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Jin J, Wang Y, Hu Y. STAMBPL1, transcriptionally regulated by SREBP1, promotes malignant behaviors of hepatocellular carcinoma cells via Wnt/β-catenin signaling pathway. Mol Carcinog 2024. [PMID: 39150093 DOI: 10.1002/mc.23801] [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: 01/20/2024] [Revised: 07/15/2024] [Accepted: 07/24/2024] [Indexed: 08/17/2024]
Abstract
Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. STAM binding protein-like 1 (STAMBPL1), a key member of the COP9 signalosome subunit 5/serine protease 27/proteasome 26S subunit non-ATPase 7 (JAMM) family, is closely associated with tumor development. In this work, data from GSE101728 and GSE84402 chips were analyzed, and STAMBPL1 was selected as the target factor. This study aimed to reveal the potential function of STAMBPL1 in HCC. Clinical results showed that STAMBPL1 was significantly increased in tumor tissues of HCC patients, and its expression was strongly associated with tumor size and TNM stage. Furthermore, STAMBPL1-overexpressed Hep3B2.1-7 cell line or STAMBPL1-silenced SNU-182 cell line were established using lentivirus carrying cDNA encoding STAMBPL1 mRNA or shRNA targeting STAMBPL1, respectively. STAMBPL1-overexpressed cells exhibited a pronounced enhancement of proliferation in vitro and in vivo. Exogenous expression of STAMBPL1 increased the percentage of cells in the S phase and upregulated the expressions of CyclinD1 and Survivin. As expected, STAMBPL1 knockdown exhibited completely opposite effects, resulting in impaired tumorigenicity in vitro and in vivo. Mechanistically, STAMBPL1 activated Wnt/β-catenin pathway and increased the expression of downstream cancer-promoting genes. Interestingly, we found that STAMBPL1 was transcriptionally regulated by sterol regulatory element-binding protein 1 (SREBP1), a modulator of lipid metabolism, as evidenced by luciferase reporter and chromatin-immunoprecipitation (Ch-IP) assays. Notably, STAMBPL1 overexpression increased lipid accumulation in HCC cells and xenograft tumors. Totally our findings suggest that STAMBPL1 plays a vital role in the tumorigenicity of HCC cells. Modulation of Wnt/β-catenin and lipid metabolism may contribute to its pro-cancer effects. STAMBPL1 may serve as a therapeutic target of HCC.
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Affiliation(s)
- Junyi Jin
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yihui Wang
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yaoyuan Hu
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
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2
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Matsukuma H, Kobayashi Y, Oka S, Higashijima F, Kimura K, Yoshihara E, Sasai N, Shiraishi K. Prominin-1 deletion results in spermatogenic impairment, sperm morphological defects, and infertility in mice. Reprod Med Biol 2023; 22:e12514. [PMID: 37292088 PMCID: PMC10244806 DOI: 10.1002/rmb2.12514] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 03/30/2023] [Accepted: 04/09/2023] [Indexed: 06/10/2023] Open
Abstract
Purpose Spermatogenesis is a complex process orchestrated by several essential genes. Prominin-1 (Prom1/PROM1) is a gene that is expressed in the testis but with a poorly understood role in spermatogenesis. Methods We used Prom1 knockout (Prom1 KO) mice to assess the role of Prom1 in spermatogenesis. To this end, we performed immunohistochemistry, immunofluorescence, western blotting, β-galactosidase staining, and apoptosis assay. Additionally, we analyzed the morphology of sperm and assessed litter sizes. Results We observed that PROM1 is localized to the dividing spermatocytes in seminiferous epithelial cells, sperm, and columnar epithelium in the epididymis. In the Prom1 KO testis, an aberrant increase in apoptotic cells and a decrease in proliferating seminiferous epithelial cells were observed. Cellular FLICE-like inhibitory protein (c-FLIP) and extracellular signal-regulated kinase 1/2 (ERK1/2) expression were also significantly decreased in Prom1 KO testis. In addition, a significantly increased number of epididymal spermatozoa with abnormal morphology and less motility was found in Prom1 KO mice. Conclusions PROM1 maintains spermatogenic cell proliferation and survival via c-FLIP expression in the testis. It is also involved in sperm motility and fertilization potential. The mechanism underlying the effect of Prom1 on sperm morphology and motility remains to be identified.
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Affiliation(s)
- Haruka Matsukuma
- Department of Urology, School of MedicineYamaguchi UniversityUbeJapan
| | - Yuka Kobayashi
- Department of Ophthalmology, School of MedicineYamaguchi UniversityUbeJapan
| | - Shintaro Oka
- Department of Urology, School of MedicineYamaguchi UniversityUbeJapan
| | | | - Kazuhiro Kimura
- Department of Ophthalmology, School of MedicineYamaguchi UniversityUbeJapan
| | - Erika Yoshihara
- Developmental Biomedical Science, Division of Biological SciencesNara Institute of Science and Technology IkomaNaraJapan
| | - Noriaki Sasai
- Developmental Biomedical Science, Division of Biological SciencesNara Institute of Science and Technology IkomaNaraJapan
| | - Koji Shiraishi
- Department of Urology, School of MedicineYamaguchi UniversityUbeJapan
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3
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Wang WD, Shang Y, Wang C, Ni J, Wang AM, Li GJ, Su L, Chen SZ. c-FLIP promotes drug resistance in non-small-cell lung cancer cells via upregulating FoxM1 expression. Acta Pharmacol Sin 2022; 43:2956-2966. [PMID: 35422085 PMCID: PMC9622852 DOI: 10.1038/s41401-022-00905-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/27/2022] [Indexed: 01/27/2023] Open
Abstract
The forkhead box M1 (FoxM1) protein, a transcription factor, plays critical roles in regulating tumor growth and drug resistance, while cellular FLICE-inhibitory protein (c-FLIP), an anti-apoptotic regulator, is involved in the ubiquitin-proteasome pathway. In this study, we investigated the effects of c-FLIP on the expression and ubiquitination levels of FoxM1 along with drug susceptibility in non-small-cell lung cancer (NSCLC) cells. We first showed that the expression levels of FoxM1 and c-FLIP were increased and positively correlated (R2 = 0.1106, P < 0.0001) in 90 NSCLC samples. The survival data from prognostic analysis demonstrated that high expression of c-FLIP and/or FoxM1 was related to poor prognosis in NSCLC patients and that the combination of FoxM1 and c-FLIP could be a more precise prognostic biomarker than either alone. Then, we explored the functions of c-FLIP/FoxM1 in drug resistance in NSCLC cell lines and a xenograft mouse model in vivo. We showed that c-FLIP stabilized FoxM1 by inhibiting its ubiquitination, thus upregulated the expression of FoxM1 at post-transcriptional level. In addition, a positive feedback loop composed of FoxM1, β-catenin and p65 also participated in c-FLIP-FoxM1 axis. We revealed that c-FLIP promoted the resistance of NSCLC cells to thiostrepton and osimertinib by upregulating FoxM1. Taken together, these results reveal a new mechanism by which c-FLIP regulates FoxM1 and the function of this interaction in the development of thiostrepton and osimertinib resistance. This study provides experimental evidence for the potential therapeutic benefit of targeting the c-FLIP-FoxM1 axis for lung cancer treatment.
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Affiliation(s)
- Wen-Die Wang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yue Shang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Chen Wang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Jun Ni
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Ai-Min Wang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Gao-Jie Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Ling Su
- School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Shu-Zhen Chen
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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4
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Liu Z, Li C, Liu M, Song Z, Moyer MP, Su D. The Low-density Lipoprotein Receptor-related Protein 6 Pathway in the Treatment of Intestinal Barrier Dysfunction Induced by Hypoxia and Intestinal Microbiota through the Wnt/β-catenin Pathway. Int J Biol Sci 2022; 18:4469-4481. [PMID: 35864969 PMCID: PMC9295061 DOI: 10.7150/ijbs.72283] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 07/03/2022] [Indexed: 11/12/2022] Open
Abstract
Our study is to explore the key molecular of Low-density lipoprotein receptor-related protein 6 (LRP6) and the related Wnt/β-catenin pathway regulated by LRP6 during the intestinal barrier dysfunction. Colorectal protein profile analysis showed that LRP6 expression was decreased in dextran sulfate sodium (DSS)-induced colitis mice, and mice received fecal bacteria transplantation from stroke patients. Mice with intestinal hypoxia and intestinal epithelial cells cultured in hypoxia showed decreased expression of LRP6. Overexpression of LPR6 or its N-terminus rescued the Wnt/β-catenin signaling pathway which was inhibited by hypoxia and endoplasmic reticulum stress. In mice overexpressing of LRP6, the expression of β-catenin and DKK1 increased, Bcl2 decreased, and Bax increased. Mice with LRP6 knockout showed an opposite trend, and the expression of Claudin2, Occludin and ZO-1 decreased. Two drugs, curcumin and auranofin could alleviate intestinal barrier damage in DSS-induced colitis mice by targeting LRP-6. Therefore, gut microbiota dysbiosis and hypoxia can inhibit the LRP6 and Wnt/β-catenin pathway, and drugs targeting LRP6 can protect the intestinal barrier.
