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Abstract
Human pluripotent stem cells (PSC) acquire recurrent chromosomal instabilities during prolonged in vitro culture that threaten to preclude their use in cell-based regenerative medicine. The rapid proliferation of pluripotent cells leads to constitutive replication stress, hindering the progression of DNA replication forks and in some cases leading to replication-fork collapse. Failure to overcome replication stress can result in incomplete genome duplication, which, if left to persist into the subsequent mitosis, can result in structural and numerical chromosomal instability. We have recently applied the DNA fiber assay to the study of replication stress in human PSC and found that, in comparison to somatic cells states, these cells display features of DNA replication stress that include slower replication fork speeds, evidence of stalled forks, and replication initiation from dormant replication origins. These findings have expanded on previous work demonstrating that extensive DNA damage in human PSC is replication associated. In this capacity, the DNA fiber assay has enabled the development of an advanced nucleoside-enriched culture medium that increases replication fork progression and decreases DNA damage and mitotic errors in human PSC cultures. The DNA fiber assay allows for the study of replication fork dynamics at single-molecule resolution. The assay relies on cells incorporating nucleotide analogs into nascent DNA during replication, which are then measured to monitor several replication parameters. Here we provide an optimized protocol for the fiber assay intended for use with human PSC, and describe the methods employed to analyze replication fork parameters. © 2020 Wiley Periodicals LLC. Basic Protocol 1: DNA fiber labeling Basic Protocol 2: DNA fiber spreading Basic Protocol 3: Immunostaining Support Protocol 1: Microscopy/data acquisition Support Protocol 2: Data analysis.
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Affiliation(s)
- Jason A Halliwell
- The Centre for Stem Cell Biology, University of Sheffield, Department of Biomedical Science, Sheffield, United Kingdom
| | - Polly Gravells
- Academic Unit of Molecular Oncology, Sheffield Institute for Nucleic Acids (SInFoNiA), Department of Oncology and Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Helen E Bryant
- Academic Unit of Molecular Oncology, Sheffield Institute for Nucleic Acids (SInFoNiA), Department of Oncology and Metabolism, University of Sheffield, Sheffield, United Kingdom
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Kinsella T, Safran H, Wiersma S, DiPetrillo T, Schumacher A, Rosati K, Vatkevich J, Anderson LW, Hill KD, Kunos C, Collins JM. Phase I and Pharmacology Study of Ropidoxuridine (IPdR) as Prodrug for Iododeoxyuridine-Mediated Tumor Radiosensitization in Advanced GI Cancer Undergoing Radiation. Clin Cancer Res 2019; 25:6035-6043. [PMID: 31337643 PMCID: PMC6801071 DOI: 10.1158/1078-0432.ccr-19-0862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/21/2019] [Accepted: 07/17/2019] [Indexed: 12/30/2022]
Abstract
PURPOSE Iododeoxyuridine (IUdR) is a potent radiosensitizer; however, its clinical utility is limited by dose-limiting systemic toxicities and the need for prolonged continuous infusion. 5-Iodo-2-pyrimidinone-2'-deoxyribose (IPdR) is an oral prodrug of IUdR that, compared with IUdR, is easier to administer and less toxic, with a more favorable therapeutic index in preclinical studies. Here, we report the clinical and pharmacologic results of a first-in-human phase I dose escalation study of IPdR + concurrent radiation therapy (RT) in patients with advanced metastatic gastrointestinal (GI) cancers. PATIENTS AND METHODS Adult patients with metastatic GI cancers referred for palliative RT to the chest, abdomen, or pelvis were eligible for study. Patients received IPdR orally once every day × 28 days beginning 7 days before the initiation of RT (37.5 Gy in 2.5 Gy × 15 fractions). A 2-part dose escalation scheme was used, pharmacokinetic studies were performed at multiple time points, and all patients were assessed for toxicity and response to Day 56. RESULTS Nineteen patients were entered on study. Dose-limiting toxicity was encountered at 1,800 mg every day, and the recommended phase II dose is 1,200 mg every day. Pharmacokinetic analyses demonstrated achievable and sustainable levels of plasma IUdR ≥1 μmol/L (levels previously shown to mediate radiosensitization). Two complete, 3 partial, and 9 stable responses were achieved in target lesions. CONCLUSIONS Administration of IPdR orally every day × 28 days with RT is feasible and tolerable at doses that produce plasma IUdR levels ≥1 μmol/L. These results support the investigation of IPdR + RT in phase II studies.
