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Jai-Hee Moon,
Wonjin Yun,
Jihyun Kim,
Solji Hyeon,
Phil Jun Kang,
Gyuman Park,
Aeree Kim,
Sejong Oh,
Kwang Youn Whang,
Dong-Wook Kim,
Byung Sun Yoon, Seungkwon You
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ABSTRACT: Oct4-Sox2-Nanog transcriptional networks are critical for the maintenance of embryonic stem (ES) cell self-renewal and induction of pluripotency. However, in transcription factor-induced reprogramming of somatic cells into induced pluripotent stem cells (iPSCs), Nanog is initially dispensable and Oct4 remains the sole factor that could not be substituted/ommitted. Here, we show that mouse fibroblasts could be reprogrammed into iPSCs by Nanog and Bmi1, which replaces Sox2, Klf4, and c-Myc, in the absence of Oct4. Furthermore, we show that in the presence of shh agonists (oxysterol and purmophamine), which replaces the function of Bmi1, a single transcription factor, Nanog is sufficient to reprogram mouse fibroblasts into iPSCs. Nanog-induced iPSCs resemble mESCs in terms of morphology, global gene expression profiles, epigenetic status and pluripotency both in vitro and in vivo. These findings support that Nanog can replace the Oct4 for the somatic cell reprogramming and underlie the mechanisms of Nanog in reprogramming process.
Biochemical and Biophysical Research Communications 01/2013; · 2.48 Impact Factor
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Bona Kim,
Byung Sun Yoon,
Jai Hee Moon,
Jonggun Kim,
Eun Kyoung Jun,
Jung Han Lee,
Jun Sung Kim,
Cheong Soon Baik,
Aeree Kim,
Kwang Youn Whang, Seungkwon You
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ABSTRACT: Recent evidence has suggested that human skin fibroblasts may represent a novel source of therapeutic stem cells. In this study, we report a 3-stage method to induce the differentiation of skin fibroblasts into insulin- producing cells (IPCs). In stage 1, we establish the isolation, expansion and characterization of mesenchymal stem cells from human labia minora dermis- derived fibroblasts (hLMDFs) (stage 1: MSC expansion). hLMDFs express the typical mesenchymal stem cell marker proteins and can differentiate into adipocytes, osteoblasts, chondrocytes or muscle cells. In stage 2, DMEM/F12 serum-free medium with ITS mix (insulin, transferrin, and selenite) is used to induce differentiation of hLMDFs into endoderm-like cells, as determined by the expression of the endoderm markers Sox17, Foxa2, and PDX1 (stage 2: mesenchymal-endoderm transition). In stage 3, cells in the mesenchymal- endoderm transition stage are treated with nicotinamide in order to further differentiate into self-assembled, 3-dimensional islet cell-like clusters that express multiple genes related to pancreatic β-cell development and function (stage 3: IPC). We also found that the transplantation of IPCs can normalize blood glucose levels and rescue glucose homeostasis in streptozotocin- induced diabetic mice. These results indicate that hLMDFs have the capacity to differentiate into functionally competent IPCs and represent a potential cell-based treatment for diabetes mellitus.
Experimental and Molecular Medicine 01/2012; 44(1):26-35. · 2.48 Impact Factor
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Jai-Hee Moon,
June Seok Heo,
Suhyun Kwon,
Jihyun Kim,
Jihye Hwang,
Phil Jun Kang,
Aeree Kim,
Hyun Ok Kim,
Kwang Youn Whang,
Byung Sun Yoon, Seungkwon You
Journal of Molecular Cell Biology 11/2011; 4(1):59-62.
