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Pu C, Liu Y, Deng R, Xu Q, Wang S, Zhang H, Luo D, Ma X, Tong Y, Li R. Development of PROTAC degrader probe of CDK4/6 based on DCAF16. Bioorg Chem 2023; 138:106637. [PMID: 37276679 DOI: 10.1016/j.bioorg.2023.106637] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 06/07/2023]
Abstract
Treatment of breast cancer has greatly evolved during the last decades, but triple negative breast cancer (TNBC) with a higher degree of malignancy cannot be directly and effectively treated. Abnormal cell cycle is generally found in human breast cancer and other malignant tumors, and cyclin-dependent kinases (CDK) 4/6, a cell cycle-related regulatory nuclear protein, is deemed as an effective target for breast cancer treatment so far. Since DCAF16 E3 ligase is also mainly distributed in the nucleus, in this study, by combining Palbociclib and DCAF16 E3 ligase ligand KB02 with different linkers, a series of DCAF16 based CDK4/6 degraders were designed and synthesized. Among them, compound A4 showed potent inhibitory activity against CDK4/6, and decreased the level of CDK4/6 protein in MDA-MB-231 cells in a concentration- and time-dependent manner. Moreover, the toxicity of A4 in normal cells showed 7 times lower than that of Palbociclib, and A4 exhibits therapeutic potential in MDA-MB-231 xenograft models in vivo. These findings indicate that A4, as a novel CDK4/6 degrader based on DCAF16, is worthy of further investigating for the treatment of TNBC.
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Affiliation(s)
- Chunlan Pu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; Medical Research Center, The Third People's Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Yuanyuan Liu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; Sichuan Center of Medical Product Technical Inspection, Chengdu 610041, China
| | - Rui Deng
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Qingjia Xu
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Shirui Wang
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Hongjia Zhang
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Dan Luo
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Xinyu Ma
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yu Tong
- West China Second University Hospital, Sichuan University, Key Laboratory of Birth Defects and Related Diseases of Women and Children Sichuan University, Ministry of Education, Chengdu, Sichuan Province, China.
| | - Rui Li
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
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CRL4A DTL degrades DNA-PKcs to modulate NHEJ repair and induce genomic instability and subsequent malignant transformation. Oncogene 2021; 40:2096-2111. [PMID: 33627782 PMCID: PMC7979543 DOI: 10.1038/s41388-021-01690-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 01/24/2021] [Accepted: 01/29/2021] [Indexed: 01/30/2023]
Abstract
Genomic instability induced by DNA damage and improper DNA damage repair is one of the main causes of malignant transformation and tumorigenesis. DNA double strand breaks (DSBs) are the most detrimental form of DNA damage, and nonhomologous end-joining (NHEJ) mechanisms play dominant and priority roles in initiating DSB repair. A well-studied oncogene, the ubiquitin ligase Cullin 4A (CUL4A), is reported to be recruited to DSB sites in genomic DNA, but whether it regulates NHEJ mechanisms of DSB repair is unclear. Here, we discovered that the CUL4A-DTL ligase complex targeted the DNA-PKcs protein in the NHEJ repair pathway for nuclear degradation. Overexpression of either CUL4A or DTL reduced NHEJ repair efficiency and subsequently increased the accumulation of DSBs. Moreover, we demonstrated that overexpression of either CUL4A or DTL in normal cells led to genomic instability and malignant proliferation. Consistent with the in vitro findings, in human precancerous lesions, CUL4A expression gradually increased with increasing malignant tendency and was negatively correlated with DNA-PKcs and positively correlated with γ-H2AX expression. Collectively, this study provided strong evidence that the CUL4A-DTL axis increases genomic instability and enhances the subsequent malignant transformation of normal cells by inhibiting NHEJ repair. These results also suggested that CUL4A may be a prognostic marker of precancerous lesions and a potential therapeutic target in cancer.
