Yu-Kyoung Park

Differential down-regulation of COX-2 and MMP-13 in human skin fibroblasts by glucosamine-hydrochloride

BACKGROUND Evidence suggests anti-inflammatory effects of glucosamine (GS) on inflammatory diseases. COX-2 is an enzyme to produce prostaglandins. MMPs are the family of matrix metalloproteinases degradable of ECM. Excess expression of COX-2 or MMPs involves in skin inflammation. OBJECTIVE We evaluated whether GS-HCl modulates expression of COX-2 and/or MMPs by IL-1beta or PMA in human skin fibroblasts (HSF) or keratinocytes (HaCaT). METHODS HSF or HaCaT cells were exposed to IL-1beta or PMA without or with GS-HCl. COX-2 or MMPs protein and mRNA expression, respectively, were analyzed by Western blot and RT-PCR. MTS assay was utilized to assess the cytotoxicity of GS-HCl on HSF cells. RESULTS In HSF cells, IL-1beta treatment induced COX-2 and MMP-13 expressions in association with activation of ERKs, p38 MAPK, JNKs, and NF-kappaB. PMA treatment also induced COX-2 and MMP-13 expressions in association with p38 MAPK activation. Of interest, treatment with GS-HCl (10mM) led to blockage of p38 MAPK activation, accumulation of 66kDa COX-2 protein variant (without affecting COX-2 mRNA expression), and transcriptional down-regulation of MMP-13 in the IL-1beta- or PMA-treated HSF cells. Distinctly, pharmacological inhibition of p38 MAPK with SB203580 was associated with transcriptional down-regulation of COX-2 and MMP-13 in the IL-1beta- or PMA-treated HSF cells. In addition, the GS-HCl-mediated COX-2 protein modification was observed in both endogenous and PMA-induced COX-2 in HaCaT cells. CONCLUSIONS GS-HCl differentially down-regulates COX-2 and MMP-13 expression in the IL-1beta- or PMA-treated human skin fibroblasts via the p38 MAPK-independent COX-2 translational inhibition and the p38 MAPK-dependent MMP-13 transcriptional suppression, respectively.

Anti-cancer properties of glucosamine-hydrochloride in YD-8 human oral cancer cells: Induction of the caspase-dependent apoptosis and down-regulation of HIF-1α.

Evidence suggests anti-tumor activities of glucosamine-hydrochloride (GS-HCl). In the present study, we investigated anti-proliferative, growth suppressive and/or pro-apoptotic effects of GS-HCl on YD-8 human oral squamous cell carcinoma (OSCC) cells. Fundamentally, treatment with GS-HCl strongly inhibited proliferation and induced apoptosis in YD-8 cells, as determined by MTS and DNA fragmentation analyses. Of further note, as measured by Western analyses, GS-HCl treatment led to activation of caspase-3, cytosolic accumulation of cytochrome c, down-regulation of Mcl-1 and HIF-1α, up-regulation of GRP78, an indicator of ER stress, and generation of ROS in YD-8 cells. Importantly, results of pharmacological inhibition studies showed that treatment with z-VAD-fmk, a pan-caspase inhibitor, but not with vitamin E, an anti-oxidant strongly blocked the GS-HCl-induced apoptosis in YD-8 cells. Analyses of additional cell culture works further revealed that GS-HCl had a strong growth suppressive effect on not only YD-8 but also YD-10B and YD-38, two other human OSCC cell lines. These findings collectively demonstrate that GS-HCl has anti-proliferative, anti-survival, and pro-apoptotic effects on YD-8 cells and the effects appear to be mediated via mechanisms associated with the mitochondrial-dependent activation of caspases, down-regulation of Mcl-1, and induction of ER stress. Considering HIF-1α as a tumor angiogenic transcription factor, the ability of GS-HCl to down-regulate HIF-1α in YD-8 cells may further support its anti-cancer property. It is thus suggested that GS-HCl may be used as a potential anti-cancer drug against human OSCC.