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Affiliation(s)
- Zhihua Liu
- Department of Anorectal Surgery, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510799, China.,Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University
| | - Chao Li
- Department of Anorectal Surgery, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510799, China.,Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University
| | - Min Liu
- Department of Anorectal Surgery, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510799, China.,Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University
| | - Zhen Song
- Department of Anorectal Surgery, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510799, China.,Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University
| | | | - Dan Su
- Department of Anorectal Surgery, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510799, China.,Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University.,INCELL Corporation, San Antonio, Texas, 78249, USA.,Department of Anorectal surgery. The Sixth Affiliated Hospital of Sun Yatsen University, Guangzhou 510665, China
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5
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Smyth P, Sessler T, Scott CJ, Longley DB. FLIP(L): the pseudo-caspase. FEBS J 2020; 287:4246-4260. [PMID: 32096279 PMCID: PMC7586951 DOI: 10.1111/febs.15260] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/10/2020] [Accepted: 02/24/2020] [Indexed: 12/27/2022]
Abstract
Possessing structural homology with their active enzyme counterparts but lacking catalytic activity, pseudoenzymes have been identified for all major enzyme groups. Caspases are a family of cysteine‐dependent aspartate‐directed proteases that play essential roles in regulating cell death and inflammation. Here, we discuss the only human pseudo‐caspase, FLIP(L), a paralog of the apoptosis‐initiating caspases, caspase‐8 and caspase‐10. FLIP(L) has been shown to play a key role in regulating the processing and activity of caspase‐8, thereby modulating apoptotic signaling mediated by death receptors (such as TRAIL‐R1/R2), TNF receptor‐1 (TNFR1), and Toll‐like receptors. In this review, these canonical roles of FLIP(L) are discussed. Additionally, a range of nonclassical pseudoenzyme roles are described, in which FLIP(L) functions independently of caspase‐8. These nonclassical pseudoenzyme functions enable FLIP(L) to play key roles in the regulation of a wide range of biological processes beyond its canonical roles as a modulator of cell death.
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Affiliation(s)
- Peter Smyth
- The Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast, UK
| | - Tamas Sessler
- The Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast, UK
| | - Christopher J Scott
- The Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast, UK
| | - Daniel B Longley
- The Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast, UK
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Safa AR, Kamocki K, Saadatzadeh MR, Bijangi-Vishehsaraei K. c-FLIP, a Novel Biomarker for Cancer Prognosis, Immunosuppression, Alzheimer's Disease, Chronic Obstructive Pulmonary Disease (COPD), and a Rationale Therapeutic Target. BIOMARKERS JOURNAL 2019; 5:4. [PMID: 32352084 PMCID: PMC7189798 DOI: 10.36648/2472-1646.5.1.59] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Dysregulation of c-FLIP (cellular FADD-like IL-1β-converting enzyme inhibitory protein) has been shown in several diseases including cancer, Alzheimer's disease, and chronic obstructive pulmonary disease (COPD). c-FLIP is a critical anti-cell death protein often overexpressed in tumors and hematological malignancies and its increased expression is often associated with a poor prognosis. c-FLIP frequently exists as long (c-FLIPL) and short (c-FLIPS) isoforms, regulates its anti-cell death functions through binding to FADD (FAS associated death domain protein), an adaptor protein known to activate caspases-8 and -10 and links c-FLIP to several cell death regulating complexes including the death-inducing signaling complex (DISC) formed by various death receptors. c-FLIP also plays a critical role in necroptosis and autophagy. Furthermore, c-FLIP is able to activate several pathways involved in cytoprotection, proliferation, and survival of cancer cells through various critical signaling proteins. Additionally, c-FLIP can inhibit cell death induced by several chemotherapeutics, anti-cancer small molecule inhibitors, and ionizing radiation. Moreover, c-FLIP plays major roles in aiding the survival of immunosuppressive tumor-promoting immune cells and functions in inflammation, Alzheimer's disease (AD), and chronic obstructive pulmonary disease (COPD). Therefore, c-FLIP can serve as a versatile biomarker for cancer prognosis, a diagnostic marker for several diseases, and an effective therapeutic target. In this article, we review the functions of c-FLIP as an anti-apoptotic protein and negative prognostic factor in human cancers, and its roles in resistance to anticancer drugs, necroptosis and autophagy, immunosuppression, Alzheimer's disease, and COPD.
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Affiliation(s)
- Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, USA
| | - Krzysztof Kamocki
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, USA
| | - M Reza Saadatzadeh
- Department of Neurosurgery, Indiana University School of Medicine, Indianapolis, USA
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7
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Humphreys L, Espona-Fiedler M, Longley DB. FLIP as a therapeutic target in cancer. FEBS J 2018; 285:4104-4123. [PMID: 29806737 DOI: 10.1111/febs.14523] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/11/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022]
Abstract
One of the classic hallmarks of cancer is disruption of cell death signalling. Inhibition of cell death promotes tumour growth and metastasis, causes resistance to chemo- and radiotherapies as well as targeted agents, and is frequently due to overexpression of antiapoptotic proteins rather than loss of pro-apoptotic effectors. FLIP is a major apoptosis-regulatory protein frequently overexpressed in solid and haematological cancers, in which its high expression is often correlated with poor prognosis. FLIP, which is expressed as long (FLIP(L)) and short (FLIP(S)) splice forms, achieves its cell death regulatory functions by binding to FADD, a critical adaptor protein which links FLIP to the apical caspase in the extrinsic apoptotic pathway, caspase-8, in a number of cell death regulating complexes, such as the death-inducing signalling complexes (DISCs) formed by death receptors. FLIP also plays a key role (together with caspase-8) in regulating another form of cell death termed programmed necrosis or 'necroptosis', as well as in other key cellular processes that impact cell survival, including autophagy. In addition, FLIP impacts activation of the intrinsic mitochondrial-mediated apoptotic pathway by regulating caspase-8-mediated activation of the pro-apoptotic Bcl-2 family member Bid. It has been demonstrated that FLIP can not only inhibit death receptor-mediated apoptosis, but also cell death induced by a range of clinically relevant chemotherapeutic and targeted agents as well as ionizing radiation. More recently, key roles for FLIP in promoting the survival of immunosuppressive tumour-promoting immune cells have been discovered. Thus, FLIP is of significant interest as an anticancer therapeutic target. In this article, we review FLIP's biology and potential ways of targeting this important tumour and immune cell death regulator.
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Affiliation(s)
- Luke Humphreys
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
| | - Margarita Espona-Fiedler
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
| | - Daniel B Longley
- Drug Resistance Group, Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, UK
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8
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Abdul AURM, De Silva B, Gary RK. The GSK3 kinase inhibitor lithium produces unexpected hyperphosphorylation of β-catenin, a GSK3 substrate, in human glioblastoma cells. Biol Open 2018; 7:bio.030874. [PMID: 29212798 PMCID: PMC5829510 DOI: 10.1242/bio.030874] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Lithium salt is a classic glycogen synthase kinase 3 (GSK3) inhibitor. Beryllium is a structurally related inhibitor that is more potent but relatively uncharacterized. This study examined the effects of these inhibitors on the phosphorylation of endogenous GSK3 substrates. In NIH-3T3 cells, both salts caused a decrease in phosphorylated glycogen synthase, as expected. GSK3 inhibitors produce enhanced phosphorylation of Ser9 of GSK3β via a positive feedback mechanism, and both salts elicited this enhancement. Another GSK3 substrate is β-catenin, which has a central role in Wnt signaling. In A172 human glioblastoma cells, lithium treatment caused a surprising increase in phospho-Ser33/Ser37-β-catenin, which was quantified using an antibody-coupled capillary electrophoresis method. The β-catenin hyperphosphorylation was unaffected by p53 RNAi knockdown, indicating that p53 is not involved in the mechanism of this response. Lithium caused a decrease in the abundance of axin, a component of the β-catenin destruction complex that has a role in coordinating β-catenin ubiquitination and protein turnover. The axin and phospho-β-catenin results were reproduced in U251 and U87MG glioblastoma cell lines. These observations run contrary to the conventional view of the canonical Wnt signaling pathway, in which a GSK3 inhibitor would be expected to decrease, not increase, phospho-β-catenin levels. This article has an associated First Person interview with the first author of the paper. Summary: GSK3 inhibitors have potential use against Alzheimer's disease and other conditions. In this study, a classic inhibitor produced unexpected molecular effects on key components of the Wnt signaling pathway.
