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ABSTRACT: Inflammatory conditions elicited by extrinsic environmental factors promote malignant transformation, tumor growth, and metastasis. Although the role of T cells in cancer promotion has been examined, little is known about the underlying molecular mechanisms of interleukin-17 A (IL-17A), a proinflammatory cytokine produced by activated CD4(+) memory T cells, in carcinogenesis. Here, we report that IL-17A induces neoplastic transformation of JB6 Cl41 cells through activation of Tumor progression locus 2 (TPL2). IL-17A dose- and time-dependently increases TPL2 phosphorylation in JB6 Cl41 cells through IL-17A receptor. IL-17A activates MEKs-ERKs, JNKs-c-Jun, and STAT3 signaling pathways, which are inhibited by a TPL2 kinase inhibitor (TKI). Furthermore, IL-17A activates c-fos and c-jun promoter activity, resulting in increased activator protein-1 (AP-1) activity. When small interfering RNA (siRNA) of IL-17A receptor (IL-17R), IL-17A, and TPL2 were introduced into JB6 Cl41 cells, respectively, IL-17A-induced AP-1 activity was significantly decreased compared to control cells. Similarly, TPL2 inhibition suppressed AP-1 activity induced by IL-17A. The knockdown of IL-17R and TKI treatment in JB6 Cl41 cells resulted in decreased IL-17A-induced cell transformation. The in vivo chorioallantoic membrane (CAM) assay also showed that IL-17A increased tumor formation of JB6 Cl41 cells, whereas TKI inhibited the tumorigenesis promoted by IL-17A. Consistent with these observations, knockdown of IL-17A and/or inhibition of TPL2 attenuated tumorigenecity of human breast cancer MCF7 cells. Together, our findings point to a critical role for the IL-17A-induced TPL2 signaling pathway in supporting cancer-associated inflammation in the tumor microenvironment. Therapeutic approaches that target this pathway may therefore effectively inhibit carcinogenesis.
Carcinogenesis 11/2012; · 5.70 Impact Factor
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ABSTRACT: Tamoxifen (TAM) resistance is a serious clinical problem in the treatment of breast cancer. Here, we found that S-adenosylmethionine (SAM) and DNA methyltransferase1 (DNMT1) expression are up-regulated in TAM-resistant breast cancer (TAMR-MCF-7) cells. We further focused on whether increased SAM with DNMT1 overexpression in TAMR-MCF-7 cells lead to aberrant methylation of the PTEN gene promoter and its therapeutic potential. Methylation-specific PCR analyses revealed that two sites within the PTEN promoters were methylated in TAMR-MCF-7 cells, which resulted in down-regulation of PTEN expression and increase in Akt phosphorylation. Both the loss of PTEN expression and the increased Akt phosphorylation in TAMR-MCF-7 cells were completely reversed by 5-aza-2'-deoxycytidine (5-Aza), a DNMT inhibitor. 5-Aza inhibited the basal cell proliferation rate of TAMR-MCF-7 cells and intraperitoneal injection of 5-Aza significantly suppressed TAMR-MCF-7 tumor growth in a xenograft study. Immunohistochemistry showed that PTEN expression in TAM-resistant human breast cancer tissues was lower than in TAM-responsive cases. These results suggest that methylation of the PTEN promoter related to both SAM increase and DNMT1 activation contributes to persistent Akt activation and are potential therapeutic targets for reversing TAM resistance in breast cancer.
Breast Cancer Research and Treatment 11/2011; 130(1):73-83. · 4.43 Impact Factor
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ABSTRACT: Ultraviolet A (UVA) radiation (λ = 320-400 nm) is considered a major cause of human skin cancer. Pin1, a peptidyl prolyl isomerase, is overexpressed in most types of cancer tissues and plays an important role in cell proliferation and transformation. Here, we demonstrated that Pin1 expression was enhanced by low energy UVA (300-900 mJ/cm(2)) irradiation in both skin tissues of hairless mice and JB6 C141 epidermal cells. Exposure of epidermal cells to UVA radiation increased cell proliferation and cyclin D1 expression, and these changes were blocked by Pin1 inhibition. UVA irradiation also increased activator protein-1 (AP-1) minimal reporter activity and nuclear levels of c-Jun, but not c-Fos, in a Pin1-dependent manner. The increases in Pin1 expression and in AP-1 reporter activity in response to UVA were abolished by N-acetylcysteine (NAC) treatment. Finally, we found that pre-exposure of JB6 C141 cells to UVA potentiated EGF-inducible, anchorage-independent growth, and this effect was significantly suppressed by Pin1inhibition or by NAC.
