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Deshpande K, Martirosian V, Nakamura BN, Das D, Iyer M, Reed M, Shao L, Bamshad D, Buckley NJ, Neman J. SRRM4-mediated REST to REST4 dysregulation promotes tumor growth and neural adaptation in breast cancer leading to brain metastasis. Neuro Oncol 2024; 26:309-322. [PMID: 37716001 PMCID: PMC10836770 DOI: 10.1093/neuonc/noad175] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Indexed: 09/18/2023] Open
Abstract
BACKGROUND Effective control of brain metastasis remains an urgent clinical need due a limited understanding of the mechanisms driving it. Although the gain of neuro-adaptive attributes in breast-to-brain metastases (BBMs) has been described, the mechanisms that govern this neural acclimation and the resulting brain metastasis competency are poorly understood. Herein, we define the role of neural-specific splicing factor Serine/Arginine Repetitive Matrix Protein 4 (SRRM4) in regulating microenvironmental adaptation and brain metastasis colonization in breast cancer cells. METHODS Utilizing pure neuronal cultures and brain-naive and patient-derived BM tumor cells, along with in vivo tumor modeling, we surveyed the early induction of mediators of neural acclimation in tumor cells. RESULTS When SRRM4 is overexpressed in systemic breast cancer cells, there is enhanced BBM leading to poorer overall survival in vivo. Concomitantly, SRRM4 knockdown expression does not provide any advantage in central nervous system metastasis. In addition, reducing SRRM4 expression in breast cancer cells slows down proliferation and increases resistance to chemotherapy. Conversely, when SRRM4/REST4 levels are elevated, tumor cell growth is maintained even in nutrient-deprived conditions. In neuronal coculture, decreasing SRRM4 expression in breast cancer cells impairs their ability to adapt to the brain microenvironment, while increasing SRRM4/RE-1 Silencing Transcription Factor (REST4) levels leads to greater expression of neurotransmitter and synaptic signaling mediators and a significant colonization advantage. CONCLUSIONS Collectively, our findings identify SRRM4 as a regulator of brain metastasis colonization, and a potential therapeutic target in breast cancer.
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Affiliation(s)
- Krutika Deshpande
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA)
| | - Vahan Martirosian
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Brooke N Nakamura
- Division of Gastrointestinal and Liver Diseases, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Diganta Das
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Mukund Iyer
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Max Reed
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Ling Shao
- Division of Gastrointestinal and Liver Diseases, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Daniella Bamshad
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Noel J Buckley
- Department of Psychiatry, University of Oxford, Oxford, UK
| | - Josh Neman
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- USC Brain Tumor Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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Xie D, Wang Z, Sun B, Qu L, Zeng M, Feng L, Guo M, Wang G, Hao J, Zhou G. High frequency of alternative splicing variants of the oncogene Focal Adhesion Kinase in neuroendocrine tumors of the pancreas and breast. Front Med 2023; 17:907-923. [PMID: 37682378 DOI: 10.1007/s11684-023-1009-7] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/17/2023] [Indexed: 09/09/2023]
Abstract
The characteristic genetic abnormality of neuroendocrine neoplasms (NENs), a heterogeneous group of tumors found in various organs, remains to be identified. Here, based on the analysis of the splicing variants of an oncogene Focal Adhesion Kinase (FAK) in The Cancer Genome Atlas datasets that contain 9193 patients of 33 cancer subtypes, we found that Box 6/Box 7-containing FAK variants (FAK6/7) were observed in 7 (87.5%) of 8 pancreatic neuroendocrine carcinomas and 20 (11.76%) of 170 pancreatic ductal adenocarcinomas (PDACs). We tested FAK variants in 157 tumor samples collected from Chinese patients with pancreatic tumors, and found that FAK6/7 was positive in 34 (75.6%) of 45 pancreatic NENs, 19 (47.5%) of 40 pancreatic solid pseudopapillary neoplasms, and 2 (2.9%) of 69 PDACs. We further tested FAK splicing variants in breast neuroendocrine carcinoma (BrNECs), and found that FAK6/7 was positive in 14 (93.3%) of 15 BrNECs but 0 in 23 non-NEC breast cancers. We explored the underlying mechanisms and found that a splicing factor serine/arginine repetitive matrix protein 4 (SRRM4) was overexpressed in FAK6/7-positive pancreatic tumors and breast tumors, which promoted the formation of FAK6/7 in cells. These results suggested that FAK6/7 could be a biomarker of NENs and represent a potential therapeutic target for these orphan diseases.