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Affiliation(s)
| | - Bhagya De Silva
- Department of Chemistry and Biochemistry, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
| | - Ronald K Gary
- Department of Chemistry and Biochemistry, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
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9
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Huang QQ, Birkett R, Doyle RE, Haines GK, Perlman H, Shi B, Homan P, Xing L, Pope RM. Association of Increased F4/80 high Macrophages With Suppression of Serum-Transfer Arthritis in Mice With Reduced FLIP in Myeloid Cells. Arthritis Rheumatol 2017; 69:1762-1771. [PMID: 28511285 DOI: 10.1002/art.40151] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 05/09/2017] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Macrophages are critical in the pathogenesis of rheumatoid arthritis (RA). We recently demonstrated that FLIP is necessary for the differentiation and/or survival of macrophages. We also showed that FLIP is highly expressed in RA synovial macrophages. This study was undertaken to determine if a reduction in FLIP in mouse macrophages reduces synovial tissue macrophages and ameliorates serum-transfer arthritis. METHODS Mice with Flip deleted in myeloid cells (Flipf/f LysMc/+ mice) and littermate controls were used. Arthritis was induced by intraperitoneal injection of K/BxN serum. Disease severity was evaluated by clinical score and change in ankle thickness, and joints were examined by histology and immunohistochemistry. Cells were isolated from the ankles and bone marrow of the mice and examined by flow cytometry, real-time quantitative reverse transcriptase-polymerase chain reaction, or Western blotting. RESULTS In contrast to expectations, Flipf/f LysMc/+ mice developed more severe arthritis early in the clinical course, but peak arthritis was attenuated and the resolution phase more complete than in control mice. Prior to the induction of serum-transfer arthritis, the number of tissue-resident macrophages was reduced. On day 9 after arthritis induction, the number of F4/80high macrophages in the joints of the Flipf/f LysMc/+ mice was not decreased, but increased. FLIP was reduced in the F4/80high macrophages in the ankles of the Flipf/f LysMc/+ mice, while F4/80high macrophages expressed an antiinflammatory phenotype in both the Flipf/f LysMc/+ and control mice. CONCLUSION Our observations suggest that reducing FLIP in macrophages by increasing the number of antiinflammatory macrophages may be an effective therapeutic approach to suppress inflammation, depending on the disease stage.
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Affiliation(s)
- Qi-Quan Huang
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Robert Birkett
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Renee E Doyle
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | | | - Harris Perlman
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Bo Shi
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Philip Homan
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Lianping Xing
- University of Rochester Medical Center, Rochester, New York
| | - Richard M Pope
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
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10
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Zhang J, Jiang HY, Zhang LK, Xu WL, Qiao YT, Zhu XG, Liu W, Zheng QQ, Hua ZC. C-FLIP L Modulated Wnt/β-Catenin Activation via Association with TIP49 Protein. J Biol Chem 2016; 292:2132-2142. [PMID: 28028178 DOI: 10.1074/jbc.m116.753251] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/05/2016] [Indexed: 12/24/2022] Open
Abstract
Cellular FLICE-like inhibitory protein (c-FLIPL) is a key inhibitory protein in the extrinsic apoptotic pathway. Recent studies showed that c-FLIPL could translocate into the nucleus and might be involved in the Wnt signaling pathway. The nuclear function of c-FLIPL was still unclear. Here we found a novel c-FLIPL-associated protein TIP49, which is a nuclear protein identified as a cofactor in the transcriptional regulation of β-catenin. They had co-localization in the nucleus and the DED domain of c-FLIPL was required for the association with TIP49. By performing ChIP experiments, C-FLIPL was detected in the ITF-2 locus and facilitated TIP49 accumulation in the formation of complexes at the T-cell-specific transcription factor site of human ITF-2 promoter. When TIP49 knockdown, c-FLIPL-driven Wnt activation, and cell proliferation were inhibited, suggesting that a role of nuclear c-FLIPL involved in modulation of the Wnt pathway was in a TIP49-dependent manner. Elevated expression of c-FLIPL and TIP49 that coincided in human lung cancers were analyzed in silico using the Oncomine database. Their high expressions were reconfirmed in six lung cancer cell lines and correlated with cell growth. The association of c-FLIPL and TIP49 provided an additional mechanism involved in c-FLIPL-mediated functions, including Wnt activation.
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Affiliation(s)
- Jing Zhang
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and .,the Changzhou High-Tech Research Institute of Nanjing University and Jiangsu Target Pharma Laboratories Inc., Changzhou 213164, Jiangsu, People's Republic of China
| | - Heng-Yi Jiang
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Lin-Kai Zhang
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Wen-Ling Xu
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Yi-Ting Qiao
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Xu-Guo Zhu
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Wan Liu
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Qian-Qian Zheng
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and
| | - Zi-Chun Hua
- From The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, Jiangsu and .,the Changzhou High-Tech Research Institute of Nanjing University and Jiangsu Target Pharma Laboratories Inc., Changzhou 213164, Jiangsu, People's Republic of China
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11
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Tian F, Hu Y, Sun X, Lu G, Li Y, Yang J, Tao J. Suppression of c‑FLIPL promotes JNK activation in malignant melanoma cells. Mol Med Rep 2016; 13:2904-8. [PMID: 26847085 DOI: 10.3892/mmr.2016.4856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 01/11/2016] [Indexed: 11/05/2022] Open
Abstract
The up‑regulation of cellular Fas‑associated death domain‑like interleukin‑1β‑converting enzyme (FLICE)‑like inhibitory protein (c‑FLIP) has been reported in various tumor types, and has been previously shown to be associated with the clinicopathological features of melanoma. To assess its potential role in cancer therapy, the present study evaluated the effects of short hairpin (sh)RNAs of different c‑FLIP isoforms on cellular proliferation and c‑Jun N‑terminal kinase (JNK) signaling. Human c‑FLIP shRNA plasmids were constructed and transfected into the A875 melanoma cell line. It was observed that c‑FLIP shRNA exhibited strong inhibitory effects against the levels of phosphorylated‑JNK and inhibited cellular proliferation in A875 cells. Thus, this indicated that c‑FLIP long form shRNA serves a specific inhibitory role in cellular proliferation through inducing the activation of the JNK pathway in A875 cells. The present study provided insight into the development of RNAi based therapies for melanoma.
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Affiliation(s)
- Fen Tian
- Department of Dermatology, Sixth People's Hospital of Zhengzhou, Zhengzhou, Henan 450015, P.R. China
| | - Yange Hu
- Department of Dermatology, Sixth People's Hospital of Zhengzhou, Zhengzhou, Henan 450015, P.R. China
| | - Xixi Sun
- Department of Dermatology, Sixth People's Hospital of Zhengzhou, Zhengzhou, Henan 450015, P.R. China
| | - Gaihui Lu
- Department of Dermatology, Sixth People's Hospital of Zhengzhou, Zhengzhou, Henan 450015, P.R. China
| | - Yan Li
- Department of Dermatology, Affiliated Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Jing Yang
- Department of Dermatology, Affiliated Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Juan Tao
- Department of Dermatology, Affiliated Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
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French R, Hayward O, Jones S, Yang W, Clarkson R. Cytoplasmic levels of cFLIP determine a broad susceptibility of breast cancer stem/progenitor-like cells to TRAIL. Mol Cancer 2015; 14:209. [PMID: 26667821 PMCID: PMC4678708 DOI: 10.1186/s12943-015-0478-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 12/03/2015] [Indexed: 01/05/2023] Open
Abstract
Background The clinical application of TRAIL receptor agonists as a novel cancer therapy has been tempered by heterogeneity in tumour responses. This is illustrated in breast cancer, where TRAIL is cytotoxic in cell lines of mesenchymal origin but refractory in lines with an epithelial-like phenotype. However, it is now evident that intra-tumour heterogeneity includes a minority subpopulation of tumour-initiating stem/progenitor-like cells (CSCs) that possess mesenchymal characteristics. We hypothesised therefore that TRAIL may target these phenotypically distinct CSC-like cells that are common to most - if not all - breast cancers, thus impacting on the source of malignancy in a much broader range of breast tumour subtypes than previously envisaged. Methods We used colony formation, tumoursphere, flow cytometry and xenograft tumour initiation assays to observe the TRAIL sensitivity of CSC-like cells in a panel of two mesenchymal-like (TRAIL-sensitive) and four epithelial-like (TRAIL-resistant) breast cancer cell lines. Subcellular levels of the endogenous TRAIL inhibitor, cFLIP, were determined by western blot and immunofluorescence microscopy. The effect of the subcellular redistribution of cFLIP on TRAIL sensitivity and Wnt signalling was determined using cFLIP localisation mutants and the TOPFlash reporter assay respectively. Results TRAIL universally suppressed the clonal expansion of stem/progenitors in all six of the breast cancer cell lines tested, irrespective of their phenotype or overall sensitivity to TRAIL. A concomitant reduction in tumour initiation was confirmed in the TRAIL-resistant epithelial cell line, MCF-7, following serial dilution xenotransplantation. Furthermore TRAIL sensitivity of breast CSCs was inversely proportional to the relative cytoplasmic levels of cFLIP while overexpression of cFLIP in the cytosol using subcellular localization mutants of cFLIP protected these cells from cytotoxicity. The accumulation of nuclear cFLIP on the other hand did not influence TRAIL cytotoxicity but instead promoted Wnt-dependent signalling. Conclusion These data propose a novel role for TRAIL as a selective CSC agent with a broad specificity for both epithelial and mesenchymal breast tumour subtypes. Furthermore we identify a dual role for cFLIP in the maintenance of breast CSC viability, dependent upon its subcellular distribution. Electronic supplementary material The online version of this article (doi:10.1186/s12943-015-0478-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rhiannon French
- European Cancer Stem Cell Research Institute Cardiff University School of Biosciences, Haydn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Olivia Hayward
- European Cancer Stem Cell Research Institute Cardiff University School of Biosciences, Haydn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Samuel Jones
- European Cancer Stem Cell Research Institute Cardiff University School of Biosciences, Haydn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - William Yang
- European Cancer Stem Cell Research Institute Cardiff University School of Biosciences, Haydn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Richard Clarkson
- European Cancer Stem Cell Research Institute Cardiff University School of Biosciences, Haydn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
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Sakamaki K, Iwabe N, Iwata H, Imai K, Takagi C, Chiba K, Shukunami C, Tomii K, Ueno N. Conservation of structure and function in vertebrate c-FLIP proteins despite rapid evolutionary change. Biochem Biophys Rep 2015; 3:175-189. [PMID: 29124180 PMCID: PMC5668880 DOI: 10.1016/j.bbrep.2015.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 08/05/2015] [Accepted: 08/05/2015] [Indexed: 12/26/2022] Open
Abstract
Cellular FLICE-like inhibitory protein (c-FLIP, gene symbol CFLAR) was first identified as a negative regulator of death receptor-mediated apoptosis in mammals. To understand the ubiquity and diversity of the c-FLIP protein subfamily during evolution, c-FLIP orthologs were identified from a comprehensive range of vertebrates, including birds, amphibians, and fish, and were characterized by combining experimental and computational analysis. Predictions of three-dimensional protein structures and molecular phylogenetic analysis indicated that the conserved structural features of c-FLIP proteins are all derived from an ancestral caspase-8, although they rapidly diverged from the subfamily consisting of caspases-8, -10, and -18. The functional role of the c-FLIP subfamily members is nearly ubiquitous throughout vertebrates. Exogenous expression of non-mammalian c-FLIP proteins in cultured mammalian cells suppressed death receptor-mediated apoptosis, implying that all of these proteins possess anti-apoptotic activity. Furthermore, non-mammalian c-FLIP proteins induced NF-κB activation much like their mammalian counterparts. The CFLAR mRNAs were synthesized during frog and fish embryogenesis. Overexpression of a truncated mutant of c-FLIP in the Xenopus laevis embryos by mRNA microinjection caused thorax edema and abnormal constriction of the abdomen. Depletion of cflar transcripts in zebrafish resulted in developmental abnormalities accompanied by edema and irregular red blood cell flow. Thus, our results demonstrate that c-FLIP/CFLAR is conserved in both protein structure and function in several vertebrate species, and suggest a significant role of c-FLIP in embryonic development.
