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TRAF6 Promoted Tumor Glycolysis in Non-Small-Cell Lung Cancer by Activating the Akt-HIF α Pathway. BIOMED RESEARCH INTERNATIONAL 2021; 2021:3431245. [PMID: 34409101 PMCID: PMC8367595 DOI: 10.1155/2021/3431245] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/15/2021] [Indexed: 12/20/2022]
Abstract
TRAF6 has been reported to be associated with poor prognosis in non-small-cell lung cancer (NSCLC). However, its precise role in tumor development has not been elaborated. In the present study, the function and the mechanism by which TRAF6 contributes to development were intensively investigated. TRAF6 was found to be overexpressed in primary NSCLC tumor tissue and all tested cell lines. Knockdown of TRAF6 with shRNA substantially attenuated NSCLC cell proliferation and anchorage-independent growth. Moreover, tumor glycolysis, such as glucose consumption and lactate production, also significantly impaired. In TRAF6-deficient cells, hexokinase-2 expression was significantly reduced, which was caused by the decrease of HIF-1α transcriptional activity. Further investigations demonstrated that TRAF6 played an important role in the regulation of Akt activation, and exogenous overexpression of constitutively activated Akt substantially rescued glycolysis suppression in TRAF6 knockdown cells. The results of the xenograft model confirmed that downregulation of TRAF6 in NSCLC tumor cells dramatically restrained tumor growth in vivo. Taken together, our studies revealed the mechanism by which TRAF6 exerts its role in NSCLC development and suggested TRAF6 maybe was a promising candidate target for lung cancer prevention and therapy.
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LaPlante G, Zhang W. Targeting the Ubiquitin-Proteasome System for Cancer Therapeutics by Small-Molecule Inhibitors. Cancers (Basel) 2021; 13:3079. [PMID: 34203106 PMCID: PMC8235664 DOI: 10.3390/cancers13123079] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 12/14/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) is a critical regulator of cellular protein levels and activity. It is, therefore, not surprising that its dysregulation is implicated in numerous human diseases, including many types of cancer. Moreover, since cancer cells exhibit increased rates of protein turnover, their heightened dependence on the UPS makes it an attractive target for inhibition via targeted therapeutics. Indeed, the clinical application of proteasome inhibitors in treatment of multiple myeloma has been very successful, stimulating the development of small-molecule inhibitors targeting other UPS components. On the other hand, while the discovery of potent and selective chemical compounds can be both challenging and time consuming, the area of targeted protein degradation through utilization of the UPS machinery has seen promising developments in recent years. The repertoire of proteolysis-targeting chimeras (PROTACs), which employ E3 ligases for the degradation of cancer-related proteins via the proteasome, continues to grow. In this review, we will provide a thorough overview of small-molecule UPS inhibitors and highlight advancements in the development of targeted protein degradation strategies for cancer therapeutics.
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Affiliation(s)
- Gabriel LaPlante
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, 50 Stone Rd E, Guelph, ON N1G2W1, Canada;
| | - Wei Zhang
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, 50 Stone Rd E, Guelph, ON N1G2W1, Canada;
- CIFAR Azrieli Global Scholars Program, Canadian Institute for Advanced Research, MaRS Centre West Tower, 661 University Avenue, Toronto, ON M5G1M1, Canada
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Zhu M, Cao S, Zheng W, Zhai M, Wang M, Blair HT, Morris ST, Zhang H, Zhao Z. miR-509-5p anti-infection response for mycoplasma pneumonia in sheep by targeting NF-κB pathway. Vet Immunol Immunopathol 2021; 238:110275. [PMID: 34153741 DOI: 10.1016/j.vetimm.2021.110275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/10/2021] [Accepted: 05/25/2021] [Indexed: 11/16/2022]
Abstract
MicroRNAs play a key role in Mannan-binding lectin-mediated resistance to Mycoplasma ovipneumoniae pneumonia, by regulating the translation of mRNAs of target genes, thereby regulating the immune response. Additionally, TRAF6 is a key molecule in Toll-like receptor signal transduction, which mediates inflammation and apoptosis signaling pathways and is widely involved in inflammation and immune response. While the molecular regulation mechanism has not been reported. In this study, we screened differentially expressed miRNAs and genes of Anti-infection for M. pneumonia on Sheep, through relevant bioinformatics analysis. Further, the effect of differential expression of NF-κB signaling pathway related genes on the molecular mechanism of M. pneumonia was detected. We used miRNA-mRNA integrated analysed, the target gene TRAF6 of miR-509-5p was selected. TRAF6 dual luciferase reporter vector was co-transfected into HEK 293T cells and primary sheep respiratory mucosal epithelial cells to detect changes in luciferase activity. qRT-PCR was used to analyze the effect of miR-509-5p on the expression and regulation of TRAF6 and other genes related to the NF-κB signaling pathway. The result confirmed that TRAF6 was a target gene of miR-509-5p. Compared with miR-509-5p-NC group, the luciferase activity of miR-509-5p group was significantly down-regulated (P < 0.01). Further, in sheep respiratory mucosal epithelial cells, miR-509-5p mimic could significantly down-regulate the fold change value of TRAF6 (P < 0.01). On the contrary, miR-509-5p-inhibitor up-regulated the fold change value of TRAF6 (P < 0.05). Interestingly, the expression levels of other genes were different. Among them, miR-509-5p mimic significantly up-regulated TLR4 and IRAK4 (P < 0.05), significantly down-regulated TAK1 (P < 0.05) and NF-κB (P < 0.01). miR-509-5p-inhibitor significantly up-regulated NF-κB (P < 0.05) and TAK1 (P < 0.01). miR-509-5p targets TRAF6 to affect the expression of downstream genes, which negatively regulates the NF-κB pathway, thereby affecting the inflammatory response.