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Affiliation(s)
- Dawei Xie
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Zheng Wang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Beibei Sun
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Liwei Qu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences & University of Chinese Academy of Sciences, Beijing, 100101, China
| | - Musheng Zeng
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Lin Feng
- Department of Gastroenterology & Hepatology and Department of Pathology, Chinese People's Liberation Army General Hospital, Beijing, 100853, China
| | - Mingzhou Guo
- Department of Gastroenterology & Hepatology and Department of Pathology, Chinese People's Liberation Army General Hospital, Beijing, 100853, China.
| | - Guizhen Wang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
| | - Jihui Hao
- Department of Pancreatic Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin, 300060, China.
| | - Guangbiao Zhou
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
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Sznajder L, Khan M, Tadross M, Ciesiołka A, Nutter C, Taylor K, Pearson C, Sobczak K, Lewis M, Swanson M, Yuen R. Autistic traits in myotonic dystrophy type 1 due to MBNL inhibition and RNA mis-splicing. Res Sq 2023:rs.3.rs-3221704. [PMID: 37645891 PMCID: PMC10462192 DOI: 10.21203/rs.3.rs-3221704/v1] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Tandem repeat expansions are enriched in autism spectrum disorder, including CTG expansion in the DMPK gene that underlines myotonic muscular dystrophy type 1. Although the clinical connection of autism to myotonic dystrophy is corroborated, the molecular links remained unknown. Here, we show a mechanistic path of autism via repeat expansion in myotonic dystrophy. We found that inhibition of muscleblind-like (MBNL) splicing factors by expanded CUG RNAs alerts the splicing of autism-risk genes during brain development especially a class of autism-relevant microexons. To provide in vivo evidence that the CTG expansion and MBNL inhibition axis leads to the presentation of autistic traits, we demonstrate that CTG expansion and MBNL-null mouse models recapitulate autism-relevant mis-splicing profiles and demonstrate social deficits. Our findings indicate that DMPK CTG expansion-associated autism arises from developmental mis-splicing. Understanding this pathomechanistic connection provides an opportunity for greater in-depth investigations of mechanistic threads in autism.
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Yoshida M, Oda C, Mishima K, Tsuji I, Obika S, Shimojo M. An antisense amido-bridged nucleic acid gapmer oligonucleotide targeting SRRM4 alters REST splicing and exhibits anti-tumor effects in small cell lung cancer and prostate cancer cells. Cancer Cell Int 2023; 23:8. [PMID: 36650528 PMCID: PMC9847160 DOI: 10.1186/s12935-022-02842-1] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 12/27/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Antisense oligonucleotide (ASO) medicine for clinical applications has been becoming a reality. We previously developed a gapmer ASO targeting Ser/Arg repetitive matrix 4 (SRRM4) that is abnormally expressed in small cell lung cancer (SCLC). However the detailed mechanism of ASO through repressing SRRM4 has not been completely elucidated. Further, effectiveness of SRRM4 ASO to prostate cancer (PCa) cells expressing SRRM4 similar to SCLC remains to be elucidated. RE1-silencing transcription factor (REST) is a tumor suppressor, and its splicing isoform (sREST) is abnormally expressed by SRRM4 and causes carcinogenesis with neuroendocrine phenotype in SCLC. The present study aimed to understand the contribution of REST splicing by SRRM4 ASO administration. METHODS SRRM4 expression and REST splicing were analyzed by RT-qPCR and conventional RT-PCR after treating SRRM4 ASO, and cell viability was analyzed in vitro. Exogenous reconstitution of Flag-tagged REST plasmid in SCLC cells and the splice-switching oligonucleotide (SSO) specific for REST was analyzed for cell viability. Furthermore, we expanded the application of SRRM4 ASO in PCa cells abnormally expressing SRRM4 mRNA in vitro. RESULTS SRRM4 ASO successfully downregulated SRRM4 expression, followed by repressed cell viability of SCLC and PCa cells in a dose-dependent manner. Administration of SRRM4 ASO then modified the alternative splicing of REST, resulting reduced cell viability. REST SSO specifically modified REST splicing increased REST expression, resulting in reduced cell viability. CONCLUSIONS Our data demonstrate that a gapmer ASO targeting SRRM4 (SRRM4 ASO) reduces cell viability through splicing changes of REST, followed by affecting REST-controlled genes in recalcitrant tumors SCLC and PCa cells.