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Key Words
- Apoptosis
- CARD, caspase-recruitment domain
- CASc, Caspase, interleukin-1 β converting enzyme homologs
- CHX, cycloheximide
- Caspase-8
- DED, death effector domain
- EGFP, enhanced green fluorescent protein
- Embryogenesis
- Evolution
- FADD, Fas-associated death domain protein
- MO, morpholino oligonucleotide
- NF-κB
- NF-κB, Nuclear factor-kappa B
- ODC, ornithine decarboxylase
- PCR, polymerase chain reaction
- Pseudocatalytic triad
- RT-PCR, reverse transcription-polymerase chain reaction
- TRAF2, tumor necrosis factor receptor-associated factor 2
- c-FLIP, cellular FLICE-like inhibitory protein
- tubα6, tubulin α6
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Affiliation(s)
- Kazuhiro Sakamaki
- Department of Animal Development and Physiology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Naoyuki Iwabe
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Hiroaki Iwata
- Multi-scale Research Center for Medical Science, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Kenichiro Imai
- Biotechnology Research Institute for Drug Discovery, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Chiyo Takagi
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Kumiko Chiba
- Department of Animal Development and Physiology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Chisa Shukunami
- Department of Cellular Differentiation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Kentaro Tomii
- Biotechnology Research Institute for Drug Discovery, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Naoto Ueno
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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Abstract
Cellular FLICE-inhibitory protein (cFLIP) is structurally related to caspase-8, but lacks its protease activity. Cflip gene encodes several splicing variants including short form (cFLIPs) and long form (cFLIPL). cFLIPL is composed of two death effector domains at the N terminus and a C-terminal caspase-like domain, and cFLIPs lacks the caspase-like domain. Our studies reveal that cFLIP plays a central role in NF-κB-dependent survival signals that control apoptosis and programmed necrosis. Germline deletion of Cflip results in embryonic lethality due to enhanced apoptosis and programmed necrosis; however, the combined deletion of the death-signaling regulators, Fadd and Ripk3, prevents embryonic lethality in Cflip-deficient mice. Moreover, tissue-specific deletion of Cflip reveals cFLIP as a crucial regulator that maintains tissue homeostasis of immune cells, hepatocytes, intestinal epithelial cells, and epidermal cells by preventing apoptosis and programmed necrosis.
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Novell A, Martínez-Alonso M, Mira M, Tarragona J, Salud A, Matias-Guiu X. Prognostic value of c-FLIPL/s, HIF-1α, and NF-κβ in stage II and III rectal cancer. Virchows Arch 2014; 464:645-54. [DOI: 10.1007/s00428-014-1572-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 02/21/2014] [Accepted: 03/13/2014] [Indexed: 12/12/2022]
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Kikuchi R, Ohata H, Ohoka N, Kawabata A, Naito M. APOLLON protein promotes early mitotic CYCLIN A degradation independent of the spindle assembly checkpoint. J Biol Chem 2013; 289:3457-67. [PMID: 24302728 DOI: 10.1074/jbc.m113.514430] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the mammalian cell cycle, both CYCLIN A and CYCLIN B are required for entry into mitosis, and their elimination is also essential to complete the process. During mitosis, CYCLIN A and CYCLIN B are ubiquitylated by the anaphase-promoting complex/cyclosome (APC/C) and then subjected to proteasomal degradation. However, CYCLIN A, but not CYCLIN B, begins to be degraded in the prometaphase when APC/C is inactivated by the spindle assembly checkpoint (SAC). Here, we show that APOLLON (also known as BRUCE or BIRC6) plays a role in SAC-independent degradation of CYCLIN A in early mitosis. APPOLON interacts with CYCLIN A that is not associated with cyclin-dependent kinases. APPOLON also interacts with APC/C, and it facilitates CYCLIN A ubiquitylation. In APPOLON-deficient cells, mitotic degradation of CYCLIN A is delayed, and the total, but not the cyclin-dependent kinase-bound, CYCLIN A level was increased. We propose APPOLON to be a novel regulator of mitotic CYCLIN A degradation independent of SAC.
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Affiliation(s)
- Ryo Kikuchi
- From the Institute of Molecular and Cellular Biosciences
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17
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Abstract
Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIP(L)), short (c-FLIP(S)), and c-FLIP(R) splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIP(L) and c-FLIP(S) are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP(L) in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP(L) and c-FLIP(S) splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function.
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18
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Abstract
Cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (c-FLIP) is a major antiapoptotic protein and an important cytokine and chemotherapy resistance factor that suppresses cytokine- and chemotherapy-induced apoptosis. c-FLIP is expressed as long (c-FLIPL), short (c-FLIPS), and c-FLIPR splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 and TRAIL receptor 5 (DR5). This interaction in turn prevents Death-Inducing Signaling Complex (DISC) formation and subsequent activation of the caspase cascade. c-FLIPL and c-FLIPS are also known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective and pro-survival signaling proteins including Akt, ERK, and NF-κB. In addition to its role in apoptosis, c-FLIP is involved in programmed necroptosis (necrosis) and autophagy. Necroptosis is regulated by the Ripoptosome, which is a signaling intracellular cell death platform complex. The Ripoptosome contains receptor-interacting protein-1/Receptor-Interacting Protein-3 (RIP1), caspase-8, caspase-10, FADD, and c-FLIP isoforms involved in switching apoptotic and necroptotic cell death. c-FLIP regulates the Ripoptosome; in addition to its role in apoptosis, it is therefore also involved in necrosis. c-FLIPL attenuates autophagy by direct acting on the autophagy machinery by competing with Atg3 binding to LC3, thereby decreasing LC3 processing and inhibiting autophagosome formation. Upregulation of c-FLIP has been found in various tumor types, and its silencing has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. This review focuses on (1) the anti-apoptotic role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and chemotherapy drug resistance, as well as its roles in necrosis and autophagy, and (2) modulation of c-FLIP expression as a means to enhance apoptosis and modulate necrosis and autophagy in cancer cells.
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Affiliation(s)
- Ahmad R Safa
- Department of Pharmacology & Toxicology, Indiana University School of Medicine, IN 46202, USA ; Indiana University Simon Cancer Center, Indiana University School of Medicine, IN 46202, USA
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19
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Safa AR. c-FLIP, a master anti-apoptotic regulator. Exp Oncol 2012; 34:176-184. [PMID: 23070002 PMCID: PMC4817998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (c-FLIP) is a master anti-apoptotic regulator and resistance factor that suppresses tumor necrosis factor-α (TNF-α), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, as well as apoptosis triggered by chemotherapy agents in malignant cells. c-FLIP is expressed as long (c-FLIP(L)), short (c-FLIP(S)), and c-FLIP(R) splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 and TRAIL receptor 5 (DR5) in a ligand-dependent and -independent fashion and forms an apoptosis inhibitory complex (AIC). This interaction in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. c-FLIP(L) and c-FLIP(S) are also known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective and pro-survival signaling proteins including Akt, ERK, and NF-kB. Upregulation of c-FLIP has been found in various tumor types, and its silencing has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP(L) in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP(L) and c-FLIP(S) splice variants have been found, and much effort is focused on developing other c-FLIP-targeted cancer therapies. This review focuses on (1) the anti-apoptotic role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and chemotherapy drug resistance, (2) the molecular mechanisms and factors that regulate c-FLIP expression, and (3) modulation of c-FLIP expression and function to eliminate cancer cells or increase the efficacy of anticancer agents. This article is part of a Special Issue entitled "Apoptosis: Four Decades Later".
