Keun Sik Kim

Proteasome inhibitors with pyrazole scaffolds from structure-based virtual screening.

We performed a virtual screen of ∼340u202f000 small molecules against the active site of proteasomes followed by in vitro assays and subsequent optimization, yielding a proteasome inhibitor with pyrazole scaffold. The pyrazole-scaffold compound displayed excellent metabolic stability and was highly effective in suppressing solid tumor growth in vivo. Furthermore, the effectiveness of this compound was not negatively impacted by resistance to bortezomib or carfilzomib.

Inhibition of angiogenesis by salmosin expressed in vitro.

Recently, salmosin, a novel snake venom-derived disintegrin containing the Arg-Gly-Asp (RGD) sequence, was reported to be both antiangiogenic and antitumorigenic. The antitumor activity was substantiated by in vivo administration of recombinant salmosin into mice bearing tumors. However, it was difficult to prepare functionally active recombinant salmosin and to maintain a therapeutically effective concentration of the protein in the circulatory system by daily injections. Hence, we have suggested that salmosin gene transfer mediated by cationic liposomes may be a practical alternative for cancer treatment. Plasmids encoding the salmosin gene were constructed and then transferred by means of cationic liposomes into transformed human embryonic kidney (HEK) 293 cells. The transfected genes were able to produce functionally active salmosin proteins in vitro. In fact, the expressed salmosin remarkably inhibited proliferation of bovine capillary endothelial (BCE) cells and effectively inhibited the migration of highly metastatic B16BL6 mouse melanoma cells. Neovascularization in chick chorio-allantoic membranes (CAM) and in Matrigel implanted subcutaneously into mice was greatly inhibited in the presence of the expressed salmosin. Based on these experimental results, we suggest that the antitumor effect induced by salmosin gene transfection may be due to the antiangiogenic activity of the expressed salmosin proteins.

Antitumor effects of angiostatin K1-3 and endostatin genes coadministered by the hydrodynamics-based transfection method.

Angiostatin and endostatin are potent endothelial cell growth inhibitors and have been carefully evaluated for antiangiogenic cancer therapy. Previously, we have shown that subcutaneous administration of angiostatin K1-3 and endostatin genes complexed with liposomal vectors is a more practical treatment procedure than administration of angiostatin and endostatin proteins. This study provides additional conclusive evidence supporting the effectiveness of antiangiogenic cancer gene therapy employing angiostatin K1-3 and endostatin genes. Plasmids encoding a mouse angiostatin K1-3 gene (pFLAG-AngioK1/3) and an endostatin gene (pFLAG-Endo) were introduced by the hydrodynamic transduction method into mice carrying Matrigel plugs or B16BL6 mouse melanoma tumors. A single systemic injection of the two genes exhibited potent antiangiogenic and antitumor activity in the mouse model. Hydrodynamic coadministration of the genes inhibited the B16BL6 mouse melanoma growth and pulmonary metastasis more effectively than administration of either gene alone. Compared with the untreated control group, the mice cotreated with pFLAG-AngioK1/3 and pFLAG-Endo exhibited 75% reduction of tumor growth while those treated with pFLAG-AngioK1/3 or pFLAG-Endo showed 46% and 52% reduction, respectively. The cotreatment inhibited B16BL6 pulmonary metastasis formation by 80% while the inhibition induced by individual treatment with pFLAG-AngioK1/3 or pFLAG-Endo was 68% and 71%, respectively. These results provide additional evidence that systemic expression of angiostatin K1-3 and/or endostatin genes is a viable alternative procedure for antiangiogenic cancer therapy.

Synergistic antitumoral effect of IL-12 gene cotransfected with antiangiogenic genes for angiostatin, endostatin, and saxatilin.

Previously, it was reported that the cotransfection of angiostatin K1-3, endostatin, and saxatilin genes using cationic liposomes significantly inhibited tumor progression. IL-12 is a well-known immune modulator that promotes Th1-type antitumor immune responses and also induces antiangiogenic effects. In this study, we have examined the antitumoral function of the IL-12 gene cotransfected with antiangiogenic genes for angiostatin K1-3, endostatin, and saxatilin by O,O-dimyristyl-N-lysyl glutamate (DMKE) cationic liposomes in a mouse tumor model. According to our results, the administration of the IL-12 gene or the genes for angiostatin K1-3, endostatin, and saxatilin exhibited effective inhibition of B16BL6 melanoma growth in mice. In particular, intravenous administration of the IL-12 gene along with intratumoral administration of the three antiangiogenic genes synergistically inhibited the B16BL6 tumor growth. These results suggest that systemically expressed IL-12 enhances antitumoral efficacy of locally expressed antiangiogenic proteins.

Sendai viroplexes for epidermal growth factor receptor-directed delivery of interleukin-12 and salmosin genes to cancer cells.

The effective delivery of therapeutic genes to target cells has been a fundamental goal in cancer gene therapy because of its advantages with respect to both safety and transfection efficiency. In the present, study we describe a tumor‐directed gene delivery system that demonstrates remarkable efficacy in gene delivery and minimizes the off‐target effects of gene transfection.

