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Cell shape and architecture are determined by cell-extracellular matrix interactions and have profound effects on cellular behavior, chromatin condensation, and tumor cell resistance to radiotherapy and chemotherapy. To evaluate the role of chromatin condensation for radiation cell survival, tumor cells grown in three-dimensional (3D) cell cultures as xenografts and monolayer cell cultures were compared. Here, we show that increased levels of heterochromatin in 3D cell cultures characterized by histone H3 deacetylation and induced heterochromatin protein 1α expression result in increased radiation survival and reduced numbers of DNA double strand breaks (DSB) and lethal chromosome aberrations. Intriguingly, euchromatin to heterochromatin–associated DSBs were equally distributed in irradiated 3D cell cultures and xenograft tumors, whereas irradiated monolayer cultures showed a 2:1 euchromatin to heterochromatin DSB distribution. Depletion of histone deacetylase (HDAC) 1/2/4 or application of the class I/II pharmacologic HDAC inhibitor LBH589 induced moderate or strong chromatin decondensation, respectively, which was translated into cell line–dependent radiosensitization and, in case of LBH589, into an increased number of DSBs. Neither growth conditions nor HDAC modifications significantly affected the radiation-induced phosphorylation of the important DNA repair protein ataxia telangiectasia mutated. Our data show an interrelation between cell morphology and cellular radiosensitivity essentially based on chromatin organization. Understanding the molecular mechanisms by which chromatin structure influences the processing of radiation-induced DNA lesions is of high relevance for normal tissue protection and optimization of cancer therapy. Cancer Res; 70(10); 3925–34. ©2010 AACR.

PDF file, 606K, Methods, Figures, Figure legends, Tables Fig. S1. A, EGFR protein expression in A549 and H1299 cells evaluated by Western blot. Fig. S2. A, A549 cells were cultured in the presence (+FCS) or absence (-FCS) of FCS and B, additionally treated with Cetuximab (5 microg/ml) for 24 h or 48 h. Fig. S3. Confocal fluorescence images of EGFR localization Fig. S4. Western blot analysis of A549 cells treated with Cetuximab Fig. S5. Immunofluorescence staining of CREB and phosphorylated CREB in A549 cells 48 h after treatment with Cetuximab Fig. S6. Promotor activity Table S1. List of Data sets Table S2. List of specific primers and probes.

Supplementary Methods, Figures 1-15, Tables 1-9 from Three-Dimensional Cell Growth Confers Radioresistance by Chromatin Density Modification

Acquired polyneuropathies (PN) are rare in childhood and adolescent. We report on a 15-year-old male patient who presented with progressive gait instability, ataxia, neuropathic pain, distal muscle weakness and progressive loss of ambulation. Nerve conduction studies (NCS) revealed a progressive demyelinating sensorimotor polyneuropathy predominantly of the lower limbs. Cerebrospinal fluid (CSF) analyses revealed a cytoalbuminologic dissociation. Extensive diagnostic workup for autoantibodies and inflammatory markers was inconclusive. Corticosteroids and intravenous immunoglobulins did not affect. Cranial MRI revealed leptomeningeal enhancement of the cerebellum and the brainstem. Brain biopsy of the cerebellar lesions revealed an unclassifiable sarcoma. The patient was treated according to the CWS guidance study resulting in a decrease in enhanced lesion size. After two years NCS still revealed a demyelinating sensorimotor PN. This case report describes for the first time the clinical course of a chronic PN, putative paraneoplastic, associated with isolated unclassifiable CNS-sarcoma in an adolescent patient. Paraneoplastic pathogenesis should be considered in an unusual sequence of subacute progressive neurological symptoms even in children and adolescents.

Acute necrotizing encephalopathy (ANE) is a rare disease presenting with rapidly progressing encephalopathy. It usually occurs in otherwise healthy children after common viral infections. The hallmarks of ANE are the neuroradiological findings of multiple symmetric lesions in the thalami, midbrain, pons and brainstem. Most cases are sporadic and non recurrent. However, recurrent or familial forms of ANE due to mutations in RANBP2 gene have been reported. It has been suggested to give these cases the term ANE1. We report the clinical course in two male infants (P1, P2) with ANE1 and a variable clinical course and outcome. One patient is heterozygous for the most common RANBP2 missense mutation p.Thr585Met. In the other patient we observed a novel de novo missense mutation p.Trp681Cys in the RANBP2 gene causing recurrent ANE. Clinical and radiological features are presented and differential diagnoses are discussed. This report adds to the current knowledge of the phenotype in ANE, caused by mutations in RANBP2 gene.

