Publications by authors named "Seong Who Kim"

89 Publications

Optimal Ratio of Wnt3a Expression in Human Mesenchymal Stem Cells Promotes Axonal Regeneration in Spinal Cord Injured Rat Model.

J Korean Neurosurg Soc 2021 Sep 28;64(5):705-715. Epub 2021 May 28.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: Through our previous clinical trials, the demonstrated therapeutic effects of MSC in chronic spinal cord injury (SCI) were found to be not sufficient. Therefore, the need to develop stem cell agent with enhanced efficacy is increased. We transplanted enhanced Wnt3asecreting human mesenchymal stem cells (hMSC) into injured spines at 6 weeks after SCI to improve axonal regeneration in a rat model of chronic SCI. We hypothesized that enhanced Wnt3a protein expression could augment neuro-regeneration after SCI.

Methods: Thirty-six Sprague-Dawley rats were injured using an Infinite Horizon (IH) impactor at the T9-10 vertebrae and separated into five groups : 1) phosphate-buffered saline injection (injury only group, n=7); 2) hMSC transplantation (MSC, n=7); 3) hMSC transfected with pLenti vector (without Wnt3a gene) transplantation (pLenti-MSC, n=7); 4) hMSC transfected with Wnt3a gene transplantation (Wnt3a-MSC, n=7); and 5) hMSC transfected with enhanced Wnt3a gene (1.7 fold Wnt3a mRNA expression) transplantation (1.7 Wnt3a-MSC, n=8). Six weeks after SCI, each 5×105 cells/15 µL at 2 points were injected using stereotactic and microsyringe pump. To evaluate functional recovery from SCI, rats underwent Basso-Beattie-Bresnahan (BBB) locomotor test on the first, second, and third days post-injury and then weekly for 14 weeks. Axonal regeneration was assessed using growth-associated protein 43 (GAP43), microtubule-associated protein 2 (MAP2), and neurofilament (NF) immunostaining.

Results: Fourteen weeks after injury (8 weeks after transplantation), BBB score of the 1.7 Wnt3a-MSC group (15.0±0.28) was significantly higher than that of the injury only (10.0±0.48), MSC (12.57±0.48), pLenti-MSC (12.42±0.48), and Wnt3a-MSC (13.71±0.61) groups (p<0.05). Immunostaining revealed increased expression of axonal regeneration markers GAP43, MAP2, and NF in the Wnt3a-MSC and 1.7 Wnt3a-MSC groups.

Conclusion: Our results showed that enhanced gene expression of Wnt3a in hMSC can potentiate axonal regeneration and improve functional recovery in a rat model of chronic SCI.
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http://dx.doi.org/10.3340/jkns.2021.0003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8435649PMC
September 2021

EPHA3 Contributes to Epigenetic Suppression of PTEN in Radioresistant Head and Neck Cancer.

Biomolecules 2021 04 18;11(4). Epub 2021 Apr 18.

Department of Otolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan 44033, Korea.

EPHA3, a member of the EPH family, is overexpressed in various cancers. We demonstrated previously that EPHA3 is associated with radiation resistance in head and neck cancer via the PTEN/Akt/EMT pathway; the inhibition of EPHA3 significantly enhances the efficacy of radiotherapy in vitro and in vivo. In this study, we investigated the mechanisms of PTEN regulation through EPHA3-related signaling. Increased DNA methyltransferase 1 (DNMT1) and enhancer of zeste homolog 2 (EZH2) levels, along with increased histone H3 lysine 27 trimethylation (H3K27me3) levels, correlated with decreased levels of PTEN in radioresistant head and neck cancer cells. Furthermore, PTEN is regulated in two ways: DNMT1-mediated DNA methylation, and EZH2-mediated histone methylation through EPHA3/C-myc signaling. Our results suggest that EPHA3 could display a novel regulatory mechanism for the epigenetic regulation of PTEN in radioresistant head and neck cancer cells.
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http://dx.doi.org/10.3390/biom11040599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8073943PMC
April 2021

MDM2-dependent Sirt1 degradation is a prerequisite for Sirt6-mediated cell death in head and neck cancers.

Exp Mol Med 2021 Mar 16;53(3):422-431. Epub 2021 Mar 16.

Department of Otolaryngology & Department of Biochemistry and Molecular Biology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.

Sirt6 is involved in multiple biological processes, including aging, metabolism, and tumor suppression. Sirt1, another member of the sirtuin family, functionally overlaps with Sirt6, but its role in tumorigenesis is controversial. In this study, we focused on cell death in association with Sirt6/Sirt1 and reactive oxygen species (ROS) in head and neck squamous cell carcinomas (HNSCCs). Sirt6 induced cell death, as widely reported, but Sirt1 contributed to cell death only when it was suppressed by Sirt6 via regulation of MDM2. Sirt6 and Sirt6-mediated suppression of Sirt1 upregulated ROS, which further led to HNSCC cell death. These results provide insight into the molecular roles of Sirt6 and Sirt1 in tumorigenesis and could therefore contribute to the development of novel strategies to treat HNSCC.
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http://dx.doi.org/10.1038/s12276-021-00578-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8080835PMC
March 2021

Epigenetic regulation of p62/SQSTM1 overcomes the radioresistance of head and neck cancer cells via autophagy-dependent senescence induction.

Cell Death Dis 2021 03 5;12(3):250. Epub 2021 Mar 5.

Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Tumors are composed of subpopulations of cancer cells with functionally distinct features. Intratumoral heterogeneity limits the therapeutic effectiveness of cancer drugs. To address this issue, it is important to understand the regulatory mechanisms driving a subclonal variety within a therapy-resistant tumor. We identified tumor subclones of HN9 head and neck cancer cells showing distinct responses to radiation with different levels of p62 expression. Genetically identical grounds but epigenetic heterogeneity of the p62 promoter regions revealed that radioresistant HN9-R clones displayed low p62 expression via the creation of repressive chromatin architecture, in which cooperation between DNMT1 (DNA methyltransferases 1) and HDAC1 (histone deacetylases 1) resulted in DNA methylation and repressive H3K9me3 and H3K27me3 marks in the p62 promoter. Combined inhibition of DNMT1 and HDAC1 by genetic depletion or inhibitors enhanced the suppressive effects on proliferative capacity and in vivo tumorigenesis following irradiation. Importantly, ectopically p62-overexpressed HN9-R clones increased the induction of senescence along with p62-dependent autophagy activation. These results demonstrate the heterogeneous expression of p62 as the key component of clonal variation within a tumor against irradiation. Understanding the epigenetic diversity of p62 heterogeneity among subclones allows for improved identification of the functional state of subclones and provides a novel treatment option to resolve resistance to current therapies.
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http://dx.doi.org/10.1038/s41419-021-03539-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7935951PMC
March 2021

miR-351-5p/Miro2 axis contributes to hippocampal neural progenitor cell death via unbalanced mitochondrial fission.

