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De Sutter L, Wozniak A, Verreet J, Vanleeuw U, De Cock L, Linde N, Drechsler C, Esdar C, Sciot R, Schöffski P. Antitumor Efficacy of the Novel KIT Inhibitor IDRX-42 (Formerly M4205) in Patient- and Cell Line-Derived Xenograft Models of Gastrointestinal Stromal Tumor (GIST). Clin Cancer Res 2023; 29:2859-2868. [PMID: 37223931 DOI: 10.1158/1078-0432.ccr-22-3822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/17/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023]
Abstract
PURPOSE The majority of gastrointestinal stromal tumors (GIST) are driven by constitutively activated KIT/PDGFRA kinases and are susceptible to treatment with tyrosine kinase inhibitors. During treatment, most of these tumors will develop secondary mutations in KIT or PDGFRA inducing drug resistance, so there is an unmet need for novel therapies. We tested the efficacy of IDRX-42, a novel selective KIT inhibitor with high activity toward the most relevant KIT mutations, in 4 GIST xenograft models. EXPERIMENTAL DESIGN NMRI nu/nu mice were transplanted with patient-derived GIST xenograft models UZLX-GIST9 (KIT:p.P577del;W557LfsX5;D820G), UZLX-GIST2B (KIT:p.A502_Y503dup), UZLX-GIST25 (KIT:p.K642E), and the cell line-derived model GIST882 (KIT:p.K642E). Mice were treated daily with vehicle (control), imatinib (100 mg/kg), sunitinib (20 mg/kg), avapritinib (5 mg/kg), or IDRX-42 (10 mg/kg, 25 mg/kg). Efficacy was assessed by tumor volume evolution, histopathology, grading of histologic response, and IHC. The Kruskal-Wallis and Wilcoxon matched-pairs tests were used for statistical analysis, with P < 0.05 considered as significant. RESULTS IDRX-42 (25 mg/kg) caused tumor volume shrinkage in UZLX-GIST25, GIST882, and UZLX-GIST2B, with a relative decrease to 45.6%, 57.3%, and 35.1% on the last day as compared with baseline, and tumor growth delay (160.9%) compared with control in UZLX-GIST9. Compared with controls, IDRX-42 (25 mg/kg) induced a significant decrease in mitosis. In UZLX-GIST25 and GIST882 grade 2-4 histologic response with myxoid degeneration was observed in all IDRX-42 (25 mg/kg)-treated tumors. CONCLUSIONS IDRX-42 showed significant antitumor activity in patient- and cell line-derived GIST xenograft models. The novel kinase inhibitor induced volumetric responses, decreased mitotic activity, and had antiproliferative effects. In models with KIT exon 13 mutation IDRX-42 induced characteristic myxoid degeneration.
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Affiliation(s)
- Luna De Sutter
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Agnieszka Wozniak
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Jasper Verreet
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Ulla Vanleeuw
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Lore De Cock
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Nina Linde
- The healthcare business of Merck KGaA, Darmstadt, Germany
| | | | | | - Raf Sciot
- Department of Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium
| | - Patrick Schöffski
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven Cancer Institute, Leuven, Belgium
- Department of General Medical Oncology, University Hospitals Leuven, Leuven Cancer Institute, Leuven, Belgium
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Ni B, Li Q, Zhuang C, Huang P, Xia X, Yang L, Ma X, Huang C, Zhao W, Tu L, Shen Y, Zhu C, Zhang Z, Zhao E, Wang M, Cao H. The nerve-tumour regulatory axis GDNF-GFRA1 promotes tumour dormancy, imatinib resistance and local recurrence of gastrointestinal stromal tumours by achieving autophagic flux. Cancer Lett 2022; 535:215639. [PMID: 35288241 DOI: 10.1016/j.canlet.2022.215639] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/01/2022] [Accepted: 03/09/2022] [Indexed: 11/17/2022]
Abstract
Complete surgical resection, accessible therapeutic targets and effective tyrosine kinase inhibitors (TKIs) have not completely cured gastrointestinal stromal tumours (GISTs), with most patients suffering from residual tumours and recurrence. The existence of nerve infiltration in GIST provides a way for tumour cells to escape local resection and systemic targeted therapy, which may challenge the previous understanding of its behaviour patterns and inspire the development of more radical excision and more precise targeted therapy. Moreover, tumour dormancy has emerged as a major cause of drug resistance and tumour relapse. Among these pathways, the nerve-tumour regulatory axis GDNF-GFRA1 is activated in GISTs, assists tumour cells in achieving dormancy and protects them from apoptosis under environmental stress by enhancing autophagic flux. The concrete mechanism is that the GDNF-regulating interaction between GFRA1 and the lysosomal calcium channel MCOLN1 activates Ca2+-dependent TFEB signalling. Activated TFEB transcriptionally regulates intracellular lysosome levels, which could achieve feedback upregulation of cellular autophagy flux during TKI treatment. This dormancy-transition axis fills parts of the mechanistic vacancy before the onset of secondary mutations, and strategies for TKIs combined with targeting GFRA1-dependent autophagy have distinct promise as prospective clinical therapies.
