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Snijders AM, Liu Y, Su L, Huang Y, Mao JH. Expression profiling reveals transcriptional regulation by Fbxw7/mTOR pathway in radiation-induced mouse thymic lymphomas. Oncotarget 2016; 6:44794-805. [PMID: 26575021 PMCID: PMC4792592 DOI: 10.18632/oncotarget.6328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/23/2015] [Indexed: 01/12/2023] Open
Abstract
The tumor suppressor gene FBXW7 is deleted and mutated in many different types of human cancers. FBXW7 primarily exerts its tumor suppressor activity by ubiquitinating different oncoproteins including mTOR. Here we used gene transcript profiling to gain a deeper understanding of the role of FBXW7 in tumor development and to determine the influence of mTOR inhibition by rapamycin on tumor transcriptome and biological functions. In comparison to tumors from p53 single heterozygous (p53+/−) mice, we find that radiation-induced thymic lymphomas from Fbxw7/p53 double heterozygous (Fbxw7+/−p53+/−) mice show significant deregulation of cholesterol metabolic processes independent of rapamycin treatment, while cell cycle related genes were upregulated in tumors from placebo treated Fbxw7+/−p53+/− mice, but not in tumors from rapamycin treated Fbxw7+/−p53+/− mice. On the other hand, tumors from rapamycin treated Fbxw7+/−p53+/− mice were enriched for genes involved in the integrated stress response, an adaptive mechanism to survive in stressful environments. Finally, we demonstrated that the Fbxw7 gene signatures identified in mouse tumors significantly overlap with FBXW7 co-expressed genes in human cancers. Importantly these common FBXW7 gene signatures between mouse and human are predictive for disease-free survival in human colon, breast and lung adenocarcinoma cancer patients. These results provide novel insights into the role of FBXW7 in tumor development and have identified a number of potential targets for therapeutic intervention.
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Affiliation(s)
- Antoine M Snijders
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yueyong Liu
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Li Su
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yurong Huang
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jian-Hua Mao
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Sato M, Rodriguez-Barrueco R, Yu J, Do C, Silva JM, Gautier J. MYC is a critical target of FBXW7. Oncotarget 2015; 6:3292-305. [PMID: 25669969 PMCID: PMC4413654 DOI: 10.18632/oncotarget.3203] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/18/2014] [Indexed: 12/22/2022] Open
Abstract
MYC deregulation is a driver of many human cancers. Altering the balance of MYC protein levels at the level of transcription, protein stability, or turnover is sufficient to transform cells to a tumorigenic phenotype. While direct targeting of MYC is difficult, specific genetic vulnerabilities of MYC-deregulated cells could be exploited to selectively inhibit their growth. Using a genome-wide shRNA screen, we identified 78 candidate genes, which are required for survival of human mammary epithelial cells with elevated MYC levels. Among the candidates, we validated and characterized FBXW7, a component of the SCF-like ubiquitin ligase complex that targets MYC for proteasomal degradation. Down-regulation of FBXW7 leads to synergistic accumulation of cellular and active chromatin-bound MYC, while protein levels of other FBXW7 targets appear unaffected. Over a four-week time course, continuous FBXW7 down-regulation and MYC activation together cause an accumulation of cells in S-phase and G2/M-phase of the cell cycle. Under these conditions, we also observe elevated chromatin-bound levels of CDC45, suggesting increased DNA replication stress. Consistent with these results, FBXW7 down-regulation alone decreases the survival of T47D breast cancer cells. These results establish that FBXW7 down-regulation is synthetic lethal with MYC, and that MYC is a critical target of FBXW7 in breast epithelial cells.
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Affiliation(s)
- Mai Sato
- Department of Pathology and Cell Biology, Columbia University, New York, USA
- Institute for Cancer Genetics, Columbia University, New York, USA
| | - Ruth Rodriguez-Barrueco
- Institute for Cancer Genetics, Columbia University, New York, USA
- Department of Pathology, Mount Sinai School of Medicine, New York, USA
| | - Jiyang Yu
- Department of Biomedical Informatics, Columbia University, New York, USA
| | - Catherine Do
- Institute for Cancer Genetics, Columbia University, New York, USA
| | - Jose M. Silva
- Department of Pathology and Cell Biology, Columbia University, New York, USA
- Institute for Cancer Genetics, Columbia University, New York, USA
- Department of Pathology, Mount Sinai School of Medicine, New York, USA
| | - Jean Gautier
- Institute for Cancer Genetics, Columbia University, New York, USA
- Department of Genetics and Development, Columbia University, New York, USA
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Gong J, Lv L, Huo J. Roles of F-box proteins in human digestive system tumors (Review). Int J Oncol 2014; 45:2199-207. [PMID: 25270675 DOI: 10.3892/ijo.2014.2684] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 09/16/2014] [Indexed: 12/16/2022] Open
Abstract
F-box proteins (FBPs), the substrate-recognition subunit of E3 ubiquitin (Ub) ligase, are the important components of Ub proteasome system (UPS). FBPs are involved in multiple cellular processes through ubiquitylation and subsequent degradation of their target proteins. Many studies have described the roles of FBPs in human cancers. Digestive system tumors account for a large proportion of all the tumors, and their mortality is very high. This review summarizes for the first time the roles of FBPs in digestive system tumorige-nesis and tumor progression, aiming at finding new routes for the rational design of targeted anticancer therapies in digestive system tumors.
