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Luan Z, He Y, He F, Chen Z. Rocaglamide overcomes tumor necrosis factor-related apoptosis-inducing ligand resistance in hepatocellular carcinoma cells by attenuating the inhibition of caspase-8 through cellular FLICE-like-inhibitory protein downregulation. Mol Med Rep 2014; 11:203-11. [PMID: 25333816 PMCID: PMC4237083 DOI: 10.3892/mmr.2014.2718] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 09/04/2014] [Indexed: 12/18/2022] Open
Abstract
The enhancement of apoptosis is a therapeutic strategy used in the treatment of cancer. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising antitumor agent. However, hepatocellular carcinoma (HCC) cells exhibit marked resistance to the induction of cell death by TRAIL. The present study investigated whether rocaglamide, a naturally occurring product isolated from the genus Aglaia, is able to sensitize resistant HCC cells to TRAIL-mediated apoptosis. Two HCC cell lines, HepG2 and Huh-7, were treated with rocaglamide and/or TRAIL and the induction of apoptosis and effects on the TRAIL signaling pathway were investigated. The in vivo efficacy of rocaglamide was determined in TRAIL-resistant Huh-7-derived tumor xenografts. Rocaglamide significantly sensitized the TRAIL-resistant HCC cells to apoptosis by TRAIL, which resulted from the rocaglamide-mediated downregulation of cellular FLICE-like inhibitory protein and subsequent caspase-8 activation. Furthermore, rocaglamide markedly inhibited tumor growth from Huh-7 cells propagated in severe combined immunodeficient mice, suggesting that chemosentization also occurred in vivo. These data suggest that rocaglamide acted synergistically with TRAIL against the TRAIL-resistant HCC cells. Thus, it is concluded that rocaglamide as an adjuvant to TRAIL-based therapy may present a promising therapeutic approach for the treatment of HCC.
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Affiliation(s)
- Zhou Luan
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Ying He
- Department of Ophthalmology, The Central Hospital of Wuhan, Wuhan, Hubei 430014, P.R. China
| | - Fan He
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Zhishui Chen
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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52
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Sarhan D, D'Arcy P, Lundqvist A. Regulation of TRAIL-receptor expression by the ubiquitin-proteasome system. Int J Mol Sci 2014; 15:18557-73. [PMID: 25318057 PMCID: PMC4227232 DOI: 10.3390/ijms151018557] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 12/21/2022] Open
Abstract
The tumor necrosis factor (TNF)-related apoptosis-inducing ligand- receptor (TRAIL-R) family has emerged as a key mediator of cell fate and survival. Ligation of TRAIL ligand to TRAIL-R1 or TRAIL-R2 initiates the extrinsic apoptotic pathway characterized by the recruitment of death domains, assembly of the death-inducing signaling complex (DISC), caspase activation and ultimately apoptosis. Conversely the decoy receptors TRAIL-R3 and TRAIL-R4, which lack the pro-apoptotic death domain, function to dampen the apoptotic response by competing for TRAIL ligand. The tissue restricted expression of the decoy receptors on normal but not cancer cells provides a therapeutic rational for the development of selective TRAIL-mediated anti-tumor therapies. Recent clinical trials using agonistic antibodies against the apoptosis-inducing TRAIL receptors or recombinant TRAIL have been promising; however the number of patients in complete remission remains stubbornly low. The mechanisms of TRAIL resistance are relatively unexplored but may in part be due to TRAIL-R down-regulation or shedding of TRAIL-R by tumor cells. Therefore a better understanding of the mechanisms underlying TRAIL resistance is required. The ubiquitin-proteasome system (UPS) has been shown to regulate TRAIL-R members suggesting that pharmacological inhibition of the UPS may be a novel strategy to augment TRAIL-based therapies and increase efficacies. We recently identified b-AP15 as an inhibitor of proteasome deubiquitinase (DUB) activity. Interestingly, exposure of tumor cell lines to b-AP15 resulted in increased TRAIL-R2 expression and enhanced sensitivity to TRAIL-mediated apoptosis and cell death in vitro and in vivo. In conclusion, targeting the UPS may represent a novel strategy to increase the cell surface expression of pro-apoptotic TRAIL-R on cancer cells and should be considered in clinical trials targeting TRAIL-receptors in cancer patients.
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Affiliation(s)
- Dhifaf Sarhan
- Karolinska Institutet, Department of Oncology-Pathology, Stockholm S-17176, Sweden.
| | - Padraig D'Arcy
- Karolinska Institutet, Department of Oncology-Pathology, Stockholm S-17176, Sweden.
| | - Andreas Lundqvist
- Karolinska Institutet, Department of Oncology-Pathology, Stockholm S-17176, Sweden.
