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Mukherjee S, Mukherjee SB, Frenkel-Morgenstern M. Functional and regulatory impact of chimeric RNAs in human normal and cancer cells. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1777. [PMID: 36633099 DOI: 10.1002/wrna.1777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 12/21/2022] [Accepted: 12/27/2022] [Indexed: 01/13/2023]
Abstract
Fusions of two genes can lead to the generation of chimeric RNAs, which may have a distinct functional role from their original molecules. Chimeric RNAs could encode novel functional proteins or serve as novel long noncoding RNAs (lncRNAs). The appearance of chimeric RNAs in a cell could help to generate new functionality and phenotypic diversity that might facilitate this cell to survive against new environmental stress. Several recent studies have demonstrated the functional roles of various chimeric RNAs in cancer progression and are considered as biomarkers for cancer diagnosis and sometimes even drug targets. Further, the growing evidence demonstrated the potential functional association of chimeric RNAs with cancer heterogeneity and drug resistance cancer evolution. Recent studies highlighted that chimeric RNAs also have functional potentiality in normal physiological processes. Several functionally potential chimeric RNAs were discovered in human cancer and normal cells in the last two decades. This could indicate that chimeric RNAs are the hidden layer of the human transcriptome that should be explored from the functional insights to better understand the functional evolution of the genome and disease development that could facilitate clinical practice improvements. This review summarizes the current knowledge of chimeric RNAs and highlights their functional, regulatory, and evolutionary impact on different cancers and normal physiological processes. Further, we will discuss the potential functional roles of a recently discovered novel class of chimeric RNAs named sense-antisense/cross-strand chimeric RNAs generated by the fusion of the bi-directional transcripts of the same gene. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.
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Affiliation(s)
- Sumit Mukherjee
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
- Department of Computer Science, Ben-Gurion University, Beer-Sheva, Israel
- Cancer Data Science Laboratory (CDSL), National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Sunanda Biswas Mukherjee
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Milana Frenkel-Morgenstern
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
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2
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Bakker A, Slack JC, Palanisamy N, Carskadon S, Ghosh S, Khalifeh I, Bismar TA. Loss of KLK4::KLKP1 pseudogene expression by RNA chromogenic in-situ hybridization is associated with PTEN loss and increased risk of biochemical recurrence in a cohort of middle eastern men with prostate cancer. J Cancer Res Clin Oncol 2022:10.1007/s00432-022-04279-5. [PMID: 35982181 DOI: 10.1007/s00432-022-04279-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND KLK4::KLKP1 fusion is a recently described pseudogene that is enriched in prostate cancer (PCa). This new biomarker has not been characterized in the Middle Eastern population. OBJECTIVE To establish the incidence and prognostic value of KLK4::KLKP1 fusion in a cohort of Middle Eastern men with PCa and explore the relationship of this marker to other relevant biomarkers (PTEN, ERG, SPINK1). DESIGN, SETTING, AND PARTICIPANTS We interrogated a cohort of 340 Middle Eastern men with localized PCa treated by radical prostatectomy between 2005 and 2015. KLK4::KLKP1 fusion status was assessed by RNA Chromogenic in situ hybridization (CISH) and correlated to pathological and clinical parameters. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS RNA-CISH expression of KLK4::KLKP1 was correlated with prognostic factors, ERG, PTEN, and SPINK1 expression, and biochemical recurrence (BCR) following prostatectomy. RESULTS AND LIMITATIONS 51.7% of patient samples showed positive KLK4::KLKP1 expression; more commonly in cores of PCa (38%) versus non-cancer (20.6%) (p < 0.0001) and in lower Gleason Grade Group tumors (1-3) vs (4-5). KLK4::KLKP1 expression positively correlated with ERG positivity and inversely associated with PTEN loss. No significant association was found with SPINK1 expression, seminal vesicle invasion, positive surgical margin, pathological stage, or patient age (< 50 or ≥ 50). The association between PTEN loss and BCR increased when combined with KLK4::KLKP1 negativity (HR 2.31, CI 1.03-5.20, p = 0.042). CONCLUSIONS KLK4::KLKP1 expression is more common in this cohort of Middle Eastern men than has been reported in North American men. It is associated with ERG positivity and inversely correlated with PTEN loss. In isolation, KLK4::KLKP1 expression was not significantly associated with clinical outcome or pathological parameters. However, its expression is associated with certain molecular subtypes (ERG-positive, PTEN-intact) and as we demonstrate may help further stratify the risk of recurrence within these groups.
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Affiliation(s)
- Andrea Bakker
- Department of Pathology and Laboratory Medicine, Alberta Precision Laboratories, University of Calgary Cumming School of Medicine, Rockyview General Hospital, Calgary, AB, T2V 1P9, Canada
| | - Jonathan C Slack
- Department of Pathology and Laboratory Medicine, Alberta Precision Laboratories, University of Calgary Cumming School of Medicine, Rockyview General Hospital, Calgary, AB, T2V 1P9, Canada
| | - Nalla Palanisamy
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health System, Detroit, MI, USA
| | - Shannon Carskadon
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health System, Detroit, MI, USA
| | - Sunita Ghosh
- Department of Medical Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Departments of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Ibrahim Khalifeh
- Department of Pathology and Internal Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Tarek A Bismar
- Department of Pathology and Laboratory Medicine, Alberta Precision Laboratories, University of Calgary Cumming School of Medicine, Rockyview General Hospital, Calgary, AB, T2V 1P9, Canada.
- Departments of Oncology, Biochemistry, and Molecular Biology, Calgary, AB, Canada.
- Arnie Charbonneau Cancer Institute and Tom Baker Cancer Center, Calgary, AB, Canada.
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Abrahamsson S, Eiengård F, Rohlin A, Dávila López M. PΨFinder: a practical tool for the identification and visualization of novel pseudogenes in DNA sequencing data. BMC Bioinformatics 2022; 23:59. [PMID: 35114952 PMCID: PMC8812246 DOI: 10.1186/s12859-022-04583-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 01/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Processed pseudogenes (PΨgs) are disabled gene copies that are transcribed and may affect expression of paralogous genes. Moreover, their insertion in the genome can disrupt the structure or the regulatory region of a gene, affecting its expression level. These events have been identified as occurring mutations during cancer development, thus being able to identify PΨgs and their location will improve their impact on diagnostic testing, not only in cancer but also in inherited disorders. RESULTS We have implemented PΨFinder (P-psy-finder), a tool that identifies PΨgs, annotates known ones and predicts their insertion site(s) in the genome. The tool screens alignment files and provides user-friendly summary reports and visualizations. To demonstrate its applicability, we scanned 218 DNA samples from patients screened for hereditary colorectal cancer. We detected 423 PΨgs distributed in 96% of the samples, comprising 7 different parent genes. Among these, we confirmed the well-known insertion site of the SMAD4-PΨg within the last intron of the SCAI gene in one sample. While for the ubiquitous CBX3-PΨg, present in 82.6% of the samples, we found it reversed inserted in the second intron of the C15ORF57 gene. CONCLUSIONS PΨFinder is a tool that can automatically identify novel PΨgs from DNA sequencing data and determine their location in the genome with high sensitivity (95.92%). It generates high quality figures and tables that facilitate the interpretation of the results and can guide the experimental validation. PΨFinder is a complementary analysis to any mutational screening in the identification of disease-causing mutations within cancer and other diseases.
