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Prognostic role of Ebstein Barr virus latent membrane Protein-1 and Interleukin-10 expression in patients with nasopharyngeal carcinoma
234
I. J. Radiation Oncology
2018
● Biology ● Physics
Volume 51, Number 3, Supplement 1, 2001
Iododeoxyuridine (IdUrd)-Induced Cytotoxicity and Radiosensitivity Involves the Base Excision Repair (BER) Protein XRCC1
T.J. Kinsella, P. Taverna, H.S. Hwang, D. Zarling Radiation Oncology, University Hospitals of Cleveland, Cleveland, OH IdUrd is a halogenated thymidine analogue recognized as an effect IdUrd is a halogenated thymidine analogue recognized as an effect in vitro and in vivo radiosensitizer in human cancers. IdUrd-related cytotoxicity and/or radiosensitization were correlated with the extent of IdUrd-DNA incorporation replacing thymidine. The repair of intermediates including DNA Single Strand Breaks (SSB) and Double Strand Breaks (DSB) appears related to its cytotoxicity. Recently, we reported that DNA Mismatch Repair (MMR) deficient human tumor and murine cells show increased IdUrd-DNA incorporation and enhanced radiosensitization compared to geneticallymatched, MMR-proficient cells (Cancer Res. 59:1840-1845, 1999; Cancer Res. 60:5773-5780, 2000). As the thymidine analogue would not be expected to form DNA mismatches, we questioned whether Base Excision Repair (BER) might be responsible, in part, for our observations. To directly assess the role of BER in IdUrd cytotoxicity and radiosensitization, we used genetically-matched CHO cells, with (AA8 cells) and without (EM9 cells) XRCC1 expression. XRCC1 plays a central role in processing and repairing SSB and DSB. We found that EM9 cells were significantly more sensitive than parental AA8 cells to IdUrd alone (10-fold as IC50) and to IdUrd ⫹ Ionizing Radiation (⬎ 1 log at 1 M IdUrd and ⬎ 2 log at 3 M IdUrd). EM9 cells transfected with a cosmid vector carrying the human XRCC1 gene, showed responses to IdUrd similar to AA8 cells. Levels of IdUrd-DNA incorporation in EM9, AA8 and the transfected EM9 cells were identical following drug treatment. However, enhanced DNA damage was only found in EM9 cells as measured by pulse field gel electrophoresis. These data suggest that XRCC1-mediated BER participates in the “repair” of IdUrd-modified DNA and the inhibition of BER potentiates IdUrd-mediated radiosensitization.
2019
2-Deoxy-d-Glucose is a Cytotoxic and Radiosensitizing Agent in Tumor Cells
1
X. Lin , R. Aft2, D.R. Spitz3, D. Gius1 1 Section of Cancer Biology, Radiation Oncology Center, Washington University, St. Louis, MO, 2Department of Surgery, Washington University, St. Louis, MO, 3Free Radical and Radiation Biology Program, University of Iowa, Iowa City, IA Purpose: It is a well-established observation that tumor cells demonstrate altered metabolism when compared to normal, non-transformed cells. The most common alteration involves intracellular glucose utilization and the loss of regulation of glycolytic metabolism and respiration. This unique property of cancer cells has been utilized in cancer imaging and in researches of cancer treatment. Glucose deprivation was recently shown to selectively induce cell death via oxidative stress, and transformed cells responds to glucose deprivation differently than normal cells (J. Biol. Chem. 273:5294-5299; Ann. NY Acad. Sci. 899:349-362). 2-Deoxy-d-glucose (2-DG), a competitive glucose analog, is a potent inhibitor of glycolytic metabolism. 