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Affiliation(s)
- Bo Ni
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qing Li
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chun Zhuang
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peiqi Huang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiang Xia
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Linxi Yang
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xinli Ma
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Huang
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenyi Zhao
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lin Tu
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanying Shen
- Department of Pathology, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chunchao Zhu
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zizhen Zhang
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Enhao Zhao
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Ming Wang
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Hui Cao
- Department of Gastrointestinal Surgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Therapeutic Potential of PI3K/AKT/mTOR Pathway in Gastrointestinal Stromal Tumors: Rationale and Progress. Cancers (Basel) 2020; 12:cancers12102972. [PMID: 33066449 PMCID: PMC7602170 DOI: 10.3390/cancers12102972] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 10/03/2020] [Accepted: 10/12/2020] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Most gastrointestinal stromal tumors (GISTs) arise due to gain-of-function mutations of KIT and PDGFRA, encoding the receptor tyrosine kinase (RTK). The introduction of the RTK inhibitor imatinib has significantly improved the management of GISTs; however, drug resistance remains a challenge. Constitutive autophosphorylation of RTKs is associated with the activation of the PI3K/AKT/mTOR pathway. Especially, this pathway plays a pivotal role in mRNA translation initiation, directly regulated by eukaryotic initiation factors (eIFs). This review highlights the progress for targeting PI3K/AKT/mTOR-dependent mechanisms in GISTs and explores the relationship between mTOR downstream eIFs and the development of GISTs, which may be a promising future therapeutic target for this tumor entity. Abstract Gastrointestinal stromal tumor (GIST) originates from interstitial cells of Cajal (ICCs) in the myenteric plexus of the gastrointestinal tract. Most GISTs arise due to mutations of KIT and PDGFRA gene activation, encoding the receptor tyrosine kinase (RTK). The clinical use of the RTK inhibitor imatinib has significantly improved the management of GIST patients; however, imatinib resistance remains a challenge. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is a critical survival pathway for cell proliferation, apoptosis, autophagy and translation in neoplasms. Constitutive autophosphorylation of RTKs has an impact on the activation of the PI3K/AKT/mTOR pathway. In several preclinical and early-stage clinical trials PI3K/AKT/mTOR signaling inhibition has been considered as a promising targeted therapy strategy for GISTs. Various inhibitory drugs targeting different parts of the PI3K/AKT/mTOR pathway are currently being investigated in phase Ι and phase ΙΙ clinical trials. This review highlights the progress for PI3K/AKT/mTOR-dependent mechanisms in GISTs, and explores the relationship between mTOR downstream signals, in particular, eukaryotic initiation factors (eIFs) and the development of GISTs, which may be instrumental for identifying novel therapeutic targets.
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Molecular mechanisms of interplay between autophagy and metabolism in cancer. Life Sci 2020; 259:118184. [PMID: 32763290 DOI: 10.1016/j.lfs.2020.118184] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/26/2020] [Accepted: 07/28/2020] [Indexed: 12/19/2022]
Abstract
Autophagy is an essential mechanism of cellular degradation, a way to protect the cells under stress conditions, such as deprivation of nutrients, growth factors and cellular damage. However, in normal physiology autophagy plays a significant role in cancer cells. Current research is in progress to understand how autophagy and cancer cells go hand in hand to support cancer cell progression. The important aspect in cancer and autophagy is the interdependence of autophagy in the survival and progression of cancer cells. Autophagy is known to be a major cause of chemotherapeutic resistance in various cancer cell types. Therefore, inhibition of autophagy as an effective therapeutic approach is being actively studied and tested in clinical studies. Multiple metabolic pathways are linked with autophagy that could potentially be a significant target for chemotherapeutic strategy. The comprehension of the interconnection of autophagy with cancer metabolism can pave a novel findings for effective combinatorial therapeutic strategies.