Mol Ther Nucleic Acids 2021 Mar 23;23:643-656. Epub 2020 Dec 23.

Department of Microbiology, University of Ulsan College of Medicine, Seoul 05505, Korea.

Adult hippocampal neurogenesis supports the structural and functional plasticity of the brain, while its decline is associated with neurodegeneration common in Alzheimer's disease (AD). Although the dysregulation of certain microRNAs (miRNAs) in AD have been observed, the effects of miRNAs on hippocampal neurogenesis are largely unknown. In this study, we demonstrated miR-351-5p as a causative factor in hippocampal neural progenitor cell death through modulation of the mitochondrial guanosine triphosphatase (GTPase), Miro2. Downregulation of Miro2 by siMiro2 induced cell death, similar to miR-351-5p, whereas ectopic Miro2 expression using an adenovirus abolished these effects. Excessively fragmented mitochondria and dysfunctional mitochondria were indexed by decreased mitochondrial potential, and increased reactive oxygen species were identified in miR-351-5p-induced cell death. Moreover, subsequent induction of mitophagy via Pink1 and Parkin was observed in the presence of miR-351-5p and siMiro2. The suppression of mitochondrial fission by Mdivi-1 completely inhibited cell death by miR-351-5p. miR-351-5p expression increased whereas the level of Miro2 decreased in the hippocampus of AD model mice, emulating expression in AD patients. Collectively, the data indicate the mitochondrial fission and accompanying mitophagy by miR-351-5p/Miro2 axis as critical in hippocampal neural progenitor cell death, and a potential therapeutic target in AD.
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http://dx.doi.org/10.1016/j.omtn.2020.12.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848773PMC
March 2021

p53-dependent glutamine usage determines susceptibility to oxidative stress in radioresistant head and neck cancer cells.

Cell Signal 2021 01 31;77:109820. Epub 2020 Oct 31.

Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address:

The manner in which p53 maintains redox homeostasis and the means by which two key metabolic elements, glucose and glutamine, contribute to p53-dependent redox stability remain unclear. To elucidate the manner in which p53 deals with glucose-deprived, reactive oxygen species (ROS)-prone conditions in this regard, two isogenic cancer subclones (HN3R-A and HN3R-B) bearing distinct p53 mutations as an in vitro model of intratumoral p53 heterogeneity were identified. Following cumulative irradiation, the subclones showed a similar metabolic shift to aerobic glycolysis and increasing NADPH biogenesis for cellular defense against oxidative damage irrespective of p53 status. The radioresistant cancer cells became more sensitive to glycolysis-targeting drugs. However, in glucose-deprived and ROS-prone conditions, HN3R-B, the subclone with the original p53 increased the utilization of glutamine by GLS2, thereby maintaining redox homeostasis and ATP. Conversely, HN3R-A, the p53-deficient radioresistant subclone displayed an impairment in glutamine usage and high susceptibility to metabolic stresses as well as ROS-inducing agents despite the increased ROS scavenging system. Collectively, our findings suggest that p53 governs the alternative utilization of metabolic ingredients, such as glucose and glutamine, in ROS-prone conditions. Thus, p53 status may be an important biomarker for selecting cancer treatment strategies, including metabolic drugs and ROS-inducing agents, for recurrent cancers after radiotherapy.
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http://dx.doi.org/10.1016/j.cellsig.2020.109820DOI Listing
January 2021

Tristetraprolin Posttranscriptionally Downregulates TRAIL Death Receptors.

Cells 2020 08 7;9(8). Epub 2020 Aug 7.

Department of Otorhinolaryngology, GangNeung Asan Hospital, University of Ulsan College of Medicine, Gangneung 25440, Korea.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has attracted attention as a potential candidate for cancer therapy. However, many primary cancers are resistant to TRAIL, even when combined with standard chemotherapy. The mechanism of TRAIL resistance in cancer cells has not been fully elucidated. The TRAIL death receptor (DR) 3'-untranslated region (3'-UTR) is reported to contain AU-rich elements (AREs) that are important for regulating DR mRNA stability. However, the mechanisms by which DR mRNA stability is determined by its 3'-UTR are unknown. We demonstrate that tristetraprolin (TTP), an ARE-binding protein, has a critical function of regulating DR mRNA stability. DR4 mRNA contains three AREs and DR5 mRNA contains four AREs in 3'-UTR. TTP bound to all three AREs in DR4 and ARE3 in DR5 and enhanced decay of DR4/5 mRNA. TTP overexpression in colon cancer cells changed the TRAIL-sensitive cancer cells to TRAIL-resistant cells, and down-regulation of TTP increased TRAIL sensitivity via DR4/5 expression. Therefore, this study provides a molecular mechanism for enhanced levels of TRAIL DRs in cancer cells and a biological basis for posttranscriptional modification of TRAIL DRs. In addition, TTP status might be a biomarker for predicting TRAIL response when a TRAIL-based treatment is used for cancer.
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http://dx.doi.org/10.3390/cells9081851DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7465502PMC
August 2020

Mitophagy deficiency increases NLRP3 to induce brown fat dysfunction in mice.

Autophagy 2021 05 13;17(5):1205-1221. Epub 2020 May 13.

Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Although macroautophagy/autophagy deficiency causes degenerative diseases, the deletion of essential autophagy genes in adipocytes paradoxically reduces body weight. Brown adipose tissue (BAT) plays an important role in body weight regulation and metabolic control. However, the key cellular mechanisms that maintain BAT function remain poorly understood. in this study, we showed that global or brown adipocyte-specific deletion of , a Parkinson disease-related gene involved in selective mitochondrial autophagy (mitophagy), induced BAT dysfunction, and obesity-prone type in mice. Defective mitochondrial function is among the upstream signals that activate the NLRP3 inflammasome. NLRP3 was induced in brown adipocyte precursors (BAPs) from knockout (KO) mice. Unexpectedly, NLRP3 induction did not induce canonical inflammasome activity. Instead, NLRP3 induction led to the differentiation of KO BAPs into white-like adipocytes by increasing the expression of white adipocyte-specific genes and repressing the expression of brown adipocyte-specific genes. deletion in knockout mice reversed BAT dysfunction. Conversely, adipose tissue-specific KO mice showed significantly lower expression of in their BAT. Overall, our data suggest that the role of mitophagy is different from general autophagy in regulating adipose tissue and whole-body energy metabolism. Our results uncovered a new mitochondria-NLRP3 pathway that induces BAT dysfunction. The ability of the knockouts to rescue BAT dysfunction suggests the transcriptional function of NLRP3 as an unexpected, but a quite specific therapeutic target for obesity-related metabolic diseases. ACTB: actin, beta; BAPs: brown adipocyte precursors; BAT: brown adipose tissue; BMDMs: bone marrow-derived macrophages; CASP1: caspase 1; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; ChIP: chromatin immunoprecipitation; EE: energy expenditure; HFD: high-fat diet; IL1B: interleukin 1 beta; ITT: insulin tolerance test; KO: knockout; LPS: lipopolysaccharide; NLRP3: NLR family, pyrin domain containing 3; PINK1: PTEN induced putative kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; RD: regular diet; ROS: reactive oxygen species; RT: room temperature; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type.
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http://dx.doi.org/10.1080/15548627.2020.1753002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143238PMC
May 2021

Branched-chain amino acids sustain pancreatic cancer growth by regulating lipid metabolism.

Exp Mol Med 2019 11 29;51(11):1-11. Epub 2019 Nov 29.

Department of Biomedical Sciences, Asan Medical Center, AMIST, University of Ulsan College of Medicine, Seoul, 05505, South Korea.

Branched-chain amino acid (BCAA) catabolism and high levels of enzymes in the BCAA metabolic pathway have recently been shown to be associated with cancer growth and survival. However, the precise roles of BCAA metabolism in cancer growth and survival remain largely unclear. Here, we found that BCAA metabolism has an important role in human pancreatic ductal adenocarcinoma (PDAC) growth by regulating lipogenesis. Compared with nontransformed human pancreatic ductal (HPDE) cells, PDAC cells exhibited significantly elevated BCAA uptake through solute carrier transporters, which were highly upregulated in pancreatic tumor tissues compared with normal tissues. Branched-chain amino-acid transaminase 2 (BCAT2) knockdown markedly impaired PDAC cell proliferation, but not HPDE cell proliferation, without significant alterations in glutamate or reactive oxygen species levels. Furthermore, PDAC cell proliferation, but not HPDE cell proliferation, was substantially inhibited upon knockdown of branched-chain α-keto acid dehydrogenase a (BCKDHA). Interestingly, BCKDHA knockdown had no significant effect on mitochondrial metabolism; that is, neither the level of tricarboxylic acid cycle intermediates nor the oxygen consumption rate was affected. However, BCKDHA knockdown significantly inhibited fatty-acid synthesis, indicating that PDAC cells may utilize BCAAs as a carbon source for fatty-acid biosynthesis. Overall, our findings show that the BCAA metabolic pathway may provide a novel therapeutic target for pancreatic cancer.
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http://dx.doi.org/10.1038/s12276-019-0350-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6884453PMC
November 2019

The Upregulation of Toll-Like Receptor 3 via Autocrine IFN-β Signaling Drives the Senescence of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Through JAK1.

Front Immunol 2019 23;10:1659. Epub 2019 Jul 23.

Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Although mesenchymal stromal cells (MSCs) are among the most promising cell sources for cell-based therapies and regenerative medicine, the decline in their function with age due to cellular senescence limits their therapeutic applications. Unveiling the underlying mechanism of MSC senescence is therefore of substantial interest with regard to advancing MSC-based cell therapies. We here show that the induction of human umbilical cord blood-derived MSC (UCB-MSC) senescence causes the predominant upregulation of Toll-like receptor 3 (TLR3). Subsequent TLR3 activation by polyinosinic-polycytidylic acid triggers the prominent features of senescence. Using a clustered regularly interspaced short palindromic repeats/Cas9 library screening system, we identified Janus kinase 1 (JAK1) as the candidate regulatory factor for TLR3-mediated MSC senescence. A JAK1 deficiency blocked the MSC senescence phenotype upon TLR3 activation and TLR3 induction. Targeting the JAK1 pathway using chemical JAK1 inhibitors also significantly suppressed TLR3-mediated MSC senescence. Importantly, we further observed that UCB-MSC senescence is driven by a senescence-associated secretory phenotype (SASP) and that interferon-β (IFN-β) is a component of TLR3-dependent SASP, whereby its autocrine actions upregulate TLR3 and suppress cell proliferation. A JAK1 depletion significantly interrupted these effects of IFN-β, indicating that JAK1 is a signaling mediator linking IFN-β activity to TLR3 expression and the process of MSC senescence. Collectively, our findings provide new mechanistic insights into UCB-MSC senescence by revealing the role of an autocrine regulatory loop of SASP evoked by TLR3 activation.
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http://dx.doi.org/10.3389/fimmu.2019.01659DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6665952PMC
November 2020

Elevated Neuropeptide Y in Endothelial Dysfunction Promotes Macrophage Infiltration and Smooth Muscle Foam Cell Formation.

Front Immunol 2019 18;10:1701. Epub 2019 Jul 18.

Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Endothelial dysfunction has been linked to vascular inflammation and foam cell formation but the underlying mechanisms still remain unclear. We sought to define the factors inducing inflammation and smooth muscle foam cell formation under endothelial dysfunction using endothelial nitric oxide synthase (eNOS)-deficient mice. Vascular smooth muscle cells (VSMCs) from eNOS-deficient mice displayed increased expression of macrophage-related genes and elevated lipid uptake. Neuropeptide Y (NPY) was upregulated in the aorta from the eNOS-deficient mice and promoted macrophage chemotaxis toward VSMCs while enhancing the activity of matrix metalloproteinase-3. Notably, NPY induced lipid uptake in VSMCs, facilitating smooth muscle foam cell formation, in association with enhanced expression of genes related to modified low-density lipoprotein uptake and macrophages. NPY was augmented by inflammatory pentraxin 3 (PTX3) in VSMCs. PTX3 enhanced macrophage migratory capacity through the NPY/neuropeptide Y receptor axis and this effect was attenuated by pharmacological inhibition with a receptor-specific antagonist. These observations suggest that endothelial dysfunction leads to the elevation of NPY that amplifies vascular inflammation by increasing inflammatory cell chemotaxis and triggers smooth muscle foam cell formation.
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http://dx.doi.org/10.3389/fimmu.2019.01701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657015PMC
October 2020

Mesenchymal stem cells prevent the progression of diabetic nephropathy by improving mitochondrial function in tubular epithelial cells.