2-DG has been shown to inhibit growth of experimental mouse and rat tumors. Based on these observations, we hypothesized that 2-DG may also be cytotoxic via a mechanism involving oxidative stress; furthermore 2-DG may be a potential radiosensitizer since oxidative stress is one possible mechanism for ionizing radiation induced cell death. Materials and Methods: All cells were maintained in standard growth environment. A normal rat fibroblast cell line (208F) and its v-fos gene transformed counterpart (FBJ/R) are gifts from Dr. T. Curran at St. Jude Children’s Research Hospital, Memphis, TN. Twenty-four hours prior to drug treatment, cells were seeded at appropriate density in T-25 flasks. At the beginning of drug treatment, 2DG (final concentration of 4-10 mM) or N-acetylcysteine (NAC, final concentration 30 mM) was added to each flask containing 5 ml of fresh warmed medium and 1.5-2 x 106 cells. The total length of drug treatment varied from 0–72 hours. Cells were irradiated at the end of drug treatment. Fractional cell survival was evaluated by the standard colony forming assay. Results: When HeLa cells were treated with 2-DG, cell survival decreased to various degrees (0.9 to 0.1) depending on the drug concentration (4-10 mM) and length of treatment (4-72 h). When HeLa cells were treated with 2-DG (6 mM, 16 h) before exposure to ionizing radiation, their radiosensitivity were increased by a factor of 1.4 at the 50% isosurvival level, or 1.3 at the 10% isosurvival level. Treatment with a thiol antioxidant, NAC, protected HeLa cells against the cytotoxic effects of 6 mM 2-DG for up to 16 hours. In addition, treatment with NAC diminished the radiosensitization from 2-DG. The above results suggested a use for 2-DG. However, if 2-DG is to be of clinical significance, there has to be a greater cytotoxic effect on tumor versus normal cells. Thus we tested 2-DG on normal (208F) and matched transformed (FBJ/R) rat fibroblasts. At 6 mM of 2-DG, survival for the transformed FBJ/R cells was 0.85, 0.53, 0.21, after 4, 8, 24h of drug treatment, compared with 0.95, 0.75, 0.41 for the 208F cells. Additionally, the radiosensitizing effect of 2-DG was more pronounced in FBJ/R cells. At 2 Gy, 2-DG treatment (6 mM, 4 h) increased the radiosensitivity by a factor of 1.31 for FBJ/R cells, and only 1.08 for 208F cells. Conclusion: The results of these experiments demonstrate that 2-DG is a cytotoxic, as well as a radiosensitizating agent via a mechanism involving changes in intracellular oxidation/reduction status. Since tumor cells have altered glucose metabolism, it seems logical that tumor cells would be more sensitive to 2-DG. The above results with normal and matched transformed rat fibroblasts appear to validate a differential cytotoxic and radiosensitizing effects of 2-DG between normal and transformed cells, and suggest a possible clinical usefulness for 2-DG. This work is currently being pursued in mice xenograph experiments. (Supported by CA72602, ACS-IRG-58-010-43, and HL51469).
2020
Prognostic Role of Ebstein Barr Virus Latent Membrane Protein-1 and Interleukin-10 Expression in Patients with Nasopharyngeal Carcinoma
A.F. Korcum, E. Ozyar, A. Ayhan, I.L. Atahan Radiation Oncology, Hacettepe University, Ankara, Turkey Purpose: We aimed to investigate Ebtein Barr Virus (EBV) Latent Membran Protein-1 (LMP-1) and Interleukin-10 (IL-10) expression in 74 nasopharyngeal carcinoma (NPC) patients and to evaluate their prognostic significance. Material and Methods: Between 1993 and 1999, 144 patients were treated with the diagnosis of non-metastatic NPC at our
Proceedings of the 43rd Annual ASTRO Meeting
department. The expression of LMP-1 and IL-10 was investigated by using immunohistochemical approach in 74 (53 male, 21 female) patients whose paraffin embedded tissue samples were obtained. A detailed histopathological analysis including degree of apoptosis and lymphocyte infiltration was made and all patients were reclassified according to the WHO classification. Univariate and multivariate regression analysis were performed using all clinical and pathological prognostic factors. All patients were treated with radiotherapy ⫹/- chemotherapy. Follow-up time is ranged between 12-80 months (Mean:32.2 months). Results: The histopathological diagnosis was WHO-I in one (1.3%), WHO-II in 15 (20.2%) and WHO-III in 58 (79.5%) patients. There were 38 (51%) patients with IL-10 expression and 44 patients with (61%) LMP-1 expression. Twenty-seven (36.4%) patients were found to be both IL-10 and LMP-1 positive. There were significantly more N0 disease in patients without LMP-1 expression compared to LMP-1 positive patients (65% vs. 35%, p⫽0.01). .The logistic regression analysis showed that advanced nodal involvement to be the major parameter effecting the expression of IL-10 (p⫽0.03). Three year overall survival (OS), locoregional relapse free survival (LRRFS) and distant metastasis free survival (DMFS) rates were 67.8%, 84.4% and 74.3%, respectively, for whole group. On univariate analysis, LRRFS was significantly lower in WHO-III patients, DMFS was significantly lower in advanced nodal disease and IL-10 negative patients and OS is significantly lower in WHO-III patients. Multivariate analysis showed that WHO-III and T2 patients were significantly associated with lower OS and N3 patients were significantly associated with lower DMFS. Conclusion: As a conclusion, we observed a high rate of (61%) EBV and NPC association in our patients. LMP-1 negative tumors were found to be less prone to invade lymph nodes. Patients without IL-10 expression has more advanced N disease. We did not find prognostic significant role of IL-10 and EBV LMP-1 on survival in multivariate analysis.
2021
Immunoconjugates of Catalase Attenuate Radiation-Induced Pulmonary Fibrosis in C57Bl Mice
M. Christofidou-Solomidou1, J. McDonough2, A. Scherpereel1, R. Wiewrodt1, E. Argyris1, C.C. Solomides1, S.M. Albelda1, V.R. Muzykantov1, M. Machtay2 1 Pulmonary Medicine, University of Pennsylvania, Philadelphia, PA, 2Radiation Oncology, University of Pennsylvania, Philadelphia, PA Background/Purpose: We have previously shown that enzymes conjugated with antibodies to PECAM (platelet-endothelial cell adhesion molcule)accumulate preferentially in the pulmonary vascular endothelium after intravenous administration in mice. In this study, we evaluated whether vascular immunotargeting of anti-PECAM/catalase to the pulmonary endothelium could decrease radiation-induced pulmonary fibrosis. Materials and Methods: Three groups of C57Bl6 mice were irradiated with 13.5 Gy single fraction (prescribed to the midplane), administered by an orthovoltage irradiator, to the entire thorax. Fifteen minutes before radiation, one cohort of 12 mice (Group A) was given a single tail vein injection of anti-PECAM/ctalase. A second cohort (Group B) was given a single tail vein injection of a control IgG-catalase conjugate. Group C was irradiated without any pre-treatment. Mice were sacrificed at 4 months post-irradiation for analysis of lung weight, qualitative histopathologic analysis (trichrome staining), and hydroxyproline content (a quantitative measure of fibrosis). Results: Hydroxyproline content for Groups A, B, and C was 2028 ⫾ 117 ng/g, 1356 ⫾ 232 ng/g, and 2633 ⫾ 152 ng/g. In comparison with Group C (irradiated controls not given any pre-treatment), hydroxyproline content was significantly lower in both Groups A (p ⫽0.012) and B (p ⬍0.0001). Hydroxyproline levels in groups A and B were similar to those seen in unirradiated control C57Bl6 mice. Histopathologic analysis showed that in anti-PECAM/catalase injected mice (Group A), the suppression of fibrosis was most prominent in the alveolar compartment. In contrast, in the IgG-catalase injected mice (Group B), the protection from fibrosis was localized to the peribronchial regions. Conclusion: Anti-PECAM/catalase and IgG-catalase conjugates can attenuate pulmonary fibrosis after large single fraction thoracic irradiation. The action of anti-PECAM/catalase appears to be more specific for the pulmonary microvasculature, the site of its targeting. Further animal studies are planned to validate and explore the therapeutic potential of vascular immunotargeting of catalase to pulmonary endothelium.
