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Smolander J, Khan S, Singaravelu K, Kauko L, Lund RJ, Laiho A, Elo LL. Evaluation of tools for identifying large copy number variations from ultra-low-coverage whole-genome sequencing data. BMC Genomics 2021; 22:357. [PMID: 34000988 PMCID: PMC8130438 DOI: 10.1186/s12864-021-07686-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/07/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Detection of copy number variations (CNVs) from high-throughput next-generation whole-genome sequencing (WGS) data has become a widely used research method during the recent years. However, only a little is known about the applicability of the developed algorithms to ultra-low-coverage (0.0005-0.8×) data that is used in various research and clinical applications, such as digital karyotyping and single-cell CNV detection. RESULT Here, the performance of six popular read-depth based CNV detection algorithms (BIC-seq2, Canvas, CNVnator, FREEC, HMMcopy, and QDNAseq) was studied using ultra-low-coverage WGS data. Real-world array- and karyotyping kit-based validation were used as a benchmark in the evaluation. Additionally, ultra-low-coverage WGS data was simulated to investigate the ability of the algorithms to identify CNVs in the sex chromosomes and the theoretical minimum coverage at which these tools can accurately function. Our results suggest that while all the methods were able to detect large CNVs, many methods were susceptible to producing false positives when smaller CNVs (< 2 Mbp) were detected. There was also significant variability in their ability to identify CNVs in the sex chromosomes. Overall, BIC-seq2 was found to be the best method in terms of statistical performance. However, its significant drawback was by far the slowest runtime among the methods (> 3 h) compared with FREEC (~ 3 min), which we considered the second-best method. CONCLUSIONS Our comparative analysis demonstrates that CNV detection from ultra-low-coverage WGS data can be a highly accurate method for the detection of large copy number variations when their length is in millions of base pairs. These findings facilitate applications that utilize ultra-low-coverage CNV detection.
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Affiliation(s)
- Johannes Smolander
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Sofia Khan
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Kalaimathy Singaravelu
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Leni Kauko
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Riikka J Lund
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Asta Laiho
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Laura L Elo
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland.
- Institute of Biomedicine, University of Turku, 20520, Turku, Finland.
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Lund RJ, Rahkonen N, Malonzo M, Kauko L, Emani MR, Kivinen V, Närvä E, Kemppainen E, Laiho A, Skottman H, Hovatta O, Rasool O, Nykter M, Lähdesmäki H, Lahesmaa R. RNA Polymerase III Subunit POLR3G Regulates Specific Subsets of PolyA + and SmallRNA Transcriptomes and Splicing in Human Pluripotent Stem Cells. Stem Cell Reports 2018; 8:1442-1454. [PMID: 28494942 PMCID: PMC5425787 DOI: 10.1016/j.stemcr.2017.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [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: 08/13/2016] [Revised: 04/13/2017] [Accepted: 04/13/2017] [Indexed: 11/17/2022] Open
Abstract
POLR3G is expressed at high levels in human pluripotent stem cells (hPSCs) and is required for maintenance of stem cell state through mechanisms not known in detail. To explore how POLR3G regulates stem cell state, we carried out deep-sequencing analysis of polyA+ and smallRNA transcriptomes present in hPSCs and regulated in POLR3G-dependent manner. Our data reveal that POLR3G regulates a specific subset of the hPSC transcriptome, including multiple transcript types, such as protein-coding genes, long intervening non-coding RNAs, microRNAs and small nucleolar RNAs, and affects RNA splicing. The primary function of POLR3G is in the maintenance rather than repression of transcription. The majority of POLR3G polyA+ transcriptome is regulated during differentiation, and the key pluripotency factors bind to the promoters of at least 30% of the POLR3G-regulated transcripts. Among the direct targets of POLR3G, POLG is potentially important in sustaining stem cell status in a POLR3G-dependent manner.
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Affiliation(s)
- Riikka J Lund
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland.