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Affiliation(s)
- Sanna Abrahamsson
- Bioinformatics Core Facility, Sahlgrenska Academy, University of Gothenburg, Box 115, 405 30, Gothenburg, Sweden
| | - Frida Eiengård
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Anna Rohlin
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Unit of Genetic Analysis and Bioinformatics, Department of Clinical Genetics and Genomics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Marcela Dávila López
- Bioinformatics Core Facility, Sahlgrenska Academy, University of Gothenburg, Box 115, 405 30, Gothenburg, Sweden.
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KLK4T2 Is a Hormonally Regulated Transcript from the KLK4 Locus. Int J Mol Sci 2021; 22:ijms222313023. [PMID: 34884832 PMCID: PMC8657796 DOI: 10.3390/ijms222313023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
The human kallikrein-related peptidase 4 (KLK4) and the transcribed pseudogene KLKP1 are reported to be highly expressed in the prostate. When trying to clone transcripts of KLKP1, we partly failed. Instead, we identified an androgen-regulated transcript, KLK4T2, which appeared to be a splice variant of KLK4 that also contained exons of KLKP1. Expression analysis of KLK4, KLK4T2, and KLKP1 transcripts in prostate cancer cell lines showed high levels of KLKP1 transcripts in the nucleus and in unfractionated cell extract, whereas it was almost completely absent in the cytoplasmatic fraction. This was in contrast to KLK4 and KLK4T2, which displayed high to moderate levels in the cytoplasm. In patient cohorts we found significantly higher expression of both KLK4T2 and KLK4 in benign prostatic hyperplasia compared to both primary prostate cancer and bone metastasis. Analysis of tissue panels demonstrated the highest expression of KLK4T2 in the prostate, but in contrast to the classical KLK4, relatively high levels were also found in placenta. So far, the function of KLK4T2 is still to be explored, but the structure of the translation product indicated that it generates a 17.4 kDa intracellular protein with possible regulatory function.
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Troskie RL, Faulkner GJ, Cheetham SW. Processed pseudogenes: A substrate for evolutionary innovation: Retrotransposition contributes to genome evolution by propagating pseudogene sequences with rich regulatory potential throughout the genome. Bioessays 2021; 43:e2100186. [PMID: 34569081 DOI: 10.1002/bies.202100186] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/09/2021] [Accepted: 09/13/2021] [Indexed: 11/08/2022]
Abstract
Processed pseudogenes may serve as a genetic reservoir for evolutionary innovation. Here, we argue that through the activity of long interspersed element-1 retrotransposons, processed pseudogenes disperse coding and noncoding sequences rich with regulatory potential throughout the human genome. While these sequences may appear to be non-functional, a lack of contemporary function does not prohibit future development of biological activity. Here, we discuss the dynamic evolution of certain processed pseudogenes into coding and noncoding genes and regulatory elements, and their implication in wide-ranging biological and pathological processes. Also see the video abstract here: https://youtu.be/iUY_mteVoPI.
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Affiliation(s)
- Robin-Lee Troskie
- Mater Research Institute, University of Queensland, Woolloongabba, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute, University of Queensland, Woolloongabba, Australia.,Queensland Brain Institute, University of Queensland, Brisbane, Australia
| | - Seth W Cheetham
- Mater Research Institute, University of Queensland, Woolloongabba, Australia
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Mukherjee S, Detroja R, Balamurali D, Matveishina E, Medvedeva Y, Valencia A, Gorohovski A, Frenkel-Morgenstern M. Computational analysis of sense-antisense chimeric transcripts reveals their potential regulatory features and the landscape of expression in human cells. NAR Genom Bioinform 2021; 3:lqab074. [PMID: 34458728 PMCID: PMC8386243 DOI: 10.1093/nargab/lqab074] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 07/02/2021] [Accepted: 08/20/2021] [Indexed: 12/11/2022] Open
Abstract
Many human genes are transcribed from both strands and produce sense-antisense gene pairs. Sense-antisense (SAS) chimeric transcripts are produced upon the coalescing of exons/introns from both sense and antisense transcripts of the same gene. SAS chimera was first reported in prostate cancer cells. Subsequently, numerous SAS chimeras have been reported in the ChiTaRS-2.1 database. However, the landscape of their expression in human cells and functional aspects are still unknown. We found that longer palindromic sequences are a unique feature of SAS chimeras. Structural analysis indicates that a long hairpin-like structure formed by many consecutive Watson-Crick base pairs appears because of these long palindromic sequences, which possibly play a similar role as double-stranded RNA (dsRNA), interfering with gene expression. RNA-RNA interaction analysis suggested that SAS chimeras could significantly interact with their parental mRNAs, indicating their potential regulatory features. Here, 267 SAS chimeras were mapped in RNA-seq data from 16 healthy human tissues, revealing their expression in normal cells. Evolutionary analysis suggested the positive selection favoring sense-antisense fusions that significantly impacted the evolution of their function and structure. Overall, our study provides detailed insight into the expression landscape of SAS chimeras in human cells and identifies potential regulatory features.
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Affiliation(s)
- Sumit Mukherjee
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Rajesh Detroja
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Deepak Balamurali
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Elena Matveishina
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russian Federation
- Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow 117312, Russian Federation
| | - Yulia A Medvedeva
- Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow 117312, Russian Federation
- Department of Biomedical Physics, Moscow Institute of Technology, Dolgoprudny 141701, Russian Federation
| | - Alfonso Valencia
- Barcelona Supercomputing Center (BSC), C/ Jordi Girona 29, 08034, Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Alessandro Gorohovski
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Milana Frenkel-Morgenstern
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
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7
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Wang Y, Zou Q, Li F, Zhao W, Xu H, Zhang W, Deng H, Yang X. Identification of the cross-strand chimeric RNAs generated by fusions of bi-directional transcripts. Nat Commun 2021; 12:4645. [PMID: 34330918 PMCID: PMC8324879 DOI: 10.1038/s41467-021-24910-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 07/14/2021] [Indexed: 12/22/2022] Open
Abstract
A major part of the transcriptome complexity is attributed to multiple types of DNA or RNA fusion events, which take place within a gene such as alternative splicing or between different genes such as DNA rearrangement and trans-splicing. In the present study, using the RNA deep sequencing data, we systematically survey a type of non-canonical fusions between the RNA transcripts from the two opposite DNA strands. We name the products of such fusion events cross-strand chimeric RNA (cscRNA). Hundreds to thousands of cscRNAs can be found in human normal tissues, primary cells, and cancerous cells, and in other species as well. Although cscRNAs exhibit strong tissue-specificity, our analysis identifies thousands of recurrent cscRNAs found in multiple different samples. cscRNAs are mostly originated from convergent transcriptions of the annotated genes and their anti-sense DNA. The machinery of cscRNA biogenesis is unclear, but the cross-strand junction events show some features related to RNA splicing. The present study is a comprehensive survey of the non-canonical cross-strand RNA junction events, a resource for further characterization of the originations and functions of the cscRNAs.
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Affiliation(s)
- Yuting Wang
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China.,Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science, Beijing, China
| | - Qin Zou
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Fajin Li
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China.,Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science, Beijing, China
| | - Wenwei Zhao
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hui Xu
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wenhao Zhang
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xuerui Yang
- MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, School of Life Sciences, Tsinghua University, Beijing, China.
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Bok I, Karreth FA. Strategies to Study the Functions of Pseudogenes in Mouse Models of Cancer. Methods Mol Biol 2021; 2324:287-304. [PMID: 34165722 DOI: 10.1007/978-1-0716-1503-4_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Aberrant expression of pseudogenes has been observed in many cancer types. Deregulated pseudogenes engage in a multitude of biological processes at the DNA, RNA, and protein levels and eventually facilitate disease progression. To investigate pseudogene functions in cancer, cell lines and cell line transplantation models have been widely used. However, cancer biology is best studied in the context of an intact organism. Here, we present various strategies to investigate pseudogenes in genetically engineered mouse models and discuss advantages and disadvantages of the different approaches.
