces DU145 cell growth. MTS assay was performed on the cells treated with <i>hsa-miR-765</i> mimic or negative-control mimic or transfection control for 4 days (n = 8). (C) <i>Hsa-miR-765</i> mimic significant reduces G0/G1 to G2/M ratio in DU145. Representative DNA histograms (n = 3) are presented. (D) <i>Hsa-miR-765</i> mimic treatment causes up-regulation of cyclin A, cyclin B, and phosphorylated-cdc2 expression in DU145 cells. Protein expression levels of cell cycle regulator proteins were determined by Western blot analyses. Two independent experiments were performed and one representative set of data was presented. (E) <i>Hsa-miR-765</i> mimic suppresses DU145 cell migration and invasion as shown in transwell migration assay (top left) and invasion assay (top right), respectively. Representative micrographs of the cells after transwell migration (top left) or invasion assay (top right) are presented. Fold changes of migration (bottom left) and invasion (bottom right) of DU145 cells with either <i>hsa-miR-765</i> mimic or negative-control mimic relative to the control cells with negative-control mimic are presented (n = 3). (F) <i>Hsa-miR-765</i> mimic significantly reduces stress fibers and filopodia formations in DU145 cells. Representative micrographs and the percentages of the cells with intense stress fibers and the filopodial cells (n = 3) are presented. Student's t-test was used for comparisons with a cutoff p value of 0.05. ** p<0.01; bar = S.D.</p
HMGA1 is a direct target of <i>hsa-miR-765</i>.
<p>(A) The 3′UTR of <i>HMGA1</i> from +8910 to +8929 is predicted to be <i>hsa-miR-765</i> binding site. (B) <i>Hsa-miR-765</i> interacts with 3′UTR of <i>HMGA1</i> in a targeting reporter assay. DU145 cells were transfected with either pMIR-empty or pMIR-HMGA1-3UTR in which 3′ UTR of <i>HMGA1</i> (+8026–+9332) was cloned into the 3′ end of luciferase. Reporter activities of the pMIR-HMGA1-3UTR transfected cells treated with <i>hsa-miR-765</i> mimic or negative-control mimic are compared (n = 3). (C) <i>Hsa-miR-765</i> mimic reduced HMGA1 protein expression in DU145 cells. Protein and mRNA levels of HMGA1 in the <i>hsa-miR-765</i> mimic- and negative-control mimic-treated cells were determined by Western blot analysis (upper) and real-time RT-PCR analysis (lower), respectively. Results from <i>miR-765</i> mimic vs negative control mimic are compared (n = 3). (D) Fulvestrant reduces HMGA1 protein expression in DU145 cells. Protein level of HMGA1 and β-actin in the fulvestrant-treated and ethanol-treated control (CTL) cells were determined by Western blot analysis. (E) Ectopic expression of HMGA1 blocks fulvestrant-induced DU145 cell growth inhibition. The relative cell growth was determined after 4 days of treatment with fulvestrant or ethanol after stable transfection of <i>HMGA1</i> (or empty vector for control) for a week. Protein levels of HMGA1 were shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098037#pone.0098037.s006" target="_blank">Figure S6</a>. The cell growth of fulvestrant-treated cells with HMGA1 overexpression vs empty vector are compared (n = 8). Student's t-test was performed to determine significance between groups using a cutoff p value of 0.05. **p<0.01; bar = S.D.</p
Fulvestrant inhibits DU145 cell growth, migration, and invasion.
