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Palanichamy JK, Tran TM, King JK, Katzman S, Ritter AJ, Sharma G, Tso C, Contreras JR, Fernando TR, Sanford JR, Rao DS. Distinct oncogenic phenotypes in hematopoietic specific deletions of Trp53. Sci Rep 2023; 13:7490. [PMID: 37160922 PMCID: PMC10169790 DOI: 10.1038/s41598-023-33949-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 04/21/2023] [Indexed: 05/11/2023] Open
Abstract
Loss of function in the tumor suppressor gene TP53 is the most common alteration seen in human cancer. In mice, P53 deletion in all cells leads predominantly to the development of T-cell lymphomas, followed by B-cell lymphomas, sarcomas and teratomas. In order to dissect the role of P53 in the hematopoietic system, we generated and analyzed two different mouse models deficient for P53. A pan-hematopoietic P53 deletion mouse was created using Vav1-Cre based deletion; and a B-cell-specific deletion mouse was created using a CD19-Cre based deletion. The Vav1-P53CKO mice predominantly developed T-cell malignancies in younger mice, and myeloid malignancies in older mice. In T-cell malignancies, there was accelerated thymic cell maturation with overexpression of Notch1 and its downstream effectors. CD19-P53CKO mice developed marginal zone expansion in the spleen, followed by marginal zone lymphoma, some of which progressed to diffuse large B-cell lymphomas. Interestingly, marginal zone and diffuse large B-cell lymphomas had a unique gene expression signature characterized by activation of the PI3K pathway, compared with wild type marginal zone or follicular cells of the spleen. This study demonstrates lineage specific P53 deletion leading to distinct phenotypes secondary to unique gene expression programs set in motion.
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Affiliation(s)
| | - Tiffany M Tran
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, USA
- Molecular, Cellular and Integrative Physiology Graduate Program, UCLA, Los Angeles, USA
| | | | - Sol Katzman
- Center for Biomolecular Science & Engineering, UCSC, Santa Cruz, USA
| | - Alexander J Ritter
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, UCSC, Santa Cruz, USA
| | - Gunjan Sharma
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Christine Tso
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, USA
| | - Jorge R Contreras
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, USA
| | | | - Jeremy R Sanford
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, UCSC, Santa Cruz, USA
| | - Dinesh S Rao
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, USA.
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, USA.
- Broad Stem Cell Research Center, UCLA, Los Angeles, USA.
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 650 Charles E Young Drive, Los Angeles, CA, 90095, USA.
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Szpotkowska J, Swiatkowska A, Ciesiołka J. Length and secondary structure of the 5' non-coding regions of mouse p53 mRNA transcripts - mouse as a model organism for p53 gene expression studies. RNA Biol 2018; 16:25-41. [PMID: 30518296 DOI: 10.1080/15476286.2018.1556084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Transcription initiation sites of Trp53 gene in mice were determined using the 5'RACE method. Based on sequence alignment of the 5'-terminal regions of p53 mRNA in mammals, the site for the most abundant transcript turned out to be essentially identical with that determined for human TP53 gene and slightly differed for the longest transcripts, in mice and humans. Secondary structures of the 5' -terminal regions of the shorter, most abundant and the longest mouse transcripts were determined in vitro and the shorter transcript was also mapped in transfected mouse cells. For the first time, secondary structure models of the 5' terminus of two mouse p53 mRNAs were proposed. Comparing these models with the conservativeness of the nucleotide sequence of the 5'-terminal region of mRNA in mouse and other mammals, the possible function of the selected structural domains of this region was discussed. To elucidate the translation mechanisms, the two studied mRNAs were translated in the presence of an increasing concentration of the cap analog. For the longest transcript, the data suggested that IRES element(s) was/were involved in translation initiation. Additionally, changes in p53 synthesis under genotoxic and endoplasmic reticulum stress conditions in mouse cells were analyzed.