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Affiliation(s)
- Timothy Kinsella
- Brown University Oncology Group (BrUOG), Providence, Rhode Island.
- EMEK, Inc., Warwick, Rhode Island
| | - Howard Safran
- Brown University Oncology Group (BrUOG), Providence, Rhode Island
| | | | | | | | - Kayla Rosati
- Brown University Oncology Group (BrUOG), Providence, Rhode Island
| | | | | | - Kimberly D Hill
- Leidos Biomedical Research Inc, Frederick National Laboratory for Cancer Research, Frederick, Maryland
| | - Charles Kunos
- Cancer Therapy Evaluation Program (CTEP), NCI, Bethesda, Maryland
| | - Jerry M Collins
- Developmental Therapeutics Program (DTP), NCI, Bethesda, Maryland
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Khoei S, Shoja M, Mostaar A, Faeghi F. Effects of resveratrol and methoxyamine on the radiosensitivity of iododeoxyuridine in U87MG glioblastoma cell line. Exp Biol Med (Maywood) 2016; 241:1229-36. [PMID: 26748400 DOI: 10.1177/1535370215622583] [Citation(s) in RCA: 10] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 11/18/2015] [Indexed: 11/15/2022] Open
Abstract
The purpose of this study was to evaluate the combination effect of resveratrol and methoxyamine on radiosensitivity of iododeoxyuridine in spheroid culture of U87MG glioblastoma cell line using colony formation and alkaline comet assays. Spheroids on day-20 with 350 µm diameters were treated with 20 µM resveratrol and/or 6 mM methoxyamine and/or 1 µM iododeoxyuridine for one volume doubling time (67 h), and then irradiated with 2 Gy gamma-radiation ((60)Co) in different groups. After treatment, viability of the cells, colony forming ability and DNA damages were obtained by blue dye exclusion, colony formation and alkaline comet assay, respectively. Our results showed that methoxyamine and resveratrol could significantly reduce colony number and induce the DNA damages of glioblastoma spheroid cells treated with iododeoxyuridine in combination with gamma-rays. Therefore, methoxyamine as base excision repair inhibitor and resveratrol as hypoxia inducible factor 1-alpha inhibitor in combination with iododeoxyuridine as radiosensitizer enhanced the radiosensitization of glioblastoma spheroid cells.
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Affiliation(s)
- Samideh Khoei
- Medical Physics Department, School of Medicine, Iran University of Medical Sciences, Tehran 1449614525, Iran Razi Drug Research Centre, Iran University of Medical Sciences, Tehran 1449614525, Iran
| | - Mohsen Shoja
- Radiology Technology Department, School of Paramedicine, Shahid Beheshti University of Medical Sciences, Tehran 1449614525, Iran
| | - Ahmad Mostaar
- Medical Physics and Medical Engineering Department, Shahid Beheshti University of Medical Sciences, Tehran 1449614525, Iran
| | - Fariborz Faeghi
- Radiology Technology Department, School of Paramedicine, Shahid Beheshti University of Medical Sciences, Tehran 1449614525, Iran
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Foti SB, Chou A, Moll AD, Roskams AJ. HDAC inhibitors dysregulate neural stem cell activity in the postnatal mouse brain. Int J Dev Neurosci 2013; 31:434-47. [PMID: 23542004 DOI: 10.1016/j.ijdevneu.2013.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [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: 09/19/2012] [Revised: 03/15/2013] [Accepted: 03/16/2013] [Indexed: 01/09/2023] Open
Abstract
The mammalian central nervous system (CNS) undergoes significant expansion postnatally, producing astrocytes, oligodendrocytes and inhibitory neurons to modulate the activity of neural circuits. This is coincident in humans with the emergence of pediatric epilepsy, a condition commonly treated with valproate/valproic acid (VPA), a potent inhibitor of histone deacetylases (HDACs). The sequential activity of specific HDACs, however, may be essential for the differentiation of distinct subpopulations of neurons and glia. Here, we show that different subsets of CNS neural stem cells (NSCs) and progenitors switch expression of HDAC1 and HDAC2 as they commit to a neurogenic lineage in the subventricular zone (SVZ) and dentate gyrus (DG). The administration of VPA for only one week from P7-P14, combined with sequential injections of thymidine analogs reveals that VPA stimulates a significant and differential decrease in the production and differentiation of progeny of NSCs in the DG, rostral migratory stream (RMS), and olfactory bulb (OB). Cross-fostering VPA-treated mice revealed, however, that a postnatal failure to thrive induced by VPA treatment had a greater effect on DG neurogenesis than VPA action directly. By one month after VPA, OB interneuron genesis was significantly and differentially reduced in both periglomerular and granule neurons. Using neurosphere assays to test if VPA directly regulates NSC activity, we found that short term treatment with VPA in vivo reduced neurosphere numbers and size, a phenotype that was also obtained in neurospheres from control mice treated with VPA and an alternative HDAC inhibitor, Trichostatin A (TSA) at 0 and 3 days in vitro (DIV). Collectively, these data show that clinically used HDAC inhibitors like VPA and TSA can perturb postnatal neurogenesis; and their use should be carefully considered, especially in individuals whose brains are actively undergoing key postnatal time windows of development.
