851
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Kaindl U, Morak M, Portsmouth C, Mecklenbräuker A, Kauer M, Zeginigg M, Attarbaschi A, Haas OA, Panzer-Grümayer R. Blocking ETV6/RUNX1-induced MDM2 overexpression by Nutlin-3 reactivates p53 signaling in childhood leukemia. Leukemia 2014; 28:600-8. [PMID: 24240203 PMCID: PMC3948158 DOI: 10.1038/leu.2013.345] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/03/2013] [Accepted: 10/07/2013] [Indexed: 01/16/2023]
Abstract
ETV6/RUNX1 (E/R) is the most common fusion gene in childhood acute lymphoblastic leukemia. It is responsible for the initiation of leukemia but also indispensable for disease maintenance and propagation, although its function in these latter processes is less clear. We therefore investigated the effects of the perceived p53 pathway alterations in model cell lines and primary leukemias and, in particular, how E/R upregulates MDM2, the predominant negative regulator of p53. We found that E/R transactivates MDM2 in both p53(+/+) and p53(-/-) HCT116 cells by binding to promoter-inherent RUNX1 motifs, which indicates that this activation occurs in a direct and p53-independent manner. Treatment of E/R-positive leukemic cell lines with Nutlin-3, a small molecule that inhibits the MDM2/p53 interaction, arrests their cell cycle and induces apoptosis. These phenomena concur with a p53-induced expression of p21, pro-apoptotic BAX and PUMA, as well as caspase 3 activation and poly ADP-ribose polymerase cleavage. The addition of DNA-damaging and p53-activating chemotherapeutic drugs intensifies apoptosis. Moreover, Nutlin-3 exposure leads to an analogous p53 accumulation and apoptotic surge in E/R-positive primary leukemic cells. Our findings clarify the role of p53 signaling in E/R-positive leukemias and outline the potential basis for its therapeutic exploitation in this setting.
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Affiliation(s)
- U Kaindl
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - M Morak
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - C Portsmouth
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - A Mecklenbräuker
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - M Kauer
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - M Zeginigg
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
| | - A Attarbaschi
- St Anna Kinderspital, Medical University Vienna, Vienna, Austria
| | - O A Haas
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
- St Anna Kinderspital, Medical University Vienna, Vienna, Austria
| | - R Panzer-Grümayer
- St Anna Kinderkrebsforschung, Children's Cancer Research Institute, Vienna, Austria
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852
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Liu J, Zhang C, Feng Z. Tumor suppressor p53 and its gain-of-function mutants in cancer. Acta Biochim Biophys Sin (Shanghai) 2014; 46:170-9. [PMID: 24374774 DOI: 10.1093/abbs/gmt144] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Tumor suppressor p53 plays a pivotal role in tumor suppression. p53 is the most frequently mutated gene in cancer. As a transcription factor, p53 mainly exerts its role in tumor suppression through transcriptional regulation of its downstream target genes. Thus, p53 and its target genes form a complex p53 signaling pathway to regulate a wide variety of biological processes to prevent tumorigenesis. Recent studies have revealed that in addition to apoptosis, cell cycle arrest and senescence, p53's functions in the regulation of energy metabolism and anti-oxidant defense contribute significantly to its role in tumor suppression. Studies further show that many tumor-associated mutant p53 proteins not only lose tumor suppressive functions of wild-type p53, but also gain new oncogenic activities that are independent of wild-type p53, including promoting tumor cell proliferation, survival, metabolic changes, angiogenesis, and metastasis, which are defined as mutant p53 gain-of-function. The frequent loss of wild-type p53 function and the gain-of-function of mutant p53 in human tumors make p53 an extremely attractive target for cancer therapy. Different strategies and many small-molecule drugs are being developed for the p53-based tumor therapy. Here, we review the mechanisms of p53 in tumor suppression and gain-of-function mutant p53 in tumor development, as well as the recent advances in the development of the p53-based tumor therapy.
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Affiliation(s)
- Juan Liu
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903, USA
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853
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Zhuo X, Ren J, Li D, Wu Y, Zhou Q. MDM2 SNP309 variation increases cervical cancer risk among Asians. Tumour Biol 2014; 35:5331-7. [PMID: 24532430 DOI: 10.1007/s13277-014-1695-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 01/26/2014] [Indexed: 01/20/2023] Open
Abstract
MDM2 T309G polymorphism has been suggested to be a risk factor for a number of cancers. The association of MDM2 T309G genetic variation with cervical cancer risk remains inconclusive. In the present study, we aimed to get a more confidential result by conducting a quantitative meta-analysis. Relevant literature up to October 2013 was searched and screened. Essential information was rigorously extracted for data pooling and analyzing, and then, separate analyses on ethnicity and source of controls were also performed. As a result, four articles including five case-control studies were selected. The overall data failed to show a significant association between MDM2 T309G polymorphism and cervical cancer risk (GG vs TT: odds ratio (OR)=1.31; 95 % confidence interval (CI)=0.55-3.13; dominant model: OR=1.22; 95 % CI=0.65-2.31; recessive model: OR=1.45; 95 % CI=0.79-2.65). However, in the subgroup analysis about ethnicity, increased cancer risk could be shown among Asians (GG vs TT: OR=2.15; 95 % CI=1.03-4.51; recessive model: OR=2.01; 95 % CI=1.32-3.06). In conclusion, the results of the present study suggest that homozygous GG alleles of MDM2 T309G polymorphism might be a risk factor for cervical cancer among Asians. Further studies are needed get a more definitive conclusion.
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Affiliation(s)
- Xianlu Zhuo
- Department of Radiation Oncology, Chongqing Cancer Institute, Chongqing, China,
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854
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Okada N, Lin CP, Ribeiro MC, Biton A, Lai G, He X, Bu P, Vogel H, Jablons DM, Keller AC, Wilkinson JE, He B, Speed TP, He L. A positive feedback between p53 and miR-34 miRNAs mediates tumor suppression. Genes Dev 2014; 28:438-50. [PMID: 24532687 PMCID: PMC3950342 DOI: 10.1101/gad.233585.113] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
As bona fide p53 transcriptional targets, miR-34 microRNAs (miRNAs) exhibit frequent alterations in many human tumor types and elicit multiple p53 downstream effects upon overexpression. Unexpectedly, miR-34 deletion alone fails to impair multiple p53-mediated tumor suppressor effects in mice, possibly due to the considerable redundancy in the p53 pathway. Here, we demonstrate that miR-34a represses HDM4, a potent negative regulator of p53, creating a positive feedback loop acting on p53. In a Kras-induced mouse lung cancer model, miR-34a deficiency alone does not exhibit a strong oncogenic effect. However, miR-34a deficiency strongly promotes tumorigenesis when p53 is haploinsufficient, suggesting that the defective p53-miR-34 feedback loop can enhance oncogenesis in a specific context. The importance of the p53/miR-34/HDM4 feedback loop is further confirmed by an inverse correlation between miR-34 and full-length HDM4 in human lung adenocarcinomas. In addition, human lung adenocarcinomas generate an elevated level of a short HDM4 isoform through alternative polyadenylation. This short HDM4 isoform lacks miR-34-binding sites in the 3' untranslated region (UTR), thereby evading miR-34 regulation to disable the p53-miR-34 positive feedback. Taken together, our results elucidated the intricate cross-talk between p53 and miR-34 miRNAs and revealed an important tumor suppressor effect generated by this positive feedback loop.
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Affiliation(s)
- Nobuhiro Okada
- Molecular and Cell Biology Department, University of California at Berkeley, Berkeley, California 94705, USA
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855
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Nguyen TA, Menendez D, Resnick MA, Anderson CW. Mutant TP53 posttranslational modifications: challenges and opportunities. Hum Mutat 2014; 35:738-55. [PMID: 24395704 DOI: 10.1002/humu.22506] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/02/2014] [Indexed: 12/13/2022]
Abstract
The wild-type (WT) human p53 (TP53) tumor suppressor can be posttranslationally modified at over 60 of its 393 residues. These modifications contribute to changes in TP53 stability and in its activity as a transcription factor in response to a wide variety of intrinsic and extrinsic stresses in part through regulation of protein-protein and protein-DNA interactions. The TP53 gene frequently is mutated in cancers, and in contrast to most other tumor suppressors, the mutations are mostly missense often resulting in the accumulation of mutant (MUT) protein, which may have novel or altered functions. Most MUT TP53s can be posttranslationally modified at the same residues as in WT TP53. Strikingly, however, codons for modified residues are rarely mutated in human tumors, suggesting that TP53 modifications are not essential for tumor suppression activity. Nevertheless, these modifications might alter MUT TP53 activity and contribute to a gain-of-function leading to increased metastasis and tumor progression. Furthermore, many of the signal transduction pathways that result in TP53 modifications are altered or disrupted in cancers. Understanding the signaling pathways that result in TP53 modification and the functions of these modifications in both WT TP53 and its many MUT forms may contribute to more effective cancer therapies.