2022
A Novel Synthetic SuperOxide Dismutase Mimetic Manganese (III) Tetrakis (N-ethylpyridinium-2-yl) Porphyrin (MnIIITE-2-PyP5ⴙ) Protects Lungs from Radiation-Induced Injury
I. Batinic-Haberle1, I. Spasojevic1, I. Fridovich1, M.S. Anscher2, Z. Vujaskovic2 Biochemistry, Duke University Medical Center, Durham, NC, 2Radiation Oncology, Duke University Medical Center, Durham, NC 1
Purpose: A manganese porphyrin, MnIIITE-2-PyP5⫹, has been shown to offer a remarkable protection in the in vivo oxidative stress injury models such as stroke, diabetes, E. coli and others. The protective effects are based upon its in vitro chemical reactivities towards reactive oxygen (ROS) and nitrogen species (RNS) most so towards O2.-, NO. and their product peroxynitrite, ONOO -. The objectives of this study are to 1) kinetically and thermodynamically characterize MnIIITE-2-PyP5⫹ with respect to different ROS and RNS in order to understand its antioxidant activity and 2) to determine the radioprotective effect of MnIIITE-2-PyP5⫹ in the rat model of radiation-induced lung injury. Materials and Methods: Fisher-344 rats were irradiated to the right hemithorax using single dose of 28 Gy. MnIIITE-2-PyP5⫹ (6 mg/kg) was administrated i.p. before and during the first week after irradiation. Pulmonary function was assessed by measuring the changes in respiratory rate every two weeks for six months. TGF- levels in plasma were assessed monthly after treatment. Six months after irradiation animals were euthanized and lung tissue was processed for hydroxyproline content analysis, light microscopy and immunohistochemistry. Results: The rate constants for the reaction of Mn(III/II)TE-2-PyP5⫹/4⫹ with O2 .- are kMn(III) ⫽ 6.0 x 107 M-1 s-1,
235
I. J. Radiation Oncology
2018
● Biology ● Physics
Volume 51, Number 3, Supplement 1, 2001
Iododeoxyuridine (IdUrd)-Induced Cytotoxicity and Radiosensitivity Involves the Base Excision Repair (BER) Protein XRCC1
T.J. Kinsella, P. Taverna, H.S. Hwang, D. Zarling Radiation Oncology, University Hospitals of Cleveland, Cleveland, OH IdUrd is a halogenated thymidine analogue recognized as an effect IdUrd is a halogenated thymidine analogue recognized as an effect in vitro and in vivo radiosensitizer in human cancers. IdUrd-related cytotoxicity and/or radiosensitization were correlated with the extent of IdUrd-DNA incorporation replacing thymidine. The repair of intermediates including DNA Single Strand Breaks (SSB) and Double Strand Breaks (DSB) appears related to its cytotoxicity. Recently, we reported that DNA Mismatch Repair (MMR) deficient human tumor and murine cells show increased IdUrd-DNA incorporation and enhanced radiosensitization compared to geneticallymatched, MMR-proficient cells (Cancer Res. 59:1840-1845, 1999; Cancer Res. 60:5773-5780, 2000). As the thymidine analogue would not be expected to form DNA mismatches, we questioned whether Base Excision Repair (BER) might be responsible, in part, for our observations. To directly assess the role of BER in IdUrd cytotoxicity and radiosensitization, we used genetically-matched CHO cells, with (AA8 cells) and without (EM9 cells) XRCC1 expression. XRCC1 plays a central role in processing and repairing SSB and DSB. We found that EM9 cells were significantly more sensitive than parental AA8 cells to IdUrd alone (10-fold as IC50) and to IdUrd ⫹ Ionizing Radiation (⬎ 1 log at 1 M IdUrd and ⬎ 2 log at 3 M IdUrd). EM9 cells transfected with a cosmid vector carrying the human XRCC1 gene, showed responses to IdUrd similar to AA8 cells. Levels of IdUrd-DNA incorporation in EM9, AA8 and the transfected EM9 cells were identical following drug treatment. However, enhanced DNA damage was only found in EM9 cells as measured by pulse field gel electrophoresis. These data suggest that XRCC1-mediated BER participates in the “repair” of IdUrd-modified DNA and the inhibition of BER potentiates IdUrd-mediated radiosensitization.
