• Journal of Life Science
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• v.23 no.9
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• pp.1177-1182
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• 2013

Trichinella spiralis (T. spiralis) has been reported to induce angiogenesis and a supply of nutrients and to act as a reliable waste disposal system by induction of the expression of the angiogenic molecule vascular endothelial cell growth factor (VEGF) during nurse cell formation. However, the mechanism underlying the induction of VEGF in nurse cells by T. spiralis has not yet been defined. Some research has pointed to the possibility of hypoxia in nurse cells, but whether hypoxia occurs in infected muscle or nurse cells has not been studied. It is also a matter of debate whether hypoxia induces the expression of VEGF and subsequent angiogenesis in infected muscle. Recent studies showed that thymosin ${\beta}4$, a potent VEGF-inducing protein, was expressed at a very early stage of muscle infection by T. spiralis, suggesting that VEGF is induced at an early stage in nurse cells. Furthermore, hypoxia was not detected in any nurse cell stage but was detected in inflammatory cells. The findings suggest that induction of angiogenesis by VEGF in T. spiralis-infected nurse cells is mediated by thymosin ${\beta}4$ and unrelated to hypoxia.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.2
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• pp.173-183
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• 2020

An in vitro model for ischemia/reperfusion injury has not been well-established. We hypothesized that this failure may be caused by serum deprivation, the use of glutamine-containing media, and absence of acidosis. Cell viability of H9c2 cells was significantly decreased by serum deprivation. In this condition, reperfusion damage was not observed even after simulating severe ischemia. However, when cells were cultured under 10% dialyzed FBS, cell viability was less affected compared to cells cultured under serum deprivation and reperfusion damage was observed after hypoxia for 24 h. Reperfusion damage after glucose or glutamine deprivation under hypoxia was not significantly different from that after hypoxia only. However, with both glucose and glutamine deprivation, reperfusion damage was significantly increased. After hypoxia with lactic acidosis, reperfusion damage was comparable with that after hypoxia with glucose and glutamine deprivation. Although high-passage H9c2 cells were more resistant to reperfusion damage than low-passage cells, reperfusion damage was observed especially after hypoxia and acidosis with glucose and glutamine deprivation. Cell death induced by reperfusion after hypoxia with acidosis was not prevented by apoptosis, autophagy, or necroptosis inhibitors, but significantly decreased by ferrostatin-1, a ferroptosis inhibitor, and deferoxamine, an iron chelator. These data suggested that in our SIR model, cell death due to reperfusion injury is likely to occur via ferroptosis, which is related with ischemia/reperfusion-induced cell death in vivo. In conclusion, we established an optimal reperfusion injury model, in which ferroptotic cell death occurred by hypoxia and acidosis with or without glucose/glutamine deprivation under 10% dialyzed FBS.

• The Journal of Korean Medicine
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• v.25 no.2
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• pp.67-76
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• 2004

Objectives : This study was designed to investigate the protective mechanisms of Palmul-tang on hypoxia-induced cytotoxicity in H9c2 cardiomyoblast cells. Methods : In this study, we used H9c2 cells. Cells were subjected to hypoxia in the absence and presence of $1000\mu\textrm{g}/ml$ Palmul-tang for 24 hrs. Cells were treated with various concentrations of Palmul-tang for 24 hrs. Cell viability was measured by MTT assay. Hypoxia markedly decreased the viability of H9c2 cells, which was characterized with apparent apoptotic features such as chromatin condensation as well as fragmentation of genomic DNA and nuclei. Results : Palmul-tang significantly reduced hypoxia-induced cell death and apoptotic characteristics. Also, Palmul-tang prevented mitochondrial dysfunction including the disruption of mitochondrial membrane permeability transition (MPT) and an increase in expression of apoptogenic Bcl-2 proteins in hypoxia-H9c2 cells. Conclusions; This study suggests that the protective effects of Palmul-tang against hypoxic damages may be mediated by the modulation of Bcl-2, Bax expression.

