Sang-Yeob Kim

Spraying Quantum Dot Conjugates in the Colon of Live Animals Enabled Rapid and Multiplex Cancer Diagnosis Using Endoscopy

The detection of colon cancer using endoscopy is widely used, but the interpretation of the diagnosis is based on the clinicians naked eye. This is subjective and can lead to false detection. Here we developed a rapid and accurate molecular fluorescence imaging technique using antibody-coated quantum dots (Ab-QDs) sprayed and washed simultaneously on colon tumor tissues inside live animals, subsequently excited and imaged by endoscopy. QDs were conjugated to matrix metalloproteinases (MMP) 9, MMP 14, or carcinoembryonic antigen (CEA) Abs with zwitterionic surface coating to reduce nonspecific bindings. The Ab-QD probes can diagnose tumors on sectioned mouse tissues, fresh mouse colons stained ex vivo and also in vivo as well as fresh human colon adenoma tissues in 30 min and can be imaged with a depth of 100 μm. The probes successfully detected not only cancers that are readily discernible by bare eyes but also hyperplasia and adenoma regions. Sum and cross signal operations provided postprocessed images that can show complementary information or regions of high priority. This multiplexed quantum dot, spray-and-wash, and endoscopy approach provides a significant advantage for detecting small or flat tumors that may be missed by conventional endoscopic examinations and bestows a strategy for the improvement of cancer diagnosis.

Histone Deacetylase 3 and 4 Complex Stimulates the Transcriptional Activity of the Mineralocorticoid Receptor.

Histone deacetylases (HDACs) act as corepressors in gene transcription by altering the acetylation of histones, resulting in epigenetic gene silencing. We previously reported that HDAC3 acts as a coactivator of the mineralocorticoid receptor (MR). Although HDAC3 forms complexes with class II HDACs, their potential role in the transcriptional activity of MR is unclear. We hypothesized that HDAC4 of the class II family stimulates the transcriptional activity of MR. The expression of MR target genes was measured by quantitative real-time PCR. MR and RNA polymerase II recruitment to promoters of MR target genes was analyzed by chromatin immunoprecipitation. The association of MR with HDACs was investigated by co-immunoprecipitation. MR acetylation was determined with an anti-acetyl-lysine antibody after immunoprecipitation with an anti-MR antibody. Among the class II HDACs, HDAC4 interacted with both MR and HDAC3 after aldosterone stimulation. The nuclear translocation of HDAC4 was mediated by protein kinase A (PKA) and protein phosphatases (PP). The transcriptional activity of MR was significantly decreased by inhibitors of PKA (H89), PP1/2 (calyculin A), class I HDACs (MS-275), but not class II HDACs (MC1568). MR acetylation was increased by H89, calyculin A, and MS-275, but not by MC1568. Interaction between MR and HDAC3 was significantly decreased by H89, calyculin A, and HDAC4 siRNA. A non-genomic effect of MR via PKA and PP1/2 induced nuclear translocation of HDAC4 to facilitate the interaction between MR and HDAC3. Thus, we have uncovered a crucial role for a class II HDAC in the activation of MR-dependent transcription.

Intravital imaging of mouse colonic adenoma using MMP-based molecular probes with multi-channel fluorescence endoscopy

Intravital imaging has provided molecular, cellular and anatomical insight into the study of tumor. Early detection and treatment of gastrointestinal (GI) diseases can be enhanced with specific molecular markers and endoscopic imaging modalities. We present a wide-field multi-channel fluorescence endoscope to screen GI tract for colon cancer using multiple molecular probes targeting matrix metalloproteinases (MMP) conjugated with quantum dots (QD) in AOM/DSS mouse model. MMP9 and MMP14 antibody (Ab)-QD conjugates demonstrate specific binding to colonic adenoma. The average target-to-background (T/B) ratios are 2.10 ± 0.28 and 1.78 ± 0.18 for MMP14 Ab-QD and MMP9 Ab-QD, respectively. The overlap between the two molecular probes is 67.7 ± 8.4%. The presence of false negative indicates that even more number of targeting could increase the sensitivity of overall detection given heterogeneous molecular expression in tumors. Our approach indicates potential for the screening of small or flat lesions that are precancerous.