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Goda AE, Erikson RL, Sakai T, Ahn JS, Kim BY. Preclinical evaluation of bortezomib/dipyridamole novel combination as a potential therapeutic modality for hematologic malignancies. Mol Oncol 2014; 9:309-22. [PMID: 25245324 DOI: 10.1016/j.molonc.2014.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022] Open
Abstract
Novel combinations aiming at maximizing the efficacy of bortezomib are highly valued in the clinic. Therefore the current study investigated the outcomes of combining bortezomib with dipyridamole, a well-known antiplatelet. The co-treatment exerted a synergistic lethality in a panel of human leukemia/lymphoma cell lines of different origin. Mechanistically, dipyridamole did not modulate the proteasome inhibitory activity of bortezomib. However, dipyridamole triggered an endoplasmic reticulum (ER) stress, and co-treatment with bortezomib resulted in higher levels of ER stress than either monotherapies. Relieving ER stress with the protein translation inhibitor, cycloheximide suppressed cell death. Moreover, the enhanced ER stress by the co-treatment was associated with an aggravation of reactive oxygen species (ROS) generation and glutathione (GSH) depletion. Replenishing GSH pools significantly scavenged ROS and rescued the cells. Importantly, the cytotoxicity of the co-treatment was executed mainly via the mitochondrial apoptotic pathway with an efficient suppression of the key anti-apoptotic regulators, Mcl-1, Bcl-xl, Bcl-2 and XIAP, driving the independence of the co-treatment-induced apoptosis of a single apoptotic trigger. Furthermore, the intrinsic potential of bortezomib to inhibit important pro-survival pathways was enhanced by dipyridamole in a GSH/ROS-dependent manner. Interestingly, dipyridamole abrogated JAK2 phosphorylation indirectly and selectively in cancer cells, and the co-treatment-induced cytotoxicity was preserved in a model of stromal-mediated chemoresistance. In nude mice, the antitumor activity of the co-treatment surpassed that of bortezomib monotherapy despite that synergy was lacking. In summary, findings of the present study provided a preclinical rationale which warrants further clinical evaluation of bortezomib/dipyridamole novel combination in hematologic malignancies.
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Affiliation(s)
- Ahmed E Goda
- World Class Institute, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 685-2 Ochang, Cheongwon 363-883, Republic of Korea; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta, Egypt.
| | - Raymond L Erikson
- World Class Institute, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 685-2 Ochang, Cheongwon 363-883, Republic of Korea; Department of Molecular and Cellular Biology, Harvard University, Cambridge, USA
| | - Toshiyuki Sakai
- Department of Molecular-Targeting Cancer Prevention, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Jong-Seog Ahn
- Chemical Biology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Ochang, Republic of Korea
| | - Bo-Yeon Kim
- World Class Institute, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 685-2 Ochang, Cheongwon 363-883, Republic of Korea.
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Sotiropoulou PA, Christodoulou MS, Silvani A, Herold-Mende C, Passarella D. Chemical approaches to targeting drug resistance in cancer stem cells. Drug Discov Today 2014; 19:1547-62. [PMID: 24819719 DOI: 10.1016/j.drudis.2014.05.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/24/2014] [Accepted: 05/01/2014] [Indexed: 12/16/2022]
Abstract
Cancer stem cells (CSCs) are a subpopulation of cancer cells with high clonogenic capacity and ability to reform parental tumors upon transplantation. Resistance to therapy has been shown for several types of CSC and, therefore, they have been proposed as the cause of tumor relapse. Consequently, much effort has been made to design molecules that can target CSCs specifically and sensitize them to therapy. In this review, we summarize the mechanisms underlying CSC resistance, the potential biological targets to overcome resistance and the chemical compounds showing activity against different types of CSC. The chemical compounds discussed here have been divided according to their origin: natural, natural-derived and synthetic compounds.
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Affiliation(s)
- Panagiota A Sotiropoulou
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles (ULB), 808 route de Lennik, BatC, 1070 Bruxelles, Belgium
| | - Michael S Christodoulou
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Alessandra Silvani
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Christel Herold-Mende
- Division of Experimental Neurosurgery, Department of Neurosurgery, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Daniele Passarella
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy.
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Friesen C, Hormann I, Roscher M, Fichtner I, Alt A, Hilger R, Debatin KM, Miltner E. Opioid receptor activation triggering downregulation of cAMP improves effectiveness of anti-cancer drugs in treatment of glioblastoma. Cell Cycle 2014; 13:1560-70. [PMID: 24626197 PMCID: PMC4050161 DOI: 10.4161/cc.28493] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Glioblastoma are the most frequent and malignant human brain tumors, having a very poor prognosis. The enhanced radio- and chemoresistance of glioblastoma and the glioblastoma stem cells might be the main reason why conventional therapies fail. The second messenger cyclic AMP (cAMP) controls cell proliferation, differentiation, and apoptosis. Downregulation of cAMP sensitizes tumor cells for anti-cancer treatment. Opioid receptor agonists triggering opioid receptors can activate inhibitory Gi proteins, which, in turn, block adenylyl cyclase activity reducing cAMP. In this study, we show that downregulation of cAMP by opioid receptor activation improves the effectiveness of anti-cancer drugs in treatment of glioblastoma. The µ-opioid receptor agonist D,L-methadone sensitizes glioblastoma as well as the untreatable glioblastoma stem cells for doxorubicin-induced apoptosis and activation of apoptosis pathways by reversing deficient caspase activation and deficient downregulation of XIAP and Bcl-xL, playing critical roles in glioblastomas’ resistance. Blocking opioid receptors using the opioid receptor antagonist naloxone or increasing intracellular cAMP by 3-isobutyl-1-methylxanthine (IBMX) strongly reduced opioid receptor agonist-induced sensitization for doxorubicin. In addition, the opioid receptor agonist D,L-methadone increased doxorubicin uptake and decreased doxorubicin efflux, whereas doxorubicin increased opioid receptor expression in glioblastomas. Furthermore, opioid receptor activation using D,L-methadone inhibited tumor growth significantly in vivo. Our findings suggest that opioid receptor activation triggering downregulation of cAMP is a promising strategy to inhibit tumor growth and to improve the effectiveness of anti-cancer drugs in treatment of glioblastoma and in killing glioblastoma stem cells.
