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  • 1
    Keywords: RECEPTOR ; ANGIOGENESIS ; APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; ENDOTHELIAL-CELLS ; EXPRESSION ; FLK-1/KDR ; GROWTH ; GROWTH-FACTOR ; IN-VITRO ; INHIBITOR ; INVASION ; IONIZING-RADIATION ; IRRADIATION ; proliferation ; PROTECTION ; radiotherapy ; SURVIVAL ; tumor ; TUMOR-CELLS
    Abstract: In recent decades, radiation research has concentrated primarily on the cancer cell compartment. Much less is known about the effect of ionizing radiation on the endothelial cell compartment and the complex interaction between tumor cells and their microenvironment. Here we report that ionizing radiation is a potent antiangiogenic agent that inhibits endothelial cell survival, proliferation, tube formation and invasion. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were able to reduce the radiosensitivity of endothelial cells. Yet, it is also found that radiation induces angiogenic factor production by tumor cells that can be abrogated by the addition of antiangiogenic agents. Receptor tyrosine kinase inhibitors of Flk-1/KDR/VEGFR2, FGFR1 and PDGFRbeta, SU5416, and SU6668 enhanced the antiangiogenic effects of direct radiation of the endothelial cells. In a coculture system of PC3 prostate cancer cells and endothelial cells, isolated irradiation of the PC3 cells enhanced endothelial cell invasiveness through a Matrigel matrix, which was inhibited by SU5416 and SU6668. Furthermore, ionizing radiation up-regulated VEGF and basic fibroblast growth factor in PC3 cells and VEGFR2 in endothelial cells. Together these findings suggest a radiation-inducible protective role for tumor cells in the support of their associated vasculature that may be down- regulated by coadministration of angiogenesis inhibitors., These results rationalize concurrent administration of angiogenesis inhibitors and radiotherapy in cancer treatment
    Type of Publication: Journal article published
    PubMed ID: 12839971
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  • 2
    Keywords: RECEPTOR ; ANGIOGENESIS ; APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; ENDOTHELIAL-CELLS ; GROWTH ; IN-VITRO ; INHIBITOR ; IONIZING-RADIATION ; IRRADIATION ; proliferation ; radiotherapy ; SURVIVAL ; tumor ; TUMOR-CELLS ; AGENTS ; CELL ; COMBINATION ; Germany ; human ; INHIBITION ; KINASE ; MODEL ; MODELS ; PROSTATE ; THERAPY ; TYROSINE KINASE ; VITRO ; EXPOSURE ; NEW-YORK ; DRUG ; cell line ; LINES ; radiation ; ACTIVATION ; DNA ; primary ; FLOW ; CELL-LINES ; PHOSPHORYLATION ; treatment ; ASSAY ; EFFICACY ; prostate cancer ; PROSTATE-CANCER ; CELL-LINE ; chemotherapy ; LINE ; CANCER-CELLS ; INVOLVEMENT ; STRATEGIES ; FLOW-CYTOMETRY ; TUMOR CELLS ; TUMOR-CELL-LINES ; NECK-CANCER ; alimta ; ANGIOGENESIS INHIBITION ; antiangiogenesis ; CONCURRENT ; MEDICAL PROGRESS ; MULTITARGETED ANTIFOLATE ; pemetrexed ; SU5416 ; triple combination ; XENOGRAFTS
    Abstract: Purpose: This is the first preclinical report evaluating a trimodal therapy consisting of irradiation, chemotherapy, antiangiogenesis in the context of a multimodal anticancer strategy. The combination of the folate antimetabolite pemetrexed, SU5416, a receptor tyrosine kinase inhibitor of VEGFR2, and irradiation was investigated in human endothelial cells and tumor cell lines. Methods and Materials: Primary isolated human umbilical vein endothelial cells (HUVEC), human dermal microvascular endothelial cells (HDMEC), and human glioblastoma (U87) and prostate cancer cells (PC3) were exposed to pemetrexed (2 h) alone and in combination with SU5416 (2 h). When combined with irradiation up to 8 Gy, fixed concentrations of pemetrexed (1.06 muM) and SU5416 (1.0 muM) were used. Proliferation and clonogenic assays were conducted with endothelial and tumor cells. The migration/invasion ability of endothelial cells and the ability to produce tubular structures were tested in Matrigel and tube formation assays. Apoptosis was measured by sub-G1 DNA and caspase-3 flow cytometry. To investigate underlying cell signaling, immunocytochemistry was used to detect Akt survival signaling involvement. Results: Triple combination using only a low-toxicity drug exposure of pemetrexed and SU5416 results in greater response than each treatment alone