Purpose: To evaluate matrix metalloproteinase (MMP) activity and invasion after ionizing radiation (IR) exposure and to determine whether MMP could be epigenetically modulated by histone deacetylase (HDAC) inhibition.Material and methods: Two human breast cancer cell lines (MDA-MB-231 and MCF-7) were cultured in monolayer (2D) and in laminin-rich extracellular matrix (3D). Invasion capability, collagenolytic and gelatinolytic activity, MMP and TIMP protein and mRNA expression and clonogenic survival were analyzed after IR exposure, with and without a HDAC inhibition treatment [1.5 mM valproic acid (VA) or 1 μM trichostatin-A (TSA)].Results: IR exposure resulted in cell line-dependent stimulation of invasion capacity. In contrast to MCF-7 cells, irradiated MDA-MB-231 showed significantly enhanced mRNA expression of mmp-1, mmp-3 and mmp-13 and of their regulators timp-1 and timp-2 relative to unirradiated controls. This translated into increased collagenolytic and gelatinolytic activity and could be reduced after valproic acid (VA) treatment. Additionally, VA also mitigated IR-enhanced mmp and timp mRNA expression as well as IR-increased invasion capability. Finally, our data confirm the radiosensitizing effect of VA.Conclusion: These results suggest that IR cell line-dependently induces upregulation of MMP mRNA expression, which appears to be mechanistically linked to a higher invasion capability that is modifiable by HDAC inhibition.

Inhibition of histone deacetylases (HDACs) has preclinically and clinically shown promise to overcome radio- and chemoresistance of tumor cells. NDACI054 is a novel HDAC inhibitor, which has been evaluated here for its effects on cell survival and radiosensitization of human tumor cell lines from different origins cultured under more physiological three-dimensional (3D), extracellular matrix (ECM)-based conditions.A549 lung, DLD-1 colorectal, MiaPaCa2 pancreatic and UT-SCC15 head and neck squamous cell carcinoma cells were treated with increasing NDACI054 concentrations (0-50 nM, 24 h) either alone or in combination with X-rays (single dose, 0-6 Gy). Subsequently, 3D clonogenic cell survival, HDAC activity, histone H3 acetylation, apoptosis, residual DNA damage (γH2AX/p53BP1 foci assay 24h post irradiation) and phosphorylation kinetics of Ataxia telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), Caspase-3 and Poly(ADP-ribose)-Polymerase 1 (PARP 1) cleavage were analyzed.NDACI054 potently decreased HDAC activity with concomitant increase in acetyl-histone H3 levels, mediated significant cytotoxicity and radiosensitization. These effects were accompanied by a significant increase of residual γH2AX/p53BP1-positive foci, slightly elevated levels of Caspase-3 and PARP 1 cleavage but no induction of apoptosis.Our data show potent antisurvival and radiosensitizing effects of the novel HDAC inhibitor NDACI054 encouraging further preclinical examinations on this compound for future clinical use.

PURPOSE: Cyclin-dependent kinase 2 (CDK2) is critically involved in cell cycling and has been proposed as a potential cancer target. It remains largely elusive whether CDK2 targeting alters the tumor cell radiosensitivity. MATERIALS AND METHODS: CDK2(-/-) and wild type (WT) mouse embryonic fibroblasts (MEF) as well as six human head and neck squamous cell carcinoma (HNSCC) cell lines (SAS, FaDu, Cal-33, HSC-4, UTSCC-5, UTSCC-8) were used. Upon CDK2 knockdown using small interfering technology, colony formation, DNA double-strand breaks (DSB), cell cycle distribution and expression and phosphorylation of major proteins regulating cell cycle and DNA damage repair were examined. RESULTS: CDK2(-/-) MEF and CDK2 HNSCC knockdown cell cultures were more radiosensitive than the corresponding controls. Repair of DSB was attenuated under CDK2 knockout or knockdown. In contrast to data in MEF, combined CDK2 knockdown with irradiation showed no cell cycling alterations in SAS and FaDu cultures. Importantly, CDK2 knockdown failed to radiosensitize SAS and FaDu when cultured in a more physiological three-dimensional (3D) extracellular matrix environment. CONCLUSIONS: Our findings suggest that targeting of CDK2 radiosensitizes HNSCC cells growing as monolayer. Additional studies performed under more physiological conditions are warranted to clarify the potential of CDK2 as target in radiotherapy.

