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Not Only Mutations Matter: Molecular Picture of Acute Myeloid Leukemia Emerging from Transcriptome Studies. JOURNAL OF ONCOLOGY 2019; 2019:7239206. [PMID: 31467542 PMCID: PMC6699387 DOI: 10.1155/2019/7239206] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/12/2019] [Indexed: 01/08/2023]
Abstract
The last two decades of genome-scale research revealed a complex molecular picture of acute myeloid leukemia (AML). On the one hand, a number of mutations were discovered and associated with AML diagnosis and prognosis; some of them were introduced into diagnostic tests. On the other hand, transcriptome studies, which preceded AML exome and genome sequencing, remained poorly translated into clinics. Nevertheless, gene expression studies significantly contributed to the elucidation of AML pathogenesis and indicated potential therapeutic directions. The power of transcriptomic approach lies in its comprehensiveness; we can observe how genome manifests its function in a particular type of cells and follow many genes in one test. Moreover, gene expression measurement can be combined with mutation detection, as high-impact mutations are often present in transcripts. This review sums up 20 years of transcriptome research devoted to AML. Gene expression profiling (GEP) revealed signatures distinctive for selected AML subtypes and uncovered the additional within-subtype heterogeneity. The results were particularly valuable in the case of AML with normal karyotype which concerns up to 50% of AML cases. With the use of GEP, new classes of the disease were identified and prognostic predictors were proposed. A plenty of genes were detected as overexpressed in AML when compared to healthy control, including KIT, BAALC, ERG, MN1, CDX2, WT1, PRAME, and HOX genes. High expression of these genes constitutes usually an unfavorable prognostic factor. Upregulation of FLT3 and NPM1 genes, independent on their mutation status, was also reported in AML and correlated with poor outcome. However, transcriptome is not limited to the protein-coding genes; other types of RNA molecules exist in a cell and regulate genome function. It was shown that microRNA (miRNA) profiles differentiated AML groups and predicted outcome not worse than protein-coding gene profiles. For example, upregulation of miR-10a, miR-10b, and miR-196b and downregulation of miR-192 were found as typical of AML with NPM1 mutation whereas overexpression of miR-155 was associated with FLT3-internal tandem duplication (FLT3-ITD). Development of high-throughput technologies and microarray replacement by next generation sequencing (RNA-seq) enabled uncovering a real variety of leukemic cell transcriptomes, reflected by gene fusions, chimeric RNAs, alternatively spliced transcripts, miRNAs, piRNAs, long noncoding RNAs (lncRNAs), and their special type, circular RNAs. Many of them can be considered as AML biomarkers and potential therapeutic targets. The relations between particular RNA puzzles and other components of leukemic cells and their microenvironment, such as exosomes, are now under investigation. Hopefully, the results of this research will shed the light on these aspects of AML pathogenesis which are still not completely understood.
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Wang R, Xue X, Wang Y, Zhao H, Zhang Y, Wang H, Miao D. BMI1 Deficiency Results in Female Infertility by Activating p16/p19 Signaling and Increasing Oxidative Stress. Int J Biol Sci 2019; 15:870-881. [PMID: 30906217 PMCID: PMC6429020 DOI: 10.7150/ijbs.30488] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/12/2019] [Indexed: 01/20/2023] Open
Abstract
The polycomb repressor B lymphoma Mo-MLV insertion region 1 (BMI1) is a core composition of polycomb repressive complex 1 (PRC1) and contributes to diverse fundamental cellular processes including cell senescence, apoptosis and proliferation. To investigate the role and mechanism of BMI1 in maintaining normal female reproductive function, we compared the differences in reproductive phenotypes between Bmi1-deficient and wild-type female mice. The Bmi1-deficient female mice were then supplemented with N-acetylcysteine in their drinking water to explore whether antioxidant supplementation could improve reproductive dysfunction caused by BMI1 deficiency. The results revealed that Bmi1 deletion resulted in complete infertility in female mice, estrous cycle disorder, and follicular developmental disorders. The reactive oxygen species levels in the ovarian tissue were increased; the ability of antioxidant enzymes was downregulated; the expression levels of p19 and p53 proteins were significantly upregulated. We also found that oocytes derived from Bmi1-deficient mice could not develop into embryos by in vitro fertilization and in vitro culture of embryos. Furthermore, supplementation with the antioxidant NAC not only improved the reproductive defects caused by Bmi1 deletion, but also largely rescued the ability of Bmi1-deficient oocytes to develop into embryos in vitro. These results indicated that cells lacking Bmi1 resulted in female infertility by activating the p16/p19 signaling pathway, increasing oxidative stress and DNA damage, inhibiting granulosa cell proliferation, and inducing granulosa cell apoptosis. Thus, BMI1 may be a novel potential target for the clinical treatment of female infertility.
