• Journal of Ginseng Research
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• 제43권3호
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• pp.421-430
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• 2019

Background: The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell-like features through regulation of self-renewal activity. Methods: The effects of RGE and Rg3 on the proportion of $CD44^{high}/CD24^{low}$ cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres were verified by immunoblot analysis. Results: Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of $CD44^{high}/CD24^{low}$ in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell-like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling. Conclusion: This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

• Radiation Oncology Journal
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• 제34권3호
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• pp.230-238
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• 2016

Purpose: Hypoxia can impair the therapeutic efficacy of radiotherapy (RT). Therefore, a new strategy is necessary for enhancing the response to RT. In this study, we investigated whether the combination of nanoparticles and RT is effective in eliminating the radioresistance of hypoxic tumors. Materials and Methods: Gold nanoparticles (GNPs) consisting of a silica core with a gold shell were used. CT26 colon cancer mouse model was developed to study whether the combination of RT and GNPs reduced hypoxia-induced radioresistance. Hypoxia inducible $factor-1{\alpha}$ ($HIF-1{\alpha}$) was used as a hypoxia marker. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were conducted to evaluate cell death. Results: Hypoxic tumor cells had an impaired response to RT. GNPs combined with RT enhanced anti-tumor effect in hypoxic tumor compared with RT alone. The combination of GNPs and RT decreased tumor cell viability compare to RT alone in vitro. Under hypoxia, tumors treated with GNPs + RT showed a higher response than that shown by tumors treated with RT alone. When a reactive oxygen species (ROS) scavenger was added, the enhanced antitumor effect of GNPs + RT was diminished. Conclusion: In the present study, hypoxic tumors treated with GNPs + RT showed favorable responses, which might be attributable to the ROS production induced by GNPs + RT. Taken together, GNPs combined with RT seems to be potential modality for enhancing the response to RT in hypoxic tumors.

• BMB Reports
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• 제56권4호
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• pp.252-257
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• 2023

The hypoxia-inducible factor-1α (HIF-1α) is a key regulator of hypoxic stress under physiological and pathological conditions. HIF-1α protein stability is tightly regulated by the ubiquitin-proteasome system (UPS) and autophagy in normoxia, hypoxia, and the tumor environment to mediate the hypoxic response. However, the mechanisms of how the UPS and autophagy interplay for HIF-1α proteostasis remain unclear. Here, we found a HIF-1α species propionylated at lysine (K) 709 by p300/CREB binding protein (CBP). HIF-1α stability and the choice of degradation pathway were affected by HIF-1α propionylation. K709-propionylation prevented HIF-1α from degradation through the UPS, while activated chaperon-mediated autophagy (CMA) induced the degradation of propionylated and nonpropionylated HIF-1α. CMA contributed to HIF-1α degradation in both normoxia and hypoxia. Furthermore, the pan-cancer analysis showed that CMA had a significant positive correlation with the hypoxic signatures, whereas SIRT1, responsible for K709-depropionylation correlated negatively with them. Altogether, our results revealed a novel mechanism of HIF-1α distribution into two different degradation pathways.

• Journal of Ginseng Research
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• 제45권5호
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• pp.610-616
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• 2021

Background: Thymic stromal lymphopoietin (TSLP) acts as a master switch for inflammatory responses. Ginsenoside Rg3 (Rg3) which is an active ingredient of Panax ginseng Meyer (Araliaceae) is known to possess various therapeutic effects. However, a modulatory effect of Rg3 on TSLP expression in the inflammatory responses remains poorly understood. Methods: We investigated antiinflammatory effects of Rg3 on an in vitro model using HMC-1 cells stimulated by PMA plus calcium ionophore (PMACI), as well as an in vivo model using PMA-induced mouse ear edema. TSLP and vascular endothelial growth factor (VEGF) levels were detected using enzyme-linked immunosorbent assay or real-time PCR analysis. Murine double minute 2 (MDM2) and hypoxia-inducible factor 1α (HIF1α) expression levels were detected using Western blot analysis. Results: Rg3 treatment restrained the production and mRNA expression levels of TSLP and VEGF in activated HMC-1 cells. Rg3 down-regulated the MDM2 expression level increased by PMACI stimulation. The HIF1α expression level was also reduced by Rg3 in activated HMC-1 cells. In addition, Rg3-administered mice showed the decreased redness and ear thickness in PMA-irritated ear edema. Rg3 inhibited the TSLP and VEGF levels in the serum and ear tissue homogenate. Moreover, the MDM2 and HIF1α expression levels in the ear tissue homogenate were suppressed by Rg3. Conclusion: Taken together, the current study identifies new mechanistic evidence about MDM2/HIF1α pathway in the antiinflammatory effect of Rg3, providing a new effective therapeutic strategy for the treatment of skin inflammatory diseases.

