28 results on '"Bret R. Adams"'
Search Results
2. Supplementary Table 1 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 58K, Concentrations of KU-60019 in mouse brain after CED.
- Published
- 2023
3. Supplementary Figure 1 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF File - 571K, Human U1242 glioma cells form highly invasive and aggressive orthotopic tumors in mice.
- Published
- 2023
4. Supplementary Figure 8 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 159K, U1242 tumors with 'forced' expression of mutant p53 are more sensitive to KU-60019.
- Published
- 2023
5. Supplementary Figure 3 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF File - 49K, Imaging of tumors that were apparently cured.
- Published
- 2023
6. Supplementary Figure Legend from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 82K
- Published
- 2023
7. Supplementary Figure 7 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 80K, Imaging of U87/luc-DsRed (p53-281G) bearing mice.
- Published
- 2023
8. Supplementary Figure 4 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF File - 80K, KU-60019 administered by CED radiosensitizes U1242 tumors.
- Published
- 2023
9. Supplementary Figure 5 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF File - 578K, Human U1242/luc-GFP gliomas show dose-dependent increases in p-(S824)-KAP1 foci formation after radiation which can be inhibited by KU-60019.
- Published
- 2023
10. Supplementary Table 3 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 45K, Preparation of calibration and QC solutions.
- Published
- 2023
11. Supplementary Table 4 from ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Kristoffer Valerie, Nitai D. Mukhopadhyay, Sang Kyun Lim, Luis F. Parada, Kevin S. Choe, Mark J. O'Connor, Alan Lau, David G. Temesi, Sumitra Deb, Sarah E. Golding, Donna Gilfor, Ashraf Khalil, Alison F. Wagner, Bret R. Adams, Mary Tokarz, Nicholas C.K. Valerie, Jason M. Beckta, Elizabeth Rosenberg, Muhammad Sajjad, and Laura Biddlestone-Thorpe
- Abstract
PDF file - 53K, Preparation of calibration and QC tissue matrix.
- Published
- 2023
12. Dynamic dependence on ATR and ATM for double-strand break repair in human embryonic stem cells and neural descendants.
- Author
-
Bret R Adams, Sarah E Golding, Raj R Rao, and Kristoffer Valerie
- Subjects
Medicine ,Science - Abstract
The DNA double-strand break (DSB) is the most toxic form of DNA damage. Studies aimed at characterizing DNA repair during development suggest that homologous recombination repair (HRR) is more critical in pluripotent cells compared to differentiated somatic cells in which nonhomologous end joining (NHEJ) is dominant. We have characterized the DNA damage response (DDR) and quality of DNA double-strand break (DSB) repair in human embryonic stem cells (hESCs), and in vitro-derived neural cells. Resolution of ionizing radiation-induced foci (IRIF) was used as a surrogate for DSB repair. The resolution of gamma-H2AX foci occurred at a slower rate in hESCs compared to neural progenitors (NPs) and astrocytes perhaps reflective of more complex DSB repair in hESCs. In addition, the resolution of RAD51 foci, indicative of active homologous recombination repair (HRR), showed that hESCs as well as NPs have high capacity for HRR, whereas astrocytes do not. Importantly, the ATM kinase was shown to be critical for foci formation in astrocytes, but not in hESCs, suggesting that the DDR is different in these cells. Blocking the ATM kinase in astrocytes not only prevented the formation but also completely disassembled preformed repair foci. The ability of hESCs to form IRIF was abrogated with caffeine and siRNAs targeted against ATR, implicating that hESCs rely on ATR, rather than ATM for regulating DSB repair. This relationship dynamically changed as cells differentiated. Interestingly, while the inhibition of the DNA-PKcs kinase (and presumably non-homologous endjoining [NHEJ]) in astrocytes slowed IRIF resolution it did not in hESCs, suggesting that repair in hESCs does not utilize DNA-PKcs. Altogether, our results show that hESCs have efficient DSB repair that is largely ATR-dependent HRR, whereas astrocytes critically depend on ATM for NHEJ, which, in part, is DNA-PKcs-independent.
