Hyunggee Kim

Korea University, Sŏul, Seoul, South Korea

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Publications (83)381.31 Total impact

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    ABSTRACT: Glioblastoma multiforme (GBM) is one of the most aggressive and fatal primary brain tumors in humans. The standard therapy for the treatment of GBM is surgical resection, followed by radiotherapy and/or chemotherapy. However, the frequency of tumor recurrence in GBM patients is very high, and the survival rate remains poor. Delineating the mechanisms of GBM recurrence is essential for therapeutic advances. Here, we demonstrate that irradiation rendered 17-20 % of GBM cells dead, but resulted in 60-80 % of GBM cells growth-arrested with increases in senescence markers, such as senescence-associated beta-galactosidase-positive cells, H3K9me3-positive cells, and p53-p21(CIP1)-positive cells. Moreover, irradiation induced expression of senescence-associated secretory phenotype (SASP) mRNAs and NFκB transcriptional activity in GBM cells. Strikingly, compared to injection of non-irradiated GBM cells into immune-deficient mice, the co-injection of irradiated and non-irradiated GBM cells resulted in faster growth of tumors with the histological features of human GBM. Taken together, our findings suggest that the increases in senescent cells and SASP in GBM cells after irradiation is likely one of main reasons for tumor recurrence in post-radiotherapy GBM patients.
    No preview · Article · Nov 2015 · Tumor Biology
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    ABSTRACT: High-grade gliomas are considered the most malignant of brain tumors and have a poor prognosis. In a previous study, we showed that LIM domain only 2 (LMO2) regulates glioma stem cell properties and tumor angiogenesis and gave rise to highly invasive glioma xenografts. Glioma invasion in the surrounding parenchymal tissues is a major hurdle with respect to eliminating glioma by surgery. Invasive glioma cells are considered one of the main culprits for the recurrence of tumors after therapies. In the current study, we focused on determining the molecular mechanism(s) by which LMO2 regulates glioma cell migration and invasion. Forced expression of LMO2 in human U87MG glioma cells led to glioma invasion, as determined by in vivo xenograft assays and enhanced in vitro migration and invasion. LMO2 was associated with increased levels of cytosolic p27(Kip1) protein. LMO2 possibly induced the stabilization and augmented interactions between p27(Kip1) and RhoA. We knocked down the expression of p27(Kip1), which led to a decrease in LMO2-driven glioma cell migration and invasion. Taken together, our findings indicate that LMO2 promotes glioma cell migration and invasion by increasing the levels of cytosolic p27(Kip1).
    No preview · Article · Sep 2015 · Tumor Biology

  • No preview · Article · Aug 2015 · Cancer Research
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    ABSTRACT: Upregulation of microRNA-21 (miR-21) is known to be strongly associated with the proliferation, invasion, and radio-resistance of glioma cells. However, the regulatory mechanism that governs the biogenesis of miR-21 in glioma is still unclear. Here, we demonstrate that the DEAD-box RNA helicase, DDX23, promotes miR-21 biogenesis at the post-transcriptional level. The expression of DDX23 was enhanced in glioma tissues compared to normal brain, and expression level of DDX23 was highly associated with poor survival of glioma patients. Specific knockdown of DDX23 expression suppressed glioma cell proliferation and invasion in vitro and in vivo, which is similar to the function of miR-21. We found that DDX23 increased the level of miR-21 by promoting primary-to-precursor processing of miR-21 through an interaction with the Drosha microprocessor. Mutagenesis experiments critically demonstrated that the helicase activity of DDX23 was essential for the processing (cropping) of miR-21, and we further found that ivermectin, a RNA helicase inhibitor, decreased miR-21 levels by potentially inhibiting DDX23 activity and blocked invasion and cell proliferation. Moreover, treatment of ivermectin decreased glioma growth in mouse xenografts. Taken together, these results suggest that DDX23 plays an essential role in glioma progression, and might thus be a potential novel target for the therapeutic treatment of glioma. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    No preview · Article · Jun 2015 · Brain
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    ABSTRACT: Epidermal growth factor receptor variant III (EGFRvIII) has been associated with glioma stemness, but the direct molecular mechanism linking the two is largely unknown. Here, we show that EGFRvIII induces the expression and secretion of pigment epithelium-derived factor (PEDF) via activation of signal transducer and activator of transcription 3 (STAT3), thereby promoting self-renewal and tumor progression of glioma stem cells (GSCs). Mechanistically, PEDF sustained GSC self-renewal by Notch1 cleavage, and the generated intracellular domain of Notch1 (NICD) induced the expression of Sox2 through interaction with its promoter region. Furthermore, a subpopulation with high levels of PEDF was capable of infiltration along corpus callosum. Inhibition of PEDF diminished GSC self-renewal and increased survival of orthotopic tumor-bearing mice. Together, these data indicate the novel role of PEDF as a key regulator of GSC and suggest clinical implications.
