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Chen M, Marrs B, Qi L, Knifley T, Weiss HL, D’Orazio JA, O’Connor KL. Integrin α6β4 signals through DNA damage response pathway to sensitize breast cancer cells to cisplatin. Front Oncol 2022; 12:1043538. [PMID: 36439467 PMCID: PMC9686853 DOI: 10.3389/fonc.2022.1043538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/25/2022] [Indexed: 11/11/2022] Open
Abstract
Integrin α6β4 is highly expressed in triple negative breast cancer (TNBC) and drives its most aggressive traits; however, its impact on chemotherapeutic efficacy remains untested. We found that integrin α6β4 signaling promoted sensitivity to cisplatin and carboplatin but not to other chemotherapies tested. Mechanistic investigations revealed that integrin α6β4 stimulated the activation of ATM, p53, and 53BP1, which required the integrin β4 signaling domain. Genetic manipulation of gene expression demonstrated that mutant p53 cooperated with integrin α6β4 for cisplatin sensitivity and was necessary for downstream phosphorylation of 53BP1 and enhanced ATM activation. Additionally, we found that in response to cisplatin-induced DNA double strand break (DSB), integrin α6β4 suppressed the homologous recombination (HR) activity and enhanced non-homologous end joining (NHEJ) repair activity. Finally, we discovered that integrin α6β4 preferentially activated DNA-PK, facilitated DNA-PK-p53 and p53-53BP1 complex formation in response to cisplatin and required DNA-PK to enhance ATM, 53BP1 and p53 activation as well as cisplatin sensitivity. In summary, we discovered a novel function of integrin α6β4 in promoting cisplatin sensitivity in TNBC through DNA damage response pathway.
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Affiliation(s)
- Min Chen
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, United States
| | - Brock Marrs
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
| | - Lei Qi
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
| | - Teresa Knifley
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
| | - Heidi L. Weiss
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
- Department of Biostatistics, University of Kentucky, Lexington, KY, United States
| | - John A. D’Orazio
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
- Department of Pediatrics, University of Kentucky, Lexington, KY, United States
| | - Kathleen L. O’Connor
- Markey Cancer Center, University of Kentucky, Lexington, KY, United States
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, United States
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Alghfeli L, Parambath D, Manzoor S, Roach HI, Oreffo RO, El-Serafi AT. Synthesis of scaffold-free, three dimensional, osteogenic constructs following culture of skeletal osteoprogenitor cells on glass surfaces. Bone Rep 2021; 15:101143. [PMID: 34746337 PMCID: PMC8554168 DOI: 10.1016/j.bonr.2021.101143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Efficient differentiation of stem cells into three-dimensional (3D) osteogenic construct is still an unmet challenge. These constructs can be crucial for patients with bone defects due to congenital or traumatic reasons. The modulation of cell fate and function as a consequence of interaction with the physical and chemical properties of materials is well known. METHODS The current study has examined the osteogenic differentiation potential of human skeletal populations following culture on glass surfaces, as a monolayer, or in glass tubes as a pellet culture. The 3D prosperities were assessed morphometrically and the differentiation was evaluated through molecular characterization as well as matrix formation. RESULTS Early temporal expression of alkaline phosphatase expression of skeletal populations was observed following culture on glass surfaces. Skeletal populations seeded on glass tubes, adhered as a monolayer to the tube base and subsequently formed 3D pellets at the air -media interface. The pellets cultured on glass displayed 4.9 ± 1.3 times the weight and 2.9 ± 0.1 the diameter of their counterpart cultured in plastic tubes and displayed enhanced production of osteogenic matrix proteins, such a collagen I and osteonectin. The size and weight of the pellets correlated with surface area in contrast to cell numbers seeded. Global DNA methylation level was decreased in pellets cultured on glass. In contrast, gene expression analysis confirmed upregulation extracellular matrix proteins and osteogenesis-related growth factors. CONCLUSION This simple approach to the culture of skeletal cells on glass tubes provides a scaffold-free, 3D construct platform for generating pellets enabling analysis and evaluation of tissue development and integration of multiple constructs with implications for tissue repair and regenerative application on scale-up.
