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Seung-Woo Hong,
Dong-Hoon Jin,
Jae-Sik Shin,
Jai-Hee Moon, Young-Soon Na,
Kyung-Ah Jung,
Seung-Mi Kim,
Jin Cheon Kim,
Kyu-Pyo Kim,
Yong Sang Hong,
Jae-Lyun Lee,
Eun Kyung Choi,
Jung Shin Lee,
Tae Won Kim
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ABSTRACT: Members of the RAF family (ARAF, BRAF, and CRAF/RAF-1) are involved in a variety of cellular activities, including growth, survival, differentiation, and transformation. An oncogene encodes BRAF, the function of which is linked to MEK activation. BRAF is the most effective RAF kinase in terms of induction of MEK/ERK activity. However, the mechanisms involved in BRAF regulation remain unclear. In the present work, we used a tandem affinity purification approach to show that RNF149 (RING finger protein 149) interacts with wild-type BRAF. The latter protein is a RING domain-containing E3 ubiquitin ligase involved in control of gene transcription, translation, cytoskeletal organization, cell adhesion, and epithelial development. We showed that RNF149 bound directly to the C-terminal kinase-containing domain of wild-type BRAF and induced ubiquitination, followed by proteasome-dependent degradation, of the latter protein. Functionally, RNF149 attenuated the increase in cell growth induced by wild-type BRAF. However, RNF149 did not bind to mutant BRAF or induce ubiquitination thereof. Thus, we show that RNF149 is an E3 ubiquitin ligase active on wild-type BRAF.
Journal of Biological Chemistry 05/2012; 287(28):24017-25. · 4.77 Impact Factor
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Seong Joon Park,
Yong Sang Hong,
Jae-Lyun Lee,
Min-Hee Ryu,
Heung Moon Chang,
Kyu-pyo Kim,
Yong Chel Ahn, Young-Soon Na,
Dong-Hoon Jin,
Chang Sik Yu,
Jin Cheon Kim,
Yoon-Koo Kang,
Tae Won Kim
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ABSTRACT: The anti-epidermal growth factor receptor monoclonal antibody cetuximab has been shown to be effective in patients with wild-type KRAS metastatic colorectal cancer (mCRC). Fragment C γ receptor (FcγR) polymorphisms may predict the effectiveness of cetuximab, but this has not been established. This study investigated the clinical relevance of FcγR gene polymorphisms and KRAS status in iri-notecan-refractory mCRC patients treated with cetuximab.
The total number of irinotecan-refractory mCRC patients studied was 118. Among them, 117 and 107 patients were screened for KRAS mutations and genetic polymorphisms of FcγRIIa-131H/R and FcγRIIIa-158V/F, respectively. The association of FcγR polymorphisms and KRAS mutations with clinical outcome was analyzed.
KRAS mutations were found in 33 patients (27.1%). Wild-type KRAS was associated with a better response rate (p < 0.001), longer progression-free survival (p < 0.001) and longer overall survival (p < 0.001). FcγRIIa H/H, H/R and R/R polymorphisms were observed in 54, 49 and 4 patients, respectively, and FcγRIIIa V/V, V/F and F/F polymorphisms were observed in 6, 65, and 36 patients, respectively. Clinical outcomes were not significantly associated with either FcγRIIa or FcγRIIIa polymorphisms or with combinations of KRAS status and FcγR polymorphisms.
The FcγRIIa and FcγRIIIa polymorphisms may not be useful molecular biomarkers for the activity of cetuximab in patients with mCRC.
Oncology 02/2012; 82(2):83-9. · 2.27 Impact Factor
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Young-Soon Na,
Soo-Jin Yang,
Seung-Mi Kim,
Kyung-Ah Jung,
Jai-Hee Moon,
Jae-Sik Shin,
Dok Hyun Yoon,
Yong Sang Hong,
Min-Hee Ryu,
Jae-Lyun Lee,
Jung Shin Lee,
Tae Won Kim
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ABSTRACT: YM155, which inhibits the anti-apoptotic protein survivin, is known to exert anti-tumor effects in various cancers, including prostate and lung cancer. However, there are few reports describing the inhibitory effect of YM155 on human pancreatic cancers that highly express survivin. Here, we tested the effects of YM155 on a variety of cancer cell lines, including pancreatic cancer cells. We found that YM155 exerts an anti-proliferative effect in pancreatic cancer cells, inducing cell death through suppression of XIAP (X-linked inhibitor of apoptosis) as well as survivin without affecting the anti-apoptotic proteins Bcl-xL or Mcl-1. YM155 also inhibited tumor growth in vivo, reducing the size of pancreatic cancer cell line MIAPaCa-2 xenografts by 77.1% on day 31. Western blot analyses further showed that YM155 downregulated phosphoinoside 3-kinase (PI3K) expression and reduced the levels of phosphorylated (activated) extracellular signal-regulated kinase (ERK) and STAT3 (signal transducer and activator of transcription 3) in PANC-1 cells. Interestingly, we also found that YM155 downregulated the epidermal growth factor receptor (EGFR) in various cancer cell lines and induced the EGFR phosphorylation and ubiquitination of EGFR in PANC-1 cells. YM155 also modestly promoted the ubiquitination of survivin and XIAP. Therefore, YM155 acts through modulation of EGFR and survivin expression to subsequently reduce survival. We suggest that YM155 has potential as a therapeutic agent in the treatment of pancreatic cancer.