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Affiliation(s)
- Mengting Zhu
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China; State Key Laboratory of Sheep Genetic Improvement and Healthy Production, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi, China
| | - Shaoqi Cao
- Xinjiang Uygur Autonomous Region Animal Husbandry General Station, Urumqi, Xinjiang, 830001, China
| | - Wei Zheng
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Mengting Zhai
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Mingyuan Wang
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Hugh T Blair
- Institute Veterinary, Animal & Biomedical Sciences, Massey University, Auckland, Palmerston North, New Zealand
| | - Stephen Todd Morris
- Institute Veterinary, Animal & Biomedical Sciences, Massey University, Auckland, Palmerston North, New Zealand
| | - Hongmei Zhang
- First Affiliated Hospital, School of Medical College, Shihezi University, Shihezi, Xinjiang, 832008, China.
| | - Zongsheng Zhao
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China.
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Abstract
Tumor necrosis factor receptor (TNFR)-related factors (TRAFs) are important linker molecules in the tumor necrosis factor superfamily (TNFSF) and the Toll-like/interleukin-1 receptor (TLR/ILR) superfamily. There are seven members: TRAF1-TRAF7, among those members, tumor necrosis factor receptor-associated factor 6 (TRAF6) is upregulated in various tumors, which has been related to tumorigenesis and development. With the in-depth study of the relationship between TRAF6 and different types of tumors, TRAF6 has oncogenic characteristics involved in tumorigenesis, tumor development, invasion, and metastasis through various signaling pathways, therefore, targeting TRAF6 has provided a novel strategy for tumor treatment. This review summarizes and analyzes the role of TRAF6 in tumorigenesis and tumor development in combination with the current research on TRAF6 and tumors.
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Sipos F, Kiss AL, Constantinovits M, Tulassay Z, Műzes G. Modified Genomic Self-DNA Influences In Vitro Survival of HT29 Tumor Cells via TLR9- and Autophagy Signaling. Pathol Oncol Res 2019; 25:1505-1517. [PMID: 30465163 DOI: 10.1007/s12253-018-0544-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 11/16/2018] [Indexed: 02/08/2023]
Abstract
In relation of immunobiology, the consequence of the crosstalk between TLR9-signaling and autophagy is poorly documented in HT29 cancer cells. To assess the TLR9-mediated biologic effects of modified self-DNA sequences on cell kinetics and autophagy response HT29 cells were incubated separately with intact genomic (g), hypermethylated (m), fragmented (f), and hypermethylated/fragmented (m/f) self-DNAs. Cell viability, apoptosis, cell proliferation, colonosphere-formation were determined. Moreover, the relation of TLR9-signaling to autophagy response was assayed by real-time RT-PCR, immunocytochemistry and transmission electron microscopy (TEM). After incubation with g-, m-, and m/f-DNAs cell viability and proliferation decreased, while apoptosis increased. F-DNA treatment resulted in an increase of cell survival. Methylation of self-DNA resulted in decrease of TLR9 expression, while it did not influence the positive effect of DNA fragmentation on MyD88 and TRAF6 overexpression, and TNFα downregulation. Fragmentation of DNA abrogated the positive effect of methylation on IRAK2, NFκB and IL-8 mRNA upregulations. In case of the autophagy genes and proteins, g- and f-DNAs caused significant upregulation of Beclin1, Atg16L1, and LC3B. According to TEM analyses, autophagy was present in each group of tumor cells, but to a varying degree. Incubation with m-DNA suppressed tumor cell survival by inducing features of apoptotic cell death, and activated mitophagy. F-DNA treatment enhanced cell survival, and activated macroautophagy and lipophagy. Colonospheres were only present after m-DNA incubation. Our data provided evidence for a close existing interplay between TLR9-signaling and the autophagy response with remarkable influences on cell survival in HT29 cells subjected to modified self-DNA treatments.