Exp Mol Med 2019 07 9;51(7):1-14. Epub 2019 Jul 9.

Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea.

The administration of mesenchymal stem cells (MSCs) was shown to attenuate overt as well as early diabetic nephropathy in rodents, but the underlying mechanism of this beneficial effect is largely unknown. Inflammation and mitochondrial dysfunction are major pathogenic factors in diabetic nephropathy. In this study, we found that the repeated administration of MSCs prevents albuminuria and injury to tubular epithelial cells (TECs), an important element in the progression of diabetic nephropathy, by improving mitochondrial function. The expression of M1 macrophage markers was significantly increased in diabetic kidneys compared with that in control kidneys. Interestingly, the expression of arginase-1 (Arg1), an important M2 macrophage marker, was reduced in diabetic kidneys and increased by MSC treatment. In cultured TECs, conditioned media from lipopolysaccharide-activated macrophages reduced peroxisomal proliferator-activated receptor gamma coactivator 1α (Pgc1a) expression and impaired mitochondrial function. The coculture of macrophages with MSCs increased and decreased the expression of Arg1 and M1 markers, respectively. Treatment with conditioned media from cocultured macrophages prevented activated macrophage-induced mitochondrial dysfunction in TECs. In the absence of MSC coculture, Arg1 overexpression in macrophages reversed Pgc1a suppression in TECs. These observations suggest that MSCs prevent the progression of diabetic nephropathy by reversing mitochondrial dysfunction in TECs via the induction of Arg1 in macrophages.
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http://dx.doi.org/10.1038/s12276-019-0268-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6802630PMC
July 2019

Progressive Impairment of NK Cell Cytotoxic Degranulation Is Associated With TGF-β1 Deregulation and Disease Progression in Pancreatic Cancer.

Front Immunol 2019 21;10:1354. Epub 2019 Jun 21.

Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Natural killer (NK) cells are key effectors in cancer immunosurveillance and can be used as a prognostic biomarker in diverse cancers. Nonetheless, the role of NK cells in pancreatic cancer (PC) remains elusive, given conflicting data on their association with disease prognosis. In this study, using conventional K562 target cells and complementary engineered target cells providing defined and synergistic stimulation for NK cell activation, a correlation between impaired NK cell cytotoxic degranulation and PC progression was determined. Peripheral blood mononuclear cells (PBMCs) from 31 patients with newly diagnosed PC, 24 patients with non-malignant tumors, and 37 healthy controls were analyzed by flow cytometry. The frequency, phenotype, and effector functions of the NK cells were evaluated, and correlations between NK cell functions and disease stage and prognosis were analyzed. The results demonstrated that effector functions, but not frequency, of NK cells was progressively decreased on a per-cell basis during PC progression. Impaired cytotoxic degranulation, but not IFN-γ production, was associated with clinical features indicating disease progression, such as high serum CA19-9 and high-grade tumors. Significantly, this impairment correlated with cancer recurrence and mortality in a prospective analysis. Furthermore, the impaired cytotoxic degranulation was unrelated to NKG2D downregulation but was associated with increased circulating and tumor-associated TGF-β1 expression. Thus, NK cell cytotoxic activity was associated with PC progression and may be a favorable biomarker with predictive and prognostic value in PC.
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http://dx.doi.org/10.3389/fimmu.2019.01354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6598013PMC
October 2020

The role of CIP2A as a therapeutic target of rapamycin in radioresistant head and neck cancer with TP53 mutation.

Head Neck 2019 09 3;41(9):3362-3371. Epub 2019 Jul 3.

Department of Otolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Republic of Korea.

Background: CIP2A may activate multiple oncogenic proteins and promote the proliferation of various cancer cells.

Methods: We investigated that the role of CIP2A in radioresistant head and neck cancer (HNC) cell line with TP53 mutation and the effect of the rapamycin on the response of HN31 with TP53 mutation cells to irradiation related to CIP2A expression.

Results: CIP2A expression was stimulated by p53 mutation and critical for the inhibition of senescence induction in response to radiation. The treatment with radiation alone neither induced cytotoxicity in HN31 cells nor completely suppressed the activation of CIP2A. However, the combination of radiation and rapamycin increase the radiosensitivity through the induction of senescence with downregulation of CIP2A expression both in vivo and in vitro.

Conclusion: Our results suggest that CIP2A may serve as a therapeutic target of rapamycin through induction of senescence in radioresistant HNC with TP53 mutation.
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http://dx.doi.org/10.1002/hed.25868DOI Listing
September 2019

Links between accelerated replicative cellular senescence and down-regulation of SPHK1 transcription.

BMB Rep 2019 Mar;52(3):220-225

Departments of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul 05505, Korea.

We have identified a mechanism to diminish the proliferative capacity of cells during cell expansion using human adiposederived stromal cells (hAD-SCs) as a model of replicative senescence. hAD-SCs of high-passage numbers exhibited a reduced proliferative capacity with accelerated cellular senescence. Levels of key bioactive sphingolipids were significantly increased in these senescent hAD-SCs. Notably, the transcription of sphingosine kinase 1 (SPHK1) was down-regulated in hAD-SCs at high-passage numbers. SPHK1 knockdown as well as inhibition of its enzymatic activity impeded the proliferation of hAD-SCs, with concomitant induction of cellular senescence and accumulation of sphingolipids, as seen in high-passage cells. SPHK1 knockdown-accelerated cellular senescence was attenuated by co-treatment with sphingosine-1-phosphate and an inhibitor of ceramide synthesis, fumonisin B1, but not by treatment with either one alone. Together, these results suggest that transcriptional down-regulation of SPHK1 is a critical inducer of altered sphingolipid profiles and enhances replicative senescence during multiple rounds of cell division. [BMB Reports 2019; 52(3): 220-225].
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6476483PMC
March 2019

p53/BNIP3-dependent mitophagy limits glycolytic shift in radioresistant cancer.

Oncogene 2019 05 21;38(19):3729-3742. Epub 2019 Jan 21.

Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

The role of p53 in genotoxic therapy-induced metabolic shift in cancers is not yet known. In this study, we investigated the role of p53 in the glycolytic shift in head and neck squamous cell carcinoma cell lines following irradiation. Isogenic p53-null radioresistant cancer cells established through cumulative irradiation showed decreased oxygen consumption and increased glycolysis with compromised mitochondria, corresponding with their enhanced sensitivity to drugs that target glycolysis. In contrast, radioresistant cancer cells with wild-type p53 preserved their primary metabolic profile with intact mitophagic processes and maintained their mitochondrial integrity. Moreover, we identified a previously unappreciated link between p53 and mitophagy, which limited the glycolytic shift through the BNIP3-dependent clearance of abnormal mitochondria. Thus, drugs targeting glycolysis could be used as an alternative strategy for overcoming radioresistant cancers, and the p53 status could be used as a biomarker for selecting participants for clinical trials.
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http://dx.doi.org/10.1038/s41388-019-0697-6DOI Listing
May 2019

Endothelial dysfunction induces atherosclerosis: increased aggrecan expression promotes apoptosis in vascular smooth muscle cells.