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Affiliation(s)
- Thuy-Ai Nguyen
- Chromosome Stability Section, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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856
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Pan LZ, Ahn DG, Sharif T, Clements D, Gujar SA, Lee PWK. The NAD+ synthesizing enzyme nicotinamide mononucleotide adenylyltransferase 2 (NMNAT-2) is a p53 downstream target. Cell Cycle 2014; 13:1041-8. [PMID: 24552824 DOI: 10.4161/cc.28128] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
NAD(+) metabolism plays key roles not only in energy production but also in diverse cellular physiology. Aberrant NAD(+) metabolism is considered a hallmark of cancer. Recently, the tumor suppressor p53, a major player in cancer signaling pathways, has been implicated as an important regulator of cellular metabolism. This notion led us to examine whether p53 can regulate NAD(+) biosynthesis in the cell. Our search resulted in the identification of nicotinamide mononucleotide adenylyltransferase 2 (NMNAT-2), a NAD(+) synthetase, as a novel downstream target gene of p53. We show that NMNAT-2 expression is induced upon DNA damage in a p53-dependent manner. Two putative p53 binding sites were identified within the human NMNAT-2 gene, and both were found to be functional in a p53-dependent manner. Furthermore, knockdown of NMNAT-2 significantly reduces cellular NAD(+) levels and protects cells from p53-dependent cell death upon DNA damage, suggesting an important functional role of NMNAT-2 in p53-mediated signaling. Our demonstration that p53 modulates cellular NAD(+) synthesis is congruent with p53's emerging role as a key regulator of metabolism and related cell fate.
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Affiliation(s)
- Lu-Zhe Pan
- Department of Microbiology and Immunology; Dalhousie University; Halifax, Nova Scotia, Canada
| | - Dae-Gyun Ahn
- Department of Microbiology and Immunology; Dalhousie University; Halifax, Nova Scotia, Canada
| | - Tanveer Sharif
- Department of Microbiology and Immunology; Dalhousie University; Halifax, Nova Scotia, Canada
| | - Derek Clements
- Department of Pathology; Dalhousie University; Halifax, Nova Scotia, Canada
| | - Shashi A Gujar
- Department of Microbiology and Immunology; Dalhousie University; Halifax, Nova Scotia, Canada; Strategy & Organizational Performance; IWK Health Centre; Halifax, Nova Scotia, Canada
| | - Patrick W K Lee
- Department of Microbiology and Immunology; Dalhousie University; Halifax, Nova Scotia, Canada; Department of Pathology; Dalhousie University; Halifax, Nova Scotia, Canada
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857
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Wang L, Liu Z, Jing P, Shao L, Chen L, He X, Gong W. Effects of murine double minute 2 polymorphisms on the risk and survival of osteosarcoma: a systemic review and meta-analysis. Tumour Biol 2014; 35:1649-52. [PMID: 24122202 DOI: 10.1007/s13277-013-1227-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 09/16/2013] [Indexed: 01/24/2023] Open
Abstract
Murine double minute 2 (MDM2) plays an important role in the carcinogenesis of many cancers including osteosarcoma. We performed a systemic review and meta-analysis to assess the effects of MDM2 polymorphisms on osteosarcoma risk and survival of patients with osteosarcoma. PubMed, Web of Science, and Wanfang databases were searched for eligible studies on the associations of MDM2 polymorphisms with osteosarcoma risk and survival of patients with osteosarcoma. Pooled odds ratio (OR) or hazard ratio (HR) with 95 % confidence intervals (95 % CIs) was used to assess the effects of MDM2 polymorphisms on osteosarcoma risk and survival of patients with osteosarcoma. Overall, MDM2 rs2279744 polymorphism was associated with a risk of osteosarcoma (allele model, OR = 1.60, 95 % CI 1.23-2.07, P < 0.001; codominant model, OR = 2.47, 95 % CI 1.46-4.19, P = 0.001; recessive model, OR = 2.13, 95 % CI 1.32-3.46, P = 0.002; dominant model, OR = 1.61, 95 % CI 1.12-2.33, P = 0.01). MDM2 rs1690916 polymorphism was also associated with a risk of osteosarcoma (OR = 0.60, 95 % CI 0.46-0.77, P < 0.001). However, MDM2 rs2279744 polymorphism was not associated with the overall survival of patients with osteosarcoma (codominant model, HR = 1.01, 95 % CI 0.53-1.91, P = 0.98; recessive model, HR = 1.07, 95 % CI 0.54-2.11, P = 0.85; dominant model, HR = 1.04, 95 % CI 0.65-1.66, P = 0.87). The meta-analysis suggests that MDM2 polymorphisms have some effects on the risk of osteosarcoma but have no effect on the survival of patients with osteosarcoma. Future studies are needed to further assess the effects of MDM2 polymorphisms on the risk and survival of osteosarcoma.
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858
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Sun T, Cui J. A plausible model for bimodal p53 switch in DNA damage response. FEBS Lett 2014; 588:815-21. [PMID: 24486906 DOI: 10.1016/j.febslet.2014.01.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 12/26/2013] [Accepted: 01/13/2014] [Indexed: 01/10/2023]
Abstract
p53 is a tumor suppressor and the p53 dynamics displays stimulus dependent patterns. Recent evidence suggests a bimodal p53 switch in cell fate decision. However, no theoretical studies have been proposed to investigate bimodal p53 induction. Here we constructed a model and showed that MDM2-p53 mRNA binding might contribute to bimodal p53 switch through an intrinsic positive feedback loop. Lower damage favored pulsing while monotonic increasing was generated with higher damage. Bimodal p53 dynamics was largely influenced by cellular MDM2 and elevated p53/MDM2 ratios with increasing etoposide favor mono-ubiquitination. Our model replicated recent experiments and provided potential insights into dynamic mechanisms of bimodal switch.
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Affiliation(s)
- Tingzhe Sun
- School of Life Sciences, AnQing Normal University, AnQing 246011, Anhui, PR China.
| | - Jun Cui
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, PR China.
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859
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Hock AK, Vousden KH. The role of ubiquitin modification in the regulation of p53. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:137-49. [DOI: 10.1016/j.bbamcr.2013.05.022] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/16/2013] [Accepted: 05/23/2013] [Indexed: 01/09/2023]
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860
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Levav-Cohen Y, Goldberg Z, Tan KH, Alsheich-Bartok O, Zuckerman V, Haupt S, Haupt Y. The p53-Mdm2 loop: a critical juncture of stress response. Subcell Biochem 2014; 85:161-86. [PMID: 25201194 DOI: 10.1007/978-94-017-9211-0_9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The presence of a functional p53 protein is a key factor for the proper suppression of cancer development. A loss of p53 activity, by mutations or inhibition, is often associated with human malignancies. The p53 protein integrates various stress signals into a growth restrictive cellular response. In this way, p53 eliminates cells with a potential to become cancerous. Being a powerful decision maker, it is imperative that p53 will be activated properly, efficiently and temporarily in response to stress. Equally important is that p53 activation will be extinguished upon recovery from stress, and that improper activation of p53 will be avoided. Failure to achieve these aims is likely to have catastrophic consequences for the organism. The machinery that governs this tight regulation is largely based on the major inhibitor of p53, Mdm2, which both blocks p53 activities and promotes its destabilization. The interplay between p53 and Mdm2 involves a complex network of positive and negative feedback loops. Relief from Mdm2 suppression is required for p53 to be stabilized and activated in response to stress. Protection from Mdm2 entails a concerted action of modifying enzymes and partner proteins. The association of p53 with the PML-nuclear bodies may provide an infrastructure in which this complex regulatory network can be orchestrated. In this chapter we use examples to illustrate the regulatory machinery that drives this network.
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Affiliation(s)
- Yaara Levav-Cohen
- Lautenberg Center, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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861
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Nag S, Zhang X, Srivenugopal K, Wang MH, Wang W, Zhang R. Targeting MDM2-p53 interaction for cancer therapy: are we there yet? Curr Med Chem 2014; 21:553-74. [PMID: 24180275 PMCID: PMC6690199 DOI: 10.2174/09298673113206660325] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/02/2013] [Accepted: 10/22/2013] [Indexed: 11/22/2022]
Abstract
Inactivation of the tumor suppressor p53 and/or overexpression of the oncogene MDM2 frequently occur in human cancers, and are associated with poor prognosis, advanced forms of the disease, and chemoresistance. MDM2, the major negative regulator of p53, induces p53 degradation and inactivates its tumor suppressing activity. In turn, p53 regulates MDM2 expression. This MDM2-p53 negative feedback loop has been widely studied and presents an attractive target for cancer therapy, with a few of the inhibitors of this interaction already having advanced into clinical trials. Additionally, there is an increasing interest in understanding MDM2's p53-independent activities in carcinogenesis and cancer progression, which may also have implications for cancer therapy. This review aims to highlight the various roles that the MDM2-p53 interaction plays in cancer, the p53 independent oncogenic activities of MDM2 and the various strategies that may be used to target MDM2 and the MDM2-p53 interaction. We will summarize the major preclinical and clinical evidences of MDM2 inhibitors for human cancer treatment and make suggestions to further improve efficacy and safety of this interesting class of cancer therapeutics.