• Molecules and Cells
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• 제37권2호
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• pp.178-186
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• 2014

Differential transcription of the clusterin (CLU) gene yields two CLU isoforms, a nuclear form (nCLU) and a secretory form (sCLU), which play crucial roles in prostate tumorigenesis. Pro-apoptotic nCLU and anti-apoptotic sCLU have opposite effects and are differentially expressed in normal and cancer cells; however, their regulatory mechanisms at the transcriptional level are not yet known. Here, we examined the transcriptional regulation of nCLU in response to hypoxia. We identified three putative hypoxia response elements (HREs) in the human CLU promoter between positions -806 and +51 bp. Using a luciferase reporter, electrophoretic gel mobility shift, and chromatin immunoprecipitation assays, we further showed that hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$) bound directly to these sites and activated transcription. Exposure to the hypoxia-mimetic compound $CoCl_2$, incubation under 1% $O_2$ conditions, or overexpression of HIF-$1{\alpha}$ enhanced nCLU expression and induced apoptosis in human prostate cancer PC3M cells. However, LNCaP prostate cancer cells were resistant to hypoxia-induced cell death. Methylation-specific PCR analysis revealed that the CLU promoter in PC3M cells was not methylated; in contrast, the CLU promoter in LNCap cells was methylated. Co-treatment of LNCaP cells with $CoCl_2$ and a demethylating agent promoted apoptotic cell death through the induction of nCLU. We conclude that nCLU expression is regulated by direct binding of HIF-$1{\alpha}$ to HRE sites and is epigenetically controlled by methylation of its promoter region.

• Journal of Ginseng Research
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• 제46권3호
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• pp.408-417
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• 2022

Background: Korean Red Ginseng extract (KRGE) has been used as a health supplement and herbal medicine. Astrocytes are one of the key cells in the central nervous system (CNS) and have bioenergetic potential as they stimulate mitochondrial biogenesis. They play a critical role in connecting the brain vasculature and nerves in the CNS. Methods: Brain samples from KRGE-administered mice were tested using immunohistochemistry. Treatment of human brain astrocytes with KRGE was subjected to assays such as proliferation, cytotoxicity, Mitotracker, ATP production, and O₂ consumption rate as well as western blotting to demonstrate the expression of proteins related to mitochondria functions. The expression of hypoxia-inducible factor-1α (HIF-1α) was diminished utilizing siRNA transfection. Results: Brain samples from KRGE-administered mice harbored an increased number of GFAP-expressing astrocytes. KRGE triggered the proliferation of astrocytes in vitro. Enhanced mitochondrial biogenesis induced by KRGE was detected using Mitotracker staining, ATP production, and O₂ consumption rate assays. The expression of proteins related to mitochondrial electron transport was increased in KRGE-treated astrocytes. These effects were blocked by HIF-1α knockdown. The factors secreted from KRGE-treated astrocytes were determined, revealing the expression of various cytokines and growth factors, especially those related to angiogenesis and neurogenesis. KRGE-treated astrocyte conditioned media enhanced the differentiation of adult neural stem cells into mature neurons, increasing the migration of endothelial cells, and these effects were reduced in the background of HIF-1α knockdown. Conclusion: Our findings suggest that KRGE exhibits prophylactic potential by stimulating astrocyte mitochondrial biogenesis through HIF-1α, resulting in improved neurovascular function.

• Molecules and Cells
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• 제28권6호
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• pp.537-543
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• 2009

Keratinocyte overgrowth after UVB exposure is believed to contribute to skin photoageing and cancer development. However, little is known about the transcription factors that epigenetically regulate keratinocyte response to UVB. Recently, $HIF-1{\alpha}$ was found to play a role in epidermal homeostasis by controlling the keratinocyte cell cycle, and thus, we hypothesized that $HIF-1{\alpha}$ is involved in UVB-induced keratinocyte growth. In cultured keratinocytes, $HIF-1{\alpha}$ was found to be down-regulated shortly after UVB exposure and to be involved in UVB-induced proliferation. In mice repeatedly treated with UVB, the epidermis became hyperplasic and keratinocytes lacked $HIF-1{\alpha}$ in nuclei. Based on these results, we suggest that the deregulation of $HIF-1{\alpha}$ is associated with UVB-induced hyperplasia of the epidermis. This work provides insight of the molecular mechanism underlying UV-induced photoageing and skin cancer development.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5363-5369
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• 2012

High-risk human papillomavirus (HPV) especially HPV-16 and HPV-18 types are speculated to be important risk factors in non-smoking associated lung cancer in Asia. Increasing evidence has demonstrated that HPV oncoproteins may contribute to lung tumorigenesis and cell transformation. Importantly, HPV 16/18 E6 and E7 oncoproteins can mediate expression of multiple target genes and proteins, such as p53/pRb, VEGF, HIF-$1{\alpha}$, cIAP-2, and hTERT, and contribute to cell proliferation, angiogenesis and cell immortalization through different signaling pathways in lung cancer. This article provides an overview of experiment data on HPV-associated lung cancer, describes the main targets on which HPV E6/E7 oncoproteins act, and further discusses the potential signaling pathways in which HPV E6/E7 oncoproteins are involved. In addition, we also raise questions regarding existing problems with the study of HPV-associated lung cancer.