BMB Rep 2019 Feb;52(2):145-150

Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine; Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine; Stem Cell Immunomodulation Research Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.

Endothelial dysfunction-induced lipid retention is an early feature of atherosclerotic lesion formation. Apoptosis of vascular smooth muscle cells (VSMCs) is one of the major modulating factors of atherogenesis, which accelerates atherosclerosis progression by causing plaque destabilization and rupture. However, the mechanism underlying VSMC apoptosis mediated by endothelial dysfunction in relation to atherosclerosis remains elusive. In this study, we reveal differential expression of several genes related to lipid retention and apoptosis, in conjunction with atherosclerosis, by utilizing a genetic mouse model of endothelial nitric oxide synthase (eNOS) deficiency manifesting endothelial dysfunction. Moreover, eNOS deficiency led to the enhanced susceptibility against pro-apoptotic insult in VSMCs. In particular, the expression of aggrecan, a major proteoglycan, was elevated in aortic tissue of eNOS deficient mice compared to wild type mice, and administration of aggrecan induced apoptosis in VSMCs. This suggests that eNOS deficiency may elevate aggrecan expression, which promotes apoptosis in VSMC, thereby contributing to atherosclerosis progression. These results may facilitate the development of novel approaches for improving the diagnosis or treatment of atherosclerosis. [BMB Reports 2019; 52(2): 145-150].
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443320PMC
February 2019

MicroRNA expression profiling of adult hippocampal neural stem cells upon cell death reveals an autophagic cell death-like pattern.

Biochem Biophys Res Commun 2019 02 3;509(3):674-679. Epub 2019 Jan 3.

Department of Microbiology, University of Ulsan College of Medicine, Seoul, South Korea; Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, South Korea. Electronic address:

Adult hippocampal neural (HCN) stem cells promptly undergo irreversible autophagic cell death (ACD) if deprived of insulin in culture. Small, non-coding microRNAs (miRNA) play an important role in regulating biological processes, including proliferation and cell death. However, there have been no reports thus far regarding miRNA involvement in the induction of adult HCN stem cell death under insulin-deprived conditions, for which we performed a microarray-based analysis to examine the expression signature of miRNAs in adult rat HCN stem cells. Three independent specimens per culture condition either with or without insulin were prepared and a miRNA microarray analysis carried out. A total of 12 exhibited significantly altered expression levels upon cell death due to the absence of insulin when compared to HCN stem cells cultured with insulin present (cut-off limit; p < 0.05 and fold-change >1.3) The resulting volcano plot showed that, among these miRNAs, seven were upregulated and five were downregulated. The upregulated miRNAs were capable of modulating HCN stem cell death. Caspase-3 activity analysis, LC3 conversion, and TEM of autophagosome formation consistently suggested that ACD, not apoptosis, was most likely the mechanism affecting HCN cell death. As such, we have come to term these miRNAs, "HCN stem cell-specific autophagic cell death regulators." Taken together, our data suggest that the miRNA expression profile of HCN stem cells is altered during ACD occurring due to insulin deprivation and that differentially expressed miRNAs are involved in HCN stem cell viability. Detailed explorations of the underlying mechanisms regarding HCN stem cell viability modulation by these miRNAs would be beneficial in further understanding the physiological features of adult HCN stem cells and are currently being investigated.
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http://dx.doi.org/10.1016/j.bbrc.2018.12.157DOI Listing
February 2019

Human umbilical cord blood mesenchymal stem cells expansion via human fibroblast-derived matrix and their potentials toward regenerative application.

Cell Tissue Res 2019 May 4;376(2):233-245. Epub 2019 Jan 4.

Center for Biomaterials, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea.

Large expansion of human mesenchymal stem cells (MSCs) is of great interest for clinical applications. In this study, we examine the feasibility of human fibroblast-derived extracellular matrix (hFDM) as an alternative cell expansion setting. hFDM is obtained from decellularized extracellular matrix (ECM) derived from in vitro cultured human lung fibroblasts. Our study directly compares conventional platforms (tissue culture plastic (TCP), fibronectin (FN)-coated TCP) with hFDM using umbilical cord blood-derived MSCs (UCB-MSCs). Early cell morphology shows a rather rounded shape on TCP but highly elongated morphology on hFDM. Cell proliferation demonstrates that MSCs on hFDM were significantly better compared to the others in both 10 and 2% serum condition. Cell migration assay suggests that cell motility was improved and a cell migration marker CXCR4 was notably up-regulated on hFDM. MSCs differentiation into osteogenic lineage on hFDM was also very effective as examined via gene expression, von Kossa staining and alkaline phosphatase activity. In addition, as the MSCs were expanded on each substrate, transferred to 3D polymer mesh scaffolds and then cultivated for a while, the data found better cell proliferation and more CXCR4 expression with MSCs pre-conditioned on hFDM. Moreover, higher gene expression of stemness and engraftment-related markers was noticed with the hFDM group. Furthermore when UCB-MSCs expanded on TCP or hFDM were injected into emphysema (a lung disease) animal model, the results indicate that MSCs pre-conditioned on hFDM (with 2% serum) retain more advanced therapeutic efficacy on the improvement of emphysema than those on TCP. Current works demonstrate that compared to the conventional platforms, hFDM can be a promising source of cell expansion with a naturally derived biomimetic ECM microenvironment and may find some practical applications in regenerative medicine.
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http://dx.doi.org/10.1007/s00441-018-2971-2DOI Listing
May 2019

Elevated Pentraxin 3 in Obese Adipose Tissue Promotes Adipogenic Differentiation by Activating Neuropeptide Y Signaling.

Front Immunol 2018 30;9:1790. Epub 2018 Jul 30.

Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Obesity is accompanied by chronic systemic inflammation characterized by macrophage infiltration of obese tissues, an elevated plasma level of inflammatory substances, and excessive accumulation of lipids. The pro-inflammatory factor pentraxin 3 (PTX3) is also elevated in obese tissues, suggesting its potential role in adipogenesis. We found by analyzing murine preadipocyte 3T3-L1 cells, and human adipocytes derived from mesenchymal stem cells, which locally elevated PTX3 in obese adipose tissue augments adipocyte differentiation and subsequent lipid accumulation. This occurs the upregulation of adipogenesis-related transcription factors. PTX3 enhanced lipid accumulation in murine 3T3-L1 cells by upregulating the expression of neuropeptide Y (NPY)/NPY receptor (NPYR) expression in preadipocytes. Pharmacological inhibition by NPYR antagonists abolished these effects. NPY also promoted the production of reactive oxygen species (ROS), a known trigger of adipogenesis. NPYR antagonists as well as antioxidant -acetylcysteine showed anti-adipogenic effects by reducing the ROS levels, indicating that PTX3 mediates adipogenesis through NPY-dependent ROS production. These findings suggest that PTX3 plays a key role in the development of obesity by enhancing adipocyte differentiation and lipid synthesis NPY/NPYR signaling. These observations provide a mechanistic explanation for the adipogenesis mediated by PTX3.
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http://dx.doi.org/10.3389/fimmu.2018.01790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6077621PMC
September 2019

Self-Triggered Apoptosis Enzyme Prodrug Therapy (STAEPT): Enhancing Targeted Therapies via Recurrent Bystander Killing Effect by Exploiting Caspase-Cleavable Linker.

Adv Sci (Weinh) 2018 Jul 5;5(7):1800368. Epub 2018 Jun 5.

Research Institute of Pharmaceutical Sciences College of Pharmacy Seoul National University Seoul 08826 South Korea.

Tumor heterogeneity is associated with the therapeutic failures of targeted therapies. To overcome such heterogeneity, a novel targeted therapy is proposed that could kill tumor populations with diverse phenotypes by delivering nonselective cytotoxins to target-positive cells as well as to the surrounding tumor cells via a recurrent bystander killing effect. A representative prodrug is prepared that targets integrin αvβ3 and releases cytotoxins upon entering cells or by caspase-3. This allows the prodrug to kill integrin αvβ3-positive cells and upregulate caspase-3, which in turn, activates the prodrug to release a cytotoxin that could subsequently diffuse into and kill the neighboring tumor cells. Apoptotic cells further upregulate and release caspase-3, which activate more prodrugs leading to another round of adjacent cell death and caspase-3 release. Thus, the bystander killing effect could occur repeatedly, leading to augmented and widespread anticancer activity. This strategy provides an avenue that could advance the current targeted therapy.
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http://dx.doi.org/10.1002/advs.201800368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6051143PMC
July 2018

EphA3 maintains radioresistance in head and neck cancers through epithelial mesenchymal transition.

Cell Signal 2018 Jul 10;47:122-130. Epub 2018 Apr 10.

Department of Otolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Republic of Korea. Electronic address:

Radiotherapy is a well-established therapeutic modality used in the treatment of many cancers. However, radioresistance remains a serious obstacle to successful treatment. Radioresistance can cause local recurrence and distant metastases in some patients after radiation treatment. Thus, many studies have attempted to identify effective radiosensitizers. Eph receptor functions contribute to tumor development, modulating cell-cell adhesion, invasion, neo-angiogenesis, tumor growth and metastasis. However, the role of EphA3 in radioresistance remains unclear. In the current study, we established a stable radioresistant head and neck cancer cell line (AMC HN3R cell line) and found that EphA3 was expressed predominantly in the radioresistant head and neck cancer cell line through DNA microarray, real time PCR and Western blotting. Additionally, we found that EphA3 was overexpressed in recurrent laryngeal cancer specimens after radiation therapy. EphA3 mediated the tumor invasiveness and migration in radioresistant head and neck cancer cell lines and epithelial mesenchymal transition- related protein expression. Inhibition of EphA3 enhanced radiosensitivity in the AMC HN 3R cell line in vitro and in vivo study. In conclusion, our results suggest that EphA3 is overexpressed in radioresistant head and neck cancer and plays a crucial role in the development of radioresistance in head and neck cancers by regulating the epithelial mesenchymal transition pathway.
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http://dx.doi.org/10.1016/j.cellsig.2018.04.001DOI Listing
July 2018

Phosphorylation of PI3K regulatory subunit p85 contributes to resistance against PI3K inhibitors in radioresistant head and neck cancer.

Oral Oncol 2018 03 20;78:56-63. Epub 2018 Feb 20.

Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address:

Objectives: PI3K/Akt/mTOR pathway is commonly activated in most cancers and is correlated with resistance to anticancer therapies such as radiotherapy. Therefore, PI3K is an attractive target for treating PI3K-associated cancers.

Material And Methods: We investigated the basal expression and the expression after treatment of PI3K inhibitor or Src inhibitor of PI3K/Akt pathway-related proteins in AMC-HN3, AMC-HN3R, HN30 and HN31 cells by performing immunoblotting analysis. The sensitivity to PI3K inhibitors or Src inhibitor was analyzed by MTT assay and clonogenic assay. To determine the antitumoral activity of combination treatment with PI3K inhibitor and Src inhibitor, we used using xenograft mouse model.

Results: We found that PI3K regulatory subunit p85 was predominantly phosphorylated in radioresistant head and neck cancer cell line (HN31), which showed resistance to PI3K inhibitors. Next, we investigated mechanism through which PI3K p85 phosphorylation modulated response to PI3K inhibitors. Of note, constitutive activation of Src was found in HN31 cells and upon PI3K inhibitor treatment, restoration of p-Src was occurred. Src inhibitor improved the efficacy of PI3K inhibitor treatment and suppressed the reactivation of both Src and PI3K p85 in HN31 cells. Furthermore, downregulation of PI3K p85 expression by using a specific siRNA suppressed Src phosphorylation.

Conclusions: Together, our results imply the novel role of the PI3K regulatory subunit p85 in the development of resistance to PI3K inhibitors and suggest the presence of a regulatory loop between PI3K p85 and Src in radioresistant head and neck cancers with constitutively active PI3K/Akt pathway.
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http://dx.doi.org/10.1016/j.oraloncology.2018.01.014DOI Listing
March 2018

Small molecule-based lineage switch of human adipose-derived stem cells into neural stem cells and functional GABAergic neurons.

Sci Rep 2017 08 31;7(1):10166. Epub 2017 Aug 31.

Lab. of Stem Cell & Neurobiology, Department of Oral Anatomy, Dental Research Institute and School of Dentistry, Seoul National University, Seoul, 03080, Republic of Korea.