- Published
- 2010
- Full Text
- View/download PDF
13. DNA Damage Response in Human Stem Cells and Neural Descendants
- Author
-
Jason M, Beckta, Bret R, Adams, and Kristoffer, Valerie
- Subjects
DNA Repair ,Stem Cells ,Humans ,DNA Breaks, Double-Stranded ,Ataxia Telangiectasia Mutated Proteins ,Embryonic Stem Cells ,DNA Damage - Abstract
Glial cells are crucial for the normal function of neurons and are intricately involved in the pathogenesis of neurodegenerative diseases as well as neurologic malignancies. A deeper understanding of the mechanisms by which glial cells influence the development of such pathologies will undoubtedly lead to new and improved therapeutic approaches. Commercially available human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), both of which can be differentiated into neural progenitors (NPs) and various neural cell lineages, have become widely used as sources for producing normal human central nervous system (CNS) cells. A better understanding of the DNA damage response (DDR) that occurs in these cells after therapeutic ionizing radiation (IR) and chemotherapy is essential for assessing the effects on healthy human brain.Neurodegenerative features associated with conditions such as ataxia telangiectasia and Nijmegen breakage syndrome highlight the importance of DNA double strand break (DSB) repair pathways in maintaining genomic integrity in cells of the CNS. Similarly, the development of brain tumors is also intricately linked to DNA repair. The importance of ATM and the other phosphatidylinositol 3-kinase-related kinase (PIKK) family members, ATR and DNA-PKcs, is not fully defined in either CNS developmental or pathological states. While their roles are relatively well established in the DDR of proliferating cells, our recent work has demonstrated that these processes exhibit spatiotemporal evolution during cell differentiation. This chapter discusses and explores various laboratory techniques for investigating the role of ATM in hESCs and differentiated neural cells.
- Published
- 2017
14. DNA Damage Response in Human Stem Cells and Neural Descendants
- Author
-
Bret R. Adams, Jason M. Beckta, and Kristoffer Valerie
- Subjects
0301 basic medicine ,DNA repair ,Cellular differentiation ,Biology ,medicine.disease ,Embryonic stem cell ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,Ataxia-telangiectasia ,medicine ,Progenitor cell ,Stem cell ,Induced pluripotent stem cell ,Nijmegen breakage syndrome - Abstract
Glial cells are crucial for the normal function of neurons and are intricately involved in the pathogenesis of neurodegenerative diseases as well as neurologic malignancies. A deeper understanding of the mechanisms by which glial cells influence the development of such pathologies will undoubtedly lead to new and improved therapeutic approaches. Commercially available human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), both of which can be differentiated into neural progenitors (NPs) and various neural cell lineages, have become widely used as sources for producing normal human central nervous system (CNS) cells. A better understanding of the DNA damage response (DDR) that occurs in these cells after therapeutic ionizing radiation (IR) and chemotherapy is essential for assessing the effects on healthy human brain.Neurodegenerative features associated with conditions such as ataxia telangiectasia and Nijmegen breakage syndrome highlight the importance of DNA double strand break (DSB) repair pathways in maintaining genomic integrity in cells of the CNS. Similarly, the development of brain tumors is also intricately linked to DNA repair. The importance of ATM and the other phosphatidylinositol 3-kinase-related kinase (PIKK) family members, ATR and DNA-PKcs, is not fully defined in either CNS developmental or pathological states. While their roles are relatively well established in the DDR of proliferating cells, our recent work has demonstrated that these processes exhibit spatiotemporal evolution during cell differentiation. This chapter discusses and explores various laboratory techniques for investigating the role of ATM in hESCs and differentiated neural cells.
- Published
- 2017
15. ATM Kinase Inhibition Preferentially Sensitizes p53-Mutant Glioma to Ionizing Radiation
- Author
-
Elizabeth Rosenberg, Luis F. Parada, Sumitra Deb, Alan Lau, Mary E. Tokarz, David G. Temesi, Sang Kyun Lim, Muhammad Sajjad, Laura Biddlestone-Thorpe, Kristoffer Valerie, Nicholas C.K. Valerie, Donna Gilfor, Sarah E. Golding, Jason M. Beckta, Nitai D. Mukhopadhyay, Alison F. Wagner, Kevin S. Choe, Bret R. Adams, Mark J. O'Connor, and Ashraf Khalil
- Subjects
Cancer Research ,Radiosensitizer ,Pathology ,medicine.medical_specialty ,DNA damage ,Morpholines ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Radiation Tolerance ,Article ,Mice ,In vivo ,Cell Line, Tumor ,Radiation, Ionizing ,Radioresistance ,Glioma ,Adjuvant therapy ,medicine ,Animals ,Humans ,Brain Neoplasms ,Cancer ,Flow Cytometry ,medicine.disease ,Gene Expression Regulation, Neoplastic ,Oncology ,Cell culture ,Mutation ,Thioxanthenes ,Cancer research ,Tumor Suppressor Protein p53 - Abstract
Purpose: Glioblastoma multiforme (GBM) is the most lethal form of brain cancer with a median survival of only 12 to 15 months. Current standard treatment consists of surgery followed by chemoradiation. The poor survival of patients with GBM is due to aggressive tumor invasiveness, an inability to remove all tumor tissue, and an innate tumor chemo- and radioresistance. Ataxia–telangiectasia mutated (ATM) is an excellent target for radiosensitizing GBM because of its critical role in regulating the DNA damage response and p53, among other cellular processes. As a first step toward this goal, we recently showed that the novel ATM kinase inhibitor KU-60019 reduced migration, invasion, and growth, and potently radiosensitized human glioma cells in vitro. Experimental Design: Using orthotopic xenograft models of GBM, we now show that KU-60019 is also an effective radiosensitizer in vivo. Human glioma cells expressing reporter genes for monitoring tumor growth and dispersal were grown intracranially, and KU-60019 was administered intratumorally by convection-enhanced delivery or osmotic pump. Results: Our results show that the combined effect of KU-60019 and radiation significantly increased survival of mice 2- to 3-fold over controls. Importantly, we show that glioma with mutant p53 is much more sensitive to KU-60019 radiosensitization than genetically matched wild-type glioma. Conclusions: Taken together, our results suggest that an ATM kinase inhibitor may be an effective radiosensitizer and adjuvant therapy for patients with mutant p53 brain cancers. Clin Cancer Res; 19(12); 3189–200. ©2013 AACR.