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Affiliation(s)
- Ferenc Sipos
- 2nd Department of Internal Medicine, Semmelweis University, Szentkirályi street 46, Budapest, 1088, Hungary.
| | - Anna L Kiss
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Miklós Constantinovits
- 2nd Department of Internal Medicine, Semmelweis University, Szentkirályi street 46, Budapest, 1088, Hungary
| | - Zsolt Tulassay
- 2nd Department of Internal Medicine, Semmelweis University, Szentkirályi street 46, Budapest, 1088, Hungary
- Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, 1051, Hungary
| | - Györgyi Műzes
- 2nd Department of Internal Medicine, Semmelweis University, Szentkirályi street 46, Budapest, 1088, Hungary
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TRAF6 is a novel NS3-interacting protein that inhibits classical swine fever virus replication. Sci Rep 2017; 7:6737. [PMID: 28751780 PMCID: PMC5532216 DOI: 10.1038/s41598-017-06934-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/21/2017] [Indexed: 12/31/2022] Open
Abstract
Classical swine fever virus (CSFV) non-structural protein 3 (NS3) is a multifunctional non-structural protein that plays a major role in viral replication. However, how exactly NS3 exerts these functions remains unknown. Here, we identified tumour necrosis factor receptor-associated factor 6 (TRAF6) as a novel NS3-interacting protein via yeast two-hybrid analysis, co-immunoprecipitation, and glutathione S-transferase pull-down assays. Furthermore, we observed that TRAF6 overexpression significantly inhibited CSFV replication, and TRAF6 knockdown promoted CSFV replication in porcine alveolar macrophages. Additionally, TRAF6 was degraded during CSFV infection or NS3 expression exclusively, indicating that CSFV and TRAF6 were mutually antagonistic and that TRAF6 degradation might contribute to persistent CSFV replication. Moreover, nuclear factor-kappa B (NF-κB) activity and interferon (IFN)-β and interleukin (IL)-6 expression were increased in TRAF6-overexpressing cells, whereas TRAF6-knockdown cells exhibited decreased NF-κB activity and IFN-β and IL-6 levels. Notably, TRAF6 overexpression did not reduce CSFV replication following inhibition of NF-κB activation by p65 knockdown. Our findings revealed that TRAF6 inhibits CSFV replication via activation of NF-κB-signalling pathways along with increases in the expression of its targets IFN-β and IL-6. This work addresses a novel aspect concerning the regulation of innate antiviral immune response during CSFV infection.
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Shen H, Li L, Yang S, Wang D, Zhou S, Chen X, Tang J. Regulatory role of tumor necrosis factor receptor-associated factor 6 in breast cancer by activating the protein kinase B/glycogen synthase kinase 3β signaling pathway. Mol Med Rep 2017. [DOI: 10.3892/mmr.2017.6782] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Huang H, Sun Z, Wang X, Liu X, Na W, Xu R, Ding R, Liu H. The effect of marrow stromal cells on TRAF6 expression levels in myeloma cells. Oncol Lett 2017; 14:1464-1470. [PMID: 28789366 PMCID: PMC5529903 DOI: 10.3892/ol.2017.6322] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 01/06/2017] [Indexed: 12/23/2022] Open
Abstract
Tumor necrosis factor receptor-associated factor 6 (TRAF6) is an important E3 ubiquitin ligase, which is key to immunity. TRAF6 has been implicated in the invasive growth and metastasis of various types of cancer, including squamous cell carcinoma, gastric cancer, myelodysplastic syndromes and acute myeloid leukemia. In the present study, associations between multiple myeloma (MM) and TRAF6, its downstream component nuclear factor-κB (NF-κB) and bone marrow stromal cells (MSC) were investigated. The TRAF6 protein expression levels of 18 patients were positively correlated with the protein levels of β-2 microglobulin (r2=0.3472; P=0.01) and negatively correlated with albumin protein levels (r2=0.5494; P=0.0004). In vitro expression of the TRAF6 protein, phosphorylated transcription factor p65 and phosphorylated p100 in myeloma cell lines was induced by MSCs from patients with MM. In addition, the in vitro expression of TRAF6 was associated with an enhanced proliferation rate of myeloma cells, which was blocked by silencing TRAF6 using small interfering RNA. Due to the association between the TRAF6-NF-κB signaling pathway in myeloma cells and MSCs, this signaling pathway may be a useful prognostic and therapeutic target in myeloma.
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Affiliation(s)
- Hongming Huang
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Zhongwei Sun
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Xudong Wang
- Surgical Comprehensive Laboratory, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Xinxin Liu
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Wenxiu Na
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Ruirong Xu
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Runsheng Ding
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Hong Liu
- Department of Hematology, The Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
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Liu Z, Liao L, Cao Z, Chen X, Du J. Synergisic effect of APRIL knockdown and Jiedu Xiaozheng Yin, a Chinese medicinal recipe, on the inhibition of hepatocellular carcinoma cell proliferation. Oncol Rep 2016; 37:754-760. [PMID: 28035399 PMCID: PMC5355738 DOI: 10.3892/or.2016.5339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/01/2016] [Indexed: 12/24/2022] Open
Abstract
It is well documented that A proliferation-inducing ligand (APRIL), a member of the tumor necrosis factor superfamily, plays a crucial role in the occurrence and development of tumors. In the present study, we evaluated the synergistic effect of APRIL knockdown and Jiedu Xiaozheng Yin (JXY), a Traditional Chinese Medicinal recipe, on the inhibition of hepatocellular carcinoma (HCC) cell proliferation and elucidated the underlying mechanism. The results demonstrated that both APRIL knockdown using small interfering RNA (siRNA) and JXY treatment could trigger cell cycle arrest and cell apoptosis, and suppress HCC cell proliferation through an NF-κB-related pathway. Synergism was further demonstrated between APRIL knockdown and JXY treatment. In conclusion, these results indicate that APRIL is a target gene for HCC and combination of siRNA-APRIL and JXY application holds great promise as a novel approach for the treatment of APRIL-positive HCC.