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Affiliation(s)
- Ilah Bok
- Cancer Biology Ph.D. Program, University of South Florida, Tampa, FL, USA
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Florian A Karreth
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.
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9
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Vellichirammal NN, Albahrani A, Banwait JK, Mishra NK, Li Y, Roychoudhury S, Kling MJ, Mirza S, Bhakat KK, Band V, Joshi SS, Guda C. Pan-Cancer Analysis Reveals the Diverse Landscape of Novel Sense and Antisense Fusion Transcripts. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 19:1379-1398. [PMID: 32160708 PMCID: PMC7044684 DOI: 10.1016/j.omtn.2020.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 01/03/2020] [Accepted: 01/14/2020] [Indexed: 01/26/2023]
Abstract
Gene fusions that contribute to oncogenicity can be explored for identifying cancer biomarkers and potential drug targets. To investigate the nature and distribution of fusion transcripts in cancer, we examined the transcriptome data of about 9,000 primary tumors from 33 different cancers in TCGA (The Cancer Genome Atlas) along with cell line data from CCLE (Cancer Cell Line Encyclopedia) using ChimeRScope, a novel fusion detection algorithm. We identified several fusions with sense (canonical, 39%) or antisense (non-canonical, 61%) transcripts recurrent across cancers. The majority of the recurrent non-canonical fusions found in our study are novel, unexplored, and exhibited highly variable profiles across cancers, with breast cancer and glioblastoma having the highest and lowest rates, respectively. Overall, 4,344 recurrent fusions were identified from TCGA in this study, of which 70% were novel. Additional analysis of 802 tumor-derived cell line transcriptome data across 20 cancers revealed significant variability in recurrent fusion profiles between primary tumors and corresponding cell lines. A subset of canonical and non-canonical fusions was validated by examining the structural variation evidence in whole-genome sequencing (WGS) data or by Sanger sequencing of fusion junctions. Several recurrent fusion genes identified in our study show promise for drug repurposing in basket trials and present opportunities for mechanistic studies.
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Affiliation(s)
| | - Abrar Albahrani
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jasjit K Banwait
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; Bioinformatics and Systems Biology Core. University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nitish K Mishra
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - You Li
- HitGen, South Keyuan Road 88, Chengdu, China
| | - Shrabasti Roychoudhury
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mathew J Kling
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Sameer Mirza
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kishor K Bhakat
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Vimla Band
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shantaram S Joshi
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; Bioinformatics and Systems Biology Core. University of Nebraska Medical Center, Omaha, NE 68198, USA.
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Abstract
Chimeric RNAs can be formed by trans-splicing from different transcripts or cis-splicing of adjacent genes (cis-SAGe). Cis-SAGe results from read-through transcription of two neighbor genes. To investigate the mechanisms underlying intergenic splicing of adjacent genes, it is important to develop an assay to detect transcriptional read-through. Here, we describe a general RT-PCR based method to confirm the process for cis-SAGe candidates. In this method, we use PCR to amplify cDNA that is reverse transcribed from the read-through precursor mRNA. The result provides a foundation for further downstream mechanistic studies.
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11
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[Virus-host coevolution: Endogenous RNA viral elements as pseudogenes]. Uirusu 2020; 70:49-56. [PMID: 33967113 DOI: 10.2222/jsv.70.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
RNA viruses do not need to take the form of DNAs, and RNAs alone complete their replication cycles. On the other hand, since the 1970s, it has been known that DNA fragments derived from RNA viruses can be detected in RNA virus-infected cells. Furthermore, in this decade, it has become clear that the eukaryotic genomes contain genetic sequences derived from non-retroviral RNA viruses. The DNA sequences derived from these RNA viruses are thought to be generatedby using a transposable mechanism of retrotransposon, such as LINE-1. Many endogenous RNA viral sequences are formed by the same mechanism as processed pseudogenes in eukaryotic cells, but the significance of the production of RNA viral "pseudogenes " in infected cells has not been elucidated. We have discovered endogenous bornavirus-like elements (EBLs), which derived from a negative-sense, single-stranded RNA virus, Bornaviruses, and have studied the evolution and function of EBLs in host animals. The analysis of EBLs provides us a clue to unravel the history of host-RNA virus coexistence. In this review, I overview about the function of endogenous RNA virus sequences, especially EBLs in mammalian genomes, and discuss the significance of endogenization of RNA viruses as viral pseudogenes in evolution.
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12
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Overcoming challenges and dogmas to understand the functions of pseudogenes. Nat Rev Genet 2019; 21:191-201. [DOI: 10.1038/s41576-019-0196-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2019] [Indexed: 01/08/2023]
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13
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Rose AM, Krishan A, Chakarova CF, Moya L, Chambers SK, Hollands M, Illingworth JC, Williams SMG, McCabe HE, Shah AZ, Palmer CNA, Chakravarti A, Berg JN, Batra J, Bhattacharya SS. MSR1 repeats modulate gene expression and affect risk of breast and prostate cancer. Ann Oncol 2019; 29:1292-1303. [PMID: 29509840 DOI: 10.1093/annonc/mdy082] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background MSR1 repeats are a 36-38 bp minisatellite element that have recently been implicated in the regulation of gene expression, through copy number variation (CNV). Patients and methods Bioinformatic and experimental methods were used to assess the distribution of MSR1 across the genome, evaluate the regulatory potential of such elements and explore the role of MSR1 elements in cancer, particularly non-familial breast cancer and prostate cancer. Results MSR1s are predominately located at chromosome 19 and are functionally enriched in regulatory regions of the genome, particularly regions implicated in short-range regulatory activities (H3K27ac, H3K4me1 and H3K4me3). MSR1-regulated genes were found to have specific molecular roles, such as serine-protease activity (P = 4.80 × 10-7) and ion channel activity (P = 2.7 × 10-4). The kallikrein locus was found to contain a large number of MSR1 clusters, and at least six of these showed CNV. An MSR1 cluster was identified within KLK14, with 9 and 11 copies being normal variants. A significant association with the 9-copy allele and non-familial breast cancer was found in two independent populations (P = 0.004; P = 0.03). In the white British population, the minor allele conferred an increased risk of 1.21-3.51 times for all non-familial disease, or 1.7-5.3 times in early-onset disease. The 9-copy allele was also found to be associated with increased risk of prostate cancer in an independent population (odds ratio = 1.27-1.56; P =0.009). Conclusions MSR1 repeats act as molecular switches that modulate gene expression. It is likely that CNV of MSR1 will affect risk of development of various forms of cancer, including that of breast and prostate. The MSR1 cluster at KLK14 represents the strongest risk factor identified to date in non-familial breast cancer and a significant risk factor for prostate cancer. Analysis of MSR1 genotype will allow development of precise stratification of disease risk and provide a novel target for therapeutic agents.
