scholarly journals MBRS-63. THE ROLE OF THE SWI/SNF COMPLEX SUBUNIT SMARCD3 IN MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii409-iii409
Author(s):  
Brad Poore ◽  
Han Zou ◽  
Vaibhav Sharma ◽  
Ian Pollack ◽  
Baoli Hu
Keyword(s):  
Regulation Of Gene Expression ◽  
Orthotopic Mouse Model ◽  
Primary Tumors ◽  
Group 4 ◽  
Tumor Dissemination ◽  
Elevated Expression ◽  
Group 3 ◽  
Genomic Regions ◽  
Medulloblastoma Cell Lines

Abstract Medulloblastoma is the most common malignant brain tumor in children, with the Group 3 (G3) having the worst prognosis of the subgroups (WNT, SHH, and Group 4). We aimed to determine the underlying differences between G3 and the other subgroups, with an emphasis on genes that control the epigenome for developing effective treatments for patients with this disease. To this end, we found that G3 has elevated expression of the SWI/SNF subcomponent, SMARCD3 (P<0.001), which serves to guide the SWI/SNF complex to different genomic regions through interactions with various transcription factors. However, little is known about function of SMARCD3 in cancer, particularly in medulloblastoma. Clinically, elevated SMARCD3 mRNA resulted in a poorer prognosis in medulloblastoma patients (P<0.0001), which was further validated in 63 patient tumors by immunohistochemical staining for SMARCD3. Interestingly, tumors that had metastasized often had elevated expression of SMARCD3, in all subgroups of medulloblastomas (P<0.0001) and G3 only (P<0.01) based on analyzing multiple published databases. An orthotopic mouse model further supported that SMARCD3 is highly expressed in metastatic tumors compared to primary tumors. Importantly, CRISPR-CAS9-mediated SMARCD3 deletion decreased cell migration in medulloblastoma cell lines. Mechanistically, SMARCD3 deletion led to decreased H3K27me3, suggesting that SMARCD3 may cooperate with PRC2 in regulation of gene expression. Together, our results indicate that SMARCD3 plays a significant role in the development of metastatic dissemination in medulloblastoma, especially in the G3 subgroup. Thus, targeting the SMARCD3-containing SWI/SNF Complex may effectively prevent tumor dissemination and improve clinical outcomes in children with medulloblastoma.

scholarly journals CSIG-21. BAF60C/SMARCD3 REGULATES TUMOR CELL DISSEMINATION IN MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii32-ii32
Author(s):  
Baoli Hu ◽  
Brad Poore ◽  
Vaibhav Sharma ◽  
Yongchang Guan ◽  
Sameer Agnihotri ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Migration And Invasion ◽  
Orthotopic Mouse Model ◽  
Primary Tumors ◽  
Downstream Signaling ◽  
Tumor Dissemination ◽  
Elevated Expression ◽  
Group 3