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Affiliation(s)
- Misa Yoshida
- grid.136593.b0000 0004 0373 3971Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan
| | - Chihiro Oda
- grid.136593.b0000 0004 0373 3971School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan
| | - Keishiro Mishima
- grid.136593.b0000 0004 0373 3971Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan
| | - Itsuki Tsuji
- grid.136593.b0000 0004 0373 3971Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan
| | - Satoshi Obika
- grid.136593.b0000 0004 0373 3971Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan ,grid.136593.b0000 0004 0373 3971School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan ,grid.136593.b0000 0004 0373 3971Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Osaka, 565-0871 Japan ,grid.482562.fNational Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Ibaraki, Osaka 567-0085 Japan
| | - Masahito Shimojo
- grid.136593.b0000 0004 0373 3971Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871 Japan
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Conn VM, Gabryelska M, Marri S, Stringer BW, Ormsby RJ, Penn T, Poonnoose S, Kichenadasse G, Conn SJ. SRRM4 Expands the Repertoire of Circular RNAs by Regulating Microexon Inclusion. Cells 2020; 9:E2488. [PMID: 33207694 DOI: 10.3390/cells9112488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/27/2020] [Accepted: 11/13/2020] [Indexed: 12/25/2022] Open
Abstract
High-throughput RNA sequencing (RNA-seq) and dedicated bioinformatics pipelines have synergized to identify an expansive repertoire of unique circular RNAs (circRNAs), exceeding 100,000 variants. While the vast majority of these circRNAs comprise canonical exonic and intronic sequences, microexons (MEs)-which occur in 30% of functional mRNA transcripts-have been entirely overlooked. CircRNAs which contain these known MEs (ME-circRNAs) could be identified with commonly utilized circRNA prediction pipelines, CIRCexplorer2 and CIRI2, but were not previously recognized as ME-circRNAs. In addition, when employing a bespoke bioinformatics pipeline for identifying RNA chimeras, called Hyb, we could also identify over 2000 ME-circRNAs which contain novel MEs at their backsplice junctions, that are uncalled by either CIRCexplorer2 or CIRI2. Analysis of circRNA-seq datasets from gliomas of varying clinical grades compared with matched control tissue has shown circRNAs have potential as prognostic markers for stratifying tumor from healthy tissue. Furthermore, the abundance of microexon-containing circRNAs (ME-circRNAs) between tumor and normal tissues is correlated with the expression of a splicing associated factor, Serine/arginine repetitive matrix 4 (SRRM4). Overexpressing SRRM4, known for regulating ME inclusion in mRNAs critical for neural differentiation, in human HEK293 cells resulted in the biogenesis of over 2000 novel ME-circRNAs, including ME-circEIF4G3, and changes in the abundance of many canonical circRNAs, including circSETDB2 and circLBRA. This shows SRRM4, in which its expression is correlated with poor prognosis in gliomas, acts as a bona fide circRNA biogenesis factor. Given the known roles of MEs and circRNAs in oncogenesis, the identification of these previously unrecognized ME-circRNAs further increases the complexity and functional purview of this non-coding RNA family.
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Coleman DJ, Sampson DA, Sehrawat A, Kumaraswamy A, Sun D, Wang Y, Schwartzman J, Urrutia J, Lee AR, Coleman IM, Nelson PS, Dong X, Morrissey C, Corey E, Xia Z, Yates JA, Alumkal JJ. Alternative splicing of LSD1+8a in neuroendocrine prostate cancer is mediated by SRRM4. Neoplasia 2020; 22:253-262. [PMID: 32403054 PMCID: PMC7218227 DOI: 10.1016/j.neo.2020.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 04/06/2020] [Indexed: 02/06/2023] Open
Abstract
Neuroendocrine prostate cancer (NEPC) is the most virulent form of prostate cancer. Importantly, our recent work examining metastatic biopsy samples demonstrates NEPC is increasing in frequency. In contrast to prostate adenocarcinomas that express a luminal gene expression program, NEPC tumors express a neuronal gene expression program. Despite this distinction, the diagnosis of NEPC is often challenging, demonstrating an urgent need to identify new biomarkers and therapeutic targets. Our prior work demonstrated that the histone demethylase LSD1 (KDM1A) is important for survival of prostate adenocarcinomas, but little was known about LSD1's role in NEPC. Recently, a neural-specific transcript variant of LSD1-LSD1+8a-was discovered and demonstrated to activate neuronal gene expression in neural cells. The splicing factor SRRM4 was previously shown to promote LSD1+8a splicing in neuronal cells, and SRRM4 promotes NEPC differentiation and cell survival. Therefore, we sought to determine if LSD1+8a might play a role in NEPC and whether LSD1+8a splicing was linked to SRRM4. To investigate a potential role for LSD1+8a in NEPC, we examined a panel of prostate adenocarcinoma and NEPC patient-derived xenografts and metastatic biopsies. LSD1+8a was expressed exclusively in NEPC samples and correlated significantly with elevated expression of SRRM4. Using SRRM4-overexpressing cell lines, we determined that SRRM4 mediates alternative splicing of LSD1+8a. Finally, using gain of function studies, we confirmed that LSD1+8a and SRRM4 co-regulate target genes distinct from canonical LSD1. Our findings suggest further study of the interplay between SRRM4 and LSD1+8a and mechanisms by which LSD1+8a regulates gene expression in NEPC is warranted.
