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Eke I, Leonhardt F, Storch K, Hehlgans S, Cordes N. The small molecule inhibitor QLT0267 Radiosensitizes squamous cell carcinoma cells of the head and neck. PLoS One 2009; 4:e6434. [PMID: 19649326 PMCID: PMC2713401 DOI: 10.1371/journal.pone.0006434] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Accepted: 06/30/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The constant increase of cancer cell resistance to radio- and chemotherapy hampers improvement of patient survival and requires novel targeting approaches. Integrin-Linked Kinase (ILK) has been postulated as potent druggable cancer target. On the basis of our previous findings clearly showing that ILK transduces antisurvival signals in cells exposed to ionizing radiation, this study evaluated the impact of the small molecule inhibitor QLT0267, reported as putative ILK inhibitor, on the cellular radiation survival response of human head and neck squamous cell carcinoma cells (hHNSCC). METHODOLOGY/PRINCIPAL FINDINGS Parental FaDu cells and FaDu cells stably transfected with a constitutively active ILK mutant (FaDu-IH) or empty vectors, UTSCC45 cells, ILK(floxed/floxed(fl/fl)) and ILK(-/-) mouse fibroblasts were used. Cells grew either two-dimensionally (2D) on or three-dimensionally (3D) in laminin-rich extracellular matrix. Cells were treated with QLT0267 alone or in combination with irradiation (X-rays, 0-6 Gy single dose). ILK knockdown was achieved by small interfering RNA transfection. ILK kinase activity, clonogenic survival, number of residual DNA double strand breaks (rDSB; gammaH2AX/53BP1 foci assay), cell cycle distribution, protein expression and phosphorylation (e.g. Akt, p44/42 mitogen-activated protein kinase (MAPK)) were measured. Data on ILK kinase activity and phosphorylation of Akt and p44/42 MAPK revealed a broad inhibitory spectrum of QLT0267 without specificity for ILK. QLT0267 significantly reduced basal cell survival and enhanced the radiosensitivity of FaDu and UTSCC45 cells in a time- and concentration-dependent manner. QLT0267 exerted differential, cell culture model-dependent effects with regard to radiogenic rDSB and accumulation of cells in the G2 cell cycle phase. Relative to corresponding controls, FaDu-IH and ILK(fl/fl) fibroblasts showed enhanced radiosensitivity, which failed to be antagonized by QLT0267. A knockdown of ILK revealed no change in clonogenic survival of the tested cell lines as compared to controls. CONCLUSIONS/SIGNIFICANCE Our data clearly show that the small molecule inhibitor QLT0267 has potent cytotoxic and radiosensitizing capability in hHNSCC cells. However, QLT0267 is not specific for ILK. Further in vitro and in vivo studies are necessary to clarify the potential of QLT0267 as a targeted therapeutic in the clinic.
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Beinke C, Van Beuningen D, Cordes N. Ionizing radiation modules of the expression and tyrosine phosphorylation of the focal adhesion‐associated proteins focal adhesion kinase (FAK) and its substrates p130cas and paxillin in A549 human lung carcinoma cellsin vitro. Int J Radiat Biol 2009; 79:721-31. [PMID: 14703945 DOI: 10.1080/09553000310001610231] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE Focal adhesion kinase (FAK) is involved in the regulation of many cellular processes, including cell survival and death, proliferation and migration. The same endpoints are influenced by ionizing radiation (IR). Therefore, study was performed to determine the effect of IR on the expression and phosphorylation of FAK and two of its substrates, p130cas and paxillin, in vitro. MATERIALS AND METHODS Exponentially growing A549 lung carcinoma cells were exposed to 6 Gy X-rays. Protein expression and the extent of tyrosine phosphorylation were investigated by immunoprecipitation experiments and Western blotting analysis using specific or unspecific phosphotyrosine antibodies. Immunofluorescence staining in combination with confocal laser scanning microscopy was done to localize the proteins within the cell. RESULTS Tyrosine phosphorylation, of Mr 110 000 150 000 and 65 000-75 000 protein bands, was induced within 30 min after exposure to IR. Three of these proteins were identified as FAK, p130cas and paxillin. IR induced phosphorylation of FAK (tyr397 and tyr925) but did not change FAK expression. Additionally, IR induced phosphorylation of paxillin (tyr31 and tyr181) within 30 min and an up-regulation of paxillin expression 2-6 h after exposure. Furthermore, a higher amount of phosphorylated p130cas was found in irradiated cells. Immunofluorescence staining demonstrated that in A549 cells, all three proteins colocalize at sites of focal adhesions at the cytoplasmic face of the cell membrane and to lamellopodia. CONCLUSIONS The data indicate that these focal adhesion-associated proteins are modulated by IR and thus are likely to play a role in the cellular response to IR. These proteins might represent attractive targets to modulate FAK-initiated signalling pathways, which may be involved in improved radioresistance and, furthermore, in important pathological phenomena such as tumour growth and metastatic phenotypes.