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Affiliation(s)
- Joanna Szpotkowska
- a Polish Academy of Sciences , Institute of Bioorganic Chemistry , Poznan , Poland
| | - Agata Swiatkowska
- a Polish Academy of Sciences , Institute of Bioorganic Chemistry , Poznan , Poland
| | - Jerzy Ciesiołka
- a Polish Academy of Sciences , Institute of Bioorganic Chemistry , Poznan , Poland
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3
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Li YF, Altman RB. Systematic target function annotation of human transcription factors. BMC Biol 2018; 16:4. [PMID: 29325558 PMCID: PMC5795274 DOI: 10.1186/s12915-017-0469-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 12/06/2017] [Indexed: 01/03/2023] Open
Abstract
Background Transcription factors (TFs), the key players in transcriptional regulation, have attracted great experimental attention, yet the functions of most human TFs remain poorly understood. Recent capabilities in genome-wide protein binding profiling have stimulated systematic studies of the hierarchical organization of human gene regulatory network and DNA-binding specificity of TFs, shedding light on combinatorial gene regulation. We show here that these data also enable a systematic annotation of the biological functions and functional diversity of TFs. Result We compiled a human gene regulatory network for 384 TFs covering the 146,096 TF–target gene (TF–TG) relationships, extracted from over 850 ChIP-seq experiments as well as the literature. By integrating this network of TF–TF and TF–TG relationships with 3715 functional concepts from six sources of gene function annotations, we obtained over 9000 confident functional annotations for 279 TFs. We observe extensive connectivity between TFs and Mendelian diseases, GWAS phenotypes, and pharmacogenetic pathways. Further, we show that TFs link apparently unrelated functions, even when the two functions do not share common genes. Finally, we analyze the pleiotropic functions of TFs and suggest that the increased number of upstream regulators contributes to the functional pleiotropy of TFs. Conclusion Our computational approach is complementary to focused experimental studies on TF functions, and the resulting knowledge can guide experimental design for the discovery of unknown roles of TFs in human disease and drug response. Electronic supplementary material The online version of this article (doi:10.1186/s12915-017-0469-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yong Fuga Li
- Stanford Genome Technology Center, Stanford, CA, USA. .,Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Present address: Department of Bioinformatics, Illumina Inc., San Diego, CA, USA.
| | - Russ B Altman
- Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Department of Genetics, Stanford University, Stanford, CA, USA.
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Shen Y, Xu K, Yuan Z, Guo J, Zhao H, Zhang X, Zhao L, Qing Y, Li H, Pan W, Jia B, Zhao HY, Wei HJ. Efficient generation of P53 biallelic knockout Diannan miniature pigs via TALENs and somatic cell nuclear transfer. J Transl Med 2017; 15:224. [PMID: 29100547 PMCID: PMC5670695 DOI: 10.1186/s12967-017-1327-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 10/27/2017] [Indexed: 11/13/2022] Open
Abstract
Background Pigs have many features that make them attractive as biomedical models for various diseases, including cancer. P53 is an important tumor suppressor gene that exerts a central role in protecting cells from oncogenic transformation and is mutated in a large number of human cancers. P53 mutations occur in almost every type of tumor and in over 50% of all tumors. In a recent publication, pigs with a mutated P53 gene were generated that resulted in lymphoma and renal and osteogenic tumors. However, approximately 80% of human tumors have dysfunctional P53. A P53-deficient pig model is still required to elucidate. Methods Transcription activator-like effector nucleases (TALENs) were designed to target porcine P53 exon 4. The targeting activity was evaluated using a luciferase SSA recombination assay. P53 biallelic knockout (KO) cell lines were established from single-cell colonies of fetal fibroblasts derived from Diannan miniature pigs followed by electroporation with TALENs plasmids. One cell line was selected as the donor cell line for somatic cell nuclear transfer (SCNT) for the generation of P53 KO pigs. P53 KO stillborn fetuses and living piglets were obtained. Gene typing of the collected cloned individuals was performed by T7EI assay and sequencing. Fibroblast cells from Diannan miniature piglets with a P53 biallelic knockout or wild type were analyzed for the P53 response to doxorubicin treatment by confocal microscopy and western blotting. Results The luciferase SSA recombination assay revealed that the targeting activities of the designed TALENs were 55.35-fold higher than those of the control. Eight cell lines (8/19) were mutated for P53, and five of them were biallelic knockouts. One of the biallelic knockout cell lines was selected as nuclear donor cells for SCNT. The cloned