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Affiliation(s)
- Rong Wang
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xian Xue
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yang Wang
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Haiyang Zhao
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yuling Zhang
- Department of Ultrasound, Taikang Xianlin Drum Tower Hospital, Nanjing, Jiangsu, China
| | - Hui Wang
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Dengshun Miao
- State Key Laboratory of Reproductive Medicine, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, Jiangsu, China
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, Jiangsu, China
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Xia MY, Zhao XY, Huang QL, Sun HY, Sun C, Yuan J, He C, Sun Y, Huang X, Kong W, Kong WJ. Activation of Wnt/β-catenin signaling by lithium chloride attenuates d-galactose-induced neurodegeneration in the auditory cortex of a rat model of aging. FEBS Open Bio 2017; 7:759-776. [PMID: 28593132 PMCID: PMC5458451 DOI: 10.1002/2211-5463.12220] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 02/27/2017] [Accepted: 03/06/2017] [Indexed: 01/09/2023] Open
Abstract
Degeneration of the central auditory system, which is characterized by reduced understanding of speech and source localization of sounds, is an important cause of age‐related hearing loss (presbycusis). Accumulating evidence has demonstrated that Wnt/β‐catenin signaling plays an essential role in the development of the auditory system but its potential role in presbycusis remains unclear. In this study, we used a rat model of aging, created by chronic systemic exposure to d‐galactose (d‐gal), and explored changes in Wnt/β‐catenin signaling in the auditory cortex. A decrease in Wnt/β‐catenin signaling in the auditory cortex was found in both naturally aging and d‐gal‐mimetic aging rats, as indicated by increased GSK3β activity and decreased β‐catenin activity. Moreover, lithium chloride (Licl), an activator of Wnt signaling pathway, was administered long term to 15‐month‐old d‐gal‐treated rats. Activation of Wnt/β‐catenin signaling by Licl attenuated d‐gal‐induced auditory cortex apoptosis and neurodegeneration. Bmi1, a transcription factor implicated in antiaging and resistance to apoptosis, can be modulated by β‐catenin activity. Here, we showed that the expression of Bmi1 was reduced and the expression of its downstream genes, p16INK4a, p19Arf, and p53 were increased in the auditory cortex both of naturally aging and d‐gal‐mimetic aging rats. In addition, Licl significantly increased Bmi1 expression and reduced p16INK4a, p19Arf, and p53 expression. Our results indicated that decreased Wnt/β‐catenin signaling might participate in the pathogenesis of central presbycusis through modulating the expression of Bmi1. Wnt/β‐catenin signaling might be used as a potential therapeutic target against presbycusis.
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Affiliation(s)
- Ming-Yu Xia
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xue-Yan Zhao
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qi-Lin Huang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hai-Ying Sun
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chen Sun
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Yuan
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chang He
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiang Huang
- Institute of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wen Kong
- Department of Endocrinology, Union Hospital Tongji, Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei-Jia Kong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Asati V, Mahapatra DK, Bharti SK. PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways inhibitors as anticancer agents: Structural and pharmacological perspectives. Eur J Med Chem 2016; 109:314-41. [PMID: 26807863 DOI: 10.1016/j.ejmech.2016.01.012] [Citation(s) in RCA: 383] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 12/17/2022]
Abstract
The protein kinases regulate cellular functions such as transcription, translation, proliferation, growth and survival by the process of phosphorylation. Over activation of signaling pathways play a major role in oncogenesis. The PI3K signaling pathway is dysregulated almost in all cancers due to the amplification, genetic mutation of PI3K gene and the components of the PI3K pathway themselves. Stimulation of the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK pathways enhances growth, survival, and metabolism of cancer cells. Recently, the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways have been identified as promising therapeutic targets for cancer therapy. The kinase inhibitors with enhanced specificity and improved pharmacokinetics have been considered for design and development of anticancer agents. This review focuses primarily on the Ras/Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways as therapeutic targets of anticancer drugs, their specific and dual inhibitors, structure activity relationships (SARs) and inhibitors under clinical trials.