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Tam HW, Hall JR, Messenger ZJ, Jima DD, House JS, Linder K, Smart RC. C/EBPβ suppresses keratinocyte autonomous type 1 IFN response and p53 to increase cell survival and susceptibility to UVB-induced skin cancer. Carcinogenesis 2019; 40:1099-1109. [PMID: 30698678 PMCID: PMC10893916 DOI: 10.1093/carcin/bgz012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 01/04/2019] [Accepted: 01/22/2019] [Indexed: 12/14/2022] Open
Abstract
p53 is activated by DNA damage and oncogenic stimuli to regulate senescence, apoptosis and cell-cycle arrest, which are essential to prevent cancer. Here, we utilized UVB radiation, a potent inducer of DNA damage, p53, apoptosis and skin cancer to investigate the mechanism of CCAAT/enhancer binding protein-β (C/EBPβ) in regulating p53-mediated apoptosis in keratinocytes and to test whether the deletion of C/EBPβ in epidermis can protect mice from UVB-induced skin cancer. UVB-treatment of C/EBPβ skin conditional knockout (CKOβ) mice increased p53 protein levels in epidermis and enhanced p53-dependent apoptotic activity 3-fold compared with UVB-treated control mice. UVB increased C/EBPβ levels through a p53-dependent pathway and stimulated the formation of a C/EBPβ-p53 protein complex; knockdown of C/EBPβ increased p53 protein stability in keratinocytes. These results suggest a p53-C/EBPβ feedback loop, whereby C/EBPβ, a transcriptional target of a p53 pathway, functions as a survival factor by negatively regulating p53 apoptotic activity in response to DNA damage. RNAseq analysis of UVB-treated CKOβ epidermis unexpectedly revealed that type 1 interferon (IFN) pathway was the most highly enriched pathway. Numerous pro-apoptotic interferon stimulated genes were upregulated including some known to enhance p53 apoptosis. Our results indicate that p53 and IFN pathways function together in response to DNA damage to result in the activation of extrinsic apoptosis pathways and caspase 8 cleavage. Last, we observed CKOβ mice were resistant to UVB-induced skin cancer. Our results suggest that C/EBPβ represses apoptosis through keratinocyte autonomous suppression of the type 1 IFN response and p53 to increase cell survival and susceptibility to UVB-induced skin cancer.
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Affiliation(s)
- Hann W Tam
- Toxicology Program, North Carolina State University, Raleigh, NC, USA
| | - Jonathan R Hall
- Toxicology Program, North Carolina State University, Raleigh, NC, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | | | - Dereje D Jima
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - John S House
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - Keith Linder
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
- Department of Population Health and Pathobiology, North Carolina State University, Raleigh, NC, USA
| | - Robert C Smart
- Toxicology Program, North Carolina State University, Raleigh, NC, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
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Luczak MW, Krawic C, Zhitkovich A. p53 activation by Cr(VI): a transcriptionally limited response induced by ATR kinase in S-phase. Toxicol Sci 2019; 172:11-22. [PMID: 31388677 PMCID: PMC6813752 DOI: 10.1093/toxsci/kfz178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 07/19/2019] [Accepted: 07/26/2019] [Indexed: 01/30/2023] Open
Abstract
Cellular reduction of carcinogenic chromium(VI) causes several forms of Cr-DNA damage with different genotoxic properties. Chromate-treated cultured cells have shown a strong proapoptotic activity of the DNA damage-sensitive transcription factor p53. However, induction of p53 transcriptional targets by Cr(VI) in rodent lungs was weak or undetectable. We examined Cr(VI) effects on the p53 pathway in human cells with restored levels of ascorbate that acts as a principal reducer of Cr(VI) in vivo but is nearly absent in standard cell cultures. Ascorbate-restored H460 and primary human cells treated with Cr(VI) contained higher levels of p53 and its Ser15 phosphorylation, which were induced by ATR kinase. Cr(VI)-stimulated p53 phosphorylation occurred in S-phase by a diffusible pool of ATR that was separate from the chromatin-bound pool targeting DNA repair substrates at the sites of toxic mismatch repair of Cr-DNA adducts. Even when more abundantly present than after exposure to the radiomimetic bleomycin, Cr(VI)-stabilized p53 showed a much more limited activation of its target genes in two types of primary human cells. No increases in mRNA were found for nucleotide excision repair factors and a majority of proapoptotic genes. A weak transcription activity of Cr(VI)-upregulated p53 was associated with its low lysine acetylation in the regulatory C-terminal domain, resulting from the inability of Cr(VI) to activate ATM in ascorbate-restored cells. Thus, p53 activation by ascorbate-metabolized Cr(VI) represents a limited genome-protective response that is defective in upregulation of DNA repair genes and proapoptotic transcripts for elimination of damaged cells.