Biochemical and Biophysical Research Communications 06/2011; 410(1):68-74. · 2.48 Impact Factor
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ABSTRACT: Gα(12/13) play a role in oncogenic transformation and tumor growth. Cysteine-rich protein 61 (CYR61) is a growth-factor-inducible angiogenic factor. In view of potential overlapping functions between Gα(12/13) and CYR61, this study investigated the role of these G proteins in CYR61 induction in association with hyperplastic vascular abnormality.
Overexpression of activated Gα(12) or Gα(13) induced CYR61 expression in vascular smooth muscle cells (VSMCs). Gene knockdown and knockout experiments revealed that sphingosine-1-phosphate (S1P) treatment induced CYR61 via Gα(12/13). JunD/activator protein-1 (AP-1) was identified as a transcription factor required for CYR61 transactivation by S1P. Deficiencies in Gα(12/13) abrogated AP-1 activation and AP-1-mediated CYR61 induction. c-Jun N-terminal kinase was responsible for CYR61 induction. Moreover, deficiencies of Gα(12/13) abolished c-Jun N-terminal kinase-dependent CYR61 induction by S1P. N-acetyl-l-cysteine or NADPH oxidase inhibitor treatment reversed CYR61 induction by S1P, indicating that reactive oxygen species are responsible for this process. The levels of Gα(12/13) were increased within thickened intimas and medias in wire-injured mouse femoral arteries, which was accompanied by simultaneous CYR61 induction. Moreover, Gα(12/13) and CYR61 were costained in the arteriosclerotic lesions immediately adjacent to human tumor tissues.
Gα(12/13) regulate AP-1-dependent CYR61 induction in VSMCs and promote VSMC migration, and they are upregulated with CYR61 in arteriosclerotic lesions.
Arteriosclerosis Thrombosis and Vascular Biology 01/2011; 31(4):861-9. · 6.37 Impact Factor
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ABSTRACT: Neointima, defined as abnormal growth of the intimal layer of blood vessels, is believed to be a critical event in the development of vascular occlusive disease. Although resveratrol's inhibitory effects on proliferation and migration of vascular smooth muscle cells has been reported, its activity on neointimal formation is still unclear. Oral administration of trans-resveratrol significantly suppressed intimal hyperplasia in a wire-injured femoral artery mouse model. In cultured vascular smooth muscle cells, trans-resveratrol inhibited platelet-derived growth factor-stimulated DNA synthesis and cell proliferation with down-regulation of cyclin D and pRB. Moreover, platelet-derived growth factor-induced production of reactive oxygen species was inhibited by trans-resveratrol and the compound induced heme oxygenase-1 (HO-1). The anti-proliferative activity of trans-resveratrol was reversed by an HO-1 inhibitor, ZnPPIX. Subcellular fractionation and reporter gene analyses revealed that trans-resveratrol increased the level of nuclear Nrf2 and antioxidant response element reporter activity, and that these were essential for the induction of HO-1. Trans-resveratrol also enhanced the activities of phosphatidyl inositol 3-kinase and extracellular signal regulated kinase, and phosphatidyl inositol 3-kinase was required for Nrf2/antioxidant response element-dependent HO-1 induction. These data have significant implications for the elucidation of the pharmacological mechanism by which trans-resveratrol prevents vascular occlusive diseases.