Pinus densiflora leaf essential oil induces apoptosis via ROS generation and activation of caspases in YD-8 human oral cancer cells

The leaf of Pinus (P.) densiflora, a pine tree widely distributed in Asian countries, has been used as a traditional medicine. In the present study, we investigated the anticancer activity of essential oil, extracted by steam distillation, from the leaf of P. densiflora in YD-8 human oral squamous cell carcinoma (OSCC) cells. Treatment of YD-8 cells with P. densiflora leaf essential oil (PLEO) at 60 μg/ml for 8 h strongly inhibited proliferation and survival and induced apoptosis. Notably, treatment with PLEO led to generation of ROS, activation of caspase-9, PARP cleavage, down-regulation of Bcl-2, and phosphorylation of ERK-1/2 and JNK-1/2 in YD-8 cells. Treatment with PLEO, however, did not affect the expression of Bax, XIAP and GRP78. Importantly, pharmacological inhibition studies demonstrated that treatment with vitamin E (an anti-oxidant) or z-VAD-fmk (a pan-caspase inhibitor), but not with PD98059 (an ERK-1/2 inhibitor) or SP600125 (a JNK-1/2 inhibitor), strongly suppressed PLEO-induced apoptosis in YD-8 cells and reduction of their survival. Vitamin E treatment further blocked activation of caspase-9 and Bcl-2 down-regulation induced by PLEO. Thus, these results demonstrate firstly that PLEO has anti-proliferative, anti-survival and pro-apoptotic effects on YD-8 cells and the effects are largely due to the ROS-dependent activation of caspases.

Transcriptional and translational regulation of COX-2 expression by cadmium in C6 glioma cells

High exposure to cadmium is a risk factor for many neuronal diseases. Overexpression of cyclooxygenase (COX)-2 is linked to many neuroinflammatory and neoplastic diseases. We, herein, investigated the effect of cadmium on the expression of COX-2 in C6 rat glioma cells. Treatment with cadmium sulfate (cadmium) increased the expression of COX-2 mRNA. Remarkably, cadmium treatment further increased expression of not only the N-glycosylated COX-2 protein of 72 kDa but also the unglycosylated COX-2 of 66 kDa, as assessed by the unglycosylated COX-2 induced by tunicamycin or glucosamine, known inhibitors of COX-2 N-glycosylation. Of note, when translation was blocked in the presence of cycloheximide (CHX), levels of both N-glycosylated and unglycosylated COX-2 proteins induced by cadmium rapidly declined but the decline was prevented by MG132, a 26S proteasomal inhibitor. However, in the absence of CHX, cadmium induced and maintained expression of the unglycosylated COX-2 proteins. Pharmacological inhibition studies importantly demonstrated that the cadmium-mediated COX-2 transcriptional upregulation in C6 cells was not shown by exogenous glutathione (GSH) supplementation or treatment with inhibitors of extracellular signal-regulated protein kinase-1/2 (ERK-1/2), p38 MAPK and c-Jun N-terminal protein kinase-1/2 (JNK-1/2), respectively. Expression of COX-2 was not noted in C6 cells exposed to other heavy metals (cobalt or manganese). These results demonstrate that cadmium specifically induces expression of COX-2 through both transcriptional and co-translational (N-glycosylation) regulation in C6 cells in which the cadmium-induced COX-2 transcriptional upregulation is closely related to oxidative stress-dependent activation of the family of MAPKs and the cadmium-induced expression of both N-glycosylated and unglycosylated COX-2 proteins is proteasome- and translation-dependent.

UVB-induced anti-survival and pro-apoptotic effects on HaCaT human keratinocytes via caspase- and PKC-dependent downregulation of PKB, HIAP-1, Mcl-1, XIAP and ER stress

Evidence suggests that solar ultraviolet B (UVB) radiation inhibits growth and/or induces apoptosis of human skin cells. However, mechanisms underlying the UVB-induced anti-survival and pro-apoptotic effects on human skin cells remain unclear. In this study, we investigated the effect of UVB radiation on survival and apoptosis of HaCaT human keratinocytes and determined possible molecular, cellular and signaling mechanisms including cross-regulation, which are responsible for the UVBs anti-survival and/or pro-apoptotic effects. The results showed that UVB radiation at 400 mJ/cm² for 8 h largely decreased cell survival and induced DNA fragmentation, an index of apoptosis, in HaCaT human keratinocytes. On a mechanistic level, UVB radiation triggered the activation of caspase-9, cleavage of poly(ADP-ribose) polymerase, and downregulation of myeloid cell leukemia-1 (Mcl-1), human inhibitor of apoptosis protein-1 (HIAP-1), X-linked IAP (XIAP), and protein kinase B (PKB), but did not affect the expression of B-cell lymphoma-2 in HaCaT cells. UVB radiation also upregulated the expression of glucose-regulated protein 78 (GRP78), an endoplasmic reticulum (ER) stress marker, in HaCaT cells. Of note, results of pharmacological inhibition studies have demonstrated that pretreatment with z-VAD-fmk, a pan-caspase inhibitor strongly attenuated UVB-induced apoptosis, the activation of caspase-9, downregulation of Mcl-1, XIAP and PKB (but not HIAP-1), and upregulation of GRP78, while pretreatment with GF109203 or GO6983, pan-PKC inhibitors, substantially blocked the UVB-induced reduction of cell survival, activation of caspase-9, downregulation of HIAP-1, XIAP, and PKB (but not Mcl-1), and GRP78 upregulation in HaCaT cells. Collectively, these results demonstrated that UVB has strong anti-survival and pro-apoptotic effects on HaCaT cells and the effects were largely mediated via the activation of caspase-9 and protein kinase Cs, which subsequently downregulated PKB, XIAP, HIAP-1 and Mcl-1, and triggered ER stress.