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Hehlgans S, Eke I, Cordes N. An essential role of integrin-linked kinase in the cellular radiosensitivity of normal fibroblasts during the process of cell adhesion and spreading. Int J Radiat Biol 2009; 83:769-79. [DOI: 10.1080/09553000701694327] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Sandfort V, Koch U, Cordes N. Cell adhesion-mediated radioresistance revisited. Int J Radiat Biol 2009; 83:727-32. [DOI: 10.1080/09553000701694335] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Haase M, Gmach CC, Eke I, Hehlgans S, Baretton GB, Cordes N. Expression of integrin-linked kinase is increased in differentiated cells. J Histochem Cytochem 2008; 56:819-29. [PMID: 18505933 DOI: 10.1369/jhc.2008.951095] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Integrin-linked kinase (ILK), a mediator of beta integrin signals, has emerged as a therapeutic target in malignant tumors. Because malignant transformation is accompanied by dedifferentiation, ILK expression was evaluated in diverse normal and tumor tissue samples with regard to tissue differentiation. In single sections and in a tissue microarray (323 tumor tissues, 181 normal tissues), immunohistochemistry was performed [ILK, Akt, phospho-Akt-S473, loricrin, transforming growth factor beta2 (TGFbeta2)], and staining intensities were semiquantitatively scored. Increased ILK expression was clearly associated with increased differentiation in normal gastrointestinal, neural, bone marrow, renal tissue, and in more differentiated areas of malignant tumors. ILK colocalized with its putative downstream target Akt and with loricrin or TGFbeta2. Our findings clearly show that elevated levels of ILK are associated with cellular differentiation in high turnover tissues but not generally with a malignant phenotype. Our study indicates that ILK is not a general molecular target for cancer therapy but rather an indicator of differentiation. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
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Eke I, Sandfort V, Storch K, Baumann M, Röper B, Cordes N. Pharmacological inhibition of EGFR tyrosine kinase affects ILK-mediated cellular radiosensitization in vitro. Int J Radiat Biol 2008; 83:793-802. [PMID: 18058367 DOI: 10.1080/09553000701727549] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE Integrin-linked kinase (ILK) mediates signals from beta integrins and links integrins to epidermal growth factor receptor (EGFR). Previous studies have identified an antisurvival effect of ILK in irradiated cells. The aim of this study was to evaluate the role of EGFR tyrosine kinase (tk) activity for ILK-mediated radiosensitization. MATERIALS AND METHODS Human FaDu squamous cell carcinoma (SCC) cells stably transfected with hyperactive ILK (ILK-hk) and ILK(fl/fl) and ILK(-/-) mouse fibroblasts were treated with the pharmacological EGFR-tk inhibitor BIBX1382BS without or in combination with single doses of X-rays. Clonogenic radiation survival, protein expression and phosphorylation (EGFR, v-akt murine thymoma viral oncogene homolog 1 (Akt), p42/44 mitogen-activated protein kinase), DNA-double strand break (DSB) repair measured by gammaH2AX foci, cell morphology and cell cycle distribution were examined. RESULTS Expression of ILK-hk or ILK(fl/fl) status resulted in significant radiosensitization relative to vector controls or ILK(-/-). Following BIBX1382BS, clonogenic survival of normal fibroblasts and vector controls remained unaffected while ILK-hk-related radiosensitization was significantly diminished. In contrast to BIBX1382BS, which did not affect DNA-DSB repair, ILK-hk-mediated radiosensitization was associated with reduced DNA-DSB repair. At 10 days after BIBX1382BS treatment, FaDu transfectants, in contrast to fibroblasts, showed reduced cell size, accumulation of G1 phase cells and reduced Akt-serine(S)473 phosphorylation. CONCLUSIONS Our findings confirm ILK as a cell type-independent antisurvival factor in irradiated cells, which actions in terms of radiosensitization critically depend on proper EGFR-tk activity.