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Affiliation(s)
- Daniel J Coleman
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - David A Sampson
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Archana Sehrawat
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Anbarasu Kumaraswamy
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA
| | - Duanchen Sun
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA; Computational Biology Program, Oregon Health & Science University, Portland, OR, USA
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Jacob Schwartzman
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Joshua Urrutia
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Ahn R Lee
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Ilsa M Coleman
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Peter S Nelson
- Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Colm Morrissey
- Department of Urology, University of Washington, Seattle, WA, USA
| | - Eva Corey
- Department of Urology, University of Washington, Seattle, WA, USA
| | - Zheng Xia
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA; Computational Biology Program, Oregon Health & Science University, Portland, OR, USA
| | - Joel A Yates
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA
| | - Joshi J Alumkal
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA; Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA.
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Nakano Y, Wiechert S, Bánfi B. Overlapping Activities of Two Neuronal Splicing Factors Switch the GABA Effect from Excitatory to Inhibitory by Regulating REST. Cell Rep 2019; 27:860-871.e8. [PMID: 30995482 PMCID: PMC6556397 DOI: 10.1016/j.celrep.2019.03.072] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [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: 08/10/2015] [Revised: 01/22/2019] [Accepted: 03/18/2019] [Indexed: 11/23/2022] Open
Abstract
A truncating mutation in the mouse Srrm4 gene, which encodes a neuronal splicing factor, causes alternative splicing defects selectively in the ear. The mechanism by which splicing is preserved in the brain of these mice is not known. Here, we show that SRRM3 limits the Srrm4 mutation-associated defects to the ear and that, in cortical neurons, overlapping SRRM3-SRRM4 activity regulates the development of interneuronal inhibition. In vitro, SRRM3 and SRRM4 regulate the same splicing events, but a mutation in mouse Srrm3 causes tremors and mild defects in neuronal alternative splicing, demonstrating unique SRRM3 roles in vivo. Mice harboring mutations in both Srrm3 and Srrm4 die neonatally and exhibit severe splicing defects. In these mice, splicing alterations prevent inactivation of the gene repressor REST, which maintains immature excitatory GABAergic neurotransmission by repressing K-Cl cotransporter 2. Thus, our data reveal that SRRM3 and SRRM4 act redundantly to regulate GABAergic neurotransmission by inactivating REST.
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Affiliation(s)
- Yoko Nakano
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Inflammation Program, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Susan Wiechert
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Inflammation Program, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Botond Bánfi
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Inflammation Program, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Otolaryngology-Head and Neck Surgery, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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Li Y, Xie N, Chen R, Lee AR, Lovnicki J, Morrison EA, Fazli L, Zhang Q, Musselman CA, Wang Y, Huang J, Gleave ME, Collins C, Dong X. RNA Splicing of the BHC80 Gene Contributes to Neuroendocrine Prostate Cancer Progression. Eur Urol 2019; 76:157-166. [PMID: 30910347 DOI: 10.1016/j.eururo.2019.03.011] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 03/08/2019] [Indexed: 02/01/2023]
Abstract
BACKGROUND Prostate adenocarcinoma (AdPC) progression to treatment-induced neuroendocrine prostate cancer (t-NEPC) is associated with poor patient survival. While AdPC and t-NEPC share similar genomes, they possess distinct transcriptomes, suggesting that RNA splicing and epigenetic mechanisms may regulate t-NEPC development. OBJECTIVE To characterize the role of alternative RNA splicing of the histone demethylase BHC80 during t-NEPC progression. DESIGN, SETTING, AND PARTICIPANTS The expression of BHC80 splice variants (BHC80-1 and BHC80-2) were compared between AdPC and t-NEPC patient tumors. Regulatory mechanisms of RNA splicing of the BHC80 gene were studied, and the signal pathways mediated by BHC80 splice variants were investigated in t-NEPC cell and xenograft models. RESULTS Global transcriptome analyses identified that the BHC80-2 variant is highly expressed in t-NEPC. Compared with the known histone demethylation activities of the BHC80 gene, we discovered a novel nonepigenetic action of BHC80-2, whereby BHC80-2 is localized in the cytoplasm to trigger the MyD88-p38-TTP pathway, which results in increased RNA stability of multiple tumor-promoting cytokines. While BHC80-2 does not induce neuroendocrine differentiation of cancer cells, it stimulates cell proliferation and tumor progression independent of androgen receptor signaling. Blockade of BHC80-2-regulated MyD88 signaling suppresses growth of several t-NEPC cell spheroid and xenograft models. CONCLUSIONS Gain of function of BHC80-2 through alternative RNA splicing activates immune responses of cancer cells to promote t-NEPC development. PATIENT SUMMARY The main obstacle to develop effective therapies for patients with t-NEPC is the lack of understanding on how t-NEPC is developed. Our study not only identifies a previously unknown BHC80-2-MyD88 signaling pathway that plays an important role during t-NEPC development, but also provides a proof of principle that targeting this signal pathway may offer an avenue to treat t-NEPC.