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Affiliation(s)
- Zhizhen Liu
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China
| | - Lianming Liao
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China
| | - Zhiyun Cao
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China
| | - Xuzheng Chen
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China
| | - Jian Du
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China
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Lin G, Huang C, Su G, Hu H, Xu H, Huang C. [Effect of TRAF6 Downregulation on Malignant Biological Behavior of
Lung Cancer Cell Lines]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2016; 18:661-7. [PMID: 26582220 PMCID: PMC6000311 DOI: 10.3779/j.issn.1009-3419.2015.11.01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
背景与目的 已有的研究提示肿瘤坏死因子受体相关因子6(tumor necrosis factor receptor-associated factor 6, TRAF6)在肺癌中常常扩增,可能扮演癌基因角色,但TRAF6的确切作用尚未充分阐明。本研究探索TRAF6表达对肺癌细胞株的增殖、凋亡、细胞周期、迁移及侵袭能力的影响以及可能作用机制。 方法 选用A549、H1650、SPC-A-1以及Calu-3等四种肺癌细胞株,应用蛋白印迹、qRT-PCR检测其TRAF6蛋白及mRNA表达。SPC-A-1、Calu-3细胞转染TRAF6 siRNA,以EMSA方法检测不同处理组核因子-κB的DNA结合活性,MTS法检测细胞增殖,流式细胞仪PI染色检测细胞凋亡,流式细胞仪进行细胞周期测定,划痕实验及Transwell小室法检测细胞迁移及侵袭能力,并应用蛋白印迹检测泛素化抗体、p65、CD24、CXCR4等蛋白表达。SPC-A-1细胞提取DNA后,应用二代测序法进行全基因组测序。 结果 在四种细胞株中,SPC-A-1和Calu-3细胞TRAF6相对高表达,TRAF6发生自身K63-泛素化,但仅在SPC-A-1细胞中观察到核因子-κB组成性活化。转染TRAF6 siRNA后,SPC-A-1、Calu-3细胞TRAF6表达明显下调,与空白组及对照组相比,下调TRAF6表达可抑制SPC-A-1细胞核因子-κB活性、降低迁移及侵袭能力以及促进细胞凋亡,CD24和CXCR4的表达也明显下调,但对细胞增殖及细胞周期无明显影响。下调TRAF6表达对Calu-3细胞株的核因子-κB活性、细胞增殖、凋亡、细胞周期、迁移及侵袭能力等均无明显影响。未发现SPC-A-1细胞株TRAF6基因突变或拷贝数改变。 结论 下调TRAF6表达可抑制SPC-A-1细胞迁移及侵袭能力,促进细胞凋亡,并且TRAF6可能是通过调控核因子-κB-CD24/CXCR4信号通路参与调控肺癌侵袭、细胞凋亡。
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Affiliation(s)
- Gen Lin
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
| | - Chuangzhong Huang
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
| | - Guangjian Su
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
| | - Huihua Hu
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
| | - Haipeng Xu
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
| | - Cheng Huang
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou 350014, China
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Dai YH, Hung LY, Chen RY, Lai CH, Chang KC. ON 01910.Na inhibits growth of diffuse large B-cell lymphoma by cytoplasmic sequestration of sumoylated C-MYB/TRAF6 complex. Transl Res 2016; 175:129-143.e13. [PMID: 27150054 DOI: 10.1016/j.trsl.2016.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/02/2016] [Accepted: 04/05/2016] [Indexed: 12/24/2022]
Abstract
Diffuse large B-cell lymphoma (DLBCL), the most common lymphoma, shows either no response or development of resistance to further treatment in 30% of the patients that warrants the development of novel drugs. We have reported that ON 01910.Na (rigosertib), a multikinase inhibitor, is selectively cytotoxic for DLBCL and induces more hyperphosphorylation and sumoylation of Ran GTPase-activating protein 1 (RanGAP1) in DLBCL cells than in non-neoplastic lymphoblastoid cell line. However, the exact mechanism of rigosertib-induced cell death in DLBCL remains to be clarified. Here, we analyzed the efficacy of rigosertib against DLBCL cells in vitro and in vivo and its molecular effects on tumor biology. We found for the first time that rigosertib attenuated expression of unmodified and sumoylated tumor necrosis factor receptor-associated factor 6 (TRAF6) and c-Myb and inhibited nuclear entry of sumoylated RanGAP1, TRAF6, and c-Myb that was confirmed by immunofluorescence. Moreover, co-immunoprecipitation showed that rigosertib induced sequestration of c-Myb and TRAF6 in the cytoplasm by stimulating their sumoylation through the RanGAP1*SUMO1/Ubc9 pathway. Specific knockdown of c-Myb and TRAF6 induced tumor cell apoptosis and cell cycle arrest at G1 phase. Xenograft mice bearing lymphoma cells also exhibited effective tumor regression on rigosertib treatment along with cytoplasmic expression of c-Myb and TRAF6. Nuclear expression of c-Myb in clinical cases of DLBCL correlated with a poor prognosis. Thus, suppression of c-Myb and TRAF6 activity may have therapeutic implication in DLBCL. These data support the clinical development of rigosertib in DLBCL.