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Zheng S, Shu Y, Lu Y, Sun Y. Chloroquine Combined with Imatinib Overcomes Imatinib Resistance in Gastrointestinal Stromal Tumors by Inhibiting Autophagy via the MAPK/ERK Pathway. Onco Targets Ther 2020; 13:6433-6441. [PMID: 32753885 PMCID: PMC7342409 DOI: 10.2147/ott.s256935] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/05/2020] [Indexed: 01/07/2023] Open
Abstract
Background Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. However, up to 40–50% of GISTs develop secondary resistance after an average of 24 months of imatinib treatment. It has been reported that autophagy can promote the survival of GIST cells and induce drug resistance. Presently, the specific mechanism of autophagy in GISTs with imatinib resistance is not clear. Materials and Methods The cell-counting kit (CCK)-8 method and flow cytometry were used for in vitro drug sensitivity testing and autophagy level detection. Detection of the apoptosis level was by flow cytometry with the annexin V Kit. Western blotting was used to analyze the role of autophagy and apoptosis in GIST cells with CQ alone, imatinib alone, or in combination, and to analyze MAPK pathway expression. In vitro results were confirmed by in vivo experiments using the mice model. Hematoxylin and eosin and immunohistochemical staining were used to detect the pathological characteristics and immunophenotype of the transplanted tumor. Detection of KIT and PDGFRA gene mutations in the transplanted imatinib-resistant GIST was done by denaturing high performance liquid chromatography (DHPLC) and direct sequencing. ERK and KIT expression and regulation levels were detected by Western blotting. Results In vitro and vivo experiments, the autophagy level of imatinib-resistant cells was higher than that of normal cells; CQ combined with imatinib can promote apoptosis by blocking autophagy of imatinib-resistant cells. In the meanwhile, we found that the phosphorylation level of ERK may be related to autophagy. Conclusion Our data suggest that autophagy through the MAPK/ERK pathway may play a pivotal role in imatinib-resistant GIST proliferation. Moreover, combining an autophagy inhibitor with imatinib may be a potential valuable strategy in overcoming acquired resistance in GIST patients.
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Affiliation(s)
- Song Zheng
- Department of Medical Oncology, Key Laboratory of Clinical Cancer Pharmacology and Toxicology Research of Zhejiang Province, Zhejiang University School of Medicine Affiliated Hangzhou First People's Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Medical Oncology, Hangzhou Cancer Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Medical Oncology, Zhejiang Chinese Medical University Affiliated Hangzhou First Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Medical Oncology, Nanjing Medical University Affiliated Hangzhou First People's Hospital, Hangzhou, Zhejiang, People's Republic of China
| | - Yefei Shu
- Department of Medical Oncology, Hangzhou Cancer Hospital, Hangzhou, Zhejiang, People's Republic of China
| | - Yidan Lu
- Department of Medical Oncology, Hangzhou Cancer Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Medical Oncology, Zhejiang Chinese Medical University Affiliated Hangzhou First Hospital, Hangzhou, Zhejiang, People's Republic of China
| | - Yangcheng Sun
- Department of Medical Oncology, Hangzhou Cancer Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Medical Oncology, Nanjing Medical University Affiliated Hangzhou First People's Hospital, Hangzhou, Zhejiang, People's Republic of China
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6
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Abstract
Imatinib has revolutionized the treatment of GIST since this drug is able to inhibit tumoral growth by blocking the activity of receptor tyrosine kinases, KIT or PDGFRA, that in these tumors are constitutively activated because of the presence of mutations that alters their catalytic activity. However, despite this enormous improvement in the RFS and OS and in the quality of life of GIST patients, imatinib is not able to eradicate the disease: recurrences occur and acquired resistance is a common event which develops during targeted treatments. Several mechanisms have been demonstrated to be responsible for tumoral growth reactivation which is due to the reactivation of the altered KIT/PDGFRA receptors, no more blocked by the drug. Secondary point mutations are generally observed in the regrowing tumors, and it has been demonstrated that they alter the architectural structure of the site in which the interaction between the drug and the receptor happens. Other mechanisms causing drug resistance have been investigated, indicating that many aspects need to be still explicated and fully understood in order to define a strategy able to fight definitively GIST growth.