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Hehlgans S, Eke I, Deuse Y, Cordes N. Integrin-linked kinase: dispensable for radiation survival of three-dimensionally cultured fibroblasts. Radiother Oncol 2007; 86:329-35. [PMID: 17905456 DOI: 10.1016/j.radonc.2007.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 08/07/2007] [Accepted: 09/06/2007] [Indexed: 11/20/2022]
Abstract
PURPOSE Cancer treatment by conventional radiotherapy is limited by normal tissue side-effects. Fibroblasts as "non-target" stromal cell type are considered as strong promoter of tumor growth and for developing a therapy resistant phenotype. Regarding application of novel molecular therapeutics combined with radiotherapy, evaluation of a specific targeted molecule in both tumor and normal cells is mandatory for efficacy and tolerability assessment. Previous work showed integrin-linked kinase (ILK), a mediator of beta-integrin signals and putative phosphorylator of AKT, as potent anti-survival regulator in human cancer cell lines. MATERIALS AND METHODS To evaluate the role of ILK in normal fibroblast survival, ILK-wild-type (ILK(fl/fl)), ILK(-/-) and ILK(N-terminal) and ILK(C-terminal) domain expressing fibroblasts were irradiated with X-rays on different substrata or in three-dimensional laminin-rich extracellular matrix (lrECM). RESULTS On control substrata, ILK-deficient and ILK-mutant fibroblasts showed significant increase in radiation survival relative to ILK-wild-type cells. This effect was compensated by growth on ECM proteins and in 3D lrECM. ILK regulated AKT activity in a phosphatidylinositol-3 kinase (PI3K)-dependent manner. Upon PI3K inhibition, only ILK-wild-type fibroblasts showed significant radiosensitization. CONCLUSIONS These findings obtained in 3D cell cultures suggest ILK to be dispensable for the radiation survival response of normal fibroblasts. However, targeting the PI3K/AKT signaling axis pharmacologically might be critical for survival of normal fibroblasts exposed to ionizing radiation.
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Cordes N, Frick S, Brunner TB, Pilarsky C, Grützmann R, Sipos B, Klöppel G, McKenna WG, Bernhard EJ. Human pancreatic tumor cells are sensitized to ionizing radiation by knockdown of caveolin-1. Oncogene 2007; 26:6851-62. [PMID: 17471232 DOI: 10.1038/sj.onc.1210498] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Caveolin-1 (Cav-1) is an integral transmembrane protein and a critical component in interactions of integrin receptors with cytoskeleton-associated and signaling molecules. Since integrin-mediated cell adhesion generates signals conferring radiation resistance, we examined the effects of small interfering RNA-mediated knockdown of Cav-1 alone or in combination with beta1-integrin or focal adhesion kinase (FAK) on radiation survival and proliferation of pancreatic carcinoma cell lines. Irradiation induced Cav-1 expression in PATU8902, MiaPaCa2 and Panc1 cell lines. The cell lines showed significant radiosensitization after knockdown of Cav-1, beta1-integrin or FAK and cholesterol depletion by beta-cyclodextrin relative to nonspecific controls. Under knockdown conditions, proliferation of non-irradiated and irradiated cells was significantly attenuated relative to controls. These findings correlated with changes in expression or phosphorylation of Akt, glycogen synthase kinase 3beta, Paxillin, Src, c-Jun N-terminal kinase and mitogen-activated protein kinase. Analysis of DNA microarray data revealed a Cav-1 overexpression in a subset of pancreatic ductal adenocarcinoma samples. The data presented show, for the first time, that disruption of interactions of Cav-1 with beta1-integrin or FAK affects radiation survival and proliferation of pancreatic carcinoma cells and suggest that Cav-1 is critical to these processes. These results indicate that strategies targeting Cav-1 may be useful as an approach to improve conventional therapies, including radiotherapy, for pancreatic cancer.