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Affiliation(s)
- A M Rose
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK.
| | - A Krishan
- Cell Therapy and Regenerative Medicine, CABIMER, Seville, Spain
| | - C F Chakarova
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK
| | - L Moya
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane; Cancer Program, School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane
| | - S K Chambers
- Menzies Health Institute Queensland, Griffith University, Southport; Cancer Research Centre, Cancer Council Queensland, Brisbane, Australia
| | - M Hollands
- UCL Medical School, University College London, London
| | | | | | - H E McCabe
- Clinical Genetics, Ninewells Hospital & Medical School, University of Dundee, Dundee
| | - A Z Shah
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK
| | - C N A Palmer
- Centre for Pharmacogenetics and Pharmacogenomics, Ninewells Hospital and School of Medicine, University of Dundee, Dundee, UK
| | - A Chakravarti
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, USA
| | - J N Berg
- Clinical Genetics, Ninewells Hospital & Medical School, University of Dundee, Dundee
| | - J Batra
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane; Cancer Program, School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane
| | - S S Bhattacharya
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK; Cell Therapy and Regenerative Medicine, CABIMER, Seville, Spain
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Pseudogene Associated Recurrent Gene Fusion in Prostate Cancer. Neoplasia 2019; 21:989-1002. [PMID: 31446281 PMCID: PMC6713813 DOI: 10.1016/j.neo.2019.07.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 02/08/2023] Open
Abstract
We present the functional characterization of a pseudogene associated recurrent gene fusion in prostate cancer. The fusion gene KLK4-KLKP1 is formed by the fusion of the protein coding gene KLK4 with the noncoding pseudogene KLKP1. Screening of a cohort of 659 patients (380 Caucasian American; 250 African American, and 29 patients from other races) revealed that the KLK4-KLKP1 is expressed in about 32% of prostate cancer patients. Correlative analysis with other ETS gene fusions and SPINK1 revealed a concomitant expression pattern of KLK4-KLKP1 with ERG and a mutually exclusive expression pattern with SPINK1, ETV1, ETV4, and ETV5. Development of an antibody specific to KLK4-KLKP1 fusion protein confirmed the expression of the full-length KLK4-KLKP1 protein in prostate tissues. The in vitro and in vivo functional assays to study the oncogenic properties of KLK4-KLKP1 confirmed its role in cell proliferation, cell invasion, intravasation, and tumor formation. Presence of strong ERG and AR binding sites located at the fusion junction in KLK4-KLKP1 suggests that the fusion gene is regulated by ERG and AR. Correlative analysis of clinical data showed an association of KLK4-KLKP1 with lower preoperative PSA values and in young men (<50 years) with prostate cancer. Screening of patient urine samples showed that KLK4-KLKP1 can be detected noninvasively in urine. Taken together, we present KLK4-KLKP1 as a class of pseudogene associated fusion transcript in cancer with potential applications as a biomarker for routine screening of prostate cancer.
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Current Transport Systems and Clinical Applications for Small Interfering RNA (siRNA) Drugs. Mol Diagn Ther 2019; 22:551-569. [PMID: 29926308 DOI: 10.1007/s40291-018-0338-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Small interfering RNAs (siRNAs) are an attractive new agent with potential as a therapeutic tool because of its ability to inhibit specific genes for many conditions, including viral infections and cancers. However, despite this potential, many challenges remain, including off-target effects, difficulties with delivery, immune responses, and toxicity. Traditional genetic vectors do not guarantee that siRNAs will silence genes in vivo. Rational design strategies, such as chemical modification, viral vectors, and non-viral vectors, including cationic liposomes, polymers, nanocarriers, and bioconjugated siRNAs, provide important opportunities to overcome these challenges. We summarize the results of research into vector delivery of siRNAs as a therapeutic agent from their design to clinical trials in ophthalmic diseases, cancers, respiratory diseases, and liver virus infections. Finally, we discuss the current state of siRNA delivery methods and the need for greater understanding of the requirements.
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Interfering Expression of Chimeric Transcript SEPT7P2-PSPH Promotes Cell Proliferation in Patients with Nasopharyngeal Carcinoma. JOURNAL OF ONCOLOGY 2019; 2019:1654724. [PMID: 31057610 PMCID: PMC6463592 DOI: 10.1155/2019/1654724] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 01/09/2019] [Accepted: 02/03/2019] [Indexed: 01/09/2023]
Abstract
Introduction Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer which is mostly prevalent in southern China. The development of NPC involves accumulation of multiple genetic changes. Chromosomal translocation is always thought to be accompanied with the fusion chimeric products. To data, the role of the fusion chimeric transcript remains obscure. Materials and Methods We performed RNA sequencing to detect the fusion genes in ten NPC tissues. Sanger sequencing and quantitative RT-PCR were used to measure the level of the fusion chimeric transcript in NPC tissues and cell lines. The functional experiments such as CCK8 assay, colony formation, and migration/invasion were conducted to analyze the role of this transcript in NPC in vitro. Results We demonstrated that the chimeric transcript SEPT7P2-PSPH was formed by trans-splicing of adjacent genes in the absence of chromosomal rearrangement and observed in both NPC patients and cell lines in parallel. Low-expression of the SEPT7P2-PSPH chimeric transcript induced the protein expression of PSPH and promoted cell proliferation, metastasis/invasion, and transforming ability in vitro. Conclusions Our findings indicate that the chimeric transcript SEPT7P2-PSPH is a product of trans-splicing of two adjacent genes and might be a tumor suppressor gene, potentially having the role of anticancer activity.
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Rose AM. Cancer and the junkyard chromosome: how repeat DNA sequence on chromosome 19 influences risk of malignant disease. Oncotarget 2018; 9:31942-31944. [PMID: 30174787 PMCID: PMC6112826 DOI: 10.18632/oncotarget.25873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 07/23/2018] [Indexed: 01/03/2023] Open
Affiliation(s)
- Anna M Rose
- MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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18
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He Y, Yuan C, Chen L, Lei M, Zellmer L, Huang H, Liao DJ. Transcriptional-Readthrough RNAs Reflect the Phenomenon of "A Gene Contains Gene(s)" or "Gene(s) within a Gene" in the Human Genome, and Thus Are Not Chimeric RNAs. Genes (Basel) 2018; 9:E40. [PMID: 29337901 PMCID: PMC5793191 DOI: 10.3390/genes9010040] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/29/2017] [Accepted: 01/07/2018] [Indexed: 02/06/2023] Open
Abstract
Tens of thousands of chimeric RNAs, i.e., RNAs with sequences of two genes, have been identified in human cells. Most of them are formed by two neighboring genes on the same chromosome and are considered to be derived via transcriptional readthrough, but a true readthrough event still awaits more evidence and trans-splicing that joins two transcripts together remains as a possible mechanism. We regard those genomic loci that are transcriptionally read through as unannotated genes, because their transcriptional and posttranscriptional regulations are the same as those of already-annotated genes, including fusion genes formed due to genetic alterations. Therefore, readthrough RNAs and fusion-gene-derived RNAs are not chimeras. Only those two-gene RNAs formed at the RNA level, likely via trans-splicing, without corresponding genes as genomic parents, should be regarded as authentic chimeric RNAs. However, since in human cells, procedural and mechanistic details of trans-splicing have never been disclosed, we doubt the existence of trans-splicing. Therefore, there are probably no authentic chimeras in humans, after readthrough and fusion-gene derived RNAs are all put back into the group of ordinary RNAs. Therefore, it should be further determined whether in human cells all two-neighboring-gene RNAs are derived from transcriptional readthrough and whether trans-splicing truly exists.
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Affiliation(s)
- Yan He
- Key Lab of Endemic and Ethnic Diseases of the Ministry of Education of China in Guizhou Medical University, Guiyang 550004, Guizhou, China.
| | - Chengfu Yuan
- Department of Biochemistry, China Three Gorges University, Yichang City 443002, Hubei, China.
| | - Lichan Chen
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA.
| | - Mingjuan Lei
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA.
| | - Lucas Zellmer
- Masonic Cancer Center, University of Minnesota, 435 E. River Road, Minneapolis, MN 55455, USA.
| | - Hai Huang
- School of Clinical Laboratory Science, Guizhou Medical University, Guiyang 550004, Guizhou, China.
| | - Dezhong Joshua Liao
- Key Lab of Endemic and Ethnic Diseases of the Ministry of Education of China in Guizhou Medical University, Guiyang 550004, Guizhou, China.