Cellular reprogramming using small molecules (SMs) without genetic modification provides a promising strategy for generating target cells for cell-based therapy. Human adipose-derived stem cells (hADSCs) are a desirable cell source for clinical application due to their self-renewal capacity, easy obtainability and the lack of safety concerns, such as tumor formation. However, methods to convert hADSCs into neural cells, such as neural stem cells (NSCs), are inefficient, and few if any studies have achieved efficient reprogramming of hADSCs into functional neurons. Here, we developed highly efficient induction protocols to generate NSC-like cells (iNSCs), neuron-like cells (iNs) and GABAergic neuron-like cells (iGNs) from hADSCs via SM-mediated inhibition of SMAD signaling without genetic manipulation. All induced cells adopted morphological, molecular and functional features of their bona fide counterparts. Electrophysiological data demonstrated that iNs and iGNs exhibited electrophysiological properties of neurons and formed neural networks in vitro. Microarray analysis further confirmed that iNSCs and iGNs underwent lineage switch toward a neural fate. Together, these studies provide rapid, reproducible and robust protocols for efficient generation of functional iNSCs, iNs and iGNs from hADSCs, which have utility for modeling disease pathophysiology and providing cell-therapy sources of neurological disorders.
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http://dx.doi.org/10.1038/s41598-017-10394-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579051PMC
August 2017

Phosphorylation of p62 by AMP-activated protein kinase mediates autophagic cell death in adult hippocampal neural stem cells.

J Biol Chem 2017 08 27;292(33):13795-13808. Epub 2017 Jun 27.

From the Department of Brain and Cognitive Sciences and

In the adult brain, programmed death of neural stem cells is considered to be critical for tissue homeostasis and cognitive function and is dysregulated in neurodegeneration. Previously, we have reported that adult rat hippocampal neural (HCN) stem cells undergo autophagic cell death (ACD) following insulin withdrawal. Because the apoptotic capability of the HCN cells was intact, our findings suggested activation of unique molecular mechanisms linking insulin withdrawal to ACD rather than apoptosis. Here, we report that phosphorylation of autophagy-associated protein p62 by AMP-activated protein kinase (AMPK) drives ACD and mitophagy in HCN cells. Pharmacological inhibition of AMPK or genetic ablation of the AMPK α2 subunit by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing suppressed ACD, whereas AMPK activation promoted ACD in insulin-deprived HCN cells. We found that following insulin withdrawal AMPK phosphorylated p62 at a novel site, Ser-293/Ser-294 (in rat and human p62, respectively). Phosphorylated p62 translocated to mitochondria and induced mitophagy and ACD. Interestingly, p62 phosphorylation at Ser-293 was not required for staurosporine-induced apoptosis in HCN cells. To the best of our knowledge, this is the first report on the direct phosphorylation of p62 by AMPK. Our data suggest that AMPK-mediated p62 phosphorylation is an ACD-specific signaling event and provide novel mechanistic insight into the molecular mechanisms in ACD.
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http://dx.doi.org/10.1074/jbc.M117.780874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566532PMC
August 2017

Radiotherapy-assisted tumor selective metronomic oral chemotherapy.

Int J Cancer 2017 11 2;141(9):1912-1920. Epub 2017 Aug 2.

Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul, South Korea.

Chemotherapy have commonly been used in maximum tolerated dose to completely eradicate the cancer. However, such treatments often failed due to the complex and dynamic nature of cancer. Therefore, it has been suggested that cancer should be treated as a chronic disease, controlling its growth by providing continuous therapeutic pressure for long-term. Such an approach, however, requires a therapy that is non-toxic and orally available with sufficient potency. Herein, we propose a radiotherapy-assisted orally available metronomic apoptosis-targeted chemotherapy, which delivers doxorubicin continuously to the irradiated tumor with high selectivity while causing minimal toxicities to the normal tissues. DEVD-S-DOX/DCK complex is the anticancer prodrug for our strategy that could selectively release doxorubicin in the irradiated tumor tissue with sufficient oral bioavailability. The prodrug was completely inactive by itself, but displayed potent anticancer activity when coupled with radiotherapy. Consequently, the daily oral administration of DEVD-S-DOX/DCK in combination with the low-dose radiotherapy effectively suppressed the growth of tumor in vivo with no significant systemic toxicities despite that the accumulated dose of doxorubicin exceeded 150 mg/kg. Therefore, the our novel therapy using DEVD-S-DOX/DCK complex is considered as an outstanding treatment option for treating cancer for long-term attributed to its oral availability and low-toxicity profile as well as the potent anticancer effect.
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http://dx.doi.org/10.1002/ijc.30842DOI Listing
November 2017

Angiotensin II Causes Apoptosis of Adult Hippocampal Neural Stem Cells and Memory Impairment Through the Action on AMPK-PGC1α Signaling in Heart Failure.

Stem Cells Transl Med 2017 06 28;6(6):1491-1503. Epub 2017 Feb 28.

Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Data are limited on the mechanisms underlying memory impairment in heart failure (HF). We hypothesized that angiotensin II (Ang II) may determine the fate of adult hippocampal neural stem cells (HCNs), a cause of memory impairment in HF. HCNs with neurogenesis potential were isolated and cultured from adult rat hippocampi. Ang II decreased HCN proliferation in dose- and time-dependent manners. Moreover, Ang II treatment (1 µM) for 48 hours induced apoptotic death, which was attenuated by pretreatment with Ang II receptor blockers (ARBs). Ang II increased mitochondrial reactive oxygen species (ROS) levels, which was related to mitochondrial morphological changes and functional impairment. Moreover, ROS activated the AMP-activated protein kinase (AMPK) and consequent peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) expression, causing cell apoptosis. In the HF rat model induced by left anterior descending artery ligation, ARB ameliorated the spatial memory ability which decreased 10 weeks after ischemia. In addition, neuronal cell death, especially of newly born mature neurons, was observed in HF rat hippocampi. ARB decreased cell death and promoted the survival of newly born neural precursor cells and mature neurons. In conclusion, Ang II caused HCN apoptosis through mitochondrial ROS formation and subsequent AMPK-PGC1α signaling. ARB improved learning and memory behaviors impaired by neuronal cell death in the HF animal model. These findings suggest that HCN is one treatment target for memory impairment in HF and that ARBs have additional benefits in HF combined with memory impairment. Stem Cells Translational Medicine 2017;6:1491-1503.
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http://dx.doi.org/10.1002/sctm.16-0382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5689768PMC
June 2017

Enhanced axonal regeneration by transplanted Wnt3a-secreting human mesenchymal stem cells in a rat model of spinal cord injury.

