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Chen YY, Dagg R, Zhang Y, Lee JHY, Lu R, Martin La Rotta N, Sampl S, Korkut-Demirbaş M, Holzmann K, Lau LMS, Reddel RR, Henson JD. The C-Circle Biomarker Is Secreted by Alternative-Lengthening-of-Telomeres Positive Cancer Cells inside Exosomes and Provides a Blood-Based Diagnostic for ALT Activity. Cancers (Basel) 2021; 13:cancers13215369. [PMID: 34771533 PMCID: PMC8582556 DOI: 10.3390/cancers13215369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 07/19/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary A clinical test for alternative-lengthening-of-telomeres (ALT) could assist with cancer diagnosis and monitoring of disease progression. ALT-targeted anticancer treatments are being developed; however, there is no appropriate companion ALT diagnostic. The C-Circle biomarker is the only known ALT specific molecule and the C-Circle Assay the only quantitative ALT assay that is amenable to clinical use. We show here that C-Circles are secreted by ALT+ cancer cell lines inside the exosomes and are protected from nucleases. We also show that secreted C-Circles, like intracellular C-Circles, are an ALT-specific biomarker, and in high-risk neuroblastoma, the blood-based C-Circle Assay has the potential to be an accurate diagnostic for ALT cancer activity. Therefore, the secretion of C-Circles by ALT+ cancer cells in the exosomes provides a stable blood-based biomarker and, potentially, a clinical diagnostic for ALT activity, which is required for the development of ALT-targeted therapies as well as for the diagnosis and monitoring of ALT+ cancer. Abstract C-Circles, self-primed telomeric C-strand templates for rolling circle amplification, are the only known alternative-lengthening-of-telomeres (ALT)-specific molecule. However, little is known about the biology of C-Circles and if they may be clinically useful. Here we show that C-Circles are secreted by ALT+ cancer cells inside exosomes, and that a blood-based C-Circle Assay (CCA) can provide an accurate diagnostic for ALT activity. Extracellular vesicles were isolated by differential centrifugation from the growth media of lung adenocarcinoma, glioblastoma, neuroblastoma, osteosarcoma, and soft tissue sarcoma cell lines, and C-Circles were detected in the exosome fraction from all eleven ALT+ cancer cell lines and not in any extracellular fraction from the eight matching telomerase positive cancer cell lines or the normal fibroblast strain. The existence of C-Circles in ALT+ exosomes was confirmed with exosomes isolated by iodixanol gradient separation and CD81-immunoprecipitation, and C-Circles in the exosomes were protected from nucleases. On average, 0.4% of the total ALT+ intracellular C-Circles were secreted in the exosomes every 24 h. Comparing the serum-based and tumor-based CCAs in 35 high risk neuroblastoma patients divided randomly into ALT+ threshold derivation and validation groups, we found the serum-based CCA to have 100% sensitivity (6/6), 70% specificity (7/10), and 81% concordance (13/16). We conclude that the secretion of C-Circles by ALT+ cancer cells in the exosomes provides a stable blood-based biomarker and a potential clinical diagnostic for ALT activity.
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Affiliation(s)
- Yuan-Yin Chen
- Prince of Wales Clinical School, University of NSW, UNSW, Sydney 2052, Australia; (Y.-Y.C.); (Y.Z.); (R.L.); (N.M.L.R.)
| | - Rebecca Dagg
- Children’s Cancer Research Unit, The Children’s Hospital at Westmead, Faculty of Medicine and Health, University of Sydney, Westmead 2145, Australia; (R.D.); (L.M.S.L.)
| | - Yuchen Zhang
- Prince of Wales Clinical School, University of NSW, UNSW, Sydney 2052, Australia; (Y.-Y.C.); (Y.Z.); (R.L.); (N.M.L.R.)
| | - Joyce H. Y. Lee
- Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead 2145, Australia; (J.H.Y.L.); (R.R.R.)
| | - Robert Lu
- Prince of Wales Clinical School, University of NSW, UNSW, Sydney 2052, Australia; (Y.-Y.C.); (Y.Z.); (R.L.); (N.M.L.R.)
| | - Nancy Martin La Rotta
- Prince of Wales Clinical School, University of NSW, UNSW, Sydney 2052, Australia; (Y.-Y.C.); (Y.Z.); (R.L.); (N.M.L.R.)
| | - Sandra Sampl
- Comprehensive Cancer Center, Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, 1090 Vienna, Austria; (S.S.); (M.K.-D.); (K.H.)