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Key Words
- 3D culture
- 3D, three-dimensional
- A/S, Alcian blue/Sirius red/Weigert's haematoxylin
- ALP, Alkaline Phosphatase
- BMP, bone morphogenic protein
- BMSC, human bone marrow stromal
- CSF, colony stimulating factor
- Ct, Cycle threshold
- Differentiation
- EGF, epidermal growth factor
- FC, Fetal bone cells
- FCS, Fetal Calf Serum
- FGF, fibroblast growth factor
- FN1, fibronectin
- GLI, GLI family zinc finger 1
- HIPPIE, Human Integrated Protein Interaction Reference
- ITGA3, integrin A3
- MMP, matrix metalloprotease
- Osteogenesis
- Osteoprogenitor cells
- P/S, penicillin and streptomycin
- Pellets
- R, receptor
- TGF, β transforming growth factor beta
- TGFBR2 transforming growth factor beta receptor 2 VDR, vitamin D receptor
- gDNA, genomic DNA
- iMSC, immortalized human bone marrow derived, mesenchymal stem cells
- vWF, von Willebrand factor
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Affiliation(s)
- Latifa Alghfeli
- Research Institute for Medical and Health Sciences, University of Sharjah, United Arab Emirates
| | - Divyasree Parambath
- Research Institute for Medical and Health Sciences, University of Sharjah, United Arab Emirates
| | - Shaista Manzoor
- Research Institute for Medical and Health Sciences, University of Sharjah, United Arab Emirates
| | - Helmtrud I. Roach
- Bone and Joint Research Group, Institute of Developmental Sciences, University of Southampton, School of Medicine, UK
| | - Richard O.C. Oreffo
- Bone and Joint Research Group, Institute of Developmental Sciences, University of Southampton, School of Medicine, UK
| | - Ahmed T. El-Serafi
- Research Institute for Medical and Health Sciences, University of Sharjah, United Arab Emirates
- Medical Biochemistry Department, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
- Department of Biomedical and Clinical Sciences (BKV), Linköping University, Sweden
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Bakalkin G, Kahle A, Sarkisyan D, Watanabe H, Lukoyanov N, Carvalho LS, Galatenko V, Hallberg M, Nosova O. Coordinated expression of the renin-angiotensin genes in the lumbar spinal cord: Lateralization and effects of unilateral brain injury. Eur J Neurosci 2021; 54:5560-5573. [PMID: 34145943 DOI: 10.1111/ejn.15360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/29/2021] [Accepted: 06/17/2021] [Indexed: 12/19/2022]
Abstract
In spite of its apparent symmetry, the spinal cord is asymmetric in its reflexes and gene expression patterns including leftward expression bias of the opioid and glutamate genes. To examine whether this is a general phenomenon for neurotransmitter and neurohormonal genes, we here characterized expression and co-expression (transcriptionally coordinated) patterns of genes of the renin-angiotensin system (RAS) that is involved in neuroprotection and pathological neuroplasticity in the left and right lumbar spinal cord. We also tested whether the RAS expression patterns were affected by unilateral brain injury (UBI) that rewired lumbar spinal neurocircuits. The left and right halves of the lumbar spinal cord were analysed in intact rats, and rats with left- or right-sided unilateral cortical injury, and left- or right-sided sham surgery. The findings were (i) lateralized expression of the RAS genes Ace, Agtr2 and Ren with higher levels on the left side; (ii) the asymmetry in coordination of the RAS gene expression that was stronger on the right side; (iii) the decay in coordination of co-expression of the RAS and neuroplasticity-related genes induced by the right-side but not left-side sham surgery and UBI; and (iv) the UBI-induced shift to negative regulatory interactions between RAS and neuroplasticity-related genes on the contralesional spinal side. Thus, the RAS genes may be a part of lateralized gene co-expression networks and have a role in a side-specific regulation of spinal neurocircuits.