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Gebreyohannes YK, Burton EA, Wozniak A, Matusow B, Habets G, Wellens J, Cornillie J, Lin J, Nespi M, Wu G, Zhang C, Bollag G, Debiec-Rychter M, Sciot R, Schöffski P. PLX9486 shows anti-tumor efficacy in patient-derived, tyrosine kinase inhibitor-resistant KIT-mutant xenograft models of gastrointestinal stromal tumors. Clin Exp Med 2018; 19:201-210. [DOI: 10.1007/s10238-018-0541-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/26/2018] [Indexed: 11/25/2022]
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8
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Dagrada G, Rupel K, Zacchigna S, Tamborini E, Pilotti S, Cavalleri A, Fechner LE, Laurini E, Smith DK, Brich S, Pricl S. Self-Assembled Nanomicelles as Curcumin Drug Delivery Vehicles: Impact on Solitary Fibrous Tumor Cell Protein Expression and Viability. Mol Pharm 2018; 15:4689-4701. [DOI: 10.1021/acs.molpharmaceut.8b00655] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Gianpaolo Dagrada
- Laboratory of Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Katia Rupel
- Division of Oral Medicine and Pathology, Dental and Maxillofacial Surgery Clinic, Ospedale Maggiore, Piazza dell’Ospitale 1, 34129 Trieste, Italy
- Department of Medical, Surgical and Health Sciences, University of Trieste, Strada di Fiume 447, 34149 Trieste, Italy
| | - Serena Zacchigna
- Department of Medical, Surgical and Health Sciences, University of Trieste, Strada di Fiume 447, 34149 Trieste, Italy
| | - Elena Tamborini
- Laboratory of Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Silvana Pilotti
- Laboratory of Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Adalberto Cavalleri
- Endocrinology Laboratory, Epidemiology and Prevention Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Loryn E. Fechner
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Erik Laurini
- Molecular Biology and Nanotechnology Laboratory (MolBNL@Units), DEA, University of Trieste, 34127 Trieste, Italy
| | - David K. Smith
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Silvia Brich
- Laboratory of Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy
| | - Sabrina Pricl
- Molecular Biology and Nanotechnology Laboratory (MolBNL@Units), DEA, University of Trieste, 34127 Trieste, Italy
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Spagnuolo RD, Brich S, Bozzi F, Conca E, Castelli C, Tazzari M, Maestro R, Brenca M, Gualeni AV, Gloghini A, Stacchiotti S, Pierotti MA, Pilotti S, Negri T. Sunitinib-induced morpho-functional changes and drug effectiveness in malignant solitary fibrous tumours. Oncotarget 2018; 7:45015-45026. [PMID: 27304187 PMCID: PMC5216702 DOI: 10.18632/oncotarget.7523] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/22/2016] [Indexed: 12/25/2022] Open
Abstract
Sunitinib improves the outcomes of patients with solitary fibrous tumours (SFTs). The aim of this study was to investigate and contextualise sunitinib-induced morpho-functional changes in order to gain insights into the drug's mechanism of action.To this end, four surgical specimens obtained from two sunitinib-responsive patients with malignant SFT, and one primary cell culture obtained from fresh tumoral tissue and its stabilised cell line, were studied by means of immunohistochemistry, bright field in situ hybridisation, immunofluorescence/confocal microscopy, and biochemistry.The post-sunitinib surgical samples were characterised by two biologically relevant morpho-functional changes: clear areas and necrotic foci. The first were associated with the attenuation/loss of PDGFRB expression and decreased mTOR signalling, and corresponded to a pathological response. The second were associated with the over-expression of PDGFRB and VEGFA, strong mTOR signalling activation, and the appearance of HIF1α expression, hallmarks of pathological progression. The analysis clearly showed that sunitinib reduces the vascular supply network and inhibits tumoral cells. It also either induces autophagy, thus favouring drug response, or impairs autophagy as a result of lysosome sequestration, thus favouring disease progression. These distinct autophagic events were associated with different myeloid immune contextures. Finally, we also found that PDGFRB is one of the components of a complex that includes Beclin 1 and VPS34.The results of these tissue-based analyses provide new insights into sunitinib's mechanism of action in SFT patients.
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Affiliation(s)
- Rosalin D Spagnuolo
- Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Silvia Brich
- MOSE-DEA, University of Trieste, Trieste, Italy.,Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Fabio Bozzi
- Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Elena Conca
- Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Chiara Castelli
- Department of Experimental Oncology and Molecular Medicine, Unit of Immunotherapy of Human Tumours, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Marcella Tazzari
- Department of Experimental Oncology and Molecular Medicine, Unit of Immunotherapy of Human Tumours, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Roberta Maestro
- Experimental Oncology 1, Centro di Riferimento Oncologico, Aviano, Italy
| | - Monica Brenca
- Experimental Oncology 1, Centro di Riferimento Oncologico, Aviano, Italy
| | - Ambra V Gualeni
- Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Annunziata Gloghini
- Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Silvia Stacchiotti
- Adult Mesenchymal Tumour and Rare Cancer Medical Oncology Unit, Cancer Medicine Department, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Marco A Pierotti
- Scientific Directorate, Fondazione Città della Speranza, Padua, Italy
| | - Silvana Pilotti
- Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Tiziana Negri
- Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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Ravegnini G, Sammarini G, Nannini M, Pantaleo MA, Biasco G, Hrelia P, Angelini S. Gastrointestinal stromal tumors (GIST): Facing cell death between autophagy and apoptosis. Autophagy 2017; 13:452-463. [PMID: 28055310 DOI: 10.1080/15548627.2016.1256522] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Autophagy and apoptosis are 2 fundamental biological mechanisms that may cooperate or be antagonistic, although both are involved in deciding the fate of cells in physiological or pathological conditions. These 2 mechanisms coexist simultaneously in cells and share common upstream signals and stimuli. Autophagy and apoptosis play pivotal roles in cancer development. Autophagy plays a key function in maintaining tumor cell survival by providing energy during unfavorable metabolic conditions through its recycling mechanism, and supporting the high energy requirement for metabolism and growth. This review focuses on gastrointestinal stromal tumors and cell death through autophagy and apoptosis, taking into account the involvement of both of these processes in tumor development and growth and as mechanisms of drug resistance. We also focus on the crosstalk between autophagy and apoptosis as an emerging field with major implications for the development of novel therapeutic options.