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Affiliation(s)
- A R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Schattenberg JM, Schuchmann M, Galle PR. Cell death and hepatocarcinogenesis: Dysregulation of apoptosis signaling pathways. J Gastroenterol Hepatol 2011; 26 Suppl 1:213-9. [PMID: 21199533 DOI: 10.1111/j.1440-1746.2010.06582.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hepatocellular carcinoma (HCC) remains a disease with a poor prognosis despite recent advances in the pathophysiology and treatment. Although the disease is biologically heterogeneous, dysregulation of cellular proliferation and apoptosis both occur frequently and contribute to the malignant phenotype. Chronic liver disease is associated with intrahepatic inflammation which promotes dysregulation of cellular signaling pathways; this triggers proliferation and thus lays the ground for expansion of premalignant cells. Cancer emerges when immunological control fails and transformed cells develop resistance against cell death signaling pathways. The same mechanisms underlie the poor responsiveness of HCC towards chemotherapy. Only recently advances in understanding the signaling pathways involved has led to the development of an effective pharmacological therapy for advanced disease. The current review will discuss apoptosis signaling pathways and focus on apoptosis resistance of HCC involving derangements in cell death receptors (e.g. tumor necrosis factor-alpha [TNF], CD95/Apo-1, TNF-related apoptosis-inducing ligand [TRAIL]) and associated adapter molecules (e.g. FADD and FLIP) of apoptotic signaling pathways. In addition, the role of the transcription factor nuclear factor-kappaB (NFκB) and members of the B cell leukemia-2 (Bcl-2) family that contribute to the regulation of apoptosis in hepatocytes are discussed. Eventually, the delineation of cell death signaling pathways could contribute to the implementation of new therapeutic strategies to treat HCC.
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Affiliation(s)
- Jorn Markus Schattenberg
- Department of Medicine, University Medical Center, Johannes Gutenberg University Mainz, Germany.
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21
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Kim S, Ohoka N, Okuhira K, Sai K, Nishimaki-Mogami T, Naito M. Modulation of RIP1 ubiquitylation and distribution by MeBS to sensitize cancer cells to tumor necrosis factor α-induced apoptosis. Cancer Sci 2010; 101:2425-9. [PMID: 20825417 PMCID: PMC11158959 DOI: 10.1111/j.1349-7006.2010.01697.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Overexpression of anti-apoptosis protein cIAP1 due to its genetic amplification is found in certain cancers such as esophageal squamous cell carcinoma, hepatocellular carcinoma, cervical cancer and lung cancer, and plays a significant role in resistance to cancer therapy. We previously reported that a class of small molecules represented by (-)-N-[(2S, 3R)-3-amino-2-hydroxy-4-phenyl-butyryl]-L-leucine methyl ester (MeBS) activates auto-ubiquitylation of cIAP1 for proteasomal degradation, and enhances apoptosis of various cancer cells. However, the molecular mechanism of how MeBS sensitizes cancer cells to apoptosis via downregulation of cIAP1 is not well understood. Here, we show that ubiquitylation and distribution of RIP1, a protein ubiquitylated by cIAP1, is modulated by MeBS. Upon tumor necrosis factor (TNF)α stimulation, ubiquitylated RIP1 associates with the TNF-receptor (TNFR) complex, whereas non-ubiquitylated RIP1 associates with caspase8. MeBS reduces the ubiquitylated RIP1 in the TNFR complex and increases non-ubiquitylated RIP1 bound to caspase8. Downregulation of RIP1 by siRNA reduces apoptosis induced by TNFα plus MeBS treatment. These results indicate an important role of RIP1 in apoptosis induced by combined treatment with TNFα and MeBS, suggesting that MeBS sensitizes cancer cells to apoptosis by modulating RIP1 ubiquitylation and distribution.
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Affiliation(s)
- Seungseob Kim
- National Institute of Health Sciences, Tokyo Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
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22
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Yerbes R, Palacios C, Reginato MJ, López-Rivas A. Cellular FLIP(L) plays a survival role and regulates morphogenesis in breast epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:168-78. [PMID: 20951169 DOI: 10.1016/j.bbamcr.2010.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 10/04/2010] [Accepted: 10/05/2010] [Indexed: 10/19/2022]
Abstract
Strong evidences support the inhibitory activity of cellular FLICE-inhibitory protein (FLIP) in the apoptotic signalling by death receptors in tumor cells. However, little is known about the role of FLIP in the regulation of apoptosis in non-transformed cells. In this report, we demonstrate that FLIP(L) plays an important role as a survival protein in non-transformed breast epithelial cells. Silencing of FLIP(L) by siRNA methodology enhances TRAIL-R2 expression and activates a caspase-dependent cell death process in breast epithelial cells. This cell death requires the expression of TRAIL, TRAIL-R2, FADD and procaspase-8 proteins. A mitochondria-operated apoptotic pathway is partially required for FLIP(L) siRNA-induced apoptosis. Interestingly, FLIP(L) silencing markedly abrogates formation of acinus-like structures in a three-dimensional basement membrane culture model (3D) of the human mammary MCF-10A cell line through a caspase-8 dependent process. Furthermore, over-expression of FLIP(L) in MCF-10A cells delayed lumen formation in 3D cultures. Our results highlight the central role of FLIP in maintaining breast epithelial cell viability and suggest that the mechanisms regulating FLIP levels should be finely controlled to prevent unwanted cell demise.
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Affiliation(s)
- Rosario Yerbes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa, Consejo Superior de Investigaciones Cientificas, Sevilla, Spain
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Abstract
FLIP is a well-established suppressor of death receptor-mediated apoptosis. To define its essential in vivo role in myeloid cells, we generated and characterized mice with Flip conditionally deleted in the myeloid lineage. Myeloid specific Flip-deficient mice exhibited growth retardation, premature death, and splenomegaly with altered architecture and extramedullary hematopoiesis. They also displayed a dramatic increase of circulating neutrophils and multiorgan neutrophil infiltration. In contrast, although circulating inflammatory monocytes were also significantly increased, macrophages in the spleen, lymph nodes, and the peritoneal cavity were reduced. In ex vivo cultures, bone marrow progenitor cells failed to differentiate into macrophages when Flip was deleted. Mixed bone marrow chimera experiments using cells from Flip-deficient and wild-type mice did not demonstrate an inflammatory phenotype. These observations demonstrate that FLIP is necessary for macrophage differentiation and the homeostatic regulation of granulopoiesis.
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Tiwary R, Yu W, Li J, Park SK, Sanders BG, Kline K. Role of endoplasmic reticulum stress in alpha-TEA mediated TRAIL/DR5 death receptor dependent apoptosis. PLoS One 2010; 5:e11865. [PMID: 20686688 PMCID: PMC2912340 DOI: 10.1371/journal.pone.0011865] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 07/07/2010] [Indexed: 11/19/2022] Open
Abstract
Background α-TEA (RRR-α-tocopherol ether-linked acetic acid analog), a derivative of RRR-α-tocopherol (vitamin E) exhibits anticancer actions in vitro and in vivo in variety of cancer types. The objective of this study was to obtain additional insights into the mechanisms involved in α-TEA induced apoptosis in human breast cancer cells. Methodology/Principal Findings α-TEA induces endoplasmic reticulum (ER) stress as indicated by increased expression of CCAAT/enhancer binding protein homologous protein (CHOP) as well as by enhanced expression or activation of specific markers of ER stress such as glucose regulated protein (GRP78), phosphorylated alpha subunit of eukaryotic initiation factor 2 (peIF-2α), and spliced XBP-1 mRNA. Knockdown studies using siRNAs to TRAIL, DR5, JNK and CHOP as well as chemical inhibitors of ER stress and caspase-8 showed that: i) α-TEA activation of DR5/caspase-8 induces an ER stress mediated JNK/CHOP/DR5 positive amplification loop; ii) α-TEA downregulation of c-FLIP (L) protein levels is mediated by JNK/CHOP/DR5 loop via a JNK dependent Itch E3 ligase ubiquitination that further serves to enhance the JNK/CHOP/DR5 amplification loop by preventing c-FLIP's inhibition of caspase-8; and (iii) α-TEA downregulation of Bcl-2 is mediated by the ER stress dependent JNK/CHOP/DR5 signaling. Conclusion Taken together, ER stress plays an important role in α-TEA induced apoptosis by enhancing DR5/caspase-8 pro-apoptotic signaling and suppressing anti-apoptotic factors c-FLIP and Bcl-2 via ER stress mediated JNK/CHOP/DR5/caspase-8 signaling.