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ABSTRACT: Self-renewal, differentiation, and tumorigenicity characterize cancer stem cells (CSCs), which are rare and maintained by specific cell fate regulators. CSCs are isolated from glioblastoma multiforme (GBM) and may be responsible for the lethality of incurable brain tumors. Brain CSCs may arise from the transformation of undifferentiated, nestin-positive neural stem or progenitor cells and GFAP-expressing astrocytes. Here, we report a role of Nanog in the genesis of cancer stem-like cells. Using primary murine p53-knockout astrocytes (p53(-/-) astrocytes), we provide evidence that enforced Nanog expression can increase the cellular growth rate and transform phenotypes in vitro and in vivo. In addition, Nanog drives p53(-/-) astrocytes toward a dedifferentiated, CSC-like phenotype with characteristic neural stem cell/progenitor marker expression, neurosphere formation, self-renewal activity, and tumor development. These findings suggest that Nanog promotes dedifferentiation of p53-deficient mouse astrocytes into cancer stem-like cells by changing the cell fate and transforming cell properties.
Biochemical and Biophysical Research Communications 08/2011; 412(1):175-81. · 2.48 Impact Factor
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Jai-Hee Moon,
June Seok Heo,
Jun Sung Kim,
Eun Kyoung Jun,
Jung Han Lee,
Aeree Kim,
Jonggun Kim,
Kwang Youn Whang,
Yong-Kook Kang,
Seungeun Yeo,
Hee-Joung Lim,
Dong Wook Han,
Dong-Wook Kim,
Sejong Oh,
Byung Sun Yoon,
Hans R Schöler, Seungkwon You
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ABSTRACT: Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by the transcription factors Oct4, Sox2, and Klf4 in combination with c-Myc. Recently, Sox2 plus Oct4 was shown to reprogram fibroblasts and Oct4 alone was able to reprogram mouse and human neural stem cells (NSCs) into iPS cells. Here, we report that Bmi1 leads to the transdifferentiation of mouse fibroblasts into NSC-like cells, and, in combination with Oct4, can replace Sox2, Klf4 and c-Myc during the reprogramming of fibroblasts into iPS cells. Furthermore, activation of sonic hedgehog signaling (by Shh, purmorphamine, or oxysterol) compensates for the effects of Bmi1, and, in combination with Oct4, reprograms mouse embryonic and adult fibroblasts into iPS cells. One- and two-factor iPS cells are similar to mouse embryonic stem cells in their global gene expression profile, epigenetic status, and in vitro and in vivo differentiation into all three germ layers, as well as teratoma formation and germline transmission in vivo. These data support that converting fibroblasts with Bmi1 or activation of the sonic hedgehog pathway to an intermediate cell type that expresses Sox2, Klf4, and N-Myc allows iPS generation via the addition of Oct4.
Cell Research 06/2011; 21(9):1305-15. · 8.19 Impact Factor
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Jinlong Yin,
Jun-Kyum Kim,
Jai-Hee Moon,
Samuel Beck,
Dachuan Piao,
Xun Jin,
Sung-Hak Kim,
Young Chang Lim,
Do-Hyun Nam, Seungkwon You,
Hyunggee Kim,
Yun-Jaie Choi
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ABSTRACT: Glioma stem cells (GSCs) are known to be maintained within a "vascular niche"; thereby, disruption of this microenvironment using antiangiogenesis agents is a promising therapeutic modality. However, this regimen leads to treatment failure and tumor recurrence in patients with glioblastoma multiforme (GBM). Therefore, more effective therapeutic approaches that can eradicate GSCs and the bulk tumors are needed. Toward this goal, we examined the antitumor effects of an antiangiogenesis approach combined with conventional chemotherapy on suppressing glioma xenograft growth. We established three genetically engineered mesenchymal stem cell (MSC) lines (GE-AF-MSCs) by stably transducing the gene encoding endostatin (an antiangiogenesis factor), the gene encoding secretable form of carboxylesterase 2 (sCE2, a prodrug-activating enzyme), or a mixture of both genes. Among the three GE-AF-MSC cell lines, injection of amniotic fluid (AF)-MSCs-endostatin-sCE2 cells into U87MG-EGFRvIII-driven orthotopic brain tumor and postsurgery tumor recurrence models, and subsequent CPT11 treatment yielded the strongest antitumor responses, including diminished angiogenesis, increased cell death, and a reduced Nestin-positive GSC population. Therefore, our antitumor strategy provides a novel basis for designing stem cell-mediated therapeutic approaches to target and eradicate GSCs and the bulk tumors.