Abstract Medulloblastoma, the most common malignant brain tumor in children, is a diverse and heterogeneous disease. Molecular characterization of MB revealed four major subgroups, WNT, SHH, Group 3, and Group 4. Although surgical resection, radiotherapy, and chemotherapy are effective at eliminating some forms, patients with the aggressive tumors cannot be cured with conventional therapies, particularly in Group 3. Group 3 is the most aggressive subtype of this disease, accounting for about 25%-30% of cases, and characterized by frequent metastasis at diagnosis and the worst prognosis among all the subgroups. Metastatic dissemination is a major treatment challenge and strongly associated with poor prognosis in patients with medulloblastoma. However, the molecular mechanisms of tumor cell early dissemination and late metastasis remain largely unknown. Here, we found that Group 3 has elevated expression of BAF60C/SMARCD3, a subcomponent of SWI/SNF complex, which significantly mobilizes nucleosomes and remodels chromatin. Clinically, elevated SMARCD3 mRNA resulted in a poorer prognosis in medulloblastoma patients, which was further validated in 63 patient tumors by immunohistochemical staining for SMARCD3. Interestingly, tumors that had metastasized often had elevated expression of SMARCD3, in all subgroups of medulloblastomas and Group 3 only. An orthotopic mouse model further supported that SMARCD3 is highly expressed in metastatic tumors compared to primary tumors. Importantly, CRISPR-Cas9-mediated SMARCD3 deletion decreased cell migration and invasion in multiple medulloblastoma cell lines. Mechanistically, SMARCD3 deletion led to decreased H3K27me3, suggesting that SMARCD3 may cooperate with PRC2 in regulation of gene expression. Strikingly, SMARCD3 deletion downregulated Reelin signaling pathway, an essential role in neuronal positioning during neurodevelopment, which indicates that tumors with highly expressed SMARCD3 hijack a developmental signaling to promote their dissemination and aggressiveness. Together, our results suggest that inhibition of SMARCD3 controlling downstream signaling may effectively prevent tumor dissemination and improve clinical outcomes in children with medulloblastoma.

scholarly journals MBCL-08. INTEGRATIVE MOLECULAR ANALYSIS OF PATIENT-MATCHED DIAGNOSTIC AND RELAPSED MEDULLOBLASTOMAS

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii389-iii389
Author(s):  
Rahul Kumar ◽  
Maximilian Deng ◽  
Kyle Smith ◽  
Anthony Liu ◽  
Girish Dhall ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Copy Number ◽  
Driver Mutations ◽  
P Value ◽  
Next Generation ◽  
Driver Genes ◽  
Methylation Array ◽  
Primary Tumors ◽  
Group 4 ◽  
Group 3

Abstract INTRODUCTION The next generation of clinical trials for relapsed medulloblastoma demands a thorough understanding of the clinical behavior of relapsed tumors as well as the molecular relationship to their diagnostic counterparts. METHODS A multi-institutional molecular cohort of patient-matched (n=126 patients) diagnostic MBs and relapses/subsequent malignancies was profiled by DNA methylation array. Entity, subgroup classification, and genome-wide copy-number aberrations were assigned while parallel next-generation (whole-exome or targeted panel) sequencing on the majority of the cohort facilitated inference of somatic driver mutations. RESULTS Comprised of WNT (2%), SHH (41%), Group 3 (18%), Group 4 (39%), primary tumors retained subgroup affiliation at relapse with the notable exception of 10% of cases. The majority (8/13) of discrepant classifications were determined to be secondary glioblastomas. Additionally, rare (n=3) subgroup-switching events of Group 4 primary tumors to Group 3 relapses were identified coincident with MYC/MYCN pathway alterations. Amongst truly relapsing MBs, copy-number analyses suggest somatic clonal divergence between primary MBs and their respective relapses with Group 3 (55% of alterations shared) and Group 4 tumors (63% alterations shared) sharing a larger proportion of cytogenetic alterations compared to SHH tumors (42% alterations shared; Chi-square p-value < 0.001). Subgroup- and gene-specific patterns of conservation and divergence amongst putative driver genes were also observed. CONCLUSION Integrated molecular analysis of relapsed MB discloses potential mechanisms underlying treatment failure and disease recurrence while motivating rational implementation of relapse-specific therapies. The degree of genetic divergence between primary and relapsed MBs varied by subgroup but suggested considerably higher conservation than prior estimates.

