1
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Li M, Li J, Lu X, Schroder R, Chandramohan A, Wuelfing WP, Templeton AC, Xu W, Gindy M, Kesisoglou F, Ling J, Sawyer T, Verma CS, Partridge AW, Su Y. Molecular Mechanism of P53 Peptide Permeation through Lipid Membranes from Solid-State NMR Spectroscopy and Molecular Dynamics Simulations. J Am Chem Soc 2024; 146:23075-23091. [PMID: 39110018 DOI: 10.1021/jacs.4c04230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Macrocyclic peptides show promise in targeting high-value therapeutically relevant binding sites due to their high affinity and specificity. However, their clinical application is often hindered by low membrane permeability, which limits their effectiveness against intracellular targets. Previous studies focused on peptide conformations in various solvents, leaving a gap in understanding their interactions with and translocation through lipid bilayers. Addressing this, our study explores the membrane interactions of stapled peptides, a subclass of macrocyclic peptides, using solid-state nuclear magnetic resonance (ssNMR) spectroscopy and molecular dynamics (MD) simulations. We conducted ssNMR measurements on ATSP-7041M, a prototypical stapled peptide, to understand its interaction with lipid membranes, leading to an MD-informed model for peptide membrane permeation. Our findings reveal that ATSP-7041M adopts a stable α-helical structure upon membrane binding, facilitated by a cation-π interaction between its phenylalanine side chain and the lipid headgroup. This interaction makes the membrane-bound state energetically favorable, facilitating membrane affinity and insertion. The bound peptide displayed asymmetric insertion depths, with the C-terminus penetrating deeper (approximately 9 Å) than the N-terminus (approximately 4.3 Å) relative to the lipid headgroups. Contrary to expectations, peptide dynamics was not hindered by membrane binding and exhibited rapid motions similar to cell-penetrating peptides. These dynamic interactions and peptide-lipid affinity appear to be crucial for membrane permeation. MD simulations indicated a thermodynamically stable transmembrane conformation of ATSP-7041M, reducing the energy barrier for translocation. Our study offers an in silico view of ATSP-7041M's translocation from the extracellular to the intracellular region, highlighting the significance of peptide-lipid interactions and dynamics in enabling peptide transit through membranes.
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Affiliation(s)
- Mingyue Li
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Jianguo Li
- Bioinformatics Institute at A*STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
- Singapore Eye Research Institute, 20 College Road Discovery Tower, Singapore 169856, Singapore
| | - Xingyu Lu
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
- Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Ryan Schroder
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | | | - W Peter Wuelfing
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Allen C Templeton
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Wei Xu
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Marian Gindy
- Small Molecule Science and Technology, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Filippos Kesisoglou
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Jing Ling
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Tomi Sawyer
- Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Chandra S Verma
- Bioinformatics Institute at A*STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
- School of Biological Sciences, Nanyang Technological University, 50 Nanyang Drive, Singapore 637551, Singapore
| | | | - Yongchao Su
- Pharmaceutical Sciences and Clinical Supply, Merck & Co., Inc., Rahway, New Jersey 07065, United States
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2
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Lu Y, Wu M, Xu Y, Yu L. The Development of p53-Targeted Therapies for Human Cancers. Cancers (Basel) 2023; 15:3560. [PMID: 37509223 PMCID: PMC10377496 DOI: 10.3390/cancers15143560] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
p53 plays a critical role in tumor suppression and is the most frequently mutated gene in human cancers. Most p53 mutants (mutp53) are missense mutations and are thus expressed in human cancers. In human cancers that retain wtp53, the wtp53 activities are downregulated through multiple mechanisms. For example, the overexpression of the negative regulators of p53, MDM2/MDMX, can also efficiently destabilize and inactivate wtp53. Therefore, both wtp53 and mutp53 have become promising and intensively explored therapeutic targets for cancer treatment. Current efforts include the development of small molecule compounds to disrupt the interaction between wtp53 and MDM2/MDMX in human cancers expressing wtp53 and to restore wtp53-like activity to p53 mutants in human cancers expressing mutp53. In addition, a synthetic lethality approach has been applied to identify signaling pathways affected by p53 dysfunction, which, when targeted, can lead to cell death. While an intensive search for p53-targeted cancer therapy has produced potential candidates with encouraging preclinical efficacy data, it remains challenging to develop such drugs with good efficacy and safety profiles. A more in-depth understanding of the mechanisms of action of these p53-targeting drugs will help to overcome these challenges.
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Affiliation(s)
- Yier Lu
- Department of Medical Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Meng Wu
- Department of Medical Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Yang Xu
- Department of Cardiology, The Second Affiliated Hospital, Cardiovascular Key Lab of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou 310009, China
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Lili Yu
- Department of Medical Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
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3
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Chinnam M, Xu C, Lama R, Zhang X, Cedeno CD, Wang Y, Stablewski AB, Goodrich DW, Wang X. MDM2 E3 ligase activity is essential for p53 regulation and cell cycle integrity. PLoS Genet 2022; 18:e1010171. [PMID: 35588102 PMCID: PMC9119546 DOI: 10.1371/journal.pgen.1010171] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/27/2022] [Indexed: 12/12/2022] Open
Abstract
MDM2 and MDM4 are key regulators of p53 and function as oncogenes when aberrantly expressed. MDM2 and MDM4 partner to suppress p53 transcriptional transactivation and polyubiquitinate p53 for degradation. The importance of MDM2 E3-ligase-mediated p53 regulation remains controversial. To resolve this, we generated mice with an Mdm2 L466A mutation that specifically compromises E2 interaction, abolishing MDM2 E3 ligase activity while preserving its ability to bind MDM4 and suppress p53 transactivation. Mdm2L466A/L466A mice exhibit p53-dependent embryonic lethality, demonstrating MDM2 E3 ligase activity is essential for p53 regulation in vivo. Unexpectedly, cells expressing Mdm2L466A manifest cell cycle G2-M transition defects and increased aneuploidy even in the absence of p53, suggesting MDM2 E3 ligase plays a p53-independent role in cell cycle regulation and genome integrity. Furthermore, cells bearing the E3-dead MDM2 mutant show aberrant cell cycle regulation in response to DNA damage. This study uncovers an uncharacterized role for MDM2’s E3 ligase activity in cell cycle beyond its essential role in regulating p53’s stability in vivo. The most frequently mutated protein in human cancer, the p53 tumor suppressor protein, is negatively regulated by the potentially oncogenic proteins MDM2 and MDM4. MDM2/MDM4 regulates p53 through two mechanisms, MDM2 E3 ubiquitin ligase activity marks p53 for degradation while MDM2/MDM4 can bind p53 to inhibit its ability to promote RNA transcription. Whether these mechanisms contribute to normal p53 regulation in vivo remains controversial. Using a newly developed mouse model that genetically separates these two mechanisms, we find that mice expressing MDM2 deficient specifically for E3 ubiquitin ligase activity do not survive embryonic development because unregulated p53 is lethal. In contrast to prior reports, MDM2 E3 ubiquitin ligase activity is thus required for p53 regulation during embryonic development. In addition, cells lacking MDM2 E3 ubiquitin ligase activity have cell cycle defects regardless of p53 status, uncovering a p53-independent function for MDM2 in regulating the cell cycle. Activating p53 by blocking physical interaction with MDM2/MDM4 is one currently pursued approach for cancer therapy, but this approach does not account for cancer-promoting activities of MDM2/MDM4 independent of p53. Findings reported here suggest targeting MDM2 E3 ligase activity directly may be advantageous as it would inhibit both p53-dependent and p53-independent oncogenic mechanisms.