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Affiliation(s)
- S. Nag
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - X. Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - K.S. Srivenugopal
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - M.-H. Wang
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - W. Wang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - R. Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
- Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
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862
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Suzuki K, Yamashita S. Radiation-Induced Bystander Response: Mechanism and Clinical Implications. Adv Wound Care (New Rochelle) 2014; 3:16-24. [PMID: 24761341 DOI: 10.1089/wound.2013.0468] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 06/21/2013] [Indexed: 01/05/2023] Open
Abstract
Significance: Absorption of energy from ionizing radiation (IR) to the genetic material in the cell gives rise to damage to DNA in a dose-dependent manner. There are two types of DNA damage; by a high dose (causing acute or deterministic effects) and by a low dose (related to chronic or stochastic effects), both of which induce different health effects. Among radiation effects, acute cutaneous radiation syndrome results from cell killing as a consequence of high-dose exposure. Recent advances: Recent advances in radiation biology and oncology have demonstrated that bystander effects, which are emerged in cells that have never been exposed, but neighboring irradiated cells, are also involved in radiation effects. Bystander effects are now recognized as an indispensable component of tissue response related to deleterious effects of IR. Critical issues: Evidence has indicated that nonapoptotic premature senescence is commonly observed in various tissues and organs. Senesced cells were found to secrete various proteins, including cytokines, chemokines, and growth factors, most of which are equivalent to those identified as bystander factors. Secreted factors could trigger cell proliferation, angiogenesis, cell migration, inflammatory response, etc., which provide a tissue microenvironment assisting tissue repair and remodeling. Future directions: Understandings of the mechanisms and physiological relevance of radiation-induced bystander effects are quite essential for the beneficial control of wound healing and care. Further studies should extend our knowledge of the mechanisms of bystander effects and mode of cell death in response to IR.
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Affiliation(s)
- Keiji Suzuki
- Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Shunichi Yamashita
- Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
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863
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Abstract
The tumor suppressor p53 plays a central role in anti-tumorigenesis and cancer therapy. It has been described as "the guardian of the genome", because it is essential for conserving genomic stability by preventing mutation, and its mutation and inactivation are highly related to all human cancers. Two important p53 regulators, MDM2 and MDMX, inactivate p53 by directly inhibiting its transcriptional activity and mediating its ubiquitination in a feedback fashion, as their genes are also the transcriptional targets of p53. On account of the importance of the p53-MDM2-MDMX loop in the initiation and development of wild type p53-containing tumors, intensive studies over the past decade have been aiming to identify small molecules or peptides that could specifically target individual protein molecules of this pathway for developing better anti-cancer therapeutics. In this chapter, we review the approaches for screening and discovering efficient and selective MDM2 inhibitors with emphasis on the most advanced synthetic small molecules that interfere with the p53-MDM2 interaction and are currently on Phase I clinical trials. Other therapeutically useful strategies targeting this loop, which potentially improve the prospects of cancer therapy and prevention, will also be discussed briefly.
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Affiliation(s)
- Qi Zhang
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, 1430 Tulane Ave, Louisiana, LA, 70112, USA
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864
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Abstract
Discovered in 1987 and 1997 respectively, Mdm2 and MdmX represent two critical cellular regulators of the p53 tumor suppressor. This chapter reviews each from initial discovery to our current understanding of their deregulation in human cancer with a focus on how each regulator impacts p53 function. While p53 independent activities of Mdm2 and MdmX are noted the reader is directed to other reviews on this topic. The chapter concludes with an examination of the various mechanisms of Mdm-deregulation and an assessment of the current therapeutic approaches to target Mdm2 and MdmX overexpression.
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865
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Choe YJ, Lee SY, Ko KW, Shin SJ, Kim HS. Nutlin-3 induces HO-1 expression by activating JNK in a transcription-independent manner of p53. Int J Oncol 2013; 44:761-8. [PMID: 24366007 DOI: 10.3892/ijo.2013.2227] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/19/2013] [Indexed: 11/06/2022] Open
Abstract
A recent study reported that p53 can induce HO-1 by directly binding to the putative p53 responsive element in the HO-1 promoter. In this study, we report that nutlin-3, a small molecule antagonist of HDM2, induces the transcription of HO-1 in a transcription-independent manner of p53. Nutlin-3 induced HO-1 expression at the level of transcription in human cancer cells such as U2OS and RKO cells. This induction of HO-1 did not occur in SAOS cells in which p53 was mutated and was prevented by knocking down the p53 protein using p53 siRNA transfection, but not by PFT-α, an inhibitor of the transcriptional activity of p53. Accompanying HO-1 expression, nutlin-3 stimulated the accumulation of ROS and the phosphorylation of MAPKs such as JNK, p38 MAPK and ERK1/2. Nutlin-3-induced HO-1 expression was suppressed by TEMPO, a ROS scavenger, and chemical inhibitors of JNK and p38 MAPK but not ERK1/2. In addition, nutlin‑3-induced phosphorylation of JNK but not p38 MAPK was inhibited by TEMPO. Notably, the levels of nutlin-3-induced ROS were correlated with the mitochondrial translocation of p53 and this induction was prevented by PFT-μ, an inhibitor of the mitochondrial translocation of p53. Consistent with the effect of the ROS scavenger and MAPK inhibitors, PFT-μ reduced HO-1 expression and the phosphorylation of JNK induced by nutlin-3. In the experiments of analyzing cell death, the knockdown of HO-1 augmented nutlin-3-induced apoptosis. Collectively, these results suggest that nutlin-3 induces HO-1 expression via the activation of both JNK which is dependent on ROS generated by p53 translocated to the mitochondria and p38 MAPK which appears to be stimulated by a ROS-independent mechanism, and this HO-1 induction may inhibit nutlin-3-induced apoptosis, constituting a negative feedback loop of p53-induced apoptosis.
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Affiliation(s)
- Yun-Jeong Choe
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Sun-Young Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Kyung Won Ko
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Seok Joon Shin
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Ho-Shik Kim
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
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866
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Abstract
The genetics of angioimmunoblastic T-cell lymphoma (AITL) are very poorly understood. We defined the mutational landscape of AITL across 219 genes in 85 cases from the United States and Europe. We identified ≥2 mutations in 34 genes, nearly all of which were not previously implicated in AITL. These included loss-of-function mutations in TP53 (n = 4), ETV6 (n = 3), CCND3 (n = 2), and EP300 (n = 5), as well as gain-of-function mutations in JAK2 (n = 2) and STAT3 (n = 4). TET2 was mutated in 65 (76%) AITLs, including 43 that harbored 2 or 3 TET2 mutations. DNMT3A mutations occurred in 28 (33%) AITLs; 100% of these also harbored TET2 mutations (P < .0001). Seventeen AITLs harbored IDH2 R172 substitutions, including 15 with TET2 mutations. In summary, AITL is characterized by high frequencies of overlapping mutations in epigenetic modifiers and targetable mutations in a subset of cases.
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867
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Lawasut P, Groen RWJ, Dhimolea E, Richardson PG, Anderson KC, Mitsiades CS. Decoding the pathophysiology and the genetics of multiple myeloma to identify new therapeutic targets. Semin Oncol 2013; 40:537-48. [PMID: 24135398 DOI: 10.1053/j.seminoncol.2013.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In recent years, significant progress has been achieved in the characterization of the transcriptional profiles, gene mutations and structural chromosomal lesions in myeloma cells. These studies have identified many candidate therapeutic targets, which are recurrently deregulated in myeloma cells. However, these targets do not appear, at least individually, to represent universal driver(s) of this disease. Furthermore, evaluation of these recurrent lesions does not suggest that they converge to a single molecular pathway. Detailed integration of molecular and functional data for these candidate targets and pathways will hopefully dissect which of them play more critical roles for each of the different individual molecular defined subtypes of this disease. This review focuses on how recent updates in our understanding of myeloma pathogenesis and molecular characterization may impact ongoing and future efforts to develop new therapeutics for this disease.