Schisandrin B suppresses TGFβ1-induced stress fiber formation by inhibiting myosin light chain phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCEnSchisandra chinensis fruit extract (SCE) has been used as a traditional oriental medicine for treating vascular diseases. However, the pharmacologic effects and mechanisms of SCE on vascular fibrosis are still largely unknown. Transforming growth factor β1 (TGFβ1)-mediated cellular changes are closely associated with the pathogenesis of vascular fibrotic diseases. Particularly, TGFβ1 induces actin stress fiber formation that is a crucial mechanism underlying vascular smooth muscle cell (VSMC) migration in response to vascular injury. In this study, we investigated the effect of SCE and its active ingredients on TGFβ1-induced stress fiber assembly in A7r5 VSMCs.nnnMATERIALS AND METHODSnTo investigate pharmacological actions of SCE and its ingredients on TGFβ1-treated VSMCs, we have employed molecular and cell biological technologies, such as confocal microscopy, fluorescence resonance energy transfer, western blotting, and radiometric enzyme analyses.nnnRESULTSnWe found that SCE inhibited TGFβ1-induced stress fiber formation and cell migration. Schisandrin B (SchB) showed the most prominent effect among the active ingredients of SCE tested. SchB reduced TGFβ1-mediated phosphorylation of myosin light chain, and this effect was independent of RhoA/Rho-associated kinase pathway. Fluorescence resonance energy transfer and radiometric enzyme assays confirmed that SchB inhibited myosin light chain kinase activity. We also showed that SchB decreased TGFβ1-mediated induction of α-smooth muscle actin by inhibiting Smad signaling.nnnCONCLUSIONSnThe present study demonstrates that SCE and its active ingredient SchB suppressed TGFβ1-induced stress fiber formation at the molecular level. Therefore, our findings may help future investigations to develop multi-targeted therapeutic strategies that attenuate VSMC migration and vascular fibrosis.

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.

Suppression of colitis-associated carcinogenesis through modulation of IL-6/STAT3 pathway by balsalazide and VSL#3.

Recent studies suggest that the anti‐inflammatory agent balsalazide (BSZ) and probiotic agent VSL#3 have potential therapeutic benefits for the treatment of patients with inflammatory bowel disease. However, their effectiveness in preventing colitis‐associated carcinogenesis (CAC) remains uncertain. The aim of the present study was to determine the chemopreventive effects of BSZ and VSL#3 in the murine azoxymethane (AOM)/dextran sodium sulfate (DSS) model.

Optical molecular imaging for diagnosing intestinal diseases.

Real-time visualization of the molecular signature of cells can be achieved with advanced targeted imaging techniques using molecular probes and fluorescence endoscopy. This molecular optical imaging in gastrointestinal endoscopy is promising for improving the detection of neoplastic lesions, their characterization for patient stratification, and the assessment of their response to molecular targeted therapy and radiotherapy. In inflammatory bowel disease, this method can be used to detect dysplasia in the presence of background inflammation and to visualize inflammatory molecular targets for assessing disease severity and prognosis. Several preclinical and clinical trials have applied this method in endoscopy; however, this field has just started to evolve. Hence, many problems have yet to be solved to enable the clinical application of this novel method.

O-GlcNAcylation of ATG4B positively regulates autophagy by increasing its hydroxylase activity

Autophagy is a catabolic degradation process and maintains cellular homeostasis. And autophagy is activated in response to various stress conditions. Although O-GlcNAcylation functions a sensor for nutrient and stress, the relationship between O-GlcNAcylation and autophagy is largely unknown. Here, we identified that ATG4B is novel target for O-GlcNAcylation under metabolic stress condition. Treatment with PugNAc, an O-GlcNAcase inhibitor increased activation of autophagy in SH-SY5Y cells. Both bimolecular fluorescence complementation and immunoprecipitation assay indicated that OGT directly interacts with ATG4B in SH-SY5Y cells. We also found that the O-GlcNAcylated ATG4B was increased in autophagy activation conditions, and down-regulation of OGT reduces O-GlcNAcylation of ATG4B under low glucose condition. Furthermore, the proteolytic activity of ATG4B for LC3 cleavage was enhanced in PugNAc-treated cells. Taken together, these results imply that O-GlcNAcylation of ATG4B regulates autophagy activation by increasing its proteolytic activity under metabolic stress condition.