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Affiliation(s)
- Jian Gong
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Liang Lv
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Jirong Huo
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
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Villaruz LC, Socinski MA. Temsirolimus therapy in a patient with lung adenocarcinoma harboring an FBXW7 mutation. Lung Cancer 2013; 83:300-1. [PMID: 24360397 DOI: 10.1016/j.lungcan.2013.11.018] [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: 09/30/2013] [Revised: 11/20/2013] [Accepted: 11/24/2013] [Indexed: 10/25/2022]
Abstract
We report the identification of an FBXW7 mutation in a patient with adenocarcinoma of the lung, whose tumor had previously been shown to be EGFR and ALK wild type and who had previously progressed on multiple lines of systemic therapy. She experienced both clinical and radiographic benefit from treatment with the mTOR inhibitor temsirolimus.
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Affiliation(s)
- Liza C Villaruz
- University of Pittsburgh Cancer Institute, University of Pittsburgh, School of Medicine/Hematology-Oncology, Lung and Thoracic Malignancies Program, Pittsburgh, PA 15232, United States.
| | - Mark A Socinski
- University of Pittsburgh Cancer Institute, University of Pittsburgh, School of Medicine/Hematology-Oncology, Lung and Thoracic Malignancies Program, Pittsburgh, PA 15232, United States
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Yokobori T, Yokoyama Y, Mogi A, Endoh H, Altan B, Kosaka T, Yamaki E, Yajima T, Tomizawa K, Azuma Y, Onozato R, Miyazaki T, Tanaka S, Kuwano H. FBXW7 mediates chemotherapeutic sensitivity and prognosis in NSCLCs. Mol Cancer Res 2013; 12:32-7. [PMID: 24165483 DOI: 10.1158/1541-7786.mcr-13-0341] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. To improve the prognosis of patients with NSCLCs, new and validated therapeutic targets are critically needed. In this study, we focused on F-box and WD repeat domain containing-7 (FBXW7), an E3 ubiquitin ligase, that regulates the degradation of MCL1, Myc, cyclin E, and TOP2A. Importantly, loss of FBXW7 was associated with increased sensitivity of tumors to a class I-specific histone deacetylase (HDAC) inhibitor, MS-275. Immunohistochemical analysis revealed increased expression of FBXW7 targets, MCL1 and TOP2A, in NSCLC tumors with low expression of FBXW7. Moreover, clinical specimens exhibiting low FBXW7 expression presented with more progressive cancer and significantly shorter cancer-specific survival than patients with high FBXW7 expression. Mechanistic study of NSCLC cell lines with silenced FBXW7 revealed enhanced MS-275 sensitivity and taxol resistance. Interestingly, taxol resistance was eliminated by MS-275 treatment, suggesting the potential of HDAC inhibitors for the treatment of aggressive taxol-resistant NSCLCs that lack FBXW7. IMPLICATIONS FBXW7 status impacts chemosensitivity and is a prognostic marker in NSCLCs. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/early/2013/12/19/1541-7786.MCR-13-0341/F1.large.jpg.
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Affiliation(s)
- Takehiko Yokobori
- Department of General Surgical Science, Graduate School of Medicine, Gunma University, 3-39-22 Showamachi, Maebashi 371-8511 Japan.
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Abstract
Fbw7 is a member of F-box family proteins, which constitute one subunit of Skp1, Cul1, and F-box protein (SCF) ubiquitin ligase complex. SCF(Fbw7) targets a set of well-known oncoproteins, including c-Myc, cyclin E, Notch, c-Jun, and Mcl-1, for ubiquitylation and degradation. Fbw7 provides specificity of the ubiquitylation of these substrate proteins via recognition of a consensus phosphorylated degron. Through regulation of several important proteins, Fbw7 controls diverse cellular processes, including cell-cycle progression, cell proliferation, differentiation, DNA damage response, maintenance of genomic stability, and neural cell stemness. As reduced Fbw7 expression level and loss-of-function mutations are found in a wide range of human cancers, Fbw7 is generally considered as a tumor suppressor. However, the exact mechanisms underlying Fbw7-induced tumor suppression is unclear. This review focuses on regulation network, biological functions, and genetic alteration of Fbw7 in connection with its role in cancer development.