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Affiliation(s)
- Meenalakshmi Chinnam
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
| | - Chao Xu
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
| | - Rati Lama
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
| | - Xiaojing Zhang
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
| | - Carlos D. Cedeno
- Flow and Image Cytometry Shared Resource, Buffalo, New York, United States of America
| | - Yanqing Wang
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
| | - Aimee B. Stablewski
- Department of Molecular & Cellular Biology, Buffalo, New York, United States of America
- Gene Targeting and Transgenic Shared Resource, Roswell Park Comprehensive Cancer Center, Buffalo, New York, United States of America
| | - David W. Goodrich
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
- * E-mail: (XW); (DWG)
| | - Xinjiang Wang
- Department of Pharmacology and Therapeutics, Buffalo, New York, United States of America
- * E-mail: (XW); (DWG)
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4
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Bartnykaitė A, Savukaitytė A, Ugenskienė R, Daukšaitė M, Korobeinikova E, Gudaitienė J, Juozaitytė E. Associations of MDM2 and MDM4 Polymorphisms with Early-Stage Breast Cancer. J Clin Med 2021; 10:jcm10040866. [PMID: 33669778 PMCID: PMC7922970 DOI: 10.3390/jcm10040866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/07/2021] [Accepted: 02/13/2021] [Indexed: 01/09/2023] Open
Abstract
Breast cancer is one of the most common cancers worldwide. Single nucleotide polymorphisms (SNPs) in MDM2 and MDM4 have been associated with various cancers. However, the influence on clinical characteristics of breast cancer has not been sufficiently investigated yet. Thus, this study aimed to investigate the relationship between SNPs in MDM2 (rs2279744, rs937283, rs937282) and MDM4 (rs1380576, rs4245739) and I-II stage breast cancer. For analysis, the genomic DNA was extracted from 100 unrelated women peripheral blood. Polymorphisms were analyzed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The study showed that MDM2 rs937283 and rs937282 were significantly associated with estrogen receptor status and human epidermal growth factor receptor 2 (HER2) status. SNPs rs1380576 and rs4245739, located in MDM4, were significantly associated with status of estrogen and progesterone receptors. Our findings suggest that rs937283 AG, rs937282 CG, rs1380576 CC, and rs4245739 AA genotypes were linked to hormonal receptor positive breast cancer and may be useful genetic markers for disease assessment.
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Affiliation(s)
- Agnė Bartnykaitė
- Oncology Research Laboratory, Oncology Institute, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania; (A.S.); (R.U.); (M.D.)
- Correspondence: ; Tel.: +3-703-778-7317
| | - Aistė Savukaitytė
- Oncology Research Laboratory, Oncology Institute, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania; (A.S.); (R.U.); (M.D.)
| | - Rasa Ugenskienė
- Oncology Research Laboratory, Oncology Institute, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania; (A.S.); (R.U.); (M.D.)
- Department of Genetics and Molecular Medicine, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, LT-50161 Kaunas, Lithuania
| | - Monika Daukšaitė
- Oncology Research Laboratory, Oncology Institute, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania; (A.S.); (R.U.); (M.D.)
| | - Erika Korobeinikova
- Department of Oncology and Hematology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, LT-50161 Kaunas, Lithuania; (E.K.); (J.G.); (E.J.)
| | - Jurgita Gudaitienė
- Department of Oncology and Hematology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, LT-50161 Kaunas, Lithuania; (E.K.); (J.G.); (E.J.)
| | - Elona Juozaitytė
- Department of Oncology and Hematology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, LT-50161 Kaunas, Lithuania; (E.K.); (J.G.); (E.J.)
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5
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Zhang X, Meng T, Cui S, Feng L, Liu D, Pang Q, Wang P. Ubiquitination of Nonhistone Proteins in Cancer Development and Treatment. Front Oncol 2021; 10:621294. [PMID: 33643919 PMCID: PMC7905169 DOI: 10.3389/fonc.2020.621294] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/24/2020] [Indexed: 12/14/2022] Open
Abstract
Ubiquitination, a crucial post-translation modification, regulates the localization and stability of the substrate proteins including nonhistone proteins. The ubiquitin-proteasome system (UPS) on nonhistone proteins plays a critical role in many cellular processes such as DNA repair, transcription, signal transduction, and apoptosis. Its dysregulation induces various diseases including cancer, and the identification of this process may provide potential therapeutic targets for cancer treatment. In this review, we summarize the regulatory roles of key UPS members on major nonhistone substrates in cancer-related processes, such as cell cycle, cell proliferation, apoptosis, DNA damage repair, inflammation, and T cell dysfunction in cancer. In addition, we also highlight novel therapeutic interventions targeting the UPS members (E1s, E2s, E3s, proteasomes, and deubiquitinating enzymes). Furthermore, we discuss the application of proteolysis-targeting chimeras (PROTACs) technology as a novel anticancer therapeutic strategy in modulating protein target levels with the aid of UPS.
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Affiliation(s)
- Xiuzhen Zhang
- School of Life Sciences, Shandong University of Technology, Zibo, China
| | - Tong Meng
- Tongji University Cancer Center, Shanghai Tenth People’s Hospital of Tongji University, School of Medicine, Tongji University, Shanghai, China
| | - Shuaishuai Cui
- School of Life Sciences, Shandong University of Technology, Zibo, China
| | - Ling Feng
- School of Life Sciences, Shandong University of Technology, Zibo, China
| | - Dongwu Liu
- School of Life Sciences, Shandong University of Technology, Zibo, China
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, China
| | - Qiuxiang Pang
- School of Life Sciences, Shandong University of Technology, Zibo, China
| | - Ping Wang
- School of Life Sciences, Shandong University of Technology, Zibo, China
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6
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Binding Ensembles of p53-MDM2 Peptide Inhibitors by Combining Bayesian Inference and Atomistic Simulations. Molecules 2021; 26:molecules26010198. [PMID: 33401765 PMCID: PMC7795311 DOI: 10.3390/molecules26010198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/26/2020] [Accepted: 12/28/2020] [Indexed: 01/21/2023] Open
Abstract
Designing peptide inhibitors of the p53-MDM2 interaction against cancer is of wide interest. Computational modeling and virtual screening are a well established step in the rational design of small molecules. But they face challenges for binding flexible peptide molecules that fold upon binding. We look at the ability of five different peptides, three of which are intrinsically disordered, to bind to MDM2 with a new Bayesian inference approach (MELD × MD). The method is able to capture the folding upon binding mechanism and differentiate binding preferences between the five peptides. Processing the ensembles with statistical mechanics tools depicts the most likely bound conformations and hints at differences in the binding mechanism. Finally, the study shows the importance of capturing two driving forces to binding in this system: the ability of peptides to adopt bound conformations (ΔGconformation) and the interaction between interface residues (ΔGinteraction).
