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Baker SJ, Poulikakos PI, Irie HY, Parekh S, Reddy EP. CDK4: a master regulator of the cell cycle and its role in cancer. Genes Cancer 2022; 13:21-45. [PMID: 36051751 PMCID: PMC9426627 DOI: 10.18632/genesandcancer.221] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/17/2022] [Indexed: 11/25/2022] Open
Abstract
The cell cycle is regulated in part by cyclins and their associated serine/threonine cyclin-dependent kinases, or CDKs. CDK4, in conjunction with the D-type cyclins, mediates progression through the G1 phase when the cell prepares to initiate DNA synthesis. Although Cdk4-null mutant mice are viable and cell proliferation is not significantly affected in vitro due to compensatory roles played by other CDKs, this gene plays a key role in mammalian development and cancer. This review discusses the role that CDK4 plays in cell cycle control, normal development and tumorigenesis as well as the current status and utility of approved small molecule CDK4/6 inhibitors that are currently being used as cancer therapeutics.
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Affiliation(s)
- Stacey J. Baker
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
| | - Poulikos I. Poulikakos
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
| | - Hanna Y. Irie
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
| | - Samir Parekh
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
| | - E. Premkumar Reddy
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, Levy Place, NY 10029, USA
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Zhang X, Jiang L, Liu H. Forkhead Box Protein O1: Functional Diversity and Post-Translational Modification, a New Therapeutic Target? DRUG DESIGN DEVELOPMENT AND THERAPY 2021; 15:1851-1860. [PMID: 33976536 PMCID: PMC8106445 DOI: 10.2147/dddt.s305016] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/19/2021] [Indexed: 11/23/2022]
Abstract
Forkhead box protein O1 (FoXO1) is a transcription factor involved in the regulation of a wide variety of physiological process including glucose metabolism, lipogenesis, bone mass, apoptosis, and autophagy. FoXO1 dysfunction is involved in the pathophysiology of various diseases including metabolic diseases, atherosclerosis, and tumors. FoXO1 activity is regulated in response to different physiological or pathogenic conditions by changes in protein expression and post-translational modifications. Various modifications cooperate to regulate FoXO1 activity and FoXO1 target gene transcription. In this review, we summarize how different post-translational modifications regulate FoXO1 physiological function, which may provide new insights for drug design and development.
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Affiliation(s)
- Xiaojun Zhang
- Department of Cardiology, Shandong Rongjun General Hospital, Jinan, 250013, People's Republic of China
| | - Lusheng Jiang
- Department of Emergency, Shandong Rongjun General Hospital, Jinan, 250013, People's Republic of China
| | - Huimin Liu
- Blood Purification Center, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250011, People's Republic of China
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3
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Ferrad M, Ghazzaui N, Issaoui H, Cook-Moreau J, Denizot Y. Mouse Models of c-myc Deregulation Driven by IgH Locus Enhancers as Models of B-Cell Lymphomagenesis. Front Immunol 2020; 11:1564. [PMID: 32793219 PMCID: PMC7390917 DOI: 10.3389/fimmu.2020.01564] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/15/2020] [Indexed: 01/18/2023] Open
Abstract
Chromosomal translocations linking various oncogenes to transcriptional enhancers of the immunoglobulin heavy chain (IgH) locus are often implicated as the cause of B-cell malignancies. Two major IgH transcriptional enhancers have been reported so far. The Eμ enhancer located upstream of the Cμ gene controls early events in B-cell maturation such as VDJ recombination. The 3' regulatory region (3'RR) located downstream from the Cα gene controls late events in B-cell maturation such as IgH transcription, somatic hypermutation, and class switch recombination. Convincing demonstrations of the essential contributions of both Eμ and 3'RR in B-cell lymphomagenesis have been provided by transgenic and knock-in animal models which bring the oncogene c-myc under Eμ/3'RR transcriptional control. This short review summarizes the different mouse models so far available and their interests/limitations for progress in our understanding of human c-myc-induced B-cell lymphomagenesis.