Molecular Nutrition & Food Research 10/2010; 54(10):1497-505. · 4.30 Impact Factor
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ABSTRACT: Endocrine therapies, which inhibit estrogen receptor signaling, are the most common and effective treatments for estrogen receptoralpha-positive breast cancer. However, the utility of these agents is limited by the frequent development of resistance, and the precise mechanisms underlying endocrine therapy resistance remain incompletely understood. Here, we demonstrate that peptidyl-prolyl isomerase Pin1 is an important determinant of resistance to tamoxifen and show that Pin1 increases E2F-4- and Egr-1-driven expression of LC-3 as a result of an increased interaction with and phosphorylation of MEK1/2. In human tamoxifen-resistant breast cancer, our results show a significant correlation between Pin1 overexpression and high levels of LC-3. Promoter activity as well as expression levels of Pin1 were drastically higher in tamoxifen-resistant MCF7 cells than control MCF7 cells, as were levels of LC-3 mRNA and protein, an autophagy marker. Pin1(-/-) mouse embryonic fibroblasts showed lower 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MEK1/2 phosphorylation than Pin1(+/+) mouse embryonic fibroblasts. Silencing of Pin1 expression inhibited TPA-induced MEK1/2 phosphorylation in MCF7 cells. Moreover, PD98059, a specific inhibitor of MEK1/2, and juglone, a potent Pin1 inhibitor, significantly suppressed the TPA-induced expression of E2F-4 as well as Egr-1 transcription factors, which control LC-3 gene expression. Importantly, 4-hydroxy tamoxifen, when used in combination with silencing of Pin1 or LC-3, increased cleaved poly(ADP-ribose) polymerase and DNA fragmentation to inhibit cologenic growth of MCF7 cells. We therefore link the Pin1-MEK pathway and LC-3-mediated tamoxifen resistance and show the therapeutic potential of Pin1 in the treatment of tamoxifen-resistant breast cancer.
Journal of Biological Chemistry 07/2010; 285(31):23829-41. · 4.77 Impact Factor
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ABSTRACT: Endocrine therapies, which inhibit estrogen receptor signaling, are the most common and effective treatments for estrogen
receptorα-positive breast cancer. However, the utility of these agents is limited by the frequent development of resistance,
and the precise mechanisms underlying endocrine therapy resistance remain incompletely understood. Here, we demonstrate that
peptidyl-prolyl isomerase Pin1 is an important determinant of resistance to tamoxifen and show that Pin1 increases E2F-4-
and Egr-1-driven expression of LC-3 as a result of an increased interaction with and phosphorylation of MEK1/2. In human tamoxifen-resistant breast cancer, our
results show a significant correlation between Pin1 overexpression and high levels of LC-3. Promoter activity as well as expression
levels of Pin1 were drastically higher in tamoxifen-resistant MCF7 cells than control MCF7 cells, as were levels of LC-3 mRNA
and protein, an autophagy marker. Pin1−/− mouse embryonic fibroblasts showed lower 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MEK1/2 phosphorylation than Pin1+/+ mouse embryonic fibroblasts. Silencing of Pin1 expression inhibited TPA-induced MEK1/2 phosphorylation in MCF7 cells. Moreover,
PD98059, a specific inhibitor of MEK1/2, and juglone, a potent Pin1 inhibitor, significantly suppressed the TPA-induced expression
of E2F-4 as well as Egr-1 transcription factors, which control LC-3 gene expression. Importantly, 4-hydroxy tamoxifen, when used in combination with silencing of Pin1 or LC-3, increased cleaved poly(ADP-ribose) polymerase and DNA fragmentation to inhibit cologenic growth of MCF7 cells. We therefore
link the Pin1-MEK pathway and LC-3-mediated tamoxifen resistance and show the therapeutic potential of Pin1 in the treatment
of tamoxifen-resistant breast cancer.