Sendai Viroplexes for EGF Receptor‐directed Delivery of IL12 and Salmosin Genes to Cancer Cells

The effective delivery of therapeutic genes to target cells has been a fundamental goal in cancer gene therapy because of its advantages with respect to both safety and transfection efficiency. In the present, study we describe a tumor‐directed gene delivery system that demonstrates remarkable efficacy in gene delivery and minimizes the off‐target effects of gene transfection.

Sendai F/HN viroplexes for efficient transfection of leukemic T cells.

Purpose Most chemical transfection reagents are ineffective for the transfection of cells in suspension, such as leukemic cell and stem cell lineages. We developed two different types of viroplexes, cationic Sendai F/HN viroplexes (CSVs) and protamine sulfate-condensed cationic Sendai F/HN viroplexes (PCSVs) for the efficient transfection of T-leukemic cells. Materials and Methods The viroplex systems were prepared by reconstitution of fusogenic Sendai F/HN proteins in DMKE (O,O-dimyristyl-N-lysyl glutamate) cationic liposomes. The viroplexes were further optimized for plasmid DNA and siRNA delivery to suspension cells. The particle size and surface charge of the viroplexes were analyzed with a ζ-sizer. Transfection of plasmid DNA (pDNA) and small interfering RNA (siRNA) by CSVs or PCSV was evaluated by measurement of transgene expression, confocal microscopy, FACS, and RT-PCR. Results The optimized CSVs and PCSVs exhibited enhanced gene and siRNA delivery in the tested suspension cell lines (Jurkat cells and CEM cells), compared with conventional cationic liposomes. In the case of pDNA transfection, the CSVs and PCSVs show at least 10-fold and 100-fold higher transgene expression compared with DMKE lipoplexes (or lipofectamine 2000), respectively. The CSVs showed more effective siRNA delivery to the suspension cells than cationic liposomes, as assessed by confocal microscopy, FACS, and RT-PCR. The effective transfection by the CSVs and PCSVs is presumably due to fusogenic activity of F/HN proteins resulting in facilitated internalization of pDNA and siRNA. Conclusion This study suggests that Sendai F/HN viroplexes can be widely applicable for the transfection of pDNA and siRNA to suspension cell lines.

Tumor-specific delivery of therapeutic siRNAs by anti-EGFR immunonanoparticles

Background Efficient target-specific siRNA delivery has always been a primary concern in the field of siRNA clinical application. Purpose In this study, four different types of anti-epidermal growth factor receptor (EGFR) antibody-conjugated immunonanoparticles were prepared and tested for cancer cell-targeted therapeutic siRNA delivery. Materials and methods The prepared nanoparticles encapsulating siRNAs were character-ized by gel retardation and particle analysis using a Zetasizer. In vitro transfection and reduction of target genes, vimentin and JAK3, were determined using quantitative reverse transcription polymerase chain reaction. In vivo tumor targeting and antitumoral efficacies of the nanoparticles were evaluated in mice carrying tumors. Results Among these immunonanoparticles, anti-EGFR immunolipoplexes and immunoviroplexes exhibited remarkable cell binding and siRNA delivery to EGFR-expressing tumor cells compared to immunoliposomes and immunovirosomes. Especially, the anti-EGFR immunoviroplexes exhibited the most efficient siRNA transfection to target tumor cells. Therefore, antitumoral vimentin and Janus kinase-3 siRNAs were loaded in the anti-EGFR immunolipoplexes and immunoviroplexes, which were tested in mice carrying SK-OV-3 tumor xenografts. In fact, the therapeutic siRNAs were efficiently delivered to the tumor tissues by both delivery vehicles, resulting in significant inhibition of tumor growth. Moreover, administration of doxorubicin in combination with anti-EGFR immunoviroplexes resulted in remarkable and synergistic tumor growth inhibition. Conclusion This study provides experimental proof that cancer cell-targeted immunoviroplexes are an efficient siRNA delivery system for cancer therapy. Moreover, this study also suggests that a combination of conventional chemotherapy and tumor-directed anticancer siRNA therapy would be a better modality for cancer treatment.

Anti-EGFR immunonanoparticles containing IL12 and salmosin genes for targeted cancer gene therapy

Tumor-directed gene delivery is of major interest in the field of cancer gene therapy. Varied functionalizations of non-viral vectors have been suggested to enhance tumor targetability. In the present study, we prepared two different types of anti-EGF receptor (EGFR) immunonanoparticles containing pDNA, neutrally charged liposomes and cationic lipoplexes, for tumor-directed transfection of cancer therapeutic genes. Even though both anti-EGFR immunonanoparticles had a high binding affinity to the EGFR-positive cancer cells, the anti-EGFR immunolipoplex formulation exhibited approximately 100-fold higher transfection to the target cells than anti-EGFR immunoliposomes. The lipoplex formulation also showed a higher transfection to SK-OV-3 tumor xenografts in mice. Thus, IL12 and/or salmosin genes were loaded in the anti-EGFR immunolipoplexes and intravenously administered to mice carrying SK-OV-3 tumors. Co-transfection of IL12 and salmosin genes using anti-EGFR immunolipoplexes significantly reduced tumor growth and pulmonary metastasis. Furthermore, combinatorial treatment with doxorubicin synergistically inhibited tumor growth. These results suggest that anti-EGFR immunolipoplexes containing pDNA encoding therapeutic genes could be utilized as a gene-transfer modality for cancer gene therapy.