<p>(A) Fulvestrant induces growth inhibition of DU145 cells via an ERβ-dependent mechanism. Growth of the fulvestrant-treated DU145 cells with or without ERβ siRNA knockdown for 4 days relative to the ethanol-treated control cells with negative-control siRNA are presented and compared (n = 8). ERβ expression was also knocked down by another siRNA (siRNA#2) and the similar results were obtained (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098037#pone.0098037.s005" target="_blank">Figure S5</a>). (B) Fulvestrant induces DU145 cell-cycle arrest at G2/M phase. Representative DNA histograms of 48 hrs fulvestrant -or ethanol- (control) treated cells and percentage distributions of the cells at G0/G1 and G2/M phases (n = 3) are presented and compared. (C) Fulvestrant induces expression of G2/M markers. DU145 cells were treated with fulvestrant or ethanol for 2 days (control) and cell cycle markers were determined by Western blot analysis. Two independent experiments were performed and one representative set of data was presented. (D) Fulvestrant suppresses cell migration. A wound-healing assay was performed on the fulvestrant- and ethanol (EtOH)-treated DU145 cells (n = 3). Representative micrographs of the fulvestrant- and ethanol-treated cell cultures with scratches at 0 h and after 16 h are shown. The wound is marked by dotted lines. (E) Fulvestrant inhibits transwell migration (left panel) and invasion (right panel) in DU145 cells (n = 3) after 5 hrs of fulvestrant treatment. (F) Reductions of filopodial cells and cells with intense stress fibers by fulvestrant (treated with 48 hrs) via an ERβ-dependent mechanism. Representative micrographs and the percentages of the cells with intense stress fibers and the filopodial cells (n = 3) are presented. Student t-test was performed to determine significance with a cutoff p value of 0.05. ** p<0.01; bars = S.D.</p
ERβ is involved in fulvestrant-induced upregulation of <i>hsa-miR-765</i> expression.
<p>(A) ERβ siRNA knockdown blocks fulvestrant-induced upregulation of <i>hsa-miR-765</i> expression in DU145 cells. Expression levels of <i>hsa-miR-765</i> determined by qRT-PCR analysis of the fulvestrant-treated cells with ERβ-siRNA (siERβ) or scramble negative-control (siNeg) were compared (n = 3). (B) SiRNA knockdown of ERβ blocks fulvestrant-induced transactivation of the 5′ upstream regulatory region of <i>hsa-miR-765</i> in DU145 cells. 5′ upstream regulatory region of <i>hsa-miR-765</i> was cloned into a luciferase vector. The reporter activities with ERβ-knockdown (siERβ) or scramble negative-control (siNeg) in the presence of fulvestrant were compared (n = 3). (C) Deletion mapping analysis defines a fulvestrant-responsive segment in <i>hsa-miR-765</i> regulatory region in DU145 cells. The 5′ upstream DNA sequence of <i>hsa-miR-765</i> from nt. −3208 to +100 was analyzed using luciferase reporter system. Serial deletions from the 5′ end of the cloned sequence in the vector were conducted. Reporter activities were compared between the fulvestrant-treated (Fulvestrant) and control (ETOH) cells for each reporter vector (n = 3). (D) Fulvestrant-induces recruitment of ERβ onto the putative <i>hsa-miR-765</i> regulatory region. Chromatin-immunoprecipitation revealed the recruitment of ERβ to a sequence in the 5′-regulatory region of <i>hsa-miR765</i>. Mouse IgG and RNA polymerase II serve as negative and positive control, respectively. Fulvestrant induced 17 fold increase in ERβ recruitment when compared with non-ERβ binding region (the 0N promoter of ERβ <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098037#pone.0098037-Zhu1" target="_blank">[33]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098037#pone.0098037-Fernandes1" target="_blank">[41]</a>). Student's t-test was performed to determine significance of between groups using a cutoff p value of 0.05. ** p<0.01; bar = S.D.</p
Significant reduction of HMGA1 protein correlates with enhanced expression of <i>hsa-miR-765</i> in fulvestrant-treated clinical PCa specimens.