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Affiliation(s)
- Claudia Friesen
- Center for Biomedical Research; University of Ulm; Ulm, Germany; Institute of Legal Medicine; University of Ulm; Ulm, Germany
| | - Inis Hormann
- Center for Biomedical Research; University of Ulm; Ulm, Germany; Institute of Legal Medicine; University of Ulm; Ulm, Germany
| | - Mareike Roscher
- Center for Biomedical Research; University of Ulm; Ulm, Germany; Institute of Legal Medicine; University of Ulm; Ulm, Germany
| | - Iduna Fichtner
- Max Delbrueck Center for Molecular Medicine; Berlin, Germany
| | - Andreas Alt
- Institute of Legal Medicine; University of Ulm; Ulm, Germany
| | - Ralf Hilger
- Department of Internal Medicine; University of Essen; West German Cancer Center; Essen, Germany
| | | | - Erich Miltner
- Center for Biomedical Research; University of Ulm; Ulm, Germany; Institute of Legal Medicine; University of Ulm; Ulm, Germany
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56
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Tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 818:167-80. [PMID: 25001536 DOI: 10.1007/978-1-4471-6458-6_8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The concept to exploit death receptors for cancer therapy is very attractive, since these cell surface receptors have a direct connection to the intracellular cell death machinery. Among the death receptor superfamily, the tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) receptor/ligand system is of special interest. TRAIL receptor agonists have recently entered the stage of clinical evaluation for the treatment of human cancers. Further insights into the regulatory mechanisms of TRAIL signaling will help to better understand the determinants of TRAIL sensitivity versus resistance of human cancers.
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57
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Beranova L, Pombinho AR, Spegarova J, Koc M, Klanova M, Molinsky J, Klener P, Bartunek P, Andera L. The plant alkaloid and anti-leukemia drug homoharringtonine sensitizes resistant human colorectal carcinoma cells to TRAIL-induced apoptosis via multiple mechanisms. Apoptosis 2013; 18:739-50. [PMID: 23456623 DOI: 10.1007/s10495-013-0823-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
TNF-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic ligand from the TNF-alpha family that is under consideration, along with agonistic anti-TRAIL receptor antibodies, as a potential anti-tumor agent. However, most primary human tumors are resistant to monotherapy with TRAIL apoptogens, and thus the potential applicability of TRAIL in anti-tumor therapy ultimately depends on its rational combination with drugs targeting these resistances. In our high-throughput screening for novel agents/drugs that could sensitize TRAIL-resistant colorectal cancer cells to TRAIL-induced apoptosis, we found homoharringtonine (HHT), a cephalotaxus alkaloid and tested anti-leukemia drug, to be a very effective, low nanomolar enhancer of TRAIL-mediated apoptosis/growth suppression of these resistant cells. Co-treatment of TRAIL-resistant RKO or HT-29 cells with HHT and TRAIL led to the effective induction of apoptosis and the complete elimination of the treated cells. HHT suppressed the expression of the anti-apoptotic proteins Mcl-1 and cFLIP and enhanced the TRAIL-triggered activation of JNK and p38 kinases. The shRNA-mediated down-regulation of cFLIP or Mcl-1 in HT-29 or RKO cells variably enhanced their TRAIL-induced apoptosis but it did not markedly sensitize them to TRAIL-mediated growth suppression. However, with the notable exception of RKO/sh cFLIP cells, the downregulation of cFLIP or Mcl-1 significantly lowered the effective concentration of HHT in HHT + TRAIL co-treatment. Combined HHT + TRAIL therapy also led to the strong suppression of HT-29 tumors implanted into immunodeficient mice. Thus, HHT represents a very efficient enhancer of TRAIL-induced apoptosis with potential application in TRAIL-based, anti-cancer combination therapy.
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Affiliation(s)
- Lenka Beranova
- Department of Cell Signaling & Apoptosis, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Praha 4, Czech Republic
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58
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Rapino F, Naumann I, Fulda S. Bortezomib antagonizes microtubule-interfering drug-induced apoptosis by inhibiting G2/M transition and MCL-1 degradation. Cell Death Dis 2013; 4:e925. [PMID: 24263099 PMCID: PMC3847318 DOI: 10.1038/cddis.2013.440] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 09/17/2013] [Accepted: 10/01/2013] [Indexed: 01/27/2023]
Abstract
Inhibition of the proteasome is considered as a promising strategy to sensitize cancer cells to apoptosis. Recently, we demonstrated that the proteasome inhibitor Bortezomib primes neuroblastoma cells to TRAIL-induced apoptosis. In the present study, we investigated whether Bortezomib increases chemosensitivity of neuroblastoma cells. Unexpectedly, we discover an antagonistic interaction of Bortezomib and microtubule-interfering drugs. Bortezomib significantly attenuates the loss of cell viability and induction of apoptosis on treatment with Taxol and different vinca alkaloids but not with other chemotherapeutics, that is, Doxorubicin and Cisplatinum. Importantly, Bortezomib inhibits G2/M transition by inhibiting proteasomal degradation of cell cycle regulatory proteins such as p21, thereby preventing cells to enter mitosis, the cell cycle phase in which they are most vulnerable to antitubulin chemotherapeutics. Consequently, Bortezomib counteracts Taxol-induced mitotic arrest and polyploidy, as shown by reduced expression of PLK1 and phosphorylated histone H3. In addition, Bortezomib antagonizes Taxol-mediated degradation of MCL-1 during mitotic arrest by preventing cells to enter mitosis and by inhibiting the proteasome. Downregulation of MCL-1 is critically required for Taxol-induced apoptosis, as overexpression of a phosphomutant MCL-1 variant, which is resistant to degradation, significantly diminishes Taxol-triggered apoptosis. Vice versa, attenuation of Bortezomib-mediated accumulation of MCL-1 by knockdown of MCL-1 significantly enhances Taxol/Bortezomib-induced apoptosis. Thus, Bortezomib rescues Taxol-induced apoptosis by inhibiting G2/M transition and mitigating MCL-1 degradation. The identification of this antagonistic interaction of Bortezomib and microtubule-targeted drugs has important implications for the design of Bortezomib-based combination therapies.