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Affiliation(s)
- Stacey Beth Foti
- Department of Zoology, Life Sciences Institute and Brain Research Centre, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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Abstract
A more flexible and higher-yielding in vitro DNA mismatch repair (MMR) substrate construction method, which was developed initially by Wang and Hays, is described for the construction of a nucleotide-based chemical mismatch (G/IU) and a G/T mismatch. Our modifications use the combination of two endonuclease enzymes (NheI and BciVI) and two new redesigned plasmids (pWDAH1A and pWDSH1B). In our modified methodology, plasmids are initially digested with the nicking endonucleases, followed by the streptavidin treatment. The mismatch-containing oligo is then annealed to the gap DNA and finally ligated to produce a mismatch-containing DNA substrate. We report a high efficiency (up to 90%) of these mismatch substrates and confirm recognition using a functional assay. These modifications, coupled with the use of the redesigned plasmids, can be applied for the construction of other types of chemically induced mismatches as well as insertion-deletion loops for future in vitro studies of MMR processing by our group and others.
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Affiliation(s)
- Weinan Du
- Department of Radiation Oncology, Case Integrative Cancer Biology Program, Case Western Reserve University Cleveland, OH, USA
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Kinsella TJ, Gurkan-Cavusoglu E, Du W, Loparo KA. Integration of Principles of Systems Biology and Radiation Biology: Toward Development of in silico Models to Optimize IUdR-Mediated Radiosensitization of DNA Mismatch Repair Deficient (Damage Tolerant) Human Cancers. Front Oncol 2011; 1:20. [PMID: 22649757 PMCID: PMC3355906 DOI: 10.3389/fonc.2011.00020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/12/2011] [Indexed: 11/16/2022] Open
Abstract
Over the last 7 years, we have focused our experimental and computational research efforts on improving our understanding of the biochemical, molecular, and cellular processing of iododeoxyuridine (IUdR) and ionizing radiation (IR) induced DNA base damage by DNA mismatch repair (MMR). These coordinated research efforts, sponsored by the National Cancer Institute Integrative Cancer Biology Program (ICBP), brought together system scientists with expertise in engineering, mathematics, and complex systems theory and translational cancer researchers with expertise in radiation biology. Our overall goal was to begin to develop computational models of IUdR- and/or IR-induced base damage processing by MMR that may provide new clinical strategies to optimize IUdR-mediated radiosensitization in MMR deficient (MMR−) “damage tolerant” human cancers. Using multiple scales of experimental testing, ranging from purified protein systems to in vitro (cellular) and to in vivo (human tumor xenografts in athymic mice) models, we have begun to integrate and interpolate these experimental data with hybrid stochastic biochemical models of MMR damage processing and probabilistic cell cycle regulation models through a systems biology approach. In this article, we highlight the results and current status of our integration of radiation biology approaches and computational modeling to enhance IUdR-mediated radiosensitization in MMR− damage tolerant cancers.