Journal of Biological Chemistry 07/2010; 285(31):23829-23841. · 4.77 Impact Factor
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ABSTRACT: Abnormal proliferation of vascular smooth muscle cells (VSMCs) contributes to intima formation after stenting and balloon angioplasty. Pin1, a peptidyl prolyl isomerase recognizing phosphorylated Ser/Thr-Pro, isomerizes the peptide bond. Because Pin1 overexpression is associated with transformation and the uncontrolled cell growth of tumors, we hypothesized that Pin1 functions as a chronic stimulator of VSMC proliferation. Pin1-positive smooth muscle cells were seen in the neointimal region of the femoral artery after guidewire injury. Exposure of VSMCS to platelet-derived growth factor (PDGF) increased Pin1 expression in a concentration-dependent manner. Basal cell growth rate and cyclin D1 expression were enhanced in Pin1-overexpressing VSMCs (Pin1-VSMCs). Moreover, PDGF-induced production of reactive oxygen species (ROS) in Pin1-VSMCs was higher than in control VSMCs. In Pin1-VSMCs, heme oxygenase-1 (HO-1) induction in response to nitric oxide donor was suppressed compared to control VSMCs. Nuclear translocation of nuclear factor E2-related factor-2 (Nrf2) was also diminished in Pin1-VSMCs. In contrast, the activity of the inducible minimal antioxidant response element (ARE) was potentiated in Pin1-null mouse embryonic fibroblasts (MEFs), compared to Pin1-wild-type MEFs. Moreover, Nrf2 ubiquitination was stimulated by Pin1 overexpression. Intraperitoneal injection of juglone (a Pin1 inhibitor) for 3weeks (1mg/kg, two times a week) significantly suppressed neointimal formation induced by wire injury. In conclusion, Pin1 induction during neointimal formation may be associated with ROS-mediated VSMC proliferation via down-regulation of Nrf2/ARE-dependent HO-1 expression. Pin1 may be a novel therapeutic target for several vascular diseases including atherosclerosis and stenosis.
Free radical biology & medicine 03/2010; 48(12):1644-53. · 5.42 Impact Factor
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ABSTRACT: Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in joints and subsequent destruction of cartilage and bone. Inflammatory mediators such as PGs and proinflammatory cytokines contribute to RA progress. Pin1, a peptidyl prolyl isomerase, plays important pathophysiological roles in several diseases, including cancer and neurodegeneration. We found that both Pin1 and cyclooxygenase-2 (COX-2) were highly expressed in ankle tissues of type II collagen-induced RA mice. HTB-94 cells overexpressing Pin1 and primary cultured human chondrocytes showed increased basal expression of proinflammatory proteins (COX-2, inducible NO synthase, TNF-alpha, and IL-1beta). Site-directed mutagenesis revealed that Pin1-mediated transcriptional activation of COX-2 was coordinately regulated by NF-kappaB, CREB, and C/EBP. Gel shift, reporter gene, and Western blot analyses confirmed that NF-kappaB, CREB, and C/EBP were consistently activated in chondrocytes overexpressing Pin1. Treatment of RA mice with juglone, a chemical inhibitor of Pin1, significantly reduced RA progress and COX-2 expression in the ankle tissues. Moreover, juglone dose dependently decreased the basal COX-2 expression in primary cultured chondrocytes from RA patients. These results demonstrate that Pin1 induction during RA progress stimulates proinflammatory protein expression by activating NF-kappaB, CREB, and C/EBP, and suggest that Pin1 is a potential therapeutic target of RA.
