Yeon Mi Ryu

Near-Infrared Fluorescence Imaging Using a Protease-Specific Probe for the Detection of Colon Tumors

BACKGROUND/AIMS Early tumor detection is crucial for the prevention of colon cancer. Near-infrared fluorescence (NIRF) imaging using a target-activatable probe may permit earlier disease detection. Matrix metalloproteinases (MMPs) participate in tumorigenesis and tumor growth. The aim of this study was to determine whether NIRF imaging using an MMP-activatable probe can detect colon tumors at early stages. METHODS WE UTILIZED TWO MURINE COLON CANCER MODELS: a sporadic colon cancer model induced by azoxymethane (AOM), and a colitis-associated cancer model induced by a combination of AOM and dextran sodium sulfate (DSS). Colonic lesions were analyzed by histologic examination, Western blotting, immunohistochemical staining, and NIRF imaging using an MMP-activatable probe. RESULTS Multiple variable-sized tumors developed in both models and progressed from adenomas to adenocarcinomas over time. At the early stage of the AOM/DSS model, diffuse inflammation was observed within the tumors. MMP expression increased progressively through normal, inflammation, adenoma, and adenocarcionoma stages. NIRF signal intensities were strongly correlated with each tumor stage from adenoma to adenocarcinoma. NIRF imaging also distinguished tumors from inflamed mucosa. CONCLUSIONS NIRF imaging using a protease-activatable probe may be a useful tool for early tumor detection. This approach could translate to improve the endoscopic detection of colon tumors, especially in patients with inflammatory bowel disease.

15-Hydroxyprostaglandin Dehydrogenase is Downregulated and Exhibits Tumor Suppressor Activity in Gastric Cancer

We investigated the tumor suppressor activity and regulatory mechanism of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in gastric cancer; 15-PGDH expression was lost in 70.1% of malignant human gastric tissues, but was preserved in normal and metaplastic gastritis. KATO III and SNU-719 cells were transfected with pcDNA3.1-empty vector or an expression vector encoding wild-type 15-PGDH. In TUNEL assays apoptotic cell numbers were increased in KATO-PGDH-WT cells compared with control. We found that EGFR and ERK1/2 inhibitors clearly increased the expression of 15-PGDH in KATO III cells. Our findings demonstrate both downregulation and a tumor suppressor activity of 15-PGDH in gastric cancer.

Cancer-Microenvironment-Sensitive Activatable Quantum Dot Probe in the Second Near-Infrared Window

Recent technological advances have expanded fluorescence (FL) imaging into the second near-infrared region (NIR-II; wavelength = 1000-1700 nm), providing high spatial resolution through deep tissues. However, bright and compact fluorophores are rare in this region, and sophisticated control over NIR-II probes has not been fully achieved yet. Herein, we report an enzyme-activatable NIR-II probe that exhibits FL upon matrix metalloprotease activity in tumor microenvironment. Bright and stable PbS/CdS/ZnS core/shell/shell quantum dots (QDs) were synthesized as a model NIR-II fluorophore, and activatable modulators were attached to exploit photoexcited electron transfer (PET) quenching. The quasi type-II QD band alignment allowed rapid and effective FL modulations with the compact surface ligand modulator that contains methylene blue PET quencher. The modulator was optimized to afford full enzyme accessibility and high activation signal surge upon the enzyme activity. Using a colon cancer mouse model, the probe demonstrated selective FL activation at tumor sites with 3-fold signal enhancement in 10 min. Optical phantom experiments confirmed the advantages of the NIR-II probe over conventional dyes in the first near-infrared region.

Endoscopic Transplantation of Mesenchymal Stem Cell Sheets in Experimental Colitis in Rats

Owing to the recent progress in regenerative medicine technology, clinical trials that harnessed the regeneration and immune modulation potentiality of stem cells for treating IBD have shown promising results. We investigated the feasibility and utility of intraluminal endoscopic transplantation of rat MSC sheets in murine models of experimental colitis for targeted delivery of stem cells to lesions. We isolated adipose-derived mesenchymal stem cells (AD-MSC) and bone marrow-derived mesenchymal stem cells (BM-MSC) from EGFP-transgenic rats and fabricated the cells in sheet forms using temperature-responsive culture dishes. The MSC sheets were endoscopically transplanted to the inflamed area in electrocoagulation and DNBS colitis model. The effect of the transplantation was verified using endoscopic scoring and histological analysis. In the electrocoagulation model, the AD-MSC group showed significantly decreased ulcer size in the transplanted regions. In the DNBS colitis model, the AD-MSC group showed decreased inflammation and colitis in the transplanted regions. Histologic analysis showed that the MSC sheets had successfully attached to the inflamed mucosa in both the electrocoagulation and DNBS colitis model. Our results show that endoscopic transplantation of MSC sheets could be a new effective mode of stem cell therapy for IBD treatment.

Abstract 5378: Inhibition of 15-hydroxyprostaglandin dehydrogenase by Helicobacter pylori in human gastric carcinogenesis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Helicobacter pylori (H pylori) infection induces a chronic inflammatory response, which promotes gastric carcinogenesis. 15-hydroxyprostaglandin dehydrogenase (15-PGDH) plays a key role as a tumor suppressor in gastrointestinal cancers. The aim of this study was to elucidate the role of 15-PGDH in gastric carcinogenesis associated with H pylori. 15-PGDH expression in gastric biopsies from H pylori-infected (n=25) and non-infected (n=15) subjects was analyzed by quantitative real-time PCR, western blot analysis, and immunohistochemisty. 15-PGDH DNA methylation was evaluated by methylation specific PCR and pyrosequencing. The expression of 15-PGDH, Snail, ERK1/2, TLR4 and MyD88 in response to H pylori infection was assessed by immunoblot analysis. Compared to negative specimens, H pylori positive specimens had 2-fold lower 15-PGDH mRNA levels and significantly less 15-PGDH protein. In four H pylori infected subjects with longitudinal follow-up, the suppression of 15-PGDH expression was reversed by H pylori eradication therapy. In parallel with suppressing 15-PGDH expression, H pylori infection activated expression of TLR4 and MyD88 expression, increased levels of phospho-ERK1/2, and increased expression of Snail. Inhibition of MyD88 reversed suppression of 15-PGDH expression and reduced phosphorylated ERK1/2. Similarly, treatment with an ERK1/2 inhibitor also restored 15-PGDH expression. Heliocobacter pylori appeared to promote gastric carcinogenesis by suppressing15-PGDH. This process is mediated by the TLR4/MyD88 pathway via ERK1/2 and Snail transcriptional regulation. 15-PGDH may be a useful marker and a potential therapeutic target in H pylori-induced gastric carcinogenesis. Citation Format: Yeon Mi Ryu, Seung-Jae Myung, Young Soo Park3, Ho June Song, Dong-Hoon Yang, Jin-Yong Jeong, Sun Mi Lee, Miyeoun Song, Do Hoon Kim, Hyo-Jeong Lee, Stephen P. Fink, Sandy D. Markowitz, Kee Wook Jung, Kyung-Jo Kim, Byong Duk Ye, Jung-Sik Byeon, Hwoon-Yong Jung, Suk-Kyun Yang, Jin-Ho Kim. Inhibition of 15-hydroxyprostaglandin dehydrogenase by Helicobacter pylori in human gastric carcinogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5378. doi:10.1158/1538-7445.AM2013-5378