TMOD-26. MYC OVEREXPRESSION AND SMARCA4 LOSS IN GRANULE CELL PRECURSORS COOPERATE TO DRIVE MEDULLOBLASTOMA FORMATION IN MICE

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi221-vi221
Author(s):  
Carolin Göbel ◽  
Dörthe Holdhof ◽  
Melanie Schoof ◽  
Catena Kresbach ◽  
Ulrich Schüller
Keyword(s):  
Granule Cell ◽  
Clinical Course ◽  
Tumor Development ◽  
Tumor Formation ◽  
Human Group ◽  
Group 4 ◽  
Small Cohort ◽  
Group 3 ◽  
Granule Cell Precursors

Abstract Mutations in SMARCA4 are frequently identified in medulloblastoma, the most common pediatric malignant brain tumor. However, the functional significance of these mutations and their suitability as a therapeutic target remain largely unclear. Medulloblastomas are divided into 4 subgroups according to their localization, molecular biology, and clinical course: WNT, SHH, Group 3, and Group 4. Group 3 medulloblastomas are associated with the poorest outcome and frequently show amplifications of the oncogene MYC. Additionally, SMARCA4 is mutated in around 15 % of cases. The few mouse models developed for this entity so far all involve the overexpression of MYC, mostly in combination with other drivers. However, none of these models include alterations in Smarca4. In our approach, we combined an overexpression of MYC with a loss of SMARCA4 in granule cell precursors, which successfully induced tumor formation in mice. For this purpose, granule cell precursors were isolated from 7-day-old Math1-creER T2 ::Smarca4 fl/fl pups after tamoxifen induced loss of SMARCA4. MYC overexpression was achieved by lentiviral transduction and transduced cells were transplanted into immunodeficient CD1 nu/nu mice. Preliminary results within a small cohort showed tumor formation in 5/19 transplanted mice (26 %) after 6 months. Immunohistochemically, tumors all stained negative for SMARCA4. In a next step, additional cohorts will elucidate if tumor development is indeed accelerated by or even dependent on the loss of SMARCA4. Additionally, the neoplastic potential of tumor cells will be verified with the aid of secondary recipient mice. To evaluate to what extent the generated tumors are comparable to human Group 3 medulloblastomas, tumors will be extensively analyzed on a morphological, transcriptional, and epigenetic level. Altogether, we hope to establish a suitable mouse model for SMARCA4 mutated Group 3 medulloblastoma that will help to elucidate the role of SMARCA4 in tumor development and to identify new therapeutic targets.

scholarly journals Clinical Significance of Circulating Tumor Cells in Gastrointestinal Carcinomas

Diagnostics ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 192
Author(s):  
Leonie Konczalla ◽  
Anna Wöstemeier ◽  
Marius Kemper ◽  
Karl-Frederik Karstens ◽  
Jakob Izbicki ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Clinical Application ◽  
Liquid Biopsy ◽  
Cancer Diagnostics ◽  
Therapeutic Approaches ◽  
Primary Tumors ◽  
New Therapeutic Approaches ◽  
Tumor Dissemination

The idea of a liquid biopsy to screen, surveil and treat cancer patients is an intensively discussed and highly awaited tool in the field of oncology. Despite intensive research in this field, the clinical application has not been implemented yet and further research has to be conducted. However, one component of the liquid biopsy is circulating tumor cells (CTCs) whose potential for clinical application is evaluated in the following. CTCs can shed from primary tumors to the peripheral blood at any time point during the progress of a malignant disease. Following, one single CTC can be the origin for distant metastasis at later cancer stage. Thus, CTCs have great potential to either be used in cancer diagnostics and patient stratification or to function as a target for new therapeutic approaches to stop tumor dissemination and metastasis at the very early beginning. Due to the biological fundamental role of CTCs in tumor progression, here, we provide an overview of CTCs in gastrointestinal cancers and their potential use in the clinical setting. In particular, we discuss the usage of CTC for screening and stratifying patients’ risk. Moreover, we will discuss the potential role of CTCs for treatment specification and treatment monitoring.