    Full-text · Article · May 2015 · PLoS Biology
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    ABSTRACT: Interferon regulatory factor 7 (IRF7) is the master transcription factor that plays a pivotal role in the transcriptional activation of type I interferon genes in the inflammatory response. Our previous study revealed that IRF7 is an important regulator of tumor progression via the expression of inflammatory cytokines in glioma. Here, we report that IRF7 promotes glioma invasion and confers resistance to both chemotherapy and radiotherapy by inhibiting expression of argonaute 2 (AGO2), a regulator of microRNA biogenesis. We found that IRF7 and AGO2 expression levels were negatively correlated in patients with glioblastoma multiforme. Ectopic IRF7 expression led to a reduction in AGO2 expression, while depletion of IRF7 resulted in increased AGO2 expression in the LN-229 glioma cell line. In an in vitro invasion assay, IRF7 overexpression enhanced glioma cell invasion. Furthermore, reconstitution of AGO2 expression in IRF7-overexpressing cells led to decreased cell invasion, whereas the reduced invasion due to IRF7 depletion was rescued by AGO2 depletion. In addition, IRF7 induced chemoresistance and radioresistance of glioma cells by diminishing AGO2 expression. Finally, AGO2 depletion alone was sufficient to accelerate glioma cell invasion in vitro and in vivo, indicating that AGO2 regulates cancer cell invasion. Taken together, our results indicate that IRF7 promotes glioma cell invasion and both chemoresistance and radioresistance through AGO2 inhibition.
    No preview · Article · Feb 2015 · Tumor Biology
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    ABSTRACT: Unlabelled: Tumor metastasis involves circulating and tumor-initiating capacities of metastatic cancer cells. Epithelial-mesenchymal transition (EMT) is related to self-renewal capacity and circulating tumor cell (CTC) characteristics for tumor metastasis. Although tumor metastasis is a life-threatening, complicated process that occurs through circulation of tumor cells, mechanistic aspects of self-renewal and circulating capacities have been largely unknown. Hepatic transmembrane 4 L six family member 5 (TM4SF5) promotes EMT for malignant growth and migration, so it was rationalized that TM4SF5, as a hepatocellular carcinoma (HCC) biomarker, might be important for metastatic potential. Here, self-renewal capacity by TM4SF5 was mechanistically explored using hepatocarcinoma cells with or without TM4SF5 expression, and we explored whether they became CTCs using mouse liver-orthotopic model systems. We found that TM4SF5-dependent sphere growth correlated with CD24(-) , aldehyde dehydrogenase (ALDH) activity, as well as a physical association between CD44 and TM4SF5. Interaction between TM4SF5 and CD44 was through their extracellular domains with N-glycosylation modifications. TM4SF5/CD44 interaction activated proto-oncogene tyrosine-protein kinase Src (c-Src)/signal transducer and activator of transcription 3 (STAT3)/Twist-related protein 1 (Twist1)/B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) signaling for spheroid formation, whereas disturbing the interaction, expression, or activity of any component in this signaling pathway inhibited spheroid formation. In serial xenografts using 200∼5,000 cells per injection, TM4SF5-positive tumors exhibited subpopulations with locally increased CD44 expressions, supporting for tumor cell differentiation. TM4SF5-positive, but not TM4SF5- or CD44-knocked-down, cells were identified circulating in blood 4-6 weeks after orthotopic liver injection using in vivo laser scanning endomicroscopy. Anti-TM4SF5 reagent blocked their metastasis to distal intestinal organs. Conclusion: TM4SF5 promotes self-renewal and CTC properties supported by TM4SF5(+) /CD44(+(TM4SF5-bound)) /ALDH(+) /CD24(-) markers during HCC metastasis.