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Affiliation(s)
- Gloria Ravegnini
- a Department of Pharmacy and Biotechnology , University of Bologna , Bologna Italy
| | - Giulia Sammarini
- a Department of Pharmacy and Biotechnology , University of Bologna , Bologna Italy
| | - Margherita Nannini
- b Department of Specialized , Experimental and Diagnostic Medicine, Sant'Orsola-Malpighi Hospital, University of Bologna , Bologna , Italy
| | - Maria A Pantaleo
- b Department of Specialized , Experimental and Diagnostic Medicine, Sant'Orsola-Malpighi Hospital, University of Bologna , Bologna , Italy.,c "Giorgio Prodi" Cancer Research Center, University of Bologna , Bologna , Italy
| | - Guido Biasco
- b Department of Specialized , Experimental and Diagnostic Medicine, Sant'Orsola-Malpighi Hospital, University of Bologna , Bologna , Italy.,c "Giorgio Prodi" Cancer Research Center, University of Bologna , Bologna , Italy
| | - Patrizia Hrelia
- a Department of Pharmacy and Biotechnology , University of Bologna , Bologna Italy
| | - Sabrina Angelini
- a Department of Pharmacy and Biotechnology , University of Bologna , Bologna Italy
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Mukhopadhyay S, Sinha N, Das DN, Panda PK, Naik PP, Bhutia SK. Clinical relevance of autophagic therapy in cancer: Investigating the current trends, challenges, and future prospects. Crit Rev Clin Lab Sci 2016; 53:228-52. [PMID: 26743568 DOI: 10.3109/10408363.2015.1135103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Oncophagy (cancer-related autophagy) has a complex dual character at different stages of tumor progression. It remains an important clinical problem to unravel the reasons that propel the shift in the role of oncophagy from tumor inhibition to a protective mechanism that shields full-blown malignancy. Most treatment strategies emphasize curbing protective oncophagy while triggering the oncophagy that is lethal to tumor cells. In this review, we focus on the trends in current therapeutics as well as various challenges in clinical trials to address the oncophagic dilemma and evaluate the potential of these developing therapies. A detailed analysis of the clinical and pre-clinical scenario of the anticancer medicines highlights the various inducers and inhibitors of autophagy. The ways in which tumor stage, the microenvironment and combination drug treatment continue to play an important tactical role are discussed. Moreover, autophagy targets also play a crucial role in developing the best possible solution to this oncophagy paradox. In this review, we provide a comprehensive update on the current clinical impact of autophagy-based cancer therapeutic drugs and try to lessen the gap between translational medicine and clinical science.
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Affiliation(s)
- Subhadip Mukhopadhyay
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
| | - Niharika Sinha
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
| | - Durgesh Nandini Das
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
| | - Prashanta Kumar Panda
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
| | - Prajna Paramita Naik
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
| | - Sujit Kumar Bhutia
- a Department of Life Science , National Institute of Technology , Rourkela , Odisha , India
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12
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Rutkowski P, Debiec-Rychter M. Current treatment options for dermatofibrosarcoma protuberans. Expert Rev Anticancer Ther 2015; 15:901-9. [PMID: 26027711 DOI: 10.1586/14737140.2015.1052799] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dermatofibrosarcoma protuberans (DFSP) is rare, infiltrating dermal neoplasm, characterized by indolent growth and low probability of metastases. The critical event in DFSP development is the rearrangement of chromosome 17 and 22, leading to transcriptional up-regulation of platelet-derived growth factor, providing an autocrine and/or paracrine stimulus. The cornerstone of treatment for localized DFSP is complete surgical resection with microscopically negative margins. Adjuvant radiotherapy is suggested in cases of positive margins when re-excision is not feasible. The first effective systemic therapy in DFSP introduced into clinical practice was imatinib, demonstrating dramatic activity in advanced cases. Current results indicate that some DFSP patient initially evaluated as unresectable/metastatic or necessitating mutilating surgery turned resectable after imatinib therapy and this rational approach leading to complete remission maybe potentially curative. The clinical experience with other tyrosine kinase inhibitors is limited and imatinib remains the gold standard treatment of locally unresectable/metastatic DFSP. This review summarizes state of the art and perspectives on the DFSP management.