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Affiliation(s)
- Michal W Luczak
- Brown University, Department of Pathology and Laboratory Medicine, Providence, RI, USA
| | - Casey Krawic
- Brown University, Department of Pathology and Laboratory Medicine, Providence, RI, USA
| | - Anatoly Zhitkovich
- Brown University, Department of Pathology and Laboratory Medicine, Providence, RI, USA
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Liu H, Lu W, He H, Wu J, Zhang C, Gong H, Yang C. Inflammation-dependent overexpression of c-Myc enhances CRL4 DCAF4 E3 ligase activity and promotes ubiquitination of ST7 in colitis-associated cancer. J Pathol 2019; 248:464-475. [PMID: 30945288 DOI: 10.1002/path.5273] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/04/2019] [Accepted: 04/01/2019] [Indexed: 02/05/2023]
Abstract
Inflammation is well known as an important driver of the initiation of colitis-associated cancer (CAC). Some cytokines, such as IL-6 and TNF-α can activate expression of the oncogene c-Myc (MYC) and regulate its downstream effects. Cullin-RING E3 Ligases (CRLs) are emerging as master regulators controlling tumorigenesis. Here, we demonstrate that two cullin genes, CUL4A and CUL4B, but not other members, are specifically overexpressed in CAC tumour samples and positively correlate with levels of the proinflammatory cytokines IL-1β and IL-6. In vitro experiments revealed that the transcription factor c-Myc can specifically activate the expression of CUL4A and CUL4B by binding to a conserved site (CACGTG) located in their promoters. Additionally, we found that both CUL4A and CUL4B can form an E3 complex with DNA damage-binding protein 1 (DDB1) and DDB1-CUL4-associated factor 4 (DCAF4). In vitro and in vivo ubiquitination analyses indicate that CRL4DCAF4 E3 ligase specifically directs degradation of ST7 (suppression of tumorigenicity 7). Overexpression of c-Myc in human colon epithelial cells resulted in the accumulation of CUL4A, CUL4B and DCAF4, but degradation of ST7. In contrast, knockdown of c-Myc, CUL4A or CUL4B in the colon adenocarcinoma cell line HT29 caused accumulation of ST7 and inhibition of cell proliferation, colony formation ability and in vivo tumour growth. Collectively, our results provide in vitro and in vivo evidence that c-Myc regulates CRL4DCAF4 E3 ligase activity to mediate ubiquitination of ST7, whose presence is physiologically essential for CAC tumorigenesis. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Hong Liu
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
| | - Wenzhu Lu
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
| | - Hongbo He
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
| | - Jin Wu
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
| | - Caiguo Zhang
- Department of Dermatology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Hanlin Gong
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
| | - Chunmei Yang
- Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, Chengdu, China
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Huang F, Wang M, Liu R, Wang JZ, Schadt E, Haroutunian V, Katsel P, Zhang B, Wang X. CDT2-controlled cell cycle reentry regulates the pathogenesis of Alzheimer's disease. Alzheimers Dement 2019; 15:217-231. [PMID: 30321504 PMCID: PMC6758558 DOI: 10.1016/j.jalz.2018.08.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/07/2018] [Accepted: 08/31/2018] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Altered cell cycle reentry has been observed in Alzheimer's disease (AD). Denticleless (DTL) was predicted as the top driver of a cell cycle subnetwork associated with AD. METHODS We systematically investigated DTL expression in AD and studied the molecular, cellular, and behavioral endophenotypes triggered by DTL overexpression. RESULTS We experimentally validated that CDT2, the protein encoded by DTL, activated cyclin-dependent kinases through downregulating P21, which induced tau hyperphosphorylation and Aβ toxicity, two hallmarks of AD. We demonstrated that cyclin-dependent kinases inhibition by roscovitine not only rescued CDT2-induced cognitive defects but also reversed expression changes induced by DTL overexpression. RNA-seq data from the DTL overexpression experiments revealed the molecular mechanisms underlying CDT2 controlled cell cycle reentry in AD. DISCUSSION These findings provide new insights into the molecular mechanisms of AD pathogenesis and thus pave a way for developing novel therapeutics for AD by targeting AD specific cell cycle networks and drivers.
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Affiliation(s)
- Fang Huang
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Minghui Wang
- Department of Genetics and Genomic Sciences, Mount Sinai Center for Transformative Disease Modeling, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Rong Liu
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian-Zhi Wang
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Eric Schadt
- Department of Genetics and Genomic Sciences, Mount Sinai Center for Transformative Disease Modeling, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Vahram Haroutunian
- Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Psychiatry, JJ Peters VA Medical Center, Bronx, NY, USA; Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; The Alzheimer's Disease Research Center, Icahn School of Medicine at Mount Sinai, New York NY, USA
| | - Pavel Katsel
- Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bin Zhang
- Department of Genetics and Genomic Sciences, Mount Sinai Center for Transformative Disease Modeling, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, NY, USA.
| | - Xiaochuan Wang
- Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, JS, China.