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Affiliation(s)
- Yi-Han Dai
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Liang-Yi Hung
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Ruo-Yu Chen
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Chien-Hsien Lai
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Kung-Chao Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Pathology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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Liu W, Qi Y, Liu L, Tang Y, Wei J, Zhou L. Suppression of tumor cell proliferation by quinine via the inhibition of the tumor necrosis factor receptor‑associated factor 6‑AKT interaction. Mol Med Rep 2016; 14:2171-9. [PMID: 27430155 DOI: 10.3892/mmr.2016.5492] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 04/06/2016] [Indexed: 11/05/2022] Open
Abstract
Protein kinase B (AKT), is a pivotal component of pathways associated with cell survival, metabolism, invasion and metastasis. AKT mediates anti‑apoptotic and proliferative signaling in response to essential cytokines. Tumor necrosis factor receptor‑associated factor (TRAF)6, an E3 ubiquitin ligase, has been shown to ubiquitylate, as well as activate AKT. The present study used computational methods to determine the relevant amino acid residues at the binding site of TRAF6 and selected small molecules, which may bind to TRAF6. An ex vivo assay was performed to determine their antitumor activities and the possible mechanism of action. Quinine, a natural alkaloid that is well‑known for its therapeutic treatment of malaria, exhibited a distinct antiproliferative and pro‑apoptotic effect in HeLa and A549 tumor cell lines via the inhibition of the antiapoptotic protein, B‑cell lymphoma (BCL)‑2, and activation of the pro‑apoptotic factor, BCL‑2‑associated X protein. Quinine inhibited the lipopolysaccharide (LPS)‑induced activation of AKT by inhibiting its phosphorylation at Thr‑308 and Ser‑473, and reversing LPS‑induced proliferation. These results suggested that the inhibition of AKT activation via targeting of TRAF6 with quinine may be a viable anticancer therapeutic approach and a successful example of the alternative use of the original therapeutic properties of this well‑known natural product.
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Affiliation(s)
- Wenjuan Liu
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
| | - Yonghao Qi
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
| | - Lingyu Liu
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
| | - Yu Tang
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
| | - Jing Wei
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
| | - Lijun Zhou
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
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He Z, Huang C, Lin G, Ye Y. siRNA-induced TRAF6 knockdown promotes the apoptosis and inhibits the invasion of human lung cancer SPC-A1 cells. Oncol Rep 2016; 35:1933-40. [PMID: 26847475 PMCID: PMC4774669 DOI: 10.3892/or.2016.4602] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 01/21/2016] [Indexed: 12/11/2022] Open
Abstract
Tumor necrosis factor receptor-associated factor 6 (TRAF6) has been found to be involved in multiple cancers. However, the effect of small interfering RNA (siRNA)-induced knockdown of TRAF6 on the biological behaviors of cancer cells remains unknown. Thus, the present study aimed to investigate the effect of siRNA-induced knockdown of TRAF6 on the biological behaviors of human lung cancer SPC-A1 cells. The expression of TRAF6 was determined in human lung adenocarcinoma A549, non-small cell lung cancer H1650, human airway epithelial Calu-3 and human lung cancer SPC-A1 cell lines using quantitative RT-PCR (qRT-PCR) and western blotting at the transcriptional and translational levels. TRAF6 expression was knocked down in the SPC-A1 cells using an siRNA technique, and the effects of TRAF6 knockdown on NF-κB activity, cell proliferation, apoptosis, cell cycle, invasion and migration of the SPC-A1 cells were determined using electrophoretic mobility shift assay (EMSA), cell proliferation assay, flow cytometry, Transwell invasion assay and scratch wound assay. In addition, the protein expression of CD24, CXCR4, MMP1, MMP2, MMP9, TWIST, TIMP-2 and Slug was quantified using western blotting assay. Western blotting and qRT-PCR assays showed upregulation of TRAF6 at both the translational and transcriptional levels in the Calu-3 and SPC-A1 cells, and K63-linked ubiquitination of TRAF6 and constitutive NF-κB activation were detected in the SPC-A1 cells. Knockdown of TRAF6 inhibited the migration and invasion and promoted the apoptosis of the SPC-A1 cells, but had little effect on cell proliferation and the cell cycle. In addition, siRNA-induced TRAF6 knockdown caused a marked reduction in the protein expression of CD24 and CXCR4, but had little effect on MMP-1, MMP-2, MMP-9, Twist, TIMP-2 or Slug expression. The present study demonstrated that TRAF6 is upregulated in human lung cancer cells, and siRNA-induced TRAF6 knockdown inhibits the invasion of lung cancer cells and promotes apoptosis. It is suggested that TRAF6 may be a promising target for the therapy of lung cancer.