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Affiliation(s)
- Panisinee Lawasut
- Department of Medical Oncology, Dana-Farber Cancer Institute, and Department of Medicine, Harvard Medical School, Boston, MA; Division of Hematology, Department of Medicine, Faculty of Medicine, King Chulalongkorn Memorial Hospital and Chulalongkorn University, Thai Red Cross Society, Bangkok, Thailand
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868
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Hsp90 inhibitor BIIB021 enhances triptolide-induced apoptosis of human T-cell acute lymphoblastic leukemia cells in vitro mainly by disrupting p53-MDM2 balance. Acta Pharmacol Sin 2013; 34:1545-53. [PMID: 24241349 DOI: 10.1038/aps.2013.124] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/02/2013] [Indexed: 01/02/2023] Open
Abstract
AIM To investigate the effects of BIIB021, an inhibitor of heat shock protein 90 (Hsp90) alone or in combination with triptolide (TPL) on T-cell acute lymphoblastic leukemia (T-ALL) and the mechanisms of action. METHODS Human T-ALL cells line Molt-4 was examined. The cell viability was measured using MTT assay. Apoptotic cells were studied with Hoechst 33258 staining. Cell apoptosis and cell cycle were analyzed using flow cytometry with Annexin V/PI staining and PI staining, respectively. The levels of multiple proteins, including Akt, p65, CDK4/6, p18, Bcl-2 family proteins, MDM2, and p53, were examined with Western blotting. The level of MDM2 mRNA was determined using RT-PCR. RESULTS Treatment of Molt-4 cells with BIIB021 (50-800 nmol/L) inhibited the cell growth in a dose-dependent manner (the IC50 value was 384.6 and 301.8 nmol/L, respectively, at 48 and 72 h). BIIB021 dose-dependently induced G0/G1 phase arrest, followed by apoptosis of Molt-4 cells. Furthermore, BIIB021 increased the expression of p18, decreased the expression of CDK4/6, and activated the caspase pathway in Molt-4 cells. Moreover, BIIB021 (50-400 nmol/L) dose-dependently decreased the phospho-MDM2 and total MDM2 protein levels, but slightly increased the phospho-p53 and total p53 protein levels, whereas TPL (5-40 nmol/L) dose-dependently enhanced p53 activation without affecting MDM2 levels. Co-treatment with BIIB021 and TPL showed synergic inhibition on Molt-4 cell growth. The co-treatment disrupted p53-MDM2 balance, thus markedly enhanced p53 activation. In addition, the co-treatment increased the expression of Bak and Bim, followed by increased activation of caspase-9. CONCLUSION The combination of BIIB021 and TPL may provide a novel strategy for treating T-ALL by overcoming multiple mechanisms of apoptosis resistance.
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869
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Sonnemann J, Marx C, Becker S, Wittig S, Palani CD, Krämer OH, Beck JF. p53-dependent and p53-independent anticancer effects of different histone deacetylase inhibitors. Br J Cancer 2013; 110:656-67. [PMID: 24281001 PMCID: PMC3915118 DOI: 10.1038/bjc.2013.742] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/28/2013] [Accepted: 10/30/2013] [Indexed: 12/17/2022] Open
Abstract
Background: Histone deacetylase inhibitors (HDACi) are promising antineoplastic agents, but their precise mechanisms of actions are not well understood. In particular, the relevance of p53 for HDACi-induced effects has not been fully elucidated. We investigated the anticancer effects of four structurally distinct HDACi, vorinostat, entinostat, apicidin and valproic acid, using isogenic HCT-116 colon cancer cell lines differing in p53 status. Methods: Effects were assessed by MTT assay, flow-cytometric analyses of propidium iodide uptake, mitochondrial depolarisation and cell-cycle distribution, as well as by gene expression profiling. Results: Vorinostat was equally effective in p53 wild-type and null cells, whereas entinostat was less effective in p53 null cells. Histone deacetylase inhibitors treatment suppressed the expression of MDM2 and increased the abundance of p53. Combination treatments showed that vorinostat enhanced the cytotoxic activity of TRAIL and bortezomib, independent of the cellular p53 status. Investigations into the effects of an inhibitor of the sirtuin class of HDAC, tenovin-1, revealed that tenovin-1-mediated cell death hinged on p53. Conclusion: These results demonstrate that vorinostat activates p53, but does not require p53 for inducing its anticancer action. Yet they also demonstrate that entinostat-induced cytotoxic effects partially depend on p53, indicating that different HDACi have a different requirement for p53.
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Affiliation(s)
- J Sonnemann
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - C Marx
- Department of Biochemistry, Center for Molecular Biomedicine, Institute for Biochemistry and Biophysics, Friedrich Schiller University of Jena, Jena, Germany
| | - S Becker
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - S Wittig
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - C D Palani
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
| | - O H Krämer
- Department of Biochemistry, Center for Molecular Biomedicine, Institute for Biochemistry and Biophysics, Friedrich Schiller University of Jena, Jena, Germany
| | - J F Beck
- Department of Paediatric Haematology and Oncology, Jena University Hospital, Children's Clinic, Jena, Germany
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870
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Van Maerken T, Rihani A, Van Goethem A, De Paepe A, Speleman F, Vandesompele J. Pharmacologic activation of wild-type p53 by nutlin therapy in childhood cancer. Cancer Lett 2013; 344:157-65. [PMID: 24262662 DOI: 10.1016/j.canlet.2013.11.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/20/2013] [Accepted: 11/10/2013] [Indexed: 02/08/2023]
Abstract
A peculiar feature of several types of childhood cancer is that loss-of-function mutations of the TP53 (p53) tumor suppressor gene are uncommon, in contrast to many adult tumors. As p53 needs to be inactivated in order for tumor cells to survive and thrive, pediatric tumors typically make use of other mechanisms to keep p53 in check. One of the critical negative regulators of p53 is the MDM2 oncoprotein. Many anticancer drug development efforts in the past decade have therefore been devoted to the discovery and optimization of small molecules that selectively disrupt the interaction between MDM2 and p53, which could provide, in principle, a potent means to restore p53 function in tumor cells with wild-type p53. The nutlins are the class of selective inhibitors of the p53-MDM2 interaction that are currently most advanced in their clinical development. We review here the preclinical data that support the potential therapeutic use of nutlin drugs in the treatment of various pediatric tumors, including neuroblastoma, retinoblastoma, osteosarcoma, Ewing's sarcoma, rhabdomyosarcoma, medulloblastoma, and childhood acute lymphoblastic leukemia.
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Affiliation(s)
- Tom Van Maerken
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - Ali Rihani
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Alan Van Goethem
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Anne De Paepe
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Frank Speleman
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Jo Vandesompele
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
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871
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Hitzenbichler F, Stoehr CG, Rogenhofer M, Wieland WF, Ruemmele P, Hartmann A, Stoehr R. Mdm2 SNP309 G-variant is associated with invasive growth of human urinary bladder cancer. Pathobiology 2013; 81:53-9. [PMID: 24217660 DOI: 10.1159/000355976] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 09/24/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Human mouse double minute 2 (Mdm2) is essential in degrading p53 by acting as an ubiquitin ligase and therefore plays a vital role in cell cycle and survival. The G-variant of the Mdm2 SNP309, which is located within the promoter of the Mdm2 gene, increases expression of Mdm2 and thereby inhibits the p53 pathway. Several studies have investigated the influence of this SNP on disease risk and onset of various malignancies. The impact of Mdm2 SNP309 on bladder cancer is still to be established due to inconsistent data. METHODS In a case-control study we determined the distribution of Mdm2 SNP309 genotypes in 111 patients with an early-onset bladder cancer (diagnosis <45 years of age), in 113 consecutive bladder cancer patients and in a control group consisting of 140 patients without any malignancy. RESULTS There was no significant association between the allelic distribution of the Mdm2 SNP309 and tumor risk, early onset, gender or grade of the tumor. According to tumor stage we found a significant difference in the distribution of the Mdm2 SNP309 between patients with noninvasive and invasive (≥pT1) tumor growth (p = 0.016). In patients with invasive tumors a significant increase of the G allele was found (T/T vs. T/G + G/G; p = 0.023; OR 2.203, 95% CI 1.111-4.369). CONCLUSION These data indicate that the G-variant of the Mdm2 SNP309 might influence the development of a more aggressive tumor phenotype in patients with bladder cancer without affecting the overall tumor risk.
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Affiliation(s)
- Florian Hitzenbichler
- Department of Internal Medicine I, Caritas St. Josef Medical Center, University of Regensburg, Regensburg, Germany
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872
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Wickramasekera NT, Das GM. Tumor suppressor p53 and estrogen receptors in nuclear-mitochondrial communication. Mitochondrion 2013; 16:26-37. [PMID: 24177747 DOI: 10.1016/j.mito.2013.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 10/04/2013] [Accepted: 10/22/2013] [Indexed: 01/09/2023]
Abstract
Several gene transcription regulators considered solely localized within the nuclear compartment are being reported to be present in the mitochondria as well. There is growing interest in the role of mitochondria in regulating cellular metabolism in normal and disease states. Various findings demonstrate the importance of crosstalk between nuclear and mitochondrial genomes, transcriptomes, and proteomes in regulating cellular functions. Both tumor suppressor p53 and estrogen receptor (ER) were originally characterized as nuclear transcription factors. In addition to their individual roles as regulators of various genes, these two proteins interact resulting in major cellular consequences. In addition to its nuclear role, p53 has been localized to the mitochondria where it executes various transcription-independent functions. Likewise, ERs are reported to be present in mitochondria; however their functional roles remain to be clearly defined. In this review, we provide an integrated view of the current knowledge of nuclear and mitochondrial p53 and ERs and how it relates to normal and pathological physiology.