Molecular Therapy 03/2011; 19(6):1161-9. · 6.87 Impact Factor
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Byung Sun Yoon,
Eun Kyoung Jun,
Gyuman Park,
Seung Jun Yoo,
Jai-Hee Moon,
Cheong Soon Baik,
Aeree Kim,
Hyunggee Kim,
Jong-Hoon Kim,
Gou Young Koh,
Hoon Taek Lee, Seungkwon You
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ABSTRACT: The self-renewal of embryonic stem cells involves a balance between processes governed by crosstalk between intrinsic and extrinsic factors. We hypothesized that protein serine/threonine phosphatase 2A (PP2A) may play a central role in the signaling pathways that regulate human embryonic stem cell (hESC) self-renewal. Biochemical analyses revealed that PP2A activity gradually increases over the course of hESC differentiation; PP2A/C and PP2A/A levels also increased. The overexpression of PP2A/C or the addition of PP2A activator C2-ceramide promoted hESC differentiation. Accordingly, the addition of PP2A inactivator okadaic acid (OA) maintained hESC self-renewal in the absence of basic fibroblast growth factor (bFGF). The hESCs maintained with OA expressed pluripotency markers and exhibited substantial telomerase activity with normal karyotypes. The hESCs were able to differentiate into derivatives of the three germ layers, both in vitro and in vivo. Furthermore, the addition of OA and bFGF enabled the maintenance of hESC self-renewal without feeder cells, even in chemically defined xeno-free media. These findings shed a light on the role of PP2A in hESC differentiation and provide a novel strategy for maintaining the self-renewal capability of hESC in bFGF-free, feeder cell-free, and xeno-free media through the optimal suppression of PP2A activity using OA.
Stem Cells 03/2010; 28(5):874-84. · 7.78 Impact Factor
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Byung Sun Yoon,
Jai-Hee Moon,
Eun Kyoung Jun,
Jonggun Kim,
Isaac Maeng,
Jun Sung Kim,
Jung Han Lee,
Cheong Soon Baik,
Aeree Kim,
Kyoung Shik Cho,
Jang Ho Lee,
Hwang Heui Lee,
Kwang Youn Whang, Seungkwon You
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ABSTRACT: Recent evidence shows that amniotic fluid (AF) contains multiple cell types derived from the developing fetus, and may represent a novel source of stem cells for cell therapy. In this study, we examined the paracrine factors released by human amniotic fluid-derived mesenchymal stem cells (AF-MSCs) and their ability to accelerate the wound-healing process by stimulating proliferation and migration of dermal fibroblasts. AF-MSCs expressed the typical MSC marker proteins CD13, CD29, and CD44 and differentiated into adipocytes, osteoblasts, and chondrocytes when exposed to the appropriate differentiation media. In addition, AF-MSC-conditioned media (AF-MSC-CM) significantly enhanced proliferation of dermal fibroblasts. Antibody-based protein array and enzyme-linked immunosorbent assay (ELISA) indicated that AF-MSC-CM contains various cytokines and chemokines that are known to be important in normal wound healing, including IL-8, IL-6, TGF-beta, TNFRI, VEGF, and EGF. Application of AF-MSC-CM significantly enhanced wound healing by dermal fibroblasts via the TGF-beta/SMAD2 pathway. Levels of p-SMAD2 were increased by AF-MSC-CM, and both the increase in p-SMAD2 and migration of dermal fibroblasts were blocked by inhibiting the TGF-beta/SMAD2 pathway. Moreover, in a mouse excisional wound model, AF-MSC-CM accelerated wound healing. These data provide the first evidence of the potential for AF-MSC-CM in the treatment of skin wounds.