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Affiliation(s)
- Piotr Rutkowski
- Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland
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A 32-month follow-up study of nanovesicle concentrations in blood from 12 patients with gastrointestinal stromal tumour treated with imatinib. Biochem Soc Trans 2013; 41:303-8. [DOI: 10.1042/bst20120247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Clinical studies have indicated that the NV (nanovesicle) concentration in blood samples is a potential indicator of clinical status and can be used to follow the development of the disease. For 32 months, we monitored the effect of imatinib treatment on NV concentrations in blood samples from 12 patients with GIST (gastrointestinal stromal tumour). The NV concentration before the treatment increased with respect to control by a factor of 3.5 on average (range 2.6–9.2). The first week after initiation of the treatment, the NV concentration increased considerably, by a factor of 13 on average (range 5.9–21.2), whereas on average, after 1 month, it decreased to the level of the control and remained at that level for at least 1.5 years. Recent assessment (after 2.5 years) showed a somewhat increased NV concentration, by a factor of 2 on average (range 0.7–3.9). Low NV concentrations in blood samples during the treatment reflect a favourable effect of imatinib in these patients and no remission of the disease was hitherto observed.
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Orlotti NI, Cimino-Reale G, Borghini E, Pennati M, Sissi C, Perrone F, Palumbo M, Daidone MG, Folini M, Zaffaroni N. Autophagy acts as a safeguard mechanism against G-quadruplex ligand-mediated DNA damage. Autophagy 2012; 8:1185-96. [PMID: 22627293 DOI: 10.4161/auto.20519] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
G-quadruplex ligands have attracted considerable interest as novel anticancer therapeutics due to their capability to interfere with guanosine-rich DNA/RNA sequences, such as telomeres. Elucidation of the structures of telomeric G-quadruplexes has led, in the past few years, to the rational development of effective G-quadruplex-stabilizing small molecules. In the present study, we showed that short-term exposure of melanoma cells to Ant1,5--an anthracene-based ligand able to stabilize telomeric G-quadruplexes--impaired cell growth without inducing cell senescence or apoptosis. Conversely, drug-treated cells were characterized by the occurrence of typical biochemical and morphological features associated with autophagy, such as an increase in the lipidated form of the autophagic marker LC3B and the accumulation of autophagosomes. Such drug-induced autophagy occurred as a consequence of DNA damage induction, at least in part dependent on drug-mediated telomere uncapping, through a pathway converging on the cyclin-dependent kinase inhibitor 1A (CDKN1A/p21). Indeed, melanoma cells depleted for CDKN1A did not show evidence of autophagic markers upon exposure to Ant1,5. The inhibition of autophagy by a pharmacologic inhibitor or through RNAi-mediated depletion of the ATG5 gene enhanced the cytotoxic activity of Ant1,5, as revealed by the marked increase in drug-induced apoptosis. Our data outline a molecular scenario in which G-quadruplex ligand-induced telomeric dysfunctions and DNA damage are translated into an autophagic response and provide the first evidence of autophagy as a safeguard mechanism activated by melanoma cells to counteract G-quadruplex ligand-mediated cellular stress.
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Affiliation(s)
- Nicola Ivan Orlotti
- Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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Da Riva L, Bozzi F, Mondellini P, Miccichè F, Fumagalli E, Vaghi E, Tarantino E, Huber V, Gronchi A, Tamborini E, Pierotti MA, Pilotti S, Bongarzone I. Proteomic detection of a large amount of SCGFα in the stroma of GISTs after imatinib therapy. J Transl Med 2011; 9:158. [PMID: 21943129 PMCID: PMC3192683 DOI: 10.1186/1479-5876-9-158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 09/23/2011] [Indexed: 01/24/2023] Open
Abstract
Background Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors to develop in the digestive tract. These tumors are highly resistant to conventional chemotherapy and only the introduction of imatinib mesylate has improved the prognosis of patients. However, Response Evaluation Criteria in Solid Tumors are inappropriate for assessing tumor response, and the histological/pathological response to imatinib is variable, heterogeneous, and does not associate with clinical response. The effects of imatinib on responding GISTs are still being explored, and few studies correlate the clinical response with the histological response after pharmacological treatment. Recently, apoptosis and autophagy were suggested as possible alternative mechanisms of pharmacological response. Methods Here, we used a proteomic approach, combined with other analyses, to identify some molecular stromal components related to the response/behavior of resected, high-risk GISTs after neoadiuvant imatinib therapy. Results Our proteomic results indicate an elevated concentration of Stem Cell Growth Factor (SCGF), a hematopoietic growth factor having a role in the development of erythroid and myeloid progenitors, in imatinib-responsive tumor areas. SCGFα expression was detected by mass spectrometry, immunohistochemistry and/or western blot and attributed to acellular matrix of areas scored negative for KIT (CD117). RT-PCR results indicated that GIST samples did not express SCGF transcripts. The recently reported demonstration by Gundacker et al. [1] of the secretion of SCGF in mature pro-inflammatory dendritic cells would indicate a potential importance of SCGF in tissue inflammatory response. Accordingly, inflammatory infiltrates were detected in imatinib-affected areas and the CD68-positivity of the SCGF-positive and KIT-negative areas suggested previous infiltration of monocytes/macrophages into these regions. Thus, chronic inflammation subsequent to imatinib treatment may determine monocyte/macrophage recruitment in imatinib-damaged areas; these areas also feature prominent tumor-cell loss that is replaced by dense hyalinization and fibrosis. Conclusions Our studies highlight a possible role of SCGFα in imatinib-induced changes of GIST structure, consistent with a therapeutic response.