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Affiliation(s)
- F Rapino
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University Frankfurt, Komturstr. 3a, Frankfurt, Germany
| | - I Naumann
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University Frankfurt, Komturstr. 3a, Frankfurt, Germany
| | - S Fulda
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University Frankfurt, Komturstr. 3a, Frankfurt, Germany
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59
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Specific expression of k63-linked ubiquitination of calmodulin-like protein 5 in breast cancer of premenopausal patients. J Cancer Res Clin Oncol 2013; 139:2125-32. [PMID: 24146193 DOI: 10.1007/s00432-013-1541-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 10/10/2013] [Indexed: 01/18/2023]
Abstract
PURPOSE Posttranslational modifications such as ubiquitination regulate many functions of proteins by affecting their interaction with other molecules, their activity, and their subcellular localization. In cancer biology, the ubiquitin network has gained major interest. K63-linked ubiquitination has emerged as a posttranslational modification with functional consequences, as it acts in several processes such as protein trafficking, DNA repair, and inflammation. Moreover, k63-linked ubiquitination is involved in the regulation of carcinogenesis. Based on previous findings, the aim of this study was to evaluate the ubiquitination of CALML5 in breast cancer patients. PATIENTS AND METHODS The breast cancer cell lines SkBr3, MCF7, HCC1937, and BT474 as well as 23 tumor samples of patients with primary breast cancer and the normal adjacent breast tissue were analyzed by one-dimensional immunoblot. RESULTS Using specific antibodies against CALML5 and k63-linked ubiquitin, we demonstrate a k63-linked ubiquitination in the nuclear fraction of premenopausal breast cancer patients. K63-linked ubiquitination of CALML5 was found in breast cancer tissue, but not found in surrounding healthy tissue. CONCLUSION Our findings support the concept that ubiquitination of CALML5 in the nucleus is involved in the carcinogenesis of breast cancer in premenopausal women.
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60
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Bortezomib overcomes MGMT-related resistance of glioblastoma cell lines to temozolomide in a schedule-dependent manner. Invest New Drugs 2013; 31:1169-81. [DOI: 10.1007/s10637-013-9968-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 04/24/2013] [Indexed: 10/26/2022]
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Manini I, Sgorbissa A, Potu H, Tomasella A, Brancolini C. The DeISGylase USP18 limits TRAIL-induced apoptosis through the regulation of TRAIL levels: Cellular levels of TRAIL influences responsiveness to TRAIL-induced apoptosis. Cancer Biol Ther 2013; 14:1158-66. [PMID: 24153058 DOI: 10.4161/cbt.26525] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a promising molecule for anti-cancer therapies. Unfortunately, cancer cells frequently acquire resistance to rhTRAIL. Various co-treatments have been proposed to overcome apoptosis resistance to TRAIL. Here we show that downregulation of the deISGylase USP18 sensitizes cancer cells to rhTRAIL, whereas, elevate levels of USP18 inhibit TRAIL-induced apoptosis, in a deISGylase-independent manner. USP18 influences TRAIL signaling through the control of the IFN autocrine loop. In fact, cells with downregulated USP18 expression augment the expression of cellular TRAIL. Downregulation of cellular TRAIL abrogates the synergism between TRAIL and USP18 siRNA and also limits cell death induced by rhTRAIL. By comparing the apoptotic responsiveness to TRAIL in a panel of cancer cell lines, we have discovered a correlation between TRAIL levels and the apoptotic susceptibility to rhTRAIL, In cells expressing high levels of TRAIL-R2 susceptibility to rhTRAIL correlates with TRAIL expression. In conclusion, we propose that cellular TRAIL is an additional factor that can influence the apoptotic response to rhTRAIL.