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Yin Z, Li C, Wang J, Xue L. Myeloid-derived suppressor cells: Roles in the tumor microenvironment and tumor radiotherapy. Int J Cancer 2018; 144:933-946. [PMID: 29992569 DOI: 10.1002/ijc.31744] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 06/28/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Zhongnan Yin
- Biobank; Peking University Third Hospital; Beijing China
| | - Chunxiao Li
- Department of Radiation Oncology; Peking University Third Hospital; Beijing China
| | - Junjie Wang
- Department of Radiation Oncology; Peking University Third Hospital; Beijing China
| | - Lixiang Xue
- Biobank; Peking University Third Hospital; Beijing China
- Department of Radiation Oncology; Peking University Third Hospital; Beijing China
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Hernandez-Segura A, Brandenburg S, Demaria M. Induction and Validation of Cellular Senescence in Primary Human Cells. J Vis Exp 2018. [PMID: 29985363 DOI: 10.3791/57782] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a hallmark of various pathophysiological conditions including tumor suppression, tissue remodeling and aging. The inducers of cellular senescence in vivo are still poorly characterized. However, a number of stimuli can be used to promote cellular senescence ex vivo. Among them, most common senescence-inducers are replicative exhaustion, ionizing and non-ionizing radiation, genotoxic drugs, oxidative stress, and demethylating and acetylating agents. Here, we will provide detailed instructions on how to use these stimuli to induce fibroblasts into senescence. This protocol can easily be adapted for different types of primary cells and cell lines, including cancer cells. We also describe different methods for the validation of senescence induction. In particular, we focus on measuring the activity of the lysosomal enzyme Senescence-Associated β-galactosidase (SA-β-gal), the rate of DNA synthesis using 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, the levels of expression of the cell cycle inhibitors p16 and p21, and the expression and secretion of members of the Senescence-Associated Secretory Phenotype (SASP). Finally, we provide example results and discuss further applications of these protocols.
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Affiliation(s)
- Alejandra Hernandez-Segura
- European Research Institute for the Biology of Aging, University of Groningen, University Medical Center Groningen
| | - Simone Brandenburg
- European Research Institute for the Biology of Aging, University of Groningen, University Medical Center Groningen
| | - Marco Demaria
- European Research Institute for the Biology of Aging, University of Groningen, University Medical Center Groningen;
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Lu Y, Reyes J, Walter S, Gonzalez T, Medrano G, Boswell M, Boswell W, Savage M, Walter R. Characterization of basal gene expression trends over a diurnal cycle in Xiphophorus maculatus skin, brain and liver. Comp Biochem Physiol C Toxicol Pharmacol 2018; 208:2-11. [PMID: 29203320 PMCID: PMC5936649 DOI: 10.1016/j.cbpc.2017.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/10/2017] [Accepted: 11/28/2017] [Indexed: 12/20/2022]
Abstract
Evolutionarily conserved diurnal circadian mechanisms maintain oscillating patterns of gene expression based on the day-night cycle. Xiphophorus fish have been used to evaluate transcriptional responses after exposure to various light sources and it was determined that each source incites distinct genetic responses in skin tissue. However, basal expression levels of genes that show oscillating expression patterns in day-night cycle, may affect the outcomes of such experiments, since basal gene expression levels at each point in the circadian path may influence the profile of identified light responsive genes. Lack of knowledge regarding diurnal fluctuations in basal gene expression patterns may confound the understanding of genetic responses to external stimuli (e.g., light) since the dynamic nature of gene expression implies animals subjected to stimuli at different times may be at very different stages within the continuum of genetic homeostasis. We assessed basal gene expression changes over a 24-hour period in 200 select Xiphophorus gene targets known to transcriptionally respond to various types of light exposure. We identified 22 genes in skin, 36 genes in brain and 28 genes in liver that exhibit basal oscillation of expression patterns. These genes, including known circadian regulators, produced the expected expression patterns over a 24-hour cycle when compared to circadian regulatory genes identified in other species, especially human and other vertebrate animal models. Our results suggest the regulatory network governing diurnal oscillating gene expression is similar between Xiphophorus and other vertebrates for the three Xiphophorus organs tested. In addition, we were able to categorize light responsive gene sets in Xiphophorus that do, and do not, exhibit circadian based oscillating expression patterns.
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Affiliation(s)
- Yuan Lu
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Jose Reyes
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Sean Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Trevor Gonzalez
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Geraldo Medrano
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Mikki Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - William Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Markita Savage
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA
| | - Ronald Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, San Marcos, TX, USA.