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Affiliation(s)
- Yinan Li
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ning Xie
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ruiqi Chen
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ahn R Lee
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Jessica Lovnicki
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Emma A Morrison
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Ladan Fazli
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Qingfu Zhang
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA; China Medical University, Shenyang, China
| | - Catherine A Musselman
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Jiaoti Huang
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA
| | - Martin E Gleave
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Colin Collins
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada.
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Li Y, Zhang Q, Lovnicki J, Chen R, Fazli L, Wang Y, Gleave M, Huang J, Dong X. SRRM4 gene expression correlates with neuroendocrine prostate cancer. Prostate 2019; 79:96-104. [PMID: 30155992 DOI: 10.1002/pros.23715] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/14/2018] [Indexed: 12/29/2022]
Abstract
Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of castrate-resistant prostate cancer characterized by poor patient outcome. Whole transcriptome sequencing analyses identified a NEPC-specific RNA splicing program that is predominantly controlled by the SRRM4 gene, suggesting that SRRM4 drives NEPC development. However, whether SRRM4 expression in patients may aid pathologists in diagnosing NEPC and predicting patient survival remains to be determined. In this study, we have applied RNA in situ hybridization and immunohistochemistry assays to measure the expressions of SRRM4, NEPC markers (SYP, CD56, and CHGA), and adenocarcinoma (AdPC) markers (AR, PSA) in a series of tissue microarrays constructed from castrate-resistant prostate tumors, treatment-naïve tumors collected from radical prostatectomy, and tumors treated with neoadjuvant hormonal therapy (NHT) for 0-12 months. Three pathologists also independently evaluated tumor histology and NEPC marker status. Here, we report that SRRM4 in castrate-resistant tumors is highly expressed in NEPC, strongly correlated with SYP, CD56, and CHGA expressions (Pearson correlation r = 0.883, 0.675, and 0.881; P < 0.0001) and negatively correlated with AR and PSA expressions (Pearson correlation r = -0.544 and -0.310; P < 0.05). Overall survival is 12.3 months for patients with SRRM4 positive tumors, comparing to 23 months for patients with SRRM4 negative tumors. In treatment-naïve AdPC, low SRRM4 expression is detected in ∼16% tumor cores. It correlates with SYP and CHGA expressions, but not Gleason scores. AdPC treated with >7 month NHT has significantly higher SRRM4 expression. Based on these findings, we conclude that SRRM4 expression in castrate-resistant tumors is highly correlated with NEPC and poor patient survival. It may serve as a diagnosis and prognosis biomarker of NEPC.