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Affiliation(s)
- Richa Tiwary
- School of Biological Sciences/C0900, University of Texas at Austin, Austin, Texas, United States of America
| | - Weiping Yu
- School of Biological Sciences/C0900, University of Texas at Austin, Austin, Texas, United States of America
| | - Jing Li
- School of Biological Sciences/C0900, University of Texas at Austin, Austin, Texas, United States of America
| | - Sook-Kyung Park
- School of Biological Sciences/C0900, University of Texas at Austin, Austin, Texas, United States of America
| | - Bob G. Sanders
- School of Biological Sciences/C0900, University of Texas at Austin, Austin, Texas, United States of America
| | - Kimberly Kline
- Department of Nutritional Sciences/A2703, University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Bijangi-Vishehsaraei K, Huang S, Safa AR, Saadatzadeh MR, Murphy MP. 4-(4-Chloro-2-methylphenoxy)-N-hydroxybutanamide (CMH) targets mRNA of the c-FLIP variants and induces apoptosis in MCF-7 human breast cancer cells. Mol Cell Biochem 2010; 342:133-142. [PMID: 20446019 DOI: 10.1007/s11010-010-0477-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 04/17/2010] [Indexed: 12/30/2022]
Abstract
Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor for the tumor necrosis factor-related apoptosis-inducing ligand TRAIL and in drug resistance in human malignancies. c-FLIP is an antagonist of caspases-8 and -10, which inhibits apoptosis and is expressed as long (c-FLIP(L)) and short (c-FLIP(S)) splice forms. c-FLIP is often overexpressed in various human cancers, including breast cancer. Several studies have shown that silencing c-FLIP by specific siRNAs sensitizes cancer cells to TRAIL and anticancer agents. However, systemic use of siRNA as a therapeutic agent is not practical at present. In order to reduce or inhibit c-FLIP expression, small molecules are needed to allow targeting c-FLIP without inhibiting caspases-8 and -10. We used a small molecule inhibitor of c-FLIP, 4-(4-chloro-2-methylphenoxy)-N-hydroxybutanamide (CMH), and show that CMH, but not its inactive analog, downregulated c-FLIP(L) and c-FLIP(S) mRNA and protein levels, caused poly(ADP-ribose) polymerase (PARP) degradation, reduced cell survival, and induced apoptosis in MCF-7 breast cancer cells. These results revealed that c-FLIP is a critical apoptosis regulator that can serve as a target for small molecule inhibitors that downregulate its expression and serve as effective targeted therapeutics against breast cancer cells.
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Affiliation(s)
- Khadijeh Bijangi-Vishehsaraei
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202, USA
| | - Su Huang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202, USA
| | - Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202, USA
| | | | - Michael P Murphy
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Downregulation of Epidermal Growth Factor Receptor Expression Contributes to alpha-TEA's Proapoptotic Effects in Human Ovarian Cancer Cell Lines. JOURNAL OF ONCOLOGY 2010; 2010:824571. [PMID: 20224651 PMCID: PMC2833311 DOI: 10.1155/2010/824571] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 12/03/2009] [Indexed: 12/12/2022]
Abstract
RRR-α-tocopherol derivative α-TEA (RRR-α-tocopherol ether-linked acetic acid analog) has been shown to be a potent antitumor agent both in vivo and in vitro. In this study, we investigated the effects of α-TEA on the expression of epidermal growth factor receptor (EGFR) family members, ErbB1, 2 and 3, and the role of ErbB 2 and 3 in α-TEA-induced apoptosis and suppression of Akt, FLIP and survivin in the cisplatin-sensitive (A2780S) and -resistant (A2780/CP70R) human ovarian cancer cell lines. Data show that α-TEA's ability to induced apoptosis was associated with reduced expression of ErbB1 (cisplatin-resistant cells), 2 and 3 (both cell types) and reduced levels of the phosphorylated (active) form of Akt; as well as, reduced levels of FLIP and survivin proteins in both cell types. Ectopic overexpression and siRNA knockdown studies showed that ErbB2, ErbB3, Akt, FLIP and survivin are involved in α-TEA-induce apoptosis and that α-TEA downregulates FLIP and survivin via suppression of pAkt, which is mediated by ErbB2 and ErB3. Thus, α-TEA is a potent pro-apoptotic agent for both cisplatin-sensitive and -resistant ovarian cancer cell lines in cell culture and it produces cell death, at least in part, by downregulation of members of the EGFR family.
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Katayama R, Ishioka T, Takada S, Takada R, Fujita N, Tsuruo T, Naito M. Modulation of Wnt signaling by the nuclear localization of cellular FLIP-L. J Cell Sci 2010; 123:23-8. [PMID: 20016063 DOI: 10.1242/jcs.058602] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Cellular FLIP (cFLIP) inhibits the apoptosis signaling initiated by death receptor ligation. We previously reported that a long form of cFLIP (cFLIP-L) enhances Wnt signaling via inhibition of beta-catenin ubiquitylation. In this report, we present evidence that cFLIP-L translocates into the nucleus, which could have a role in modulation of Wnt signaling. cFLIP-L has a functional bipartite nuclear localization signal (NLS) at the C-terminus. Wild-type cFLIP-L (wt-FLIP-L) localizes in both the nucleus and cytoplasm, whereas NLS-mutated cFLIP-L localizes predominantly in the cytoplasm. cFLIP-L also has a nuclear export signal (NES) near the NLS, and leptomycin B, an inhibitor of CRM1-dependent nuclear export, increases the nuclear accumulation of cFLIP-L, suggesting that it shuttles between the nucleus and cytoplasm. Expression of mutant cFLIP-L proteins with a deletion or mutations in the NLS and NES confers resistance to Fas-mediated apoptosis, as does wt-FLIP-L, but they do not enhance Wnt signaling, which suggests an important role of the C-terminus of cFLIP-L in Wnt-signaling modulation. When wt-FLIP-L is expressed in the cytoplasm by conjugation with exogenous NES (NES-FLIP-L), Wnt signaling is not enhanced, whereas the NES-FLIP-L increases cytoplasmic beta-catenin as efficiently as wt-FLIP-L. cFLIP-L physically interacts with the reporter plasmid for Wnt signaling, but not with the control plasmid. These results suggest a role for nuclear cFLIP-L in the modulation of Wnt signaling.
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Affiliation(s)
- Ryohei Katayama
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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Abstract
Death effector domains (DEDs) are protein interaction modules found in a number of proteins known to regulate apoptosis from death receptors. The core DED family members that orchestrate programmed cell death from death receptors include the adaptor protein FADD, the initiator caspases procaspases-8 and -10 and the regulatory protein c-FLIP. Through homotypic DED interactions, these proteins assemble into the death-inducing signaling complex (DISC) to regulate initiator caspase activation and launch the apoptotic proteolytic cascade. A considerable body of evidence, however, is revealing that the same core group of DED-containing proteins also paradoxically promotes survival and proliferation in lymphocytes and possibly other cell types. This review delves into recent findings regarding these two opposing functional aspects of the core DED proteins. We discuss the current effort expanding our structural and biochemical view of how DED proteins assemble into the DISC to fully activate initiator caspases and execute cell death, and finally we examine details linking the same proteins to proliferation and describe how this outcome might be achieved through restricted activation of initiator caspases.
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Affiliation(s)
- J W Yu
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ, 08544 USA.
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Day TW, Huang S, Safa AR. c-FLIP knockdown induces ligand-independent DR5-, FADD-, caspase-8-, and caspase-9-dependent apoptosis in breast cancer cells. Biochem Pharmacol 2008; 76:1694-704. [PMID: 18840411 DOI: 10.1016/j.bcp.2008.09.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 09/02/2008] [Accepted: 09/05/2008] [Indexed: 11/18/2022]
Abstract
Cellular-FLICE inhibitory protein (c-FLIP) is an inhibitor of apoptosis downstream of the death receptors Fas, DR4, and DR5, and is expressed as long (c-FLIP(L)) and short (c-FLIP(S)) splice forms. We found that the knockdown of c-FLIP using small interfering RNA (siRNA) triggered ligand-independent caspase-8- and -9-dependent spontaneous apoptosis and decreased the proliferation of MCF-7 breast cancer cells. Further analysis revealed that an apoptotic inhibitory complex (AIC) comprised of DR5, FADD, caspase-8, and c-FLIP(L) exists in MCF-7 cells, and the absence of c-FLIP(L) from this complex induces DR5- and FADD-mediated caspase-8 activation in the death inducing signaling complex (DISC). c-FLIP(S) was not detected in the AIC, and using splice form-specific siRNAs we showed that c-FLIP(L) but not c-FLIP(S) is required to prevent spontaneous death signaling in MCF-7 cells. These results clearly show that c-FLIP(L) prevents ligand-independent death signaling and provides direct support for studying c-FLIP as a relevant therapeutic target for breast cancers.