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7
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Sanz G, Singh M, Peuget S, Selivanova G. Inhibition of p53 inhibitors: progress, challenges and perspectives. J Mol Cell Biol 2019; 11:586-599. [PMID: 31310659 PMCID: PMC6735775 DOI: 10.1093/jmcb/mjz075] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 12/20/2022] Open
Abstract
p53 is the major tumor suppressor and the most frequently inactivated gene in cancer. p53 could be disabled either by mutations or by upstream negative regulators, including, but not limited to MDM2 and MDMX. p53 activity is required for the prevention as well as for the eradication of cancers. Restoration of p53 activity in mouse models leads to the suppression of established tumors of different origin. These findings provide a strong support to the anti-cancer strategy aimed for p53 reactivation. In this review, we summarize recent progress in the development of small molecules, which restore the tumor suppressor function of wild-type p53 and discuss their clinical advance. We discuss different aspects of p53-mediated response, which contribute to suppression of tumors, including non-canonical p53 activities, such as regulation of immune response. While targeting p53 inhibitors is a very promising approach, there are certain limitations and concerns that the intensive research and clinical evaluation of compounds will hopefully help to overcome.
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Affiliation(s)
- Gema Sanz
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Madhurendra Singh
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Sylvain Peuget
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Galina Selivanova
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
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8
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Wang D, Ma L, Wang B, Liu J, Wei W. E3 ubiquitin ligases in cancer and implications for therapies. Cancer Metastasis Rev 2017; 36:683-702. [DOI: 10.1007/s10555-017-9703-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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9
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Li X, Liu C, Chen S, Hu H, Su J, Zou Y. d-Amino acid mutation of PMI as potent dual peptide inhibitors of p53-MDM2/MDMX interactions. Bioorg Med Chem Lett 2017; 27:4678-4681. [PMID: 28916339 DOI: 10.1016/j.bmcl.2017.09.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 09/04/2017] [Accepted: 09/05/2017] [Indexed: 12/26/2022]
Abstract
According to the previously reported potent dual l-peptide PMI of p53-MDM2/MDMX interactions, a series of d-amino acid mutational PMI analogues, PMI-1-4, with enhanced proteolytic resistence and in vitro tumor cell inhibitory activities were reported, of which Liposome-PMI-1 showed a stronger inhibitory activity against the U87 cell lines than Nutlin-3. This d-amino acid mutation strategy may give a hand for enhancing the potential of peptide drugs.
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Affiliation(s)
- Xiang Li
- Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai 200433, People's Republic of China; Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, United States
| | - Chao Liu
- Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Si Chen
- Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Honggang Hu
- Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Jiacan Su
- Changhai Hospital, Second Military Medical University, Shanghai 200433, People's Republic of China.
| | - Yan Zou
- Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai 200433, People's Republic of China.
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10
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Leroy B, Ballinger ML, Baran-Marszak F, Bond GL, Braithwaite A, Concin N, Donehower LA, El-Deiry WS, Fenaux P, Gaidano G, Langerød A, Hellstrom-Lindberg E, Iggo R, Lehmann-Che J, Mai PL, Malkin D, Moll UM, Myers JN, Nichols KE, Pospisilova S, Ashton-Prolla P, Rossi D, Savage SA, Strong LC, Tonin PN, Zeillinger R, Zenz T, Fraumeni JF, Taschner PEM, Hainaut P, Soussi T. Recommended Guidelines for Validation, Quality Control, and Reporting of TP53 Variants in Clinical Practice. Cancer Res 2017; 77:1250-1260. [PMID: 28254861 DOI: 10.1158/0008-5472.can-16-2179] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/12/2016] [Accepted: 11/16/2016] [Indexed: 12/21/2022]
Abstract
Accurate assessment of TP53 gene status in sporadic tumors and in the germline of individuals at high risk of cancer due to Li-Fraumeni Syndrome (LFS) has important clinical implications for diagnosis, surveillance, and therapy. Genomic data from more than 20,000 cancer genomes provide a wealth of information on cancer gene alterations and have confirmed TP53 as the most commonly mutated gene in human cancer. Analysis of a database of 70,000 TP53 variants reveals that the two newly discovered exons of the gene, exons 9β and 9γ, generated by alternative splicing, are the targets of inactivating mutation events in breast, liver, and head and neck tumors. Furthermore, germline rearrange-ments in intron 1 of TP53 are associated with LFS and are frequently observed in sporadic osteosarcoma. In this context of constantly growing genomic data, we discuss how screening strategies must be improved when assessing TP53 status in clinical samples. Finally, we discuss how TP53 alterations should be described by using accurate nomenclature to avoid confusion in scientific and clinical reports. Cancer Res; 77(6); 1250-60. ©2017 AACR.