- Published
- 2013
16. Pro-survival AKT and ERK signaling from EGFR and mutant EGFRvIII enhances DNA double-strand break repair in human glioma cells
- Author
-
Lawrence F. Povirk, Kristoffer Valerie, Amy J. Hawkins, Rhiannon N. Morgan, Sarah E. Golding, and Bret R. Adams
- Subjects
MAPK/ERK pathway ,Cancer Research ,DNA Repair ,DNA repair ,Blotting, Western ,RAD51 ,Article ,Histones ,Radioresistance ,Tumor Cells, Cultured ,Humans ,DNA Breaks, Double-Stranded ,Epidermal growth factor receptor ,Protein kinase B ,Mitogen-Activated Protein Kinase 1 ,Pharmacology ,Mitogen-Activated Protein Kinase 3 ,biology ,Brain Neoplasms ,Glioma ,Molecular biology ,Double Strand Break Repair ,ErbB Receptors ,enzymes and coenzymes (carbohydrates) ,Oncology ,Mutation ,Cancer research ,biology.protein ,Molecular Medicine ,Signal transduction ,Proto-Oncogene Proteins c-akt ,Signal Transduction - Abstract
The epidermal growth factor receptor (EGFR) is frequently dysregulated in malignant glioma that leads to increased resistance to cancer therapy. Upregulation of wild type or expression of mutant EGFR is associated with tumor radioresistance and poor clinical outcome. EGFR variant III (EGFRvIII) is the most common EGFR mutation in malignant glioma. Radioresistance is thought to be, at least in part, the result of a strong cytoprotective response fueled by signaling via AKT and ERK that is heightened by radiation in the clinical dose range. Several groups including ours have shown that this response may modulate DNA repair. Herein, we show that expression of EGFRvIII promoted gamma-H2AX foci resolution, a surrogate for double-strand break (DSB) repair, and thus enhanced DNA repair. Conversely, small molecule inhibitors targeting EGFR, MEK, and the expression of dominant-negative EGFR (EGFR-CD533) significantly reduced the resolution of gamma-H2AX foci. When homologous recombination repair (HRR) and non-homologous end joining (NHEJ) were specifically examined, we found that EGFRvIII stimulated and CD533 compromised HRR and NHEJ, respectively. Furthermore, NHEJ was blocked by inhibitors of AKT and ERK signaling pathways. Moreover, expression of EGFRvIII and CD533 increased and reduced, respectively, the formation of phospho-DNA-PKcs and -ATM repair foci, and RAD51 foci and expression levels, indicating that DSB repair is regulated at multiple levels. Altogether, signaling from EGFR and EGFRvIII promotes both HRR and NHEJ that is likely a contributing factor towards the radioresistance of malignant gliomas.
- Published
- 2009
17. The application of vinylogous iminium salt derivatives to an efficient relay synthesis of the pyrrole containing alkaloids polycitone A and B
- Author
-
Bret R. Adams, Robert B. Miller, Daniel W. Callahan, Nicholas E. Lauerman, Karen X. Du, Edith J. Banner, James A. Sikorski, John T. Gupton, Stuart C. Clough, Keith Krumpe, Kartik M. Keertikar, Barrett A. Little, John M. Solano, Austin B. Scharf, and Rene P.F. Kanters
- Subjects
chemistry.chemical_classification ,Organic Chemistry ,Salt (chemistry) ,Iminium ,Regioselectivity ,Biochemistry ,law.invention ,Electrophilic substitution ,chemistry.chemical_compound ,chemistry ,Suzuki reaction ,Relay ,law ,Drug Discovery ,Organic chemistry ,Pyrrole - Abstract
A new and efficient relay synthesis of the marine natural products polycitone A and B is described. The new strategy relies on the formation of 2,4-disubstituted pyrroles from a vinamidinium salt followed by electrophilic substitution at the 5-position of the pyrrole and Suzuki coupling at the 4-position to produce the tetrasubstituted heterocycle efficiently and with complete control of regiochemistry.