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Affiliation(s)
- Georgy Bakalkin
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Anika Kahle
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Daniil Sarkisyan
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Hiroyuki Watanabe
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Nikolay Lukoyanov
- Departamento de Biomedicina, Faculdade de Medicina; Instituto de Investigação e Inovação em Saúde; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Liliana S Carvalho
- Departamento de Biomedicina, Faculdade de Medicina; Instituto de Investigação e Inovação em Saúde; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Vladimir Galatenko
- Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow, Russia.,Evotec International GmbH, Göttingen, Germany
| | - Mathias Hallberg
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Olga Nosova
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Unilateral traumatic brain injury of the left and right hemisphere produces the left hindlimb response in rats. Exp Brain Res 2021; 239:2221-2232. [PMID: 34021800 PMCID: PMC8282563 DOI: 10.1007/s00221-021-06118-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/20/2021] [Indexed: 12/28/2022]
Abstract
Traumatic brain injury and stroke result in hemiplegia, hemiparesis, and asymmetry in posture. The effects are mostly contralateral; however, ipsilesional deficits may also develop. We here examined whether ablation brain injury and controlled cortical impact (CCI), a rat model of clinical focal traumatic brain injury, both centered over the left or right sensorimotor cortex, induced hindlimb postural asymmetry (HL-PA) with contralesional or ipsilesional limb flexion. The contralesional hindlimb was flexed after left or right side ablation injury. In contrast, both the left and right CCI unexpectedly produced HL-PA with flexion on left side. The flexion persisted after complete spinal cord transection suggesting that CCI triggered neuroplastic processes in lumbar neural circuits enabling asymmetric muscle contraction. Left limb flexion was exhibited under pentobarbital anesthesia. However, under ketamine anesthesia, the body of the left and right CCI rats bent laterally in the coronal plane to the ipsilesional side suggesting that the left and right injury engaged mirror-symmetrical motor pathways. Thus, the effects of the left and right CCI on HL-PA were not mirror-symmetrical in contrast to those of the ablation brain injury, and to the left and right CCI produced body bending. Ipsilateral effects of the left CCI on HL-PA may be mediated by a lateralized motor pathway that is not affected by the left ablation injury. Alternatively, the left-side-specific neurohormonal mechanism that signals from injured brain to spinal cord may be activated by both the left and right CCI but not by ablation injury.
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Carvalho LS, Brito HM, Lukoyanova EA, Maia GH, Sarkisyan D, Nosova O, Zhang M, Lukoyanov N, Bakalkin G. Unilateral brain injury to pregnant rats induces asymmetric neurological deficits in the offspring. Eur J Neurosci 2021; 53:3621-3633. [PMID: 33884684 DOI: 10.1111/ejn.15243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/30/2021] [Accepted: 04/15/2021] [Indexed: 12/27/2022]
Abstract
Effects of environmental factors may be transmitted to the following generation, and cause neuropsychiatric disorders including depression, anxiety, and posttraumatic stress disorder in the offspring. Enhanced synaptic plasticity induced by environmental enrichment may be also transmitted. We here test the hypothesis that the effects of brain injury in pregnant animals may produce neurological deficits in the offspring. Unilateral brain injury (UBI) by ablation of the hindlimb sensorimotor cortex in pregnant rats resulted in the development of hindlimb postural asymmetry (HL-PA), and impairment of balance and coordination in beam walking test in the offspring. The offspring of rats with the left UBI exhibited HL-PA before and after spinal cord transection with the contralesional (i.e., right) hindlimb flexion. The right UBI caused the offspring to develop HL-PA that however was cryptic and not-lateralized; it was evident only after spinalization, and was characterized by similar occurrence of the ipsi- and contralesional hindlimb flexion. The HL-PA persisted after spinalization suggesting that the asymmetry was encoded in lumbar spinal neurocircuits that control hindlimb muscles. Balance and coordination were affected by the right UBI but not the left UBI. Thus, the effects of a unilateral brain lesion in pregnant animals may be intergenerationally transmitted, and this process may depend on the side of brain injury. The results suggest the existence of left-right side-specific mechanisms that mediate transmission of the lateralized effects of brain trauma from mother to fetus.