or than each combination of two modalities in all tested endothelial and tumor cell models. Triple combination substantially inhibits proliferation, migration/invasion, tube formation, and clonogenic survival. Triple combination also induced the highest rate of apoptosis in HDMEC and HUVEC as indicated by sub-1 G1 and caspase-3 assessment. Interestingly, triple combination therapy also reduces proliferation and clonogenic survival significantly in U87 and PC3 tumor cell lines. SU5416 potently inhibited Akt phosphorylation which could be induced by radiation and radiochemotherapy in human endothelial cells. Conclusions: Our findings demonstrate the high antiendothelial/antitumoral efficacy of the concurrent administration of irradiation, chemotherapy, and angiogenesis inhibition in vitro. A potential explanation for the favorable combination would be that VEGF signaling inhibition downregulates Akt survival signaling upon activation by radiation and/or chemotherapy. The data also suggest that endothelial cell apoptosis may have an important role in the benefits of the presented therapy. (C) 2004 Elsevier Inc
    Type of Publication: Journal article published
    PubMed ID: 15519795
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  • 3
    Keywords: CELLS ; GROWTH ; IRRADIATION ; carcinoma ; Germany ; MODEL ; SYSTEM ; EXPOSURE ; radiation ; TIME ; DNA ; INDUCTION ; RAT ; RATS ; FLOW ; cell cycle ; CYCLE ; treatment ; BREAST-CANCER ; PROGRESSION ; CARCINOMAS ; DOSE-RATE BRACHYTHERAPY ; INITIATION ; CYCLE ARREST ; cell cycle progression ; animal model ; DOSE-RATE ; low dose rate brachytherapy ; prostate Dunning tumour ; pulsed dose rate brachytherapy ; RATE INTERSTITIAL BRACHYTHERAPY
    Abstract: Purpose: The study consisted of two treatment arms comparing the effects of CLDR (continuous low dose rate) and PDR ( pulsed dose rate) brachytherapy on cell cycle progression in a radioresistant rat prostate tumour model. Materials and methods: Interstitial PDR and CLDR brachytherapy ( both 192-Ir, 0.75 Gy/h) were administered to Dunning prostate R3327-AT1 carcinomas transplanted subcutaneously into the thigh of Copenhagen rats. Increasing doses of up to 20 as well as up to 40 Gy were applied. Cell cycle distributions of the aneuploid tumour cell subpopulations were determined at 4 h ( 3 Gy), 24 h ( 18 Gy), 48 h ( 20 and 36 Gy), as well as during the subsequent redistribution period ( 20 and 40 Gy) at 72, 96, and 120 h. Tumours either implemented with an empty tubing system (n = 5) or under undisturbed growth (n = 5) served as controls. Three animals were irradiated per time point and exposure condition. At least two flow cytometrical analyses were carried out per animal. Results: The aneuploid cells possessed a constant DNA-Index of 1.9 +/- 0.06. In contrast to sham-treated controls, the aneuploid cell fraction with G2/M DNA content was significantly increased (p 〈 0.05) after initiation of both, CLDR and PDR brachytherapy. However, CLDR resulted in an earlier accumulation of tumour cells in G2/M (24 h: 28% CLDR vs. 19% PDR, p 〈 0.05) with a concomitant reduction of cells in G1, whereas PDR yielded delayed, but then more pronounced cell cycle changes, particularly expressed during the redistribution period after both 20 and 40 Gy. Conclusion: CLDR and PDR brachytherapy showed differential effects on cell cycle progression. The induction of a significantly earlier but also less persistent G2/M cell cycle arrest after CLDR compared to PDR brachytherapy implies that a substantially higher fraction of tumour cells are irradiated in G2/M after CLDR
    Type of Publication: Journal article published
    PubMed ID: 16638716
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  • 4
    Keywords: RECEPTOR ; ANGIOGENESIS ; APOPTOSIS ; CANCER ; CELLS ; ENDOTHELIAL-CELLS ; GROWTH ; GROWTH-FACTOR ; IN-VITRO ; IONIZING-RADIATION ; IRRADIATION ; proliferation ; radiotherapy ; SURVIVAL ; tumor ; AGENTS ; CELL ; CELL-PROLIFERATION ; COMBINATION ; FACTOR RECEPTOR ; Germany ; human ; IN-VIVO ; INHIBITION ; KINASE ; PATHWAY ; PROSTATE ; THERAPY ; tumor growth ; VITRO ; DENSITY ; DRUG ; TUMORS ; MICE ; radiation ; PATIENT ; MECHANISM ; INDEX ; TYROSINE KINASE INHIBITOR ; DESIGN ; UP-REGULATION ; prostate cancer ; PROSTATE-CANCER ; DAMAGE ; MUSCLE ; MIGRATION ; experimental design ; CELL-MIGRATION ; TUMOR ANGIOGENESIS ; VEGF ; signaling ; AGENT ; ONCOLOGY ; RE ; antiangiogenesis ; SU5416 ; TUMOR-GROWTH ; THERAPIES ; INCREASE ; cell proliferation ; cell migration ; USA ; vascular endothelial growth factor ; cancer research ; GLIOBLASTOMA ; GROWTH-FACTOR-RECEPTOR ; SMOOTH-MUSCLE-CELLS ; ENDOTHELIAL GROWTH ; MUSCLE-CELLS ; tumor therapy ; radiation dose ; FRACTIONATED-IRRADIATION ; SU6668