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Affiliation(s)
- Melissa Ferrad
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Nour Ghazzaui
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Hussein Issaoui
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Jeanne Cook-Moreau
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Yves Denizot
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
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4
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Chang H, Zhang X, Li B, Meng X. MAGI2-AS3 suppresses MYC signaling to inhibit cell proliferation and migration in ovarian cancer through targeting miR-525-5p/MXD1 axis. Cancer Med 2020; 9:6377-6386. [PMID: 32681706 PMCID: PMC7476821 DOI: 10.1002/cam4.3126] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/30/2020] [Accepted: 04/24/2020] [Indexed: 12/14/2022] Open
Abstract
Ovarian cancer (OV) is one of the most lethal gynecological malignance in females, and usually diagnosed at advanced stages. Long noncoding RNAs (lncRNAs) exhibit their crucial functions in modulatory mechanisms of cancers. Substantive studies have proven the anti-tumor role of MAGI2-AS3 in multiple cancers, but the physiological functions of MAGI2-AS3 in OV need more detailed explanations. The current study corroborated that overexpression of MAGI2-AS3 executed inhibitory activity in OV via hindering cell proliferation, cell cycle, migration as well as invasion while promoted apoptosis. Moreover MAGI2-AS3 bound with miR-525-5p and negatively regulated the expression of miR-525-5p. Further studies testified that MXD1 was a downstream target of miR-525-5p and the competing relationship between MAGI2-AS3 and MXD1 were confirmed by RNA pull down. Based on the combination between MAX and MYC, we analyzed the effects of MAGI2-AS3 on MXD1 and MYC, unveiling the competing relationship between MXD1 and MYC for binding to MAX. Finally, we constructed rescue assays to certify that MAGI2-AS3 suppressed the course of OV via enhancing MXD1 expression. In summary, MAGI2-AS3 repressed the progression of OV by targeting miR-525-5p/MXD1 axis, offering a novel insight into understanding OV at the molecular level.
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Affiliation(s)
- Hua Chang
- Department of Gynecology, the First Hospital of China Medical University, Shenyang, P.R. China
| | - Xue Zhang
- Department of Gynecology, the First Hospital of China Medical University, Shenyang, P.R. China
| | - Baixue Li
- Department of Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China
| | - Xiangkai Meng
- Department of Gynecology, the First Hospital of China Medical University, Shenyang, P.R. China
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Xia P, Chen J, Liu Y, Fletcher M, Jensen BC, Cheng Z. Doxorubicin induces cardiomyocyte apoptosis and atrophy through cyclin-dependent kinase 2-mediated activation of forkhead box O1. J Biol Chem 2020; 295:4265-4276. [PMID: 32075913 PMCID: PMC7105316 DOI: 10.1074/jbc.ra119.011571] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/17/2020] [Indexed: 12/29/2022] Open
Abstract
Recent clinical investigations indicate that anthracycline-based chemotherapies induce early decline in heart mass in cancer patients. Heart mass decline may be caused by a decrease in cardiac cell number because of increased cell death or by a reduction in cell size because of atrophy. We previously reported that an anthracycline, doxorubicin (DOX), induces apoptotic death of cardiomyocytes by activating cyclin-dependent kinase 2 (CDK2). However, the signaling pathway downstream of CDK2 remains to be characterized, and it is also unclear whether the same pathway mediates cardiac atrophy. Here we demonstrate that DOX exposure induces CDK2-dependent phosphorylation of the transcription factor forkhead box O1 (FOXO1) at Ser-249, leading to transcription of its proapoptotic target gene, Bcl-2-interacting mediator of cell death (Bim). In cultured cardiomyocytes, treatment with the FOXO1 inhibitor AS1842856 or transfection with FOXO1-specific siRNAs protected against DOX-induced apoptosis and mitochondrial damage. Oral administration of AS1842856 in mice abrogated apoptosis and prevented DOX-induced cardiac dysfunction. Intriguingly, pharmacological FOXO1 inhibition also attenuated DOX-induced cardiac atrophy, likely because of repression of muscle RING finger 1 (MuRF1), a proatrophic FOXO1 target gene. In conclusion, DOX exposure induces CDK2-dependent FOXO1 activation, resulting in cardiomyocyte apoptosis and atrophy. Our results identify FOXO1 as a promising drug target for managing DOX-induced cardiotoxicity. We propose that FOXO1 inhibitors may have potential as cardioprotective therapeutic agents during cancer chemotherapy.