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Affiliation(s)
- Liliana S Carvalho
- Departamento de Biomedicina da Faculdade de Medicina da Universidade do Porto, Instituto de Investigação e Inovação em Saúde, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Helena M Brito
- Departamento de Biomedicina da Faculdade de Medicina da Universidade do Porto, Instituto de Investigação e Inovação em Saúde, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Elena A Lukoyanova
- Departamento de Biomedicina da Faculdade de Medicina da Universidade do Porto, Instituto de Investigação e Inovação em Saúde, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Gisela H Maia
- Departamento de Biomedicina da Faculdade de Medicina da Universidade do Porto, Instituto de Investigação e Inovação em Saúde, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Daniil Sarkisyan
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Olga Nosova
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Mengliang Zhang
- Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Nikolay Lukoyanov
- Departamento de Biomedicina da Faculdade de Medicina da Universidade do Porto, Instituto de Investigação e Inovação em Saúde, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Georgy Bakalkin
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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Signatures of Dermal Fibroblasts from RDEB Pediatric Patients. Int J Mol Sci 2021; 22:ijms22041792. [PMID: 33670258 PMCID: PMC7918539 DOI: 10.3390/ijms22041792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 12/13/2022] Open
Abstract
The recessive form of dystrophic epidermolysis bullosa (RDEB) is a debilitating disease caused by impairments in the junctions of the dermis and the basement membrane of the epidermis. Mutations in the COL7A1 gene induce multiple abnormalities, including chronic inflammation and profibrotic changes in the skin. However, the correlations between the specific mutations in COL7A1 and their phenotypic output remain largely unexplored. The mutations in the COL7A1 gene, described here, were found in the DEB register. Among them, two homozygous mutations and two cases of compound heterozygous mutations were identified. We created the panel of primary patient-specific RDEB fibroblast lines (FEB) and compared it with control fibroblasts from healthy donors (FHC). The set of morphological features and the contraction capacity of the cells distinguished FEB from FHC. We also report the relationships between the mutations and several phenotypic traits of the FEB. Based on the analysis of the available RNA-seq data of RDEB fibroblasts, we performed an RT-qPCR gene expression analysis of our cell lines, confirming the differential status of multiple genes while uncovering the new ones. We anticipate that our panels of cell lines will be useful not only for studying RDEB signatures but also for investigating the overall mechanisms involved in disease progression.
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Stahler A, Stintzing S, Modest DP, Ricard I, Giessen-Jung C, Kapaun C, Ivanova B, Kaiser F, Fischer von Weikersthal L, Moosmann N, Schalhorn A, Stauch M, Kiani A, Held S, Decker T, Moehler M, Neumann J, Kirchner T, Jung A, Heinemann V. Amphiregulin Expression Is a Predictive Biomarker for EGFR Inhibition in Metastatic Colorectal Cancer: Combined Analysis of Three Randomized Trials. Clin Cancer Res 2020; 26:6559-6567. [PMID: 32943459 DOI: 10.1158/1078-0432.ccr-20-2748] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/18/2020] [Accepted: 09/10/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE Amphiregulin (AREG) and epiregulin (EREG) are ligands of EGFR. Predictive information for anti-EGFR treatment in metastatic colorectal cancer (mCRC) was observed, but data for other agents is limited. EXPERIMENTAL DESIGN Ligand mRNA expression; RAS, BRAF, PIK3CA mutations; and EGFR expression were assessed by qRT-PCR, pyrosequencing, and IHC, respectively, in mCRC tumor tissue of patients participating in the randomized controlled trials FIRE-1, CIOX, and FIRE-3. Normalized mRNA expression was dichotomized using median and third quartile. Overall (OS) and progression-free survival (PFS) were estimated by Kaplan-Meier method including univariate and multivariate Cox regression analyses. Penalized spline regression analysis tested interaction of mRNA expression and outcome. RESULTS Of 688 patients with available material, high AREG expression was detected in 343 (>median) and 172 (>3rd quartile) patients. High AREG expression was associated with significantly higher OS [26.2 vs. 21.5 months, HR = 0.80; 95% confidence interval (CI), 0.68-0.94; P = 0.007], PFS (10.0 vs. 8.1 months, HR = 0.74; 95% CI, 0.63-0.86; P = 0.001), and objective response rate (63.1% vs. 51.6%, P = 0.004) compared to low expression at both threshold values. This effect remained significant in multivariate Cox regression analysis (OS: P = 0.01, PFS: P = 0.002). High AREG mRNA expression interacted significantly with the efficacy of cetuximab compared with bevacizumab (OS: P = 0.02, PFS: P = 0.04) in RAS WT mCRC. CONCLUSIONS High AREG mRNA expression is a favorable prognostic biomarker for mCRC which interacted significantly with efficacy of anti-EGFR treatment.