Acta Neurochir (Wien) 2017 05 3;159(5):947-957. Epub 2017 Feb 3.

Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea.

Background: While pure mesenchymal stem cell (MSC) treatment for spinal cord injury (SCI) is known to be safe, its efficacy is insufficient. Therefore, gene-modified stem cells are being developed to enhance the effect of pure MSCs. We investigated the effect of stem cell therapy through the transfection of a Wnt3a-producing gene that stimulates axonal regeneration.

Method: MSCs obtained from the human umbilical cord blood (hMSCs) were multiplied, cultivated, and transfected with the pLenti-Wnt3a-GFP viral vector to produce Wnt3a-secreting hMSCs. A total of 50 rats were injured with an Infinite Horizon impactor at the level of the T7-8 vertebrae. Rats were divided into five groups according to the transplanted material: (1) phosphate-buffered saline injection group (sham group, n = 10); (Pertz et al. Proc Natl Acad Sci USA 105:1931-1936, 39) Wnt3a protein injection group (Wnt3a protein group, n = 10); (3) hMSC transplantation group (MSC group, n = 10); (4) hMSCs transfected with the pLenti vector transplantation group (pLenti-MSC group, n = 10); (5) hMSCs transfected with the pLenti+Wnt3a vector transplantation group (Wnt3a-MSC group, n = 10). Behavioral tests were performed daily for the first 3 days after injury and then weekly for 8 weeks. The injured spinal cords were extracted, and axonal regeneration markers including choline acetyltransferase (ChAT), growth-associated protein 43 (GAP43), and microtubule-associated protein 2 (MAP2) were investigated by immunofluorescence, RT-PCR, and western blotting.

Results: Seven weeks after the transplantation (8 weeks after SCI), rats in the Wnt3a-MSC group achieved significantly higher average scores in the motor behavior tests than those in the other groups (p < 0.05). Immunofluorescent stains showed greater immunoreactivity of ChAT, GAP43, and MAP2 in the Wnt3a-MSC group than in the other groups. RT-PCR and western blots revealed greater expression of these proteins in the Wnt3a-MSC group than in the other groups (p < 0.05).

Conclusions: Wnt3a-secreting hMSC transplantation considerably improved neurological recovery and axonal regeneration in a rat SCI model.
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http://dx.doi.org/10.1007/s00701-017-3097-0DOI Listing
May 2017

hMSCs suppress neutrophil-dominant airway inflammation in a murine model of asthma.

Exp Mol Med 2017 01 27;49(1):e288. Epub 2017 Jan 27.

Division of Allergy and Clinical Immunology, Department of Internal Medicine, ASAN Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Although chronic eosinophilic inflammation is a common feature in patients with asthma, some patients have neutrophil-dominant inflammation, which is known to be associated with severe asthma.Human mesenchymal stem cells (hMSCs) have shown promise in treating various refractory immunological diseases. Thus, hMSCs may represent an alternative therapeutic option for asthma patients with neutrophil-dominant inflammation, in whom current treatments are ineffective. BALB/c mice exposed to ovalbumin and polyinosinic:polycytidylic acid (Poly I:C) to induce neutrophilic airway inflammation were systemically treated with hMSCs to examine whether the hMSCs can modulate neutrophilic airway inflammation. In addition, cytokine production was evaluated in co-cultures of hMSCs with either anti-CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) obtained from asthmatic patients or cells of the human bronchial epithelial cell line BEAS-2B to assess the response to hMSC treatment. The total number of immune cells in bronchoalveolar lavage fluid (BALF) showed a dramatic decrease in hMSC-treated asthmatic mice, and, in particular, neutrophilic infiltration was significantly attenuated. This phenomenon was accompanied by reduced CXCL15 production in the BALF. BEAS-2B cells co-cultured with hMSCs showed reduced secretion of IL-8. Moreover, decreased secretion of IL-4, IL-13 and IFN-γ was observed when human PBMCs were cultured with hMSCs, whereas IL-10 production was greatly enhanced. Our data imply that hMSCs may have a role in reducing neutrophilic airway inflammation by downregulating neutrophil chemokine production and modulating T-cell responses.
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http://dx.doi.org/10.1038/emm.2016.135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291839PMC
January 2017

Metronomic chemotherapy using orally active carboplatin/deoxycholate complex to maintain drug concentration within a tolerable range for effective cancer management.

J Control Release 2017 03 16;249:42-52. Epub 2017 Jan 16.

Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742, South Korea; Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea. Electronic address:

Metronomic chemotherapy has translated into favorable toxicity profile and capable of delaying tumor progression. Despite its promise, conventional injectable chemotherapeutics are not meaningful to use as metronomic due to the necessity of frequent administration for personalized therapy in long-term cancer treatments. This study aims to exploit the benefits of the oral application of carboplatin as metronomic therapy for non-small cell lung cancer (NSCLC). We developed an orally active carboplatin by physical complexation with a deoxycholic acid (DOCA). The X-ray diffraction (XRD) patterns showed the disappearance of crystalline peaks from carboplatin by forming the complex with DOCA. In vivo pharmacokinetic (PK) study confirmed the oral absorption of carboplatin/DOCA complex. The oral bioavailability of carboplatin/DOCA complex and native carboplatin were calculated as 24.33% and 1.16%, respectively, when a single 50mg/kg oral dose was administered. Further findings of oral bioavailability during a low-dose daily administration of the complex (10mg/kg) for 3weeks were showed 19.17% at day-0, 30.27% at day-7, 26.77% at day-14, and 22.48% at day-21, demonstrating its potential for metronomic chemotherapy. The dose dependent antitumor effects of oral carboplatin were evaluated in SCC7 and A549 tumor xenograft mice. It was found that the oral carboplatin complex exhibited potent anti-tumor activity at 10mg/kg (74.09% vs. control, P<0.01) and 20mg/kg dose (86.22% vs. control, P<0.01) in A549 tumor. The number of TUNEL positive cells in the tumor sections was also significantly increased during oral therapy (3.95% in control, whereas 21.37% and 32.39% in 10mg/kg and 20mg/kg dose, respectively; P<0.001). The enhanced anti-tumor efficacy of oral metronomic therapy was attributed with its antiangiogenic mechanism where new blood vessel formation was notably decreased. Finally, the safety of oral complex was confirmed by three weeks toxicity studies; there were no significant systemic or local abnormalities found in mice at 10mg/kg daily oral dose. Our study thus describes an effective and safe oral formulation of carboplatin as a metronomic chemotherapy.
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http://dx.doi.org/10.1016/j.jconrel.2017.01.020DOI Listing
March 2017
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