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Affiliation(s)
- Travis W Day
- Department of Pharmacology and Toxicology, Indiana University Simon Cancer Center, Indiana University School of Medicine, 1044 West Walnut Street R4-119, Indianapolis, IN 46202, USA
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Leverkus M, Diessenbacher P, Geserick P. FLIP ing the coin? Death receptor-mediated signals during skin tumorigenesis. Exp Dermatol 2008; 17:614-22. [PMID: 18558995 DOI: 10.1111/j.1600-0625.2008.00728.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Keratinocyte skin cancer is a multi-step process, during which a number of obstacles have to be overcome by the tumor cell to allow the development of a manifest tumor. Beside proliferation and immortality, apoptosis resistance is one additional and critical step during skin carcinogenesis. Over the past two decades, much has been learned about the prototypical membrane-bound inducers of apoptosis, namely the death receptors and their ligands, and the apoptosis signalling pathways activated by death receptors have been elucidated in great detail. In contrast, much less is known about the tissue-specific role of the death receptor/ligands systems during the development of skin cancer. Here, we summarize and discuss the role of this intriguing receptor family and the potential mechanistical impact of the intracellular caspase-8 inhibitor cFLIP for keratinocyte skin cancer. Given more recent data about cFLIP and its isoforms, a more complex regulatory role of cFLIP can be suspected. Indeed, cFLIP may not solely interfere with death receptor-mediated apoptosis signalling pathways, but may positively or negatively influence other, potential harmful signalling pathways such as the production of inflammatory cytokines, tumor cell migration or the activation of transcription factors such as NF-kappaB, considered crucial during skin tumorigenesis. In this respect, cFLIP may act to 'FLIP the coin' during the development of keratinocyte skin cancer.
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Affiliation(s)
- Martin Leverkus
- Department of Dermatology and Venerology, Laboratory for Experimental Dermatology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.
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Abstract
Beta-catenin can be cleaved by caspase-3 or degraded by activated glycogen synthase kinase-3beta via phosphorylating beta-catenin. We tested the hypothesis that beta-catenin undergoes degradation after stroke, and its degradation is dependent on caspase activity. Stroke was generated by permanent middle cerebral artery occlusion and 1 h of transient bilateral common carotid artery occlusion in rats. Active caspase-3 was expressed in the ischemic cortex from 5 to 48 h after stroke, whereas beta-catenin markedly degraded at 24 and 48 h after stroke. The caspase 3-specific inhibitor, Z-DQMD-FMK, attenuated beta-catenin degradation, but it did not affect phosphorylation of both beta-catenin and glycogen synthase kinase-3beta. In conclusion, beta-catenin degraded after stroke, and its degradation was caspase-3 dependent.
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Safa AR, Day TW, Wu CH. Cellular FLICE-like inhibitory protein (C-FLIP): a novel target for cancer therapy. Curr Cancer Drug Targets 2008; 8:37-46. [PMID: 18288942 DOI: 10.2174/156800908783497087] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cellular FLICE-like inhibitory protein (c-FLIP) has been identified as a protease-dead, procaspase-8-like regulator of death ligand-induced apoptosis, based on observations that c-FLIP impedes tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by binding to FADD and/or caspase-8 or -10 in a ligand-dependent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. c-FLIP is a family of alternatively spliced variants, and primarily exists as long (c-FLIP(L)) and short (c-FLIP(S)) splice variants in human cells. Although c-FLIP has apoptogenic activity in some cell contexts, which is currently attributed to heterodimerization with caspase-8 at the DISC, accumulating evidence indicates an anti-apoptotic role for c-FLIP in various types of human cancers. For example, small interfering RNAs (siRNAs) that specifically knocked down expression of c-FLIP(L) in diverse human cancer cell lines, e.g., lung and cervical cancer cells, augmented TRAIL-induced DISC recruitment, and thereby enhanced effector caspase stimulation and apoptosis. Therefore, the outlook for the therapeutic index of c-FLIP-targeted drugs appears excellent, not only from the efficacy observed in experimental models of cancer therapy, but also because the current understanding of dual c-FLIP action in normal tissues supports the notion that c-FLIP-targeted cancer therapy will be well tolerated. Interestingly, Taxol, TRAIL, as well as several classes of small molecules induce c-FLIP downregulation in neoplastic cells. Efforts are underway to develop small-molecule drugs that induce c-FLIP downregulation and other c-FLIP-targeted cancer therapies. In this review, we assess the outlook for improving cancer therapy through c-FLIP-targeted therapeutics.
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Affiliation(s)
- Ahmad R Safa
- Department of Pharmacology and Toxicology, Indiana University Cancer Center, Indiana University School of Medicine, 1044 W. Walnut St., Indianapolis, IN 46202, USA.
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Geserick P, Drewniok C, Hupe M, Haas TL, Diessenbacher P, Sprick MR, Schön MP, Henkler F, Gollnick H, Walczak H, Leverkus M. Suppression of cFLIP is sufficient to sensitize human melanoma cells to TRAIL- and CD95L-mediated apoptosis. Oncogene 2007; 27:3211-20. [PMID: 18084329 DOI: 10.1038/sj.onc.1210985] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Death ligands such as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and certain forms of CD95L are attractive therapeutic options for metastatic melanoma. Since knowledge about the regulation of death receptor sensitivity in melanoma is sparse, we have analysed these signaling pathways in detail. The loss of CD95 or TRAIL-R1, but not of TRAIL-R2, surface expression correlated with apoptosis sensitivity in a panel of melanoma cell lines. In contrast, the expression of proteins of the apical apoptosis signaling cascade (FADD, initiator caspases-8 and cFLIP) did not predict apoptosis sensitivity. Since both TRAIL-R1 and -R2 transmit apoptotic signals, we asked whether cFLIP, highly expressed in several of the cell lines tested, is sufficient to maintain resistance to TRAIL-R2-mediated apoptosis. Downregulation of cFLIP in TRAIL-R2-positive, TRAIL-resistant IGR cells dramatically increased TRAIL sensitivity. Conversely ectopic expression of cFLIP in TRAIL-sensitive, TRAIL-R2-expressing RPM-EP melanoma cells inhibited TRAIL- and CD95L-mediated cell death. Thus, modulation of cFLIP is sufficient to sensitize TRAIL-R2-expressing cells for TRAIL. Taken together, albeit expressing all proteins necessary for death receptor-mediated apoptosis, TRAIL-R1 negative melanoma cells cannot undergo TRAIL- or CD95L-induced apoptosis due to expression of cFLIP. Hence, cFLIP represents an attractive therapeutic target for melanoma treatment, especially in combination with TRAIL receptor agonists.
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Affiliation(s)
- P Geserick
- Department of Dermatology and Venereology, Laboratory for Experimental Dermatology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
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Ishioka T, Katayama R, Kikuchi R, Nishimoto M, Takada S, Takada R, Matsuzawa SI, Reed JC, Tsuruo T, Naito M. Impairment of the ubiquitin-proteasome system by cellular FLIP. Genes Cells 2007; 12:735-44. [PMID: 17573774 DOI: 10.1111/j.1365-2443.2007.01087.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cellular FLIP (cFLIP) is a homologue of caspase-8 without protease activity that inhibits the apoptosis signaling initiated by death receptor ligation. We previously reported that a long form of cFLIP (cFLIP-L) inhibits ubiquitylation of beta-catenin and enhances Wnt signaling. Here we show that cFLIP-L impairs the function of the ubiquitin-proteasome system (UPS), and increases the accumulation of various short-lived proteins, such as GFP conjugated with destabilization sequence, beta-catenin and HIF1 alpha, that are subjected to rapid ubiquitylation and degradation by proteasomes. Accordingly, beta-catenin- and HIF1 alpha-mediated gene expressions are induced in the cFLIP-L-expressing cells. Exogenously expressed cFLIP-L accumulates in aggregates at the peri-nuclear region in the cells, and the cFLIP-L aggregates are refractory to solubilization. Like exogenously expressed cFLIP-L, the endogenous cFLIP in A549 lung cancer cells displays particulate distribution in the cells and more than 60% of cFLIP-L is refractory to solubilization. Down-regulation of cFLIP in A549 cells by RNA-mediated interference reduced beta-catenin- and HIF1 alpha-mediated gene expression. These results suggest that cFLIP-L is prone to aggregate and impairs UPS function, which could be involved in the pathological function of cFLIP-L expressed in certain cancer cells.
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Affiliation(s)
- Toshiyasu Ishioka
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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Nakajima A, Komazawa-Sakon S, Takekawa M, Sasazuki T, Yeh WC, Yagita H, Okumura K, Nakano H. An antiapoptotic protein, c-FLIPL, directly binds to MKK7 and inhibits the JNK pathway. EMBO J 2006; 25:5549-59. [PMID: 17110930 PMCID: PMC1679768 DOI: 10.1038/sj.emboj.7601423] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Accepted: 10/04/2006] [Indexed: 01/28/2023] Open
Abstract
Inhibition of NF-kappaB activation increases susceptibility to tumor necrosis factor (TNF)alpha-induced cell death, concurrent with caspases and prolonged c-Jun N-terminal kinase (JNK) activation, and reactive oxygen species (ROS) accumulation. However, the detailed mechanisms are unclear. Here we show that cellular FLICE-inhibitory protein (c-FLIP) is rapidly lost in NF-kappaB activation-deficient, but not wild-type fibroblasts upon TNFalpha stimulation, indicating that NF-kappaB normally maintains the cellular levels of c-FLIP. The ectopic expression of the long form of c-FLIP (c-FLIPL) inhibits TNFalpha-induced prolonged JNK activation and ROS accumulation in NF-kappaB activation-deficient fibroblasts. Conversely, TNFalpha induces prolonged JNK activation and ROS accumulation in c-Flip-/- fibroblasts. Moreover, c-FLIPL directly interacts with a JNK activator, MAP kinase kinase (MKK)7, in a TNFalpha-dependent manner and inhibits the interactions of MKK7 with MAP/ERK kinase kinase 1, apoptosis-signal-regulating kinase 1, and TGFbeta-activated kinase 1. This stimuli-dependent interaction of c-FLIPL with MKK7 might selectively suppress the prolonged phase of JNK activation. Taken that ROS promote JNK activation and activation of the JNK pathway may promote ROS accumulation, c-FLIPL might block this positive feedback loop, thereby suppressing ROS accumulation.