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Affiliation(s)
- Nadi T Wickramasekera
- Department of Pharmacology and Therapeutics, Center for Genetics and Pharmacology, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY 14263, United States
| | - Gokul M Das
- Department of Pharmacology and Therapeutics, Center for Genetics and Pharmacology, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY 14263, United States.
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873
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Bista M, Wolf S, Khoury K, Kowalska K, Huang Y, Wrona E, Arciniega M, Popowicz GM, Holak TA, Dömling A. Transient protein states in designing inhibitors of the MDM2-p53 interaction. Structure 2013; 21:2143-51. [PMID: 24207125 DOI: 10.1016/j.str.2013.09.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/10/2013] [Accepted: 09/13/2013] [Indexed: 11/28/2022]
Abstract
Reactivation of p53 by release of the functional protein from its inhibition by MDM2 provides an efficient, nongenotoxic approach to a wide variety of cancers. We present the cocrystal structures of two complexes of MDM2 with inhibitors based on 6-chloroindole scaffolds. Both molecules bound to a distinct conformational state of MDM2 with nM-μM affinities. In contrast to other structurally characterized antagonists, which mimic three amino acids of p53 (Phe19, Trp23, and Leu26), the compounds induced an additional hydrophobic pocket on the MDM2 surface and unveiled a four-point binding mode. The enlarged interaction interface of the inhibitors resulted in extension of small molecules binding toward the "lid" segment of MDM2 (residues 19-23)--a nascent element that interferes with p53 binding. As supported by protein engineering and molecular dynamics studies, employing these unstable elements of MDM2 provides an efficient and yet unexplored alternative in development of MDM2-p53 association inhibitors.
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Affiliation(s)
- Michal Bista
- Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
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874
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Leão M, Gomes S, Soares J, Bessa C, Maciel C, Ciribilli Y, Pereira C, Inga A, Saraiva L. Novel simplified yeast-based assays of regulators of p53-MDMX interaction and p53 transcriptional activity. FEBS J 2013; 280:6498-507. [PMID: 24119020 DOI: 10.1111/febs.12552] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/05/2013] [Accepted: 09/25/2013] [Indexed: 11/27/2022]
Abstract
Yeast has proven to be an efficient model system for functional and pharmacological studies of the p53 tumour suppressor protein. In this work, the human p53-MDMX regulatory pathway was reconstituted in yeast. Additionally, by using the known inhibitor of p53-MDMX interaction, SJ-172550, the efficacy of a simplified yeast-based screening assay to search for inhibitors of p53-MDMX interaction is demonstrated for the first time. Moreover, further insights on p53 transcriptional activity in yeast are provided. In particular, it is shown that the reported wild-type (wt) p53-induced yeast growth inhibition and cell cycle arrest is associated with actin depolarization and with an increase of actin mRNA and protein expression levels. The increase of actin protein levels was not observed with the p53 R273H mutant (a loss of function p53 mutation hotspot) and was further intensified with the toxic p53 V122A mutant (reported to exhibit higher transcriptional activity than wt p53 for selected p53 target sequences). Moreover, it is shown that the wt p53-induced actin protein levels are modulated by natural (MDM2 and MDMX) and chemical (pifithrin-α, nutlin-3a and SJ-172550) regulators of p53 activity. Furthermore, wt p53 could stimulate transcription from a minimal promoter containing a fragment of the ACT1 upstream sequence. Thus, ACT1 is proposed as a putative endogenous p53 target gene. This finding may open the way for the development of simpler yeast p53 transactivation assays, not based on artificial reporter constructs, for the analysis of the impact of mutants, cofactors and small molecules on p53 transcriptional activity.
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Affiliation(s)
- Mariana Leão
- REQUIMTE, Laboratório de Microbiologia, Departamento de Ciências Biológicas, Universidade do Porto, Portugal
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875
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Hoffman Y, Bublik DR, Pilpel Y, Oren M. miR-661 downregulates both Mdm2 and Mdm4 to activate p53. Cell Death Differ 2013; 21:302-9. [PMID: 24141721 DOI: 10.1038/cdd.2013.146] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 09/10/2013] [Accepted: 09/16/2013] [Indexed: 01/25/2023] Open
Abstract
The p53 pathway is pivotal in tumor suppression. Cellular p53 activity is subject to tight regulation, in which the two related proteins Mdm2 and Mdm4 have major roles. The delicate interplay between the levels of Mdm2, Mdm4 and p53 is crucial for maintaining proper cellular homeostasis. microRNAs (miRNAs) are short non-coding RNAs that downregulate the level and translatability of specific target mRNAs. We report that miR-661, a primate-specific miRNA, can target both Mdm2 and Mdm4 mRNA in a cell type-dependent manner. miR-661 interacts with Mdm2 and Mdm4 RNA within living cells. The inhibitory effect of miR-661 is more prevalent on Mdm2 than on Mdm4. Interestingly, the predicted miR-661 targets in both mRNAs reside mainly within Alu elements, suggesting a primate-specific mechanism for regulatory diversification during evolution. Downregulation of Mdm2 and Mdm4 by miR-661 augments p53 activity and inhibits cell cycle progression in p53-proficient cells. Correspondingly, low miR-661 expression correlates with bad outcome in breast cancers that typically express wild-type p53. In contrast, the miR-661 locus tends to be amplified in tumors harboring p53 mutations, and miR-661 promotes migration of cells derived from such tumors. Thus, miR-661 may either suppress or promote cancer aggressiveness, depending on p53 status.
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Affiliation(s)
- Y Hoffman
- 1] Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel [2] Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - D R Bublik
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Y Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - M Oren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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876
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USP7 inhibitor P22077 inhibits neuroblastoma growth via inducing p53-mediated apoptosis. Cell Death Dis 2013; 4:e867. [PMID: 24136231 PMCID: PMC3920959 DOI: 10.1038/cddis.2013.400] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 08/23/2013] [Accepted: 09/02/2013] [Indexed: 01/06/2023]
Abstract
Neuroblastoma (NB) is a common pediatric cancer and contributes to more than 15% of all pediatric cancer-related deaths. Unlike adult tumors, recurrent somatic mutations in NB, such as tumor protein 53 (p53) mutations, occur with relative paucity. In addition, p53 downstream function is intact in NB cells with wild-type p53, suggesting that reactivation of p53 may be a viable therapeutic strategy for NB treatment. Herein, we report that the ubiquitin-specific protease 7 (USP7) inhibitor, P22077, potently induces apoptosis in NB cells with an intact USP7-HDM2-p53 axis but not in NB cells with mutant p53 or without human homolog of MDM2 (HDM2) expression. In this study, we found that P22077 stabilized p53 by inducing HDM2 protein degradation in NB cells. P22077 also significantly augmented the cytotoxic effects of doxorubicin (Dox) and etoposide (VP-16) in NB cells with an intact USP7-HDM2-p53 axis. Moreover, P22077 was found to be able to sensitize chemoresistant LA-N-6 NB cells to chemotherapy. In an in vivo orthotopic NB mouse model, P22077 significantly inhibited the xenograft growth of three NB cell lines. Database analysis of NB patients shows that high expression of USP7 significantly predicts poor outcomes. Together, our data strongly suggest that targeting USP7 is a novel concept in the treatment of NB. USP7-specific inhibitors like P22077 may serve not only as a stand-alone therapy but also as an effective adjunct to current chemotherapeutic regimens for treating NB with an intact USP7-HDM2-p53 axis.
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877
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Abstract
MDM2 and MDMX are homologous proteins that bind to p53 and regulate its activity. Both contain three folded domains and ~70% intrinsically disordered regions. Previous detailed structural and biophysical studies have concentrated on the isolated folded domains. The N-terminal domains of both exhibit high affinity for the disordered N-terminal of p53 (p53TAD) and inhibit its transactivation function. Here, we have studied full-length MDMX and found a ~100-fold weaker affinity for p53TAD than does its isolated N-terminal domain. We found from NMR spectroscopy and binding studies that MDMX (but not MDM2) contains a conserved, disordered self-inhibitory element that competes intramolecularly for binding with p53TAD. This motif, which we call the WWW element, is centered around residues Trp200 and Trp201. Deletion or mutation of the element increased binding affinity of MDMX to that of the isolated N-terminal domain level. The self-inhibition of MDMX implies a regulatory, allosteric mechanism of its activity. MDMX rests in a latent state in which its binding activity with p53TAD is masked by autoinhibition. Activation of MDMX would require binding to a regulatory protein. The inhibitory function of the WWW element may explain the oncogenic effects of an alternative splicing variant of MDMX that does not contain the WWW element and is found in some aggressive cancers.