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Affiliation(s)
- Zhiyong He
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou, Fujian 350014, P.R. China
| | - Chuanzhong Huang
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou, Fujian 350014, P.R. China
| | - Gen Lin
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou, Fujian 350014, P.R. China
| | - Yunbin Ye
- Department of Medical Oncology, Fujian Provincial Cancer Hospital, Fujian Medical University Teaching Hospital, Fuzhou, Fujian 350014, P.R. China
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14
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TRAF6 is required for BLyS-mediated NF-κB signaling in multiple myeloma cells. Med Oncol 2015; 32:239. [DOI: 10.1007/s12032-015-0671-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 07/22/2015] [Indexed: 01/13/2023]
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15
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Zhang XL, Dang YW, Li P, Rong MH, Hou XX, Luo DZ, Chen G. Expression of Tumor Necrosis Factor Receptor-associated Factor 6 in Lung Cancer Tissues. Asian Pac J Cancer Prev 2015; 15:10591-6. [DOI: 10.7314/apjcp.2014.15.24.10591] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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16
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Sun H, Li X, Fan L, Wu G, Li M, Fang J. TRAF6 is upregulated in colon cancer and promotes proliferation of colon cancer cells. Int J Biochem Cell Biol 2014; 53:195-201. [DOI: 10.1016/j.biocel.2014.04.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/04/2014] [Accepted: 04/10/2014] [Indexed: 01/19/2023]
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17
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Feng H, Lopez GY, Kim CK, Alvarez A, Duncan CG, Nishikawa R, Nagane M, Su AJA, Auron PE, Hedberg ML, Wang L, Raizer JJ, Kessler JA, Parsa AT, Gao WQ, Kim SH, Minata M, Nakano I, Grandis JR, McLendon RE, Bigner DD, Lin HK, Furnari FB, Cavenee WK, Hu B, Yan H, Cheng SY. EGFR phosphorylation of DCBLD2 recruits TRAF6 and stimulates AKT-promoted tumorigenesis. J Clin Invest 2014; 124:3741-56. [PMID: 25061874 DOI: 10.1172/jci73093] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 06/06/2014] [Indexed: 12/31/2022] Open
Abstract
Aberrant activation of EGFR in human cancers promotes tumorigenesis through stimulation of AKT signaling. Here, we determined that the discoidina neuropilin-like membrane protein DCBLD2 is upregulated in clinical specimens of glioblastomas and head and neck cancers (HNCs) and is required for EGFR-stimulated tumorigenesis. In multiple cancer cell lines, EGFR activated phosphorylation of tyrosine 750 (Y750) of DCBLD2, which is located within a recently identified binding motif for TNF receptor-associated factor 6 (TRAF6). Consequently, phosphorylation of DCBLD2 Y750 recruited TRAF6, leading to increased TRAF6 E3 ubiquitin ligase activity and subsequent activation of AKT, thereby enhancing EGFR-driven tumorigenesis. Moreover, evaluation of patient samples of gliomas and HNCs revealed an association among EGFR activation, DCBLD2 phosphorylation, and poor prognoses. Together, our findings uncover a pathway in which DCBLD2 functions as a signal relay for oncogenic EGFR signaling to promote tumorigenesis and suggest DCBLD2 and TRAF6 as potential therapeutic targets for human cancers that are associated with EGFR activation.
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Wang Y, Sun C, Li T, Xu H, Zhou Y, Dan H, Jiang L, Zeng X, Li L, Li J, Liao G, Chen Q. Integrative approach detected association between genetic variants of microRNA binding sites of TLRs pathway genes and OSCC susceptibility in Chinese Han population. PLoS One 2014; 9:e101695. [PMID: 24999832 PMCID: PMC4085003 DOI: 10.1371/journal.pone.0101695] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/10/2014] [Indexed: 02/05/2023] Open
Abstract
Oral squamous cell carcinoma (OSCC) is a leading malignancy worldwide; the overall 5-year survival rate is approximately 50%. A variety of proteins in Toll-like receptors (TLRs) pathway have been related with the risk of OSCC. However, the influence of genetic variations in TLRs pathway genes on OSCC susceptibility is unclear. Previous studies mainly focused on the coding region of genes, while the UTR region remains unstudied. In the current study, a bioinformatics approach was performed to select candidate single nucleotide polymorphisms (SNPs) on microRNA binding sites of TLRs pathway genes related with OSCC. After screening 90 OSCC related TLRs pathway genes, 16 SNPs were selected for genotyping. We found that rs5030486, the polymorphisms on 3′ UTR of TRAF6, was significantly associated with OSCC risk. AG genotype of TRAF6 was strongly associated with a decreased risk of OSCC (OR = 0.252; 95% CI = 0.106, 0.598; p = 0.001). In addition, AG genotype was also related with a reduced risk of OSCC progression both in univariable analysis (HR = 0.303, 95% CI = 0.092, 0.995) and multivariable analysis (HR = 0.272, 95% CI = 0.082, 0.903). Furthermore, after detecting the mRNA expression level of TRAF6 in 24 OSCC patients, we found that TRAF6 expression level was significantly different between patients carrying different genotypes at locus rs5030486 (p = 0.013), indicating that rs5030486 of TRAF6 might contribute to OSCC risk by altering TRAF6 expression level. In general, these data indicated that SNP rs5030486 could be a potential bio-marker for OSCC risk and our results might provide new insights into the association of polymorphisms within the non-coding area of genes with cancers.