    Full-text · Article · Jan 2015 · Hepatology
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    ABSTRACT: Glioblastoma is a highly aggressive primary brain tumor in which the majority of cancer cells are undifferentiated. One of the most common oncogenic drivers for this malignancy is the epidermal growth factor receptor variant III (EGFRvIII), which lacks a portion of the extracellular ligand-binding domain due to deletion of exons 2–7 of the EGFR gene. EGFRvIII plays a critical role in tumor progression, promoting acquisition of stem cell-like features including an undifferentiated state and therapy resistance. However, the molecular mechanisms by which EGFRvIII contributes to cancer cell aggressiveness remain poorly understood. Here, we show that EGFR expression correlates with JAGGED1 expression in glioblastoma patients. Overexpression of EGFRvIII in glioma cell lines augmented JAGGED1 expression at the transcriptional level through the mitogen-activated protein kinase signaling pathway. Consequently, EGFRvIII overexpression drove partial dedifferentiation of glioma cells, as determined by tumorsphere-forming ability and expression of stem cell markers, through JAGGED1 induction. EGFRvIII-mediated radioresistance, but not chemoresistance, was also modulated by JAGGED1. Taken together, our results provide new insight into the mechanism underlying EGFRvIII-driven glioblastoma aggressiveness.
    No preview · Article · Dec 2014 · Tumor Biology
  • Jun-Kyum Kim · Hee-Young Jeon · Hyunggee Kim
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    ABSTRACT: Chemo-resistance and radio-resistance are a major cause of recurrence and progression of many cancers, regardless of improvements in therapies. Since cancer stem cells (CSCs) were identified as a rare population with the abilities of self-renewal; tumor initiation; aberrant differentiation, which contributes to tumor heterogeneity; and resistance to anticancer therapeutics, they have been considered a major cause of tumor recurrence post-therapy and a primary therapeutic target in relapse prevention. A number of studies have demonstrated the mechanisms underlying chemo-resistance and radio-resistance of CSCs. In this review, we describe intrinsic and extrinsic factors underlying CSC chemo-resistance and radio-resistance. The intrinsic factors regulate CSC signaling pathways involved in stem cell signaling, anti-apoptotic pathways, ABC transporter expression, and DNA damage repair systems. The extrinsic factors include the resistance mechanisms resulting from the interactions between CSCs and the microenvironment composed of vessels, fibroblasts, immune cells, extracellular matrix, and diverse soluble factors. Furthermore, we introduce diverse therapeutic agents used in experimental or clinical trials to target CSCs. Understanding how CSCs acquire resistance to anticancer therapeutics will give us opportunity to develop improved therapeutic approaches.
    No preview · Article · Dec 2014 · Archives of Pharmacal Research
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    ABSTRACT: Abstract In this study, we found that the total polyphenol and ascorbic acid levels in the fruit of Opuntia humifusa are higher than those in other parts of the plant. We further hypothesized that antioxidants in O. humifusa might affect the growth or survival of cancer cells. Hexane extracts of seeds and ethyl acetate extracts of fruits and stems significantly suppressed the proliferation of HeLa cervical carcinoma cells, but did not affect the proliferation of normal human BJ fibroblasts. Additionally, the extracts of O. humifusa induced G1 phase arrest in HeLa cells. The O. humifusa extracts reduced the levels of G1 phase-associated cyclin D1, cyclin-dependent kinase 4 (Cdk4), and phosphorylated retinoblastoma proteins. Moreover, p21(WAF1/Cip1) and p53 expression significantly increased after treatment. We examined the effects of ethyl acetate extracts of O. humifusa fruit (OHF) on HeLa cells xenograft tumor growth. OHF treatment significantly reduced tumor volume and this decrease was correlated with decreased Cdk4 and cyclin D1 expression. Furthermore, flavonoids, trans Taxifolin, and dihydrokaempferol, were isolated from OHF. Thus, this extract may be a promising candidate for treating human cervical carcinoma.