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Affiliation(s)
- Arndt Stahler
- Department of Internal Medicine III and Comprehensive Cancer Centre Munich, University Hospital Grosshadern, Ludwig-Maximilian-Universitaet Muenchen, Munich, Germany.
| | - Sebastian Stintzing
- Medical Department, Division of Hematology, Oncology and Tumor Immunology (CCM), Charité Universitaetsmedizin Berlin, Berlin, Germany.,DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany
| | - Dominik P Modest
- DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany.,Medical Department, Division of Hematology, Oncology and Tumor Immunology (CVK), Charité Universitaetsmedizin Berlin, Berlin, Germany
| | - Ingrid Ricard
- Department of Internal Medicine III and Comprehensive Cancer Centre Munich, University Hospital Grosshadern, Ludwig-Maximilian-Universitaet Muenchen, Munich, Germany
| | - Clemens Giessen-Jung
- Department of Internal Medicine III and Comprehensive Cancer Centre Munich, University Hospital Grosshadern, Ludwig-Maximilian-Universitaet Muenchen, Munich, Germany
| | - Christine Kapaun
- Institute of Pathology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Boryana Ivanova
- Institute of Pathology, Faculty of Medicine, LMU Munich, Munich, Germany
| | | | | | - Nicolas Moosmann
- Department for Hematology and Oncology, Klinikum Barmherzige Brüder, Regensburg, Germany
| | - Andreas Schalhorn
- Department of Internal Medicine III and Comprehensive Cancer Centre Munich, University Hospital Grosshadern, Ludwig-Maximilian-Universitaet Muenchen, Munich, Germany
| | | | - Alexander Kiani
- Department of Medicine IV, Klinikum Bayreuth GmbH, Bayreuth, Germany
| | | | | | - Markus Moehler
- I. Department of Internal Medicine, University Medical Center Mainz, Mainz, Germany
| | - Jens Neumann
- DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany.,Institute of Pathology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Thomas Kirchner
- DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany.,Institute of Pathology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Andreas Jung
- DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany.,Institute of Pathology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Volker Heinemann
- Department of Internal Medicine III and Comprehensive Cancer Centre Munich, University Hospital Grosshadern, Ludwig-Maximilian-Universitaet Muenchen, Munich, Germany.,DKTK, German Cancer Consortium, German Cancer Research Centre (DKFZ), Heidelberg, Germany
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Revealing the epigenetic effect of temozolomide on glioblastoma cell lines in therapeutic conditions. PLoS One 2020; 15:e0229534. [PMID: 32101575 PMCID: PMC7043761 DOI: 10.1371/journal.pone.0229534] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 02/07/2020] [Indexed: 12/19/2022] Open
Abstract
Temozolomide (TMZ) is a drug of choice in glioblastoma treatment. Its therapeutic applications expand also beyond high grade gliomas. However, a significant number of recurrences and resistance to the drug is observed. The key factor in each chemotherapy is to achieve the therapeutic doses of a drug at the pathologic site. Nonetheless, the rate of temozolomide penetration from blood to cerebrospinal fluid is only 20–30%, and even smaller into brain intestinum. That makes a challenge for the therapeutic regimens to obtain effective drug concentrations with minimal toxicity and minor side effects. The aim of our research was to explore a novel epigenetic mechanism of temozolomide action in therapeutic conditions. We analyzed the epigenetic effects of TMZ influence on different glioblastoma cell lines in therapeutically achieved TMZ concentrations through total changes of the level of 5-methylcytosine in DNA, the main epigenetic marker. That was done with classical approach of radioactive nucleotide post-labelling and separation on thin-layer chromatography. In the range of therapeutically achieved temozolomide concentrations we observed total DNA hypomethylation. The significant hypermethylating effect was visible after reaching TMZ concentrations of 10–50 μM (depending on the cell line). Longer exposure time promoted DNA hypomethylation. The demethylated state of the glioblastoma cell lines was overcome by repeated TMZ applications, where dose-dependent increase in DNA 5-methylcytosine contents was observed. Those effects were not seen in non-cancerous cell line. The increase of DNA methylation resulting in global gene silencing and consecutive down regulation of gene expression after TMZ treatment may explain better glioblastoma patients’ survival.
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