The Journal of Immunology 11/2009; 183(10):6689-97. · 5.79 Impact Factor
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ABSTRACT: Coenzyme Q10 (CoQ10), an endogenous antioxidant, is important in oxidative phosphorylation in mitochondria. It has anti-diabetic and anti-cardiovascular disease effects, but its ability to protect against liver fibrosis has not been studied. Here, we assessed the ability of solubilized CoQ10 to improve dimethylnitrosamine (DMN)-induced liver fibrogenesis in mice. DMN treatments for 3 weeks produced a marked liver fibrosis as assessed by histopathological examination and tissue 4-hydroxyproline content. Solubilized CoQ10 (10 and 30 mg/kg) significantly inhibited both the increases in fibrosis score and 4-hydroxyproline content induced by DMN. Reverse transcription-polymerase chain reaction and Western blot analyses revealed that solubilized CoQ10 inhibited increases in the transforming growth factor-beta1 (TGF-beta1) mRNA and alpha-smooth muscle actin (alpha-SMA) protein by DMN. Interestingly, hepatic glutamate-cysteine ligase (GCL) and glutathione S-transferase A2 (GSTA2) were up-regulated in mice treated with CoQ10. Solubilized CoQ10 also up-regulated antioxidant enzymes such as catalytic subunits of GCL and GSTA2 via activating NF-E2 related factor2 (Nrf2)/antioxidant response element (ARE) in H4IIE hepatoma cells. Moreover, CoQ10's inhibition of alpha-SMA and TGF-beta1 expressions disappeared in Nrf2-null MEF cells. In contrast, Nrf2 overexpression significantly decreased the basal expression levels of alpha-SMA and TGF-beta1 in Nrf2-null MEF cells. These results demonstrated that solubilized CoQ10 inhibited DMN-induced liver fibrosis through suppression of TGF-beta1 expression via Nrf2/ARE activation.
Toxicology and Applied Pharmacology 08/2009; 240(3):377-84. · 4.45 Impact Factor
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ABSTRACT: Sopungyangjae-Tang (SYT) is a traditional Korean decoction used for the treatment of dermatitis. The aim of this study was to confirm whether or not SYT has a preventive effect on the development of atopic dermatitis in dinitrochlorobenzene-applied Nc/Nga mice. SYT was administered orally to Nc/Nga mice, which led to the remarkable suppression of the development of dermatitis, as determined by a histological examination and the serum IgE levels. Moreover, SYT inhibited the production of thymus- and activation-regulated chemokine (TARC) and its mRNA expression in a keratinocyte cell line, HaCaT, which had been stimulated with tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Activation of the nuclear factor-kappaB (NF-kappaB) or activator protein-1 (AP-1) is one of the key steps in the signaling pathways mediating induction of TARC. In this study, SYT selectively suppressed NF-kappaB activation, which may be essential for TARC expression in TNF-alpha/IFN-gamma treated keratinocytes. The inhibitory effect of SYT on NF-kappaB activation and TARC production might be associated with the anti-dermatitic effects of SYT.
Evidence-based Complementary and Alternative Medicine 07/2008; 5(2):173-80. · 4.77 Impact Factor
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ABSTRACT: Ultraviolet (UV) A (320-400 nm), which constitutes more than 90% of UV radiation in the sunlight that reaches the earth's surface, is considered a major cause of human skin photo-aging and skin cancer. Exposure of keratinocytes to UVA has previously been reported to lead to the activation of a variety of epidermal growth factor receptors (EGFR), including ErbB2, and ErbB2 activation is involved in skin tumor development. Here, we demonstrate that ErbB2 expression is enhanced by low-energy UVA (300-3000 mJ/cm(2)) irradiation in the skin tissues of both hairless mice and HaCaT keratinocytes. Luciferase reporter-gene activity using the 756-bp flanking region of the human erbB2 gene was increased by UVA irradiation. UVA irradiation also selectively increased the levels of activator protein (AP)-2 alpha, but not AP-2 beta and AP-2 gamma. The increase in the reporter gene activity of HaCaT cells exposed to UVA was abolished by mutation of the two AP-2 binding sites in the promoter region of the erbB2 gene. Inhibition of cAMP-dependent protein kinase caused complete blockage of ErbB2 induction and AP-2 alpha activation by UVA irradiation. Finally, we reveal that pre-exposure of HaCaT cells to UVA potentiates EGF-inducible anchorage-independent growth of the keratinocytes, which is significantly suppressed by ErbB2 inhibition. These results support the hypothesis that UVA enhances the expression of ErbB2 via cAMP- and protein kinase-dependent AP-2 alpha activation in keratinocytes, which may serve as a key mechanistic basis for the malignant transformation of keratinocytes exposed to UVA irradiation.
Cancer Science 04/2008; 99(3):502-9. · 3.33 Impact Factor