    Abstract: Purpose: Investigations on the combination of radiotherapy with vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) antiangiogenic agents, which has the potential to improve the clinical outcome in cancer patients. Experimental Design: Here, we analyze the combined VEGF (SU5416) and PDGF (SU6668) receptor tyrosine kinase inhibition with irradiation in human endothelium (HUVEC), prostate cancer (PC3), and glioblastoma (U87) in vitro and in vivo. Results: Combined inhibition of VEGF and PDGF signaling resulted in enhanced apoptosis, reduced cell proliferation, and clonogenic survival as well as reduced endothelial cell migration and tube formation compared with single pathway inhibition. These effects were further enhanced by additional irradiation. Likewise, in PC3 and U87 tumors growing s.c. on BALB/c nu/nu mice, dual inhibition of VEGF and PDGF signaling significantly increased tumor growth delay versus each monotherapy. Interestingly, radiation at similar to 20% of the dose necessary to induce local tumor control exerts similar tumor growth-inhibitory effects as the antiangiogenic drugs given at their maximum effective dose. Addition of radiotherapy to both mono- as well as dual-antiangiogenic treatment markedly increased tumor growth delay. With respect to tumor angiogenesis, radiation further decreased microvessel density (CD31 count) and tumor cell proliferation (Ki-67 index) in all drug-treated groups. Of note, the slowly growing PC3 tumor responded better to the antiangiogenic drug treatments than the faster-growing U87 tumor. In addition to the beneficial effect of abrogating VEGF survival signaling when combined with radiation, we identified here a novel mechanism for the tumor escape from radiation damage. We found that radiation induced up-regulation of all four isoforms of PDGF (A-D) in endothelial cells supporting adjacent smooth muscle cells resulting in a prosurvival effect of radiation. The addition of SU6668 attenuated this undesirable paracrine radiation effect, which may rationalize the combined application of radiation with PDGF signaling inhibition to increase antitumor effects. Conclusion: A relative low radiation dose markedly enhances local antitumor effects of combined VEGF and PDGF signaling inhibition, suggesting a promising combination regimen for local tumor treatment with radiotherapy remaining an essential element
    Type of Publication: Journal article published
    PubMed ID: 18381963
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  • 5
    Abstract: Purpose: Histone deacetylase inhibitors (HDACIs) can enhance the sensitivity of cells to photon radiation treatment (XRT) by altering numerous molecular pathways. We investigated the effect of pan-HDACIs such as suberoylanilide hydroxamic acid (SAHA) on radiation response in two osteosarcoma (OS) and two rhabdomyosarcoma (RMS) cell lines. Methods and Materials: Clonogenic survival, cell cycle analysis, and apoptosis were examined in OS (KHOS-24OS, SAOS2) and RIM (A-204, RD) cell lines treated with HDACI and HDACI plus XRT, respectively. Protein expression was investigated via immunoblot analysis, and cell cycle analysis and measurement of apoptosis were performed using flow cytometry. Results: SAHA induced an inhibition of cell proliferation and clonogenic survival in OS and RMS cell lines and led to a significant radiosensitization of all tumor cell lines. Other HDACI such as M344 and valproate showed similar effects as investigated in one OS cell line. Furthermore, SAHA significantly increased radiation-induced apoptosis in the OS cell lines, whereas in the RMS cell lines radiation-induced apoptosis was insignificant with and without SAHA. In all investigated sarcoma cell lines, SAHA attenuated radiation-induced DNA repair protein expression (Rad51, Ku80). Conclusion: Our results show that HDACIs enhance radiation action in OS and RMS cell lines. Inhibition of DNA repair, as well as increased apoptosis induction after exposure to HDACIs, can be mechanisms of radiosensitization by HDACIs. (C) 2010 Elsevier Inc