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Affiliation(s)
- Peng Xia
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99202-2131
| | - Jingrui Chen
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99202-2131
| | - Yuening Liu
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99202-2131
| | - Maya Fletcher
- Department of Biology, Gonzaga University, Spokane, Washington 99258
| | - Brian C Jensen
- Division of Cardiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7075
| | - Zhaokang Cheng
- Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99202-2131.
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Yang F, Cui Z, Liao Y, Tian R, Fan W, Jin Z, Hu Z, Yao S. FHIT and C-MYC expression in cervical histology and cytology as biomarkers for detecting high-grade intraepithelial neoplasia in human papillomavirus-positive women. Cancer Biomark 2019; 27:303-312. [PMID: 31771040 PMCID: PMC7175930 DOI: 10.3233/cbm-182232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND: The current cervical cancer screening strategies based on Papanicolaou (Pap) and Human papillomavirus (HPV) tests receive great achievement but still exhibit many limitations in clinical practice. Exploring new biomarkers as stratified management method in HPV primary screening is becoming the tendency of current research. METHODS: Immunocytochemistry (ICC) of FHIT and C-MYC were performed on exfoliated cervical cells from 197 eligible high-risk HPV positive women. Mann-Whitney U test, Pearson Chi-Square test, logistic regression analysis and receiver operating characteristic (ROC) curves were used to assess the diagnostic efficiency. RESULTS: ICC staining intensity of FHIT and C-MYC in high-grade cervical intraepithelial neoplasia (CIN) specimens was significantly different from low-grade CIN and normal specimens. Compared with Pap test, ROC analysis of ICC in detecting high-grade CIN resulted in a larger area under the curve (AUC) (0.805 and 0.814 vs 0.723, p< 0.001). FHIT achieved higher sensitivity than Pap test (79.41% vs 66.67%, p= 0.04). Logistic regression analysis of the combination of two biomarkers led to higher AUC value, specificity and PPV than any single biomarker. CONCLUSIONS: The utility of FHIT and C-MYC ICC analysis in cervical exfoliated cells of HPV-positive women displayed superior diagnostic potential and may improve clinical performance of cervical cancer screening.
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Affiliation(s)
| | | | | | | | | | | | - Zheng Hu
- Corresponding authors: Shuzhong Yao, The First Affiliated Hospital of Sun Yat-sen University, Zhongshan Second Road 58, Guangzhou 510080, Guangdong, China. Tel.: +86 136 0283 4127; E-mail: ; Zheng Hu, The First Affiliated Hospital of Sun Yat-sen University, Zhongshan Second Road 58, Guangzhou 510080, Guangdong, China. Tel.: +86 136 3212 0686; E-mail:
| | - Shuzhong Yao
- Corresponding authors: Shuzhong Yao, The First Affiliated Hospital of Sun Yat-sen University, Zhongshan Second Road 58, Guangzhou 510080, Guangdong, China. Tel.: +86 136 0283 4127; E-mail: ; Zheng Hu, The First Affiliated Hospital of Sun Yat-sen University, Zhongshan Second Road 58, Guangzhou 510080, Guangdong, China. Tel.: +86 136 3212 0686; E-mail:
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Non-canonical roles of PFKFB3 in regulation of cell cycle through binding to CDK4. Oncogene 2018; 37:1685-1698. [PMID: 29335521 DOI: 10.1038/s41388-017-0072-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 10/16/2017] [Accepted: 11/08/2017] [Indexed: 01/06/2023]
Abstract
There is growing interest in studying the molecular mechanisms of crosstalk between cancer metabolism and the cell cycle. 6-phosphate fructose-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) is a well-known glycolytic activator that plays an important role in tumorigenesis. We investigated whether PFKFB3 was directly involved in oncogenic signaling networks. Mass Spectrometry showed that PFKFB3 interacts with cyclin-dependent kinase (CDK) 4, which controls the transition from G1 phase to S phase of the cell cycle. Further analysis indicated that lysine 147 was a key site for the binding of PFKBFB3 to CDK4. PFKFB3 binding resulted in the accumulation of CDK4 protein by inhibiting ubiquitin proteasome degradation mediated by the heat shock protein 90-Cdc37-CDK4 complex. The proteasome-dependent degradation of CDK4 was accelerated by disrupting the interaction of PFKFB3 with CDK4 by mutating lysine (147) to alanine. Blocking PFKFB3-CDK4 interaction improved the therapeutic effect of FDA-approved CDK4 inhibitor palbociclib on breast cancer. These findings suggest that PFKFB3 is a hub for coordinating cell cycle and glucose metabolism. Combined targeting of PFKFB3 and CDK4 may be new strategy for breast cancer treatment.