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Zhang C, Chen B, Jiang K, Lao L, Shen H, Chen Z. Activation of TNF-α/NF-κB axis enhances CRL4B DCAF11 E3 ligase activity and regulates cell cycle progression in human osteosarcoma cells. Mol Oncol 2018; 12:476-494. [PMID: 29377600 PMCID: PMC5891038 DOI: 10.1002/1878-0261.12176] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/30/2017] [Accepted: 11/20/2017] [Indexed: 12/16/2022] Open
Abstract
Cullin 4B, a member of the Cullins, which serve as scaffolds to facilitate the assembly of E3 ligase complexes, is aberrantly expressed in many cancers, including osteosarcoma. Recently, we observed that CUL4B forms the CRL4BDCAF11 E3 ligase, which specifically ubiquitinates and degrades the cyclin‐dependent kinase (CDK) inhibitor p21Cip1 in human osteosarcoma cells. However, the underlying mechanisms regarding the aberrant expression of CUL4B and the upstream members of this signaling pathway are mostly unknown. In this study, we demonstrate that nuclear factor kappaB (NF‐κB) is a direct modulator of CUL4B expression. The CUL4B promoter is responsive to several NF‐κB subunits, including RelA, RelB, and c‐Rel, but not to p50 or p52. Additional studies reveal that the tumor necrosis factor alpha (TNF‐α)/NF‐κB axis pathway is activated in human osteosarcoma cells. This activation causes both CUL4B and NF‐κB subunits to become abundant in the nucleus of human osteosarcoma cells. The down‐regulation of individual genes, including TNFR1, RelA, RelB, c‐Rel, and CUL4B, or pairs of them, including TNFR1 + RelA,TNFR1 + RelB,TNFR1 + c‐Rel, and RelA+CUL4B, has similar effects on cell growth inhibition, colony formation, cell invasion, and in vivo tumor formation, whereas the overexpression of CUL4B in these knockdown cells significantly reverses their phenotypes. The inhibition of the TNF‐α/NF‐κB pathway greatly attenuates CRL4BDCAF11 E3 ligase activity and causes the accumulation of p21Cip1, thereby leading to cell cycle arrest at the S phase. Taken together, our results support a model in which the activation of the TNF‐α/NF‐κB axis contributes to an increase in CRL4BDCAF11 activity and a decrease in p21Cip1 protein levels, thereby controlling cell cycle progression in human osteosarcoma cells.
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Affiliation(s)
- Caiguo Zhang
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China.,Department of Dermatology, University of Colorado, Aurora, CO, USA
| | - Bin Chen
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China
| | - Kaibiao Jiang
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China
| | - Lifeng Lao
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China
| | - Hongxing Shen
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China
| | - Zhi Chen
- Department of Spine Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, China
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Wang Y, Gu X, Li W, Zhang Q, Zhang C. PAK1 overexpression promotes cell proliferation in cutaneous T cell lymphoma via suppression of PUMA and p21. J Dermatol Sci 2018; 90:60-67. [PMID: 29307600 DOI: 10.1016/j.jdermsci.2017.11.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/29/2017] [Accepted: 11/10/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND Cutaneous T cell lymphoma (CTCL) comprises a heterogeneous group of skin-homing T cell tumors. The small guanosine triphosphate effector p21-activated kinase 1 (PAK1) plays an important role in many fundamental cellular functions, including cell motility, proliferation, and apoptosis. The expression of PAK1 is up-regulated in several types of human cancers. However, little is known about the role of PAK1 in the pathogenesis of CTCL. OBJECTIVE The aim of this study was to evaluate the expression pattern and underlying mechanism of PAK1 in CTCL. METHODS Quantitative real-time polymerase chain reaction(qRT-PCR) was used to detect PAK1 mRNA expression in the peripheral blood mononuclear cells (PBMCs) of patients with CTCL. The expression of PAK1 protein in CTCL tumor tissues was determined by immunohistochemistry. CTCL cell lines were treated with a small molecule inhibitor of PAK1, p21-activated kinase inhibitor III (IPA3), at concentrations of 2, 3.5 and 5 μM for 24 h. Hut 78 and HH CTCL cells were transfected with lentiviral-based PAK1 gene knockdown vectors. We determined the effects of PAK1 knockdown on cell proliferation and apoptosis in CTCL cells by MTS assay and flow cytometry. Animal experiments were performed to investigate the effects of PAK1 knockdown on the growth of tumors in vivo. Transcriptomic sequencing was performed to detect the direct downstream targets of PAK1 silencing. Reverse transcription polymerase chain reaction and western blot analysis were applied to verify the results of the transcriptomic analysis. RESULTS We detected PAK1 overexpression in PBMCs and skin lesions from patients with CTCL compared with benign inflammatory dermatoses (BID). Knockdown of PAK1 inhibited cell proliferation and promoted spontaneous apoptosis. In addition, the inhibitory effect of IPA3 was validated in the CTCL cell lines. Additionally, mice injected with PAK1-silenced cells presented with a decreased rate of tumor growth compared with the control groups. Moreover, the mRNA and protein expression of PUMA (BBC3) and p21 (CDKN1A) were increased in PAK1-silenced Hut 78 and HH cells. CONCLUSIONS Our data indicated that PAK1 is upregulated in CTCL. PAK1 silencing induced apoptosis and inhibited cell growth by stimulating the expression of PUMA and p21. Thus, PAK1 may be a potential tumor marker and therapeutic target of CTCL.