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Affiliation(s)
- Luca Da Riva
- Proteomics Laboratory, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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16
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Stacchiotti S, Pedeutour F, Negri T, Conca E, Marrari A, Palassini E, Collini P, Keslair F, Morosi C, Gronchi A, Pilotti S, Casali PG. Dermatofibrosarcoma protuberans-derived fibrosarcoma: Clinical history, biological profile and sensitivity to imatinib. Int J Cancer 2011; 129:1761-72. [DOI: 10.1002/ijc.25826] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 11/02/2010] [Indexed: 11/06/2022]
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Crowley LC, Elzinga BM, O'Sullivan GC, McKenna SL. Autophagy induction by Bcr-Abl-expressing cells facilitates their recovery from a targeted or nontargeted treatment. Am J Hematol 2011; 86:38-47. [PMID: 21132731 DOI: 10.1002/ajh.21914] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although Imatinib has transformed the treatment of chronic myeloid leukemia (CML), it is not curative due to the persistence of resistant cells that can regenerate the disease. We have examined how Bcr-Abl-expressing cells respond to two mechanistically different therapeutic agents, etoposide and Imatinib. We also examined Bcr-Abl expression at low and high levels as elevated expression has been associated with treatment failure. Cells expressing low levels of Bcr-Abl undergo apoptosis in response to the DNA-targeting agent (etoposide), whereas high-Bcr-Abl-expressing cells primarily induce autophagy. Autophagic populations engage a delayed nonapoptotic death; however, sufficient cells evade this and repopulate following the withdrawal of the drug. Non-Bcr-Abl-expressing 32D or Ba/F3 cells induce both apoptosis and autophagy in response to etoposide and can recover. Imatinib treatment induces both apoptosis and autophagy in all Bcr-Abl-expressing cells and populations rapidly recover. Inhibition of autophagy with ATG7 and Beclin1 siRNA significantly reduced the recovery of Imatinib-treated K562 cells, indicating the importance of autophagy for the recovery of treated cells. Combination regimes incorporating agents that disrupt Imatinib-induced autophagy would remain primarily targeted and may improve response to the treatment in CML.
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MESH Headings
- Animals
- Autophagy/drug effects
- Autophagy/genetics
- Benzamides
- Cell Line, Tumor
- DNA Damage
- Doxorubicin/pharmacology
- Etoposide/pharmacology
- Fusion Proteins, bcr-abl/biosynthesis
- Fusion Proteins, bcr-abl/genetics
- Gene Knockdown Techniques
- Humans
- Imatinib Mesylate
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Mice
- Molecular Targeted Therapy/methods
- Piperazines/pharmacology
- Pyrimidines/pharmacology
- RNA, Small Interfering/administration & dosage
- RNA, Small Interfering/genetics
- Transfection
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Affiliation(s)
- Lisa C Crowley
- Leslie C. Quick Laboratory, Cork Cancer Research Centre, BioSciences Institute, University College Cork and Mercy University Hospital, Grenville Place, Cork, Ireland
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Synergistic induction of apoptosis by the Bcl-2 inhibitor ABT-737 and imatinib mesylate in gastrointestinal stromal tumor cells. Mol Oncol 2010; 5:93-104. [PMID: 21115411 DOI: 10.1016/j.molonc.2010.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 10/07/2010] [Accepted: 10/08/2010] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Although imatinib mesylate has revolutionized the management of patients with gastrointestinal stromal tumor (GIST), resistance and progression almost inevitably develop with long-term monotherapy. To enhance imatinib-induced cytotoxicity and overcome imatinib-resistance in GIST cells, we examined the antitumor effects of the pro-apoptotic Bcl-2/Bcl-x(L) inhibitor ABT-737, alone and in combination with imatinib. METHODS We treated imatinib-sensitive, GIST-T1 and GIST882, and imatinib-resistant cells with ABT-737 alone and with imatinib. We determined the anti-proliferative and apoptotic effects by cell viability assay, flow cytometric apoptosis and cell cycle analysis, immunoblotting, and nuclear morphology. Synergism was determined by isobologram analysis. RESULTS The IC(50) of single-agent ABT-737 at 72 h was 10 μM in imatinib-sensitive GIST-T1 and GIST882 cells, and 1 μM in imatinib-resistant GIST48IM cells. ABT-737 and imatinib combined synergistically in a time- and dose-dependent manner to inhibit the proliferation and induce apoptosis of all GIST cells, as evidenced by cell viability and apoptosis assays, caspase activation, PARP cleavage, and morphologic changes. Isobologram analyses revealed strongly synergistic drug interactions, with combination indices <0.5 for most ABT-737/imatinib combinations. Thus, clinically relevant in vitro concentrations of ABT-737 have single-agent antitumor activity and are synergistic in combination with imatinib. CONCLUSION We provide the first preclinical evidence that Bcl-2/Bcl-x(L) inhibition with ABT-737 synergistically enhances imatinib-induced cytotoxicity via apoptosis, and that direct engagement of apoptotic cell death may be an effective approach to circumvent imatinib-resistance in GIST.