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Affiliation(s)
- Timothy J Kinsella
- Department of Radiation Oncology, Warren Alpert Medical School of Brown University and Rhode Island Hospital Providence, RI, USA
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Neti PVSV, Howell RW. Isolating effects of microscopic nonuniform distributions of (131)I on labeled and unlabeled cells. J Nucl Med 2004; 45:1050-8. [PMID: 15181140 PMCID: PMC2911233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
UNLABELLED Radiopharmaceuticals are generally distributed nonuniformly in tissue. At the microscopic level, only a fraction of the cells in tissue are labeled. Consequently, the labeled cells receive an absorbed dose from radioactivity within the cell (self-dose) as well as an absorbed dose from radioactivity in surrounding cells (cross-dose). On the other hand, unlabeled cells only receive a cross-dose. This work uses a novel approach to examine the lethal effects of microscopic nonuniformities of (131)I individually on the labeled and unlabeled cells. METHODS A multicellular tissue model was used to investigate the lethality of microscopic nonuniform distributions of (131)I. Mammalian cells (V79) were dyed with CFDA-SE (carboxy fluorescein diacetate succinimidyl ester) and labeled with (131)I-iododeoxyuridine ((131)IdU). The dyed labeled cells were then mixed with equal numbers of unlabeled cells, and 3-dimensional tissue constructs (4 x 10(6) cells) were formed by centrifugation in a small tube. This resulted in a uniform distribution of (131)I at the macroscopic level but nonuniform distribution at the multicellular level, wherein 50% of the cells were labeled. The multicellular clusters were maintained at 10.5 degrees C for 72 h to allow (131)I decays to accumulate. The clusters were then dismantled and the labeled (dyed) and unlabeled (undyed) cells were separately seeded for colony formation using a fluorescence-activated cell sorter. RESULTS The unlabeled cells, which received only a cross-dose, exhibited a mean lethal dose D(37) of 4.0 +/- 0.3 Gy. In contrast, the labeled cells received both a self-dose and a cross-dose. Isolating the effects of the self-dose resulted in a D(37) of 1.2 +/- 0.3 Gy, which was about 3.3 times more toxic per unit dose than the cross-dose. The reason for these differences appears to be primarily related to the higher relative biological effectiveness of the self-dose delivered by (131)IdU compared with the cross-dose. Theoretical modeling of the killing of labeled and unlabeled cells was achieved by considering the cellular self-doses and cross-doses. CONCLUSION Cellular self-doses and cross-doses play an important role in determining the biological response of tissue to microscopic nonuniform distributions of (131)I. Prediction of the biological response requires that both self-doses and cross-doses be considered along with their relative lethality per unit dose.
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Affiliation(s)
- Prasad V S V Neti
- Department of Radiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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Neti PVSV, Howell RW. When may a nonuniform distribution of 131I be considered uniform? An experimental basis for multicellular dosimetry. J Nucl Med 2003; 44:2019-26. [PMID: 14660728 PMCID: PMC2933742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
UNLABELLED To varying degrees, radiopharmaceuticals are distributed nonuniformly in tissue. At a macroscopic level, the radiopharmaceutical may appear to be uniformly distributed throughout the tissue. However, on closer inspection, not all cells in the tissue may be labeled with the radiopharmaceutical. Furthermore, the radioactivity in the cells may be localized only in certain compartments within the cell. This work uses a cell culture model to examine the impact of nonuniformity at the multicellular level on the lethal effects of (131)I. METHODS A 3-dimensional tissue culture model was used to investigate the biologic effects of nonuniform distributions of (131)I in a large population of mammalian cells. Chinese hamster V79 cells were labeled with (131)I-iododeoxyuridine ((131)IdU), mixed with unlabeled cells, and multicellular clusters (4 x 10(6) cells) were formed by gentle centrifugation. Thus, the labeled cells were randomly located in the cluster to achieve a uniform distribution of radioactivity at the macroscopic level, yet nonuniform at the multicellular level. The clusters were assembled as described and then maintained at 10.5 degrees C for 72 h to allow (131)I decays to accumulate. The clusters were then dismantled and the cells were plated for colony formation. RESULTS When 100% of the cells were labeled, the surviving fraction of cells in the cluster was exponentially dependent on the cluster activity down to 0.1% survival. In contrast, when 10% of the cells were labeled, it was observed that the survival fraction begins to saturate at about 1% survival. Absorbed-dose estimates reveal that the mean lethal cluster dose is 4.5, 5.7, and 6.4 Gy for 100%, 10%, and 1% labeling, respectively. CONCLUSION These data indicate that when the distribution of (131)I is uniform at the macroscopic level, but nonuniform at the multicellular level, the mean absorbed dose to a tissue element may not be a suitable quantity for use in predicting biologic effect. Rather, cellular and multicellular dosimetry approaches may be necessary to predict the biologic effects of incorporated (131)I.
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Affiliation(s)
- Prasad V S V Neti
- Division of Radiation Research, Department of Radiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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