embryos were transferred into five recipient gilts, three of them becoming pregnant. Five live fetuses were obtained from one surrogate by caesarean section after 38 days of gestation for genotyping. Finally, six live piglets and one stillborn piglet were collected from two recipients by caesarean section. Sequencing analyses of the target site confirmed the P53 biallelic knockout in all fetuses and piglets, consistent with the genotype of the donor cells. The qPCR analysis showed that the expression of the P53 mRNA had significant reduction in various tissues of the knockout piglets. Furthermore, confocal microscopy and western blotting analyses demonstrated that the fibroblast cells of Diannan miniature piglets with a P53 biallelic knockout were defective in mediating DNA damage when incubated with doxorubicin. Conclusion TALENs combined with SCNT was successfully used to generate P53 KO Diannan miniature pigs. Although these genetically engineered Diannan miniature pigs had no tumorigenic signs, the P53 gene was dysfunctional. We believe that these pigs will provide powerful new resources for preclinical oncology and basic cancer research. Electronic supplementary material The online version of this article (10.1186/s12967-017-1327-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Youfeng Shen
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Kaixiang Xu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China
| | - Zaimei Yuan
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Jianxiong Guo
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China
| | - Heng Zhao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Xuezeng Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,Key Laboratory Animal Nutrition and Feed of Yunnan Province, Yunnan Agricultural University, Kunming, 650201, China
| | - Lu Zhao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,Key Laboratory Animal Nutrition and Feed of Yunnan Province, Yunnan Agricultural University, Kunming, 650201, China
| | - Yubo Qing
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Honghui Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Weirong Pan
- College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Baoyu Jia
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Hong-Ye Zhao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.
| | - Hong-Jiang Wei
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China. .,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China. .,Key Laboratory Animal Nutrition and Feed of Yunnan Province, Yunnan Agricultural University, Kunming, 650201, China.
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Gil VS, Bhagat G, Howell L, Zhang J, Kim CH, Stengel S, Vega F, Zelent A, Petrie K. Deregulated expression of HDAC9 in B cells promotes development of lymphoproliferative disease and lymphoma in mice. Dis Model Mech 2016; 9:1483-1495. [PMID: 27799148 PMCID: PMC5200892 DOI: 10.1242/dmm.023366] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 10/21/2016] [Indexed: 12/11/2022] Open
Abstract
Histone deacetylase 9 (HDAC9) is expressed in B cells, and its overexpression has been observed in B-lymphoproliferative disorders, including B-cell non-Hodgkin lymphoma (B-NHL). We examined HDAC9 protein expression and copy number alterations in primary B-NHL samples, identifying high HDAC9 expression among various lymphoma entities and HDAC9 copy number gains in 50% of diffuse large B-cell lymphoma (DLBCL). To study the role of HDAC9 in lymphomagenesis, we generated a genetically engineered mouse (GEM) model that constitutively expressed an HDAC9 transgene throughout B-cell development under the control of the immunoglobulin heavy chain (IgH) enhancer (Eμ). Here, we report that the Eμ-HDAC9 GEM model develops splenic marginal zone lymphoma and lymphoproliferative disease (LPD) with progression towards aggressive DLBCL, with gene expression profiling supporting a germinal center cell origin, as is also seen in human B-NHL tumors. Analysis of Eμ-HDAC9 tumors suggested that HDAC9 might contribute to lymphomagenesis by altering pathways involved in growth and survival, as well as modulating BCL6 activity and p53 tumor suppressor function. Epigenetic modifications play an important role in the germinal center response, and deregulation of the B-cell epigenome as a consequence of mutations and other genomic aberrations are being increasingly recognized as important steps in the pathogenesis of a variety of B-cell lymphomas. A thorough mechanistic understanding of these alterations will inform the use of targeted therapies for these malignancies. These findings strongly suggest a role for HDAC9 in B-NHL and establish a novel GEM model for the study of lymphomagenesis and, potentially, preclinical testing of therapeutic approaches based on histone deacetylase inhibitors. Summary: This study demonstrates that aberrant expression of HDAC9 in B cells promotes development of lymphoproliferative disease and lymphoma through altering expression of genes involved in the cell cycle and survival, and modulating the activity of key B-lineage factors such as BCL6 and p53.