    Type of Publication: Journal article published
    PubMed ID: 20646843
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  • 6
    Keywords: APOPTOSIS ; EXPRESSION ; IN-VITRO ; IRRADIATION ; radiotherapy ; THERAPY ; TISSUE ; p53 ; sensitivity ; CANCER-THERAPY ; HISTONE DEACETYLASE INHIBITORS ; STRAND BREAKS ; HISTONE DEACETYLASE INHIBITION ; SUBEROYLANILIDE HYDROXAMIC ACID ; H2AX PHOSPHORYLATION ; heavy ion radiotherapy ; GAMMA-H2AX FOCI ; Infantile sarcoma ; RADIATION RESPONSE ; SAHA
    Abstract: Introduction: The pan-HDAC inhibitor (HDACI) suberoylanilide hydroxamic acid (SAHA) has previously shown to be a radio-sensitizer to conventional photon radiotherapy (XRT) in pediatric sarcoma cell lines. Here, we investigate its effect on the response of two sarcoma cell lines and a normal tissue cell line to heavy ion irradiation (HIT). Materials and methods: Clonogenic assays after different doses of heavy ions were performed. DNA damage and repair were evaluated by measuring gamma H2AX via flow-cytometry. Apoptosis and cell cycle analysis were also measured via flow cytometry. Protein expression of repair proteins, p53 and p21 were measured using immunoblot analysis. Changes of nuclear architecture after treatment with SAHA and HIT were observed in one of the sarcoma cell lines via light microscopy after staining towards chromatin and gamma H2AX. Results: Corresponding with previously reported photon data, SAHA lead to an increase of sensitivity to heavy ions along with an increase of DSB and apoptosis in the two sarcoma cell lines. In contrast, in the osteoblast cell line (hFOB 1.19), the combination of SAHA and HIT showed a significant radio-protective effect. Laser scanning microscopy revealed no significant morphologic changes after HIT compared to the combined treatment with SAHA. Immunoblot analysis revealed no significant up or down regulation of p53. However, p21 was significantly increased by SAHA and combination treatment as compared to HIT only in the two sarcoma cell lines - again in contrast to the osteoblast cell line. Changes in the repair kinetics of DSB p53-independent apoptosis with p21 involvement may be part of the underlying mechanisms for radio-sensitization by SAHA. Conclusion: Our in vitro data suggest an increase of the therapeutic ratio by the combination of SAHA with HIT in infantile sarcoma cell lines
    Type of Publication: Journal article published
    PubMed ID: 21933400
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  • 7
  • 8
    Keywords: CANCER ; CELLS ; EXPRESSION ; GROWTH ; INVASION ; SURVIVAL ; VITRO ; DENSITY ; MICE ; radiation ; MIGRATION ; GROWTH-FACTOR-BETA ; CELL-MIGRATION ; human glioma ; antiangiogenic therapy ; GLIOBLASTOMA ; VESSEL NORMALIZATION
    Abstract: Here we investigate the effects of the novel transforming growth factor-beta receptor I (TGF-beta RI) serine/threonine kinase inhibitor LY2109761 on glioblastoma when combined with the present clinical standard combination regimen radiotherapy and temozolomide (TMZ). Human GBM U87 (methylated MGMT promoter), T98 (unmethylated MGMT promoter), and endothelial cells (HUVECs) were treated with combinations of LY2109761, TMZ, and radiation. We found that LY2109761 reduced clonogenic survival of U87 and T98 cells and further enhanced the radiation-induced anticlonogenicity. In addition, LY2109761 had antimigratory and antiangiogenic effects in Matrigel migration and tube formation assays. In vivo, in human xenograft tumors growing subcutaneously on BALB/c nu/nu mice, LY2109761 delayed tumor growth alone and in combination with fractionated radiation and TMZ. Interestingly, as expected, the methylated U87 model was more sensitive to TMZ than the unmethylated T98 model in all experiments, whereas the opposite was found for LY2109761. Moreover, with respect to tumor angiogenesis, while LY2109761 decreased the glioblastoma proliferation index (Ki-67) and the microvessel density (CD31 count), the relative pericyte coverage (alpha-SMA/CD31 ratio) increased in particular after triple therapy, suggesting a vascular normalization effect induced by LY2109761. This normalization could be attributed in part to a decrease in the Ang-2/Ang-1 messenger RNA ratio. LY2109761 also reduced tumor blood perfusion as quantified by noninvasive dynamic contrast-enhanced magnetic resonance imaging. Together, the data indicate that the addition of a TGF-beta RI kinase inhibitor to the present clinical standard (radiation plus TMZ) has the potential to improve clinical outcome in human glioblastoma, especially in patients with unmethylated MGMT promoter status