- Department of Pathology, Guizhou Medical University Hospital, Guiyang 550004, Guizhou, China.
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A microsatellite repeat in PCA3 long non-coding RNA is associated with prostate cancer risk and aggressiveness. Sci Rep 2017; 7:16862. [PMID: 29203868 PMCID: PMC5715103 DOI: 10.1038/s41598-017-16700-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/10/2017] [Indexed: 01/08/2023] Open
Abstract
Short tandem repeats (STRs) are repetitive sequences of a polymorphic stretch of two to six nucleotides. We hypothesized that STRs are associated with prostate cancer development and/or progression. We undertook RNA sequencing analysis of prostate tumors and adjacent non-malignant cells to identify polymorphic STRs that are readily expressed in these cells. Most of the expressed STRs in the clinical samples mapped to intronic and intergenic DNA. Our analysis indicated that three of these STRs (TAAA-ACTG2, TTTTG-TRIB1, and TG-PCA3) are polymorphic and differentially expressed in prostate tumors compared to adjacent non-malignant cells. TG-PCA3 STR expression was repressed by the anti-androgen drug enzalutamide in prostate cancer cells. Genetic analysis of prostate cancer patients and healthy controls (N > 2,000) showed a significant association of the most common 11 repeat allele of TG-PCA3 STR with prostate cancer risk (OR = 1.49; 95% CI 1.11–1.99; P = 0.008). A significant association was also observed with aggressive disease (OR = 2.00; 95% CI 1.06–3.76; P = 0.031) and high mortality rates (HR = 3.0; 95% CI 1.03–8.77; P = 0.045). We propose that TG-PCA3 STR has both diagnostic and prognostic potential for prostate cancer. We provided a proof of concept to be applied to other RNA sequencing datasets to identify disease-associated STRs for future clinical exploratory studies.
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It Is Imperative to Establish a Pellucid Definition of Chimeric RNA and to Clear Up a Lot of Confusion in the Relevant Research. Int J Mol Sci 2017; 18:ijms18040714. [PMID: 28350330 PMCID: PMC5412300 DOI: 10.3390/ijms18040714] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/15/2017] [Accepted: 03/17/2017] [Indexed: 12/27/2022] Open
Abstract
There have been tens of thousands of RNAs deposited in different databases that contain sequences of two genes and are coined chimeric RNAs, or chimeras. However, "chimeric RNA" has never been lucidly defined, partly because "gene" itself is still ill-defined and because the means of production for many RNAs is unclear. Since the number of putative chimeras is soaring, it is imperative to establish a pellucid definition for it, in order to differentiate chimeras from regular RNAs. Otherwise, not only will chimeric RNA studies be misled but also characterization of fusion genes and unannotated genes will be hindered. We propose that only those RNAs that are formed by joining two RNA transcripts together without a fusion gene as a genomic basis should be regarded as authentic chimeras, whereas those RNAs transcribed as, and cis-spliced from, single transcripts should not be deemed as chimeras. Many RNAs containing sequences of two neighboring genes may be transcribed via a readthrough mechanism, and thus are actually RNAs of unannotated genes or RNA variants of known genes, but not chimeras. In today's chimeric RNA research, there are still several key flaws, technical constraints and understudied tasks, which are also described in this perspective essay.
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21
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Lai J, An J, Srinivasan S, Clements JA, Batra J. A computational analysis of the genetic and transcript diversity at the kallikrein locus. Biol Chem 2016; 397:1307-1313. [DOI: 10.1515/hsz-2016-0161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/09/2016] [Indexed: 11/15/2022]
Abstract
Abstract
The kallikrein related peptidase gene family (KLKs) comprises 15 genes located between 19q13.3-13.4. KLKs have chymotrypsin and/or trypsin like activity, but the tissue/organ expression profile of each KLK varies considerably. Thus, the role of KLKs in human biology is also very diverse, and the deregulation of their function results in a wide-range of diseases. Here, we have cataloged the transcript (variants and fusions) and genetic (single nucleotide polymorphisms, small insertions/deletions, copy number variations (CNVs), and short tandem repeats) diversity at the KLK locus, providing a data set for researchers to explore the mechanisms through which KLK function may be deregulated. We reveal that the KLK locus hosts 85 fusion transcripts, and 80 variant transcripts. Interestingly, some fusion transcripts comprise up to 6 KLK genes. Our analysis of genetic variations of 2504 individuals from the 1000 Genome Project indicated that the KLK locus is rich in genetic diversity, with some fusion transcripts harboring over 1000 single nucleotide variations. We also found evidence from the literature linking 2387 KLK genetic variants with many types of diseases. Finally, genotyping data from the 131 KLK genetic variants in the NCI-60 cancer cell lines is provided as a resource for the cancer and KLK field.
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22
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Lee SJ, Kim MJ, Kwon IC, Roberts TM. Delivery strategies and potential targets for siRNA in major cancer types. Adv Drug Deliv Rev 2016; 104:2-15. [PMID: 27259398 DOI: 10.1016/j.addr.2016.05.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 02/24/2016] [Accepted: 05/15/2016] [Indexed: 02/08/2023]
Abstract
Small interfering RNA (siRNA) has gained attention as a potential therapeutic reagent due to its ability to inhibit specific genes in many genetic diseases. For many years, studies of siRNA have progressively advanced toward novel treatment strategies against cancer. Cancer is caused by various mutations in hundreds of genes including both proto-oncogenes and tumor suppressor genes. In order to develop siRNAs as therapeutic agents for cancer treatment, delivery strategies for siRNA must be carefully designed and potential gene targets carefully selected for optimal anti-cancer effects. In this review, various modifications and delivery strategies for siRNA delivery are discussed. In addition, we present current thinking on target gene selection in major tumor types.
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23
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Lai J, An J, Seim I, Walpole C, Hoffman A, Moya L, Srinivasan S, Perry-Keene JL, Wang C, Lehman ML, Nelson CC, Clements JA, Batra J. Fusion transcript loci share many genomic features with non-fusion loci. BMC Genomics 2015; 16:1021. [PMID: 26626734 PMCID: PMC4667522 DOI: 10.1186/s12864-015-2235-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/23/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fusion transcripts are found in many tissues and have the potential to create novel functional products. Here, we investigate the genomic sequences around fusion junctions to better understand the transcriptional mechanisms mediating fusion transcription/splicing. We analyzed data from prostate (cancer) cells as previous studies have shown extensively that these cells readily undergo fusion transcription. RESULTS We used the FusionMap program to identify high-confidence fusion transcripts from RNAseq data. The RNAseq datasets were from our (N = 8) and other (N = 14) clinical prostate tumors with adjacent non-cancer cells, and from the LNCaP prostate cancer cell line that were mock-, androgen- (DHT), and anti-androgen- (bicalutamide, enzalutamide) treated. In total, 185 fusion transcripts were identified from all RNAseq datasets. The majority (76%) of these fusion transcripts were 'read-through chimeras' derived from adjacent genes in the genome. Characterization of sequences at fusion loci were carried out using a combination of the FusionMap program, custom Perl scripts, and the RNAfold program. Our computational analysis indicated that most fusion junctions (76%) use the consensus GT-AG intron donor-acceptor splice site, and most fusion transcripts (85%) maintained the open reading frame. We assessed whether parental genes of fusion transcripts have the potential to form complementary base pairing between parental genes which might bring them into physical proximity. Our computational analysis of sequences flanking fusion junctions at parental loci indicate that these loci have a similar propensity as non-fusion loci to hybridize. The abundance of repetitive sequences at fusion and non-fusion loci was also investigated given that SINE repeats are involved in aberrant gene transcription. We found few instances of repetitive sequences at both fusion and non-fusion junctions. Finally, RT-qPCR was performed on RNA from both clinical prostate tumors and adjacent non-cancer cells (N = 7), and LNCaP cells treated as above to validate the expression of seven fusion transcripts and their respective parental genes. We reveal that fusion transcript expression is similar to the expression of parental genes. CONCLUSIONS Fusion transcripts maintain the open reading frame, and likely use the same transcriptional machinery as non-fusion transcripts as they share many genomic features at splice/fusion junctions.