<p>(A) Higher level of <i>hsa-miR-765</i> is detected in fulvestrant-treated clinical PCa specimens. Relative fold changes between expression of <i>hsa-miR-765</i> in the fulvestrant-treated (n = 7) and untreated (n = 7) clinical specimen are presented. Student's t-test was performed to determine significance between two groups. *p<0.05; bar = S.E.M. (B) Nuclear expression of HMGA1 and AR is reduced in fulvestrant-treated clinical PCa specimens. HMGA1 immunostaining was performed in the clinical PCa specimens from the fulvestrant-treated (n = 5) and untreated (n = 5) patients. Representative micrographs (100×) are shown. In upper panel, a magnified view (400×) of a selected region (dashed rectangle) in each micrograph is shown as a small insert to show the immunostaining of HGMA1 in the nuclei of Gleason grade 3/4 cancer foci. Imunnopositivity of nuclear AR is reduced in fulvestrant-treated Gleason grade 3/4 foci as shown in lower panel (400×). (C) Expression of both HMGA1 and AR is significantly reduced in fulvestrant-treated clinical PCa specimens when compared with their respective untreated samples (*p<0.05; **p<0.01; n = 9 (from 5 patients) for untreated samples; n = 10 (from 5 patients) for fulvestrant-treated samples, bar = S.E.M).</p
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MEDULLOBLASTOMA
BACKGROUND: LMD in children with recurrent medulloblastoma and other PNETs carries a poor prognosis and novel therapies are urgently needed to improve disease control. Somatostatin receptor-2 (SSR-2)is overexpressed in medulloblastoma and other central PNETs and can serve as a target for radionuclide tagged somatostatin analogues like 177Lu-DOTA-TATE that has shown considerable efficacy in adults with SSR-2 positive neuro-endocrine tumors. As a preliminary step prior to testing this agent in children with LMD, we performed an efficacy study of i.t. 177Lu-DOTA-TATE in athymic rats bearing LMD from MBL. METHODS: The subarachnoid space was accessed through the animal's cervical spine and a catheter was threaded along the dorsal aspect of spinal cord to the lumbar region and injected with 1 x 107 D341 human MBL cells and treatment initiated 3 days later. Groups of 10 animals received a single i.t. dose of 2, 3, or 5 mCi of 177Lu- DOTA-TATE or saline control. Animals were followed 300 days for survival. RESULTS: Treatment with 2 mCi resulted in an increase in median survival of 58.3% compared with saline control (p < 0.001). Treatment with 5.0 mCi of 177Lu-DOTA-TATE increased median survival by 75.0% compared with the saline control group while a single dose of 3.0 mCi 177Lu-DOTA-TATE increased median survival compared with saline controls by 519.4%. Long-term survivors were seen in 0 of 10 animals treated with saline, 4 of 11 treated with 3 mCi, and 3 of 12 treated with 5.0 mCi. CONCLUSION: Intrathecal 177Lu- DOTA TATE is efficacious in controlling LMD from medulloblastoma in athymic rats. A phase I trial of this agent is being planned in children with LMD from recurrent MBL and other CNS PNETs. INTRODUCTION: Medulloblastoma/PNET is the most common malignant brain tumor in children. For children older than 3 years, the treatment of high risk group includes surgery, craniospinal (CSI) radiation therapy (30-36 Gy) plus local boost radiotherapy (54-56 Gy) and adjuvant chemotherapy, such as cisplatinum, carboplatin, lomustine, cyclophosphamide, and vincristine. The results have demonstrated 5-year overall survival (OS) of 40-60%. This study aimed to evaluate the outcomes of high risk medulloblastoma/PNET patients who were treated with radiation and adjuvant chemotherapy. METHODS: Patients were diagnosed with high risk medulloblastoma/PNET according to the histopathology, medulloblastoma risk classification by an evidence of metastasis or the residual tumor more than 1.5 cm2 and evidence of residual tumor after surgery in PNET. Treatment protocol was CSI RT 36 Gy with local boost at tumor 54-56 Gy. Two to four weeks after RT, patients received 8 courses of chemotherapy consisting of cyclophosphamide 800 mg/m2, day 1-3 and vincristine 2 mg/m2, week 1-3, alternated with carboplatin 200 mg/m2, day 1-3 and etoposide 150 mg/m2, day 1-3. RESULTS: Total of 25 patients, male: female of 2.6:1 and mean ± SD for age of 9.7± 3.0 years, were enrolled. The 5-year progression free survival and OS were 41.6± 11.7% and 61.5± 12.9%,respectively. The age and sex