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Affiliation(s)
- Ivana Manini
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence; Università degli Studi di Udine; Udine, Italy
| | - Andrea Sgorbissa
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence; Università degli Studi di Udine; Udine, Italy
| | - Harish Potu
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence; Università degli Studi di Udine; Udine, Italy
| | - Andrea Tomasella
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence; Università degli Studi di Udine; Udine, Italy
| | - Claudio Brancolini
- Dipartimento di Scienze Mediche e Biologiche and MATI Center of Excellence; Università degli Studi di Udine; Udine, Italy
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62
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Vlachostergios PJ, Voutsadakis IA, Papandreou CN. Mechanisms of proteasome inhibitor-induced cytotoxicity in malignant glioma. Cell Biol Toxicol 2013; 29:199-211. [PMID: 23733249 DOI: 10.1007/s10565-013-9248-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 05/23/2013] [Indexed: 12/12/2022]
Abstract
The 26S proteasome constitutes an essential degradation apparatus involved in the consistent recycling of misfolded and damaged proteins inside cells. The aberrant activation of the proteasome has been widely observed in various types of cancers and implicated in the development and progression of carcinogenesis. In the era of targeted therapies, the clinical use of proteasome inhibitors necessitates a better understanding of the molecular mechanisms of cell death responsible for their cytotoxic action, which are reviewed here in the context of sensitization of malignant gliomas, a tumor type particularly refractory to conventional treatments.
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Affiliation(s)
- Panagiotis J Vlachostergios
- Department of Medical Oncology, Faculty of Medicine, University of Thessaly, University Hospital of Larissa, Larissa, 41110, Greece.
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63
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Eißmann M, Schwamb B, Melzer IM, Moser J, Siele D, Köhl U, Rieker RJ, Wachter DL, Agaimy A, Herpel E, Baumgarten P, Mittelbronn M, Rakel S, Kögel D, Böhm S, Gutschner T, Diederichs S, Zörnig M. A functional yeast survival screen of tumor-derived cDNA libraries designed to identify anti-apoptotic mammalian oncogenes. PLoS One 2013; 8:e64873. [PMID: 23717670 PMCID: PMC3661464 DOI: 10.1371/journal.pone.0064873] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 04/19/2013] [Indexed: 11/29/2022] Open
Abstract
Yeast cells can be killed upon expression of pro-apoptotic mammalian proteins. We have established a functional yeast survival screen that was used to isolate novel human anti-apoptotic genes overexpressed in treatment-resistant tumors. The screening of three different cDNA libraries prepared from metastatic melanoma, glioblastomas and leukemic blasts allowed for the identification of many yeast cell death-repressing cDNAs, including 28% of genes that are already known to inhibit apoptosis, 35% of genes upregulated in at least one tumor entity and 16% of genes described as both anti-apoptotic in function and upregulated in tumors. These results confirm the great potential of this screening tool to identify novel anti-apoptotic and tumor-relevant molecules. Three of the isolated candidate genes were further analyzed regarding their anti-apoptotic function in cell culture and their potential as a therapeutic target for molecular therapy. PAICS, an enzyme required for de novo purine biosynthesis, the long non-coding RNA MALAT1 and the MAST2 kinase are overexpressed in certain tumor entities and capable of suppressing apoptosis in human cells. Using a subcutaneous xenograft mouse model, we also demonstrated that glioblastoma tumor growth requires MAST2 expression. An additional advantage of the yeast survival screen is its universal applicability. By using various inducible pro-apoptotic killer proteins and screening the appropriate cDNA library prepared from normal or pathologic tissue of interest, the survival screen can be used to identify apoptosis inhibitors in many different systems.
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Affiliation(s)
- Moritz Eißmann
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Bettina Schwamb
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Inga Maria Melzer
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Julia Moser
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Dagmar Siele
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Ulrike Köhl
- Institute of Cellular Therapeutics, IFB-Tx, Hannover Medical School, Hannover, Germany
| | | | | | - Abbas Agaimy
- Institute for Pathology, University Hospital Erlangen, Erlangen, Germany
| | - Esther Herpel
- Institute of Pathology, University of Heidelberg, Heidelberg, Germany
| | - Peter Baumgarten
- Institute of Neurology (Edinger Institute), Frankfurt/Main, Germany
| | | | - Stefanie Rakel
- Experimental Neurosurgery, Center for Neurology and Neurosurgery, Goethe University Hospital Frankfurt, Frankfurt/Main, Germany
| | - Donat Kögel
- Experimental Neurosurgery, Center for Neurology and Neurosurgery, Goethe University Hospital Frankfurt, Frankfurt/Main, Germany
| | - Stefanie Böhm
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
| | - Tony Gutschner
- Helmholtz-University-Group Molecular RNA Biology & Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Sven Diederichs
- Helmholtz-University-Group Molecular RNA Biology & Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin Zörnig
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Frankfurt/Main, Germany
- * E-mail:
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64