• Molecules and Cells
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• v.37 no.9
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• pp.637-643
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• 2014

Wound healing is a complex multi-step process that requires spatial and temporal orchestration of cellular and non-cellular components. Hypoxia is one of the prominent microenvironmental factors in tissue injury and wound healing. Hypoxic responses, mainly mediated by a master transcription factor of oxygen homeostasis, hypoxia-inducible factor-1 (HIF-1), have been shown to be critically involved in virtually all processes of wound healing and remodeling. Yet, mechanisms underlying hypoxic regulation of wound healing are still poorly understood. Better understanding of how the wound healing process is regulated by the hypoxic microenvironment and HIF-1 signaling pathway will provide insight into the development of a novel therapeutic strategy for impaired wound healing conditions such as diabetic wound and fibrosis. In this review, we will discuss recent studies illuminating the roles of HIF-1 in physiologic and pathologic wound repair and further, the therapeutic potentials of HIF-1 stabilization or inhibition.

• Korean Journal of Pharmacognosy
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• v.36 no.2 s.141
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• pp.151-157
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• 2005

This research was performed to investigate the protective effect of Chungpesagan-tang (CST) from hypoxia/reperfusion induced-PC12 cell damage. To elucidate the mechanism of the protective effect of CST, cell viability, changes in activities of superoxide dismutase, glutathione peroxidase, catalase, caspase 3 and the production of malondialdehyde were observed after treating PC12 cells with CST which was metabolized by rat liver homogenate. Pretreatment of CST with liver homogenate appeared to increase its protective effect against hypoxia/reperfusion insult. The result showed that CST exhibited the highest protective effect against hypoxia/reperfusion at the dose of $1\;{\mu}g/ml$ in PC12 cells, probably by recovering the redox enzyme activities and MDA to control level.

• Biomolecules & Therapeutics
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• v.30 no.5
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• pp.465-472
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• 2022

Melanoma is one of the most aggressive skin cancers. Hypoxia contributes to the aggressiveness of melanoma by promoting cancer growth and metastasis. Upregulation of cyclin D1 can promote uncontrolled cell proliferation in melanoma, whereas stimulation of cytotoxic T cell activity can inhibit it. Epithelial mesenchymal transition (EMT) plays a critical role in melanoma metastasis. Hypoxia-inducible factor-1α (HIF-1α) is a main transcriptional mediator that regulates many genes related to hypoxia. CoCl₂ is one of the most commonly used hypoxia-mimetic chemicals in cell culture. In this study, inhibitory effects of IDF-11774, an inhibitor of HIF-1α, on melanoma growth and metastasis were examined using cultured B16F10 mouse melanoma cells and nude mice transplanted with B16F10 melanoma cells in the presence or absence of CoCl₂-induced hypoxia. IDF-11774 reduced HIF-1α upregulation and cell survival, but increased cytotoxicity of cultured melanoma cells under CoCl₂-induced hypoxia. IDF-11774 also reduced tumor size and local invasion of B16F10 melanoma in nude mice along with HIF-1α downregulation. Expression levels of cyclin D1 in melanoma were increased by CoCl₂ but decreased by IDF-11774. Apoptosis of melanoma cells and infiltration of cytotoxic T cells were increased in melanoma after treatment with IDF-11774. EMT was stimulated by CoCl₂, but restored by IDF11774. Overall, IDF-11774 inhibited the growth and metastasis of B16F10 melanoma via HIF-1α downregulation. The growth of B16F10 melanoma was inhibited by cyclin D1 downregulation and cytotoxic T cell stimulation. Metastasis of B16F10 melanoma was inhibited by EMT suppression.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.2
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• pp.203-213
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• 2018

Tumor undergo uncontrolled, excessive proliferation leads to hypoxic microenvironment. To fulfill their demand for nutrient, and oxygen, tumor angiogenesis is required. Endothelial progenitor cells (EPCs) have been known to the main source of angiogenesis because of their potential to differentiation into endothelial cells. Therefore, understanding the mechanism of EPC-mediated angiogenesis in hypoxia is critical for development of cancer therapy. Recently, mitochondrial dynamics has emerged as a critical mechanism for cellular function and differentiation under hypoxic conditions. However, the role of mitochondrial dynamics in hypoxia-induced angiogenesis remains to be elucidated. In this study, we demonstrated that hypoxia-induced mitochondrial fission accelerates EPCs bioactivities. We first investigated the effect of hypoxia on EPC-mediated angiogenesis. Cell migration, invasion, and tube formation was significantly increased under hypoxic conditions; expression of EPC surface markers was unchanged. And mitochondrial fission was induced by hypoxia time-dependent manner. We found that hypoxia-induced mitochondrial fission was triggered by dynamin-related protein Drp1, specifically, phosphorylated DRP1 at Ser637, a suppression marker for mitochondrial fission, was impaired in hypoxia time-dependent manner. To confirm the role of DRP1 in EPC-mediated angiogenesis, we analyzed cell bioactivities using Mdivi-1, a selective DRP1 inhibitor, and DRP1 siRNA. DRP1 silencing or Mdivi-1 treatment dramatically reduced cell migration, invasion, and tube formation in EPCs, but the expression of EPC surface markers was unchanged. In conclusion, we uncovered a novel role of mitochondrial fission in hypoxia-induced angiogenesis. Therefore, we suggest that specific modulation of DRP1-mediated mitochondrial dynamics may be a potential therapeutic strategy in EPC-mediated tumor angiogenesis.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.1
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• pp.36-47
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• 2019