- Published
- 2005
18. Impact of Adjuvant Therapy on Patient Survival in Stage I/II High-Risk Endometrial Cancers
- Author
-
Aaron H. Wolfson, J. De La Garza, Lorraine Portelance, Brian M. Slomovitz, Isildinha M. Reis, J. Kodiyan, Bret R. Adams, Matthew J. Pearson, and W. Nieves-Neira
- Subjects
Oncology ,Cancer Research ,medicine.medical_specialty ,Radiation ,business.industry ,Internal medicine ,medicine ,Adjuvant therapy ,Radiology, Nuclear Medicine and imaging ,Patient survival ,business ,Stage i ii - Published
- 2015
19. Mode of action of pulegone on the urinary bladder of F344 rats
- Author
-
T. B. Adams, Mitscheli Sanches da Rocha, Sean V. Taylor, Puttappa R. Dodmane, Karen L. Pennington, Bret R. Adams, Samuel M. Cohen, Muhammad M. Anwar, Clint Wermes, and Lora L. Arnold
- Subjects
Menthofuran ,Metabolite ,Urinary Bladder ,Urine ,Cyclohexane Monoterpenes ,Pharmacology ,Toxicology ,chemistry.chemical_compound ,Oral administration ,Animals ,Humans ,Cells, Cultured ,Cell Proliferation ,Dose-Response Relationship, Drug ,Chemistry ,Body Weight ,Menthone ,Immunohistochemistry ,Rats, Inbred F344 ,Rats ,Cell Transformation, Neoplastic ,Biochemistry ,Bromodeoxyuridine ,Microscopy, Electron, Scanning ,Monoterpenes ,Female ,Pulegone ,Pennyroyal ,Piperitone - Abstract
Essential oils from mint plants, including peppermint and pennyroyal oils, are used at low levels as flavoring agents in various foods and beverages. Pulegone is a component of these oils. In a 2-year bioassay, oral administration of pulegone slightly increased the urothelial tumor incidence in female rats. We hypothesized that its mode of action (MOA) involved urothelial cytotoxicity and increased cell proliferation, ultimately leading to tumors. Pulegone was administered by gavage at 0, 75, or 150 mg/kg body weight to female rats for 4 and 6 weeks. Fresh void urine and 18-h urine were collected for crystal and metabolite analyses. Urinary bladders were evaluated by light microscopy and scanning electron microscopy (SEM) and bromodeoxyuridine (BrdU) labeling index. Pulegone and its metabolites, piperitenone, piperitone, menthofuran, and menthone, were tested for cytotoxicity in rat (MYP3) and human (1T1) urothelial cells by the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. No abnormal urinary crystals were observed by light microscopy. Urine samples (18-h) showed the presence of pulegone, piperitone, piperitenone, and menthofuran in both treated groups. By SEM, bladders from treated rats showed superficial necrosis and exfoliation. There was a significant increase in the BrdU labeling index in the high-dose group. In vitro studies indicated that pulegone and its metabolites, especially piperitenone, are excreted and concentrated in the urine at cytotoxic levels when pulegone is administered at high doses to female rats. The present study supports the hypothesis that cytotoxicity followed by regenerative cell proliferation is the MOA for pulegone-induced urothelial tumors in female rats.