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Affiliation(s)
- Vivek Asati
- Institute of Pharmaceutical Sciences, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur 495009, Chhattisgarh, India
| | - Debarshi Kar Mahapatra
- Institute of Pharmaceutical Sciences, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur 495009, Chhattisgarh, India
| | - Sanjay Kumar Bharti
- Institute of Pharmaceutical Sciences, Guru Ghasidas Vishwavidyalaya (A Central University), Bilaspur 495009, Chhattisgarh, India.
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Gasiewicz TA, Singh KP, Bennett JA. The Ah receptor in stem cell cycling, regulation, and quiescence. Ann N Y Acad Sci 2014; 1310:44-50. [PMID: 24495120 DOI: 10.1111/nyas.12361] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Processes that regulate quiescence, self-renewal, and differentiation of hematopoietic stem cells (HSCs) are not well understood. Owing, in part, to the ability of xenobiotic ligands to have persistent effects on the immune system in experimental animals, there has been much work to define a physiological role of the aryl hydrocarbon receptor (AhR) and its relationship to human disease. Persistent AhR activation by dioxin, a potent agonist, results in altered numbers and function of HSCs in mice. HSCs from AhR(-/-) knockout (KO) mice are hyperproliferative and have an altered cell cycle. Aging KO mice show characteristics consistent with premature bone marrow exhaustion. We propose that the increased proliferation of HSCs lacking AhR expression or activity is a result of loss of quiescence, and as such, AhR normally acts as a negative regulator to curb excessive or unnecessary proliferation. Similarly, prolonged and/or inappropriate stimulation of AhR activity may compromise the ability of HSCs to sense environmental signals that allow these cells to balance quiescence, proliferation, migration, and differentiation. These data and others support a hypothesis that deregulation of AhR function has an important role in HSC regulation and in the etiology and/or progression of certain hematopoietic diseases, many of which are associated with aging.
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Affiliation(s)
- Thomas A Gasiewicz
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
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Singh KP, Bennett JA, Casado FL, Walrath JL, Welle SL, Gasiewicz TA. Loss of aryl hydrocarbon receptor promotes gene changes associated with premature hematopoietic stem cell exhaustion and development of a myeloproliferative disorder in aging mice. Stem Cells Dev 2013; 23:95-106. [PMID: 24138668 DOI: 10.1089/scd.2013.0346] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Loss of immune function and increased hematopoietic disease are among the most clinically significant consequences of aging. Hematopoietic stem cells (HSCs) from mice lacking aryl hydrocarbon receptor (AhR) have high rates of cell division. Studies were designed to test the hypothesis that aging AhR-null allele (AhR-KO) mice develop premature HSC exhaustion, and changes leading to hematological disease. Compared to wild-type, aging AhR-KO mice showed a decreased survival rate, splenomegaly, increased circulating white blood cells, hematopoietic cell accumulation in tissues, and anemia. Analysis of bone marrow indicated increased numbers of stem/progenitor and lineage-committed cells, but decreased erythroid progenitors. There was also decreased self-renewal capacity of HSCs determined by competitive repopulation and serial transplantation. HSCs also showed increased levels of reactive oxygen species (ROS), Ki-67, and γ-H2A.X, but decreased p16(Ink4a). Splenic cells from aging KO mice had abnormal expression of genes, including Gata-1, Sh2d3c, Gfi-1, p21, and c-myc, involved in trafficking and associated with leukemia. HSCs from AhR-KO mice had gene changes related to HSC maintenance and consistent with phenotype observed. The most prominent gene changes (overexpression of Srpk2, Creb1, Hes1, mtor, pdp1) have been associated with HSC hyperproliferation, leukemia, and accelerated aging. Pathway analyses also indicated an enrichment of genes associated with oxidative stress, acute myelogenous leukemia, aging, and heat shock response, and the β-catenin/Wnt pathways. These data indicate that loss of AhR and associated changes in multiple signaling pathways promote premature HSC exhaustion and development of a myeloproliferative disorder. They also implicate a critical role of the AhR in the regulation of HSCs.