Stem cells and development 09/2009; 19(6):887-902. · 4.15 Impact Factor
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ABSTRACT: Chemotherapy agents have adverse immunotherapeutic effects secondary to inhibition of hematopoietic stem cell proliferation, particularly in committed lymphoblast. Certain anti-cancer drugs have immuno-modulatory properties, although mechanisms are still not fully understood. In the current study, we explored the effects of doxorubicin on peripheral blood CD4(+) and CD8(+) T-cell responses pre- and post-stimulation. Doxorubicin treatment alone had no effects on peripheral blood T lymphocytes and regulatory T-cells in vivo and in vitro. However, CD4(+) T-cells were resistant to doxorubicin and demonstrated more robust proliferation than CD8(+) T-cells after doxorubicin pre-treatment. CD40 ligand and 4-1BB expression on the surface of CD4(+) T-cells were increased after TCR-ligation activation; however, expression on CD8(+) T-cells was not increased. Dendritic cells cultured in the presence of activated CD4(+) T-cells pre-treated with doxorubicin had greater survival rates than those cultured with activated CD8(+) T-cells. Doxorubicin pre-treatment followed by anti-CD3epsilon+anti-4-1BB activation led to proliferation of CD4(+) T-cells and no proliferative effects on CD8(+) T-cells. Our results collectively suggest that doxorubicin pre-treatment in cancer patients may be a more effective way to enhance anti-cancer immune responses by increased antigen-specific CD4(+) Th1 immune responses.
International immunopharmacology 09/2009; 9(13-14):1530-9. · 2.21 Impact Factor
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Jai-Hee Moon,
Sung Sik Kwak,
Gyuman Park,
Hye-Youn Jung,
Byung Sun Yoon,
Jaeyeo Park,
Kyung Su Ryu,
Seung-Cheol Choi,
Isaac Maeng,
Bona Kim,
Eun Kyung Jun,
Soonseong Kim,
Aeree Kim,
Sejong Oh,
Hyunggee Kim,
Ki Dong Kim, Seungkwon You
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ABSTRACT: In this study, we report the isolation and characterization of a population of multipotent keloid-derived mesenchymal-like stem cells (KMLSCs) from keloid scalp tissues. These KMLSCs expressed the typical mesenchymal stem cell marker proteins CD13, CD29, CD44, CD90, fibronectin, and vimentin when they were cultured in serum-containing medium and when subsequent exposure to various differentiation media resulted in their differentiation into adipocytes, osteoblasts, chondrocytes, smooth muscle cells, and angiogenic endothelial cells. When KMLSCs were cultured in neural stem culture conditions (i.e., in the presence of epidermal growth factor and fibroblast growth factor 2 in substrate-free conditions), they produced large numbers of neurospheres containing nestin-, CD133-, and SOX2-positive cells that expressed neural-crest stem cell markers. Subsequent exposure of these cells to different differentiation conditions resulted in cells that expressed neuronal cell-, astrocyte-, oligodendrocyte-, or Schwann cell-specific markers. Our study suggests that KMLSCs may be an alternative adult stem cell resource for regenerative tissue repair and auto-transplantation.
Stem cells and development 09/2008; 17(4):713-24. · 4.15 Impact Factor
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Jai-Hee Moon,
Byung Sun Yoon,
Bona Kim,
Gyuman Park,
Hye-Youn Jung,
Isaac Maeng,
Eun Kyoung Jun,
Seung Jun Yoo,
Aeree Kim,
Sejong Oh,
Kwang Youn Whang,
Hyunggee Kim,
Dong-Wook Kim,
Ki Dong Kim, Seungkwon You
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ABSTRACT: Recently, Bmi1 was shown to control the proliferation and self-renewal of neural stem cells (NSCs). In this study, we demonstrated the induction of NSC-like cells (NSCLCs) from mouse astrocytes by Bmi1 under NSC culture conditions. These NSCLCs exhibited the morphology and growth properties of NSCs, and expressed NSC marker genes, including nestin, CD133, and Sox2. In vitro differentiation of NSCLCs resulted in differentiated cell populations containing astrocytes, neurons, and oligodendrocytes. Following treatment with histone deacetylase inhibitors (trichostatin A and valproic acid), the potential of NSCLCs for proliferation, dedifferentiation, and self-renewal was significantly inhibited. Our data indicate that multipotent NSCLCs can be generated directly from astrocytes by the addition of Bmi1.