Overexpression of cyclooxygenase‐2 in NCI‐H292 human alveolar epithelial carcinoma cells: Roles of p38 MAPK, ERK‐1/2, and PI3K/PKB signaling proteins

Evidence suggests overexpression of COX‐2 and its role in many human cancers, including lung. However, the regulatory mechanism underlying COX‐2 overexpression in lung cancer is not fully understood. We herein investigated whether COX‐2 is overexpressed in human airway cancer cell lines, including A549 (lung), Hep‐2 (bronchial), and NCI‐H292 (alveolar). When grown in cell culture medium containing 10% FBS (serum), of note, there was strong and transient induction of COX‐2 protein and mRNA in NCI‐H292 cells, but little or low COX‐2 expression is seen in A549 or Hep‐2 cells. Interestingly, strong and sustained activities of ERK‐1/2, JNK‐1/2, p38 MAPK, and PKB were also shown in NCI‐H292 cells grown in presence of serum. Profoundly, results of pharmacological inhibition studies demonstrated that the serum‐dependent COX‐2 up‐regulation in NCI‐H292 cells is attributed to not only the p38 MAPK‐, PI3K/PKB‐, and ERK‐1/2‐mediated COX‐2 transcriptional up‐regulation but also the p38 MAPK‐ and ERK‐1/2‐mediated post‐transcriptional COX‐2 mRNA stabilization. Of further note, it was shown that the ERK‐1/2 and PI3K/PKB (but not COX‐2, p38 MAPK, and JNK‐1/2) activities are necessary for growth of NCI‐H292 cells. These findings collectively demonstrate for the first time that COX‐2 expression is transiently up‐regulated by serum addition in NCI‐H292 cells and the serum‐induced COX‐2 expression is closely linked to the p38 MAPK‐, ERK‐1/2‐, and PI3K/PKB‐mediated COX‐2 transcriptional and post‐transcriptional up‐regulation. J. Cell. Biochem. 112: 3015–3024, 2011.

Identification of KMU-3, a novel derivative of gallic acid, as an inhibitor of adipogenesis.

Differentiation of preadipocyte, also called adipogenesis, leads to the phenotype of mature adipocyte. Excessive adipogenesis, however, is largely linked to the development of obesity. Herein we investigated a library of 53 novel chemicals, generated from a number of polyphenolic natural compounds, on adipogenesis. Strikingly, among the chemicals tested, KMU-3, a derivative of gallic acid, strongly suppressed lipid accumulation during the differentiation of 3T3-L1 preadipocytes into adipocytes. On mechanistic levels, KMU-3 inhibited expressions of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), and fatty acid synthase (FAS) during adipocyte differentiation. Moreover, KMU-3 reduced expressions of adipokines, including retinol binding protein-4 (RBP-4), leptin, and regulated on activation, normal T cell expressed and secreted (RANTES) during adipocyte differentiation. Of further note, KMU-3 rapidly blocked the phosphorylation of signal transducer and activator of transcription-3 (STAT-3) during the early stage of adipogenesis. Importantly, pharmacological inhibition studies revealed that AG490, a JAK-2/STAT-3 inhibitor suppressed adipogenesis and STAT-3 phosphorylation, implying that early blockage of STAT-3 activity is crucial for the KMU-3-mediated anti-adipogenesis. These findings demonstrate firstly that KMU-3 inhibits adipogenesis by down-regulating STAT-3, PPAR-γ, C/EBP-α, and FAS. This work shows that KMU-3 is an inhibitor of adipogenesis and thus may have therapeutic potential against obesity.