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Affiliation(s)
- Kameshwar P Singh
- 1 Department of Environmental Medicine, University of Rochester School of Medicine , Rochester, New York
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Egbuniwe O, Grant AD, Renton T, Di Silvio L. Phenotype-independent effects of retroviral transduction in human dental pulp stem cells. Macromol Biosci 2013; 13:851-9. [PMID: 23765615 DOI: 10.1002/mabi.201300020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 04/05/2013] [Indexed: 01/03/2023]
Abstract
An immortalized human dental pulp stem cell (DPSC) line of an odontoblastic phenotype is established to circumvent the normal programmed senescence and to maintain the cell line's usefulness as a tool for further study of cellular activity. DPSCs are isolated from human dental pulp tissues and transfected using hTERT. The influence of this process on the DPSC phenotype and the mRNA expression of oncogenes involved in cellular senescence is investigated. The results reveal an absence of altered DPSC morphology and phenotype following the exogenous introduction of the hTERT gene, which is coupled with a significant reduction in p16 mRNA expression. This provides insight into how to circumvent in vitro dental pulp stem cell death following the exogenous introduction of hTERT.
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Affiliation(s)
- Obi Egbuniwe
- Biomaterials, Tissue Engineering and Imaging, King's College London, Guy's Hospital, London, England.
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Protection of acute myeloid leukaemia cells from apoptosis induced by front-line chemotherapeutics is mediated by haem oxygenase-1. Oncotarget 2012; 2:658-68. [PMID: 21911919 PMCID: PMC3248221 DOI: 10.18632/oncotarget.321] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Haem oxygenase-1 (HO-1) is increasingly regarded as a pro-tumoral target in the treatment of human cancers. Currently, little is known about HO-1 and its role in human acute myeloid leukaemia (AML) to regulate apoptosis in response to chemotherapy. Recently, we showed that HO-1 protects AML samples from tumour necrosis factor-α (TNF)-induced apoptosis - it being regulated by transcription factors Nrf2, NF-ĸB and AP-1. This study aims to analyse the role of HO-1 in regulating apoptosis in AML cells in response to two front-line chemotherapeutic agents used for AML, cytarabine and daunorubicin. Here we show that HO-1 expression in AML samples was increased in response to both cytarabine and daunorubicin treatment, and micro RNA (miRNA) silenced HO-1 expression in combination with either daunorubicin or cytarabine induced a greater apoptotic responses in AML cells. Moreover, we showed that both daunorubicin and cytarabine induced reactive oxygen species (ROS) accumulation to induce apoptosis in AML. However, ROS-dependent induction of HO-1 was limiting the apoptotic response that is seen in AML towards cytarabine and daunorubicin treatment. These findings suggest concurrent inhibition of HO-1 expression in conjunction with chemotherapeutic treatment would improve the number of cases who reach complete remission.
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Blagosklonny MV. Molecular damage in cancer: an argument for mTOR-driven aging. Aging (Albany NY) 2011; 3:1130-41. [PMID: 22246147 PMCID: PMC3273893 DOI: 10.18632/aging.100422] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 12/31/2011] [Indexed: 12/12/2022]
Abstract
Despite common belief, accumulation of molecular damage does not play a key role in aging. Still, cancer (an age-related disease) is initiated by molecular damage. Cancer and aging share a lot in common including the activation of the TOR pathway. But the role of molecular damage distinguishes cancer and aging. Furthermore, an analysis of the role of both damage and aging in cancer argues against "a decline, caused by accumulation of molecular damage" as a cause of aging. I also discuss how random molecular damage, via rounds of multiplication and selection, brings about non-random hallmarks of cancer.