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Identification of non-canonical NF-κB signaling as a critical mediator of Smac mimetic-stimulated migration and invasion of glioblastoma cells. Cell Death Dis 2013; 4:e564. [PMID: 23538445 PMCID: PMC3615728 DOI: 10.1038/cddis.2013.70] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As inhibitor of apoptosis (IAP) proteins can regulate additional signaling pathways beyond apoptosis, we investigated the effect of the second mitochondrial activator of caspases (Smac) mimetic BV6, which antagonizes IAP proteins, on non-apoptotic functions in glioblastoma (GBM). Here, we identify non-canonical nuclear factor-κB (NF-κB) signaling and a tumor necrosis factor-α (TNFα)/TNF receptor 1 (TNFR1) autocrine/paracrine loop as critical mediators of BV6-stimulated migration and invasion of GBM cells. In addition to GBM cell lines, BV6 triggers cell elongation, migration and invasion in primary, patient-derived GBM cells at non-toxic concentrations, which do not affect cell viability or proliferation, and also increases infiltrative tumor growth in vivo underscoring the relevance of these findings. Molecular studies reveal that BV6 causes rapid degradation of cellular IAP proteins, accumulation of NIK, processing of p100 to p52, translocation of p52 into the nucleus, increased NF-κB DNA binding and enhanced NF-κB transcriptional activity. Electrophoretic mobility shift assay supershift shows that the NF-κB DNA-binding subunits consist of p50, p52 and RelB further confirming the activation of the non-canonical NF-κB pathway. BV6-stimulated NF-κB activation leads to elevated mRNA levels of TNFα and additional NF-κB target genes involved in migration (i.e., interleukin 8, monocyte chemoattractant protein 1, CXC chemokine receptor 4) and invasion (i.e., matrix metalloproteinase-9). Importantly, inhibition of NF-κB by overexpression of dominant-negative IκBα superrepressor prevents the BV6-stimulated cell elongation, migration and invasion. Similarly, specific inhibition of non-canonical NF-κB signaling by RNA interference-mediated silencing of NIK suppresses the BV6-induced cell elongation, migration and invasion as well as upregulation of NF-κB target genes. Intriguingly, pharmacological or genetic inhibition of the BV6-stimulated TNFα autocrine/paracrine loop by the TNFα-blocking antibody Enbrel or by knockdown of TNFR1 abrogates BV6-induced cell elongation, migration and invasion. By demonstrating that the Smac mimetic BV6 at non-toxic concentrations promotes migration and invasion of GBM cells via non-canonical NF-κB signaling, our findings have important implications for the use of Smac mimetics as cancer therapeutics.
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Bortezomib Downregulates MGMT Expression in T98G Glioblastoma Cells. Cell Mol Neurobiol 2013; 33:313-8. [DOI: 10.1007/s10571-013-9910-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 01/09/2013] [Indexed: 01/11/2023]
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Abstract
Deregulation of gene expression, a hallmark of cancer, is caused by both genetic and epigenetic mechanisms. The rapid accumulation of epigenome maps of various cancers suggests a new avenue of research, namely integrating epigenomic data with other types of omic data for cancer diagnosis, prognosis, and biomarker discovery. We introduce the MAPIT algorithm (Multi Analyte Pathway Inference Tool), to enable principled integration of epigenomic, transcriptomic, and protein interactome data. As a proof-of-principle, we apply MAPIT to glioblastoma multiforme (GBM), the most common and aggressive form of brain tumor. Few predictive markers were reported for the prognosis of GBM patients. By integrating mRNA transcriptome, promoter DNA methylome and protein-protein physical interactome, we find ten expression- and three methylation-based network markers, involving 118 genes. When tested on additional GBM patient samples, the prognostic accuracy of the multi-analyte network markers (73.5%) is 9.7% and 8.6% higher than previous prognostic signatures built on gene expression or DNA methylation alone. Our results highlight the critical role of two novel pathways in the prognosis of GBM patients, small GTPase-mediated protein trafficking and ubiquitination-dependent protein degradation. A better understanding of these two pathways could lead to personalized therapies for subgroups of GBM patients. Our study demonstrates that integrating epigenomic, transcriptomic, and interactomic data can improve the accuracy network-based prognosis markers and lead to novel mechanistic understanding of cancer.
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Affiliation(s)
- Jongkwang Kim
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Long Gao
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - Kai Tan
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Abstract
INTRODUCTION Evasion of apoptosis (programmed cell death) is one of the characteristic hallmarks of human cancers and may be caused by aberrant expression of antiapoptotic proteins. Among those is c-FLICE-like inhibitory protein (c-FLIP), a protein that not only blocks apoptosis signaling but also regulates additional cell death pathways. AREAS COVERED Because c-FLIP is regulated both at the transcriptional and posttranscriptional level by various mechanisms and is a short-lived protein with a rapid turnover, the regulation of c-FLIP expression represents a versatile tool to modulate cell death signaling pathways. Because c-FLIP is aberrantly expressed in various cancers, it represents a promising target for therapeutic intervention. EXPERT OPINION Therefore, insights into the molecular events that regulate c-FLIP expression and activity in human cancers will provide the basis for the development of new strategies to target c-FLIP expression in human cancers.
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Affiliation(s)
- Simone Fulda
- Goethe-University Frankfurt, Institute for Experimental Cancer Research in Pediatrics, Komturstr. 3a, 60528 Frankfurt, Germany.