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Affiliation(s)
- Yimeng Wang
- Department of Dermatology, Peking University Third Hospital, Beijing, China
| | - Xiaoguang Gu
- Department of Dermatology, Aviation General Hospital, Beijing, China
| | - Weiwei Li
- Department of Dermatology, Peking University Third Hospital, Beijing, China
| | - Qian Zhang
- Department of Dermatology, Peking University Third Hospital, Beijing, China
| | - Chunlei Zhang
- Department of Dermatology, Peking University Third Hospital, Beijing, China.
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12
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MicroRNA-300 Regulates the Ubiquitination of PTEN through the CRL4B DCAF13 E3 Ligase in Osteosarcoma Cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2017; 10:254-268. [PMID: 29499938 PMCID: PMC5768150 DOI: 10.1016/j.omtn.2017.12.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 12/18/2017] [Accepted: 12/18/2017] [Indexed: 12/24/2022]
Abstract
Cullins, critical members of the cullin-RING ubiquitin ligases (CRLs), are often aberrantly expressed in different cancers. However, the underlying mechanisms regarding aberrant expression of these cullins and the specific substrates of CRLs in different cancers are mostly unknown. Here, we demonstrate that overexpressed CUL4B in human osteosarcoma cells forms an E3 complex with DNA damage binding protein 1 (DDB1) and DDB1- and CUL4-associated factor 13 (DCAF13). In vitro and in vivo analyses indicated that the CRL4BDCAF13 E3 ligase specifically recognized the tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) for degradation, and disruption of this E3 ligase resulted in PTEN accumulation. Further analyses indicated that miR-300 directly targeted the 3' UTR of CUL4B, and DNA hypermethylation of a CpG island in the miR-300 promoter region contributed to the downregulation of miR-300. Interestingly, ectopic expression of miR-300 or treatment with 5-AZA-2'-deoxycytidine, a DNA methylation inhibitor, decreased the stability of CRL4BDCAF13 E3 ligase and reduced PTEN ubiquitination. By applying in vitro screening to identify small molecules that specifically inhibit CUL4B-DDB1 interaction, we found that TSC01131 could greatly inhibit osteosarcoma cell growth and could disrupt the stability of the CRL4BDCAF13 E3 ligase. Collectively, our findings shed new light on the molecular mechanism of CUL4B function and might also provide a new avenue for osteosarcoma therapy.
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13
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KSP inhibitor SB743921 inhibits growth and induces apoptosis of breast cancer cells by regulating p53, Bcl-2, and DTL. Anticancer Drugs 2017; 27:863-72. [PMID: 27379929 PMCID: PMC5010280 DOI: 10.1097/cad.0000000000000402] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Kinesin spindle protein (KSP) is a microtubule-associated motor protein that is specifically expressed by mitosis cells. It is highly expressed in various types of tumors including hematomalignances and solid tumors. Chemical KSP inhibition has become a novel strategy in the development of anticancer drugs. SB743921 is a selective inhibitor for KSP, which is a mitotic protein essential for cell-cycle progression. Although SB743921 has shown antitumor activities for several types of cancers and entered into clinical trials, its therapeutic effects on breast cancer and mechanisms have not been explored. In this study, we tested the antitumor activity of SB743921 in breast cancer cell lines and partly elucidated its mechanisms. KSP and denticleless E3 ubiquitin–protein ligase homolog (DTL) are overexpressed in breast cancer cells compared with no-cancer tissues. Chemical inhibition of KSP by SB743921 not only reduces proliferation but also induces cell-cycle arrest and leads to apoptosis in breast cancer cells. Treatment of MCF-7 and MDA-MB-231 breast cancer cell lines with SB743921 results in decreased ability of colony formation in culture. SB743921 treatment also causes a KSP accumulation in protein level that is associated with cell arrest. Furthermore, we showed that SB743921 treatment significantly reduces the expression of bcl-2 and cell cycle-related protein DTL, and upregulates p53 and caspase-3 in breast cancer cells. Taken together, these data indicated that SB743921 can be expected to be a novel treatment agent for breast cancers.