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Estrugo D, Fischer A, Hess F, Scherthan H, Belka C, Cordes N. Ligand bound beta1 integrins inhibit procaspase-8 for mediating cell adhesion-mediated drug and radiation resistance in human leukemia cells. PLoS One 2007; 2:e269. [PMID: 17342203 PMCID: PMC1800908 DOI: 10.1371/journal.pone.0000269] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Accepted: 02/12/2007] [Indexed: 11/18/2022] Open
Abstract
Background Chemo- and radiotherapeutic responses of leukemia cells are modified by integrin-mediated adhesion to extracellular matrix. To further characterize the molecular mechanisms by which β1 integrins confer radiation and chemoresistance, HL60 human acute promyelocytic leukemia cells stably transfected with β1 integrin and A3 Jurkat T-lymphoma cells deficient for Fas-associated death domain protein or procaspase-8 were examined. Methodology/Principal Findings Upon exposure to X-rays, Ara-C or FasL, suspension and adhesion (fibronectin (FN), laminin, collagen-1; 5–100 µg/cm2 coating concentration) cultures were processed for measurement of apoptosis, mitochondrial transmembrane potential (MTP), caspase activation, and protein analysis. Overexpression of β1 integrins enhanced the cellular sensitivity to X-rays and Ara-C, which was counteracted by increasing concentrations of matrix proteins in association with reduced caspase-3 and -8 activation and MTP breakdown. Usage of stimulatory or inhibitory anti β1 integrin antibodies, pharmacological caspase or phosphatidylinositol-3 kinase (PI3K) inhibitors, coprecipitation experiments and siRNA-mediated β1 integrin silencing provided further data showing an interaction between FN-ligated β1 integrin and PI3K/Akt for inhibiting procaspase-8 cleavage. Conclusions/Significance The presented data suggest that the ligand status of β1 integrins is critical for their antiapoptotic effect in leukemia cells treated with Ara-C, FasL or ionizing radiation. The antiapoptotic actions involve formation of a β1 integrin/Akt complex, which signals to prevent procaspase-8-mediated induction of apoptosis in a PI3K-dependent manner. Antagonizing agents targeting β1 integrin and PI3K/Akt signaling in conjunction with conventional therapies might effectively reduce radiation- and drug-resistant tumor populations and treatment failure in hematological malignancies.
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Hehlgans S, Haase M, Cordes N. Signalling via integrins: implications for cell survival and anticancer strategies. Biochim Biophys Acta Rev Cancer 2006; 1775:163-80. [PMID: 17084981 DOI: 10.1016/j.bbcan.2006.09.001] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 09/26/2006] [Accepted: 09/28/2006] [Indexed: 01/13/2023]
Abstract
Integrin-associated signalling renders cells more resistant to genotoxic anti-cancer agents like ionizing radiation and chemotherapeutic substances, a phenomenon termed cell adhesion-mediated radioresistance/drug resistance (CAM-RR, CAM-DR). Integrins are heterodimeric cell-surface molecules that on one side link the actin cytoskeleton to the cell membrane and on the other side mediate cell-matrix interactions. In addition to their structural functions, integrins mediate signalling from the extracellular space into the cell through integrin-associated signalling and adaptor molecules such as FAK (focal adhesion kinase), ILK (integrin-linked kinase), PINCH (particularly interesting new cysteine-histidine rich protein) and Nck2 (non-catalytic (region of) tyrosine kinase adaptor protein 2). Via these molecules, integrin signalling tightly and cooperatively interacts with receptor tyrosine kinase signalling to regulate survival, proliferation and cell shape as well as polarity, adhesion, migration and differentiation. In tumour cells of diverse origin like breast, colon or skin, the function and regulation of these molecules is partly disturbed and thus might contribute to the malignant phenotype and pre-existent and acquired multidrug resistance. These issues as well as a variety of therapeutic options envisioned to influence tumour cell growth, metastasis and resistance, including kinase inhibitors, anti-integrin antibodies or RNA interference, will be summarized and discussed in this review.