- Published
- 2012
20. Dynamic inhibition of ATM kinase provides a strategy for glioblastoma multiforme radiosensitization and growth control
- Author
-
Sarah E. Golding, Kristoffer Valerie, Jason M. Beckta, Bret R. Adams, Mark J. O'Connor, Elizabeth Rosenberg, and Shayalini Wignarajah
- Subjects
Radiation-Sensitizing Agents ,DNA Repair ,DNA repair ,Cell Survival ,Morpholines ,Cell Cycle Proteins ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Protein Serine-Threonine Kinases ,Tripartite Motif-Containing Protein 28 ,Radiation Tolerance ,Histones ,chemistry.chemical_compound ,Glioma ,Radioresistance ,Cell Line, Tumor ,Report ,medicine ,Temozolomide ,Humans ,Phosphorylation ,Molecular Biology ,Protein kinase B ,Protein Kinase Inhibitors ,Tumor Suppressor Proteins ,Cell Biology ,medicine.disease ,Coculture Techniques ,DNA-Binding Proteins ,Dacarbazine ,Enzyme Activation ,Repressor Proteins ,Cell killing ,chemistry ,Cell culture ,Astrocytes ,Thioxanthenes ,Cancer research ,Growth inhibition ,Glioblastoma ,Developmental Biology ,medicine.drug ,DNA Damage - Abstract
Glioblastoma multiforme (GBM) is notoriously resistant to treatment. Therefore, new treatment strategies are urgently needed. ATM elicits the DNA damage response (DDR), which confers cellular radioresistance; thus, targeting the DDR with an ATM inhibitior (ATMi) is very attractive. Herein, we show that dynamic ATM kinase inhibition in the nanomolar range results in potent radiosensitization of human glioma cells, inhibits growth and does not conflict with temozolomide (TMZ) treatment. The second generation ATMi analog KU-60019 provided quick, reversible and complete inhibition of the DDR at sub-micromolar concentrations in human glioblastoma cells. KU-60019 inhibited the phosphorylation of the major DNA damage effectors p53, H2AX and KAP1 as well as AKT. Colony-forming radiosurvival showed that continuous exposure to nanomolar concentrations of KU-60019 effectively radiosensitized glioblastoma cell lines. When cells were co-treated with KU-60019 and TMZ, a slight increase in radiation-induced cell killing was noted, although TMZ alone was unable to radiosensitize these cells. In addition, without radiation, KU-60019 with or without TMZ reduced glioma cell growth but had no significant effect on the survival of human embryonic stem cell (hESC)-derived astrocytes. Altogether, transient inhibition of the ATM kinase provides a promising strategy for radiosensitizing GBM in combination with standard treatment. In addition, without radiation, KU-60019 limits growth of glioma cells in co-culture with human astrocytes that seem unaffected by the same treatment. Thus, inter-fraction growth inhibition could perhaps be achieved in vivo with minor adverse effects to the brain.
- Published
- 2012
21. Can Stereotactic Ablative Radiation Therapy (SABR) Improve Patient Selection for Lung Cancer Surgery and Reduce Perioperative Mortality?
- Author
-
Michael G. Chang, S. Szentpetery, Bret R. Adams, D. Moghanaki, L. Rogers, and N. Serrano
- Subjects
Cancer Research ,medicine.medical_specialty ,Lung cancer surgery ,Radiation ,business.industry ,medicine.medical_treatment ,Perioperative ,SABR volatility model ,Surgery ,Radiation therapy ,Oncology ,Ablative case ,medicine ,Radiology, Nuclear Medicine and imaging ,business ,Selection (genetic algorithm) - Published
- 2015
22. ATM-dependent ERK signaling via AKT in response to DNA double-strand breaks
- Author
-
Rhiannon N. Morgan, Lawrence F. Povirk, Elizabeth Rosenberg, Sarah E. Golding, Seth M. Dever, Kristoffer Valerie, Bret R. Adams, and Ashraf Khalil
- Subjects
MAPK/ERK pathway ,DNA Repair ,DNA repair ,MAP Kinase Signaling System ,Ultraviolet Rays ,Cell Cycle Proteins ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Protein Serine-Threonine Kinases ,Dephosphorylation ,chemistry.chemical_compound ,Report ,Humans ,DNA Breaks, Double-Stranded ,Phosphorylation ,Molecular Biology ,Protein kinase B ,Cells, Cultured ,Photolysis ,Tumor Suppressor Proteins ,Cell Biology ,Transfection ,Molecular biology ,DNA-Binding Proteins ,chemistry ,Bromodeoxyuridine ,Signal transduction ,Developmental Biology - Abstract
Ionizing radiation (IR) triggers many signaling pathways primarily originating from either damaged DNA or non-nuclear sources such as growth factor receptors. Thus, to study the DNA damage-induced signaling component alone by irradiation would be a challenge. To generate DNA double-strand breaks (DSBs) and minimize non-nuclear signaling, human cancer cells having bromodeoxyuridine (BrdU) - substituted DNA were treated with the photosensitizer Hoechst 33258 followed by long wavelength UV (UV-A) treatment (BrdU photolysis). BrdU photolysis resulted in well-controlled, dose- dependent generation of DSBs equivalent to radiation doses between 0.2 - 20 Gy, as determined by pulsed-field gel electrophoresis, and accompanied by dose-dependent ATM (ser-1981), H2AX (ser-139), Chk2 (thr-68), and p53 (ser-15) phosphorylation. Interestingly, low levels (≤ 2 Gy equivalents) of BrdU photolysis stimulated ERK phosphorylation whereas higher (> 2 Gy eq.) resulted in ERK dephosphorylation. ERK phosphorylation was ATM-dependent whereas dephosphorylation was ATM-independent. The ATM-dependent increase in ERK phosphorylation was also seen when DSBs were generated by transfection of cells with an EcoRI expression plasmid or by electroporation of EcoRI enzyme. Furthermore, AKT was critical for transmitting the DSB signal to ERK. Altogether, our results show that low levels of DSBs trigger ATM- and AKT-dependent ERK pro-survival signaling and increased cell proliferation whereas higher levels result in ERK dephosphorylation consistent with a dose-dependent switch from pro-survival to anti-survival signaling.