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Affiliation(s)
- Yun Wang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Chongkui Sun
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Taiwen Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hao Xu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- West China School of Public Health, Sichuan University, Chengdu, China
| | - Yu Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hongxia Dan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lu Jiang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Zeng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Longjiang Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- * E-mail: (GL); (JL)
| | - Ga Liao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- * E-mail: (GL); (JL)
| | - Qianming Chen
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Crebanine, an aporphine alkaloid, sensitizes TNF-α-induced apoptosis and suppressed invasion of human lung adenocarcinoma cells A549 by blocking NF-κB-regulated gene products. Tumour Biol 2014; 35:8615-24. [PMID: 24867094 DOI: 10.1007/s13277-014-1998-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 04/22/2014] [Indexed: 01/01/2023] Open
Abstract
Crebanine is an alkaloid known to exhibit anticancer, but its mechanism is not well understood. Besides, the nuclear factor-kappa B (NF-κB) transcription factor has been correlated with inflammation, carcinogenesis, tumor cell survival, invasion, and angiogenesis. In this study, we investigated the effects of crebanine on tumor necrosis factor alpha (TNF-α)-induced NF-κB activation and the expression of NF-κB-regulated gene products. We found that crebanine reduced the cell proliferation of lung, ovarian, and breast cancer cells. Crebanine also potentiated TNF-α-induced apoptosis which correlated with the suppression of the gene products linked to cell survival, B cell lymphoma-extra large, and proliferation, cyclin D1. In addition, crebanine affected TNF-α-induced activation of caspase-8, caspase-3, and poly(ADP-ribose) polymerase cleavage, indicating that the apoptotic effects of TNF-α were enhanced by crebanine. Moreover, crebanine reduced TNF-α-induced A549 cell invasion and migration. Furthermore, crebanine suppressed the TNF-α-mediated expression of proteins that involved cancer cell invasion (matrix metalloproteinase 9 urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor and intercellular adhesion molecule 1) and angiogenesis (COX-2 and VEGF), all of which are known to be regulated by NF-κB. We also demonstrated that TNF-α induced NF-κB DNA-binding activity, which was inhibited by crebanine. Moreover, crebanine suppressed the TNF-α-induced degradation of inhibitor of NF-κB alpha (IκBa), which led to reduced NF-κB translocation to the nucleus. Taken together, our results demonstrated that crebanine reduced TNF-α-induced cancer cell proliferation, invasion, and survival by suppressing NF-κB activity and expression profile of its downstream genes.
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Zhan Z, Xie X, Cao H, Zhou X, Zhang XD, Fan H, Liu Z. Autophagy facilitates TLR4- and TLR3-triggered migration and invasion of lung cancer cells through the promotion of TRAF6 ubiquitination. Autophagy 2013; 10:257-68. [PMID: 24321786 DOI: 10.4161/auto.27162] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Autophagy contributes to the pathogenesis of cancer, whereas toll-like receptors (TLRs) also play an important role in cancer development and immune escape. However, little is known about the potential interaction between TLR signaling and autophagy in cancer cells. Here we show that autophagy induced by TLR4 or TLR3 activation enhances various cytokine productions through promoting TRAF6 (TNF receptor-associated factor 6, E3 ubiquitin protein ligase) ubiquitination and thus facilitates migration and invasion of lung cancer cells. Stimulation of TLR4 and TLR3 with lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid [poly(I:C)] respectively triggered autophagy in lung cancer cells. This was mediated by the adaptor protein, toll-like receptor adaptor molecule 1 (TICAM1/TRIF), and was required for TLR4- and TLR3-induced increases in the production of IL6, CCL2/MCP-1 [chemokine (C-C motif) ligand 2], CCL20/MIP-3α [chemokine (C-C motif) ligand 20], VEGFA (vascular endothelial growth factor A), and MMP2 [matrix metallopeptidase 2 (gelatinase A, 72 kDa gelatinase, 72 kDa type IV collagenase)]. These cytokines appeared to be necessary for enhanced migration and invasion of lung cancer cells upon TLR activation. Remarkably, inhibition of autophagy by chemical or genetic approaches blocked TLR4- or TLR3-induced Lys63 (K63)-linked ubiquitination of TRAF6 that was essential for activation of MAPK and NFKB (nuclear factor of kappa light polypeptide gene enhancer in B-cells) pathways, both of which were involved in the increased production of the cytokines. Collectively, these results identify induction of autophagy by TLR4 and TLR3 as an important mechanism that drives lung cancer progression, and indicate that inhibition of autophagy may be a useful strategy in the treatment of lung cancer.