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Cordes N. Integrin-mediated cell–matrix interactions for prosurvival and antiapoptotic signaling after genotoxic injury. Cancer Lett 2006; 242:11-9. [PMID: 16448744 DOI: 10.1016/j.canlet.2005.12.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 11/22/2005] [Accepted: 12/04/2005] [Indexed: 01/10/2023]
Abstract
Interactions of cells with their microenvironment modify the cellular sensitivity of normal and tumor cells for radiation- and drug-induced genotoxic injury. The preexistent or acquired cellular resistance against such agents aggravates anticancer therapies and, therefore, complicates the recovery of patients. Recently, integrin-mediated adhesion was shown to improve cell survival of both normal and cancer cells following DNA damage. Here, I will discuss the role of integrins and integrin-mediated signaling cascades in the survival or death response upon genotoxic stress. Detailed knowledge of the responsible molecular processes might provide implications for putative therapies targeting integrins or integrin-associated molecules to achieve an optimization of anticancer treatments.
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Hess F, Estrugo D, Fischer A, Belka C, Cordes N. Integrin-linked kinase interacts with caspase-9 and -8 in an adhesion-dependent manner for promoting radiation-induced apoptosis in human leukemia cells. Oncogene 2006; 26:1372-84. [PMID: 16936772 DOI: 10.1038/sj.onc.1209947] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Integrin-mediated adhesion of leukemia cells to extracellular matrix proteins reduces apoptosis following radiation-induced genotoxic injury. To evaluate the role of integrin-linked kinase (ILK) in this process, HL60 human acute promyelocytic leukemia cells were stably transfected with ILK wild-type or kinase-hyperactive overexpression vectors. Suspension or fibronectin (FN) adhesion cultures were irradiated with X-rays and processed for measurement of apoptosis, mitochondrial transmembrane potential and caspase activation. Adhesion to FN pronouncedly reduced radiation-induced apoptosis of HL60 cells and vector controls. Intriguingly, overexpressed ILK enhanced apoptosis after irradiation by combined activation of caspase-3 through caspase-8 and -9 in irradiated FN cultures. Irradiation of ILK suspension cultures lacked caspase-8 activation, but showed serial cleavage of caspase-9, -3 and poly (ADP-ribose) polymerase. These findings further characterize the cell death-promoting function of ILK in DNA-damaged cells. Moreover, ILK might represent a potential therapeutic target for innovative chemo- and radiooncological approaches in hematological malignancies.
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Eke I, Sandfort V, Mischkus A, Baumann M, Cordes N. Antiproliferative effects of EGFR tyrosine kinase inhibition and radiation-induced genotoxic injury are attenuated by adhesion to fibronectin. Radiother Oncol 2006; 80:178-84. [PMID: 16891020 DOI: 10.1016/j.radonc.2006.07.028] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 07/19/2006] [Accepted: 07/20/2006] [Indexed: 01/18/2023]
Abstract
BACKGROUND AND PURPOSE Integrin-linked kinase (ILK) functions in cooperative integrin-growth factor receptor-mediated signaling to control cell survival and proliferation. The effect of tyrosine kinase (tk) inhibition of the epidermal growth factor receptor (EGFR) on radiation survival and growth was evaluated in human FaDu squamous cell carcinoma cells expressing different forms of ILK. MATERIAL AND METHODS ILK-wild-type (wk) and -hyperactive kinase (hk) transfected cells were grown on fibronectin (Fn) under serum presence or depletion, irradiated (0-6Gy) and/or treated with the EGFR-tk inhibitor BIBX1382BS. RESULTS ILK-wk and -hk transfectants showed significant radiosensitization compared to vector control cells. Antisurvival and antiproliferative effects of EGFR-tk inhibition plus/minus irradiation were counteracted by adhesion to Fn relative to the control substratum, poly-L-lysine. Similar to vector controls, ILK transfectants exhibited a strong decrease in cell proliferation but no enhanced radiation sensitivity after EGFR-tk inhibition. This decrease was accompanied by changes in cyclin D1 and phosphorylated MAPK persisting to day 10 following transient drug exposure. CONCLUSIONS Our data demonstrate a prosurvival role of adhesion and an antisurvival role of ILK upon irradiation. Inhibition of EGFR-tk using BIBX1382BS does not affect the intrinsic cellular radiosensitivity of cells grown on fibronectin. Thus, simultaneous targeting of adhesion and growth factor receptor-mediated signaling might potently improve anticancer strategies.