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Affiliation(s)
- Bernard Leroy
- Sorbonne Université, UPMC Univ Paris 06, Paris, France
| | - Mandy L Ballinger
- Cancer Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Fanny Baran-Marszak
- Hôpital Avicenne, Assistance Publique-Hôpitaux De Paris, Bobigny, Service D'H ematologie Biologique, France
| | - Gareth L Bond
- Ludwig Institute for Cancer Research, University of Oxford, Nuffield Department of Clinical Medicine, Old Road Campus Research Building, Oxford, United Kingdom
| | - Antony Braithwaite
- Dept of Pathology, School of Medicine, University of Otago, Dunedin, New Zealand.,Children's Medical Research Institute, University of Sydney, Westmead NSW, Australia
| | - Nicole Concin
- Department of Gynecology and Obstetrics, Innsbruck Medical University, Innsbruck, Austria
| | | | - Wafik S El-Deiry
- Department of Hematology/Oncology and Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Pierre Fenaux
- Service d'hématologie séniors, Hôpital St Louis/Université Paris 7, 1 avenue Claude Vellefaux, Paris, France
| | - Gianluca Gaidano
- Division of Hematology, Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Anita Langerød
- Department of Genetics, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Eva Hellstrom-Lindberg
- Karolinska Institute, Department of Medicine, Center for Hematology and Regenerative Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Richard Iggo
- Bergonié Cancer Institute University of Bordeaux 229 cours de l'Argonne 33076 Bordeaux, France
| | | | - Phuong L Mai
- Cancer Genetics Program, Magee Womens Hospital, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - David Malkin
- Division of Hematology/Oncology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Ute M Moll
- Department of Pathology, Stony Brook University, Stony Brook, New York
| | - Jeffrey N Myers
- The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Kim E Nichols
- Department of Oncology, Division of Cancer Predisposition, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Sarka Pospisilova
- Masaryk University, CEITEC - Molecular Medicine and University Hospital Brno, Department of Internal Medicine - Hematology and Oncology, Brno, Czech Republic
| | - Patricia Ashton-Prolla
- Universidade Federal do Rio Grande do Sul (UFRGS) e Serviço deGenética Médica-HCPA, Rua Ramiro Barcelos, Porto Alegre, Brasil
| | - Davide Rossi
- Division of Hematology, Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy
| | - Sharon A Savage
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland
| | - Louise C Strong
- The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Patricia N Tonin
- Departments of Medicine and Human Genetics, McGill University and Cancer Research Program, The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Robert Zeillinger
- Molecular Oncology Group, Department of Obstetrics and Gynaecology, Medical University of Vienna, Vienna, Austria
| | - Thorsten Zenz
- University of Heidelberg, Department of Medicine V, Heidelberg, Germany; Department of Translational Oncology, National Center for Tumor Diseases and German Cancer Research Center (dkfz), Heidelberg, Germany
| | - Joseph F Fraumeni
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland
| | - Peter E M Taschner
- Generade Centre of Expertise Genomics and University of Applied Sciences Leiden, Leiden, the Netherlands
| | - Pierre Hainaut
- Institut Albert Bonniot, Inserm 823, Université Grenoble Alpes, Rond Point de la Chantourne, La Tronche, France
| | - Thierry Soussi
- Sorbonne Université, UPMC Univ Paris 06, Paris, France. .,Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Stockholm, Sweden.,INSERM, U1138, Centre de Recherche des Cordeliers, Paris, France
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11
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Tracz-Gaszewska Z, Klimczak M, Biecek P, Herok M, Kosinski M, Olszewski MB, Czerwińska P, Wiech M, Wiznerowicz M, Zylicz A, Zylicz M, Wawrzynow B. Molecular chaperones in the acquisition of cancer cell chemoresistance with mutated TP53 and MDM2 up-regulation. Oncotarget 2017; 8:82123-82143. [PMID: 29137250 PMCID: PMC5669876 DOI: 10.18632/oncotarget.18899] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 06/13/2017] [Indexed: 01/17/2023] Open
Abstract
Utilizing the TCGA PANCAN12 dataset we discovered that cancer patients with mutations in TP53 tumor suppressor and overexpression of MDM2 oncogene exhibited decreased survival post treatment. Interestingly, in the case of breast cancer patients, this phenomenon correlated with high expression level of several molecular chaperones belonging to the HSPA, DNAJB and HSPC families. To verify the hypothesis that such a genetic background may promote chaperone-mediated chemoresistance, we employed breast and lung cancer cell lines that constitutively overexpressed heat shock proteins and have shown that HSPA1A/HSP70 and DNAJB1/HSP40 facilitated the binding of mutated p53 to the TAp73α protein. This chaperone-mediated mutated p53–TAp73α complex induced chemoresistance to DNA damaging reagents, like Cisplatin, Doxorubicin, Etoposide or Camptothecin. Importantly, when the MDM2 oncogene was overexpressed, heat shock proteins were displaced and a stable multiprotein complex comprising of mutated p53-TAp73α-MDM2 was formed, additionally amplifying cancer cells chemoresistance. Our findings demonstrate that molecular chaperones aid cancer cells in surviving the cytotoxic effect of chemotherapeutics and may have therapeutic implications.
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Affiliation(s)
- Zuzanna Tracz-Gaszewska
- International Institute of Molecular and Cell Biology, Warsaw, Poland.,Institute of Biochemistry and Biophysics, PAS, Warsaw, Poland
| | - Marta Klimczak
- International Institute of Molecular and Cell Biology, Warsaw, Poland.,Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Przemyslaw Biecek
- Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw, Warsaw, Poland.,Faculty of Mathematics and Information Science, Warsaw University of Technology, Warsaw, Poland
| | - Marcin Herok
- International Institute of Molecular and Cell Biology, Warsaw, Poland.,Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
| | - Marcin Kosinski
- Faculty of Mathematics and Information Science, Warsaw University of Technology, Warsaw, Poland.,Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw, Warsaw, Poland
| | | | - Patrycja Czerwińska
- International Institute of Molecular and Cell Biology, Warsaw, Poland.,Laboratory of Gene Therapy, Department of Cancer Immunology, The Greater Poland Cancer Center, Poznan, Poland
| | - Milena Wiech
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Maciej Wiznerowicz
- Laboratory of Gene Therapy, Department of Cancer Immunology, The Greater Poland Cancer Center, Poznan, Poland
| | - Alicja Zylicz
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Maciej Zylicz
- International Institute of Molecular and Cell Biology, Warsaw, Poland
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12
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Hao L, Leng J, Xiao R, Kingsley T, Li X, Tu Z, Yang X, Deng X, Xiong M, Xiong J, Zhang Q. Bioinformatics analysis of the prognostic value of Tripartite Motif 28 in breast cancer. Oncol Lett 2017; 13:2670-2678. [PMID: 28454449 PMCID: PMC5403292 DOI: 10.3892/ol.2017.5764] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 12/06/2016] [Indexed: 02/06/2023] Open
Abstract
Tripartite motif containing 28 (TRIM28) is a transcriptional regulator acting as an essential corepressor for Krüppel-associated box zinc finger domain-containing proteins in multiple tissue and cell types. An increasing number of studies have investigated the function of TRIM28; however, its prognostic value in breast cancer (BC) remains unclear. In the present study, the expression of TRIM28 was identified to be significantly higher in cancerous compared with healthy tissue samples. Furthermore, it was demonstrated that TRIM28 expression was significantly correlated with several clinicopathological characteristics of patients with BC, such as p53 mutation, tumor recurrence and Elston grade of the tumor. In addition, a protein-protein interaction network was created to illustrate the interactions of TRIM28 with other proteins. The prognostic value of TRIM28 in patients with BC was investigated using the Kaplan-Meier Plotter database, which revealed that high expression of TRIM28 is a predictor of poor prognosis in patients with BC. In conclusion, the results of the present study indicate that TRIM28 provides a survival advantage to patients with BC and is a novel prognostic biomarker, in addition to being a therapeutic target for the treatment of BC.
