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Xu Y, Goldkorn A. Telomere and Telomerase Therapeutics in Cancer. Genes (Basel) 2016; 7:genes7060022. [PMID: 27240403 PMCID: PMC4929421 DOI: 10.3390/genes7060022] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 05/18/2016] [Accepted: 05/20/2016] [Indexed: 12/13/2022] Open
Abstract
Telomerase is a reverse transcriptase capable of utilizing an integrated RNA component as a template to add protective tandem telomeric single strand DNA repeats, TTAGGG, to the ends of chromosomes. Telomere dysfunction and telomerase reactivation are observed in approximately 90% of human cancers; hence, telomerase activation plays a unique role as a nearly universal step on the path to malignancy. In the past two decades, multiple telomerase targeting therapeutic strategies have been pursued, including direct telomerase inhibition, telomerase interference, hTERT or hTERC promoter driven therapy, telomere-based approaches, and telomerase vaccines. Many of these strategies have entered clinical development, and some have now advanced to phase III clinical trials. In the coming years, one or more of these new telomerase-targeting drugs may be expected to enter the pharmacopeia of standard care. Here, we briefly review the molecular functions of telomerase in cancer and provide an update about the preclinical and clinical development of telomerase targeting therapeutics.
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Affiliation(s)
- Yucheng Xu
- Division of Medical Oncology, Department of Medicine, Keck School of Medicine and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90033, USA.
| | - Amir Goldkorn
- Division of Medical Oncology, Department of Medicine, Keck School of Medicine and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90033, USA.
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Kim GA, Oh HJ, Kim MJ, Jo YK, Choi J, Kim JW, Lee TH, Lee BC. Effect of primary culture medium type for culture of canine fibroblasts on production of cloned dogs. Theriogenology 2015; 84:524-30. [DOI: 10.1016/j.theriogenology.2015.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/24/2015] [Accepted: 04/11/2015] [Indexed: 12/24/2022]
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Goldkorn A, Ely B, Tangen CM, Tai YC, Xu T, Li H, Twardowski P, Van Veldhuizen PJ, Agarwal N, Carducci MA, Monk JP, Garzotto M, Mack PC, Lara P, Higano CS, Hussain M, Vogelzang NJ, Thompson IM, Cote RJ, Quinn DI. Circulating tumor cell telomerase activity as a prognostic marker for overall survival in SWOG 0421: a phase III metastatic castration resistant prostate cancer trial. Int J Cancer 2015; 136:1856-62. [PMID: 25219358 PMCID: PMC4323674 DOI: 10.1002/ijc.29212] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/28/2014] [Accepted: 08/15/2014] [Indexed: 01/21/2023]
Abstract
Circulating tumor cells (CTC) are promising biomarkers in metastatic castration resistant prostate cancer (mCRPC), and telomerase activity (TA) is a recognized cancer marker. Therefore, we hypothesized that CTC TA may be prognostic of overall survival (OS) in mCRPC. To test this, we used a novel Parylene-C slot microfilter to measure live CTC TA in S0421, a phase III SWOG-led therapeutic trial. Blood samples underwent CTC capture and TA measurement by microfilter, as well as parallel enumeration by CellSearch (Janssen/J&J). Cox regression was used to assess baseline (pre-treatment) TA versus OS, and recursive partitioning was used to explore potential prognostic subgroups and to generate Kaplan-Meier (KM) OS curves. Samples were obtained from 263 patients and generated 215 TA measures. In patients with baseline CTC count ≥5 (47% of patients), higher CTC TA was associated with hazard ratio 1.14 (p = 0.001) for OS after adjusting for other clinical covariates including CTC counts and serum PSA at study entry. Recursive partitioning identified new candidate risk groups with KM OS curve separation based on CTC counts and TA. Notably, in men with an intermediate range baseline CTC count (6-54 CTCs/7.5 ml), low versus high CTC TA was associated with median survival of 19 versus 12 months, respectively (p = 0.009). Baseline telomerase activity from CTCs live-captured on a new slot microfilter is the first CTC-derived candidate biomarker prognostic of OS in a large patient subgroup in a prospective clinical trial. CTC telomerase activity thus merits further study and validation as a step towards molecular CTC-based precision cancer management.