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878
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Liu J, Yang S, Wang Z, Chen X, Zhang Z. Ubiquitin ligase A20 regulates p53 protein in human colon epithelial cells. J Biomed Sci 2013; 20:74. [PMID: 24099634 PMCID: PMC4021182 DOI: 10.1186/1423-0127-20-74] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 10/06/2013] [Indexed: 01/13/2023] Open
Abstract
Background Intestinal polyps may further develop into colon cancer; the pathogenesis is not clear. The p53 gene is an important anti-cancer gene in the body, which is suppressed in cancer. The ubiquitin E3 ligase A20 (A20) plays a role in regulating the activities of epithelial cells. This study was designed to investigate the role of the colon polyp epithelium-derived A20 in the pathogenesis of colon cancer. Results Eighty-eight colon cancer patients and 136 colon polyp patients were recruited into this study. Human colon cancer tissue, the epithelium of adenomas polyp and hyperplastic polyp showed high levels of A20, which had a positive correlation with the cancerous tendency of colon polyps. The levels of A20 were much higher in the adenomas and hyperplastic polyps than that in the inflammatory polyps; the latter showed less cancerous tendency. A20 bound p53 to form complexes in colon cancer tissue and colon polyps. Over expression of A20 suppresses P53 protein levels in the HEK293 cells. Conclusions A20 may play an important role in the cancerous tendency of colon polyposis.
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Affiliation(s)
- Jing Liu
- Department of Digestive Endoscopy, Division of South Building, Chinese PLA general hospital, Beijing 100853, China.
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879
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Muthusami S, Prabakaran DS, An Z, Yu JR, Park WY. EGCG suppresses Fused Toes Homolog protein through p53 in cervical cancer cells. Mol Biol Rep 2013; 40:5587-96. [PMID: 24065519 DOI: 10.1007/s11033-013-2660-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 09/14/2013] [Indexed: 01/22/2023]
Abstract
The anticarcinogenic actions of epigallocatechin-3-gallate (EGCG), one of the main ingredients of green tea, against various cancer types including cervical cancer are well documented. Studies pertaining to the exact molecular mechanism by which EGCG induces cancer cell growth inhibition needs to be investigated extensively. In the present study, we observed a stupendous dose dependent reduction in the protein expression of Fused Toes Homolog (FTS) after treatment with EGCG at 1, 10, 25 and 50 μM. Further, we were interested in finding out whether the decrease in the protein expression of FTS was due to decreased mRNA synthesis. Real time reverse transcriptase polymerase chain reaction results revealed a similar dose dependent reduction in the FTS mRNA after EGCG treatment. Chromatin immunoprecipitation analysis revealed the interaction between p53 and the promoter region of FTS. A dose dependent increase in this interaction was evidenced at 25 and 50 μM EGCG treatment. p53 silencing increased the expression of FTS and also decreased the reduction in the levels of FTS expression after EGCG treatment. The decrease in the levels of FTS was more significant at 25 and 50 μM and is associated with reduced physical interaction of FTS with Akt, phosphorylation of Akt and survival of HeLa cells. Collectively, these results conclude that EGCG induced anti-proliferative action in the cervical cancer cell involves reduced mRNA expression of FTS through p53.
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Affiliation(s)
- Sridhar Muthusami
- Department of Radiation Oncology, College of Medicine, Chungbuk National University, Cheongju, 361-763, South Korea
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880
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Wu B, Guo D, Guo Y. Association between p53 Arg72Pro polymorphism and thyroid cancer risk: a meta-analysis. Tumour Biol 2013; 35:561-5. [DOI: 10.1007/s13277-013-1078-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/05/2013] [Indexed: 12/20/2022] Open
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881
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Yuan XW, Wang DM, Hu Y, Tang YN, Shi WW, Guo XJ, Song JG. Hepatocyte nuclear factor 6 suppresses the migration and invasive growth of lung cancer cells through p53 and the inhibition of epithelial-mesenchymal transition. J Biol Chem 2013; 288:31206-16. [PMID: 24022481 DOI: 10.1074/jbc.m113.480285] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Epithelial-mesenchymal transition plays an important role in many patho-physiological processes, including cancer invasion and metastatic progression. Hepatocyte nuclear factor 6 (HNF6) has been known to be an important factor for both physiological and pathological functions in liver and pancreas. However, its role in EMT and lung cancer progression remains unidentified. We observed that HNF6 level can be down-regulated by TGF-β1 in human lung cancer cells. Knockdown of HNF6 induced EMT and increased cell migration. In contrast, ectopically expression of HNF6 inhibited cell migration and attenuated TGF-β1-induced EMT. The data suggest that HNF6 plays a role in maintaining epithelial phenotype, which suppresses EMT. HNF6 also inhibits both colony formation and proliferation of lung cancer cells. It pronouncedly reduced the formation of tumor xenografts in nude mice. In addition, HNF6 can activate the promoter activity of p53 by directly binding to a specific region of its promoter and therefore increase the protein level of tumor suppressor p53. p53 knockdown induced EMT and increased cell migration, whereas the opposite effect was generated by p53 overexpression. p53 knockdown also inhibited the effect of HNF6 on EMT and cell migration, indicating that p53 is required for the functions of HNF6 herein. Moreover, there is a high positive correlation among the expression levels of HNF6, p53, and E-cadherin in human lung cancer cells and tissues. The data suggest that HNF6 inhibits EMT, cell migration, and invasive growth through a mechanism involving the transcriptional activation of p53.
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Affiliation(s)
- Xin-Wang Yuan
- From the Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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882
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Fahrer J, Rausch J, Barth H. A cell-permeable fusion protein based on Clostridium botulinum C2 toxin for delivery of p53 tumorsuppressor into cancer cells. PLoS One 2013; 8:e72455. [PMID: 24039769 PMCID: PMC3764140 DOI: 10.1371/journal.pone.0072455] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 07/18/2013] [Indexed: 01/09/2023] Open
Abstract
Genetically engineered bacterial protein toxins are attractive systems for delivery of exogenous proteins into the cytosol of mammalian cells. The binary C2 toxin from C. botulinum has emerged as powerful delivery vehicle, which rests on its binding/translocation component C2IIa and the genetically modified adaptor domain C2IN that act in concert to trigger cell uptake. The p53 tumor suppressor protein has a crucial function in suppressing carcinogenesis and is frequently inactivated by diverse mechanisms in human tumor cells. Therefore, we constructed a C2IN-p53 fusion protein, which is internalized into cancer cells by C2IIa. To this end, the C2IN-p53 fusion construct was overexpressed in E. coli with good solubility, purified by heparin affinity chromatography and protein identity was confirmed by immunoblotting. We demonstrated that the fusion protein is capable of binding to the p53 consensus-DNA with high affinity in a p53-specific manner in vitro. Next, the internalization of C2IN-p53 was monitored in HeLa cells by cell fractionation and immunoblot analysis, which revealed a C2IIa-mediated translocation of the fusion protein into the cytosol. The uptake was also shown in A549 and Saos-2 cells with similar efficiency. These findings were further corroborated by confocal immunofluorescence analyses of C2IN-p53/C2IIa-treated HeLa and A549 cells, displaying predominantly cytoplasmic localization of the fusion construct.
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Affiliation(s)
- Jörg Fahrer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany ; Institute of Toxicology, University Medical Center Mainz, Mainz, Germany
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883
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Correlation between the Expression Level of the MDM Homolog Gene and Inflammatory Lesions in Different Populations of the Model Organism Mytilus Galloprovincialis from Polluted Areas of the Gulf of Naples (Southern Italy). EUR J INFLAMM 2013. [DOI: 10.1177/1721727x1301100326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In vertebrate species, the MDM2 and MDM4 gene paralogs negatively regulate the activity of p53 family members and are involved in the development of a number of tumor types. Comparative genomic analyses have shown the presence of a single mdm homolog gene in invertebrates; its interaction with p53 and its involvement in tumor pathogenesis was demonstrated only in the mussel Mytilus trossulus. In addition to p53-related activity, a pro-inflammatory role for MDM2 in mammals has recently been described. In the present paper, we report the Real-time RT-PCR expression analysis of the mdm homolog gene in digestive gland tissue of Mytilus galloprovincialis collected from four different sites in the Campania region (Italy) during a single year. Our results revealed a positive correlation between the expression level of the mdm homolog and the percentage of chronic inflammatory lesions, both of which are increased during the summer period, suggesting a previously unidentified involvement of mdm in inflammatory processes in invertebrate species. Results obtained pointed out the potential interest of the use of mdm gene expression in marine food and seawater quality evaluation monitoring programs.