- Published
- 2011
23. ATM-independent, high-fidelity nonhomologous end joining predominates in human embryonic stem cells
- Author
-
Bret R. Adams, Kristoffer Valerie, Lawrence F. Povirk, and Amy J. Hawkins
- Subjects
Aging ,DNA Repair ,DNA repair ,Cellular differentiation ,Poly ADP ribose polymerase ,Molecular Sequence Data ,Cell Cycle Proteins ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Protein Serine-Threonine Kinases ,DSB repair ,03 medical and health sciences ,0302 clinical medicine ,KU-57788 ,BG01V ,Humans ,Cells, Cultured ,Embryonic Stem Cells ,Protein Kinase C ,030304 developmental biology ,0303 health sciences ,Gene knockdown ,Base Sequence ,Tumor Suppressor Proteins ,fungi ,Cell Differentiation ,Cell Biology ,DNA ,DNA repair protein XRCC4 ,equipment and supplies ,Embryonic stem cell ,Molecular biology ,Cell biology ,Non-homologous end joining ,DNA-Binding Proteins ,enzymes and coenzymes (carbohydrates) ,DNA Repair Enzymes ,KU-59436 ,030220 oncology & carcinogenesis ,Astrocytes ,embryonic structures ,KU-55933 ,biological phenomena, cell phenomena, and immunity ,Poly(ADP-ribose) Polymerases ,Homologous recombination ,Research Paper - Abstract
We recently demonstrated that human embryonic stem cells (hESCs) utilize homologous recombination repair (HRR) as primary means of double-strand break (DSB) repair. We now show that hESCs also use nonhomologous end joining (NHEJ). NHEJ kinetics were several-fold slower in hESCs and neural progenitors (NPs) than in astrocytes derived from hESCs. ATM and DNA-PKcs inhibitors were ineffective or partially effective, respectively, at inhibiting NHEJ in hESCs, whereas progressively more inhibition was seen in NPs and astrocytes. The lack of any major involvement of DNA-PKcs in NHEJ in hESCs was supported by siRNA-mediated DNA-PKcs knockdown. Expression of a truncated XRCC4 decoy or XRCC4 knock-down reduced NHEJ by more than half suggesting that repair is primarily canonical NHEJ. Poly(ADP-ribose) polymerase (PARP) was dispensable for NHEJ suggesting that repair is largely independent of backup NHEJ. Furthermore, as hESCs differentiated a progressive decrease in the accuracy of NHEJ was observed. Altogether, we conclude that NHEJ in hESCs is largely independent of ATM, DNA-PKcs, and PARP but dependent on XRCC4 with repair fidelity several-fold greater than in astrocytes.
- Published
- 2010
24. Dynamic dependence on ATR and ATM for double-strand break repair in human embryonic stem cells and neural descendants
- Author
-
Kristoffer Valerie, Bret R. Adams, Raj R. Rao, and Sarah E. Golding
- Subjects
DNA Repair ,DNA repair ,DNA damage ,Cellular differentiation ,RAD51 ,lcsh:Medicine ,Cell Cycle Proteins ,Ataxia Telangiectasia Mutated Proteins ,Biology ,Protein Serine-Threonine Kinases ,Cell Biology/Cell Signaling ,03 medical and health sciences ,0302 clinical medicine ,Radiation, Ionizing ,Humans ,Cell Lineage ,DNA Breaks, Double-Stranded ,lcsh:Science ,Cells, Cultured ,Embryonic Stem Cells ,030304 developmental biology ,Neurons ,0303 health sciences ,Multidisciplinary ,Molecular Biology/DNA Repair ,Tumor Suppressor Proteins ,lcsh:R ,Embryonic stem cell ,Molecular biology ,Double Strand Break Repair ,Cell biology ,Developmental Biology/Stem Cells ,Non-homologous end joining ,DNA-Binding Proteins ,enzymes and coenzymes (carbohydrates) ,030220 oncology & carcinogenesis ,Astrocytes ,embryonic structures ,lcsh:Q ,Rad51 Recombinase ,biological phenomena, cell phenomena, and immunity ,Homologous recombination ,Research Article - Abstract