2019
2-Deoxy-d-Glucose is a Cytotoxic and Radiosensitizing Agent in Tumor Cells
1
X. Lin , R. Aft2, D.R. Spitz3, D. Gius1 1 Section of Cancer Biology, Radiation Oncology Center, Washington University, St. Louis, MO, 2Department of Surgery, Washington University, St. Louis, MO, 3Free Radical and Radiation Biology Program, University of Iowa, Iowa City, IA Purpose: It is a well-established observation that tumor cells demonstrate altered metabolism when compared to normal, non-transformed cells. The most common alteration involves intracellular glucose utilization and the loss of regulation of glycolytic metabolism and respiration. This unique property of cancer cells has been utilized in cancer imaging and in researches of cancer treatment. Glucose deprivation was recently shown to selectively induce cell death via oxidative stress, and transformed cells responds to glucose deprivation differently than normal cells (J. Biol. Chem. 273:5294-5299; Ann. NY Acad. Sci. 899:349-362). 2-Deoxy-d-glucose (2-DG), a competitive glucose analog, is a potent inhibitor of glycolytic metabolism. 2-DG has been shown to inhibit growth of experimental mouse and rat tumors. Based on these observations, we hypothesized that 2-DG may also be cytotoxic via a mechanism involving oxidative stress; furthermore 2-DG may be a potential radiosensitizer since oxidative stress is one possible mechanism for ionizing radiation induced cell death. Materials and Methods: All cells were maintained in standard growth environment. A normal rat fibroblast cell line (208F) and its v-fos gene transformed counterpart (FBJ/R) are gifts from Dr. T. Curran at St. Jude Children’s Research Hospital, Memphis, TN. Twenty-four hours prior to drug treatment, cells were seeded at appropriate density in T-25 flasks. At the beginning of drug treatment, 2DG (final concentration of 4-10 mM) or N-acetylcysteine (NAC, final concentration 30 mM) was added to each flask containing 5 ml of fresh warmed medium and 1.5-2 x 106 cells. The total length of drug treatment varied from 0–72 hours. Cells were irradiated at the end of drug treatment. Fractional cell survival was evaluated by the standard colony forming assay. Results: When HeLa cells were treated with 2-DG, cell survival decreased to various degrees (0.9 to 0.1) depending on the drug concentration (4-10 mM) and length of treatment (4-72 h). When HeLa cells were treated with 2-DG (6 mM, 16 h) before exposure to ionizing radiation, their radiosensitivity were increased by a factor of 1.4 at the 50% isosurvival level, or 1.3 at the 10% isosurvival level. Treatment with a thiol antioxidant, NAC, protected HeLa cells against the cytotoxic effects of 6 mM 2-DG for up to 16 hours. In addition, treatment with NAC diminished the radiosensitization from 2-DG. The above results suggested a use for 2-DG. However, if 2-DG is to be of clinical significance, there has to be a greater cytotoxic effect on tumor versus normal cells. Thus we tested 2-DG on normal (208F) and matched transformed (FBJ/R) rat fibroblasts. At 6 mM of 2-DG, survival for the transformed FBJ/R cells was 0.85, 0.53, 0.21, after 4, 8, 24h of drug treatment, compared with 0.95, 0.75, 0.41 for the 208F cells. Additionally, the radiosensitizing effect of 2-DG was more pronounced in FBJ/R cells. At 2 Gy, 2-DG treatment (6 mM, 4 h) increased the radiosensitivity by a factor of 1.31 for FBJ/R cells, and only 1.08 for 208F cells. Conclusion: The results of these experiments demonstrate that 2-DG is a cytotoxic, as well as a radiosensitizating agent via a mechanism involving changes in intracellular oxidation/reduction status. Since tumor cells have altered glucose metabolism, it seems logical that tumor cells would be more sensitive to 2-DG. The above results with normal and matched transformed rat fibroblasts appear to validate a differential cytotoxic and radiosensitizing effects of 2-DG between normal and transformed cells, and suggest a possible clinical usefulness for 2-DG. This work is currently being pursued in mice xenograph experiments. (Supported by CA72602, ACS-IRG-58-010-43, and HL51469).