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Affiliation(s)
- Yinan Li
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Qingfu Zhang
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
- China Medical University, Shenyang, China
| | - Jessica Lovnicki
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ruiqi Chen
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ladan Fazli
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yuzhuo Wang
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Martin Gleave
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jiaoti Huang
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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10
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Lee AR, Gan Y, Xie N, Ramnarine VR, Lovnicki JM, Dong X. Alternative RNA splicing of the GIT1 gene is associated with neuroendocrine prostate cancer. Cancer Sci 2018; 110:245-255. [PMID: 30417466 PMCID: PMC6317919 DOI: 10.1111/cas.13869] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/29/2018] [Accepted: 11/05/2018] [Indexed: 12/23/2022] Open
Abstract
Potent androgen receptor pathway inhibition (ARPI) therapies have given rise to a lethal, aggressive subtype of castration‐resistant prostate cancer (CRPC) called treatment‐induced neuroendocrine prostate cancer (t‐NEPC). Now, t‐NEPC poses a major clinical problem as approximately 20% of CRPC cases bear this subtype—a rate of occurrence that is predicted to rise with the widespread use of ARPI therapies. Unfortunately, there are no targeted therapies currently available to treat t‐NEPC as the origin and molecular underpinnings of t‐NEPC development remain unclear. In the present study, we identify that RNA splicing of the G protein‐coupled receptor kinase‐interacting protein 1 (GIT1) gene is a unique event in t‐NEPC patients. Specifically, upregulation of the GIT1‐A splice variant and downregulation of the GIT1‐C variant expressions are associated with t‐NEPC patient tumors, patient‐derived xenografts, and cell models. RNA‐binding assays show that RNA splicing of GIT1 is directly driven by SRRM4 and is associated with the neuroendocrine phenotype in CRPC cohorts. We show that GIT1‐A and GIT1‐C regulate differential transcriptomes in prostate cancer cells, where GIT1‐A regulates genes associated with morphogenesis, neural function, environmental sensing via cell‐adhesion processes, and epigenetic regulation. Consistent with our transcriptomic analyses, we report opposing functions of GIT1‐A and GIT1‐C in the stability of focal adhesions, whereby GIT1‐A promotes focal adhesion stability. In summary, our study is the first to report that alternative RNA splicing of the GIT1 gene is associated with t‐NEPC and reprograms its function involving FA‐mediated signaling and cell processes, which may contribute to t‐NEPC development.
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Affiliation(s)
- Ahn R Lee
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Yu Gan
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada.,Department of Urology, Xiangya Hospital, Central South University, Changsha, China
| | - Ning Xie
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Varune R Ramnarine
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Jessica M Lovnicki
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada
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11
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Lee AR, Gan Y, Tang Y, Dong X. A novel mechanism of SRRM4 in promoting neuroendocrine prostate cancer development via a pluripotency gene network. EBioMedicine 2018; 35:167-177. [PMID: 30100395 PMCID: PMC6154886 DOI: 10.1016/j.ebiom.2018.08.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 08/03/2018] [Accepted: 08/06/2018] [Indexed: 12/26/2022] Open
Abstract
Background Prostate adenocarcinoma (AdPC) cells can undergo lineage switching to neuroendocrine cells and develop into therapy-resistant neuroendocrine prostate cancer (NEPC). While genomic/epigenetic alterations are shown to induce neuroendocrine differentiation via an intermediate stem-like state, RNA splicing factor SRRM4 can transform AdPC cells into NEPC xenografts through a direct neuroendocrine transdifferentiation mechanism. Whether SRRM4 can also regulate a stem-cell gene network for NEPC development remains unclear. Methods Multiple AdPC cell models were transduced by lentiviral vectors encoding SRRM4. SRRM4-mediated RNA splicing and neuroendocrine differentiation of cells and xenografts were determined by qPCR, immunoblotting, and immunohistochemistry. Cell morphology, proliferation, and colony formation rates were also studied. SRRM4 transcriptome in the DU145 cell model was profiled by AmpliSeq and analyzed by gene enrichment studies. Findings SRRM4 induces an overall NEPC-specific RNA splicing program in multiple cell models but creates heterogeneous transcriptomes. SRRM4-transduced DU145 cells present the most dramatic neuronal morphological changes, accelerated cell proliferation, and enhanced resistance to apoptosis. The derived xenografts show classic phenotypes similar to clinical NEPC. Whole transcriptome analyses further reveal that SRRM4 induces a pluripotency gene network consisting of the stem-cell differentiation gene, SOX2. While SRRM4 overexpression enhances SOX2 expression in both time- and dose-dependent manners in DU145 cells, RNA depletion of SOX2 compromises SRRM4-mediated stimulation of pluripotency genes. More importantly, this SRRM4-SOX2 axis is present in a subset of NEPC patient cohorts, patient-derived xenografts, and clinically relevant transgenic mouse models. Interpretation We report a novel mechanism by which SRRM4 drives NEPC progression via a pluripotency gene network. Fund Canadian Institutes of Health Research, National Nature Science Foundation of China, and China Scholar Council.