The DNA double-strand break (DSB) is the most toxic form of DNA damage. Studies aimed at characterizing DNA repair during development suggest that homologous recombination repair (HRR) is more critical in pluripotent cells compared to differentiated somatic cells in which nonhomologous end joining (NHEJ) is dominant. We have characterized the DNA damage response (DDR) and quality of DNA double-strand break (DSB) repair in human embryonic stem cells (hESCs), and in vitro-derived neural cells. Resolution of ionizing radiation-induced foci (IRIF) was used as a surrogate for DSB repair. The resolution of gamma-H2AX foci occurred at a slower rate in hESCs compared to neural progenitors (NPs) and astrocytes perhaps reflective of more complex DSB repair in hESCs. In addition, the resolution of RAD51 foci, indicative of active homologous recombination repair (HRR), showed that hESCs as well as NPs have high capacity for HRR, whereas astrocytes do not. Importantly, the ATM kinase was shown to be critical for foci formation in astrocytes, but not in hESCs, suggesting that the DDR is different in these cells. Blocking the ATM kinase in astrocytes not only prevented the formation but also completely disassembled preformed repair foci. The ability of hESCs to form IRIF was abrogated with caffeine and siRNAs targeted against ATR, implicating that hESCs rely on ATR, rather than ATM for regulating DSB repair. This relationship dynamically changed as cells differentiated. Interestingly, while the inhibition of the DNA-PKcs kinase (and presumably non-homologous endjoining [NHEJ]) in astrocytes slowed IRIF resolution it did not in hESCs, suggesting that repair in hESCs does not utilize DNA-PKcs. Altogether, our results show that hESCs have efficient DSB repair that is largely ATR-dependent HRR, whereas astrocytes critically depend on ATM for NHEJ, which, in part, is DNA-PKcs-independent.
- Published
- 2010
25. Nuclear factor I isoforms regulate gene expression during the differentiation of human neural progenitors to astrocytes
- Author
-
Katarzyna M. Wilczynska, Lauren Bryan, Sandeep Singh, Irene Griswold-Prenner, Sarah Wright, Bret R. Adams, Tomasz Kordula, Kristoffer Valerie, and Raj R. Rao
- Subjects
Cellular differentiation ,Biology ,Models, Biological ,Article ,Cell Line ,Astrocyte differentiation ,Mice ,Gene expression ,Glial Fibrillary Acidic Protein ,Animals ,Humans ,Protein Isoforms ,Neuroinflammation ,Gliogenesis ,Regulation of gene expression ,Neurons ,Extracellular Matrix Proteins ,Glial fibrillary acidic protein ,Stem Cells ,Calcium-Binding Proteins ,Cell Differentiation ,Cell Biology ,Cell biology ,NFI Transcription Factors ,Gene Expression Regulation ,Astrocytes ,biology.protein ,Molecular Medicine ,Stem cell ,Developmental Biology - Abstract
Even though astrocytes are critical for both normal brain functions and the development and progression of neuropathological states, including neuroinflammation associated with neurodegenerative diseases, the mechanisms controlling gene expression during astrocyte differentiation are poorly understood. Thus far, several signaling pathways were shown to regulate astrocyte differentiation, including JAK-STAT, bone morphogenic protein-2/Smads, and Notch. More recently, a family of nuclear factor-1 (NFI-A, -B, -C, and -X) was implicated in the regulation of vertebral neocortex development, with NFI-A and -B controlling the onset of gliogenesis. Here, we developed an in vitro model of differentiation of stem cells towards neural progenitors (NP) and subsequently astrocytes. The transition from stem cells to progenitors was accompanied by an expected change in the expression profile of markers, including Sox-2, Musashi-1, and Oct4. Subsequently, generated astrocytes were characterized by proper morphology, increased glutamate uptake, and marker gene expression. We used this in vitro differentiation model to study the expression and functions of NFIs. Interestingly, stem cells expressed only background levels of NFIs, while differentiation to NP activated the expression of NFI-A. More importantly, NFI-X expression was induced during the later stages of differentiation towards astrocytes. In addition, NFI-X and -C were required for the expression of glial fibrillary acidic protein and secreted protein acidic and rich in cystein-like protein 1, which are the markers of astrocytes at the later stages of differentiation. We conclude that an expression program of NFIs is executed during the differentiation of astrocytes, with NFI-X and -C controlling the expression of astrocytic markers at late stages of differentiation. Disclosure of potential conflicts of interest is found at the end of this article.