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884
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Hein N, Hannan KM, George AJ, Sanij E, Hannan RD. The nucleolus: an emerging target for cancer therapy. Trends Mol Med 2013; 19:643-54. [PMID: 23953479 DOI: 10.1016/j.molmed.2013.07.005] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/10/2013] [Accepted: 07/15/2013] [Indexed: 02/07/2023]
Abstract
For over 100 years, pathologists have utilised an increase in size and number of nucleoli, the subnuclear site of ribosome synthesis, as a marker of aggressive tumours. Despite this, the contribution of the nucleolus and ribosomal RNA synthesis to cancer has been largely overlooked. This concept has recently changed with the demonstration that the nucleolus indirectly controls numerous other cellular functions, in particular, the cellular activity of the critical tumour suppressor protein, p53. Moreover, selective inhibition of ribosomal gene transcription in the nucleolus has been shown to be an effective therapeutic strategy to promote cancer-specific activation of p53. This article reviews the largely untapped potential of the nucleolus and ribosomal gene transcription as exciting new targets for cancer therapy.
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Affiliation(s)
- Nadine Hein
- Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, 3002, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, 3010, Victoria, Australia
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885
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Gyurkó DM, Veres DV, Módos D, Lenti K, Korcsmáros T, Csermely P. Adaptation and learning of molecular networks as a description of cancer development at the systems-level: Potential use in anti-cancer therapies. Semin Cancer Biol 2013; 23:262-9. [DOI: 10.1016/j.semcancer.2013.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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886
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Tanabe S. Perspectives of gene combinations in phenotype presentation. World J Stem Cells 2013; 5:61-67. [PMID: 23951387 PMCID: PMC3744131 DOI: 10.4252/wjsc.v5.i3.61] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 04/24/2013] [Accepted: 06/10/2013] [Indexed: 02/06/2023] Open
Abstract
Cells exhibit a variety of phenotypes in different stages and diseases. Although several markers for cellular phenotypes have been identified, gene combinations denoting cellular phenotypes have not been completely elucidated. Recent advances in gene analysis have revealed that various gene expression patterns are observed in each cell species and status. In this review, the perspectives of gene combinations in cellular phenotype presentation are discussed. Gene expression profiles change during cellular processes, such as cell proliferation, cell differentiation, and cell death. In addition, epigenetic regulation increases the complexity of the gene expression profile. The role of gene combinations and panels of gene combinations in each cellular condition are also discussed.
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887
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Panduratin A, a possible inhibitor in metastasized A549 cells through inhibition of NF-kappa B translocation and chemoinvasion. Molecules 2013; 18:8764-78. [PMID: 23887718 PMCID: PMC6270481 DOI: 10.3390/molecules18088764] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/21/2013] [Accepted: 06/28/2013] [Indexed: 01/01/2023] Open
Abstract
In the present study, we investigated the effects of panduratin A (PA), isolated from Boesenbergia rotunda, on apoptosis and chemoinvasion in A549 human non-small cell lung cancer cells. Activation of the executioner procaspase-3 by PA was found to be dose-dependent. Caspase-3 activity was significantly elevated at the 5 µg/mL level of PA treatment and progressed to a maximal level. However, no significant elevated level was detected on procaspase-8. These findings suggest that PA activated caspase-3 but not caspase-8. Numerous nuclei of PA treated A549 cells stained brightly by anti-cleaved PARP antibody through High Content Screening. This result further confirmed that PA induced apoptotic cell death was mediated through activation of caspase-3 and eventually led to PARP cleavage. Treatment of A549 cells with PA resulted in a strong inhibition of NF-κB activation, which was consistent with a decrease in nuclear levels of NF-κB/p65 and NF-κB/p50 and the elevation of p53 and p21. Besides that, we also showed that PA significantly inhibited the invasion of A549 cells in a dose-dependent manner through reducing the secretion of MMP-2 of A549 cells gelatin zymography assay. Our findings not only provide the effects of PA, but may also be important in the design of therapeutic protocols that involve targeting of either p53 or NF-κB.
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888
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Daftuar L, Zhu Y, Jacq X, Prives C. Ribosomal proteins RPL37, RPS15 and RPS20 regulate the Mdm2-p53-MdmX network. PLoS One 2013; 8:e68667. [PMID: 23874713 PMCID: PMC3713000 DOI: 10.1371/journal.pone.0068667] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/06/2013] [Indexed: 11/17/2022] Open
Abstract
Changes to the nucleolus, the site of ribosome production, have long been linked to cancer, and mutations in several ribosomal proteins (RPs) have been associated with an increased risk for cancer in human diseases. Relevantly, a number of RPs have been shown to bind to MDM2 and inhibit MDM2 E3 ligase activity, leading to p53 stabilization and cell cycle arrest, thus revealing a RP-Mdm2-p53 signaling pathway that is critical for ribosome biogenesis surveillance. Here, we have identified RPL37, RPS15, and RPS20 as RPs that can also bind Mdm2 and activate p53. We found that each of the aforementioned RPs, when ectopically expressed, can stabilize both co-expressed Flag-tagged Mdm2 and HA-tagged p53 in p53-null cells as well as endogenous p53 in a p53-containing cell line. For each RP, the mechanism of Mdm2 and p53 stabilization appears to be through inhibiting the E3 ubiquitin ligase activity of Mdm2. Interestingly, although they are each capable of inducing cell death and cell cycle arrest, these RPs differ in the p53 target genes that are regulated upon their respective introduction into cells. Furthermore, each RP can downregulate MdmX levels but in distinct ways. Thus, RPL37, RPS15 and RPS20 regulate the Mdm2-p53-MdmX network but employ different mechanisms to do so.
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Affiliation(s)
- Lilyn Daftuar
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
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889
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George EV, Pharm J, Houston C, Al-Quran S, Brian G, Dong H, Hai W, Reeves W, Yang LJ. Breast implant-associated ALK-negative anaplastic large cell lymphoma: a case report and discussion of possible pathogenesis. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2013; 6:1631-1642. [PMID: 23923082 PMCID: PMC3726980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/01/2013] [Indexed: 06/02/2023]
Abstract
Breast implant associated anaplastic large cell lymphoma (BIA-ALCL) is a recently recognized clinical entity, with only 39 well-documented cases reported worldwide, including 3 fatalities. Because of its rarity, the clinical and pathologic features of this malignancy have yet to be fully defined. Moreover, the pathogenesis of ALCL in association with textured silicone gel breast implants is poorly understood. Here we report a case of BIA-ALCL arising in a 67-year-old woman with a mastectomy due to breast cancer followed by implantation of textured silicone gel breast prosthesis. The patient presented with breast enlargement and tenderness 8 years following reconstructive surgery. MRI revealed a fluid collection surrounding the affected breast implant. Pathologic examination confirmed the presence of malignant ALCL T cells that were CD30+, CD8+, CD15+, HLA-DR+, CD25+ ALK- and p53. A diagnosis of indolent BIA-ALCL was made since tumor cells were not found outside of the capsule. Interestingly, an extensive mixed lymphocytic infiltrate and ectopic lymphoid tissue (lymphoid neogenesis) adjacent to the fibrous implant capsule were present. The patient was treated with capsulectomy and implantation of new breast prostheses. Six months later, the patient was found to have BIA-ALCL involvement of an axillary lymph node with cytogenetic evolution of the tumor. To our knowledge, this is the sixth reported case of aggressive BIA-ALCL. Unique features of this case include the association with lymphoid neogenesis and the in vivo cytogenetic progression of the tumor. This case provides insight into the potential role of chronic inflammation and genetic instability in the pathogenesis of BIA-ALCL.
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Affiliation(s)
- Eva V George
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - John Pharm
- Department of Pathology, John D Archbold Memorial HospitalThomasville, GA 31799, USA
| | - Courtney Houston
- Department of Surgery, John D Archbold Memorial HospitalThomasville, GA 31799, USA
| | - Semar Al-Quran
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - Grey Brian
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - Huijia Dong
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - Wang Hai
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - Westley Reeves
- Department of Medicine, University of Florida College of MedicineGainesville, FL 32607
| | - Li-Jun Yang
- Departments of Pathology, Immunology, Laboratory Medicine, University of Florida College of MedicineGainesville, FL 32607
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890
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Shen M, Schmitt S, Buac D, Dou QP. Targeting the ubiquitin-proteasome system for cancer therapy. Expert Opin Ther Targets 2013; 17:1091-108. [PMID: 23822887 DOI: 10.1517/14728222.2013.815728] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
INTRODUCTION The ubiquitin-proteasome system (UPS) degrades 80 - 90% of intracellular proteins. Cancer cells take advantage of the UPS for their increased growth and decreased apoptotic cell death. Thus, the components that make up the UPS represent a diverse group of potential anti-cancer targets. The success of the first-in-class proteasome inhibitor bortezomib not only proved that the proteasome is a feasible and valuable anti-cancer target, but also inspired researchers to extensively explore other potential targets of this pathway. AREAS COVERED This review provides a broad overview of the UPS and its role in supporting cancer development and progression, especially in aspects of p53 inactivation, p27 turnover and NF-κB activation. Also, efforts toward the development of small molecule inhibitors (SMIs) targeting different steps in this pathway for cancer treatment are reviewed and discussed. EXPERT OPINION Whereas some of the targets in the UPS, such as the 20S proteasome, Nedd8 activating enzyme and HDM2, have been well-established and validated, there remains a large pool of candidates waiting to be investigated. Development of SMIs targeting the UPS has been largely facilitated by state-of-the-art technologies such as high-throughput screening and computer-assisted drug design, both of which require a better understanding of the targets of interest.