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Affiliation(s)
- Ahn R Lee
- Vancouver Prostate Centre, Department of Urologic Sciences, The University of British Columbia, 2660 Oak Street, Vancouver, BC, Canada.
| | - Yu Gan
- Vancouver Prostate Centre, Department of Urologic Sciences, The University of British Columbia, 2660 Oak Street, Vancouver, BC, Canada; Xiangya Hospital, Department of Urology, Central South University, Changsha, Hunan, China; Third Xiangya Hospital, Department of Urology, Central South University, Changsha, Hunan, China.
| | - Yuxin Tang
- Third Xiangya Hospital, Department of Urology, Central South University, Changsha, Hunan, China.
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, The University of British Columbia, 2660 Oak Street, Vancouver, BC, Canada.
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12
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Gan Y, Li Y, Long Z, Lee AR, Xie N, Lovnicki JM, Tang Y, Chen X, Huang J, Dong X. Roles of Alternative RNA Splicing of the Bif-1 Gene by SRRM4 During the Development of Treatment-induced Neuroendocrine Prostate Cancer. EBioMedicine 2018; 31:267-275. [PMID: 29759485 PMCID: PMC6013970 DOI: 10.1016/j.ebiom.2018.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/12/2018] [Accepted: 05/01/2018] [Indexed: 02/02/2023] Open
Abstract
Treatment-induced neuroendocrine prostate cancer (t-NEPC) is an aggressive subtype of prostate cancer (PCa) that becomes more prevalent when hormonal therapy, chemotherapy, or radiation therapy is applied to patients with metastatic prostate adenocarcinoma (AdPC). How AdPC cells survive these anti-cancer therapies and progress into t-NEPC remains unclear. By comparing the whole transcriptomes between AdPC and t-NEPC, we identified Bif-1, an apoptosis-associated gene, which undergoes alternative RNA splicing in t-NEPC. We found that while Bif-1a is the predominant variant of the Bif-1 gene in AdPC, two neural-specific variants, Bif-1b and Bif-1c, are highly expressed in t-NEPC patients, patient derived xenografts, and cell models. The neural-specific RNA splicing factor, SRRM4, promotes Bif-1b and Bif-1c splicing, and the expression of SRRM4 in tumors is strongly associated with Bif-1b/-1c levels. Furthermore, we showed that Bif-1a is pro-apoptotic, while Bif-1b and Bif-1c are anti-apoptotic in PCa cells under camptothecin and UV light irritation treatments. Taken together, our data indicate that SRRM4 regulates alternative RNA splicing of the Bif-1 gene that enables PCa cells resistant to apoptotic stimuli under anti-cancer therapies, and may contribute to AdPC progression into t-NEPC. Alternative RNA splicing of the apoptosis-related gene, Bif-1, is associated with the development of t-NEPC. SRRM4 regulates alternative RNA splicing of the Bif-1 gene. Bif-1a in AdPC cells is pro-apoptotic, while neural Bif-1 variants, Bif-1b/-1c, enable tumor cells resistant to apoptosis.
Treatment-induced neuroendocrine prostate cancer (t-NEPC) is an aggressive subtype of castration-resistant prostate cancer. It becomes more prevalent when more potent androgen receptor inhibitors are applied to patients. However, mechanisms by which t-NEPC develops remain unclear. Here we report alternative RNA splicing of the apoptosis-related gene, Bif-1, may contribute to t-NEPC establishment. We show that the expression of neural Bif-1 variants is upregulated in t-NEPC, and confers tumor cells resistance to apoptotic stimuli. We propose that tumor cells have to first develop mechanisms to counteract therapy-induced cell death before they can undergo neuroendocrine differentiation for t-NEPC.
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Affiliation(s)
- Yu Gan
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada; Department of Urology, Xiangya Hospital, Central South University, Changsha, China; Department of Urology, Third Xiangya Hospital, Central South University, Changsha, China.
| | - Yinan Li
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada.
| | - Zhi Long
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada; Department of Urology, Third Xiangya Hospital, Central South University, Changsha, China.
| | - Ahn R Lee
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada.
| | - Ning Xie
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada.
| | - Jessica M Lovnicki
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada.
| | - Yuxin Tang
- Department of Urology, Third Xiangya Hospital, Central South University, Changsha, China.
| | - Xiang Chen
- Department of Urology, Xiangya Hospital, Central South University, Changsha, China.
| | - Jiaoti Huang
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA.
| | - Xuesen Dong
- Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Canada.