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Affiliation(s)
- Amir Goldkorn
- University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA
| | | | | | - Yu-Chong Tai
- California Institute of Technology, Pasadena, CA
| | - Tong Xu
- University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA
| | - Hongli Li
- SWOG Statistical Center, Seattle, WA
| | | | | | - Neeraj Agarwal
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
| | | | | | - Mark Garzotto
- Portland Veterans Affairs Medical Center, Portland, OR
| | | | - Primo Lara
- University of California, Davis, Sacramento, CA
| | - Celestia S. Higano
- Puget Sound Oncology Consortium/Seattle Cancer Care Alliance/University of Washington, Seattle, WA
| | - Maha Hussain
- University of Michigan Comprehensive Cancer Center, Ann Arbor, MI
| | | | - Ian M. Thompson
- University of Texas Health Science Center at San Antonio, San Antonio, TX
| | | | - David I. Quinn
- University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA
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Bolton EM, Tuzova AV, Walsh AL, Lynch T, Perry AS. Noncoding RNAs in prostate cancer: the long and the short of it. Clin Cancer Res 2013; 20:35-43. [PMID: 24146262 DOI: 10.1158/1078-0432.ccr-13-1989] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
As the leading culprit in cancer incidence for American men, prostate cancer continues to pose significant diagnostic, prognostic, and therapeutic tribulations for clinicians. The vast spectrum of disease behavior warrants better molecular classification to facilitate the development of more robust biomarkers that can identify the more aggressive and clinically significant tumor subtypes that require treatment. The untranslated portion of the human transcriptome, namely noncoding RNAs (ncRNA), is emerging as a key player in cancer initiation and progression and boasts many attractive features for both biomarker and therapeutic research. Genetic linkage studies show that many ncRNAs are located in cancer-associated genomic regions that are frequently deleted or amplified in prostate cancer, whereas aberrant ncRNA expression patterns have well-established links with prostate tumor cell proliferation and survival. The dysregulation of pathways controlled by ncRNAs results in a cascade of multicellular events leading to carcinogenesis and tumor progression. The characterization of RNA species, their functions, and their clinical applicability is a major area of biologic and clinical importance. This review summarizes the growing body of evidence, supporting a pivotal role for ncRNAs in the pathogenesis of prostate cancer. We highlight the most promising ncRNA biomarkers for detection and risk stratification and present the state-of-play for RNA-based personalized medicine in treating the "untreatable" prostate tumors.
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Affiliation(s)
- Eva M Bolton
- Authors' Affiliations: Prostate Molecular Oncology, Trinity College Dublin; and Department of Urology, St. James's Hospital, Ireland
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He K, Xu T, Xu Y, Ring A, Kahn M, Goldkorn A. Cancer cells acquire a drug resistant, highly tumorigenic, cancer stem-like phenotype through modulation of the PI3K/Akt/β-catenin/CBP pathway. Int J Cancer 2013; 134:43-54. [DOI: 10.1002/ijc.28341] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 05/31/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Kaijie He
- Division of Medical Oncology; Department of Internal Medicine; University of Southern California Keck School of Medicine; Los Angeles; California
| | - Tong Xu
- Division of Medical Oncology; Department of Internal Medicine; University of Southern California Keck School of Medicine; Los Angeles; California
| | - Yucheng Xu
- Division of Medical Oncology; Department of Internal Medicine; University of Southern California Keck School of Medicine; Los Angeles; California
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Xu T, He K, Wang L, Goldkorn A. Prostate tumor cells with cancer progenitor properties have high telomerase activity and are rapidly killed by telomerase interference. Prostate 2011; 71:1390-400. [PMID: 21321978 PMCID: PMC3123672 DOI: 10.1002/pros.21355] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 01/14/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND Cancer progenitor cells (CPCs) have been postulated to promote treatment resistance and disease progression in prostate and other malignancies. We investigated whether the enzyme telomerase, which is active in cancer cells and in normal stem cells, plays an important role in CPC which can be exploited to neutralize these cells. METHODS We used flow cytometry and assays of gene expression, clonogenicity, and invasiveness to isolate and characterize a putative CPC subpopulation from freshly resected human prostatectomy specimens. Telomerase activity was measured by qPCR-based Telomeric Repeat Amplification Protocol (TRAP). Telomerase interference was achieved by ectopic expression of a mutated telomerase RNA construct which reprograms telomerase to generate "toxic" uncapped telomeres. Treated cells were assayed for apoptosis, proliferation in culture, and xenograft tumor formation. RESULTS CPC in prostate tumors expressed elevated levels of genes associated with a progenitor phenotype and were highly clonogenic and invasive. Significantly, CPC telomerase activity was 20- to 200-fold higher than in non-CPC from the same tumors, and CPC were exquisitely sensitive to telomerase interference which induced rapid apoptosis and growth inhibition. Similarly, induction of telomerase interference in highly tumorigenic CPC isolated from a prostate cancer cell line abrogated their ability to form tumor xenografts. CONCLUSIONS Human prostate tumors contain a CPC subpopulation with markedly elevated telomerase activity which renders them acutely susceptible to telomerase interference. These findings offer the first tumor-derived and in vivo evidence that telomerase may constitute a CPC "Achilles heel" which may ultimately form the basis for more effective new CPC-targeting therapies.