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Affiliation(s)
- Min Shen
- Wayne State University, Barbara Ann Karmanos Cancer Institute, School of Medicine, Department of Pharmacology, Detroit, MI 48201, USA
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891
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Nag S, Qin J, Srivenugopal KS, Wang M, Zhang R. The MDM2-p53 pathway revisited. J Biomed Res 2013; 27:254-71. [PMID: 23885265 PMCID: PMC3721034 DOI: 10.7555/jbr.27.20130030] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/12/2013] [Indexed: 12/15/2022] Open
Abstract
The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer onset and progression, and is negatively regulated by interaction with the oncoprotein MDM2. In human cancers, the TP53 gene is frequently mutated or deleted, or the wild-type p53 function is inhibited by high levels of MDM2, leading to downregulation of tumor suppressive p53 pathways. Thus, the inhibition of MDM2-p53 interaction presents an appealing therapeutic strategy for the treatment of cancer. However, recent studies have revealed the MDM2-p53 interaction to be more complex involving multiple levels of regulation by numerous cellular proteins and epigenetic mechanisms, making it imperative to reexamine this intricate interplay from a holistic viewpoint. This review aims to highlight the multifaceted network of molecules regulating the MDM2-p53 axis to better understand the pathway and exploit it for anticancer therapy.
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Affiliation(s)
- Subhasree Nag
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
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892
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Abstract
Approximately 30% of patients with non-small cell lung cancer have the squamous cell carcinoma (SQCC) histological subtype. Although targeted therapies have improved outcomes in patients with adenocarcinoma, no agents are currently approved specifically for use in SQCC. The Cancer Genome Atlas (TCGA) recently published the results of comprehensive genomic analyses of tumor samples from 178 patients with SQCC of the lung. In this review, we briefly discuss key molecular aberrations reported by TCGA and other investigators and their potential therapeutic implications. Carefully designed preclinical and clinical studies based on these large-scale genomic analyses are critical to improve the outcomes of patients with SQCC of lung in the near future.
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Affiliation(s)
- Melissa Rooney
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63021, USA
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893
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Thériault BL, Dimaras H, Gallie BL, Corson TW. The genomic landscape of retinoblastoma: a review. Clin Exp Ophthalmol 2013; 42:33-52. [PMID: 24433356 DOI: 10.1111/ceo.12132] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 04/07/2013] [Indexed: 12/13/2022]
Abstract
Retinoblastoma is a paediatric ocular tumour that continues to reveal much about the genetic basis of cancer development. Study of genomic aberrations in retinoblastoma tumours has exposed important mechanisms of cancer development and identified oncogenes and tumour suppressors that offer potential points of therapeutic intervention. The recent development of next-generation genomic technologies has allowed further refinement of the genomic landscape of retinoblastoma at high resolution. In a relatively short period of time, a wealth of genetic and epigenetic data has emerged on a small number of tumour samples. These data highlight the inherent molecular complexity of this cancer despite the fact that most retinoblastomas are initiated by the inactivation of a single tumour suppressor gene. This review outlines the current understanding of the genomic, genetic and epigenetic changes in retinoblastoma, highlighting recent genome-wide analyses that have identified exciting candidate genes worthy of further validation as potential prognostic and therapeutic targets.
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Affiliation(s)
- Brigitte L Thériault
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
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894
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Noguchi T, Oishi S, Honda K, Kondoh Y, Saito T, Kubo T, Kaneda M, Ohno H, Osada H, Fujii N. Affinity-based screening of MDM2/MDMX-p53 interaction inhibitors by chemical array: identification of novel peptidic inhibitors. Bioorg Med Chem Lett 2013; 23:3802-5. [PMID: 23726030 DOI: 10.1016/j.bmcl.2013.04.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 10/26/2022]
Abstract
MDM2 and MDMX are oncoproteins that negatively regulate the activity and stability of the tumor suppressor protein p53. The inhibitors of protein-protein interactions (PPIs) of MDM2-p53 and MDMX-p53 represent potential anticancer agents. In this study, a novel approach for identifying MDM2-p53 and MDMX-p53 PPI inhibitor candidates by affinity-based screening using a chemical array has been established. A number of compounds from an in-house compound library, which were immobilized onto a chemical array, were screened for interaction with fluorescence-labeled MDM2 and MDMX proteins. The subsequent fluorescent polarization assay identified several compounds that inhibited MDM2-p53 and MDMX-p53 interactions.
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Affiliation(s)
- Taro Noguchi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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895
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Li C, Zhan C, Zhao L, Chen X, Lu WY, Lu W. Functional consequences of retro-inverso isomerization of a miniature protein inhibitor of the p53-MDM2 interaction. Bioorg Med Chem 2013; 21:4045-50. [PMID: 23660015 DOI: 10.1016/j.bmc.2013.04.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/08/2013] [Accepted: 04/10/2013] [Indexed: 12/13/2022]
Abstract
Peptide retro-inverso isomerization is thought to be functionally neutral and has been widely used as a tool for designing proteolytically stable d-isomers to recapitulate biological activities of their parent l-peptides. Despite success in a wide range of applications, exceptions amply exist that clearly defy this rule of thumb when parent l-peptides adopt an α-helical conformation in their bound state. The detrimental energetic effect of retro-inverso isomerization of an α-helical l-peptide on its target protein binding has been estimated to be 3.0-3.4kcal/mol. To better understand how the retro-inverso isomer of a structured protein works at the molecular level, we chemically synthesized and functionally characterized the retro-inverso isomer of a rationally designed miniature protein termed stingin of 18 amino acid residues, which adopts an N-terminal loop and a C-terminal α-helix stabilized by two intra-molecular disulfide bridges. Stingin emulated the transactivation peptide of the p53 tumor suppressor protein and bound with high affinity and via its C-terminal α-helix to MDM2 and MDMX-the two negative regulators of p53. We also prepared the retro isomer and d-enantiomer of stingin for comparative functional studies using fluorescence polarization and surface plasmon resonance techniques. We found that retro-inverso isomerization of l-stingin weakened its MDM2 binding by 720 fold (3.9kcal/mol); while enantiomerization of l-stingin drastically reduced its binding to MDM2 by three orders of magnitude, sequence reversal completely abolished it. Our findings demonstrate the limitation of peptide retro-inverso isomerization in molecular mimicry and reinforce the notion that the strategy works poorly with biologically active α-helical peptides due to inherent differences at the secondary and tertiary structural levels between an l-peptide and its retro-inverso isomer despite their similar side chain topologies at the primary structural level.(1.)
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Affiliation(s)
- Chong Li
- College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
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896
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PTEN plasticity: how the taming of a lethal gene can go too far. Trends Cell Biol 2013; 23:374-9. [PMID: 23578748 DOI: 10.1016/j.tcb.2013.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/08/2013] [Accepted: 03/12/2013] [Indexed: 12/20/2022]
Abstract
PTEN loss drives many cancers and recent genetic studies reveal that often PTEN is antagonised at the protein level without alteration of DNA or RNA expression. This scenario can already cause malignancy, because PTEN is haploinsufficient. We here review normally occurring mechanisms of PTEN protein regulation and discuss three processes where PTEN plasticity is needed: ischaemia, development, and wound healing. These situations demand transient PTEN suppression, whereas cancer exploits them for continuous proliferation and survival advantages. Therefore, increased understanding of PTEN plasticity may help us better interpret tumour development and ultimately lead to drug targets for PTEN supporting cancer therapy.
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897
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Xu R, Sen N, Paul BD, Snowman AM, Rao F, Vandiver MS, Xu J, Snyder SH. Inositol polyphosphate multikinase is a coactivator of p53-mediated transcription and cell death. Sci Signal 2013; 6:ra22. [PMID: 23550211 DOI: 10.1126/scisignal.2003405] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The tumor suppressor protein p53 is a critical stress response transcription factor that induces the expression of genes leading to cell cycle arrest, apoptosis, and tumor suppression. We found that mammalian inositol polyphosphate multikinase (IPMK) stimulated p53-mediated transcription by binding to p53 and enhancing its acetylation by the acetyltransferase p300 independently of its inositol phosphate and lipid kinase activities. Genetic or RNA interference (RNAi)-mediated knockdown of IPMK resulted in decreased activation of p53, decreased recruitment of p53 and p300 to target gene promoters, abrogated transcription of p53 target genes, and enhanced cell viability. Additionally, blocking the IPMK-p53 interaction decreased the extent of p53-mediated transcription. These results suggest that IPMK acts as a transcriptional coactivator for p53 and that it is an integral part of the p53 transcriptional complex facilitating cell death.
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Affiliation(s)
- Risheng Xu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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