    No preview · Article · Nov 2014 · Journal of Medicinal Food
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    ABSTRACT: The invasiveness of glioblastoma is a major cause of poor prognosis and relapse. However, the molecular mechanism controlling glioma cell invasion is poorly understood. Here, we report that receptor activator of nuclear factor kappa-B (NFκB) ligand (RANKL) promotes glioma cell invasion in vivo, but not in vitro. Unlike the invasiveness under in vitro culture conditions, in vivo xenograft studies revealed that LN229 cells expressing high endogenous RANKL generated more invasive tumors than U87MG cells expressing relatively low endogenous RANKL. Consistently, RANKL-overexpressing U87MG resulted in invasive tumors, whereas RANKL-depleted LN229 generated rarely invasive tumors. We found that the number of activated astrocytes was markedly increased in the periphery of RANKL-high invasive tumors. RANKL activated astrocytes through NFκB signaling and these astrocytes in turn secreted various factors which regulate glioma cell invasion. Among them, transforming growth factor β (TGF-β) signaling was markedly increased in glioblastoma specimens and xenograft tumors expressing high levels of RANKL. These results indicate that RANKL contributes to glioma invasion by modulating the peripheral microenvironment of the tumor, and that targeting RANKL signaling has important implications for the prevention of highly invasive glioblastoma.
    Full-text · Article · Jul 2014 · Cancer Letters
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    ABSTRACT: The Rab protein family is composed of small GTP-binding proteins involved in intracellular vesicle trafficking. In particular, Rab3a which is one of four Rab3 proteins (a, b, c, and d isoforms) is associated with synaptic vesicle trafficking in normal brain. However, despite the elevated level of Rab3a in tumors, its role remains unclear. Here we report a tumorigenic role of Rab3a in brain tumors. Elevated level of Rab3a expression in human was confirmed in both glioma cell lines and glioblastoma multiforme patient specimens. Ectopic Rab3a expression in glioma cell lines and primary astrocytes promoted cell proliferation by increasing cyclin D1 expression, induced resistance to anti-cancer drug and irradiation, and accelerated foci formation in soft agar and tumor formation in nude mice. The overexpression of Rab3a augmented the tumorsphere-forming ability of glioma cells and p53(-/-) astrocytes and increased expression levels of various stem cell markers. Taken together, our results indicate that Rab3a is a novel oncogene involved in glioma initiation and progression.
    Full-text · Article · Jun 2014 · Molecular Biology Reports
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    ABSTRACT: Glioma initiating cells (GICs), which reside within the perivascular microenvironment to maintain self-renewal capacity, are responsible for glioblastoma initiation, progression, and recurrence. However, the molecular mechanisms controlling crosstalk between GICs and endothelial cells are poorly understood. Here we report that, in both GICs and endothelial cells, platelet derived growth factor (PDGF)-driven activation of nitric oxide (NO) synthase increases NO-dependent inhibitor of differentiation 4 (ID4) expression, which in turn promotes JAGGED1-NOTCH activity through suppression of miR-129 that specifically represses JAGGED1suppression. This signaling axis promotes tumor progression along with increased GIC self-renewal and growth of tumor vasculature in the xenograft tumors, which is dramatically suppressed by NOTCH inhibitor. ID4 levels correlate positively with NOS2, HES1, and HEY1 and negatively with miR-129 in primary GICs. Thus, targeting the PDGF-NOS-ID4-miR-129 axis and NOTCH activity in the perivascular microenvironment might serve as an efficacious therapeutic modality for glioblastoma.
    Full-text · Article · Jun 2014 · Cancer Research
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    Se-Yeong Oh · Hyunggee Kim
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    ABSTRACT: Despite current advances in multimodality therapies, such as surgery, radiotherapy, and chemotherapy, the outcome for patients with high-grade glioma remains fatal. Understanding how glioma cells resist various therapies may provide opportunities for developing new therapies. Accumulating evidence suggests that the main obstacle for successfully treating high-grade glioma is the existence of brain tumor stem cells (BTSCs), which share a number of cellular properties with adult stem cells, such as self-renewal and multipotent differentiation capabilities. Owing to their resistance to standard therapy coupled with their infiltrative nature, BTSCs are a primary cause of tumor recurrence post-therapy. Therefore, BTSCs are thought to be the main glioma cells representing a novel therapeutic target and should be eliminated to obtain successful treatment outcomes.