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Affiliation(s)
- Ling Hao
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Jun Leng
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Ruijing Xiao
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Tembo Kingsley
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xinran Li
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Zhenbo Tu
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xiangyong Yang
- College of Engineering Technology, Hubei University of Technology, Wuhan, Hubei 430068, P.R. China
| | - Xinzhou Deng
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Meng Xiong
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Jie Xiong
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Qiuping Zhang
- Department of Immunology, School of Basic Medical Science, Wuhan University, Wuhan, Hubei 430071, P.R. China
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13
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Hernández-Monge J, Rousset-Roman AB, Medina-Medina I, Olivares-Illana V. Dual function of MDM2 and MDMX toward the tumor suppressors p53 and RB. Genes Cancer 2016; 7:278-287. [PMID: 28050229 PMCID: PMC5115168 DOI: 10.18632/genesandcancer.120] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The orchestrated crosstalk between the retinoblastoma (RB) and p53 pathways contributes to preserving proper homeostasis within the cell. The deregulation of one or both pathways is a common factor in the development of most types of human cancer. The proto-oncoproteins MDMX and MDM2 are the main regulators of the well- known tumor suppressor p53 protein. Under normal conditions, MDM2 and MDMX inhibit p53, either via repression of its transcriptional activity by protein-protein interaction, or via polyubiquitination as a result of MDM2-E3 ubiquitin ligase activity, for which MDM2 needs to dimerize with MDMX. Under genotoxic stress conditions, both become positive regulators of p53. The ATM-dependent phosphorylation of MDM2 and MDMX allow them to bind p53 mRNA, these interactions promote p53 translation. MDM2 and MDMX are also being revealed as effective regulators of the RB protein. MDM2 is able to degrade RB by two different mechanisms, that is, by ubiquitin dependent and independent pathways. MDMX enhances the ability of MDM2 to bind and degrade RB protein. However, MDMX also seems to stabilize RB through interaction and competition with MDM2. Here, we will contextualize the findings that suggest that the MDM2 and MDMX proteins have a dual function on both p53 and RB.
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Affiliation(s)
- Jesús Hernández-Monge
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Adriana Berenice Rousset-Roman
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Ixaura Medina-Medina
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
| | - Vanesa Olivares-Illana
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Av Manuel Nava No 6 Zona Universitaria CP 78290. SLP, México
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14
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Dewaele M, Tabaglio T, Willekens K, Bezzi M, Teo SX, Low DHP, Koh CM, Rambow F, Fiers M, Rogiers A, Radaelli E, Al-Haddawi M, Tan SY, Hermans E, Amant F, Yan H, Lakshmanan M, Koumar RC, Lim ST, Derheimer FA, Campbell RM, Bonday Z, Tergaonkar V, Shackleton M, Blattner C, Marine JC, Guccione E. Antisense oligonucleotide-mediated MDM4 exon 6 skipping impairs tumor growth. J Clin Invest 2015; 126:68-84. [PMID: 26595814 DOI: 10.1172/jci82534] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 10/09/2015] [Indexed: 12/27/2022] Open
Abstract
MDM4 is a promising target for cancer therapy, as it is undetectable in most normal adult tissues but often upregulated in cancer cells to dampen p53 tumor-suppressor function. The mechanisms that underlie MDM4 upregulation in cancer cells are largely unknown. Here, we have shown that this key oncogenic event mainly depends on a specific alternative splicing switch. We determined that while a nonsense-mediated, decay-targeted isoform of MDM4 (MDM4-S) is produced in normal adult tissues as a result of exon 6 skipping, enhanced exon 6 inclusion leads to expression of full-length MDM4 in a large number of human cancers. Although this alternative splicing event is likely regulated by multiple splicing factors, we identified the SRSF3 oncoprotein as a key enhancer of exon 6 inclusion. In multiple human melanoma cell lines and in melanoma patient-derived xenograft (PDX) mouse models, antisense oligonucleotide-mediated (ASO-mediated) skipping of exon 6 decreased MDM4 abundance, inhibited melanoma growth, and enhanced sensitivity to MAPK-targeting therapeutics. Additionally, ASO-based MDM4 targeting reduced diffuse large B cell lymphoma PDX growth. As full-length MDM4 is enhanced in multiple human tumors, our data indicate that this strategy is applicable to a wide range of tumor types. We conclude that enhanced MDM4 exon 6 inclusion is a common oncogenic event and has potential as a clinically compatible therapeutic target.
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15
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Micewicz ED, Sharma S, Waring AJ, Luong HT, McBride WH, Ruchala P. Bridged Analogues for p53-Dependent Cancer Therapy Obtained by S-Alkylation. Int J Pept Res Ther 2015; 22:67-81. [PMID: 26957954 DOI: 10.1007/s10989-015-9487-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A small library of anticancer, cell-permeating, stapled peptides based on potent dual-specific antagonist of p53-MDM2/MDMX interactions, PMI-N8A, was synthesized, characterized and screened for anticancer activity against human colorectal cancer cell line, HCT-116. Employed synthetic modifications included: S-alkylation-based stapling, point mutations increasing hydrophobicity in key residues as well as improvement of cell-permeability by introduction of polycationic sequence(s) that were woven into the sequence of parental peptide. Selected analogue, ArB14Co, was also tested in vivo and exhibited potent anticancer bioactivity at the low dose (3.0 mg/kg). Collectively, our findings suggest that application of stapling in combination with rational design of polycationic short analogues may be a suitable approach in the development of physiologically active p53-MDM2/MDMX peptide inhibitors.
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Affiliation(s)
- Ewa D Micewicz
- Department of Radiation Oncology, University of California at Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | - Shantanu Sharma
- Materials and Process Simulation Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alan J Waring
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA, Medical Center, 1000 West Carson Street, Torrance, CA 90502, USA
| | - Hai T Luong
- Department of Analytical Operations, Gilead Sciences, Inc., 4049 Avenida de la Plata, Oceanside CA, 92056, USA
| | - William H McBride
- Department of Radiation Oncology, University of California at Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | - Piotr Ruchala
- Department of Psychiatry and Biobehavioral Sciences, University of California at Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90024, USA
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16
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Haupt S, Buckley D, Pang JMB, Panimaya J, Paul PJ, Gamell C, Takano EA, Lee YY, Hiddingh S, Rogers TM, Teunisse AFAS, Herold MJ, Marine JC, Fox SB, Jochemsen A, Haupt Y. Targeting Mdmx to treat breast cancers with wild-type p53. Cell Death Dis 2015; 6:e1821. [PMID: 26181202 PMCID: PMC4650725 DOI: 10.1038/cddis.2015.173] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/15/2015] [Accepted: 05/22/2015] [Indexed: 01/07/2023]
Abstract
The function of the tumor suppressor p53 is universally compromised in cancers. It is the most frequently mutated gene in human cancers (reviewed). In cases where p53 is not mutated, alternative regulatory pathways inactivate its tumor suppressive functions. This is primarily achieved through elevation in the expression of the key inhibitors of p53: Mdm2 or Mdmx (also called Mdm4) (reviewed). In breast cancer (BrCa), the frequency of p53 mutations varies markedly between the different subtypes, with basal-like BrCas bearing a high frequency of p53 mutations, whereas luminal BrCas generally express wild-type (wt) p53. Here we show that Mdmx is unexpectedly highly expressed in normal breast epithelial cells and its expression is further elevated in most luminal BrCas, whereas p53 expression is generally low, consistent with wt p53 status. Inducible knockdown (KD) of Mdmx in luminal BrCa MCF-7 cells impedes the growth of these cells in culture, in a p53-dependent manner. Importantly, KD of Mdmx in orthotopic xenograft transplants resulted in growth inhibition associated with prolonged survival, both in a preventative model and also in a treatment model. Growth impediment in response to Mdmx KD was associated with cellular senescence. The growth inhibitory capacity of Mdmx KD was recapitulated in an additional luminal BrCa cell line MPE600, which expresses wt p53. Further, the growth inhibitory capacity of Mdmx KD was also demonstrated in the wt p53 basal-like cell line SKBR7 line. These results identify Mdmx growth dependency in wt p53 expressing BrCas, across a range of subtypes. Based on our findings, we propose that Mdmx targeting is an attractive strategy for treating BrCas harboring wt p53.