Biochemical and Biophysical Research Communications 07/2008; · 2.48 Impact Factor
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Gyuman Park,
Byung Sun Yoon,
Jai-Hee Moon,
Bona Kim,
Eun Kyoung Jun,
Sejong Oh,
Hyunggee Kim,
Hea Joon Song,
Joo Young Noh,
Chilhwan Oh, Seungkwon You
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ABSTRACT: Keloids are benign skin tumors characterized by collagen accumulation and hyperproliferation of fibroblasts. To find an effective therapy for keloids, we explored the pharmacological potential of (-)-epigallocatechin-3-gallate (EGCG), a widely investigated tumor-preventive agent. When applied to normal and keloid fibroblasts (KFs) in vitro, proliferation and migration of KFs were more strongly suppressed by EGCG than normal fibroblast proliferation and migration (IC(50): 54.4 microM (keloid fibroblast (KF)) versus 63.0 microM (NF)). The level of Smad2/3, signal transducer and activator of transcription-3 (STAT3), and p38 phosphorylation is more enhanced in KFs, and EGCG inhibited phosphorylation of phosphatidylinositol-3-kinase (PI3K), extracellular signal-regulated protein kinase 1/2 (ERK1/2), and STAT3 (Tyr705 and Ser727). To evaluate the contribution of these pathways to keloid pathology, we treated KFs with specific inhibitors for PI3K, ERK1/2, or STAT3. Although a PI3K inhibitor significantly suppressed proliferation, PI3K and MEK/ERK inhibitors had a minor effect on migration and collagen production. However, a JAK2/STAT3 inhibitor and a STAT3 siRNA strongly suppressed proliferation, migration, and collagen production by KFs. We also found that treatment with EGCG suppressed growth and collagen production in the in vivo keloid model. This study demonstrates that EGCG suppresses the pathological characteristics of keloids through inhibition of the STAT3-signaling pathway. We propose that EGCG has potential in the treatment and prevention of keloids.
Journal of Investigative Dermatology 06/2008; 128(10):2429-41. · 6.31 Impact Factor
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Joong-Seob Lee,
Jung-Eun Gil,
Jong-Hoon Kim,
Tae-Kyung Kim,
Xun Jin,
Se-Yeong Oh,
Young-Woo Sohn,
Hye-Min Jeon,
Hyo-Jung Park,
Jong-Whi Park,
Yong-Jae Shin,
Yong Gu Chung,
Jang-Bo Lee, Seungkwon You,
Hyunggee Kim
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ABSTRACT: Here, we show that H-ras(V12) causes the p53-knockout mouse astrocytes (p53-/- astrocytes) to be transformed into brain cancer stem-like cells. H-ras(V12) triggers the p53-/- astrocytes to express a Nestin and a Cd133, which are expressed in normal and cancer neural stem cells. H-ras(V12) also induces the formation of a single cell-derived neurosphere under neural stem cell culture conditions. Furthermore, H-ras(V12)-overexpressing p53-/- astrocytes (p53-/-ast-H-ras(V12)) possess an in vitro self-renewal capacity, and are aberrantly differentiated into Tuj1-positve neurons both in vitro and in vivo. Amongst a variety of Ras-mediated canonical signaling pathways, we demonstrated that the MEK/ERK signaling pathway is responsible for neurosphere formation in p53-deficient astrocytes, whereas the PI3K/AKT signaling pathway is involved in oncogenic transformation in these cells. These findings suggest that the activation of Ras signaling pathways promotes the generation of brain cancer stem-like cells from p53-deficient mouse astrocytes by changing cell fate and transforming cell properties.