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Tarrado-Castellarnau M, de Atauri P, Tarragó-Celada J, Perarnau J, Yuneva M, Thomson TM, Cascante M. De novo MYC addiction as an adaptive response of cancer cells to CDK4/6 inhibition. Mol Syst Biol 2017; 13:940. [PMID: 28978620 PMCID: PMC5658703 DOI: 10.15252/msb.20167321] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Cyclin‐dependent kinases (CDK) are rational cancer therapeutic targets fraught with the development of acquired resistance by tumor cells. Through metabolic and transcriptomic analyses, we show that the inhibition of CDK4/6 leads to a metabolic reprogramming associated with gene networks orchestrated by the MYC transcription factor. Upon inhibition of CDK4/6, an accumulation of MYC protein ensues which explains an increased glutamine metabolism, activation of the mTOR pathway and blunting of HIF‐1α‐mediated responses to hypoxia. These MYC‐driven adaptations to CDK4/6 inhibition render cancer cells highly sensitive to inhibitors of MYC, glutaminase or mTOR and to hypoxia, demonstrating that metabolic adaptations to antiproliferative drugs unveil new vulnerabilities that can be exploited to overcome acquired drug tolerance and resistance by cancer cells.
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Affiliation(s)
- Míriam Tarrado-Castellarnau
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain
| | - Pedro de Atauri
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain
| | - Josep Tarragó-Celada
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain
| | - Jordi Perarnau
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain
| | | | - Timothy M Thomson
- Institute of Molecular Biology of Barcelona, National Research Council (IBMB-CSIC), Barcelona, Spain
| | - Marta Cascante
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain .,Institute of Biomedicine of Universitat de Barcelona (IBUB) and CSIC-Associated Unit, Barcelona, Spain
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Bahjat M, Guikema JEJ. The Complex Interplay between DNA Injury and Repair in Enzymatically Induced Mutagenesis and DNA Damage in B Lymphocytes. Int J Mol Sci 2017; 18:ijms18091876. [PMID: 28867784 PMCID: PMC5618525 DOI: 10.3390/ijms18091876] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 08/24/2017] [Accepted: 08/29/2017] [Indexed: 11/25/2022] Open
Abstract
Lymphocytes are endowed with unique and specialized enzymatic mutagenic properties that allow them to diversify their antigen receptors, which are crucial sensors for pathogens and mediators of adaptive immunity. During lymphocyte development, the antigen receptors expressed by B and T lymphocytes are assembled in an antigen-independent fashion by ordered variable gene segment recombinations (V(D)J recombination), which is a highly ordered and regulated process that requires the recombination activating gene products 1 & 2 (RAG1, RAG2). Upon activation by antigen, B lymphocytes undergo additional diversifications of their immunoglobulin B-cell receptors. Enzymatically induced somatic hypermutation (SHM) and immunoglobulin class switch recombination (CSR) improves the affinity for antigen and shape the effector function of the humoral immune response, respectively. The activation-induced cytidine deaminase (AID) enzyme is crucial for both SHM and CSR. These processes have evolved to both utilize as well as evade different DNA repair and DNA damage response pathways. The delicate balance between enzymatic mutagenesis and DNA repair is crucial for effective immune responses and the maintenance of genomic integrity. Not surprisingly, disturbances in this balance are at the basis of lymphoid malignancies by provoking the formation of oncogenic mutations and chromosomal aberrations. In this review, we discuss recent mechanistic insight into the regulation of RAG1/2 and AID expression and activity in lymphocytes and the complex interplay between these mutagenic enzymes and DNA repair and DNA damage response pathways, focusing on the base excision repair and mismatch repair pathways. We discuss how disturbances of this interplay induce genomic instability and contribute to oncogenesis.