Radiation and chemotherapy are the main pillars of the current multimodal treatment concept for cancer patients. However, tumor recurrences and resistances still hamper treatment success regardless of advances in radiation beam application, particle radiotherapy, and optimized chemotherapeutics. To specifically intervene at key recurrence- and resistance-promoting molecular processes, the development of potent and specific molecular-targeted agents is demanded for an efficient, safe, and simultaneous integration into current standard of care regimens. Potential targets for such an approach are integrins conferring structural and biochemical communication between cells and their microenvironment. Integrin binding to extracellular matrix activates intracellular signaling for regulating essential cellular functions such as survival, proliferation, differentiation, adhesion, and cell motility. Tumor-associated characteristics such as invasion, metastasis, and radiochemoresistance also highly depend on integrin function. Owing to their dual functionality and their overexpression in the majority of human malignancies, integrins present ideal and accessible targets for cancer therapy. In the following chapter, the current knowledge on aspects of the tumor microenvironment, the molecular regulation of integrin-dependent radiochemoresistance and current approaches to integrin targeting are summarized.

Cancer resistance to therapy presents an ongoing and unsolved obstacle, which has clear impact on patient's survival. In order to address this problem, novelin vitromodels have been established and are currently developed that enable data generation in a more physiological context. For example, extracellular-matrix- (ECM-) based scaffolds lead to the identification of integrins and integrin-associated signaling molecules as key promoters of cancer cell resistance to radio- and chemotherapy as well as modern molecular agents. In this paper, we discuss the dynamic nature of the interplay between ECM, integrins, cytoskeleton, nuclear matrix, and chromatin organization and how this affects the response of tumor cells to various kinds of cytotoxic anticancer agents.

Cyclin-dependent kinase 9 (CDK9), mainly involved in regulation of transcription, has recently been shown to impact on cell cycling and DNA repair. Despite the fact that CDK9 has been proposed as potential cancer target, it remains largely elusive whether CDK9 targeting alters tumor cell radiosensitivity. Five human head and neck squamous cell carcinoma (HNSCC) cell lines (SAS, FaDu, HSC4, Cal33, UTSCC5) as well as SAS cells stably transfected with CDK9-EGFP-N1 plasmid or empty vector controls were used. Upon either CDK9 small interfering RNA knockdown or treatment with a pan-CDK inhibitor (ZK304709), colony formation, DNA double strand breaks (DSBs), apoptosis, cell cycling, and expression and phosphorylation of major cell cycle and DNA damage repair proteins were examined. While CDK9 overexpression mediated radioprotection, CDK9 depletion clearly enhanced the radiosensitivity of HNSCC cells without an induction of apoptosis. While the cell cycle and cell cycle proteins were significantly modulated by CDK9 depletion, no further alterations in these parameters were observed after combined CDK9 knockdown with irradiation. ZK304709 showed concentration-dependent cytotoxicity but failed to radiosensitize HNSCC cells. Our findings suggest a potential role of CDK9 in the radiation response of HNSCC cells. Additional studies are warranted to clarify the usefulness to target CDK9 in the clinic.

Radiation and chemotherapy are the main pillars of the current multimodal treatment concept for cancer patients. However, tumor recurrences and resistances still hamper treatment success regardless of advances in radiation beam application, particle radiotherapy, and optimized chemotherapeutics. To specifically intervene at key recurrence- and resistance-promoting molecular processes, the development of potent and specific molecular-targeted agents is demanded for an efficient, safe, and simultaneous integration into current standard of care regimens. Potential targets for such an approach are integrins conferring structural and biochemical communication between cells and their microenvironment. Integrin binding to extracellular matrix activates intracellular signaling for regulating essential cellular functions such as survival, proliferation, differentiation, adhesion, and cell motility. Tumor-associated characteristics such as invasion, metastasis, and radiochemoresistance also highly depend on integrin function. Owing to their dual functionality and their overexpression in the majority of human malignancies, integrins present ideal and accessible targets for cancer therapy. In the following chapter, the current knowledge on aspects of the tumor microenvironment, the molecular regulation of integrin-dependent radiochemoresistance and current approaches to integrin targeting are summarized.