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68
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Mitotoxicity and bortezomib-induced chronic painful peripheral neuropathy. Exp Neurol 2012; 238:225-34. [DOI: 10.1016/j.expneurol.2012.08.023] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 08/15/2012] [Accepted: 08/21/2012] [Indexed: 01/29/2023]
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Cristofanon S, Fulda S. ABT-737 promotes tBid mitochondrial accumulation to enhance TRAIL-induced apoptosis in glioblastoma cells. Cell Death Dis 2012. [PMID: 23190604 PMCID: PMC3542599 DOI: 10.1038/cddis.2012.163] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
To search for novel strategies to enhance the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis pathways in glioblastoma, we used the B-cell lymphoma 2/Bcl2-like 2-inhibitor ABT-737. Here we report that ABT-737 and TRAIL cooperate to induce apoptosis in several glioblastoma cell lines in a highly synergistic manner (combination index <0.1). Interestingly, the concerted action of ABT-737 and TRAIL to trigger the accumulation of truncated Bid (tBid) at mitochondrial membranes is identified as a key underlying mechanism. ABT-737 and TRAIL cooperate to cleave BH3-interacting domain death agonist (Bid) into its active fragment tBid, leading to increased accumulation of tBid at mitochondrial membranes. Coinciding with tBid accumulation, the activation of Bcl2-associated X protein (Bax), loss of mitochondrial membrane potential, release of cytochrome-c and second mitochondria-derived activator of caspase (Smac) into the cytosol and caspase activation are strongly increased in cotreated cells. Of note, knockdown of Bid significantly decreases ABT-737- and TRAIL-mediated Bax activation and apoptosis. Also, caspase-3 silencing reduces ABT-737- and TRAIL-induced Bid cleavage and apoptosis, indicating that a caspase-3-driven, mitochondrial feedback loop contributes to Bid processing. Importantly, ABT-737 profoundly enhances TRAIL-triggered apoptosis in primary cultured glioblastoma cells derived from tumor material, underlining the clinical relevance. Also, ABT-737 acts in concert with TRAIL to suppress tumor growth in an in vivo glioblastoma model. In conclusion, the rational combination of ABT-737 and TRAIL cooperates to trigger tBid mitochondrial accumulation and apoptosis. This approach presents a promising strategy for targeting the apoptosis pathways in glioblastoma, which warrants further investigation.
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Affiliation(s)
- S Cristofanon
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany
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Quintavalle C, Donnarumma E, Iaboni M, Roscigno G, Garofalo M, Romano G, Fiore D, De Marinis P, Croce CM, Condorelli G. Effect of miR-21 and miR-30b/c on TRAIL-induced apoptosis in glioma cells. Oncogene 2012; 32:4001-8. [PMID: 22964638 DOI: 10.1038/onc.2012.410] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 06/13/2012] [Accepted: 07/23/2012] [Indexed: 12/27/2022]
Abstract
Glioblastoma is the most frequent brain tumor in adults and is the most lethal form of human cancer. Despite the improvements in treatments, survival of patients remains poor. To define novel pathways that regulate susceptibility to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in glioma, we have performed genome-wide expression profiling of microRNAs (miRs). We show that in TRAIL-resistant glioma cells, levels of different miRs are increased, and in particular, miR-30b/c and -21. We demonstrate that these miRs impair TRAIL-dependent apoptosis by inhibiting the expression of key functional proteins. T98G-sensitive cells treated with miR-21 or -30b/c become resistant to TRAIL. Furthermore, we demonstrate that miR-30b/c and miR-21 target respectively the 3' untranslated region of caspase-3 and TAp63 mRNAs, and that those proteins mediate some of the effects of miR-30 and -21 on TRAIL resistance, even in human glioblastoma primary cells and in lung cancer cells. In conclusion, we show that high expression levels of miR-21 and -30b/c are needed to maintain the TRAIL-resistant phenotype, thus making these miRs as promising therapeutic targets for TRAIL resistance in glioma.
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Affiliation(s)
- C Quintavalle
- Department of Cellular and Molecular Biology and Pathology, 'Federico II' University of Naples, Naples, Italy
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de Wilt LHAM, Kroon J, Jansen G, de Jong S, Peters GJ, Kruyt FAE. Bortezomib and TRAIL: a perfect match for apoptotic elimination of tumour cells? Crit Rev Oncol Hematol 2012; 85:363-72. [PMID: 22944363 DOI: 10.1016/j.critrevonc.2012.08.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/13/2012] [Accepted: 08/06/2012] [Indexed: 01/11/2023] Open
Abstract
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine that selectively eradicates tumour cells via specific cell surface receptors and is intensively explored for use as a novel anticancer approach. To enhance the efficacy of TRAIL receptor agonists the proteasome inhibitor bortezomib is one of the most potent sensitizers. Here we review the main mechanisms underlying bortezomib-dependent TRAIL sensitization, including stimulation of apoptosis by increasing expression of TRAIL receptors, reduction of cFLIP and enhancement of caspase 8 activation, and modulation of Bcl-2 family proteins and inhibitor of apoptosis proteins (IAPs). Concomitantly, pro-survival signals are suppressed such as elicited by NF-κB and Akt. The different preclinical tumour models explored with this combination, including primary tumour (stem) cells, stroma co-culture and mice models, are discussed, as well as possible hurdles for clinical activity. Collectively, anticipating a solid rationale for bortezomib-TRAIL combination and very promising preclinical results, its clinical activity remains to be demonstrated.