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Cordes N, Seidler J, Durzok R, Geinitz H, Brakebusch C. beta1-integrin-mediated signaling essentially contributes to cell survival after radiation-induced genotoxic injury. Oncogene 2006; 25:1378-90. [PMID: 16247454 DOI: 10.1038/sj.onc.1209164] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Integrin-mediated adhesion to extracellular matrix proteins confers resistance to radiation- or drug-induced genotoxic injury. To analyse the underlying mechanisms specific for beta1-integrins, wild-type beta1A-integrin-expressing GD25beta1A cells were compared to GD25beta1B cells, which express signaling-incompetent beta1B variants. Cells grown on fibronectin, collagen-III, beta1-integrin-IgG or poly-l-lysine were exposed to 0-6 Gy X-rays in presence or depletion of growth factors and phosphatidylinositol-3 kinase (PI3K) inhibitors (LY294002, wortmannin). In order to test the relevance of these findings in tumor cells, human A-172 glioma cells were examined under the same conditions after siRNA-mediated silencing of beta1-integrins. We found that beta1A-integrin-mediated adhesion to fibronectin, collagen-III or beta1-IgG was essential for cell survival after radiation-induced genotoxic injury. Mediated by PI3K, pro-survival beta1A-integrin/Akt signaling was critically involved in this process. Additionally, the beta1-integrin downstream targets p130Cas and paxillin-impaired survival-regulating PI3K-dependent JNK. In A-172 glioma cells, beta1-integrin knockdown and PI3K inhibition confirmed the central role of beta1-integrins in Akt- and p130Cas/paxillin-mediated prosurvival signaling. These findings suggest beta1-integrins as critical regulators of cell survival after radiation-induced genotoxic injury. Elucidation of the molecular circuitry of prosurvival beta1-integrin-mediated signaling in tumor cells may promote the development of innovative molecular-targeted therapeutic antitumor strategies.
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Hess F, Estrugo D, Fischer A, Cordes N. 113 β1-integrin or integrin-linked kinase overexpression promotes radiation-induced apoptosis in human HL60 leukemia cells. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80592-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Eke I, Mischkus A, Baumann M, Cordes N. 181 Cell adhesion to fibronectin strongly attenuates pharmacological egf-receptor tyrosine kinase inhibition in an integrin-linked kinase-independent manner. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80659-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Haase M, Tschuck D, Cordes N. 130 Differential expression of integrin-associated proteins in mast cells of radiation-damaged tissue. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80609-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Cordes N, Brakebusch C. 182 β1-integrins in cell adhesion-mediated radioresistance: First emerging insights. Radiother Oncol 2006. [DOI: 10.1016/s0167-8140(06)80660-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Seidler J, Durzok R, Brakebusch C, Cordes N. Interactions of the integrin subunit beta1A with protein kinase B/Akt, p130Cas and paxillin contribute to regulation of radiation survival. Radiother Oncol 2006; 76:129-34. [PMID: 16024122 DOI: 10.1016/j.radonc.2005.06.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 05/13/2005] [Accepted: 06/19/2005] [Indexed: 11/25/2022]
Abstract
BACKGROUND AND PURPOSE Cell adhesion-mediated radioresistance is a common phenomenon particularly relevant in tumor cells, which might hamper anticancer therapies. To analyze the role of adhesion-mediating beta1-integrins, stably transfected functional beta1A-integrin-expressing GD25beta1A and GD25beta1B cells, which express mutant beta1B-integrins, were compared in terms of radiation survival and beta1-integrin signaling. MATERIALS AND METHODS Cells grown on fibronectin, collagen-III, laminin, vitronectin, anti-beta1-integrin-IgG (beta1-IgG) or poly-l-lysine were irradiated with 0-6Gy in presence or absence of growth factors or inhibitors for phosphatidylinositol-3 kinase (PI3K), i.e. Ly294002 and wortmannin. In addition to colony formation, protein kinase B/Akt (PKB/Akt) kinase activity, focal adhesion kinase (FAK), p130Cas, paxillin and c-Jun N2-terminal kinase (JNK) expression and phosphorylation were analyzed by Western blot technique. RESULTS Adhesion of GD25beta1A cells to extracellular matrix proteins or beta1-IgG resulted in growth factor-independent radiation survival. In contrast, serum starved GD25beta1B cells showed a significant (P<0.01) reduction in radiation survival on all substrates. PI3K inhibition moderately or strongly radiosensitized GD25beta1A or GD25beta1B cells, respectively. The pro-survival effects detected in serum starved GD25beta1A cells were due to direct, PI3K-mediated stimulation of PKB/Akt activity by beta1-integrins and induced p130Cas and paxillin phosphorylation. Phosphorylated p130Cas and paxillin subsequently prevented activation of cell death-regulating JNK. CONCLUSIONS The data show that beta1-integrin-mediated signaling through the cytoplasmic integrin domains is critical for efficient pro-survival regulation after irradiation. Profound knowledge of the underlying mechanisms of integrin-mediated cellular radioresistance could foster the design of new molecular-targeted anticancer therapies.