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.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.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.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.

In mammals, the anti-Müllerian hormone (Amh) is responsible for the regression of the Müllerian ducts; therefore, Amh is an important factor of male sex differentiation. The amh gene has been cloned in various vertebrates, as well as in several teleost species. To date, all described species show a sexually dimorphic expression of amh during sex differentiation or at least in differentiated juvenile gonads. We have identified the medaka amh ortholog and examined its expression pattern. Medaka amh shows no sexually dimorphic expression pattern. It is expressed in both developing XY male and XX female gonads. In adult testes, amh is expressed in the Sertoli cells and in adult ovaries in granulosa cells surrounding the oocytes, like in mammals. To better understand the function of amh, we cloned the anti-Müllerian hormone receptor type II (amhrII) ortholog and compared its expression pattern with amh, aromatase (cyp19a1), and scp3. During gonad development, amhrII is coexpressed with medaka amh in somatic cells of the gonads and shows no sexually dimorphic expression. Only the expression level of the Amh type II receptor gene was decreased noticeably in adult female gonads. These results suggest that medaka Amh and AmhrII are involved in gonad formation and maintenance in both sexes.

Glioblastoma multiforme (GBM) is a highly aggressive and extremely lethal cancer and novel molecular therapies are required for optimized multimodal therapy regimes. While focal adhesion kinase (FAK) is regarded as a therapeutic target, its radiosensitizing potential remains to be elucidated in glioblastoma. Thus, FAK was inhibited using the pharmaco logical inhibitor TAE226 and cytotoxicity and radiosensitization of glioblastoma cells were investi- gated in vitro. Monolayer and suspension cell cultures of a panel of glioblastoma cell lines (A172, LN229, U87MG, U138MG, U343MG, DD-HT7607, and DD-T4) were treated with increasing TAE226 concentrations (0-10 µM) alone or in combination with X-rays (0-6 Gy). Subsequently, clono- genic cell survival, expression and the phosphorylation of FAK downstream signaling, apoptosis and autophagy were analyzed. Efficient FAK inhibition by TAE226 mediated significant cytotoxicity and reduced sphere formation in a dose- and time-dependent manner. Two out of seven glio- blastoma cell lines showed radiosensitization. Apoptotic induction by TAE226 was cell line-dependent. The results demonstrated that pharmacological FAK inhibitor TAE226 efficiently reduced clonogenicity and sphere formation in glioblastoma cells without generally modifying their radio- sensitivity. However, future studies are necessary to define the potential of FAK inhibition by TAE226 or other pharmaco- logical inhibitors in combination with radiochemotherapy.