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Affiliation(s)
- Akihito Nakajima
- Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan
| | | | - Mutsuhiro Takekawa
- Division of Molecular Cell Signaling, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Tomonari Sasazuki
- Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan
| | - Wen-Chen Yeh
- Campbell Family Institute for Breast Cancer Research, University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Hideo Yagita
- Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan
| | - Ko Okumura
- Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan
| | - Hiroyasu Nakano
- Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan
- Department of Immunology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. Tel.: +81 3 5802 1045; Fax: +81 3 3813 0421; E-mail:
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Huerta S, Goulet EJ, Livingston EH. Colon cancer and apoptosis. Am J Surg 2006; 191:517-26. [PMID: 16531147 DOI: 10.1016/j.amjsurg.2005.11.009] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 02/06/2023]
Abstract
BACKGROUND The implementation of new therapeutic options for the management of metastatic colon cancer mandates a revisit to apoptosis and its role in colon cancer tumorigenesis with an emphasis on the mechanisms leading to chemotherapeutic resistance and immune system evasion of colon cancer cells. DATA SOURCES Literature regarding molecular apoptosis mechanisms and the role of apoptosis in colon cancer progression are reviewed by this article. CONCLUSION Programmed cell death has rapidly emerged as a potential target for cancer treatment at various stages of tumor progression. Chemoprevention, immuno-regulation, and metastasis are prospective targets by which apoptotic mechanisms could be utilized in the prevention and management of tumorigenesis. Understanding how defects in the death receptor pathway of apoptosis permit colon cancer cells to escape the immune system would allow for treatment options whereby the body's immune system could again recognize and eliminate unwanted cells.
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Affiliation(s)
- Sergio Huerta
- Department of Gastrointestinal and Endocrine Surgery, University of Texas Southwestern Medical Center/Veterans Administration North Texas Health Care System, Dallas, TX 75216, USA.
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Abstract
Cellular caspase-8 (FLICE)-like inhibitory protein (cFLIP) was originally identified as an inhibitor of death-receptor signalling through competition with caspase-8 for recruitment to FAS-associated via death domain (FADD). More recently, it has been determined that both cFLIP and caspase-8 are required for the survival and proliferation of T cells following T-cell-receptor stimulation. This paradoxical finding launched new investigations of how these molecules might connect with signalling pathways that link to cell survival and growth following antigen-receptor activation. As discussed in this Review, insight gained from these studies indicates that cFLIP and caspase-8 form a heterodimer that ultimately links T-cell-receptor signalling to activation of nuclear factor-kappaB through a complex that includes B-cell lymphoma 10 (BCL-10), mucosa-associated-lymphoid-tissue lymphoma-translocation gene 1 (MALT1) and receptor-interacting protein 1 (RIP1).
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Affiliation(s)
- Ralph C Budd
- Immunobiology Program, Department of Medicine, The University of Vermont College of Medicine, Burlington, Vermont 50405, USA
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Shimada K, Nakamura M, Matsuyoshi S, Ishida E, Konishi N. Specific positive and negative effects of FLIP on cell survival in human prostate cancer. Carcinogenesis 2006; 27:1349-57. [PMID: 16537561 DOI: 10.1093/carcin/bgi380] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We demonstrate here for the first time novel positive and negative effects of the FLICE-like inhibitory protein (FLIP) on human prostate cancer cell survival. A proteaosome inhibitor, MG132, mediated cell cycle arrest at G2/M and apoptosis through p38 activation. Interestingly, FLIP was stabilized by MG132 and interacted with Raf-1, resulting in enhancement of p38 signals and cytotoxicity. In contrast, overexpression of FLIP inhibited ubiquitylation and proteasomal degradation of beta-catenin, resulting in increase of the target gene cyclin D1, colony formation and invasive activity. Immunohistochemical analysis and in vitro experiments in primary culture showed FLIP to be overexpressed, statistically associated with expression of beta-catenin/cyclin D1 in metastatic cells, the FLIP/beta-catenin/cyclin D1 signals contributing to colony formation and invasion, which were canceled by FLIP knock down. In contrast, MG132-induced cytotoxicity including apoptosis was strongly inhibited by reduction of FLIP. Taken together, the results indicate that FLIP plays an important role in development of metastatic prostate cancer by inhibiting proteasomal degradation of beta-catenin, whereas it is mainly involved in proteasome inhibitior-mediated cell cycle arrest and apoptosis through activating the Raf-1/p38 pathway. Furthermore, proteasome inhibitors may be effective drugs for advanced prostate cancers overexpressing FLIP.
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Affiliation(s)
- Keiji Shimada
- Department of Pathology, Nara Medical University School of Medicine, Nara, 634-8521, Japan
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Nakagiri S, Murakami A, Takada S, Akiyama T, Yonehara S. Viral FLIP enhances Wnt signaling downstream of stabilized beta-catenin, leading to control of cell growth. Mol Cell Biol 2005; 25:9249-58. [PMID: 16227577 PMCID: PMC1265812 DOI: 10.1128/mcb.25.21.9249-9258.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Death receptor-mediated apoptosis is potently inhibited by viral FLIP (FLICE/caspase 8 inhibitory protein), which is composed of two tandemly repeated death effector domains (DEDs), through reduced activation of procaspase 8. Here, we show that equine herpesvirus 2-encoded viral FLIP E8 enhances Wnt/beta-catenin signaling in a variety of cell lines. E8 was shown to strikingly augment Wnt3a signaling, as shown both in a luciferase assay for T-cell factor/beta-catenin and through induction of endogenous cyclin D1. The effect of E8 was independent of its direct binding activity with DED-containing signaling molecules, including caspase 8 and FADD, in death receptor-mediated apoptosis. E8 enhanced Wnt signaling downstream of stabilized beta-catenin, while a long form of cellular FLIP (c-FLIP(L)) enhanced stabilization of beta-catenin in 293T cells. Consequently, coexpression of E8 and c-FLIP(L) synergistically increased Wnt signaling in 293T cells. Moreover, E8-mediated stimulation of Wnt signaling induced dramatic growth retardation in untransformed cell lines but not in transformed cell lines. Thus, viral FLIP E8 not only inhibits death receptor-mediated apoptosis but also enhances Wnt signaling pathways that are closely related to those of both ontogenesis and oncogenesis.
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Affiliation(s)
- Shiho Nakagiri
- Graduate School of Biostudies, Kyoto University, SCRB/Building G, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Van Geelen CMM, de Vries EGE, de Jong S. Lessons from TRAIL-resistance mechanisms in colorectal cancer cells: paving the road to patient-tailored therapy. Drug Resist Updat 2005; 7:345-58. [PMID: 15790545 DOI: 10.1016/j.drup.2004.11.002] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 11/02/2004] [Accepted: 11/03/2004] [Indexed: 02/06/2023]
Abstract
Colorectal cancer is one of the leading causes of cancer-related deaths worldwide. Intrinsic, as well as acquired, resistance to chemotherapy remains a major problem in the treatment of this disease. It is, therefore, of great importance to develop new, patient-tailored, treatment strategies for colorectal cancer patients. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) acts through the pro-apoptotic DR4 and DR5 receptors in tumor cells without harming normal cells and will soon be tested in clinical trials as a novel anti-cancer agent. However, not all human colon cancer cell lines are sensitive to TRAIL due to intrinsic or acquired TRAIL-resistance. This review discusses the mechanisms and modulation of TRAIL-resistance in colon cancer cells. Cell sensitivity to TRAIL can be affected by TRAIL-receptor expression at the cell membrane, DR4/DR5 ratio and functionality of TRAIL-receptors. Additional intracellular factors leading to TRAIL-resistance affect the caspase 8/c-FLIP ratio, such as loss of caspase 8 and caspase 10 due to mutations or gene methylation, CARP-dependent degradation of active caspase 8 and changes in caspase 8 or c-FLIP expression levels. Further downstream in the TRAIL apoptotic pathway, Bax mutations, or increased expression of IAP family members, in particularly XIAP and survivin, also cause resistance. Chemotherapeutic drugs, NSAIDs, interferon-gamma and proteasome inhibitors can overcome TRAIL-resistance by acting on TRAIL-receptor expression or changing the expression of pro- or anti-apoptotic proteins.
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Affiliation(s)
- Caroline M M Van Geelen
- Department of Medical Oncology, University Hospital of Groningen, PO Box 30.001, 9700 RB Groningen, Groningen, The Netherlands
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