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Habermehl D, Kammerer B, Handrick R, Eldh T, Gruber C, Cordes N, Daniel PT, Plasswilm L, Bamberg M, Belka C, Jendrossek V. Proapoptotic activity of Ukrain is based on Chelidonium majus L. alkaloids and mediated via a mitochondrial death pathway. BMC Cancer 2006; 6:14. [PMID: 16417634 PMCID: PMC1379651 DOI: 10.1186/1471-2407-6-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Accepted: 01/17/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The anticancer drug Ukrain (NSC-631570) which has been specified by the manufacturer as semisynthetic derivative of the Chelidonium majus L. alkaloid chelidonine and the alkylans thiotepa was reported to exert selective cytotoxic effects on human tumour cell lines in vitro. Few clinical trials suggest beneficial effects in the treatment of human cancer. Aim of the present study was to elucidate the importance of apoptosis induction for the antineoplastic activity of Ukrain, to define the molecular mechanism of its cytotoxic effects and to identify its active constituents by mass spectrometry. METHODS Apoptosis induction was analysed in a Jurkat T-lymphoma cell model by fluorescence microscopy (chromatin condensation and nuclear fragmentation), flow cytometry (cellular shrinkage, depolarisation of the mitochondrial membrane potential, caspase-activation) and Western blot analysis (caspase-activation). Composition of Ukrain was analysed by mass spectrometry and LC-MS coupling. RESULTS Ukrain turned out to be a potent inducer of apoptosis. Mechanistic analyses revealed that Ukrain induced depolarisation of the mitochondrial membrane potential and activation of caspases. Lack of caspase-8, expression of cFLIP-L and resistance to death receptor ligand-induced apoptosis failed to inhibit Ukrain-induced apoptosis while lack of FADD caused a delay but not abrogation of Ukrain-induced apoptosis pointing to a death receptor independent signalling pathway. In contrast, the broad spectrum caspase-inhibitor zVAD-fmk blocked Ukrain-induced cell death. Moreover, over-expression of Bcl-2 or Bcl-xL and expression of dominant negative caspase-9 partially reduced Ukrain-induced apoptosis pointing to Bcl-2 controlled mitochondrial signalling events. However, mass spectrometric analysis of Ukrain failed to detect the suggested trimeric chelidonine thiophosphortriamide or putative dimeric or monomeric chelidonine thiophosphortriamide intermediates from chemical synthesis. Instead, the Chelidonium majus L. alkaloids chelidonine, sanguinarine, chelerythrine, protopine and allocryptopine were identified as major components of Ukrain. Apart from sanguinarine and chelerythrine, chelidonine turned out to be a potent inducer of apoptosis triggering cell death at concentrations of 0.001 mM, while protopine and allocryptopine were less effective. Similar to Ukrain, apoptosis signalling of chelidonine involved Bcl-2 controlled mitochondrial alterations and caspase-activation. CONCLUSION The potent proapoptotic effects of Ukrain are not due to the suggested "Ukrain-molecule" but to the cytotoxic efficacy of Chelidonium majus L. alkaloids including chelidonine.