P5392Epicardium derived cells promote sympathetic ganglionic outgrowth towards myocardium in vitro

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
Y Ge ◽  
A M Smits ◽  
J C Van Munsteren ◽  
T Van Herwaarden ◽  
A M D Vegh ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Autonomic Innervation ◽  
Cardiac Damage ◽  
Group 4 ◽  
Group 3 ◽  
Cervical Ganglia ◽  
Group 2 ◽  
Group 1

Abstract Background The autonomic nerve system is essential to maintain homeostasis in the body. In the heart, autonomic innervation is important for adjusting the physiology to the continuously changing demands such as stress responses. After cardiac damage, excessive neurite outgrowth, referred to as autonomic hyperinnervation, can occur which is related to ventricular arrhythmias and sudden cardiac death. The cellular basis for this hyperinnervation is as yet unresolved. Here we hypothesize a role for epicardium derived cells (EPDCs) in stimulating sympathetic neurite outgrowth. Purpose To investigate the potential role of adult EPDCs in promoting sympathetic ganglionic outgrowth towards adult myocardium. Method Fetal murine superior cervical ganglia were dissected and co-cultured with activated adult mesenchymal epicardium-derived cells (EPDCs) or/and adult myocardium in a 3D collagen gel culture system. Four experiment groups were included: Group 1: Vehicle cultures (ganglia cultured without EPDC/myocardium) (n=48); Group 2: ganglia co-cultured with EPDCs (n=38); Group 3: ganglia co-cultured with myocardium (n=95); and group 4: ganglia co-cultured with both EPDCs and myocardium (n=96). The occurrence of neurite outgrowth was assessed in each group. The density of neurites that showed directional sprouting (i.e. sprouting towards myocardium) was assessed as well with a semi-automatic quantification method. Finally, sub-analyses were made by taking gender into account. Results Cervical ganglia cultured with EPDCs alone (group 2) showed increased neurite outgrowth compared to vehicle cultures (group 1), however the neurites did not show directional sprouting towards EPDCs. When co-cultured with myocardium (group 3), directional neurite outgrowth towards myocardium was observed. Compared to the ganglia-myocardium co-cultures, directional outgrowth was significantly increased in co-cultures combining myocardium and EPDCs (group 4), and the neurite density was also significantly augmented. Comparison between males and female ganglia demonstrated that more neurite outgrowth occurred in female-derived ganglia than in male-derived ganglia under the same co-culture conditions. Conclusion Activated adult EPDCs promote sympathetic ganglionic outgrowth in vitro. Sex differences exist in the response of ganglia to EPDCs, and female-derived ganglia appear more sensitive to EPDC-signalling. Results support a role of EPDCs in cardiac autonomic innervation and open avenues for exploring of their role in ventricular hyperinnervation after cardiac damage.

Experimental model of posttraumatic syringomyelia: the role of adhesive arachnoiditis in syrinx formation

1994 ◽  
Vol 80 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Ki Hong Cho ◽  
Yoshinobu Iwasaki ◽  
Hiroyuki Imamura ◽  
Kazutoshi Hida ◽  
Hiroshi Abe
Keyword(s):  
Normal Saline ◽  
Subarachnoid Space ◽  
Saline Solution ◽  
Traumatic Injury ◽  
Content Type ◽  
Group 4 ◽  
Kaolin Injection ◽  
Group 3 ◽  
Group 2