Glioblastoma multiforme (GBM) is the most common brain tumor in adults and characterized by poor clinical outcome due to genetic and epigenetic alterations in resistance-mediating genes and destructive infiltration into the normal brain. Upon therapy, malignant tumors show adaptation to maintain their homeostasis. Two critical determinants of this adaptation process are cell adhesion by beta1 integrins and stress signaling via c-Jun N-terminal kinases (JNK). Here, we evaluated the potential of simultaneous beta1 integrin/JNK targeting to overcome GBM adaptation controlling radiochemoresistance and invasion. Comparative Oncomine data base analysis was performed on the expression of JNK1/2/3 isoforms, beta1 integrin and its ligands in GBM with normal brain. Different human GBM cell populations (patient-derived, stem-like, established) were analyzed for sphere formation, clonogenicity, 3D collagen type-1 invasion, cell cycling, chromatin organization, DNA double strand break (DSB) repair (γH2AX foci assay), broad-spectrum phosphoproteome analysis, FACS analysis and protein expression/phosphorylation upon irradiation (0-6 Gy X-rays) and chemotherapy (Temozolomide) with and without single and simultaneous inhibition of beta1 integrin (AIIB2) and JNK (SP600125, JNKi). The radiochemosensitizing potential of AIIB2/JNKi was also investigated in an orthotopic GBM mouse model using stem-like cells. In contrast to JNK isoforms, beta1 integrin and col1 showed significant overexpression in GBM compared with normal brain. While single inhibition of beta1 integrin and JNK mediated cytotoxicity, only combined targeting resulted in radiochemosensitization. Intriguingly, double AIIB2/JNKi treatment abrogated GBM cell invasion. Importantly, dual beta1 integrin/JNK inhibition elicited a significant reduction in tumor growth and longer survival of mice concomitantly treated with radiotherapy/Temozolomide. Mechanistically, JNK blocking induced beta1 integrin expression for stimulating diverse signaling pathways controlling cell cycling, invasion and radiochemosensitivity. Radiosensitization by AIIB2/JNKi is caused by enhanced ATM phosphorylation and prolonged G2/M cell cycle arrest as well as impaired DNA double strand break repair in the context of elevated levels of euchromatin. In summary, our data reveal that dual beta1 integrin/JNK targeting efficiently impairs adhesion and stress-related adaptation mechanisms involved in radiochemoresistance and invasion. More in-depth evaluation is warranted to clarify the potential of this kind of beta1 integrin/JNK multi-targeting strategy administrated concomitantly to standard radiochemotherapy in patients suffering from GBM. Note: This abstract was not presented at the meeting. Citation Format: Anne Vehlow, Erik Klapproth, Katja Storch, Ellen Dickreuter, Michael Seifert, Antje Dietrich, Rebecca Bütof, Achim Temme, Nils Cordes. Adhesion- and stress-related adaptation mechanisms eliciting glioblastoma radiochemoresistance can be effectively circumvented by beta1 integrin/JNK co-targeting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5838. doi:10.1158/1538-7445.AM2017-5838

Inherent and acquired resistance to targeted therapeutics continues to emerge as a major clinical obstacle. For example, resistance to EGF receptor targeting occurs commonly, more so than was expected, on the basis of preclinical work. Given emerging evidence that cancer cell–substrate interactions are important determinants of therapeutic sensitivity, we examined the impact of cell–fibronectin interactions on the efficacy of the EGF receptor antibody cetuximab, which is used widely for lung cancer treatment. Our results revealed the potential for cell–fibronectin interactions to induce radioresistance of human non–small cell lung cancer cells. Cell adhesion to fibronectin enhanced tumor cell radioresistance and attenuated the cytotoxic and radiosensitizing effects of cetuximab. Both in vitro and in vivo, we found that cetuximab treatment led to a remarkable induction of fibronectin biosynthesis. Mechanistic analyses revealed the induction was mediated by a p38–MAPK–ATF2 signaling pathway and that RNAi-mediated inhibition of fibronectin could elevate the cytotoxic and radiosensitizing potential of cetuximab. Taken together, our findings show how cell adhesion blunts cetuximab, which, by inducing fibronectin, generates a self-attenuating mechanism of drug resistance. Cancer Res; 73(19); 5869–79. ©2013 AACR.

Purpose Cell invasion represents one of the major determinants that treatment has failed for patients suffering from glioblastoma. Contrary findings have been reported for cell migration upon exposure to ionizing radiation. Here, the migration and invasion capability of glioblastoma cells on and in collagen type I were evaluated upon irradiation with X-rays or carbon ions. Methods and Materials Migration on and invasion in collagen type I were evaluated in four established human glioblastoma cell lines exposed to either X-rays or carbon ions. Furthermore, clonogenic radiation survival, proliferation (5-bromo-2-deoxyuridine positivity), DNA double-strand breaks (γH2AX/53BP1-positive foci), and expression of invasion-relevant proteins (eg, β1 integrin, FAK, MMP2, and MMP9) were explored. Migration and invasion assays for primary glioblastoma cells also were carried out with X-ray irradiation. Results Neither X-ray nor carbon ion irradiation affected glioblastoma cell migration and invasion, a finding similarly observed in primary glioblastoma cells. Intriguingly, irradiated cells migrated unhampered, despite DNA double-strand breaks and reduced proliferation. Clonogenic radiation survival was increased when cells had contact with extracellular matrix. Specific inhibition of the β1 integrin or proliferation-associated signaling molecules revealed a critical function of JNK, PI3K, and p38 MAPK in glioblastoma cell invasion. Conclusions These findings indicate that X-rays and carbon ion irradiation effectively reduce proliferation and clonogenic survival without modifying the migration and invasion ability of glioblastoma cells in a collagen type I environment. Addition of targeted agents against members of the MAPK and PI3K signaling axis to conventional chemoradiation therapy seems potentially useful to optimize glioblastoma therapy.