• Tuberculosis and Respiratory Diseases
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• 제66권3호
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• pp.178-185
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• 2009

연구배경: 암세포는 빠른 증식 속도로 인하여 상대적인 저산소증에 노출되면서 비정상적인 종양 혈관을 형성하여 치명적인 병인을 형성한다. EGCG는 녹차의 추출물로 간세포암주 및 전립선암주에서 HIF-1$\alpha$의 발현을 억제하는 것으로 알려져 있다. 그러나 EGCG의 비혈관 증식성 효과에 대해서는 아직 정확히 규명되어 있지 않다. 본 연구에서는 EGCG가 비소세포폐암주에서 HIF-1$\alpha$ 및 VEGF의 발현에 대한 억제 가능성을 확인하여 보고자 하였다. 방 법: 비소세포폐암주인 A549를 RPMI배지에서 계대 배양하였다. 저산소 유사 상태는 Modular Incubator Chamber (MIC-101)을 이용하였고 5% 이산화탄소와 95% 질소 혼합 가스를 5분 동안 공급하여 저산소 상태를 만들었으며 세포 배양액을 채취하여 혈액가스분석기(Blood Gas Analyzer ABL725)로 세포 배양 상태를 측정하였다. 세포의 증식 상태는 MTT 방법을 실시하였다. EGCG는 0, 12.5, 25, 50,100 ${\mu}mol/L$로 농도 변화를 주어 실험을 시행하였으며 16시간 동안 저산소 상태를 만든 뒤 HIF-1$\alpha$, VEGF, $\beta$-actin mRNA에 대해 Real time PCR을 시행하였다. 결 과: 48시간과 72시간에서 저산소 상태에 놓인 A549 세포의 증식능력은 대조군에 비하여 억제되었다. EGCG 는 저산소화에 의해 유도된 HIF-1$\alpha$의 mRNA의 전사를 유의하게 억제하였다. 그러나 이러한 억제 효과는 VRGF mRNA 발현에는 미치지 못하였다. 결 론: EGCG는 HIF-1$\alpha$의 발현을 억제함으로써 비소세포암주에서의 예방적 항암요법이나 항암 치료요법 시의 주요 작용 목표로 사용될 수 있을 것으로 보인다.

• BMB Reports
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• 제56권3호
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• pp.196-201
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• 2023

Renal fibrosis is the final manifestation of chronic kidney disease (CKD) regardless of etiology. Hypoxia-inducible factor-2 alpha (HIF-2α) is an important regulator of chronic hypoxia, and the late-stage renal tubular HIF-2α activation exerts protective effects against renal fibrosis. However, its specific role in progressive renal fibrosis remains unclear. Here, we investigated the effects of the long-term tubular activation of HIF-2α on renal function and fibrosis, using in vivo and in vitro models of renal fibrosis. Progressive renal fibrosis was induced in renal tubular epithelial cells (TECs) of tetracycline-controlled HIF-2α transgenic (Tg) mice and wild-type (WT) controls through a 6-week adenine diet. Tg mice were maintained on doxycycline (DOX) for the diet period to induce Tg HIF-2α expression. Primary TECs isolated from Tg mice were treated with DOX (5 ㎍/ml), transforming growth factor-β1 (TGF-β1) (10 ng/ml), and a combination of both for 24, 48, and 72 hr. Blood was collected to analyze creatinine (Cr) and blood urea nitrogen (BUN) levels. Pathological changes in the kidney tissues were observed using hematoxylin and eosin, Masson's trichrome, and Sirius Red staining. Meanwhile, the expression of fibronectin, E-cadherin and α-smooth muscle actin (α-SMA) and the phosphorylation of p38 mitogen-activated protein kinase (MAPK) was observed using western blotting. Our data showed that serum Cr and BUN levels were significantly lower in Tg mice than in WT mice following the adenine diet. Moreover, the protein levels of fibronectin and E-cadherin and the phosphorylation of p38 MAPK were markedly reduced in the kidneys of adenine-fed Tg mice. These results were accompanied by attenuated fibrosis in Tg mice following adenine administration. Consistent with these findings, HIF-2α overexpression significantly decreased the expression of fibronectin in TECs, whereas an increase in α-SMA protein levels was observed after TGF-β1 stimulation for 72 hr. Taken together, these results indicate that long-term HIF-2α activation in CKD may inhibit the progression of renal fibrosis and improve renal function, suggesting that long-term renal HIF-2α activation may be used as a novel therapeutic strategy for the treatment of CKD.