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Affiliation(s)
- L H A M de Wilt
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
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Cheng J, Tang W, Su Z, Guo J, Tong L, Wei Q. Calcineurin subunit B promotes TNF-alpha-induced apoptosis by binding to mitochondria and causing mitochondrial Ca2+ overload. Cancer Lett 2012; 321:169-78. [DOI: 10.1016/j.canlet.2012.01.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 01/31/2012] [Accepted: 01/31/2012] [Indexed: 11/26/2022]
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Fulda S, Rajalingam K, Dikic I. Ubiquitylation in immune disorders and cancer: from molecular mechanisms to therapeutic implications. EMBO Mol Med 2012; 4:545-56. [PMID: 22730341 PMCID: PMC3407942 DOI: 10.1002/emmm.201100707] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 04/30/2012] [Accepted: 05/11/2012] [Indexed: 01/01/2023] Open
Abstract
Conjugation of ubiquitin to proteins (ubiquitylation) has emerged to be one of the most crucial post-translational modifications controlling virtually all cellular processes. What was once regarded as a mere signal for protein degradation has turned out to be a major regulator of molecular signalling networks. Deregulation of ubiquitin signalling is closely associated with various human pathologies. Here, we summarize the current knowledge of ubiquitin signalling in immune deficiencies and cancer as well as the available therapeutic strategies targeting the ubiquitin system in combating these pathogenic conditions.
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Affiliation(s)
- Simone Fulda
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany
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Abstract
Brain tumors--particularly glioblastoma multiforme--pose an important public health problem in the United States. Despite surgical and medical advances, the prognosis for patients with malignant gliomas remains grim: current therapy is insufficient with nearly universal recurrence. A major reason for this failure is the difficulty of delivering therapeutic agents to the brain: better delivery approaches are needed to improve treatment. In this article, we summarize recent progress in drug delivery to the brain, with an emphasis on convection-enhanced delivery of nanocarriers. We examine the potential of new delivery methods to permit novel drug- and gene-based therapies that target brain cancer stem cells and discuss the use of nanomaterials for imaging of tumors and drug delivery.
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75
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Sung ES, Park KJ, Choi HJ, Kim CH, Kim YS. The proteasome inhibitor MG132 potentiates TRAIL receptor agonist-induced apoptosis by stabilizing tBid and Bik in human head and neck squamous cell carcinoma cells. Exp Cell Res 2012; 318:1564-76. [PMID: 22513214 DOI: 10.1016/j.yexcr.2012.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 03/26/2012] [Accepted: 04/02/2012] [Indexed: 11/19/2022]
Abstract
Head and neck squamous cell carcinoma (HNSCC) is often resistant to conventional chemotherapy and thus requires novel treatment regimens. Here, we investigated the effects of the proteasome inhibitor MG132 in combination with tumor necrosis factor-related apoptosis inducing ligand (TRAIL) or agonistic TRAIL receptor 1 (DR4)-specific monoclonal antibody, AY4, on sensitization of TRAIL- and AY4-resistant human HNSCC cell lines. Combination treatment of HNSCC cells synergistically induced apoptotic cell death accompanied by caspase-8, caspase-9, and caspase-3 activation and Bid cleavage into truncated Bid (tBid). Generation and accumulation of tBid through the cooperative action of MG132 with TRAIL or AY4 and Bik accumulation through MG132-mediated proteasome inhibition are critical to the synergistic apoptosis. In HNSCC cells, Bak was constrained by Mcl-1 and Bcl-X(L), but not by Bcl-2. Conversely, Bax did not interact with Mcl-1, Bcl-X(L), or Bcl-2. Importantly, tBid plays a major role in Bax activation, and Bik indirectly activates Bak by displacing it from Mcl-1 and Bcl-X(L), pointing to the synergistic mechanism of the combination treatment. In addition, knockdown of both Mcl-1 and Bcl-X(L) significantly sensitized HNSCC cells to TRAIL and AY4 as a single agent, suggesting that Bak constraint by Mcl-1 and Bcl-X(L) is an important resistance mechanism of TRAIL receptor-mediated apoptotic cell death. Our results provide a novel molecular mechanism for the potent synergy between MG132 proteasome inhibitor and TRAIL receptor agonists in HNSCC cells, suggesting that the combination of these agents may offer a new therapeutic strategy for HNSCC treatment.
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Affiliation(s)
- Eun-Sil Sung
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea
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Fulda S. Regulation of apoptosis pathways in cancer stem cells. Cancer Lett 2012; 338:168-73. [PMID: 22429999 DOI: 10.1016/j.canlet.2012.03.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 03/06/2012] [Accepted: 03/08/2012] [Indexed: 12/18/2022]
Abstract
Cancer stem cell are considered to represent a population within the bulk tumor that share many similarities to normal stem cells as far as their capacities to self-renew, differentiate, proliferate and to reconstitute the entire tumor upon serial transplantation are concerned. Since cancer stem cells have been shown to be critical for maintaining tumor growth and have been implicated in treatment resistance and tumor progression, they constitute relevant targets for therapeutic intervention. Indeed, it has been postulated that eradication of cancer stem cells will be pivotal in order to achieve long-term relapse-free survival. However, one of the hallmarks of cancer stem cells is their high resistance to undergo cell death including apoptosis in response to environmental cues or cytotoxic stimuli. Since activation of apoptosis programs in tumor cells underlies the antitumor activity of most currently used cancer therapeutics, it will be critical to develop strategies to overcome the intrinsic resistance to apoptosis of cancer stem cells. Thus, a better understanding of the molecular mechanisms that are responsible for the ability of cancer stem cells to evade apoptosis will likely open new avenues to target this critical pool of cells within the tumor in order to develop more efficient treatment options for patients suffering from cancer.
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Affiliation(s)
- Simone Fulda
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University Frankfurt, Komturstr. 3a, 60528 Frankfurt, Germany.
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