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14
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Wang L, Zhang R, You X, Zhang H, Wei S, Cheng T, Cao Q, Wang Z, Chen Y. The steady-state level of CDK4 protein is regulated by antagonistic actions between PAQR4 and SKP2 and involved in tumorigenesis. J Mol Cell Biol 2017; 9:409-421. [DOI: 10.1093/jmcb/mjx028] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/04/2017] [Indexed: 01/26/2023] Open
Affiliation(s)
- Lin Wang
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Rui Zhang
- Cancer Molecular Diagnostic Core Laboratory, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Xue You
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Huanhuan Zhang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Siying Wei
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Tingting Cheng
- Department of Clinical Medicine, Tongji University, Shanghai, China
| | - Qianqian Cao
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhenzhen Wang
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yan Chen
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
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15
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Chen X, Li L, Xu S, Bu W, Chen K, Li M, Gu H. Ultraviolet B radiation down-regulates ULK1 and ATG7 expression and impairs the autophagy response in human keratinocytes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 178:152-164. [PMID: 29154199 DOI: 10.1016/j.jphotobiol.2017.08.043] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/28/2017] [Accepted: 08/31/2017] [Indexed: 01/06/2023]
Abstract
Autophagy is a self-digestive pathway that helps to maintain cellular homeostasis, and many autophagy-related gene (ATG)s involved the regulation of the autophagy process. Ultraviolet light is a common stressor of skin, but it is unclear how autophagy is regulated after ultraviolet exposure in epidermal keratinocytes. Here, we found that the mRNAs of some key ATG genes such as ULK1, ATG5 and ATG7 exhibited significantly lower levels in the skin tissues of the face and chest with solar ultraviolet exposure, compared with perineal skin. Interestingly, UVB radiation down-regulated the expression of ULK1, ATG3 and ATG7, and it inhibited the autophagy flux via a mechanistic target of rapamycin (MTOR)-independent pathway in human keratinocytes. The inhibition of autophagy in UVB-treated keratinocytes cannot be restored by treatment with the MTOR-dependent autophagy inducer rapamycin. Importantly, UVB treatment perturbs the conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to LC3-II and LC3-II turnover in response to treatment with MTOR inhibitors (Torin 1 and pp242), as well as endoplasmic reticular stress (A23187 and tunicamycin), inositol pathway (L690,330) and autophagy inducers (resveratrol and STF62247). Our study demonstrates that UVB radiation down-regulates several key autophagy-related proteins and impairs the autophagy response in keratinocytes. This study demonstrates a linkage between autophagy and skin disorders associated with ultraviolet exposure.
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Affiliation(s)
- Xu Chen
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China
| | - Li Li
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China
| | - Song Xu
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China
| | - Wenbo Bu
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China
| | - Kun Chen
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China
| | - Min Li
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China.
| | - Heng Gu
- Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Institute of Dermatology, Chinese Academy of Medical Science, Peking Union Medical College, Nanjing, China.
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16
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A tumor suppressor role for C/EBPα in solid tumors: more than fat and blood. Oncogene 2017; 36:5221-5230. [PMID: 28504718 DOI: 10.1038/onc.2017.151] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/29/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022]
Abstract
The transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) plays a critical role during embryogenesis and is thereafter required for homeostatic glucose metabolism, adipogenesis and myeloid development. Its ability to regulate the expression of lineage-specific genes and induce growth arrest contributes to the terminal differentiation of several cell types, including hepatocytes, adipocytes and granulocytes. CEBPA loss of-function mutations contribute to the development of ~10% of acute myeloid leukemia (AML), stablishing a tumor suppressor role for C/EBPα. Deregulation of C/EBPα expression has also been reported in a variety of additional human neoplasias, including liver, breast and lung cancer. However, functional CEBPA mutations have not been found in solid tumors, suggesting that abrogation of C/EBPα function in non-hematopoietic tissues is regulated by alternative mechanisms. Here we review the function of C/EBPα in solid tumors and focus on the molecular mechanisms underlying its tumor suppressive role.