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Affiliation(s)
- Mahnoush Bahjat
- Department of Pathology, Academic Medical Center, University of Amsterdam; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam 1105 AZ, The Netherlands.
| | - Jeroen E J Guikema
- Department of Pathology, Academic Medical Center, University of Amsterdam; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam 1105 AZ, The Netherlands.
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Abstract
Cancer is characterized by uncontrolled tumour cell proliferation resulting from aberrant activity of various cell cycle proteins. Therefore, cell cycle regulators are considered attractive targets in cancer therapy. Intriguingly, animal models demonstrate that some of these proteins are not essential for proliferation of non-transformed cells and development of most tissues. By contrast, many cancers are uniquely dependent on these proteins and hence are selectively sensitive to their inhibition. After decades of research on the physiological functions of cell cycle proteins and their relevance for cancer, this knowledge recently translated into the first approved cancer therapeutic targeting of a direct regulator of the cell cycle. In this Review, we focus on proteins that directly regulate cell cycle progression (such as cyclin-dependent kinases (CDKs)), as well as checkpoint kinases, Aurora kinases and Polo-like kinases (PLKs). We discuss the role of cell cycle proteins in cancer, the rationale for targeting them in cancer treatment and results of clinical trials, as well as the future therapeutic potential of various cell cycle inhibitors.
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Affiliation(s)
- Tobias Otto
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02215, USA
- Department of Internal Medicine III, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Piotr Sicinski
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02215, USA
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NF-κB and AKT signaling prevent DNA damage in transformed pre-B cells by suppressing RAG1/2 expression and activity. Blood 2015; 126:1324-35. [PMID: 26153519 DOI: 10.1182/blood-2015-01-621623] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 07/01/2015] [Indexed: 01/16/2023] Open
Abstract
In developing lymphocytes, expression and activity of the recombination activation gene protein 1 (RAG1) and RAG2 endonuclease complex is tightly regulated to ensure ordered recombination of the immunoglobulin genes and to avoid genomic instability. Aberrant RAG activity has been implicated in the generation of secondary genetic events in human B-cell acute lymphoblastic leukemias (B-ALLs), illustrating the oncogenic potential of the RAG complex. Several layers of regulation prevent collateral genomic DNA damage by restricting RAG activity to the G1 phase of the cell cycle. In this study, we show a novel pathway that suppresses RAG expression in cycling-transformed mouse pre-B cells and human pre-B B-ALL cells that involves the negative regulation of FOXO1 by nuclear factor κB (NF-κB). Inhibition of NF-κB in cycling pre-B cells resulted in upregulation of RAG expression and recombination activity, which provoked RAG-dependent DNA damage. In agreement, we observe a negative correlation between NF-κB activity and the expression of RAG1, RAG2, and TdT in B-ALL patients. Our data suggest that targeting NF-κB in B-ALL increases the risk of RAG-dependent genomic instability.
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