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Arginase 1 (A1) is the enzyme that hydrolyzes the amino acid, L-arginine, to ornithine and urea. We have previously shown that A1 deletion worsens retinal ischemic injury, suggesting a protective role of A1. In this translational study, we aimed to study the utility of systemic pegylated A1 (PEG-A1, recombinant human arginase linked to polyethylene glycol) treatment in mouse models of acute retinal and brain injury. Cohorts of WT mice were subjected to retinal ischemia-reperfusion (IR) injury, traumatic optic neuropathy (TON) or brain cerebral ischemia via middle cerebral artery occlusion (MCAO) and treated with intraperitoneal injections of PEG-A1 or vehicle (PEG only). Drug penetration into retina and brain tissues was measured by western blotting and immunolabeling for PEG. Neuroprotection was measured in a blinded fashion by quantitation of NeuN (neuronal marker) immunolabeling of retina flat-mounts and brain infarct area using triphenyl tetrazolium chloride (TTC) staining. Furthermore, ex vivo retina explants and in vitro retina neuron cultures were subjected to oxygen-glucose deprivation (OGD) followed by reoxygenation (R) and treated with PEG-A1. PEG-A1 given systemically did not cross the intact blood-retina/brain barriers in sham controls but reached the retina and brain after injury. PEG-A1 provided neuroprotection after retinal IR injury, TON and cerebral ischemia. PEG-A1 treatment was also neuroprotective in retina explants subjected to OGD/R but did not improve survival in retinal neuronal cultures exposed to OGD/R. In summary, systemic PEG-A1 administration is neuroprotective and provides an excellent route to deliver the drug to the retina and the brain after acute injury.

Background Bladder cancer is one of the dominant cancers worldwide, especially for male. Currently, the therapeutical regimen of bladder cancer is based on surgery, radiation therapy, chemotherapy and immunotherapy, but the clinical outcome is still needed to improve. Recombinant human arginase (rhArg, BCT-100) is a novel agent to show great anticancer effect on arginine auxotrophic tumor. However, the effect of rhArg on bladder cancer still remains unclear. Methods A panel of six bladder cancer cell lines (BIU-87, EJ-1, J82, SCaBER, T24 and 5637) was employed to assess the anticancer effect of BCT-100 in vitro by MTT assay. T24 nude mice xenograft models were established to evaluate the anticancer effect of BCT-100 in vivo. Protein level (argininosuccinate synthetase 1 (ASS1), ornithine transcarbamylase, cleaved-PARP, PEG, Survivin, p62, Beclin-1, LC3B, p-AKT, p-mTOR) was detected by Western blot. Intracellular, serum and intratumoral arginine concentrations were examined by ELISA. Apoptotic rate, H2O2 and mitochondrial membrane depolarization were tested by flow cytometer. Immunoflorescence on ki67 and TUNEL assay were applied to identify cellular and tumoral apoptotic events. Results BCT-100 displayed anticancer effects on bladder cancer cells in vitro and in vivo. The expression of ASS1 varies in different bladder cancer cell lines, and ornithine transcarbamylase is almost deficient except weakly expressed in SCaBER cell line. Knockdown ASS1 in BIU-87 cells could enhance the cytotoxicity induced by BCT-100. Intracellular arginine level was sharply decreased followed by apoptotic events. Futhermore, BCT-100 induced H2O2 production and mitochondrial membrane depolarization, leading to cytochrome c and smac released from mitochondria to cytosol. The expression of LC3B and Becllin-1 was up-regulated, while p62 was down-regulated in a time dependent manner. Autophagic flux was also observed upon BCT-100 treatment. Besides, the phosphorylation of AKT/mTOR pathway was suppressed in a time dependent fashion in BCT-100-treated T24 cells. N-Acetyl-L-cystein reduced the apoptosis and autophagy induced by BCT-100, while CQ, MK-2206 and rapamycin potentiated the apoptosis triggered by BCT-100. Conclusions The present study demonstrated that BCT-100 induced autophagy and apoptosis via ROS mediated AKT/mTOR signaling pathway in bladder cancer cells.