- Published
- 2009
26. In Vivo and In Vitro Human Brain Tumor Models for Improving the Therapeutic Ratio of Ionizing Radiation and DNA Repair Inhibitors
- Author
-
G. Enikopolov, H. Saleh, Sarah E. Golding, Jason M. Beckta, Bret R. Adams, Laura Biddlestone-Thorpe, and Kristoffer Valerie
- Subjects
Cancer Research ,Pathology ,medicine.medical_specialty ,Radiation ,DNA repair ,business.industry ,Human brain tumor ,Cancer ,medicine.disease ,In vitro ,Ionizing radiation ,Therapeutic index ,Oncology ,In vivo ,Cancer research ,medicine ,Radiology, Nuclear Medicine and imaging ,business - Published
- 2011
27. Abstract 1450: Targeting the ATM kinase as a novel strategy for radiosensitizing glioblastoma multiforme in mice
- Author
-
Laura Biddlestone-Thorpe, Kristoffer Valerie, Elizabeth Rosenberg, Bret R. Adams, Mark J. O'Connor, Mary E. Tokarz, Sarah E. Golding, Ashraf A. Khalil, Sajjad Muhammad, and Donna Gilfor
- Subjects
Cancer Research ,Oncology ,Chemistry ,medicine ,Cancer research ,medicine.disease ,Atm kinase ,Glioblastoma - Abstract
Glioblastoma multiforme (GBM) is the most lethal type of brain cancer. At best, mean survival is only 12-15 months so an improvement of current therapy is long overdue. Current treatment includes surgery and chemoradiation. The short survival of GBM patients is due, in part, to the innate radioresistance and vicious invasiveness of GBM. ATM, ataxia telangiectasia (A-T) mutated, would be an excellent target for radiosensitizing GBM because of its critical role in regulating the DNA damage response (DDR) and other cellular processes. As a first step towards this goal, we tested the ability of the novel ATM kinase inhibitor KU-60019 to radiosensitize GBM in mice. Using an orthotopic xenograft model of GBM, nude mice were implanted with human glioma cells expressing reporter genes for monitoring tumor growth and spread. KU-60019 was administered intra-cranially by convection-enhanced delivery or by osmotic pump. Imaging, survival, and signs of inhibiting the DDR using immunohistochemistry were used to characterize the effects of KU-60019 on tumor and normal brain. Our results show that compared with untreated, KU-60019 alone, or radiation alone treated mice, the combined effect of KU-60019 and radiation significantly increased survival at least 2-fold and sometimes even cured the animals. Multiple glioma cell lines with varied genetic backgrounds are currently being tested. Altogether, our results show that KU-60019 is able to overcome GBM radioresistance, a major obstacle in the treatment of GBM, and significantly prolong the survival of animals. Thus, an ATM kinase inhibitor may have great potential as adjuvant therapy in the clinic. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1450. doi:1538-7445.AM2012-1450
- Published
- 2012
28. Mutations in the BRCT binding site of BRCA1 result in hyper-recombination
- Author
-
John M. Quillin, Elizabeth Rosenberg, Sarah E. Golding, Nicholas C.K. Valerie, Michael O. Idowu, Lawrence F. Povirk, Bo Xu, Kristoffer Valerie, Seth M. Dever, and Bret R. Adams
- Subjects
0303 health sciences ,Aging ,Mutation ,biology ,DNA repair ,DNA damage ,RAD51 ,Cell Biology ,medicine.disease_cause ,Molecular biology ,3. Good health ,enzymes and coenzymes (carbohydrates) ,03 medical and health sciences ,Promyelocytic leukemia protein ,0302 clinical medicine ,BRCT domain ,030220 oncology & carcinogenesis ,medicine ,biology.protein ,Nuclear protein ,Homologous recombination ,030304 developmental biology - Abstract
We introduced a K1702M mutation in the BRCA1 BRCT domain known to prevent the binding of proteins harboring pS-X-X-F motifs such as Abraxas-RAP80, BRIP1, and CtIP. Surprisingly, rather than impairing homologous recombination repair (HRR), expression of K1702M resulted in hyper-recombination coinciding with an accumulation of cells in S-G2 and no effect on nonhomologous end-joining. These cells also showed increased RAD51 and RPA nuclear staining. More pronounced effects were seen with a naturally occurring BRCT mutant (M1775R) that also produced elevated levels of ssDNA, in part co-localizing with RPA, in line with excessive DNA resection. M1775R induced unusual, thread-like promyelocytic leukemia (PML) nuclear bodies and clustered RPA foci rather than the typical juxtaposed RPA-PML foci seen with wild-type BRCA1. Interestingly, K1702M hyper-recombination diminished with a second mutation in the BRCA1 RING domain (I26A) known to reduce BRCA1 ubiquitin-ligase activity. Thesein vitro findings correlated with elevated nuclear RAD51 and RPA staining of breast cancer tissue from a patient with the M1775R mutation. Altogether, the disruption of BRCA1 (BRCT)-pS-X-X-F protein binding results in ubiquitination-dependent hyper-recombination via excessive DNA resection and the appearance of atypical PML-NBs. Thus, certain BRCA1 mutations that cause hyper-recombination instead of reduced DSB repair might lead to breast cancer.
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.