    Preview · Article · Apr 2013
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    Xiong Jin · Xun Jin · Ji-Eun Jung · Samuel Beck · Hyunggee Kim
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    ABSTRACT: Cancer stem cells (CSCs) are the most aggressive cell type in many malignancies. Cell surface proteins are generally used to isolate and characterize CSCs. Therefore, the identification of CSC-specific cell surface markers is very important for the diagnosis and treatment of malignancies. We found that Nestin (a type VI intermediate filament protein), like the glioma stem cell (GSC) markers CD133 and CD15, exhibited different levels of expression in primary human glioblastoma specimens. Similar to our previous finding that cytoplasmic Nestin is expressed as a cell surface form in mouse GSCs, the cell surface form of Nestin was also expressed at different levels in human GSCs. We isolated cell surface Nestin-positive cell populations from human GSCs by fluorescence-activated cell sorting FACS analysis, and observed that these populations exhibited robust CSC properties, such as increased tumorsphere-forming ability and tumorsphere size. Mechanistically, we found that DAPT, a γ-secretase (a multi-subunit protease complex) inhibitor, reduced the proportion of cell surface Nestin-positive cells in human GSCs in a time- and dose-dependent manner, without significant changes in total Nestin expression, implying that a post-translational modification was involved in the generation of cell surface Nestin. Taken together, our data provides the first evidence that cell surface Nestin may serve as a promising GSC marker for the isolation and characterization of heterogeneous GSCs in glioblastomas.
    Full-text · Article · Mar 2013 · Biochemical and Biophysical Research Communications
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    ABSTRACT: Differing sensitivity of influenza A viruses to antiviral effects of the Myxovirus resistance (Mx) protein implies varying global gene expression profiles in the host. The role of Mx protein during lethal avian influenza (AI) virus infection was examined using Mx1-deficient C57BL/6 (B6-Mx1(-/-)) and congenic Mx1-expressing (B6-Mx1(+/+)) mice infected with a virulent, mouse-adapted avian H5N2 Ab/Korea/ma81/07 (Av/ma81) virus. After infection, B6-Mx1(+/+) mice were completely protected from lethal AI-induced mortality, and exhibited attenuated clinical disease and reduced viral titers and pathology in the lungs, compared with B6-Mx1(-/-) mice. Transcriptional profiling of lung tissues revealed that most of the genes up-regulated after infection are involved in activation of the immune response and host defense. Notably, more abundant and sustained expression of cytokine/chemokine genes was observed up to 3 dpi in B6-Mx1(-/-) mice, and this was associated with excessive induction of cytokines and chemokines. Consequently, massive infiltration of macrophages/monocytes and granulocytes into lung resulted in severe viral pneumonia and potentially contributed to decreased survival of B6-Mx1(-/-) mice. Taken together, our data show that dysregulated gene transcriptional activity corresponded to persistent induction of cytokine/chemokines and recruitment of cytokine-producing cells that promote inflammation in B6-Mx1(-/-) mouse lungs. Thus, we provide additional evidence of the interplay of genetic, molecular, and cellular correlates governed by the Mx1 protein that critically determine disease outcome during lethal AI virus infection.
    Full-text · Article · Feb 2013 · American Journal Of Pathology
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    Full-text · Article · Feb 2013 · Virology
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    ABSTRACT: Aberrant epidermal growth factor receptor (EGFR) signaling is a typical oncogenic signature in glioblastoma. Here, we show that EGFR inhibition in primary glioma stem cells (GSCs) with oncogenic EGFRvIII and EGFRvIII-transduced glioma stem-like cells promotes invasion by decreasing ID3 levels. ID3 suppresses GSC invasiveness by inhibiting p27KIP1-RhoA-dependent migration and MMP3 expression. Xenograft and human glioblastoma specimens show that ID3 localizes within glioblastoma cores, whereas p27KIP1 and MMP3 are predominantly expressed in glioma cells in invasive fronts. Together, our findings show that EGFR inhibition induces GSC invasiveness by abolishing ID3-mediated inhibition of p27KIP1 and MMP3 expression.