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Affiliation(s)
- Veronica S Gil
- Division of Clinical Studies, Institute of Cancer Research, London SM2 5NG, UK
| | - Govind Bhagat
- Department of Pathology & Cell Biology, Columbia University Medical Center, New York, NY 10032, USA.,Department of Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032, USA
| | - Louise Howell
- Division of Molecular Pathology, Institute of Cancer Research, London SM2 5NG, UK
| | - Jiyuan Zhang
- Department of Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032, USA.,Institute for Cancer Genetics, Columbia University, New York, NY 10032, USA
| | - Chae H Kim
- Division of Hematopathology, Sylvester Cancer Center, University of Miami, Miami, FL 33136, USA
| | - Sven Stengel
- Division of Molecular Pathology, Institute of Cancer Research, London SM2 5NG, UK
| | - Francisco Vega
- Division of Hematopathology, Sylvester Cancer Center, University of Miami, Miami, FL 33136, USA
| | - Arthur Zelent
- Department of Medicine, Sylvester Comprehensive Cancer Center, University of Miami, Miami, FL 33136, USA
| | - Kevin Petrie
- Department of Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
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6
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Reed SM, Hagen J, Muniz VP, Rosean TR, Borcherding N, Sciegienka S, Goeken JA, Naumann PW, Zhang W, Tompkins VS, Janz S, Meyerholz DK, Quelle DE. NIAM-deficient mice are predisposed to the development of proliferative lesions including B-cell lymphomas. PLoS One 2014; 9:e112126. [PMID: 25393878 PMCID: PMC4231569 DOI: 10.1371/journal.pone.0112126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 10/12/2014] [Indexed: 01/10/2023] Open
Abstract
Nuclear Interactor of ARF and Mdm2 (NIAM, gene designation Tbrg1) is a largely unstudied inhibitor of cell proliferation that helps maintain chromosomal stability. It is a novel activator of the ARF-Mdm2-Tip60-p53 tumor suppressor pathway as well as other undefined pathways important for genome maintenance. To examine its predicted role as a tumor suppressor, we generated NIAM mutant (NIAMm/m) mice homozygous for a β-galactosidase expressing gene-trap cassette in the endogenous gene. The mutant mice expressed significantly lower levels of NIAM protein in tissues compared to wild-type animals. Fifty percent of aged NIAM deficient mice (14 to 21 months) developed proliferative lesions, including a uterine hemangioma, pulmonary papillary adenoma, and a Harderian gland adenoma. No age-matched wild-type or NIAM+/m heterozygous animals developed lesions. In the spleen, NIAMm/m mice had prominent white pulp expansion which correlated with enhanced increased reactive lymphoid hyperplasia and evidence of systemic inflammation. Notably, 17% of NIAM mutant mice had splenic white pulp features indicating early B-cell lymphoma. This correlated with selective expansion of marginal zone B cells in the spleens of younger, tumor-free NIAM-deficient mice. Unexpectedly, basal p53 expression and activity was largely unaffected by NIAM loss in isolated splenic B cells. In sum, NIAM down-regulation in vivo results in a significant predisposition to developing benign tumors or early stage cancers. These mice represent an outstanding platform for dissecting NIAM's role in tumorigenesis and various anti-cancer pathways, including p53 signaling.