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Affiliation(s)
- John Lai
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. .,Current address: Genetic Technologies, 60-66 Hanover Street, Melbourne, Australia.
| | - Jiyuan An
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Inge Seim
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. .,Comparative and Endocrine Biology Laboratory, Institute of Health and Biomedical Innovation, Brisbane, Australia. .,Ghrelin Research Group, Institute of Health and Biomedical Innovation, Brisbane, Australia.
| | - Carina Walpole
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Andrea Hoffman
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Leire Moya
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Srilakshmi Srinivasan
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | | | | | - Chenwei Wang
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Melanie L Lehman
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Colleen C Nelson
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Judith A Clements
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
| | - Jyotsna Batra
- Australian Prostate Cancer Research Centre - Queensland, Translational Research Institute, Brisbane, Australia. .,Cancer and Molecular Medicine Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
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Jin Y, Wang L, Qu S, Sheng X, Kristian A, Mælandsmo GM, Pällmann N, Yuca E, Tekedereli I, Gorgulu K, Alpay N, Sood A, Lopez-Berestein G, Fazli L, Rennie P, Risberg B, Wæhre H, Danielsen HE, Ozpolat B, Saatcioglu F. STAMP2 increases oxidative stress and is critical for prostate cancer. EMBO Mol Med 2015; 7:315-31. [PMID: 25680860 PMCID: PMC4364948 DOI: 10.15252/emmm.201404181] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The six transmembrane protein of prostate 2 (STAMP2) is an androgen-regulated gene whose mRNA expression is increased in prostate cancer (PCa). Here, we show that STAMP2 protein expression is increased in human PCa compared with benign prostate that is also correlated with tumor grade and treatment response. We also show that STAMP2 significantly increased reactive oxygen species (ROS) in PCa cells through its iron reductase activity which also depleted NADPH levels. Knockdown of STAMP2 expression in PCa cells inhibited proliferation, colony formation, and anchorage-independent growth, and significantly increased apoptosis. Furthermore, STAMP2 effects were, at least in part, mediated by activating transcription factor 4 (ATF4), whose expression is regulated by ROS. Consistent with in vitro findings, silencing STAMP2 significantly inhibited PCa xenograft growth in mice. Finally, therapeutic silencing of STAMP2 by systemically administered nanoliposomal siRNA profoundly inhibited tumor growth in two established preclinical PCa models in mice. These data suggest that STAMP2 is required for PCa progression and thus may serve as a novel therapeutic target.
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Affiliation(s)
- Yang Jin
- Department of Biosciences, University of Oslo, Oslo, Norway Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
| | - Ling Wang
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Su Qu
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Xia Sheng
- Department of Biosciences, University of Oslo, Oslo, Norway Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
| | | | | | - Nora Pällmann
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Erkan Yuca
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | - Ibrahim Tekedereli
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | - Kivanc Gorgulu
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | - Neslihan Alpay
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | - Anil Sood
- Gynecological Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | | | - Ladan Fazli
- The Vancouver Prostate Centre, Vancouver, BC, Canada
| | - Paul Rennie
- The Vancouver Prostate Centre, Vancouver, BC, Canada
| | - Bjørn Risberg
- Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway Division of Pathology, Oslo University Hospital, Oslo, Norway Division of Surgery, Oslo University Hospital, Oslo, Norway
| | - Håkon Wæhre
- Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway Division of Pathology, Oslo University Hospital, Oslo, Norway Division of Surgery, Oslo University Hospital, Oslo, Norway Center for Cancer Biomedicine, University of Oslo, Oslo, Norway
| | - Håvard E Danielsen
- Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway Center for Cancer Biomedicine, University of Oslo, Oslo, Norway Department of Informatics, University of Oslo, Oslo, Norway
| | - Bulent Ozpolat
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA
| | - Fahri Saatcioglu
- Department of Biosciences, University of Oslo, Oslo, Norway Institute for Cancer Genetics and Informatics, Oslo University Hospital, Oslo, Norway
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Peng Z, Yuan C, Zellmer L, Liu S, Xu N, Liao DJ. Hypothesis: Artifacts, Including Spurious Chimeric RNAs with a Short Homologous Sequence, Caused by Consecutive Reverse Transcriptions and Endogenous Random Primers. J Cancer 2015; 6:555-67. [PMID: 26000048 PMCID: PMC4439942 DOI: 10.7150/jca.11997] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 04/02/2015] [Indexed: 12/21/2022] Open
Abstract
Recent RNA-sequencing technology and associated bioinformatics have led to identification of tens of thousands of putative human chimeric RNAs, i.e. RNAs containing sequences from two different genes, most of which are derived from neighboring genes on the same chromosome. In this essay, we redefine "two neighboring genes" as those producing individual transcripts, and point out two known mechanisms for chimeric RNA formation, i.e. transcription from a fusion gene or trans-splicing of two RNAs. By our definition, most putative RNA chimeras derived from canonically-defined neighboring genes may either be technical artifacts or be cis-splicing products of 5'- or 3'-extended RNA of either partner that is redefined herein as an unannotated gene, whereas trans-splicing events are rare in human cells. Therefore, most authentic chimeric RNAs result from fusion genes, about 1,000 of which have been identified hitherto. We propose a hypothesis of "consecutive reverse transcriptions (RTs)", i.e. another RT reaction following the previous one, for how most spurious chimeric RNAs, especially those containing a short homologous sequence, may be generated during RT, especially in RNA-sequencing wherein RNAs are fragmented. We also point out that RNA samples contain numerous RNA and DNA shreds that can serve as endogenous random primers for RT and ensuing polymerase chain reactions (PCR), creating artifacts in RT-PCR.