Combination of metformin and VSL#3 additively suppresses western-style diet induced colon cancer in mice

&NA; Western‐style diet (WD) and dysbiosis are known to be associated with colonic inflammation, which contributes to carcinogenesis. Metformin (Met) exerts anti‐inflammatory effects to induce AMP‐activated protein kinase (AMPK), resulting in suppressed protein synthesis and reduced cell proliferation. Probiotic VSL#3 (V) modifies microbial composition. We investigated the chemopreventive mechanisms of Met and V in WD‐induced colitis‐associated colon carcinogenesis. Male BALB/c mice were randomly divided into five groups: a control diet (CD) group, WD group, WD+ Met (250 mg/kg/day) group, WD+V (1.3 million bacteria/day) group, and WD+Met+V group. All mice were exposed to azoxymethane (10 mg/kg) followed by 2% dextran sodium sulfate (DSS) for 7 days. Using HCT‐116 human colon cancer cell line, expression of AMPK, extracellular signal‐regulated kinase (ERK), cyclin D1, and Bcl‐2 was investigated and cell cycle arrest was assessed. WD enhanced the severity of colitis and tumor growth compared with CD. The combination of Met and V significantly ameliorated colitis and tumor growth by inhibiting macrophage infiltration and maintaining epithelial integrity. In vitro assays showed that the combination therapy promoted late apoptosis by inhibiting cyclin D1 and Bcl‐2 and activating pro‐apoptotic ERK. A combination therapy with Met and V attenuates tumor growth in a mouse model of WD‐induced colitic cancer, suggesting that this strategy could be useful for the chemoprevention of colon cancer.

Interleukin-4 receptor-targeted delivery of Bcl-xL siRNA sensitizes tumors to chemotherapy and inhibits tumor growth

IL-4 receptor (IL-4R) is commonly up-regulated on tumor cells, and interactions between the receptor and Interleukin-4 (IL-4) can induce the expression of anti-apoptotic proteins, including Bcl-xL. This contributes to tumor cell survival and their resistance to chemotherapy. In this study, we exploited IL-4R-targeted delivery of Bcl-xL siRNA to IL-4R-expressing tumor cells in order to sensitize them to chemotherapy. To target IL-4R, an IL-4R-binding peptide, IL4RPep-1, was attached to branched polyethyleneimine-superparamagnetic iron oxide nanoparticles (BPEI-SPION). These nanoparticles were then complexed with Bcl-xL-targeting siRNA. IL-4R-targeted BPEI-SPION/Bcl-xL siRNA more efficiently reduced Bcl-xL gene expression and enhanced cytotoxicity of doxorubicin in MDA-MB231 breast tumor cells compared to untargeted BPEI-SPION/Bcl-xL siRNA. The siRNA was released from the complexes after 15xa0h of incubation at pH 5.5 and was stable in the complexes up to 72xa0h in the serum. The IL-4R-targeted BPEI-SPION/siRNA was internalized by cells through IL-4R, successfully escaped the endosomes, and was dispersed into the cytoplasm. Near-infrared fluorescence and magnetic resonance imaging demonstrated that inxa0vivo tumor homing and accumulation of IL-4R-targeted BPEI-SPION/siRNA were both higher than untargeted BPEI-SPION/siRNA. The IL-4R-targeted BPEI-SPION/Bcl-xL siRNA, in combination with doxorubicin, significantly inhibited tumor growth in mice compared to untargeted BPEI-SPION/Bcl-xL siRNA. These results suggest that the IL-4R-targeted delivery of Bcl-xL siRNA to IL-4R-expressing tumors can sensitize tumors to chemotherapy and enhance the efficacy of anti-tumor therapeutics.