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Affiliation(s)
- Zhenzhen Zhan
- Research Center for Translational Medicine & Institute of Heart Failure; East Hospital; Tongji University School of Medicine; Shanghai, China
| | - Xuefeng Xie
- School of Pharmacology; Anhui Medical University; Hefei, Anhui, China
| | - Hao Cao
- Department of Cardiac Surgery; East Hospital; Tongji University School of Medicine; Shanghai, China
| | - Xiaohui Zhou
- Research Center for Translational Medicine & Institute of Heart Failure; East Hospital; Tongji University School of Medicine; Shanghai, China
| | - Xu Dong Zhang
- School of Medicine and Public Health; University of Newcastle; NSW, Australia
| | - Huimin Fan
- Research Center for Translational Medicine & Institute of Heart Failure; East Hospital; Tongji University School of Medicine; Shanghai, China; Department of Cardiac Surgery; East Hospital; Tongji University School of Medicine; Shanghai, China
| | - Zhongmin Liu
- Research Center for Translational Medicine & Institute of Heart Failure; East Hospital; Tongji University School of Medicine; Shanghai, China; Department of Cardiac Surgery; East Hospital; Tongji University School of Medicine; Shanghai, China
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21
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Abstract
The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of intracellular proteins were originally identified as signaling adaptors that bind directly to the cytoplasmic regions of receptors of the TNF-R superfamily. The past decade has witnessed rapid expansion of receptor families identified to employ TRAFs for signaling. These include Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), T cell receptor, IL-1 receptor family, IL-17 receptors, IFN receptors and TGFβ receptors. In addition to their role as adaptor proteins, most TRAFs also act as E3 ubiquitin ligases to activate downstream signaling events. TRAF-dependent signaling pathways typically lead to the activation of nuclear factor-κBs (NF-κBs), mitogen-activated protein kinases (MAPKs), or interferon-regulatory factors (IRFs). Compelling evidence obtained from germ-line and cell-specific TRAF-deficient mice demonstrates that each TRAF plays indispensable and non-redundant physiological roles, regulating innate and adaptive immunity, embryonic development, tissue homeostasis, stress response, and bone metabolism. Notably, mounting evidence implicates TRAFs in the pathogenesis of human diseases such as cancers and autoimmune diseases, which has sparked new appreciation and interest in TRAF research. This review presents an overview of the current knowledge of TRAFs, with an emphasis on recent findings concerning TRAF molecules in signaling and in human diseases.
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Affiliation(s)
- Ping Xie
- Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Nelson Labs Room B336, Piscataway, New Jersey 08854.
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22
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TNF receptor-associated factor 6 regulates proliferation, apoptosis, and invasion of glioma cells. Mol Cell Biochem 2013; 377:87-96. [PMID: 23358926 DOI: 10.1007/s11010-013-1573-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/18/2013] [Indexed: 01/28/2023]
Abstract
Tumor necrosis factor receptor-associated factor 6 (TRAF6), which plays an important role in inflammation and immune response, is an essential adaptor protein for the NF-κB (nuclear factor κB) signaling pathway. Recent studies have shown that TRAF6 played an important role in tumorigenesis and invasion by suppressing NF-κB activation. However, up to now, the biologic role of TRAF6 in glioma has still remained unknown. To address the expression of TRAF6 in glioma cells, four glioma cell lines (U251, U-87MG, LN-18, and U373) and a non-cancerous human glial cell line SVG p12 were used to explore the protein expression of TRAF6 by Western blot. Our results indicated that TRAF6 expression was upregulated in human glioma cell lines, especially in metastatic cell lines. To investigate the role of TRAF6 in cell proliferation, apoptosis, invasion, and migration of glioma, we generated human glioma U-87MG cell lines in which TRAF6 was either overexpressed or depleted. Subsequently, the effects of TRAF6 on cell viability, cell cycle distribution, apoptosis, invasion, and migration in U-87MG cells were determined with 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) assay, flow cytometry analysis, transwell invasion assay, and wound-healing assay. The results showed that knockdown of TRAF6 could decrease cell viability, suppress cell proliferation, invasion and migration, and promote cell apoptosis, whereas overexpression of TRAF6 displayed the opposite effects. In addition, the effects of TRAF6 on the expression of phosphor-NF-κB (p-p65), cyclin D1, caspase 3, and MMP-9 were also probed. Knockdown of TRAF6 could lower the expression of p-p65, cyclin D1, and MMP-9, and raise the expression of caspase 3. All these results suggested that TRAF6 might be involved in the potentiation of growth, proliferation, invasion, and migration of U-87MG cell, as well as inhibition of apoptosis of U-87MG cell by abrogating activation of NF-κB.
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