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Affiliation(s)
- Zhiyu Peng
- 1. Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen 518083, P. R. China
| | - Chengfu Yuan
- 2. Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Lucas Zellmer
- 2. Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Siqi Liu
- 3. CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Ningzhi Xu
- 4. Laboratory of Cell and Molecular Biology, Cancer Institute, Chinese Academy of Medical Science, Beijing 100021, P. R. China
| | - D Joshua Liao
- 2. Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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An J, Lai J, Wood DLA, Sajjanhar A, Wang C, Tevz G, Lehman ML, Nelson CC. RNASeqBrowser: a genome browser for simultaneous visualization of raw strand specific RNAseq reads and UCSC genome browser custom tracks. BMC Genomics 2015; 16:145. [PMID: 25766521 PMCID: PMC4355470 DOI: 10.1186/s12864-015-1346-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Strand specific RNAseq data is now more common in RNAseq projects. Visualizing RNAseq data has become an important matter in Analysis of sequencing data. The most widely used visualization tool is the UCSC genome browser that introduced the custom track concept that enabled researchers to simultaneously visualize gene expression at a particular locus from multiple experiments. Our objective of the software tool is to provide friendly interface for visualization of RNAseq datasets. RESULTS This paper introduces a visualization tool (RNASeqBrowser) that incorporates and extends the functionality of the UCSC genome browser. For example, RNASeqBrowser simultaneously displays read coverage, SNPs, InDels and raw read tracks with other BED and wiggle tracks -- all being dynamically built from the BAM file. Paired reads are also connected in the browser to enable easier identification of novel exon/intron borders and chimaeric transcripts. Strand specific RNAseq data is also supported by RNASeqBrowser that displays reads above (positive strand transcript) or below (negative strand transcripts) a central line. Finally, RNASeqBrowser was designed for ease of use for users with few bioinformatic skills, and incorporates the features of many genome browsers into one platform. CONCLUSIONS The features of RNASeqBrowser: (1) RNASeqBrowser integrates UCSC genome browser and NGS visualization tools such as IGV. It extends the functionality of the UCSC genome browser by adding several new types of tracks to show NGS data such as individual raw reads, SNPs and InDels. (2) RNASeqBrowser can dynamically generate RNA secondary structure. It is useful for identifying non-coding RNA such as miRNA. (3) Overlaying NGS wiggle data is helpful in displaying differential expression and is simple to implement in RNASeqBrowser. (4) NGS data accumulates a lot of raw reads. Thus, RNASeqBrowser collapses exact duplicate reads to reduce visualization space. Normal PC's can show many windows of NGS individual raw reads without much delay. (5) Multiple popup windows of individual raw reads provide users with more viewing space. This avoids existing approaches (such as IGV) which squeeze all raw reads into one window. This will be helpful for visualizing multiple datasets simultaneously. RNASeqBrowser and its manual are freely available at http://www.australianprostatecentre.org/research/software/rnaseqbrowser or http://sourceforge.net/projects/rnaseqbrowser/.
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Affiliation(s)
- Jiyuan An
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
| | - John Lai
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
| | - David L A Wood
- Queensland Centre for Medical Genomics, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, 4072, Australia.
| | - Atul Sajjanhar
- School of Information Technology, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
| | - Chenwei Wang
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
| | - Gregor Tevz
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
| | - Melanie L Lehman
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
| | - Colleen C Nelson
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, 4102, Australia.
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Bianchessi V, Badi I, Bertolotti M, Nigro P, D'Alessandra Y, Capogrossi MC, Zanobini M, Pompilio G, Raucci A, Lauri A. The mitochondrial lncRNA ASncmtRNA-2 is induced in aging and replicative senescence in Endothelial Cells. J Mol Cell Cardiol 2015; 81:62-70. [PMID: 25640160 DOI: 10.1016/j.yjmcc.2015.01.012] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/12/2014] [Accepted: 01/04/2015] [Indexed: 01/23/2023]
Abstract
Age-associated cardiovascular diseases are at least partially ascribable to vascular cell senescence. Replicative senescence (RS) and stress-induced premature senescence (SIPS) are provoked respectively by endogenous (telomere erosion) and exogenous (H2O2, UV) stimuli resulting in cell cycle arrest in G1 and G2 phases. In both scenarios, mitochondria-derived ROS are important players in senescence initiation. We aimed to define whether a mtDNA-transcribed long-non-coding-RNA (lncRNA), ASncmtRNA-2, has a role in vascular aging and senescence. Aortas of old mice, characterized by increased senescence, showed an increment in ASncmtRNA-2 expression. In vitro analysis of Endothelial Cells (EC) and Vascular Smooth Muscle Cells (VSMC) established that ASncmtRNA-2 is induced in EC, but not in VSMC, during RS. Surprisingly, ASncmtRNA-2 is not upregulated in two different EC SIPS scenarios, treated with H2O2 and UV. The p16 gene displayed similar ASncmtRNA-2 expression patterns, suggesting a possible co-regulation of the two genes. Interestingly, the expression of two miRNAs, hsa-miR-4485 and hsa-miR-1973, with perfect homology to the double strand region of ASncmtRNA-2 and originating at least in part from a mitochondrial transcript, was induced in RS, opening to the possibility that this lncRNA functions as a non-canonical precursor of these miRNAs. Cell cycle analysis of EC transiently over-expressing ASncmtRNA-2 revealed an accumulation of EC in the G2/M phase, but not in the G1 phase. We propose that ASncmtRNA-2 in EC might be involved in the RS establishment by participating in the cell cycle arrest in G2/M phase, possibly through the production of hsa-miR-4485 and hsa-miR-1973. This article is part of a Special Issue entitled: Mitochondria.
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Affiliation(s)
- Valentina Bianchessi
- Unità di Biologia Vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Ileana Badi
- Unità di Cardio-Oncologia Sperimentale e Invecchiamento Cardiovascolare, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Matteo Bertolotti
- Unità di Cardio-Oncologia Sperimentale e Invecchiamento Cardiovascolare, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Patrizia Nigro
- Unità di Biologia Vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Yuri D'Alessandra
- Unità di Immunologia e Genomica Funzionale, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Maurizio C Capogrossi
- Laboratorio di Patologia Vascolare, Istituto Dermopatico dell'Immacolata (IDI), IRCCS, Roma, Italy
| | - Marco Zanobini
- Dipartimento di Chirurgia Vascolare, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Giulio Pompilio
- Unità di Biologia Vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Angela Raucci
- Unità di Cardio-Oncologia Sperimentale e Invecchiamento Cardiovascolare, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy
| | - Andrea Lauri
- Unità di Biologia Vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino (CCM), IRCCS, Milano, Italy.
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Xiao-Jie L, Ai-Mei G, Li-Juan J, Jiang X. Pseudogene in cancer: real functions and promising signature. J Med Genet 2014; 52:17-24. [DOI: 10.1136/jmedgenet-2014-102785] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Jividen K, Li H. Chimeric RNAs generated by intergenic splicing in normal and cancer cells. Genes Chromosomes Cancer 2014; 53:963-71. [PMID: 25131334 DOI: 10.1002/gcc.22207] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 07/16/2014] [Indexed: 12/30/2022] Open
Abstract
A hallmark of many neoplasias is chromosomal rearrangement, an event that commonly results in the fusion of two separate genes. The RNA and protein resulting from these gene fusions often play critical roles in cancer development, maintenance, and progression. Traditionally, these fusion products are thought to be produced solely due to DNA level changes and are therefore considered unique to cancer. Recent advances in microarray and deep-sequencing have revealed many more fusion transcripts. Surprisingly, some are without detectable rearrangement at the DNA level. Reports have demonstrated that at least some of these chimeric RNAs are generated via intergenic splicing. In this review, we highlight three examples of these noncanonical chimeric transcripts that are formed by trans-splicing or cis-splicing of adjacent genes and summarize the knowledge we have regarding these noncanonical fusions. We discuss the implications of the chimeric RNAs in both cancer and normal physiology, as some of these fusion transcripts are found in normal, noncancerous cells with sequences identical to those generated by canonical chromosomal translocation found in cancer cells. Finally, we present methods that are currently being used to discover additional chimeric RNAs.