| | - Medina Korkut-Demirbaş
- Comprehensive Cancer Center, Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, 1090 Vienna, Austria; (S.S.); (M.K.-D.); (K.H.)
| | - Klaus Holzmann
- Comprehensive Cancer Center, Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, 1090 Vienna, Austria; (S.S.); (M.K.-D.); (K.H.)
| | - Loretta M. S. Lau
- Children’s Cancer Research Unit, The Children’s Hospital at Westmead, Faculty of Medicine and Health, University of Sydney, Westmead 2145, Australia; (R.D.); (L.M.S.L.)
| | - Roger R. Reddel
- Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead 2145, Australia; (J.H.Y.L.); (R.R.R.)
| | - Jeremy D. Henson
- Prince of Wales Clinical School, University of NSW, UNSW, Sydney 2052, Australia; (Y.-Y.C.); (Y.Z.); (R.L.); (N.M.L.R.)
- Correspondence:
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Henson JD, Lau LM, Koch S, Martin La Rotta N, Dagg RA, Reddel RR. The C-Circle Assay for alternative-lengthening-of-telomeres activity. Methods 2016; 114:74-84. [PMID: 27595911 DOI: 10.1016/j.ymeth.2016.08.016] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/24/2016] [Accepted: 08/31/2016] [Indexed: 11/25/2022] Open
Abstract
The C-Circle Assay has satisfied the need for a rapid, robust and quantitative ALT assay that responds quickly to changes in ALT activity. The C-Circle Assay involves (i) extraction or simple preparation (Quick C-Circle Preparation) of the cell's DNA, which includes C-Circles (ii) amplification of the self-primed C-Circles with a rolling circle amplification reaction and (iii) sequence specific detection of the amplification products by native telomeric DNA dot blot or telomeric qPCR. Here we detail the protocols and considerations required to perform the C-Circle Assay and its controls, which include exonuclease removal of linear telomeric DNA, production of the synthetic C-Circle C96 and modulation of ALT activity by γ-irradiation.
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Affiliation(s)
- Jeremy D Henson
- Cancer Cell Immortality Group, Adult Cancer Program, Prince of Wales Clinical School, UNSW Australia, NSW, Australia.
| | - Loretta M Lau
- Cancer Research Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Sylvia Koch
- Cancer Cell Immortality Group, Adult Cancer Program, Prince of Wales Clinical School, UNSW Australia, NSW, Australia
| | - Nancy Martin La Rotta
- Cancer Cell Immortality Group, Adult Cancer Program, Prince of Wales Clinical School, UNSW Australia, NSW, Australia
| | - Rebecca A Dagg
- Children's Cancer Research Unit, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Roger R Reddel
- Cancer Research Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW, Australia
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Byrne JA, Chen Y, Martin La Rotta N, Peters GB. Challenges in identifying candidate amplification targets in human cancers: chromosome 8q21 as a case study. Genes Cancer 2012; 3:87-101. [PMID: 23050042 DOI: 10.1177/1947601912456287] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 07/08/2012] [Indexed: 12/13/2022] Open
Abstract
Detailed genomic characterization of cancer specimens is required to identify all genes whose dysregulation contributes to tumorigenesis and/or tumor progression. These include amplification target genes, whose oncogenic functions derive from their overexpression in response to increased gene copy number, and which increasingly serve as therapeutic targets and predictive markers. We propose that identifying novel amplification target genes is becoming more challenging, and may require the comparative analysis of multiple studies mapping gene copy number changes and/or defining associations between gene copy number and expression. We therefore reviewed the array comparative genomic hybridization and single nucleotide polymorphism profiling literature to identify copy number increases that were restricted to chromosome 8q21 in human cancers, which were reported most frequently in breast cancer. We determined the minimal regions of overlap between gained regions and then examined which chromosome 8q21 genes were most frequently overexpressed, or otherwise supported, in individual studies. As these combined approaches supported the previously proposed amplification targets TCEB1, TPD52, and WWP1, the comparison of multiple genomic studies may therefore effectively predict candidate gene amplification targets, and prioritize these for further study.
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Affiliation(s)
- Jennifer A Byrne
- Molecular Oncology Laboratory, Children's Cancer Research Unit, Kids Research Institute, The Children's Hospital at Westmead, Westmead, Australia ; The University of Sydney Discipline of Paediatrics and Child Health, The Children's Hospital at Westmead, Westmead, Australia
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