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Affiliation(s)
- S Haupt
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - D Buckley
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - J-M B Pang
- Department of Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - J Panimaya
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - P J Paul
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - C Gamell
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - E A Takano
- Department of Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Y Ying Lee
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - S Hiddingh
- Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - T-M Rogers
- Department of Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - A F A S Teunisse
- Department of Molecular Cell Biology, University Medical Centre, Leiden, The Netherlands
| | - M J Herold
- 1] Department of Molecular Genetics of Cancer, The Walter and Eliza Hall Institute, Parkville, Victoria, Australia [2] Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - J-C Marine
- Center for Human Genetics, KU Leuven, Leuven, Belgium
| | - S B Fox
- 1] Department of Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia [2] Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia
| | - A Jochemsen
- Department of Molecular Cell Biology, University Medical Centre, Leiden, The Netherlands
| | - Y Haupt
- 1] Tumor Suppression Laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia [2] Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia [3] Department of Pathology, University of Melbourne, Parkville, Victoria, Australia [4] Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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17
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Abstract
It has been confirmed through studies using the technique of unbiased sequencing that the TP53 tumour suppressor is the most frequently inactivated gene in cancer. This finding, together with results from earlier studies, provides compelling evidence for the idea that p53 ablation is required for the development and maintenance of tumours. Genetic reconstitution of the function of p53 leads to the suppression of established tumours as shown in mouse models. This strongly supports the notion that p53 reactivation by small molecules could provide an efficient strategy to treat cancer. In this review, we summarize recent advances in the development of small molecules that restore the function of mutant p53 by different mechanisms, including stabilization of its folding by Apr-246, which is currently being tested in a Phase II clinical trial. We discuss several classes of compounds that reactivate wild-type p53, such as Mdm2 inhibitors, which are currently undergoing clinical testing, MdmX inhibitors and molecules targeting factors upstream of Mdm2/X or p53 itself. Finally, we consider the clinical applications of compounds targeting p53 and the p53 pathway.
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Affiliation(s)
- J Zawacka-Pankau
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - G Selivanova
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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18
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Bielskienė K, Bagdonienė L, Mozūraitienė J, Kazbarienė B, Janulionis E. E3 ubiquitin ligases as drug targets and prognostic biomarkers in melanoma. MEDICINA-LITHUANIA 2015; 51:1-9. [PMID: 25744769 DOI: 10.1016/j.medici.2015.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 01/18/2015] [Indexed: 12/30/2022]
Abstract
Melanomas are highly proliferative and invasive, and are most frequently metastatic. Despite many advances in cancer treatment over the last several decades, the prognosis for patients with advanced melanoma remains poor. New treatment methods and strategies are necessary. The main hallmark of cancer is uncontrolled cellular proliferation with alterations in the expression of proteins. Ubiquitin and ubiquitin-related proteins posttranslationally modify proteins and thereby alter their functions. The ubiquitination process is involved in various physiological responses, including cell growth, cell death, and DNA damage repair. E3 ligases, the most specific enzymes of ubiquitination system, participate in the turnover of many key regulatory proteins and in the development of cancer. E3 ligases are of interest as drug targets for their ability to regulate proteins stability and functions. Compared to the general proteasome inhibitor bortezomib, which blocks the entire protein degradation, drugs that target a particular E3 ligase are expected to have better selectivity with less associated toxicity. Components of different E3 ligases complexes (FBW7, MDM2, RBX1/ROC1, RBX2/ROC2, cullins and many others) are known as oncogenes or tumor suppressors in melanomagenesis. These proteins participate in regulation of different cellular pathways and such important proteins in cancer development as p53 and Notch. In this review we summarized published data on the role of known E3 ligases in the development of melanoma and discuss the inhibitors of E3 ligases as a novel approach for the treatment of malignant melanomas.
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Affiliation(s)
| | - Lida Bagdonienė
- Department of Biochemistry and Molecular Biology, Vilnius University, Vilnius, Lithuania.
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19
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Bardot B, Bouarich-Bourimi R, Leemput J, Lejour V, Hamon A, Plancke L, Jochemsen AG, Simeonova I, Fang M, Toledo F. Mice engineered for an obligatory Mdm4 exon skipping express higher levels of the Mdm4-S isoform but exhibit increased p53 activity. Oncogene 2014; 34:2943-8. [PMID: 25088193 DOI: 10.1038/onc.2014.230] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/15/2014] [Accepted: 06/24/2014] [Indexed: 12/14/2022]
Abstract
Mdm4, a protein related to the ubiquitin-ligase Mdm2, is an essential inhibitor of tumor suppressor protein p53. In both human and mouse cells, the Mdm4 gene encodes two major transcripts: one encodes the full-length oncoprotein (designated below as Mdm4-FL), whereas the other, resulting from a variant splicing that skips exon 6, encodes the shorter isoform Mdm4-S. Importantly, increased Mdm4-S mRNA levels were observed in several human cancers, and correlated with poor survival. However, the role of Mdm4-S in cancer progression remains controversial, because the Mdm4-S protein appeared to be a potent p53 inhibitor when overexpressed, but the splice variant also leads to a decrease in Mdm4-FL expression. To unambiguously determine the physiological impact of the Mdm4-S splice variant, we generated a mouse model with a targeted deletion of the Mdm4 exon 6, thereby creating an obligatory exon skipping. The mutant allele (Mdm4(ΔE6)) prevented the expression of Mdm4-FL, but also led to increased Mdm4-S mRNA levels. Mice homozygous for this allele died during embryonic development, but were rescued by a concomitant p53 deficiency. Furthermore in a hypomorphic p53(ΔP/ΔP) context, the Mdm4(ΔE6) allele led to p53 activation and delayed the growth of oncogene-induced tumors. We next determined the effect of Mdm4(+/ΔE6) heterozygosity in a hypermorphic p53(+/Δ31) genetic background, recently shown to be extremely sensitive to Mdm4 activity. Mdm4(+/ΔE6) p53(+/Δ31) pups were born, but suffered from aplastic anemia and died before weaning, again indicating an increased p53 activity. Our results demonstrate that the main effect of a skipping of Mdm4 exon 6 is not the synthesis of the Mdm4-S protein, but rather a decrease in Mdm4-FL expression. These and other data suggest that increased Mdm4-S mRNA levels might correlate with more aggressive cancers without encoding significant amounts of a potential oncoprotein. Hypotheses that may account for this apparent paradox are discussed.