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Cordes N, Meineke V. Modification of the cellular radiation survival and proliferation response by cell-matrix interactions: implications for integrin targeting in therapeutic approaches for radiation accident patients. Br J Radiol 2005. [DOI: 10.1259/bjr/55705431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Cordes N. Overexpression of Hyperactive Integrin-Linked Kinase Leads to Increased Cellular Radiosensitivity. Cancer Res 2004; 64:5683-92. [PMID: 15313908 DOI: 10.1158/0008-5472.can-04-1056] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Integrin-linked kinase (ILK), bound to the cytoplasmic tails of integrin beta1, beta2, and beta3, is thought to signal through AKT and glycogen synthase kinase-3beta (GSK-3beta) for survival and proliferation regulation. To determine the role of ILK in the cellular radiation response, stably transfected A549 lung cancer cells overexpressing either wild-type (ILK-wk) or hyperactive ILK (ILK-hk) were studied for survival, signaling, proliferation, and examined in immunofluorescence and adhesion assays. Strong radiosensitization was observed in ILK-hk in contrast to ILK-wk mutants and empty vector controls. ILK small interfering RNA transfections showed radioresistance similar to irradiation on fibronectin. AKT, GSK-3beta-cyclin D1, mitogen-activated protein kinase kinase 1/2-mitogen-activated protein kinase, and c-Jun NH2-terminal kinase signaling was dysregulated in irradiated ILK-hk mutants. Immunofluorescence stainings of ILK-hk cells indicated disturbed ILK and paxillin membrane localization with concomitant decrease in focal adhesions. Profound ILK-hk-dependent changes in morphology were characterized by spindle-like cell shape, cell size reduction, increased cell protrusions, strong formation of membranous f-actin rings, and significantly reduced adhesion to matrix proteins. Additionally, ILK-wk and ILK-hk overexpression impaired beta1-integrin clustering and protein Tyr-phosphorylation. Taken together, the data provide evidence that ILK signaling modulates the cellular radiation response involving diverse signaling pathways and through changes in f-actin-based processes such as focal adhesion formation, cell adhesion, and spreading. Identification of ILK and its signaling partners as potential targets for tumor radiosensitization might promote innovative anticancer strategies by providing insight into the mechanism of cell adhesion-mediated radioresistance, oncogenic transformation, and tumor growth and spread.
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Cordes N, Beinke C, Plasswilm L, van Beuningen D. Irradiation and various cytotoxic drugs enhance tyrosine phosphorylation and beta(1)-integrin clustering in human A549 lung cancer cells in a substratum-dependent manner in vitro. Strahlenther Onkol 2004; 180:157-64. [PMID: 14991204 DOI: 10.1007/s00066-004-1144-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2003] [Accepted: 08/06/2003] [Indexed: 11/25/2022]
Abstract
BACKGROUND AND PURPOSE Interactions of cells with a substratum, especially extracellular matrix proteins, initiate clustering of integrin receptors in the cell membrane. This process represents the initial step for the activation of signaling pathways regulating survival, proliferation, differentiation, adhesion, and migration, and could, furthermore, be important for cellular resistance mediating mechanisms against radiation or cytotoxic drugs. The lack of data elucidating the impact of irradiation or cytotoxic drugs on this important phenomenon led to this study on human A549 lung cancer cells in vitro. MATERIAL AND METHODS The human lung carcinoma cell line A549 grown on polystyrene or fibronectin (FN) was irradiated with 0-8 Gy or treated with cisplatin (0.1-50 microM), paclitaxel (0.1-50 nM), or mitomycin (0.1-50 microM). Colony formation assays, immunofluorescence staining in combination with activation of integrin clustering using anti-beta(1)-integrin antibodies (K20), and Western blotting for tyrosine phosphorylation under treatment of cells with the IC(50) for irradiation (2 Gy; IC(50) = 2.2 Gy), cisplatin (2 microM), paclitaxel (5 nM), or mitomycin (7 microM) were performed. RESULTS Attachment of cells to FN resulted in a significantly reduced radio- and chemosensitivity compared to polystyrene. The clustering of beta(1)-integrins examined by immunofluorescence staining was only stimulated by irradiation, cisplatin, paclitaxel, or mitomycin in case of cell attachment to FN. By contrast, tyrosine phosphorylation, as one of the major events following beta(1)-integrin clustering, showed a 3.7-fold, FN-related enhancement, and treatment of cells with the IC(50) of radiation, cisplatin, paclitaxel, or mitomycin showed a substratum-dependent induction. CONCLUSION For the first time, a strong influence of irradiation and a variety of cytotoxic drugs on the clustering of beta(1)-integrins could be shown. This event is a prerequisite for tyrosine phosphorylation and, thus, the activation of cellular mechanisms regulating survival, proliferation, and adhesion. These data are not only important for the understanding of cellular resistance against cytotoxic agents but, furthermore, for tumor progression, anchorage-independent cell growth, and, possibly, the optimization of radiochemotherapeutic strategies.
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