Knockdown of COPA, Identified by Loss-of-Function Screen, Induces Apoptosis and Suppresses Tumor Growth in Mesothelioma Mouse Model

AbstractMalignant mesothelioma is a highly aggressive tumor arising from serosal surfaces of the pleura and is triggered by past exposure to asbestos. Currently, there is no widely accepted treatment for mesothelioma. Development of effective drug treatments for human cancers requires identification of therapeutic molecular targets. We therefore conducted a large-scale functional screening of mesothelioma cells using a genome-wide small interfering RNA library. We determined that knockdown of 39 genes suppressed mesothelioma cell proliferation. At least seven of the 39 genes—COPA, COPB2, EIF3D, POLR2A, PSMA6, RBM8A, and RPL18A—would be involved in anti-apoptotic function. In particular, the COPA protein was highly expressed in some mesothelioma cell lines but not in a pleural mesothelial cell line. COPA knockdown induced apoptosis and suppressed tumor growth in a mesothelioma mouse model. Therefore, COPA may have the potential of a therapeutic target and a new diagnostic marker of mesothelioma

Anticancer Effect of Dihydroartemisinin (DHA) in a Pancreatic Tumor Model Evaluated by Conventional Methods and Optical Imaging

Background: Dihydroartemisinin (DHA) inhibits the growth of certain cancer cells and xenograft tumors. Further understanding of the molecular mechanisms and genetic participants that govern the antineoplastic effects of DHA is necessary. The anticancer effects of DHA and its underlying mechanisms in pancreatic cancer and the efficacy in animal models by noninvasive optical imaging were evaluated. Materials and Methods: Combined with cell/tumor growth assays, flow cytometric analysis, and Hoechst staining, the effect of DHA was investigated using the pancreatic cancer cell line BxPc3-RFP stably expressing red fluorescence protein and in vitro/in vivo optical imaging. Proteins that regulate proliferation (PCNA), apoptosis (Bax and Bcl-2), and angiogenesis (vascular endothelial growth factor (VEGF)) were evaluated in cell and tumor samples by Western blotting and immunohistochemical analyses. Results: DHA inhibited the proliferation and viability of cells in a dose-dependent manner and induced apoptosis. We observed down-regulation of PCNA and Bcl-2, and up-regulation of Bax. VEGF was down-regulated by DHA in cells under normoxic, but not hypoxic, conditions. Fluorescence intensity emitted from cells and tumors correlated linearly with cell count and tumor burden, respectively. Conclusion: DHA inhibits cell and tumor growth by interfering with cell proliferation and inducing apoptosis. The antiangiogenic effect of DHA appears to be a complicated process. Optical imaging supports the real-time assessment of DHA efficacy in a preclinical model and comprehensive analysis substantiates that DHA is a potential candidate for pancreatic cancer therapy

Assessment and Evaluation of the Anticancer Effect of Dihydroartemisinin (DHA) in a Pancreatic Tumor Model by Conventional Methods and Optical Imaging

Objective: Dihydroartemisinin (DHA), an active derivative of artemisinin which is now recognized as antimalarial drug, inhibits the growth of certain cancer cells and xenograft tumors. Further understanding of the molecular mechanisms and genetic participants that govern the antineoplastic effects of DHA is necessary. The anticancer effects of DHA and its underlying mechanisms in pancreatic cancer and the efficacy in animal models by noninvasive optical imaging, a suitable technique for real-time characterization of the therapeutic effects on tumor, were evaluated. Materials and Methods: Combined with conventional methods such as cell/tumor growth assays, flow cytometric analysis, and Hoechst staining for apoptosis, the effect of DHA was confirmed using the pancreatic cancer cell line BxPc3-RFP stably expressing red fluorescence protein and in vitro/in vivo optical imaging. Proteins that regulate proliferation (proliferating cell nuclear antigen (PCNA)), apoptosis (Bax and Bcl-2), and angiogenesis (vascular endothelial growth factor (VEGF)) were evaluated in cell and tumor samples by Western blotting and immunohistochemical analyses. Results: DHA inhibited the proliferation and viability of cells in a dose-dependent manner and induced apoptosis. We observed down-regulation of PCNA and Bcl-2, and up-regulation of Bax. VEGF was down-regulated by DHA in cells under normoxic, but not hypoxic, conditions. Fluorescence intensity emitted from cells and tumors correlated linearly with cell count and tumor burden, respectively. Conclusion: DHA inhibits cell and tumor growth by interfering with cell proliferation and inducing apoptosis. The antiangiogenic effect of DHA may be partial and appears to be a complicated process. Optical imaging allows convenient and reliable real-time evaluation of DHA efficacy in a preclinical model and comprehensive analysis substantiates that DHA is a potential candidate for pancreatic cancer therapy.2011 World Molecular Imaging Congress (WMIC

18F-FDG PET for Semiquantitative Evaluation of Acute Allograft Rejection and Immunosuppressive Therapy Efficacy in Rat Models of Liver Transplantation

Acute allograft rejection remains a major complication after liver transplantation. We report a semiquantitative imaging method of detecting acute allograft rejection with 18F-FDG PET. Methods: Syngeneic and allogeneic transplanted rats, with or without immunosuppressive treatment, were subjected to serial PET. Autoradiography of the liver was conducted in both the syngeneic and the allogeneic rats. Results: A significant increment of 18F-FDG accumulation in liver allografts was observed byPET on day 2. The 18F-FDG signal was concentrated in the area where inflammatory cells around the vessels were detected by autoradiography. Allotransplanted rats treated with an immunosuppressive agent displayed a marked decrease in hepatic 18F-FDG uptake, compared with allotransplanted rats that were not treated. Conclusion: 18F-FDG PET may be a valid method for facilitating the development of protocols to diagnose graftrejection and to monitor the efficacy of immunosuppressive therapy