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Affiliation(s)
- B Bardot
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - R Bouarich-Bourimi
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - J Leemput
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - V Lejour
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - A Hamon
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - L Plancke
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - A G Jochemsen
- Leiden University Medical Center, Leiden, The Netherlands
| | - I Simeonova
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - M Fang
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
| | - F Toledo
- 1] Institut Curie, Centre de recherche, Genetics of Tumor Suppression (Equipe Labellisée Ligue 2014), Paris, France [2] UPMC Univ Paris 06, Paris, France [3] CNRS UMR 3244, Paris, France
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20
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The orally bioavailable MDM2 antagonist RG7112 and pegylated interferon α 2a target JAK2V617F-positive progenitor and stem cells. Blood 2014; 124:771-9. [PMID: 24869939 DOI: 10.1182/blood-2013-11-536854] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Philadelphia chromosomal-negative chronic myeloproliferative neoplasms (MPNs) originate at the level of the hematopoietic stem cell (HSC). The protracted clinical course of the MPNs has limited the use of potentially toxic treatment modalities, which may eliminate the responsible malignant clone. Treatment with low doses of RG7112, an orally available small-molecule inhibitor of p53-MDM2, both alone and combined with pegylated interferon α 2a (Peg-IFNα 2a), significantly decreased MPN colony-forming unit-granulocyte macrophage and burst-forming unit-erythroid numbers and preferentially eliminated the total number of JAKV617F(+) MPN hematopoietic progenitor cells. The effects of RG7112 and Peg-IFNα 2a on MPN progenitor cells were dependent on blocking p53-MDM2 interactions and activating the p53 pathway, thereby increasing MPN CD34(+) cell apoptosis. Treatment of polycythemia vera (PV) and primary myelofibrosis (PMF) CD34(+) cells with low doses of RG7112 and Peg-IFNα 2a before their transplantation into immune-deficient mice decreased the degree of donor-derived chimerism as well as the JAK2V617F allele burden, indicating that these drugs can each alone or in combination deplete MPN HSCs. These results provide a rationale for the use of combinations of low doses of RG7112 and Peg-IFNα 2a for the treatment of PV or PMF patients with the intent of altering their natural history.
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21
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Selivanova G. Wild type p53 reactivation: from lab bench to clinic. FEBS Lett 2014; 588:2628-38. [PMID: 24726725 DOI: 10.1016/j.febslet.2014.03.049] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 03/28/2014] [Accepted: 03/31/2014] [Indexed: 12/17/2022]
Abstract
The p53 tumor suppressor is the most frequently inactivated gene in cancer. Several mouse models have demonstrated that the reconstitution of the p53 function suppresses the growth of established tumors. These facts, taken together, promote the idea of p53 reactivation as a strategy to combat cancer. This review will focus on recent advances in the development of small molecules which restore the function of wild type p53 by blocking its inhibitors Mdm2 and MdmX or their upstream regulators and discuss the impact of different p53 functions for tumor prevention and tumor eradication. Finally, the recent progress in p53 research will be analyzed concerning the role of p53 cofactors and cellular environment in the biological response upon p53 reactivation and how this can be applied in clinic.
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Affiliation(s)
- Galina Selivanova
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsvag 16, SE-17177 Stockholm, Sweden.
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22
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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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Stapled α-helical peptide drug development: a potent dual inhibitor of MDM2 and MDMX for p53-dependent cancer therapy. Proc Natl Acad Sci U S A 2013; 110:E3445-54. [PMID: 23946421 DOI: 10.1073/pnas.1303002110] [Citation(s) in RCA: 491] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Stapled α-helical peptides have emerged as a promising new modality for a wide range of therapeutic targets. Here, we report a potent and selective dual inhibitor of MDM2 and MDMX, ATSP-7041, which effectively activates the p53 pathway in tumors in vitro and in vivo. Specifically, ATSP-7041 binds both MDM2 and MDMX with nanomolar affinities, shows submicromolar cellular activities in cancer cell lines in the presence of serum, and demonstrates highly specific, on-target mechanism of action. A high resolution (1.7-Å) X-ray crystal structure reveals its molecular interactions with the target protein MDMX, including multiple contacts with key amino acids as well as a role for the hydrocarbon staple itself in target engagement. Most importantly, ATSP-7041 demonstrates robust p53-dependent tumor growth suppression in MDM2/MDMX-overexpressing xenograft cancer models, with a high correlation to on-target pharmacodynamic activity, and possesses favorable pharmacokinetic and tissue distribution properties. Overall, ATSP-7041 demonstrates in vitro and in vivo proof-of-concept that stapled peptides can be developed as therapeutically relevant inhibitors of protein-protein interaction and may offer a viable modality for cancer therapy.
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Jin L, Sturgis EM, Zhang Y, Huang Z, Wei P, Guo W, Wang Z, Wei Q, Song X, Li G. Genetic variants in p53-related genes confer susceptibility to second primary malignancy in patients with index squamous cell carcinoma of head and neck. Carcinogenesis 2013; 34:1551-7. [PMID: 23508638 DOI: 10.1093/carcin/bgt096] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Because of their important roles in mediating the stabilization and expression of p53, we hypothesized that high-risk genotypes of polymorphisms in p53-related genes, including p53, p73, p14(ARF), MDM2 and MDM4, may be associated with an increased risk of second primary malignancy (SPM) after index squamous cell carcinoma of the head and neck (SCCHN). We analyzed data from a cohort of 1283 patients with index SCCHN who were recruited between 1995 and 2007 at MD Anderson Cancer Center and followed for SPM development. Patients were genotyped for nine polymorphisms of p53-related genes. A log-rank test and Cox models were used to compare SPM-free survival and risk. Our results demonstrated that each p53-related polymorphism had a moderate effect on increased SPM risk, but when we combined risk genotypes of these nine polymorphisms together, we found that SPM-free survival was significantly shorter among risk groups with a greater number of combined risk genotypes. SPM risk increased with increasing number of risk genotypes (P < 0.0001 for trend). Compared with the low-risk group (0-3 combined risk genotypes), both the medium-risk (4-5 combined risk genotypes) and high-risk (6-9 combined risk genotypes) groups had significantly increased SPM risk [hazard ratio (HR): 1.6; 95% confidence interval (CI): 1.0-2.6 and HR: 3.0; 95% CI: 1.8-5.0, respectively]. Moreover, such significant associations were even higher in several subgroups. Our findings suggest that combined risk genotypes of p53-related genes may jointly modify SPM risk, especially in patients who are smokers and those with index non-oropharyngeal cancers. However, larger studies are needed to validate our findings.
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Affiliation(s)
- Lei Jin
- Department of Head & Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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25
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Fang M, Simeonova I, Bardot B, Lejour V, Jaber S, Bouarich-Bourimi R, Morin A, Toledo F. Mdm4 loss in mice expressing a p53 hypomorph alters tumor spectrum without improving survival. Oncogene 2013; 33:1336-9. [DOI: 10.1038/onc.2013.62] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/02/2013] [Accepted: 01/07/2013] [Indexed: 12/19/2022]
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Abstract
The p53 tumor suppressor is activated in response to cellular stresses to induce cell-cycle arrest, cellular senescence, and apoptosis. The p53 gene is inactivated by mutations in more than 50% of human tumors. In addition, tumor cells dampen p53 activities via overexpression of p53-negative regulators, in particular 2 structurally related proteins, Mdm2 and Mdm4. And yet, Mdm2 and Mdm4 possess p53-independent activities, which also contribute to tumor formation and progression. Given that Mdm2 and Mdm4 inhibit p53 activities to promote tumor development, small molecules and peptides were developed to abrogate the inhibition of p53 by Mdm proteins. Antitumor activities of these molecules have already been confirmed in preclinical studies and early-phase clinical trials. These research endeavors and clinical advances constitute the main focus of this review.