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17
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Impact on Autophagy and Ultraviolet B Induced Responses of Treatment with the MTOR Inhibitors Rapamycin, Everolimus, Torin 1, and pp242 in Human Keratinocytes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:5930639. [PMID: 28400912 PMCID: PMC5376460 DOI: 10.1155/2017/5930639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/15/2017] [Accepted: 02/13/2017] [Indexed: 12/21/2022]
Abstract
The mechanistic target of Rapamycin (MTOR) protein is a crucial signaling regulator in mammalian cells that is extensively involved in cellular biology. The function of MTOR signaling in keratinocytes remains unclear. In this study, we detected the MTOR signaling and autophagy response in the human keratinocyte cell line HaCaT and human epidermal keratinocytes treated with MTOR inhibitors. Moreover, we detected the impact of MTOR inhibitors on keratinocytes exposed to the common carcinogenic stressors ultraviolet B (UVB) and UVA radiation. As a result, keratinocytes were sensitive to the MTOR inhibitors Rapamycin, everolimus, Torin 1, and pp242, but the regulation of MTOR downstream signaling was distinct. Next, autophagy induction only was observed in HaCaT cells treated with Rapamycin. Furthermore, we found that MTOR signaling was insensitive to UVB but sensitive to UVA radiation. UVB treatment also had no impact on the inhibition of MTOR signaling by MTOR inhibitors. Finally, MTOR inhibition by Rapamycin, everolimus, or pp242 did not affect the series of biological events in keratinocytes exposed to UVB, including the downregulation of BiP and PERK, activation of Histone H2A and JNK, and cleavage of caspase-3 and PARP. Our study demonstrated that MTOR inhibition in keratinocytes cannot always induce autophagy, and the MTOR pathway does not play a central role in the UVB triggered cellular response.
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18
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Sang Y, Yan F, Ren X. The role and mechanism of CRL4 E3 ubiquitin ligase in cancer and its potential therapy implications. Oncotarget 2016; 6:42590-602. [PMID: 26460955 PMCID: PMC4767455 DOI: 10.18632/oncotarget.6052] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/23/2015] [Indexed: 12/21/2022] Open
Abstract
CRLs (Cullin-RING E3 ubiquitin ligases) are the largest E3 ligase family in eukaryotes, which ubiquitinate a wide range of substrates involved in cell cycle regulation, signal transduction, transcriptional regulation, DNA damage response, genomic integrity, tumor suppression and embryonic development. CRL4 E3 ubiquitin ligase, as one member of CRLs family, consists of a RING finger domain protein, cullin4 (CUL4) scaffold protein and DDB1–CUL4 associated substrate receptors. The CUL4 subfamily includes two members, CUL4A and CUL4B, which share extensively sequence identity and functional redundancy. Aberrant expression of CUL4 has been found in a majority of tumors. Given the significance of CUL4 in cancer, understanding its detailed aspects of pathogenesis of human malignancy would have significant value for the treatment of cancer. Here, the work provides an overview to address the role of CRL4 E3 ubiquitin ligase in cancer development and progression, and discuss the possible mechanisms of CRL4 ligase involving in many cellular processes associated with tumor. Finally, we discuss its potential value in cancer therapy.
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Affiliation(s)
- Youzhou Sang
- Department of Immunology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Fan Yan
- Department of Immunology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Xiubao Ren
- Department of Biotherapy, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center of Cancer, Tianjin, China.,Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
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19
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Liu Y, Mallampalli RK. Small molecule therapeutics targeting F-box proteins in cancer. Semin Cancer Biol 2015; 36:105-19. [PMID: 26427329 DOI: 10.1016/j.semcancer.2015.09.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/12/2022]
Abstract
The ubiquitin proteasome system (UPS) plays vital roles in maintaining protein equilibrium mainly through proteolytic degradation of targeted substrates. The archetypical SCF ubiquitin E3 ligase complex contains a substrate recognition subunit F-box protein that recruits substrates to the catalytic ligase core for its polyubiquitylation and subsequent proteasomal degradation. Several well-characterized F-box proteins have been demonstrated that are tightly linked to neoplasia. There is mounting information characterizing F-box protein-substrate interactions with the rationale to develop unique therapeutics for cancer treatment. Here we review that how F-box proteins function in cancer and summarize potential small molecule inhibitors for cancer therapy.
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Affiliation(s)
- Yuan Liu
- Department of Medicine, The Acute Lung Injury, Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - Rama K Mallampalli
- Department of Medicine, The Acute Lung Injury, Center of Excellence, University of Pittsburgh, Pittsburgh, PA 15213, United States; Medical Specialty Service Line, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15240, United States.
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