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Affiliation(s)
- Kasey Jividen
- Department of Pathology, University of Virginia, Charlottesville, VA
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Molecular circuit involving KLK4 integrates androgen and mTOR signaling in prostate cancer. Proc Natl Acad Sci U S A 2013; 110:E2572-81. [PMID: 23798432 DOI: 10.1073/pnas.1304318110] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The androgen receptor (AR) and the phosphoinositide 3-kinase (PI3K)/protein kinase B/mammalian target of rapamycin (mTOR) signaling are two of the major proliferative pathways in a number of tissues and are the main therapeutic targets in various disorders, including prostate cancer (PCa). Previous work has shown that there is reciprocal feedback regulation of PI3K and AR signaling in PCa, suggesting that cotargeting both pathways may enhance therapeutic efficacy. Here we show that proteins encoded by two androgen-regulated genes, kallikrein related peptidase 4 (KLK4) and promyelocytic leukemia zinc finger (PLZF), integrate optimal functioning of AR and mTOR signaling in PCa cells. KLK4 interacts with PLZF and decreases its stability. PLZF in turn interacts with AR and inhibits its function as a transcription factor. PLZF also activates expression of regulated in development and DNA damage responses 1, an inhibitor of mTORC1. Thus, a unique molecular switch is generated that regulates both AR and PI3K signaling. Consistently, KLK4 knockdown results in a significant decline in PCa cell proliferation in vitro and in vivo, decreases anchorage-independent growth, induces apoptosis, and dramatically sensitizes PCa cells to apoptosis-inducing agents. Furthermore, in vivo nanoliposomal KLK4 siRNA delivery in mice bearing PCa tumors results in profound remission. These results demonstrate that the activities of AR and mTOR pathways are maintained by KLK4, which may thus be a viable target for therapy.
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Whiteside EJ, Seim I, Pauli JP, O'Keeffe AJ, Thomas PB, Carter SL, Walpole CM, Fung JNT, Josh P, Herington AC, Chopin LK. Identification of a long non-coding RNA gene, growth hormone secretagogue receptor opposite strand, which stimulates cell migration in non-small cell lung cancer cell lines. Int J Oncol 2013; 43:566-74. [PMID: 23722988 DOI: 10.3892/ijo.2013.1969] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 03/07/2013] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms involved in non‑small cell lung cancer tumourigenesis are largely unknown; however, recent studies have suggested that long non-coding RNAs (lncRNAs) are likely to play a role. In this study, we used public databases to identify an mRNA-like, candidate long non-coding RNA, GHSROS (GHSR opposite strand), transcribed from the antisense strand of the ghrelin receptor gene, growth hormone secretagogue receptor (GHSR). Quantitative real-time RT-PCR revealed higher expression of GHSROS in lung cancer tissue compared to adjacent, non-tumour lung tissue. In common with many long non-coding RNAs, GHSROS is 5' capped and 3' polyadenylated (mRNA-like), lacks an extensive open reading frame and harbours a transposable element. Engineered overexpression of GHSROS stimulated cell migration in the A549 and NCI-H1299 non-small cell lung cancer cell lines, but suppressed cell migration in the Beas-2B normal lung-derived bronchoepithelial cell line. This suggests that GHSROS function may be dependent on the oncogenic context. The identification of GHSROS, which is expressed in lung cancer and stimulates cell migration in lung cancer cell lines, contributes to the growing number of non-coding RNAs that play a role in the regulation of tumourigenesis and metastatic cancer progression.
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Affiliation(s)
- Eliza J Whiteside
- Ghrelin Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
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Kalyana-Sundaram S, Kumar-Sinha C, Shankar S, Robinson DR, Wu YM, Cao X, Asangani IA, Kothari V, Prensner JR, Lonigro RJ, Iyer MK, Barrette T, Shanmugam A, Dhanasekaran SM, Palanisamy N, Chinnaiyan AM. Expressed pseudogenes in the transcriptional landscape of human cancers. Cell 2012; 149:1622-34. [PMID: 22726445 DOI: 10.1016/j.cell.2012.04.041] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 01/10/2012] [Accepted: 04/26/2012] [Indexed: 12/12/2022]
Abstract
Pseudogene transcripts can provide a novel tier of gene regulation through generation of endogenous siRNAs or miRNA-binding sites. Characterization of pseudogene expression, however, has remained confined to anecdotal observations due to analytical challenges posed by the extremely close sequence similarity with their counterpart coding genes. Here, we describe a systematic analysis of pseudogene "transcription" from an RNA-Seq resource of 293 samples, representing 13 cancer and normal tissue types, and observe a surprisingly prevalent, genome-wide expression of pseudogenes that could be categorized as ubiquitously expressed or lineage and/or cancer specific. Further, we explore disease subtype specificity and functions of selected expressed pseudogenes. Taken together, we provide evidence that transcribed pseudogenes are a significant contributor to the transcriptional landscape of cells and are positioned to play significant roles in cellular differentiation and cancer progression, especially in light of the recently described ceRNA networks. Our work provides a transcriptome resource that enables high-throughput analyses of pseudogene expression.
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Lawrence MG, Stephens CR, Need EF, Lai J, Buchanan G, Clements JA. Long terminal repeats act as androgen-responsive enhancers for the PSA-kallikrein locus. Endocrinology 2012; 153:3199-210. [PMID: 22597536 DOI: 10.1210/en.2012-1267] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The androgen receptor (AR) signaling pathway is a common therapeutic target for prostate cancer, because it is critical for the survival of both hormone-responsive and castrate-resistant tumor cells. Most of the detailed understanding that we have of AR transcriptional activation has been gained by studying classical target genes. For more than two decades, Kallikrein 3 (KLK3) (prostate-specific antigen) has been used as a prototypical AR target gene, because it is highly androgen responsive in prostate cancer cells. Three regions upstream of the KLK3 gene, including the distal enhancer, are known to contain consensus androgen-responsive elements required for AR-mediated transcriptional activation. Here, we show that KLK3 is one of a specific cluster of androgen-regulated genes at the centromeric end of the kallikrein locus with enhancers that evolved from the long terminal repeat (LTR) (LTR40a) of an endogenous retrovirus. Ligand-dependent recruitment of the AR to individual LTR-derived enhancers results in concurrent up-regulation of endogenous KLK2, KLK3, and KLKP1 expression in LNCaP prostate cancer cells. At the molecular level, a kallikrein-specific duplication within the LTR is required for maximal androgen responsiveness. Therefore, KLK3 represents a subset of target genes regulated by repetitive elements but is not typical of the whole spectrum of androgen-responsive transcripts. These data provide a novel and more detailed understanding of AR transcriptional activation and emphasize the importance of repetitive elements as functional regulatory units.
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Affiliation(s)
- Mitchell G Lawrence
- Australian Prostate Cancer Research Centre-Queensland, Institute of Health and Biomedical Innovation Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Queensland 4059, Australia
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Abstract
Trans-splicing is the joining together of portions of two separate pre-mRNA molecules. The two distinct categories of spliceosomal trans-splicing are genic trans-splicing, which joins exons of different pre-mRNA transcripts, and spliced leader (SL) trans-splicing, which involves an exon donated from a specialized SL RNA. Both depend primarily on the same signals and components as cis-splicing. Genic trans-splicing events producing protein-coding mRNAs have been described in a variety of organisms, including Caenorhabditis elegans and Drosophila. In mammalian cells, genic trans-splicing can be associated with cancers and translocations. SL trans-splicing has mainly been studied in nematodes and trypanosomes, but there are now numerous and diverse phyla (including primitive chordates) where this type of trans-splicing has been detected. Such diversity raises questions as to the evolutionary origin of the process. Another intriguing question concerns the function of trans-splicing, as operon resolution can only account for a small proportion of the total amount of SL trans-splicing.
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Affiliation(s)
- Erika L Lasda
- University of Colorado Denver, Department of Biochemistry and Molecular Genetics; University of Colorado Boulder, Department of Molecular, Cellular, and Developmental Biology
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