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Gordon PM, Fisher DE. Role for the proapoptotic factor BIM in mediating imatinib-induced apoptosis in a c-KIT-dependent gastrointestinal stromal tumor cell line. J Biol Chem 2010; 285:14109-14. [PMID: 20231287 DOI: 10.1074/jbc.m109.078592] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The c-KIT receptor tyrosine kinase is constitutively activated and oncogenic in the majority of gastrointestinal stromal tumors. The identification of selective inhibitors of c-KIT, such as imatinib, has provided a novel therapeutic approach in the treatment of this chemotherapy refractory tumor. However, despite the clinical importance of these findings and the potential it provides as a model system for understanding targeted therapy, this approach has not yielded curative outcomes in most patients, and the biochemical pathways connecting c-KIT inhibition to cell death are not completely understood. Here, we show that inhibition of c-KIT with imatinib in gastrointestinal stromal tumors (GISTs) triggered the up-regulation of the proapoptotic protein BIM via both transcriptional and post-translational mechanisms. The inhibition of c-KIT by imatinib increased levels of the dephosphorylated and deubiquitinated form of BIM as well as triggered the accumulation of the transcription factor FOXO3a on the BIM promoter to activate transcription of BIM mRNA. Furthermore, using RNA interference directed against BIM, we demonstrated that BIM knockdown attenuated the effects of imatinib, suggesting that BIM functionally contributes to imatinib-induced apoptosis in GIST. The identification and characterization of the pathways that mediate imatinib-induced cell death in GIST provide for a better understanding of targeted therapy and may facilitate the development of new therapeutic approaches to further exploit these pathways.
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Affiliation(s)
- Peter M Gordon
- Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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Autophagy facilitates the development of breast cancer resistance to the anti-HER2 monoclonal antibody trastuzumab. PLoS One 2009; 4:e6251. [PMID: 19606230 PMCID: PMC2708925 DOI: 10.1371/journal.pone.0006251] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Accepted: 06/17/2009] [Indexed: 01/22/2023] Open
Abstract
Autophagy has been emerging as a novel cytoprotective mechanism to increase tumor cell survival under conditions of metabolic stress and hypoxia as well as to escape chemotherapy-induced cell death. To elucidate whether autophagy might also protect cancer cells from the growth inhibitory effects of targeted therapies, we evaluated the autophagic status of preclinical breast cancer models exhibiting auto-acquired resistance to the anti-HER2 monoclonal antibody trastuzumab (Tzb). We first examined the basal autophagic levels in Tzb-naive SKBR3 cells and in two pools of Tzb-conditioned SKBR3 cells (TzbR), which optimally grow in the presence of Tzb doses as high as 200 µg/ml Tzb. Fluorescence microscopic analyses revealed that the number of punctate LC3 structures -a hallmark of autophagy- was drastically higher in Tzb-refractory cells than in Tzb-sensitive SKBR3 parental cells. Immunoblotting analyses confirmed that the lipidation product of the autophagic conversion of LC3 was accumulated to high levels in TzbR cells. High levels of the LC3 lipidated form in Tzb-refractory cells were accompanied by decreased p62/sequestosome-1 protein expression, a phenomenon characterizing the occurrence of increased autophagic flux. Moreover, increased autophagy was actively used to survive Tzb therapy as TzbR pools were exquisitely sensitive to chemical inhibitors of autophagosomal formation/function. Knockdown of LC3 expression via siRNA similarly resulted in reduced TzbR cell proliferation and supra-additively interacted with Tzb to re-sensitize TzbR cells. Sub-groups of Tzb-naive SKBR3 parental cells accumulated LC3 punctate structures and decreased p62 expression after treatment with high-dose Tzb, likely promoting their own resistance. This is the first report showing that HER2-overexpressing breast cancer cells chronically exposed to Tzb exhibit a bona fide up-regulation of the autophagic activity that efficiently works to protect breast cancer cells from the growth-inhibitory effects of Tzb. Therapeutic targeting autophagosome formation/function might represent a novel molecular avenue to reduce the emergence of Tzb resistance in HER2-dependent breast carcinomas.
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