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13
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Li Y, Chen R, Bowden M, Mo F, Lin YY, Gleave M, Collins C, Dong X. Establishment of a neuroendocrine prostate cancer model driven by the RNA splicing factor SRRM4. Oncotarget 2017; 8:66878-66888. [PMID: 28978002 PMCID: PMC5620142 DOI: 10.18632/oncotarget.19916] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/06/2017] [Indexed: 12/20/2022] Open
Abstract
Neuroendocrine prostate cancer (NEPC) is becoming more prevalent as more potent androgen receptor (AR) pathway inhibitors are applied to patients with metastatic tumors. However, there are limited cell and xenograft models currently available, hindering the investigation of signal pathways involved in regulating NEPC progression and the design of high throughput screening assays for inhibitors to treat NEPC patients. Here, we report an NEPC model, LnNE, that is derived from prostate adenocarcinoma cells and has global similarity in transcription and RNA splicing to tumors from NEPC patients. LnNE xenografts are castrate-resistant and highly aggressive. Its tumor take is ∼3-5 weeks and tumor doubling time is ∼2-3 weeks. LnNE expresses multiple neuroendocrine markers, preserves AR expression, but is PSA negative. Its neuroendocrine phenotype cannot be reversed by androgen treatment. LnNE cells grow as multi-cellular spheroids under 2-dimensional culture conditions similar to the NEPC cell line NCI-H660, but have higher proliferation rate and are easier to be transfected. LnNE cells can also adapt to 3-dimensional culture conditions in a 96-plate format, allowing high throughput screening assays. In summary, the LnNE model is useful to study the mechanisms of NEPC progression and to discover potential therapies for NEPC.
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Affiliation(s)
- Yinan Li
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Ruiqi Chen
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Mary Bowden
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Fan Mo
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Yen-Yi Lin
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Martin Gleave
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Colin Collins
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
| | - Xuesen Dong
- Department of Urologic Sciences, Vancouver Prostate Centre, The University of British Columbia, Vancouver, Canada
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14
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Li Y, Donmez N, Sahinalp C, Xie N, Wang Y, Xue H, Mo F, Beltran H, Gleave M, Wang Y, Collins C, Dong X. SRRM4 Drives Neuroendocrine Transdifferentiation of Prostate Adenocarcinoma Under Androgen Receptor Pathway Inhibition. Eur Urol 2017; 71:68-78. [PMID: 27180064 DOI: 10.1016/j.eururo.2016.04.028] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/20/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of castration-resistant prostate cancer that typically does not respond to androgen receptor pathway inhibition (ARPI), and its diagnosis is increasing. OBJECTIVE To understand how NEPC develops and to identify driver genes to inform therapy for NEPC prevention. DESIGN, SETTING, AND PARTICIPANTS Whole-transcriptome sequencing data were extracted from prostate tumors from two independent cohorts: The Beltran cohort contained 27 adenocarcinoma and five NEPC patient samples, and the Vancouver Prostate Centre cohort contained three patient samples and nine patient-derived xenografts. INTERVENTION A novel bioinformatics tool, comparative alternative splicing detection (COMPAS), was invented to analyze alternative RNA splicing on RNA-sequencing data. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS COMPAS identified potential driver genes for NEPC development. Biochemical and biological validations were performed in both prostate cell and tumor models. RESULTS AND LIMITATION More than 66% of the splice events were predicted to be regulated by the RNA splicing factor serine/arginine repetitive matrix 4 (SRRM4). In vitro and in vivo evidence confirmed that one SRRM4 target gene was the RE1 silencing transcription factor (REST), a master regulator of neurogenesis. Moreover, SRRM4 strongly stimulated adenocarcinoma cells to express NEPC biomarkers, and this effect was exacerbated by ARPI. ARPI combined with a gain of SRRM4-induced adenocarcinoma cells to assume multicellular spheroid morphology and was essential in establishing progressive NEPC xenografts. These SRRM4 actions were further enhanced by loss of function of TP53. CONCLUSIONS SRRM4 drives NEPC progression. This knowledge may guide the development of novel therapeutics aimed at NEPC. PATIENT SUMMARY Using next-generation RNA sequencing and our newly developed bioinformatics tool, we identified a neuroendocrine prostate cancer (NEPC)-specific RNA splicing signature that is predominantly controlled by serine/arginine repetitive matrix 4 (SRRM4). We confirmed that SRRM4 drives NEPC progression, and we propose SRRM4 as a potential therapeutic target for NEPC.
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