✓ An experimental model was devised to elucidate the role of spinal blockade in posttraumatic syringomyelia. Thirty-eight Japanese White rabbits, each weighing about 3 kg, were used in this study. The animals were divided into four groups: in Group 1, eight animals received traumatic injury only; in Group 2, 12 animals received traumatic injury following injection of 100 mg kaolin suspended in 1 cc normal saline solution into the subarachnoid space at the site of trauma; in Group 3, nine animals received traumatic injury following injection of 200 mg kaolin in 1 cc normal saline solution into the subarachnoid space at the site of trauma; and in Group 4, nine animals without traumatic injury received an injection of 200 mg kaolin in 1 cc normal saline solution into the subarachnoid space. The subjective criteria for syrinx formation were the presence of a definite round cyst having a smooth margin and an upper or lower extension of more than 2 cm from the injured site. Syrinx formation was seen in 12.5% (one of eight rabbits) in Group 1, 41.7% (five of 12 animals) in Group 2, 55.5% (five of nine rabbits) in Group 3 and 0% (none of nine animals) in Group 4 (p < 0.05). There was a tendency for the combined trauma/kaolin injection groups to be more prone to develop a syrinx. In the kaolin injection only group (Group 4), no animal showed a definite cyst or an extending cavity during the experimental period. The results suggest that kaolin enhances the extension of multiple small cavities that have already formed at the time of initial injury. The difference between the frequency of syrinx formation and the time of survival was statistically significant well beyond the 0.05% level. The overall difference, relating to the frequency of syrinx development, group, and duration of survival, was also statistically significant. In summary, subarachnoid block secondary to adhesive arachnoiditis is important in initiating the extension of the syringomyelia cavity.

scholarly journals Preclinical Models of Craniospinal Irradiation for Medulloblastoma

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 133 ◽  
Author(s):  
Jennifer L. Stripay ◽  
Thomas E. Merchant ◽  
Martine F. Roussel ◽  
Christopher L. Tinkle
Keyword(s):  
Small Animal ◽  
Craniospinal Irradiation ◽  
Tumor Control ◽  
Preclinical Models ◽  
Treatment Interventions ◽  
Leptomeningeal Seeding ◽  
Group 4 ◽  
Pediatric Medulloblastoma ◽  
Group 3

Medulloblastoma is an embryonal tumor that shows a predilection for distant metastatic spread and leptomeningeal seeding. For most patients, optimal management of medulloblastoma includes maximum safe resection followed by adjuvant craniospinal irradiation (CSI) and chemotherapy. Although CSI is crucial in treating medulloblastoma, the realization that medulloblastoma is a heterogeneous disease comprising four distinct molecular subgroups (wingless [WNT], sonic hedgehog [SHH], Group 3 [G3], and Group 4 [G4]) with distinct clinical characteristics and prognoses has refocused efforts to better define the optimal role of CSI within and across disease subgroups. The ability to deliver clinically relevant CSI to preclinical models of medulloblastoma offers the potential to study radiation dose and volume effects on tumor control and toxicity in these subgroups and to identify subgroup-specific combination adjuvant therapies. Recent efforts have employed commercial image-guided small animal irradiation systems as well as custom approaches to deliver accurate and reproducible fractionated CSI in various preclinical models of medulloblastoma. Here, we provide an overview of the current clinical indications for, and technical aspects of, irradiation of pediatric medulloblastoma. We then review the current literature on preclinical modeling of and treatment interventions for medulloblastoma and conclude with a summary of challenges in the field of preclinical modeling of CSI for the treatment of leptomeningeal seeding tumors.

scholarly journals Evaluation of protective effect of myricetin, a bioflavonoid in dimethyl benzanthracene-induced breast cancer in female Wistar rats

2014 ◽  
Vol 03 (02) ◽  
pp. 107-111 ◽  
Author(s):  
J. K. Jayakumar ◽  
P. Nirmala ◽  
B.A. Praveen Kumar ◽  
Ashok P. Kumar
Keyword(s):  
Breast Cancer ◽  
Wistar Rats ◽  
Statistical Significance ◽  
Treated Animal ◽  
Group 4 ◽  
Female Wistar Rats ◽  
Group 3 ◽  
Group 2 ◽  
And Control