| | - Nelly Rahkonen
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Maia Malonzo
- Department of Computer Science, Aalto University, Espoo 02150, Finland
| | - Leni Kauko
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Maheswara Reddy Emani
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Virpi Kivinen
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere 33014, Finland
| | - Elisa Närvä
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Esko Kemppainen
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Asta Laiho
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Heli Skottman
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere 33014, Finland
| | - Outi Hovatta
- Department CLINTEC, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm 171 77, Sweden
| | - Omid Rasool
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
| | - Matti Nykter
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland; Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere 33014, Finland
| | - Harri Lähdesmäki
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland; Department of Computer Science, Aalto University, Espoo 02150, Finland
| | - Riitta Lahesmaa
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20520, Finland
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Väänänen RM, Lilja H, Kauko L, Helo P, Kekki H, Cronin AM, Vickers AJ, Nurmi M, Alanen K, Bjartell A, Pettersson K. Cancer-associated changes in the expression of TMPRSS2-ERG, PCA3, and SPINK1 in histologically benign tissue from cancerous vs noncancerous prostatectomy specimens. Urology 2014; 83:511.e1-7. [PMID: 24468524 DOI: 10.1016/j.urology.2013.11.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/15/2013] [Accepted: 11/04/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate whether messenger ribonucleic acid (mRNA) expression of TMPRSS2-ERG fusion gene, a suggested prostate cancer (PCa) biomarker, was specific to cancerous lesions alone and to study the expression of SPINK1 and PCA3 mRNAs in the same cohort to also explore the proposed mutual exclusivity of TMPRSS2-ERG and SPINK1 expression. METHODS Levels of 2 TMPRSS2-ERG transcripts, PCA3, and SPINK1 mRNAs were measured with highly standardized reverse transcription quantitative polymerase chain reaction assays in cystoprostatectomy specimens from 19 patients with invasive bladder cancer and 174 radical prostatectomy (RP) samples (88 histologically benign prostate [HBP] tissues and 86 from cancerous lesions) from 87 patients with clinically localized PCa. RESULTS Expression of TMPRSS2-ERG transcripts was detected in 45 of 88 (51%) HBP tissues from RP specimens and more frequently (57 of 86, 66%) found in cancerous lesions. In contrast, TMPRSS2-ERG expression was detected in only 2 of 19 (11%) cystoprostatectomy specimens, both with incidental PCa foci elsewhere in the gland. Similar trends of changes in the expression of PCA3 and SPINK1 were present in HBP tissue from RP compared with cystoprostatectomy specimens. CONCLUSION Although the expression of TMPRSS2-ERG, SPINK1, and PCA3 mRNA is higher or more frequently found in cancerous lesions, HBP tissues from patients with clinically localized PCa manifest molecular, mRNA level changes that are absent in cystoprostatectomy specimens lacking incidental PCa foci or infrequent in cystoprostatectomy specimens containing incidental PCa. If this finding is replicated, these molecular assays could be used to inform men with negative biopsy results about the likelihood of cancerous lesions in unsampled regions and hence the need for repeat biopsy.
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Affiliation(s)
| | - Hans Lilja
- Departments of Laboratory Medicine, Surgery (Urology), and Medicine (GU-Oncology), Memorial Sloan-Kettering Cancer Center, New York, NY; Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom; Institute of Biomedical Technology, University of Tampere, Tampere, Finland; Department of Laboratory Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Leni Kauko
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Pauliina Helo
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Henna Kekki
- Department of Biotechnology, University of Turku, Turku, Finland
| | - Angel M Cronin
- Center for Outcomes and Policy Research, Dana-Farber Cancer Institute, Boston, MA
| | - Andrew J Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Martti Nurmi
- Department of Surgery, Turku University Hospital, Turku, Finland
| | - Kalle Alanen
- Department of Pathology, Turku University Hospital, Turku, Finland
| | - Anders Bjartell
- Department of Clinical Sciences, Division of Urological Cancers, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Kim Pettersson
- Department of Biotechnology, University of Turku, Turku, Finland
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Väänänen RM, Lilja H, Cronin A, Kauko L, Rissanen M, Kauko O, Kekki H, Vidbäck S, Nurmi M, Alanen K, Pettersson K. Association of transcript levels of 10 established or candidate-biomarker gene targets with cancerous versus non-cancerous prostate tissue from radical prostatectomy specimens. Clin Biochem 2013; 46:670-4. [PMID: 23391636 DOI: 10.1016/j.clinbiochem.2013.01.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 01/10/2013] [Accepted: 01/27/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The benefits of PSA (prostate specific antigen)-testing in prostate cancer remain controversial with a consequential need for validation of additional biomarkers. We used highly standardized reverse-transcription (RT)-PCR assays to compare transcript levels of 10 candidate cancer marker genes - BMP6, FGF-8b, KLK2, KLK3, KLK4, KLK15, MSMB, PCA3, PSCA and Trpm8 - in carefully ascertained non-cancerous versus cancerous prostate tissue from patients with clinically localized prostate cancer treated by radical prostatectomy. DESIGN AND METHODS Total RNA was isolated from fresh frozen prostate tissue procured immediately after resection from two separate areas in each of 87 radical prostatectomy specimens. Subsequent histopathological assessment classified 86 samples as cancerous and 88 as histologically benign prostate tissue. Variation in total RNA recovery was accounted for by using external and internal standards and enabled us to measure transcript levels by RT-PCR in a highly quantitative manner. RESULTS Of the ten genes, there were significantly higher levels only of one of the less abundant transcripts, PCA3, in cancerous versus non-cancerous prostate tissue whereas PSCA mRNA levels were significantly lower in cancerous versus histologically benign tissue. Advanced pathologic stage was associated with significantly higher expression of KLK15 and PCA3 mRNAs. Median transcript levels of the most abundantly expressed genes (i.e. MSMB, KLK3, KLK4 and KLK2) in prostate tissue were up to 10(5)-fold higher than those of other gene targets. CONCLUSIONS PCA3 expression was associated with advanced pathological stage but the magnitude of overexpression of PCA3 in cancerous versus non-cancerous prostate tissue was modest compared to previously reported data.
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