    Type of Publication: Journal article published
    PubMed ID: 21677877
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  • 9
    Keywords: APOPTOSIS ; CANCER ; CELLS ; EXPRESSION ; GROWTH ; proliferation ; radiotherapy ; IN-VIVO ; THERAPY ; TUMORS ; MOUSE ; FOCI ; PET ; KINETICS ; radiosensitivity ; XENOGRAFTS ; SOLID TUMORS ; osteosarcoma ; in vivo ; HISTONE DEACETYLASE INHIBITION ; SUBEROYLANILIDE HYDROXAMIC ACID ; RADIATION RESPONSE ; H2AX ; Malignant rhabdoid tumor ; VORINOSTAT
    Abstract: Purpose Histone deacetylase inhibitors are promising new substances in cancer therapy and have also been shown to sensitize different tumor cells to irradiation (XRT). We explored the effect as well as the radiosensitizing properties of suberoylanilide hydroxamic acid (SAHA) in vivo in a malignant rhabdoid tumor (MRT) mouse model. Methods and material Potential radiosensitization by SAHA was assessed in MRT xenografts by analysis of tumor growth delay, necrosis (HE), apoptosis (TUNEL), proliferation (ki-67) and gammaH2AX expression as well as dynamic 18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG -PET) after treatment with either SAHA alone, single-dose (10 Gy) or fractionated XRT (3 x 3Gy) solely as well as in combination with SAHA compared to controls. RESULTS: SAHA only had no significant effect on tumor growth. Combination of SAHA for 8 days with single-dose XRT resulted in a higher number of complete remissions, but failed to prove a significant growth delay compared to XRT only. In contrast fractionated XRT plus SAHA for 3 weeks did induce significant tumor growth delay in MRT-xenografts. The histological examination showed a significant effect of XRT in tumor necrosis, expression of Ki-67, gammaH2AX and apoptosis. SAHA only had no significant effect in the histological examination. Comparison of xenografts treated with XRT and XRT plus SAHA revealed a significantly increased gammaH2AX expression and apoptosis induction in the mice tumors after combination treatment with single-dose as well as fractionated XRT. The combination of SAHA with XRT showed a tendency to increased necrosis and decrease of proliferation compared to XRT only, which, however, was not significant. The 18F-FDG-PET results showed no significant differences in the standard uptake value or glucose transport kinetics after either treatment. CONCLUSION: SAHA did not have a significant effect alone, but proved to enhance the effect of XRT in our MRT in vivo model.
    Type of Publication: Journal article published
    PubMed ID: 22458853
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  • 10
    Keywords: IONIZING-RADIATION ; IRRADIATION ; SURVIVAL ; DIFFERENTIATION ; TISSUE ; fibroblasts ; LINE ; sensitivity ; STROMAL CELLS ; HUMAN BONE-MARROW
    Abstract: Mesenchymal stem cells (MSCs) participate in regeneration of tissues damaged by ionizing radiation. However, radiation can damage MSCs themselves. Here we show that cellular morphology, adhesion and migration abilities were not measurably altered by photon or carbon ion irradiation. The potential for differentiation was unaffected by either form of radiation, and established MSC surface markers were found to be stably expressed irrespective of radiation treatment. MSCs were able to efficiently repair DNA double strand breaks induced by both high-dose photon and carbon ion radiation. We have shown for the first time that MSCs are relatively resistant to therapeutic carbon ion radiotherapy. Additionally, this form of radiation did not markedly alter the defining stem cell properties or the expression of established surface markers in MSCs.
    Type of Publication: Journal article published
    PubMed ID: 25504442
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