did not determine the difference in outcomes. The hematotoxic side effect, according to the National Cancer Institute's Common Terminology Criteria, were grade 4 leucopenia 60%, grade 4 neutropenia 60%, grade 4 anemia 20%, grade 4 thrombocytopenia 16%, grade 3 leucopenia 20%, grade 3 neutropenia 20%, grade 3 anemia 40%, and grade 3 thrombocytopenia 36%. Febrile neutropenia was found in 11 patients (44%). CONCLUSION: The present study demonstrated the similar outcomes of high risk medulloblastoma/PNET with the previous studies. Although, the grade 3 and 4 hematologic toxicity was high, no treatment related death was found. OBJECTIVE: Recent investigations revealed an association between transcriptional subtypes and morphological features in medulloblastoma. Since both characteristics are of prognostic significance, a precise correlation between them should be well established. Therefore we re-examined paediatric nodular medulloblastoma tumours for correlation with molecular subtypes of disease. METHODS: Paediatric patients with previously diagnosed desmoplastic/nodular (D/N) or medulloblastoma with extensive nodularity (MBEN) histopathology were re-analysed by two neuropathologists. In addition to H&E-stained slides, reticulin preparations were simultaneously analysed from the same FFPE blocks. For identification of transcriptional subtypes of tumours immunohistopathological analyses were performed using a panel of representative antibodies. MYCC amplification was detected by FISH. RESULTS: Altogether 28 tumours with original MBEN or D/N diagnosis where molecular subtypes could be determined were identified. All tumours with MBEN histology belonged to SHH group and displayed distinctive reticulin-positive internodular reaction. However, only ∼60% of tumours with original D/N diagnosis were reticulin-positive. They belonged to SHH type, were mainly infantile and patients are still alive. Among reticulin-negative tumours only two were of the SHH type and were subsequently reclassified as classic and anaplastic tumours with pseudonodules. Importantly, all remaining reticulin-negative tumours with a presence of nodules in H&E staining belonged to the non-WNT,SHH type. Therefore the original diagnosis was again reclassified as classic or anaplastic tumours with pseudonodules. Patients from this group were only males, with median age 14 years old, one had MYCC amplification and two of them died because of disease. Therefore, non-WNT,SHH tumours did not display typical desmoplastic/nodular histology accompanied by reticulin positive reaction as opposite to truly D/N tumours being typical for SHH molecular group (p < 0.001). CONCLUSION: Reticulin staining is necessary to distinguish two different biologically and clinically group of nodular tumours which appear morphologically similar under H&E staining alone. BACKGROUND: In the PNET4 European randomised controlled trial, children with standard risk medulloblastoma were allocated to HFRT or to STRT. All received maintenance chemotherapy. Event-free survival was similar between the two treatment arms. HFRT was associated with worse growth and better questionnaire-based executive function 6.1 years post-diagnosis, especially in children aged <8 years at diagnosis (Kennedy et al., IJROBP, 2014). Therefore the aim of this study was to compare cognitive outcomes between treatment arms. METHODS: Neuropsychological data was collected prospectively in 137 patients from Germany, France, Italy and Sweden. Using results of the Wechsler Intelligence Scales, Kaufman Assessment Battery for Children, and Raven's progressive matrices, we generated: Full scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ), working memory index (WMI) and speed of processing index (PSI). RESULTS: Among the 137 participants, [n = 71 HFRT, n = 66 STRT, 63.5% males; mean (SD, range) age at diagnosis 9.3 years (3.2, 4 to 17.6), 40.9% aged <8 years at diagnosis; age at assessment 15.6 years (3.7, 8.3 to 25). Mean (SD, range) FSIQ in all participants was 88 (19, 40-137); mean intergroup difference [95% CIs] (3.88, [-2.66 to 10.41], p = .24). No difference was found in children aged > 8 years at diagnosis. In children aged <8 at diagnosis, VIQ was significantly higher in children receiving HFRT compared to STRT; a similar trend was found for PSI but not for PIQ,WMI and FSIQ (mean inter-group differences [95% CIs]): VIQ 12.02 [2.37 to 