2020
Prognostic Role of Ebstein Barr Virus Latent Membrane Protein-1 and Interleukin-10 Expression in Patients with Nasopharyngeal Carcinoma
A.F. Korcum, E. Ozyar, A. Ayhan, I.L. Atahan Radiation Oncology, Hacettepe University, Ankara, Turkey Purpose: We aimed to investigate Ebtein Barr Virus (EBV) Latent Membran Protein-1 (LMP-1) and Interleukin-10 (IL-10) expression in 74 nasopharyngeal carcinoma (NPC) patients and to evaluate their prognostic significance. Material and Methods: Between 1993 and 1999, 144 patients were treated with the diagnosis of non-metastatic NPC at our
Proceedings of the 43rd Annual ASTRO Meeting
department. The expression of LMP-1 and IL-10 was investigated by using immunohistochemical approach in 74 (53 male, 21 female) patients whose paraffin embedded tissue samples were obtained. A detailed histopathological analysis including degree of apoptosis and lymphocyte infiltration was made and all patients were reclassified according to the WHO classification. Univariate and multivariate regression analysis were performed using all clinical and pathological prognostic factors. All patients were treated with radiotherapy ⫹/- chemotherapy. Follow-up time is ranged between 12-80 months (Mean:32.2 months). Results: The histopathological diagnosis was WHO-I in one (1.3%), WHO-II in 15 (20.2%) and WHO-III in 58 (79.5%) patients. There were 38 (51%) patients with IL-10 expression and 44 patients with (61%) LMP-1 expression. Twenty-seven (36.4%) patients were found to be both IL-10 and LMP-1 positive. There were significantly more N0 disease in patients without LMP-1 expression compared to LMP-1 positive patients (65% vs. 35%, p⫽0.01). .The logistic regression analysis showed that advanced nodal involvement to be the major parameter effecting the expression of IL-10 (p⫽0.03). Three year overall survival (OS), locoregional relapse free survival (LRRFS) and distant metastasis free survival (DMFS) rates were 67.8%, 84.4% and 74.3%, respectively, for whole group. On univariate analysis, LRRFS was significantly lower in WHO-III patients, DMFS was significantly lower in advanced nodal disease and IL-10 negative patients and OS is significantly lower in WHO-III patients. Multivariate analysis showed that WHO-III and T2 patients were significantly associated with lower OS and N3 patients were significantly associated with lower DMFS. Conclusion: As a conclusion, we observed a high rate of (61%) EBV and NPC association in our patients. LMP-1 negative tumors were found to be less prone to invade lymph nodes. Patients without IL-10 expression has more advanced N disease. We did not find prognostic significant role of IL-10 and EBV LMP-1 on survival in multivariate analysis.