Abstract Background: Breast cancer is one of the most common cancers worldwide. Alarmingly, the incidence of breast cancer is rising rapidly in India. Aim: The present research was focused to assess the role of myricetin; a bioflavonoid in 7,12-dimethylbenzanthracene (DMBA)-induced breast cancer in female Wistar rats. Materials and Methods: A total of 36 female Wistar rats (total 6 groups, n = 6 per group) 6 - 8 weeks old, weighing 150 gm were used in the study. DMBA was given at the dose of 7.5 mg/kg subcutaneously in the mammary region once a week for 4 consecutive weeks in group 2. Vincristine was given in the dose of 500 μg/kg intraperitonially every week for 4 consecutive weeks in group 3. Myricetin was given orally in a dose of 50, 100, and 200 mg/kg in group 4, 5, and 6 respectively. The statistical significance of the data was determined using one way analysis of variance and Duncan’s multiple range test. Results: The result showed that myricetin increased the antioxidant levels in plasma, erythrocyte lysate, and breast tissue and was effective in preventing the oxidative damage induced by the carcinogen DMBA. Myricetin 50, 100, and 200 mg/kg/oral for 120 days treated animal resulted comparable results to that of standard vincristine and control groups. Conclusions: Myricetin was found to be either equieffective or more effective than vincristine in all the parameters studied. Myricetin proved the capacity of flavonols to act as antioxidant in cells represents a potential treatment in the field of oncology.

The state of thrombotic readiness in rats at suprathreshold physical load and its correction by products of velvet antler industry

2018 ◽  
Author(s):  
А.А. Блажко ◽  
И.И. Шахматов ◽  
И.В. Ковалев ◽  
Ю.А. Бондарчук ◽  
О.М. Улитина ◽  
...  
Keyword(s):  
Reproductive Organs ◽  
Physical Load ◽  
Internal Organs ◽  
Group 4 ◽  
Partial Activation ◽  
Velvet Antler ◽  
Male Wistar Rats ◽  
Body Resistance ◽  
Group 3

Введение. При действии чрезмерных стрессоров различной природы система гемостаза может отвечать формированием состояния тромботической готовности, а чтобы избежать его развития необходимо повышать устойчивость организма и, в частности, системы гемостаза к стрессорным воздействиям. Одним из способов является применение продуктов пантового оленеводства. Цель исследования: оценить состояние системы гемостаза у крыс при однократной сверхпороговой физической нагрузке разной продолжительности, а также определить адаптационную роль предварительного курсового приема концентрата, содержащего кровь и гистолизат из репродуктивных органов марала. Материалы и методы. Исследования выполнены на 50 крысах-самцах линии Wistar: 4 экспериментальные группы и группа интактных животных по 10 крыс. Животных групп 1 и 2 подвергали 4-часовой и 8-часовой физической нагрузке, соответственно. Животные группы 3 принимали продукты пантового оленеводства (концентрат) в течение 30 дней и на 31-й день подвергались 8-часовой физической нагрузке. Животные группы 4 принимали концентрат в течение 30 дней и не подвергались воздействию физической нагрузки. Интактные крысы принимали воду в том же объеме, что и экспериментальные животные, и не подвергались воздействию физической нагрузки. Состояние системы гемостаза оценивали методом тромбоэластографии. Проведено гистологическое исследование легких крыс во всех группах. Результаты. 4-часовая физическая нагрузка вызывала частичную активацию системы гемостаза у крыс, усиливая наступление фазы инициации свертывания крови. 8-часовая физическая нагрузка вызывала у крыс развитие состояния тромботической готовности. Заключение. Предварительный курсовой прием продуктов пантового оленеводства снижал риск развития состояния тромботической готовности и повреждения внутренних органов у крыс после сверхпороговой физической нагрузки за счет повышения фибринолитической активности плазмы крови. Introduction. Under the action of excessive stressors of diff erent nature, hemostasis can respond by forming a state of thrombotic readiness. In order to avoid its development, it is necessary to increase body resistance and hemostasis in particular to stress eff ects. One of the methods is the usage of the products of velvet antler industry. Aim: to assess hemostasis in rats at a single suprathreshold physical load of different duration and to determine the adaptive role of preliminary intake of a concentrate containing blood and histolysate from maral reproductive organs. Materials and methods. Studies were performed on 50 male Wistar rats: 4 experimental groups and a group of intact animals, 10 rats each. Animals of groups 1 and 2 were exposed to 4-hour and 8-hour physical load, respectively. Animals of group 3 received products of velvet antler industry (concentrate) for 30 days and on 31st day were exposed to 8-hour suprathreshold physical load. Animals of group 4 received a concentrate for 30 days and were not exposed to physical stress. Intact rats took water in the same volume as experimental animals and were not exposed to physical activity. Hemostasis was assessed by thromboelastography. Histological examination of lungs was carried out in rats from all groups. Results. The 4-hour physical load caused partial activation of hemostasis, enhancing the phase onset of blood coagulation. The 8-hour physical load caused the development of thrombotic readiness. Conclusion. Preliminary intake of velvet antler products reduced the risk of thrombotic readiness development and damage of internal organs in rats after suprathreshold physical load due to increasing of blood fibrinolytic activity.