21.67], p = 0.02; PIQ (2.73 [-7.89 to 13.35], p > .10); WMI (5.20 [-2.07 to 12.47], p > .10), PSI (10.91 [-1.54 to 23.36], p = .08; FSIQ (5.28 [-4.23 to 14.79], p > .10). CONCLUSION: HFRT was associated with higher verbal IQ in children aged <8 years at diagnosis, consistent with the previous report using questionnaire-based data. Effect sizes were small, albeit with 10 point inter-group differences within their 95% CIs. Preoperative chemotherapy is often used in pediatric oncology to treat metastatic disease and facilitate the surgery of the primary tumor, but not for brain tumors. A first pilot study showed in 2004 the feasibility and effectiveness of preoperative chemotherapy in treating high-risk medulloblastomas. Seventy-one patients were treated for a metastatic medulloblastoma between 2002 and 2010 at Gustave Roussy. Two strategies were compared in intention to treat. Forty-two children were operated at the time of the diagnosis (group A) and the 29 others children were treated with 2 courses of carboplatin and etoposide (group B) after histological diagnosis (biopsy) and before a delayed surgery. Children of group A received the two courses of carboplatin and etoposide afterwards. The rest of the protocol (high-dose chemotherapy and cranio-spinal irradiation) was similar in the both groups. Complete neuropsychological testing, including intelligence quotient measurements, was scheduled before surgery, before radiotherapy and every year thereafter. MRI performed after neo-adjuvant chemotherapy showed an objective response in 24 patients (83%) and a stable disease in 4 patients (14%). Complete excision rate was significantly higher in group B (100% versus 64%, p = 0.00248) without any difference in postoperative complication rate. Medulloblastoma cells could still be evidenced despite preoperative chemotherapy. The median Total Intelligence Quotient (TIQ) was 81 and 90 in group A and B respectively (p = 0.02543). This difference was even more significant in young children (77 vs 91 points for groupe A and B, respectively). Hydrocephalus and brain radiotherapy dose were not associated with TIQ. Neo-adjuvant chemotherapy had no negative impact on local disease control (79 versus 83%). Event-free survival and overall survival at 3 years were 54 versus 62% and 58 versus 68% respectively (p = NS). Neo-adjuvant chemotherapy in metastatic medulloblastoma is safe and could have a positive impact on neuropsychological outcome and completeness of surgery. BACKGROUND: We prospectively evaluated histopathological findings and molecular variables, which have shown to impact prognosis of medulloblastoma patients, for outcome prediction in homogenously treated metastatic medulloblastoma patients. METHODS: One hundred twenty-three patients aged 4-21 years, diagnosed from 2001 to 2007, received systemic induction chemotherapy and intraventricular methotrexate, followed by hyperfractionated radiotherapy, and maintenance chemotherapy. From 86 patients paraffin material was available for immunohistochemical analysis to determine the activation status of the wingless (WNT) pathway, by immunostaining for β-catenin and sequencing of CTNNB1. In 81 of those 86 patients, material was available for gene amplification assessment of MYCC and MYCN by multiplex ligation-dependent probe amplification. RESULTS: Tumors with nuclear β-catenin immunopositivity showed excellent outcome (n = 4, all classic histology, 3 / 4 with CTNNB1 mutation; 5-year event-free (EFS) and overall survival (OS): 100%) compared to patients with tumors lacking nuclear β-catenin staining (n = 82; 5-year rates: 63% and 72%, respectively; p = 0.134 for EFS, p = 0.213 for OS). Patients with tumors characterized by MYC amplification (n = 5; MYCC, n = 2; MYCN, n = 3; all classic histology despite one case with MYCC amplification showing large cell histology) had poor outcome (20% for EFS and OS, respectively) when compared to patients with non-MYCC/MYCN amplified tumors (n = 76; 5-year EFS and OS: 65% and 75%, respectively; p = 0.011 for EFS, p < 0.001 for OS). Based on histopathological and molecular findings, we identified three risk groups: Favorable- (β-catenin nucleopositive and/or desmoplastic histology (n = 7; one death of disease), n = 11; 5-year EFS and OS 89 ± 11%), poor- (MYCC/MYCN amplification and/or anaplastic or large cell histology, n = 6; 5-year EFS and OS 33 ± 19%), and intermediate-risk