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Affiliation(s)
- Sara M. Reed
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
- Medical Scientist Training Program, University of Iowa, Iowa City, Iowa, United States of America
| | - Jussara Hagen
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
| | - Viviane P. Muniz
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, Iowa, United States of America
| | - Timothy R. Rosean
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, Iowa, United States of America
| | - Nick Borcherding
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Sebastian Sciegienka
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
| | - J. Adam Goeken
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Paul W. Naumann
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Weizhou Zhang
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, Iowa, United States of America
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Van S. Tompkins
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Siegfried Janz
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, Iowa, United States of America
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - David K. Meyerholz
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
| | - Dawn E. Quelle
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
- Medical Scientist Training Program, University of Iowa, Iowa City, Iowa, United States of America
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, Iowa, United States of America
- Department of Pathology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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7
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Seo H, Kim W, Lee J, Youn B. Network-based approaches for anticancer therapy (Review). Int J Oncol 2013; 43:1737-44. [PMID: 24085339 DOI: 10.3892/ijo.2013.2114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/23/2013] [Indexed: 12/16/2022] Open
Abstract
Cancer is a complex disease resulting from alterations of multiple signaling networks. Cancer networks have been identified as scale-free networks and may contain a functionally important key player called a hub that is linked to a large number of interactors. Since a hub can serve as a biological marker in a given network, targeting the hub could be an effective strategy for enhancing the efficacy of cancer treatment. Chemotherapies and radiotherapies are generally used to treat tumors not amenable to resection, and target single or multiple molecules associated with hubs. However, these therapies may unexpectedly induce the resistance of cancer cells to drugs and radiation. Cancer cells can overcome therapy-induced damage via the activation of back-up signaling pathways and flexible modulation of affected networks. These activities are considered to be the main reasons for chemoresistance and radioresistance, and subsequent failure of cancer therapies. Much effort is required to identify the key molecules that control the modulation of signaling networks in response to drugs and radiation. Network-based therapy that affects network flexibility, including rewired network structures and hub molecules in these networks, could minimize the occurrence of side-effects and be a promising strategy for enhancing the therapeutic efficacy of cancer treatments. This review is intended to offer an overview of current research efforts including ones focused on cancer-associated complex networks, their modulation in response to cancer therapy, and further strategies targeting networks that may improve cancer treatment efficacy.
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Affiliation(s)
- Hyunjeong Seo
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
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Conditional inactivation of p53 in mature B cells promotes generation of nongerminal center-derived B-cell lymphomas. Proc Natl Acad Sci U S A 2013; 110:2934-9. [PMID: 23382223 DOI: 10.1073/pnas.1222570110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The p53 tumor suppressor exerts a central role in protecting cells from oncogenic transformation. Accordingly, the p53 gene is mutated in a large number of human cancers. In mice, germ-line inactivation of p53 confers strong predisposition to development of different types of malignancies, but the early onset of thymic lymphomas in the majority of the animals prevents detailed studies of tumorigenesis in other tissues. Here, we use the Cre/Lox approach to inactivate p53 in mature B cells in mice (referred to as "CP" B cells) and find that such p53 inactivation results in the routine development of IgM-positive CP peripheral B-cell lymphomas. The CP lymphomas generally appear to arise, even in mice subjected to immunization protocols to activate germinal center reaction, from naive B cells that had not undergone immunoglobulin (Ig) heavy chain gene class switching or somatic hypermutation. In contrast to thymic lymphomas that arise in p53-deficient mice, which generally lack clonal translocations, nearly all analyzed CP B-cell tumors carried clonal translocations. However, in contrast to spontaneous translocations in other mouse B-cell tumor models, CP B-cell tumor translocations were not recurrent and did not involve Ig loci. Therefore, CP tumors might provide models for human lymphomas lacking Ig translocations, such as splenic marginal zone B-cell lymphoma or Waldenstrom macroglobulinemia. Our studies indicate that deletion of p53 is sufficient to trigger transformation of mature B cells and support the notion that p53 deficiency may allow accumulation of oncogenic translocations in B cells.
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