Assessment of phosphorylated histone H2AX (γH2AX) foci as a measure for double-strand breaks (DSB) is a common technique. Since visual interpretation is time-consuming and influenced by subjective factors, we adapted the pattern recognition algorithms of autoantibodies to automated reading of γH2AX foci.DSB formation was assessed by detection of γH2AX foci after exposition of thyreocyte rat cell line to (188)Re. We used pattern recognition algorithms of the automated fluorescence interpretation system AKLIDES(®) for evaluation of γH2AX foci. Manual investigation was performed by three laboratories involving five observers. The results were compared by determining correlation and inter-laboratory variability.The study confirmed the adaptation of automated interpretation system AKLIDES® to automated assessment of γH2AX foci in irradiated cells. Both manual and automated quantification resulted in increasing focus numbers depending on dose. Comparison of automated reading with visual assessment for five manual observers resulted in a determination coefficient of R(2) = 0.889. The inter-laboratory variability for five manual investigators of three laboratories was 38.4 %.The interpretation system AKLIDES(®) demonstrated a high correlation with visually observed results. High inter-laboratory variability found for manual investigations revealed the usefulness for a standardized technique for evaluation of γH2AX foci.

Cell shape and architecture are determined by cell-extracellular matrix interactions and have profound effects on cellular behavior, chromatin condensation, and tumor cell resistance to radiotherapy and chemotherapy. To evaluate the role of chromatin condensation for radiation cell survival, tumor cells grown in three-dimensional (3D) cell cultures as xenografts and monolayer cell cultures were compared. Here, we show that increased levels of heterochromatin in 3D cell cultures characterized by histone H3 deacetylation and induced heterochromatin protein 1α expression result in increased radiation survival and reduced numbers of DNA double strand breaks (DSB) and lethal chromosome aberrations. Intriguingly, euchromatin to heterochromatin–associated DSBs were equally distributed in irradiated 3D cell cultures and xenograft tumors, whereas irradiated monolayer cultures showed a 2:1 euchromatin to heterochromatin DSB distribution. Depletion of histone deacetylase (HDAC) 1/2/4 or application of the class I/II pharmacologic HDAC inhibitor LBH589 induced moderate or strong chromatin decondensation, respectively, which was translated into cell line–dependent radiosensitization and, in case of LBH589, into an increased number of DSBs. Neither growth conditions nor HDAC modifications significantly affected the radiation-induced phosphorylation of the important DNA repair protein ataxia telangiectasia mutated. Our data show an interrelation between cell morphology and cellular radiosensitivity essentially based on chromatin organization. Understanding the molecular mechanisms by which chromatin structure influences the processing of radiation-induced DNA lesions is of high relevance for normal tissue protection and optimization of cancer therapy. Cancer Res; 70(10); 3925–34. ©2010 AACR.

Background and purpose: Resistance of pancreatic ductal adenocarcinoma (PDAC) to chemo- and radiotherapy is a major obstacle. The integral membrane protein Caveolin-1 (Cav-1) has been suggested as a potent target in human pancreatic carcinoma cells. Materials and methods: Human pancreatic tumor cells were examined in a three-dimensional (3D) cell culture model with regard to clonogenic survival, apoptosis, radiogenic DNA-double strand breaks and protein expression and phosphorylation under siRNA-mediated knockdown of Cav-1 without and in combination with irradiation (X-rays, 0–6 Gy). Immunohistochemistry was used to assess Cav-1 expression in biopsies from patients with PDAC. Results: Tumor cells in PDAC showed significantly higher Cav-1 expression relative to tumor stroma. Cav-1 knockdown significantly reduced b1 integrin expression and Akt phosphorylation, induced Caspase 3- and Caspase 8-dependent apoptosis and enhanced the radiosensitivity of 3D cell cultures. While cell cycling and Cav-1 promoter activity remained stable, Cav-1 knockdown-induced radiosensitization correlated with elevated numbers of residual DNA-double strand breaks. Conclusions: Our data strongly support the concept of Cav-1 as a potent target in pancreatic carcinoma cells due to radiosensitization and Cav-1 overexpression in tumor cells of PDAC. 3D cell cultures are powerful and useful tools for the testing of novel targeting strategies to optimize conventional radio- and chemotherapy regimes for PDAC.