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Affiliation(s)
- Qin Li
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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27
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Shi D, Gu W. Dual Roles of MDM2 in the Regulation of p53: Ubiquitination Dependent and Ubiquitination Independent Mechanisms of MDM2 Repression of p53 Activity. Genes Cancer 2012; 3:240-8. [PMID: 23150757 DOI: 10.1177/1947601912455199] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
MDM2 oncogenic protein is the principal cellular antagonist of the p53 tumor suppresser gene. p53 activity needs exquisite control to elicit appropriate responses to differential cellular stress conditions. p53 becomes stabilized and active upon various types of stresses. However, too much p53 is not beneficial to cells and causes lethality. At the steady state, p53 activity needs to be leashed for cell survival. Early studies suggested that the MDM2 oncoprotein negatively regulates p53 activity through the induction of p53 protein degradation. MDM2 serves as an E3 ubiquitin ligase of p53; it catalyzes polyubiquitination and subsequently induces proteasome degradation to downregulate p53 protein level. However, the mechanism by which MDM2 represses p53 is not a single mode. Emerging evidence reveals another cellular location of MDM2-p53 interaction. MDM2 is recruited to chromatin, specifically the p53 responsive promoter regions, in a p53 dependent manner. MDM2 is proposed to directly inhibit p53 transactivity at chromatin. This article provides an overview of the mechanism by which p53 is repressed by MDM2 in both ubiquitination dependent and ubiquitination independent pathways.
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Affiliation(s)
- Dingding Shi
- Institute for Cancer Genetics, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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Zhuang C, Miao Z, Zhu L, Dong G, Guo Z, Wang S, Zhang Y, Wu Y, Yao J, Sheng C, Zhang W. Discovery, synthesis, and biological evaluation of orally active pyrrolidone derivatives as novel inhibitors of p53-MDM2 protein-protein interaction. J Med Chem 2012; 55:9630-42. [PMID: 23046248 DOI: 10.1021/jm300969t] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The p53-MDM2 interaction has been proved to be a valuable target to develop effective antitumor agents. Novel p53-MDM2 inhibitors bearing pyrrolidone scaffolds were successfully identified by structure-based design. The nanomolar inhibitor 5 possessed good p53-MDM2 inhibitory activity (K(i) = 780 nM) due to its hydrophobic and hydrogen bonding interactions with MDM2. Further hit optimization led to the discovery of a number of highly potent pyrrolidone derivatives with improved p53-MDM2 inhibitory activity and in vitro antiproliferative potency. Compounds 41 (K(i) = 260.0 nM) and 60a (K(i) = 150.0 nM) showed good and selective activity against tumor cells with deleted p53. In addition, these two compounds also effectively inhibited the tumor growth in the A549 xenograft model. Interestingly, compound 41 was proved to be a potent MDM2/MDMX dual inhibitor. The novel pyrrolidone p53-MDM2 inhibitors represent promising lead structures for the development of novel antitumor agents.
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Affiliation(s)
- Chunlin Zhuang
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People's Republic of China
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29
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Combination treatment in vitro with Nutlin, a small-molecule antagonist of MDM2, and pegylated interferon-α 2a specifically targets JAK2V617F-positive polycythemia vera cells. Blood 2012; 120:3098-105. [PMID: 22872685 DOI: 10.1182/blood-2012-02-410712] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Interferon (IFN-α) is effective therapy for polycythemia vera (PV) patients, but it is frequently interrupted because of adverse events. To permit the long-term use of IFN, we propose combining low doses of IFN with Nutlin-3, an antagonist of MDM2, which is also capable of promoting PV CD34(+) cell apoptosis. Combination treatment with subtherapeutic doses of Peg IFN-α 2a and Nutlin-3 inhibited PV CD34(+) cell proliferation by 50% while inhibiting normal CD34(+) cells by 30%. Combination treatment with Nutlin-3 and Peg IFN-α 2a inhibited PV colony formation by 55%-90% while inhibiting normal colony formation by 22%-30%. The combination of these agents also decreased the proportion of JAK2V617F-positive hematopoietic progenitor cells in 6 PV patients studied. Treatment with low doses of Peg IFN-α 2a combined with Nutlin-3 increased phospho-p53 and p21 protein levels in PV CD34(+) cells and increased the degree of apoptosis. These 2 reagents affect the tumor suppressor p53 through different pathways with Peg IFN-α 2a activating p38 MAP kinase and STAT1, leading to increased p53 transcription, whereas Nutlin-3 prevents the degradation of p53. These data suggest that treatment with low doses of both Nutlin-3 combined with Peg IFN-α 2a can target PV hematopoietic progenitor cells, eliminating the numbers of malignant hematopoietic progenitor cells.
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30
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Gembarska A, Luciani F, Fedele C, Russell EA, Dewaele M, Villar S, Zwolinska A, Haupt S, de Lange J, Yip D, Goydos J, Haigh JJ, Haupt Y, Larue L, Jochemsen A, Shi H, Moriceau G, Lo RS, Ghanem G, Shackleton M, Bernal F, Marine JC. MDM4 is a key therapeutic target in cutaneous melanoma. Nat Med 2012; 18:1239-47. [PMID: 22820643 DOI: 10.1038/nm.2863] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 06/13/2012] [Indexed: 12/22/2022]
Abstract
The inactivation of the p53 tumor suppressor pathway, which often occurs through mutations in TP53 (encoding tumor protein 53) is a common step in human cancer. However, in melanoma-a highly chemotherapy-resistant disease-TP53 mutations are rare, raising the possibility that this cancer uses alternative ways to overcome p53-mediated tumor suppression. Here we show that Mdm4 p53 binding protein homolog (MDM4), a negative regulator of p53, is upregulated in a substantial proportion (∼65%) of stage I-IV human melanomas and that melanocyte-specific Mdm4 overexpression enhanced tumorigenesis in a mouse model of melanoma induced by the oncogene Nras. MDM4 promotes the survival of human metastatic melanoma by antagonizing p53 proapoptotic function. Notably, inhibition of the MDM4-p53 interaction restored p53 function in melanoma cells, resulting in increased sensitivity to cytotoxic chemotherapy and to inhibitors of the BRAF (V600E) oncogene. Our results identify MDM4 as a key determinant of impaired p53 function in human melanoma and designate MDM4 as a promising target for antimelanoma combination therapy.
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Affiliation(s)
- Agnieszka Gembarska
- Center for the Biology of Disease, Laboratory for Molecular Cancer Biology, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium; Center for Human Genetics, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
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