Biochemical and Biophysical Research Communications 02/2008; 365(3):496-502. · 2.48 Impact Factor
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Yoonjung Kho,
Sungchan Kim,
Byung Sun Yoon,
Jai-Hee Moon,
Bona Kim,
Sungwook Kwak,
Junghee Woo,
Sejong Oh,
Kichang Hong,
Saehun Kim,
Hyunggee Kim, Seungkwon You,
Yunjaie Choi
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ABSTRACT: In this study, we examined the expression and functions of serum amyloid A (SAA) isoforms during apoptosis of HC11 mammary gland epithelial cells. Expression of SAA mRNAs and apoptosis were increased in HC11 cells by serum withdrawal and gradually decreased upon the addition of serum, or epidermal growth factor (EGF). TNFalpha treatment of HC11 cells also induced expression of SAA genes, and the effect on SAA1 and SAA2 expression was suppressed by treatment with MG132, and in cells transfected with a dominant negative mutant form of IkappaBalpha. Similar results were observed in response to interleukin-1 (IL-1), IL-6 and interferon gamma (IFNgamma). Furthermore, overexpression of the SAA1 and SAA2 isoforms suppressed growth and accelerated apoptosis of HC11 cells by increasing caspase 3/7 and caspase 8 activities, but the apoptotic effect of tumor necrosis factor alpha (TNFalpha) on HC11 cells was not enhanced. We found that expression of SAA1 and SAA2, but not SAA3, was regulated by an NFkappaB-dependent pathway, and that overexpression of SAA isoforms accelerated the apoptosis of HC11 cells.
Bioscience Biotechnology and Biochemistry 02/2008; 72(1):70-81. · 1.28 Impact Factor
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Yoonjung Kho,
Sungchan Kim,
Byung Sun Yoon,
Jai-Hee Moon,
Sungwook Kwak,
Gyuman Park,
Junghee Woo,
Sejong Oh,
Kichang Hong,
Saehun Kim,
Hyunggee Kim, Seungkwon You,
Yunjaie Choi
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ABSTRACT: In this study, we show that expression of the Westmead DMBA8 nonmetastatic cDNA 1 (WDNM1) gene was increased upon SFM and/or TNFalpha treatment, with a corresponding increase in apoptotic cells, and gradually decreased following re-stimulation with serum in HC11 mammary epithelial cells. TNFalpha induced WDNM1 expression showed the NFkappaB-dependent mechanism since it's expression was abrogated in IkappaBalphaM (super-repressor of NFkappaB)-transfected cells, but not those transfected with control vector. Furthermore, overexpression of WDNM1 suppressed growth and differentiation, and accelerated apoptosis of HC11 cells. Thus, our results demonstrate that WDNM1 gene expression, regulated by the TNFalpha-NFkappaB signal pathway, is associated with HC11 cell apoptosis.