Short-term treatment with glucosamine hydrochloride specifically downregulates hypoxia-inducible factor-1α at the protein level in YD-8 human tongue cancer cells

Hypoxia-inducible factor-1 (HIF-1) is a tumor angiogenic transcription factor composed of an α and β subunit. We investigated the effect of glucosamine hydrochloride (GS-HCl) on the expression of HIF-1α and HIF-1β in serum‑treated YD-8 human tongue cancer cells. While long-term (24 h) treatment with GS-HCl strongly repressed the expression of HIF-1α and HIF-1β at both the protein and mRNA levels, short-term (4 h) GS-HCl treatment inhibited HIF-1α at the protein level. Short-term GS-HCl treatment also decreased phosphorylation of p70S6K and S6, translation-related proteins. However, the results of subsequent pharmacological inhibition and protein stability analyses indicated that HIF-1α protein downregulation induced by short-term GS-HCl treatment was not through modulation of the mTOR/p70S6K/S6 signaling pathways, the 26S proteasomal and lysosomal activities and HIF-1α protein stability. Importantly, our further analyses identified that HIF-1α protein downregulation induced by short-term GS-HCl treatment was blunted by exogenous administration of the citric acid cycle metabolites citrate and 2-oxoglutarate, but not the glycolytic end byproducts pyruvate and lactate. These findings demonstrate firstly that short-term GS treatment selectively downregulates HIF-1α at the protein level in YD-8 cells via interference of production of the citric acid cycle metabolites. It is proposed that short-term GS-HCl exposure may be applied for the treatment of oral tumors with high expression of HIF-1α.

BAI, a 3-aminoindazole derivative, inhibits interleukin-1β-induced expression of cyclooxygenase-2 in A549 human airway cells

Cyclooxygenase (COX)-2 and its products, including PGE2, are key inflammatory mediators. In this study, we have assessed the pharmacological characteristics of BAI, a 3-aminoindazole derivative and a novel cyclin-dependent kinase (CDK) inhibitor, for regulation of COX-2 expression induced by interleukin (IL)-1β in A549 human airway cells. Treatment with BAI strongly inhibited IL-1β-induced expression of COX-2 at both the protein and mRNA levels. Results of luciferase experiments also revealed that BAI treatment reduced IL-1β-induced COX-2 promoter activity. Distinctly, treatment with BAI did not affect IL-1β-induced phospho-rylation of extracellular signal-regulated protein kinase-1/2 (ERK-1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal protein kinase-1/2 (JNK-1/2) and proteolysis of IκB-α, an inhibitor of nuclear factor (NF)-κB, but inhibited IL-1β-induced phosphorylation of histone H1, a target for phosphorylation by CDKs. siRNA transfection experiments demonstrated that knockdown of CDK2 and CDK4 led to a slight reduction of IL-1β-induced histone H1 phosphorylation but had no effect on IL-1β-induced COX-2 expression. Interestingly, additional cell culture experiments showed the ability of BAI to repress the PMA-induced COX-2 expression in A549 cells and serum-dependent COX-2 expression in NCI-H292 cells, a human laryngeal cell line. Collectively, these results demonstrate firstly that BAI downregulates IL-1β-induced COX-2 expression through transcriptional repression, which appears to be independent of CDK2, CDK4, MAPKs and NF-κB, in A549 cells. It is suggested that BAI may be a potential candidate for treatment of the airway inflammatory diseases where COX-2 overexpression is problematic.

Anti-Adipogenic Effects on 3T3-L1 Cells and Zebrafish by Tanshinone IIA

Tanshinone IIA is a diterpene quinone isolated from the roots of Salvia miltiorrhiza bunge that has traditionally been used in China for the treatment of cardiovascular and cerebrovascular disorders. Although there is recent evidence showing that tanshinone IIA has an anti-obesity effect, its underlying mechanism of anti-obesity effect is poorly understood. Here, we investigated the effect of tanshinone IIA on lipid accumulation in 3T3-L1 preadipocytes and zebrafish. Notably, tanshinone IIA at 10 μM concentration greatly reduced lipid accumulation and triglyceride (TG) contents during 3T3-L1 preadipocyte differentiation, suggesting its anti-adipogenic effect. On mechanistic levels, tanshinone IIA reduced the expression levels of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A but also the phosphorylation levels of signal transducer and activator of transcription-3/5 (STAT-3/5) in differentiating 3T3-L1 cells. In addition, tanshinone IIA strongly inhibited leptin and resistin mRNA expression in differentiating 3T3-L1 cells. Importantly, the tanshinone IIA’s lipid-reducing effect was also seen in zebrafish. In sum, these findings demonstrate that tanshinone IIA has anti-adipogenic effects on 3T3-L1 cells and zebrafish, and its anti-adipogenic effect on 3T3-L1 cells is largely attributable to the reduced expression and/or phosphorylation levels of C/EBP-α, PPAR-γ, FAS, perilipin A, and STAT-3/5.