Hypoxia-inducible factor-1 ($HIF-1{\alpha}$) is a transcription factor activated in response to low oxygen level, and is highly expressed in many solid tumors. Moreover, $HIF-1{\alpha}$ is a representative biomarker of hypoxia and also helps to maintain cell homeostasis under hypoxic condition. Most solid tumors show hypoxia, which induces poor prognosis and resistance to conventional cancer therapies. Thus, early diagnosis of hypoxia with positron emission tomography (PET) radiotracer would be highly beneficial for management of malignant solid tumors with effective cancer therapy. YC-1 is a most promising candidate among several $HIF-1{\alpha}$ inhibitors. As an effort to develop a hypoxia imaging tool as a PET radiotracer, we designed and synthesized [$^{18}F$]DFYC based on potent derivative of YC-1 and performed preliminary in vitro cell uptake study. [$^{18}F$]DFYC showed a significant accumulation in SKBR-3 cells among other cancer cells, proving as a good lead to develop a hypoxic solid tumor such as breast cancer.

• BMB Reports
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• v.48 no.6
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• pp.301-302
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• 2015

Hypoxia is associated with many pathological conditions as well as the normal physiology of metazoans. We identified a lactate-dependent signaling pathway in hypoxia, mediated by the oxygen- and lactate-regulated protein NDRG family member 3 (NDRG3). Oxygen negatively regulates NDRG3 expression at the protein level via the PHD2/VHL system, whereas lactate, produced in excess under prolonged hypoxia, blocks its proteasomal degradation by binding to NDRG3. We also found that the stabilized NDRG3 protein promotes angiogenesis and cell growth under hypoxia by activating the Raf-ERK pathway. Inhibiting cellular lactate production abolishes NDRG3-mediated hypoxia responses. The NDRG3-Raf-ERK axis therefore provides the genetic basis for lactate-induced hypoxia signaling, which can be exploited for the development of therapies targeting hypoxia-induced diseases in addition to advancing our understanding of the normal physiology of hypoxia responses. [BMB Reports 2015; 48(6): 301-302]

• BMB Reports
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• v.53 no.4
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• pp.206-211
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• 2020

Vascular smooth muscle cells (VSMCs) are a unique cell type that has unusual plasticity controlled by environmental stimuli. As an abnormal increase of VSMC proliferation is associated with various vascular diseases, tight regulation of VSMC phenotypes is essential for maintaining vascular homeostasis. Hypoxia is one environmental stress that stimulates VSMC proliferation. Emerging evidence has indicated that microRNAs (miRNAs) are critical regulators in the hypoxic responses of VSMCs. Therefore, we previously investigated miRNAs modulated by hypoxia in VSMCs and found that miR-1260b is one of the most upregulated miRNAs under hypoxia. However, the mechanism that underlies the regulation of VSMCs via miR-1260b in response to hypoxia has not been explored. Here we demonstrated that hypoxia-induced miR-1260b promotes VSMC proliferation. We also identified growth differentiation factor 11 (GDF11), a member of the TGF-β superfamily, as a novel target of miR-1260b. miR-1260b directly targets the 3'UTR of GDF11. Downregulation of GDF11 inhibited Smad signaling and consequently enhanced the proliferation of VSMCs. Our findings suggest that miR-1260b-mediated GDF11-Smad-dependent signaling is an essential regulatory mechanism in the proliferation of VSMCs, and this axis is modulated by hypoxia to promote abnormal VSMC proliferation. Therefore, our study unveils a novel function of miR-1260b in the pathological proliferation of VSMCs under hypoxia.