Viele Organisationen setzen Communication Center ein, um eine effiziente und effektive Interaktion mit ihren Kunden zu erreichen. 1999 gab es in Europa bereits 12.750 Communication Center. Es wird erwartet, das sich diese Zahl bis 2006 auf 28.000 erhoht (Frost und Sullivan 2000).

Integrin-mediated cell-extracellular matrix (ECM) interactions confer cancer cell resistance to therapy. Our own data and data of others generated in three-dimensional (3D) ECM-based cell cultures and in vivo provided evidence that particularly beta1 integrin targeting potently reduces this resistance involving downstream integrin signaling mediators like focal adhesion kinase, cortactin and JNK1. However, it remains unknown whether beta1 integrin inhibition affects the repair of radiation-induced DNA double strand breaks (DSB) and their distribution in eu- and heterochromatic DNA regions. Here, we show that 3D growth (cell culture, xenograft models) increased the amount of heterochromatin in human head and neck squamous cell (HNSCC) and lung carcinoma cell lines relative to 2D, induced higher radioresistance, reduced the number of chromosomal aberrations and gammaH2AX/53BP1-positive foci, which was accompanied by a shift of the euchromatin-to-heterochromatin DSB distribution from a 2:1 (2D) to a 1:1 (3D). Upon beta1 integrin inhibition using the inhibitory monoclonal antibody AIIB2 or siRNA, cells grown in 3D or as xenografts in nude mice were radiosensitized or showed a significant growth delay, respectively. The disruption of beta1 integrin-mediated cell-ECM interactions induced an increase in heterochromatin levels indicated by HP1alpha and H3K9me3 elevation. In line with these findings was a strong impairment of both ATM and DNA-PK and their associated downstream signaling pathways (e.g. Chk2, Mre11, Nbs1, Rad50) in beta1 integrin inhibited, irradiated cells relative to IgG isotype controls. In contrast to unchanged number of heterochromatic foci identified in stably transfected HP1alpha cells, kinetic DSB measurements revealed an increased number of euchromatic foci upon beta1 integrin blocking, which evidently showed strongly perturbed DSB repair. In conclusion, our data generated in 3D cell culture and tumor xenograft models suggest a regulatory function of beta1 integrin signaling in the repair of radiogenic DSBs and the organization of chromatin. In addition to our understanding of the initial steps deactivated upon beta1 integrin blocking, these findings bridge membrane bound integrin function to nuclear DNA repair processes, thus providing further insights into how integrins confer cancer cell radioresistance and why integrin targeting is potentially useful as adjuvant to conventional radio- and radiochemotherapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-211. doi:1538-7445.AM2012-LB-211

monitoring of tumor hypoxia and demonstrated a transient increase in tumor hypoxia in response to treatment with patupilone alone. To investigate whether the supra-additive tumor growth delay effect of the combined treatment modality (patupilone/IR) is influenced by the level of patupilone-increased tumor hypoxia, tumors were irradiated at the time point of the lowest and the highest level of patupilone-increased tumor hypoxia. Interestingly the hypoxia-inducing effect of patupilone dominated over the effect of the combined treatment modality on the level of tumor hypoxia, but had no effect on efficacy-related endpoints. In parallel the metabolic status of A549 tumors was determined ex vivo by the immersion of dried/heat-inactivated tumor sections in an ATP, lactate or glucose-depending luciferase-containing buffer system. Integrated light output was detected in a highly sensitive bioluminescent detection system (IVIS). Treatment of A549 wild type tumors with patupilone, IR and in combination significantly reduced lactate levels and drastically increased glucose levels in comparison to untreated tumors. Interestingly, these changes were only minimal in tumors derived from patupilone-resistant cells (A549EpoB40). ATP levels of all tumors tested did not change under any treatment. When compared with other histological endpoints, basal and treatment-dependent changes of lactate levels in the different tumors did not correlate with basal and treatment-induced changes of tumor hypoxia or microvessel density, but mainly correlated with the proliferative activity and the tumor growth response to treatment. This study shows that the tumor milieu is responsive to different treatment-modalities and that detailed insights into the dynamics of hypoxia and metabolism will contribute to the improvement and adaptation of existing radiochemotherapies.