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Affiliation(s)
- Tong Xu
- Division of Medical Oncology, Department of Internal Medicine, University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA 90033
| | - Kaijie He
- Division of Medical Oncology, Department of Internal Medicine, University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA 90033
| | - Lina Wang
- Department of Pathology and Translational Pathology Core, University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA 90033
| | - Amir Goldkorn
- Division of Medical Oncology, Department of Internal Medicine, University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA 90033
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He K, Xu T, Goldkorn A. Cancer cells cyclically lose and regain drug-resistant highly tumorigenic features characteristic of a cancer stem-like phenotype. Mol Cancer Ther 2011; 10:938-48. [PMID: 21518726 DOI: 10.1158/1535-7163.mct-10-1120] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Drug resistance and brisk tumor initiation have traditionally been viewed as preexisting phenotypes present in small subpopulations of neoplastic cells sometimes termed cancer stem cells. However, recent work in cancer cell lines has shown that drug-resistant tumor-initiating features can emerge de novo within fractionated subpopulations of cells initially lacking these phenotypes. In the present study, we asked whether such phenotypic plasticity exists broadly in unperturbed cancer cell lines and tumor xenografts growing spontaneously without interventions such as drug selection or fractionation into subpopulations used in prior studies. To address this question, we used side population (SP) analysis combined with fluorescence labeling to identify a drug-resistant highly tumorigenic subpopulation and to track and analyze its interaction with the larger phenotypically negative population over time. Remarkably, we observed that SP size fluctuated in a cyclical manner: first contracting via differentiation into the non-SP (NSP) and then reexpanding via simultaneous direct conversion of numerous NSP cells back to the SP phenotype both in culture and in tumor xenografts. These findings show for the first time that adaptive, cancer-promoting traits such as drug resistance and brisk tumor initiation arise not only as solitary events under selective pressures but also as highly orchestrated transitions occurring concurrently in large numbers of cells even without specifically induced drug selection, ectopic gene expression, or fractionation into subpopulations. This high level of coordinated phenotypic plasticity bears consideration when using cancer cell lines as experimental models and may have significant implications for therapeutic efforts targeting cancer stem cells, which are marked by a drug-resistant tumor-initiating phenotype.
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Affiliation(s)
- Kaijie He
- Division of Medical Oncology, Department of Internal Medicine, University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Suite 3440, Los Angeles, CA 90033, USA
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Xu T, Lu B, Tai YC, Goldkorn A. A cancer detection platform which measures telomerase activity from live circulating tumor cells captured on a microfilter. Cancer Res 2010; 70:6420-6. [PMID: 20663903 DOI: 10.1158/0008-5472.can-10-0686] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Circulating tumor cells (CTC) quantified in cancer patients' blood can predict disease outcome and response to therapy. However, the CTC analysis platforms commonly used cannot capture live CTCs and only apply to tumors of epithelial origin. To address these limitations, we have developed a novel cancer detection platform which measures telomerase activity from live CTCs captured on a parylene-C slot microfilter. Using a constant low-pressure delivery system, the new microfilter platform was capable of cell capture from 1 mL of whole blood in less than 5 minutes, achieving 90% capture efficiency, 90% cell viability, and 200-fold sample enrichment. Importantly, the captured cells retained normal morphology by scanning electron microscopy and could be readily manipulated, further analyzed, or expanded on- or off-filter. Telomerase activity--a well-recognized universal cancer marker--was reliably detected by quantitative PCR from as few as 25 cancer cells added into 7.5 mL of whole blood and captured on the microfilter. Moreover, significant telomerase activity elevation was also measured from patients' blood samples and from single cancer cells lifted off of the microfilter. Live CTC capture and analysis is fast and simple yet highly quantitative, versatile, and applicable to nearly all solid tumor types, making this a highly promising new strategy for cancer detection and characterization.
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Affiliation(s)
- Tong Xu
- Division of Medical Oncology, Department of Internal Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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