Animal Biotechnology 02/2008; 19(2):89-103. · 0.93 Impact Factor
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Tae-Kyung Kim,
Joong-Seob Lee,
Se-Yeong Oh,
Xun Jin,
Yun-Jaie Choi,
Tae-Hoon Lee,
Eun ho Lee,
Young-Ki Choi, Seungkwon You,
Yong Gu Chung,
Jang-Bo Lee,
Ronald A DePinho,
Lynda Chin,
Hyunggee Kim
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ABSTRACT: IFN regulatory factor 3 (IRF3) is a transcriptional factor that plays a crucial role in activation of innate immunity and inflammation in response to viral infection, and is also involved in p53-dependent inhibition of cell growth. Although functional activation of IRF3 by viral infection is relatively well documented, the biological role and regulatory mechanism underlying cell growth inhibition by IRF3 are poorly understood. Here, we show a novel regulatory pathway connecting IRF3-promyelocytic leukemia protein (PML)-p53 in primary and cancer cell lines. Overexpression of IRF3 induces p53-dependent cell growth inhibition in cancer cell lines with normal p53 activity. In addition, doxycycline-induced expression of IRF3 in U87MG cells inhibits tumor growth in nude mice in vivo. IRF3 is found to increase expression of PML by a direct transcriptional activation as determined by PML-promoter-luciferase and chromatin immunoprecipitation assays. When PML is depleted by RNA interference-mediated knockdown, IRF3 fails to increase p53 acetylation and its transcriptional activity. Taken together, the results of the present study indicate that direct transcriptional activation of PML by IRF3 results in the p53-dependent growth inhibition of normal and cancer cells in vitro and in vivo, which is suggestive of a novel regulatory network between the innate immune response and tumor suppression.
Cancer Research 01/2008; 67(23):11133-40. · 7.86 Impact Factor
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Se-Yeong Oh,
Young-Woo Sohn,
Jong-Whi Park,
Hyo-Jung Park,
Hye-Min Jeon,
Tae-Kyung Kim,
Joong-Seob Lee,
Ji-Eun Jung,
Xun Jin,
Yong Gu Chung,
Young-Ki Choi, Seungkwon You,
Jang-Bo Lee,
Hyunggee Kim
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ABSTRACT: We have established several glioma-relevant oncogene-engineered cancer cells to reevaluate the oncogene-selective cytotoxicity of previously well-characterized anticancer drugs, such as etoposide, doxorubicin, staurosporine, and carmustine. Among several glioma-relevant oncogenes (activated epidermal growth factor receptor, Ras, and Akt, as well as Bcl-2 and p53DD used in the present study), the activated epidermal growth factor receptor, Ras, and Akt exerted oncogenic transformation of Ink4a/Arf(-/-) murine astrocyte cells. We identified that etoposide, a topoisomerase II inhibitor, caused selective killing of myristylated Akt (Akt-myr)-transduced Ink4a/Arf(-/-) astrocytes and U87MG cells in a dose- and time-dependent manner. Etoposide-selective cytotoxicity in the Akt-myr-transduced cells was shown to be caused by nonapoptotic cell death and occurred in a p53-independent manner. Etoposide caused severe reactive oxygen species (ROS) accumulation preferentially in the Akt-myr-transduced cells, and elevated ROS rendered these cells highly sensitive to cell death. The etoposide-selective cell death of Akt-myr-transduced cells was attenuated by pepstatin A, a lysosomal protease inhibitor. In the present study, we show that etoposide might possess a novel therapeutic activity for oncogenic Akt-transduced cancer cells to kill preferentially through ROS-mediated damage.
Molecular Cancer Therapeutics 09/2007; 6(8):2178-87. · 5.23 Impact Factor
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Tae-Kyung Kim,
Joong-Seob Lee,
Ji-Eun Jung,
Se-Yeong Oh,
Sungwook Kwak,
Xun Jin,
Soo-Yeon Lee,
Jang-Bo Lee,
Yong Gu Chung,
Young Ki Choi, Seungkwon You,
Hyunggee Kim
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ABSTRACT: Interferon regulatory factor 3 (IRF3) is a transcriptional factor that plays a crucial role in activation of innate immunity and inflammation in response to viral infection. We investigated the biological function of IRF3 overexpressed in somatic cells such as fibroblasts and astrocytes. Similar to overexpression of oncogenic H-ras in the normal human fibroblast, overexpression of IRF3 in human fibroblast BJ cells was shown to decrease cell growth and increase senescence-associated beta-galactosidase activity by activating a p53 tumor suppressor. BCNU, a DNA damage agent, further accelerated p53 function and cell death in the IRF3-overexpressed BJ cells compared to control BJ cells, without increased expression of IRF3 target genes. IRF3 failed to activate p53 function and cell growth inhibition in BJ cells downregulating p53 by RNAi-mediated p53 knockdown. Furthermore, enforced expression of IRF3 did not show any effect of cell growth inhibition in astrocytes or embryonic fibroblasts derived from the p53(-/-) mouse. When compared to control BJ cells, BJ cells which downregulated IRF3 by RNAi-mediated IRF3 knockdown showed extended in vitro life span. Taken together, the present study indicates that IRF3 should be a novel inducer of cell growth inhibition and cellular senescence through activation of p53 tumor suppressor.