group (n = 64; 5-year EFS and OS 61 ± 7%, and 72 ± 6%, respectively; p = 0.020 for EFS, and p = 0.002 for OS). CONCLUSION: Histopathological subtyping together with molecular features (WNT pathway and MYCC/MYCN amplification status) differentiate three risk groups in homogenously treated metastatic medulloblastoma patients. Supported by Deutsche Kinderkrebsstiftung. BACKGROUND: A number of different second neoplasms have been reported in patients with neuroblastoma including brain tumors. None of these second cancers have occurred with sufficient frequency to indicate a specific relationship between neuroblastoma and any other neoplasm except in rare cancer syndromes. OBJECTIVE: We report a case of medulloblastoma in a child 5 months after successful treatment of metastatic neuroblastoma. DESIGN AND METHOD: A MEDLINE search was conducted for queries including “Children”, “medulloblastoma” and ‘neuroblastoma”. Relevant papers were selected for literature review. RESULT: A 10 months old female presented with 2-month history of right eye proptosis. CT scan of the abdomen showed a right adrenal mass with liver metastasis. Brain MRI revealed disease at the right orbital fossa extends to middle cranial fossa with no intracranial disease. Pathology of the right adrenal mass confirmed neuroblastoma with non amplified N myc. The patient was classified as intermediate risk disease and started on chemotherapy consisted of vincristine, cyclophosphamide, cisplatin, dacarbazine, ifosphamide and Adriamycin followed by 5 cycles of Accutane. Surveillance MIBG revealed no evidence of residual disease. Five months later, she had a new onset of trouble walking. CT and MRI of the brain showed a mass in the right cerebellar hemisphere with hydrocephalus. Complete Surgical resection of the mass was done and pathology revealed anaplastic medullobastoma. The patient initiated chemoradiation treatment for medulloblastoma. Her treatment was stopped because of disseminated fungal infection. She is currently receiving metronomic therapy with cyclophosphamide and topotecan and has been clinically stable. Molecular genetic tests are pending for familial cancer syndromes. CONCLUSION: We report a case of metachronous medullobastoma after treatment of metastatic neuroblastoma in a two year-old child. The occurrence of metachronous neoplasms is rare and challenging to treat. Cancer familial syndromes like neurofibromatosis type 1 and Simpson-Golabi-Behmel syndrome need to be excluded. Group 3 medulloblastoma with elevated c-MYC has the worst prognoses of the four molecular subgroups. To generate a genetically defined model of this disease, we transformed human fetal cerebellar stem cells with MYC along with hTERT, dominant negative p53 and constitutively active AKT. The resulting xenografts showed morphological similarities to large cell/anaplastic medulloblastoma, leptomeningeal and spinal dissemination, and had a gene expression profile closely aligned with Group 3 primary tumors. Because MYC over-expression leads to increased glutamine metabolism and glutamine addiction in other cancers, we hypothesized that MYC-driven MB would exhibit increased glutamine metabolism and be sensitive inhibitors of glutamine metabolism. In both our human stem cell derived and established medulloblastoma cell lines, MYC expression positively correlates with increased expression of glutaminolytic enzymes. Inhibition of glutamine metabolism was achieved using two glutamine analogs, acivicin and 6-diazo-5-L-norleucine (DON). In our human stem cell models, MYC-transformed cells experienced a significant decrease in proliferation and an increase in apoptosis after acivicin treatment (p < 0.005), while SV40-transformed cells were unaffected. Both compounds also significantly decreased growth and increased apoptosis of the high-MYC MB cell lines D425Med and D283Med. In xenograft experiments using D283Med, fewer mice receiving acivicin developed flank tumors, and the resulting tumors were significantly smaller (80.9 mm3 treated vs 273.8 mm3 untreated). Glutaminase knockdown using short hairpins also significantly decreased growth of D425Med and D283Med. In summary, we present a novel human cerebellar stem cell based model of Group 3 medulloblastoma, and data suggesting that glutamine metabolism may be a therapeutic target in MYC-driven MB
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