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Affiliation(s)
- Yabin Cheng
- Department of Dermatology and Skin Science, University of British Columbia, Vancouver, V6H 3Z6, Canada
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Welcker M, Clurman BE. FBW7 ubiquitin ligase: a tumour suppressor at the crossroads of cell division, growth and differentiation. Nat Rev Cancer 2008; 8:83-93. [PMID: 18094723 DOI: 10.1038/nrc2290] [Citation(s) in RCA: 839] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
FBW7 (F-box and WD repeat domain-containing 7) is the substrate recognition component of an evolutionary conserved SCF (complex of SKP1, CUL1 and F-box protein)-type ubiquitin ligase. SCF(FBW7) degrades several proto-oncogenes that function in cellular growth and division pathways, including MYC, cyclin E, Notch and JUN. FBW7 is also a tumour suppressor, the regulatory network of which is perturbed in many human malignancies. Numerous cancer-associated mutations in FBW7 and its substrates have been identified, and loss of FBW7 function causes chromosomal instability and tumorigenesis. This Review focuses on structural and functional aspects of FBW7 and its role in the development of cancer.
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Affiliation(s)
- Markus Welcker
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
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Akhoondi S, Sun D, von der Lehr N, Apostolidou S, Klotz K, Maljukova A, Cepeda D, Fiegl H, Dafou D, Dofou D, Marth C, Mueller-Holzner E, Corcoran M, Dagnell M, Nejad SZ, Nayer BN, Zali MR, Hansson J, Egyhazi S, Petersson F, Sangfelt P, Nordgren H, Grander D, Reed SI, Widschwendter M, Sangfelt O, Spruck C. FBXW7/hCDC4 is a general tumor suppressor in human cancer. Cancer Res 2007; 67:9006-12. [PMID: 17909001 DOI: 10.1158/0008-5472.can-07-1320] [Citation(s) in RCA: 382] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ubiquitin-proteasome system is a major regulatory pathway of protein degradation and plays an important role in cellular division. Fbxw7 (or hCdc4), a member of the F-box family of proteins, which are substrate recognition components of the multisubunit ubiquitin ligase SCF (Skp1-Cdc53/Cullin-F-box-protein), has been shown to mediate the ubiquitin-dependent proteolysis of several oncoproteins including cyclin E1, c-Myc, c-Jun, and Notch. The oncogenic potential of Fbxw7 substrates, frequent allelic loss in human cancers, and demonstration that mutation of FBXW7 cooperates with p53 in mouse tumorigenesis have suggested that Fbxw7 could function as a tumor suppressor in human cancer. Here, we carry out an extensive genetic screen of primary tumors to evaluate the role of FBXW7 as a tumor suppressor in human tumorigenesis. Our results indicate that FBXW7 is inactivated by mutation in diverse human cancer types with an overall mutation frequency of approximately 6%. The highest mutation frequencies were found in tumors of the bile duct (cholangiocarcinomas, 35%), blood (T-cell acute lymphocytic leukemia, 31%), endometrium (9%), colon (9%), and stomach (6%). Approximately 43% of all mutations occur at two mutational "hotspots," which alter Arg residues (Arg465 and Arg479) that are critical for substrate recognition. Furthermore, we show that Fbxw7Arg465 hotspot mutant can abrogate wild-type Fbxw7 function through a dominant negative mechanism. Our study is the first comprehensive screen of FBXW7 mutations in various human malignancies and shows that FBXW7 is a general tumor suppressor in human cancer.
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Affiliation(s)
- Shahab Akhoondi
- Cancer Center Karolinska, Karolinska Hospital, Stockholm, Sweden
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Sgambato A, Cittadini A, Masciullo V, Di Salvatore M, Graziani C, Rettino A, Valdivieso P, Scambia G, Bianchino G, Zupa A, Improta G, Cifarelli RA. Low frequency of hCDC4 mutations in human primary ovarian cancer. Gynecol Oncol 2007; 105:553-5. [PMID: 17320938 DOI: 10.1016/j.ygyno.2007.01.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Accepted: 01/16/2007] [Indexed: 11/30/2022]
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