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Affiliation(s)
- Mikhail V Blagosklonny
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
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Egbuniwe O, Idowu BD, Funes JM, Grant AD, Renton T, Di Silvio L. P16/p53 expression and telomerase activity in immortalized human dental pulp cells. Cell Cycle 2011; 10:3912-9. [PMID: 22067611 PMCID: PMC3266118 DOI: 10.4161/cc.10.22.18093] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/13/2011] [Accepted: 09/14/2011] [Indexed: 01/09/2023] Open
Abstract
INTRODUCTION Residing within human dental pulp are cells of an ectomesenchymal origin which have the potential to differentiate into odontoblast-like cells. These cells have a limited growth potential owing to the effects of cell senescence. This study examines the effects of immortalizing odontoblast-like cells on cell proliferation and mineralization by comparing transformed dental pulp stem cells (tDPSCs) and non-transformed dental pulp stem cells (nDPSCs). RESULTS With the exogenous expression of hTERT, tDPSCs maintained a continued expression of odontogenic markers for cell proliferation and mineralization (ALP, COL-1, DMP-1, DSPP, OCN amd OPN)as did nDPScs. Oncoprotein expression was seen in both groups except for a noted absence of p16 in the tDPSCs. nDPSCs also showed lower levels of total ALP and DNA activity in comparison to tDPSCs when assayed as well as low telomerase activity readings. METHODS Using a retroviral vector, exogenous human telomerase reverse transcriptase (hTERT) was expressed in tDPSCs. Both cell groups were cultured and their telomerase activities is determined using a telomerase quantification assay. Also examined were the expression of genes involved in proliferation and mineralization such as human alkaline phosphatase (ALP), β-actin, collagen 1 (col-1), core binding factor (cbfa-1), dentin matrix protein (DMP-1), dentin sialophosphoprotein (DSPP), GAPDH, hTERT, osteocalcin (OCN), osteopontin (OPN) as well as oncoproteins involved in senescence (p16, p21 and p53) using RT-PCR. DNA and alkaline phosphatase activity was assayed in both cell groups. CONCLUSIONS These results indicate maintainance of odontoblast-like differentiation characteristics after retroviral transformation with hTERT and suggest a possible link with a reduced p16 expression.
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Affiliation(s)
- Obi Egbuniwe
- Biomaterials and Biomimetics; University College London Cancer Institute; London, UK
| | - Bernadine D Idowu
- Biomaterials and Biomimetics; University College London Cancer Institute; London, UK
| | - Juan M Funes
- University College London Cancer Institute; London, UK
| | - Andrew D Grant
- Wolfson Centre for Age-Related Diseases; University College London Cancer Institute; London, UK
| | - Tara Renton
- Department of Oral Surgery; Dental Institute; King's College London; London, UK
| | - Lucy Di Silvio
- Biomaterials and Biomimetics; University College London Cancer Institute; London, UK
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Witkiewicz AK, Knudsen KE, Dicker AP, Knudsen ES. The meaning of p16(ink4a) expression in tumors: functional significance, clinical associations and future developments. Cell Cycle 2011; 10:2497-503. [PMID: 21775818 DOI: 10.4161/cc.10.15.16776] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The CDKN2A gene is a tumor suppressor that encodes the CDK4/6 inhibitor p16(ink4a). Loss of this tumor suppressor contributes to the bypass of critical senescent signals and is associated with progression to malignant disease. However, the high-level expression of p16(ink4a) in tumors is associated with aggressive subtypes of disease, and in certain clinical settings elevated p16(ink4a) expression is an important determinant for disease prognosis and therapeutic response. These seemingly contradictory facets of p16(ink4a) expression have lead to confusion related to the meaning of this tumor suppression in tumor pathobiology. As reviewed here, the alternative expression of p16(ink4a) represents an ideal marker for considering RB-pathway function, tumor heterogeneity, and novel means for directing therapy.
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Woolthuis CM, de Haan G, Huls G. Aging of hematopoietic stem cells: Intrinsic changes or micro-environmental effects? Curr Opin Immunol 2011; 23:512-7. [PMID: 21664115 DOI: 10.1016/j.coi.2011.05.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 01/06/2023]
Abstract
During development hematopoietic stem cells (HSCs) expand in number and persist throughout life by undergoing self-renewing divisions. Nevertheless, the hematopoietic system does not escape the negative effects of aging, suggesting that self-renewal is not complete. A fundamental issue in stem cell biology relates to such age-dependent loss of stem cell activity. Both stem cell intrinsic factors and extrinsic factors associated with an aging micro-environment could contribute to aging of the hematopoietic system. Recently, changes in the clonal composition of the HSC compartment during aging have been put forward as a key factor. Here, we discuss these recent developments and speculate how they may be of clinical relevance.
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Affiliation(s)
- Carolien M Woolthuis
- Department of Hematology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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