    Full-text · Article · Jan 2013 · Cancer letters
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    ABSTRACT: CD44 is generally accepted as a surrogate marker for head and neck squamous carcinoma cancer stem cells (HNSC CSCs) and only CD44+ HNSC cells have tumour initiating capacity. However, a recent report suggested that CSCs themselves might be heterogenous due to various genetic alterations. Here, we compared in vitro stem-like cell characteristics, chemoresistance and in vivo tumour formation capacity of CD44+ and CD44- HNSC cells obtained from primary HNSC patient specimens. CD44- HNSC spheroid cells generated spheroid cells again after seeding of single-dissociated spheroid CD44- HNSC cells. Immunocytochemistry assays revealed that various stem cell markers, including octamer-binding transcription factor 4 (OCT4), sex determining region Y-box 2 (SOX2) and nestin were up-regulated in CD44- spheroid cells, similar to CD44+ spheroid cells. Furthermore, CD44- spheroid cells appeared to be chemoresistant to cisplatin and showed increased levels of ABCG2, similar to CD44+ spheroid cells. Of most interest, as few as 1000 CD44- spheroid cells were able to give rise to tumours in nude mice. The collective data indicate that the cell surface marker CD44 cannot be used as a selective marker of spheroid-forming, tumour-initiating or chemoresistant cell populations, and further indicate the limitation of current HNSC CSC identification methods using the CD44 cell surface marker.
    No preview · Article · Jul 2012 · European journal of cancer (Oxford, England: 1990)
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    ABSTRACT: We synthesized fluorescent capsid nanoparticles (FCNPs) by genetically inserting fluorescent protein (FP) (DsRed or eGFP) into each of 240 surface spike tips of hepatitis B virus (HBV) capsid particles. That is, when expressed in E. coli, FCNPs formed spherical nanoparticles with uniform diameter of about 40 nm owing to the self-assembly function of HBV core protein (i.e. basic assembly unit of capsid) and were successfully purified through Ni(+2) affinity- and sucrose gradient based purification. We also added the glycine-rich fexible linker peptides in between DsRed (or eGFP) and capsid to reduce fluorescence quenching among the densely displayed DsReds (or eGFPs) on the capsid surface. As compared to cognate fluorescent monomer proteins, it is notable that FCNPs showed a significantly amplified (160-170-fold) fluorescence intensity and enhanced conformational stability even in 50% serum solutin at 37 °C. The high conformational stability of FCNPs seems to result both from the highly stable structure of HBV capsid particles and from the well oriented insertion of fluorescent protein into capsid spike tip to keep native conformation of DsRed or eGFP. When estimated with continuous exposure to strong excitation light, FCNPs also showed much higher photostability than DsRed, eGFP, and a commonly used organic fluorescent dye, which happened presumably because the enhanced conformational stability of FCNPs significantly reduced photobleaching of fluorophores. Especially, it is notable that rFCNPs stably emitted high-level fluorescence inside mouse for a prolonged period, thereby showing high in vivo stability. The developed FCNPs are likely to have a great potential to be used as an effective and non-cytotoxic tool for in vivo optical imaging as well as in vitro fluorescent reporter in various biomolecular detection assays.
    No preview · Article · Jun 2012 · Biomaterials

Publication Stats

2k Citations
381.31 Total Impact Points

Institutions

  • 2004-2015
    • Korea University
      • • Department of Food Bioscience and Technology
      • • Department of Biotechnology
      Sŏul, Seoul, South Korea
  • 2014
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2009-2011
    • St. Jude Children's Research Hospital
      • Department of Infectious Diseases
      Memphis, Tennessee, United States
  • 2007
    • Dana-Farber Cancer Institute
      • Department of Medical Oncology
      Boston, Massachusetts, United States
    • Chungbuk National University
      Chinsen, Chungcheongbuk-do, South Korea
  • 2003
    • Harvard Medical School
      Boston, Massachusetts, United States
  • 2000-2002
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
  • 2001
    • Seoul National University
      • Department of Agricultural Biotechnology
      Sŏul, Seoul, South Korea