2021
Immunoconjugates of Catalase Attenuate Radiation-Induced Pulmonary Fibrosis in C57Bl Mice
M. Christofidou-Solomidou1, J. McDonough2, A. Scherpereel1, R. Wiewrodt1, E. Argyris1, C.C. Solomides1, S.M. Albelda1, V.R. Muzykantov1, M. Machtay2 1 Pulmonary Medicine, University of Pennsylvania, Philadelphia, PA, 2Radiation Oncology, University of Pennsylvania, Philadelphia, PA Background/Purpose: We have previously shown that enzymes conjugated with antibodies to PECAM (platelet-endothelial cell adhesion molcule)accumulate preferentially in the pulmonary vascular endothelium after intravenous administration in mice. In this study, we evaluated whether vascular immunotargeting of anti-PECAM/catalase to the pulmonary endothelium could decrease radiation-induced pulmonary fibrosis. Materials and Methods: Three groups of C57Bl6 mice were irradiated with 13.5 Gy single fraction (prescribed to the midplane), administered by an orthovoltage irradiator, to the entire thorax. Fifteen minutes before radiation, one cohort of 12 mice (Group A) was given a single tail vein injection of anti-PECAM/ctalase. A second cohort (Group B) was given a single tail vein injection of a control IgG-catalase conjugate. Group C was irradiated without any pre-treatment. Mice were sacrificed at 4 months post-irradiation for analysis of lung weight, qualitative histopathologic analysis (trichrome staining), and hydroxyproline content (a quantitative measure of fibrosis). Results: Hydroxyproline content for Groups A, B, and C was 2028 ⫾ 117 ng/g, 1356 ⫾ 232 ng/g, and 2633 ⫾ 152 ng/g. In comparison with Group C (irradiated controls not given any pre-treatment), hydroxyproline content was significantly lower in both Groups A (p ⫽0.012) and B (p ⬍0.0001). Hydroxyproline levels in groups A and B were similar to those seen in unirradiated control C57Bl6 mice. Histopathologic analysis showed that in anti-PECAM/catalase injected mice (Group A), the suppression of fibrosis was most prominent in the alveolar compartment. In contrast, in the IgG-catalase injected mice (Group B), the protection from fibrosis was localized to the peribronchial regions. Conclusion: Anti-PECAM/catalase and IgG-catalase conjugates can attenuate pulmonary fibrosis after large single fraction thoracic irradiation. The action of anti-PECAM/catalase appears to be more specific for the pulmonary microvasculature, the site of its targeting. Further animal studies are planned to validate and explore the therapeutic potential of vascular immunotargeting of catalase to pulmonary endothelium.
2022
A Novel Synthetic SuperOxide Dismutase Mimetic Manganese (III) Tetrakis (N-ethylpyridinium-2-yl) Porphyrin (MnIIITE-2-PyP5ⴙ) Protects Lungs from Radiation-Induced Injury
I. Batinic-Haberle1, I. Spasojevic1, I. Fridovich1, M.S. Anscher2, Z. Vujaskovic2 Biochemistry, Duke University Medical Center, Durham, NC, 2Radiation Oncology, Duke University Medical Center, Durham, NC 1
Purpose: A manganese porphyrin, MnIIITE-2-PyP5⫹, has been shown to offer a remarkable protection in the in vivo oxidative stress injury models such as stroke, diabetes, E. coli and others. The protective effects are based upon its in vitro chemical reactivities towards reactive oxygen (ROS) and nitrogen species (RNS) most so towards O2.-, NO. and their product peroxynitrite, ONOO -. The objectives of this study are to 1) kinetically and thermodynamically characterize MnIIITE-2-PyP5⫹ with respect to different ROS and RNS in order to understand its antioxidant activity and 2) to determine the radioprotective effect of MnIIITE-2-PyP5⫹ in the rat model of radiation-induced lung injury. Materials and Methods: Fisher-344 rats were irradiated to the right hemithorax using single dose of 28 Gy. MnIIITE-2-PyP5⫹ (6 mg/kg) was administrated i.p. before and during the first week after irradiation. Pulmonary function was assessed by measuring the changes in respiratory rate every two weeks for six months. TGF- levels in plasma were assessed monthly after treatment. Six months after irradiation animals were euthanized and lung tissue was processed for hydroxyproline content analysis, light microscopy and immunohistochemistry. Results: The rate constants for the reaction of Mn(III/II)TE-2-PyP5⫹/4⫹ with O2 .- are kMn(III) ⫽ 6.0 x 107 M-1 s-1,
235