Depletion of arginine induced by PEGylated arginase 1 (ARG1) (BCT-100) has shown anticancer effects in arginine auxotrophic cancers that lack argininosuccinate synthetase (ASS1) and ornithine transcarbamylase (OTC). High levels of endogenous arginase 2 (ARG2) have been previously reported in human lung cancers. Although a high-ARG2 level neither causes immunosuppression nor affects disease progression, it may theoretically affect the efficacy of PEGylated ARG1 treatment. ARG2 was shown to be highly expressed in H520 squamous cell lung carcinoma (lung SCC) xenografts but undetectable in SK-MES-1 and SW900 lung SCC xenografts. We propose that high-endogenous expression of ARG2 could impede the anti-tumor effect of PEGylated ARG1 in lung SCC. The in vivo effect of PEGylated ARG1 was investigated using three xenograft models of lung SCC. PEGylated ARG1 (60 mg/kg) suppressed tumor growth in SK-MES-1 and SW900 but not H520 xenografts. ASS1 was expressed in SK-MES-1 and SW900 xenografts while OTC expression remained low in all xenografts. A high-endogenous ARG2 level was detected only in H520 xenografts. Serum arginine level was decreased significantly by PEGylated ARG1 in all xenografts. Nonetheless intratumoral arginine level was decreased by PEGylated ARG1 in SK-MES-1 and SW900, not H520 xenografts. In SK-MES-1 xenografts, PEGylated ARG1 treatment induced G1 arrest, downregulation of Ki67 and Mcl-1 and activation of apoptosis. In SW900 xenografts, upregulation of Bim and activation of apoptosis were observed upon PEGylated ARG1 treatment. Silencing of ARG2 re-sensitized the H520 xenografts to PEGylated ARG1 treatment, partially mediated through arginine depletion via G1 arrest and apoptosis. PEGylated ARG1 treatment (BCT-100) was effective in lung SCC xenografts with low-endogenous levels of ASS1/OTC and ARG2. High-endogenous ARG2 expression may cause resistance to PEGylated ARG1 treatment in lung SCC xenografts. ARG2 may serve as a third predictive biomarker in PEGylated ARG1 treatment in lung SCC.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a difficult-to-treat global disease. Pegylated arginase (BCT-100) has recently shown anti-tumor effects in hepatocellular carcinoma, acute myeloid leukemia and melanoma. This study aims to investigate the effects of PEG-BCT-100 in MPM. METHODS: A panel of 5 mesothelioma cell lines (H28, 211H, H226, H2052 and H2452) was used to study the in vitro effects of BCT-100 by crystal violet staining. The in vivo effects of BCT-100 were studied using 211H and H226 nude mice xenografts. Protein expression (argininosuccinate synthetase, ornithine transcarbamylase, cleaved PARP, cleaved caspase 3, cyclins (A2, D3, E1 and H), CDK4 and Ki67) and arginine concentration were evaluated by Western blot and ELISA respectively. Cellular localization of BCT-100 was detected by immunohistochemistry and immunoflorescence. TUNEL assay was used to identify cellular apoptotic events. RESULTS: Argininosuccinate synthetase was expressed in H28, H226, and H2452 cells as well as 211H and H266 xenografts. Ornithine transcarbamylase was undetectable in all cell lines and xenograft models. BCT-100 reduced in vitro cell viability (IC50 values at 13-24 mU/ml, 72 h) across different cell lines and suppressed tumor growth in both 211H and H226 xenograft models. BCT-100 (60 mg/kg) significantly suppressed tumor growth (p, published_or_final_version

e20538Background: Arginine depletion induced by PEGylated arginase 1 (BCT-100, PEG-BCT-100 or rhArg1peg5000) has shown promising anticancer effects among arginine auxotrophic cancers that are defic...

POSTER SESSION 3 – P3.03: Mesothelioma/Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies

e20083Background: Cancers with deficient argininosuccinate synthetase (ASS) and/or ornithine transcarbamylase (OTC) are biologically vulnerable to arginine depletion. Preliminary clinical data had ...

e15137 Background: This study was designed to evaluate the efficacy, safety profile, pharmacokinetics/pharmacodynamics (PK/PD) and quality of life (QoL) of pegylated recombinant human arginase 1(Pe...

Cell-based polygonal isosurface generation is a common and useful technique for visualizing sampled scalar fields. Typically, however, the number of polygons in the surface model can become quite large as the size of the data set increases. In this paper, we present octree pruning techniques designed to compress the isosurface model while maintaining an accurate representation. We show results for several data sets, and demonstrate speed improvements of over two orders of magnitude over our previous results. A key feature of this work is the use of a volumetric error criterion to quantify model accuracy.

Volume rendering techniques typically process volumetric data in raw, uncompressed form. As algorithmic and architectural advances improve rendering speeds, however, larger data sets will be evaluated requiring consideration of data storage and transmission issues. In this paper, we analyze the data compression requirements for volume rendering applications and present a solution based on vector quantization. The proposed system compresses volumetric data and then renders images directly from the new data format. Tests on a fluid flow data set demonstrate that good image quality may be achieved at a compression ratio of 17:1 with only a 5 percent cost in additional rendering time.