Chang Hoon Moon

Butyrate response factor 1 enhances cisplatin sensitivity in human head and neck squamous cell carcinoma cell lines

Cisplatin is a widely used chemotherapeutic agent in head and neck squamous cell carcinoma (HNSCC). Resistance to cisplatin is a common feature of HNSCC. To identify genes that may regulate cisplatin sensitivity, we carried out a cDNA microarray analysis of gene expression in cisplatin‐sensitive and cisplatin‐resistant HNSCC‐derived cell lines. Among genes differentially expressed by cisplatin treatment, we have confirmed the elevated expression of butyrate responsive factor 1 (BRF1) in cisplatin‐sensitive HNSCC cells and have demonstrated that the expression level of BRF1 is associated with cisplatin‐sensitivity. Specific inhibition of BRF1 expression using an antisense oligodeoxynucleotide (ODN) decreased the cisplatin‐sensitivity and, on the contrary, overexpression of BRF1 increased cisplatin‐sensitivity in HNSCC cells. Elevated expression of BRF1 decreased the level of the human inhibitor of apoptosis protein‐2 (cIAP2) and increased the caspase‐3 activity in HNSCC cells. In addition, elevated expression of BRF1 decreased the expression level of enhanced green fluorescent protein (EGFP) linked to a 3′ terminal AU‐rich element (ARE) of cIAP2 mRNA. These findings demonstrate that BRF1 expression enhanced cisplatin sensitivity in HNSCC cells by reducing the levels of cIAP2 mRNA.

Comparison of the immunogenicity of recombinant VP2 and VP3 of infectious pancreatic necrosis virus and marine birnavirus

Summary.Recombinant proteins of truncated viral protein-2 (VP2) (aa 79-359) and VP3 of infectious pancreatic necrosis virus (IPNV) and marine birnavirus (MABV) were expressed in E. coli and their immunogenicities in fish were investigated. The recombinant proteins from IPNV were used to immunize rainbow trout and those from MABV to immunize flounder. The sera from the immunized fishes were assayed for antibody by ELISA and a neutralization test. Both the recombinant VP2 and VP3 produced antibodies in fish but the VP3 antibody titers were higher than that of the VP2 of IPNV and MABV. These results indicate that the recombinant VP3 is more immunogenic than the re-combinant VP2.

Developmentally regulated GTP-binding protein 2 coordinates Rab5 activity and transferrin recycling.

The small GTPase Rab5 regulates the early endocytic pathway of transferrin (Tfn), and Rab5 deactivation is required for Tfn recycling. Developmentally regulated GTP-binding protein 2 is required for interaction between Rab5 and RabGAP5 on endosomes and acts as a key regulator for Rab5 deactivation and Tfn recycling.

KML001 Displays Vascular Disrupting Properties and Irinotecan Combined Antitumor Activities in a Murine Tumor Model

KML001 is sodium metaarsenite, and has shown cytotoxic activity in human tumor cell lines. The anti-cancer mechanism of KML001 involves cancer cell destruction due to DNA damage at the telomeres of cancer cell chromosomes. In this study, we assessed the vascular disrupting properties of KML001 and investigated whether KML001 as VDA is able to increase anti-tumor activity in irinotecan combined treatment. We used a murine model of the CT26 colon carcinoma cell line. CT26 isograft mice treated intraperitoneally with 10 mg/kg KML001 displayed extensive central necrosis of tumor by 24 h. The vascular disrupting effects of KML001 were assessed by dynamic contrast enhanced magnetic resonance imaging. Gadopentetic acid-diethylene triaminepentaacetic acid contrast enhancement was markedly decreased in KML001-treated mice one day after treatment, whereas persistently high signal enhancement was observed in mice injected with saline. Rate constant Kep value representing capillary permeability was significantly decreased (p<0.05) in mice treated with KML001. Cytoskeletal changes of human umbilical vein endothelial cells (HUVECs) treated with 10 uM KML001 were assessed by immune blotting and confocal imaging. KML001 degraded tubulin protein in HUVECs, which may be related to vascular disrupting properties of KML001. Finally, in the mouse CT26 isograft model, KML001 combined with irinotecan significantly delayed tumor growth as compared to control and irinotecan alone. These results suggest that KML001 is a novel vascular disrupting agent, which exhibits significant vascular shut-down activity and enhances anti-tumor activity in combination with chemotherapy. These data further suggest an avenue for effective combination therapy in treating solid tumors.