Cancer Letters 11/2006; 242(2):215-21. · 4.24 Impact Factor
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Xun Jin,
Joong-Seub Lee,
Sungwook Kwak,
Ji-Eun Jung,
Tae-Kyung Kim,
Chenxiong Xu,
Zhongshan Hong,
Zhehu Li,
Sun-Myoung Kim,
Kwang Youn Whang,
Ki-Chang Hong, Seungkwon You,
Yun-Jaie Choi,
Hyunggee Kim
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ABSTRACT: We have established in culture a spontaneously immortalized bovine embryonic fibroblast (BEF) cell line that has lost p53 and p16(INK4a) functions. MyoD is a muscle-specific regulator capable of inducing myogenesis in a number of cell types. When the BEF cells were transduced with MyoD they differentiated efficiently to desmin-positive myofibers in the presence of 2% horse serum and 1.7 nM insulin. The myogenic differentiation of this cell line was more rapid and obvious than that of C2C12 cells, as judged by morphological changes and expression of various muscle regulatory factors. To confirm that lack of the p53 and p16(INK4a) pathway does not prevent MyoD-mediated myogenesis, we established a cell line transformed with SV40LT (BEFV) and introduced MyoD into it. In the presence of 2% horse serum and 1.7 nM insulin, the MyoD-transduced BEFV cells differentiated like the MyoD-transduced BEFS cells, and displayed a similar pattern of expression of muscle regulatory proteins. Taken together, our results indicate that MyoD overexpression overcomes the defect in muscle differentiation associated with immortalization and cell transformation caused by the loss of p53 and Rb functions.
Molecules and Cells 05/2006; 21(2):206-12. · 2.18 Impact Factor
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ABSTRACT: Cell replacement therapy is a promising approach for the treatment of cardiac diseases. It is, however, challenged by a limited supply of appropriate cells. Therefore, we have investigated whether functional cardiomyocytes can be efficiently generated from human embryonic stem cells (hESCs). In this study, we developed an efficient protocol for the generation of functional cardiomyocytes from hESCs by combining hanging drop culture and 5-azacytidine, a well-known demethylating agent, and then evaluated the expression of cardiac-specific markers. hESCs were cultured both in the medium without or with 0.1, 1, or 10 microM of 5-azacytidine under a hanging drop culture. The expression of several cardiac-specific markers was determined by real-time PCR, RT-PCR, immunofluorescence, and confocal microscopy. To verify the structural and functional properties of hESC-derived cardiomyocytes, we performed electron microscopy and electrophysiological recording. The efficiency of beating cell generation was significantly improved in the hanging drop culture compared with that in suspension culture. Treatment of hESCs with 0.1 microM of 5-azacytidine for 1-3 days significantly increased the number of beating cells and simultaneously enhanced the expression of cardiac-specific markers. Transmission electron microscopy and electrophysiological recording showed that hESC-derived cardiomyocytes acquired structural and functional properties of cardiomyocytes. In conclusion, these results suggest that differentiation of hESCs into cardiomyocytes can be enhanced by the combination of hanging drop culture and 5-azacytidine treatment. Also the methylation status of genes related to cardiomyocyte development may play an important role in the differentiation of hESCs into cardiomyocytes.
Differentiation 05/2006; 74(4):149-59. · 2.81 Impact Factor