scholarly journals Role of protein arginine methyltransferase 5 in group 3 (MYC-driven) Medulloblastoma

BMC Cancer ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Nagendra K. Chaturvedi ◽  
Sidharth Mahapatra ◽  
Varun Kesherwani ◽  
Matthew J. Kling ◽  
Mamta Shukla ◽  
...  
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Therapeutic Potential ◽  
Physical Interaction ◽  
Methyl Transferase ◽  
Primary Tumors ◽  
Expression Levels ◽  
Group 3

Abstract Background MYC amplification or overexpression is common in Group 3 medulloblastoma and is associated with the worst prognosis. Recently, protein arginine methyl transferase (PRMT) 5 expression has been closely associated with aberrant MYC function in various cancers, including brain tumors such as glioblastoma. However, the role of PRMT5 and its association with MYC in medulloblastoma have not been explored. Here, we report the role of PRMT5 as a novel regulator of MYC and implicate PRMT5 as a potential therapeutic target in MYC-driven medulloblastoma. Methods Expression and association between PRMT5 and MYC in primary medulloblastoma tumors were investigated using publicly available databases. Expression levels of PRMT5 protein were also examined using medulloblastoma cell lines and primary tumors by western blotting and immunohistochemistry, respectively. Using MYC-driven medulloblastoma cells, we examined the physical interaction between PRMT5 and MYC by co-immunoprecipitation and co-localization experiments. To determine the functional role of PRMT5 in MYC-driven medulloblastoma, PRMT5 was knocked-down in MYC-amplified cells using siRNA and the consequences of knockdown on cell growth and MYC expression/stability were investigated. In vitro therapeutic potential of PRMT5 in medulloblastoma was also evaluated using a small molecule inhibitor, EPZ015666. Results We observed overexpression of PRMT5 in MYC-driven primary medulloblastoma tumors and cell lines compared to non-MYC medulloblastoma tumors and adjacent normal tissues. We also found that high expression of PRMT5 is inversely correlated with patient survival. Knockdown of PRMT5 using siRNA in MYC-driven medulloblastoma cells significantly decreased cell growth and MYC expression. Mechanistically, we found that PRMT5 physically associated with MYC by direct protein-protein interaction. In addition, a cycloheximide chase experiment showed that PRMT5 post-translationally regulated MYC stability. In the context of therapeutics, we observed dose-dependent efficacy of PRMT5 inhibitor EPZ015666 in suppressing cell growth and inducing apoptosis in MYC-driven medulloblastoma cells. Further, the expression levels of PRMT5 and MYC protein were downregulated upon EPZ015666 treatment. We also observed a superior efficacy of this inhibitor against MYC-amplified medulloblastoma cells compared to non-MYC-amplified medulloblastoma cells, indicating specificity. Conclusion Our results reveal the regulation of MYC oncoprotein by PRMT5 and suggest that targeting PRMT5 could be a potential therapeutic strategy for MYC-driven medulloblastoma.

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