Arsenic trioxide induces depolymerization of microtubules in an acute promyelocytic leukemia cell line

Background Arsenic trioxide (As2O3) is a well-known and effective treatment that can result in clinical remission for patients diagnosed with acute promyelocytic leukemia (APL). The biologic efficacy of As2O3 in APL and solid tumor cells has been explained through its actions on anti-proliferation, anti-angiogenesis, and apoptotic signaling pathways. We theorize that As2O3 activates a pathway that disrupts microtubule dynamics forming abnormal, nonfunctioning mitotic spindles, thus preventing cellular division. In this study, we investigated how As2O3 induces apoptosis by causing microtubule dysfunction. Methods Cultured NB4 cells were treated with As2O3, paclitaxel, and vincristine. Flow cytometric analysis was then performed. An MTT assay was used to determine drug-mediated cytotoxicity. For tubulin polymerization assay, each polymerized or soluble tubulin was measured. Microtubule assembly-disassembly was measured using a tubulin polymerization kit. Cellular microtubules were also observed with fluorescence microscopy. Results As2O3 treatment disrupted tubulin assembly resulting in dysfunctional microtubules that cause death in APL cells. As2O3 markedly enhanced the amount of depolymerized microtubules. The number of microtubule posttranslational modifications on an individual tubulin decreased with As2O3 concentration. Immunocytochemistry revealed changes in the cellular microtubule network and formation of polymerized microtubules in As2O3-treated cells. Conclusion The microtubules alterations found with As2O3 treatment suggest that As2O3 increases the depolymerized forms of tubulin in cells and that this is potentially due to arsenites negative effects on spindle dynamics.

Abstract 2435: Assessment of vascular disrupting properties of sodium meta-arsenite treatment using Dynamic contrast-enhanced MRI in colon cancer allograft model

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL PURPOSE: Sodium meta-arsenite is an orally bioavailable arsenic compound that currently undergoing clinical evaluation. The sodium meta-arsenite leads to blood vessel congestion, the selective destruction of the vasculature, and extensive necrosis in experimental tumors. The aim of this study is to assess the ability of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) to measure the antivascular effects of sodium meta-arsenite in colon cancer allograft model. MATERIALS AND METHODS: Mice CT26 colon cell carcinoma allografts were treated with sodium meta-arsenite or saline. Changes in tumor vascularity were assessed by DCE-MRI. DCE-MRI data were analyzed calculating the k(ep). For histologic analysis, liver, spleen and tumor tissues were taken at 8, 24 and 48 hours after sodium meta-arsenite injection from CT26 tumor allograft models. RESULTS: DCE-MRI results showed comparison between pre-treatment and 24 hr post-treatment Gd-DTPA contrast enhancement T1-weighted MR image. Enhancement has been significantly decreased in sodium meta-arsenite treated group than sham injection group. We also showed extensive central necrosis of tumor by 24 h after treated with sodium meta-arsenite (10 mg/kg, i.p.). CONCLUSION: These results suggest that DCE-MRI could quantitatively visualized the perfusion efficacy of the sodium meta-arsenite acting as a VDA in colon caner allograft model Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2435. doi:1538-7445.AM2012-2435

Abstract 2595: KML001 displays vascular-disrupting properties and irinotecan-combined antitumor activities against a murine tumor model

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Purpose: KML001 (sodium metaarsenite) is an orally available arsenic compound that has entered phase II clinical trials in solid tumors. The aim of this study is to assess vascular-disrupting properties of KML001 and to investigate whether KML001 as VDA (vascular-disrupting agent) augments anti-tumor effects of irinotecan in a murine model of colon cancer. Experimental Design: Female BALBc mice bearing subcutaneos CT26 colon carcinoma cells were injected intraperitoneally with KML001(10 mg/kg) or irinotecan alone, or coadministered weekly for 4 weeks. Moreover, we assessed cytoskeletal changes of HUVEC cells when treated with KML001. Results: We observed massive necrosis in the central part of the tumor by 24 h after treated with KML001 alone and the regrowth was seen from the periphery of the tumor after 2 days. Otherwise, we observed the significant tumor growth delay when KML001 was administered either 24 hr or 72hr after irinotecan. In addition, we found that KML001 degraded tubulin in HUVEC cells, which might be related with vascular disrupting properties of KML001. Evidence of proteosome-mediated degradation was obtained by demonstrating that adding a proteosome inhibitor. Conclusions: These results suggest that KML001 is a novel VDA, which can increase anti-tumor activities of irinotecan. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2595. doi:10.1158/1538-7445.AM2011-2595