PLoS ONE 01/2012; 7(6):e38625. · 4.09 Impact Factor
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ABSTRACT: Recent reports have indicated that decursin can induce apoptosis, suppress tumor growth, and inhibit angiogenesis. In this experiment, we investigated how decursin could potentiate the cytotoxic effects of bortezomib in human multiple myeloma cells. We found that decursin inhibited cell viability in U266, MM.1S and ARH77 cells, but not in peripheral blood mononuclear cells (PBMC). Decursin-induced apoptosis through the activation of caspase-8, -9, and -3 in U266 cells. This correlated with the down-regulating of cyclin D1, bcl-2, bcl-xL, survivin, and the vascular endothelial growth factor (VEGF), which are all regulated by the activation of signal transducers and the activator of transcription 3 (STAT3). Indeed, decursin inhibited constitutive STAT3 activation through inhibition of the activation of Janus-activated kinase 2 (JAK2) in U266 cells. In addition, decursin inhibited interleukin-6-inducible STAT3 activation in a time-dependent manner in MM.1S cells. Interestingly, decursin significantly potentiated the apoptotic effects of bortezomib in U266 cells. These effects of decursin were correlated with the suppression of constitutive STAT3 activation in U266 cells. Overall, these results suggest that decursin is a novel blocker of STAT3 activation and it may be a potential candidate for overcoming chemo-resistance through suppression of this signaling.
Cancer letters 02/2011; 301(1):29-37. · 4.86 Impact Factor
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Young-Soon Na,
Seung-Mi Kim,
Kyung-Ah Jung,
Soo-Jin Yang,
Yong Sang Hong,
Min-Hee Ryu,
Seonggu Ro,
Dong-Hyung Cho,
Jin Cheon Kim,
Dong-Hoon Jin,
Jung Shin Lee,
Tae Won Kim
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ABSTRACT: Chemotherapies for colon cancer have recently advanced. However, there is still a need to develop agents and identify effective regimens for better treatments of colon cancer. Histone deacetylase inhibitors (HDACIs) have shown potential as anti-cancer agents. We investigated the anti-tumor effects of CG2 (an HDACI) in combination with irinotecan, 5-FU, or oxaliplatin. Combinations of CG2 with SN38 (the active form of irinotecan), 5FU, or oxaliplatin were more effective than the agents alone when used to inhibit the growth of HCT116 cells. The protein expressions of acetyl-H3, p21, caspase-3, -8, and -9, PARP, and XIAP were affected in a time- and dose-dependent manner in HCT116 cells treated with the CG2 alone or combined CG2 and SN-38. In HCT116 xenografts, the HDACI CG2 in combination with irinotecan dramatically inhibited tumor growth without showing additive toxicity. These data indicate that CG2 together with irinotecan is a promising combination novel treatment for colon cancer.
Oncology Reports 12/2010; 24(6):1509-14. · 1.84 Impact Factor
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Young-Soon Na,
Kyung-Ah Jung,
Seung-Mi Kim,
Yong Sang Hong,
Min-Hee Ryu,
Se Jin Jang,
Dae Hyuk Moon,
Dong-Hyung Cho,
Jin Cheon Kim,
Jung Shin Lee,
Tae Won Kim
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ABSTRACT: Histone deacetylase inhibitors (HDACIs), such as PXD101 and suberoylanilide hydroxamic acid, inhibit proliferation and stimulate apoptosis of tumor cells. The enhanced effectiveness of chemotherapy or radiotherapy when combined with HDACIs has been observed in several cancers. In this study, we investigated the antitumor effect of PXD101 combined with irinotecan in colon cancer.
HCT116 and HT29 colon cancer cells for cell viability assay were treated with PXD101 and/or SN-38, the active form of irinotecan. Antitumor effects of HCT116 and HT29 xenografts treated with these combinations were evaluated. [(18)F]FLT-PET was used to detect early responses to PXD101 and irinotecan in colon cancer.
PXD101 and SN38 possessed dose-dependent antiproliferative activity against HCT116 and HT29 cells and exerted a synergistic effect when used in combination. In xenografted mice, PXD101 in combination with irinotecan dramatically inhibited tumor growth without causing additive toxicity. Apoptotic effects on xenograft tumors were greater with combined treatment than with irinotecan alone. [(18)F]FLT-PET imaging revealed a 64% decrease in [(18)F]FLT uptake in tumors of HCT116 xenograft-bearing mice treated with a combination of PXD101 and irinotecan, indicating a decrease in thymidine kinase 1 (TK1) activity. These results were supported by Western blot analyses showing a decrease in tumor thymidine kinase 1 protein levels, suggesting that [(18)F]FLT-PET can be used to non-invasively detect early responses to these agents.
These data show that PXD101 increases the cytotoxic activity of irinotecan in in vitro and in vivo colon cancer models and suggest these agent combinations should be explored in the treatment of colon cancer.
Cancer Chemotherapy and Pharmacology 11/2010; 68(2):389-98. · 2.83 Impact Factor
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ABSTRACT: Hereditary colorectal cancer develops through a series of well-defined genetic and histological changes. However, elucidation of the canonical pathway based on hereditary colorectal cancer has not provided a clear explanation of the molecular mechanisms of sporadic colorectal cancer. To identify the alterative pathways involved in sporadic colorectal tumorigenesis, we performed gene expression analysis in patients with sporadic colorectal tumors. A comparison analysis of gene expression profiles revealed a pattern of upregulation of small proline rich repeat protein 3 (SPRR3) in tumor samples. SPRR3 has previously been reported to be downregulated in esophageal cancer. However, in the present study, we observed that SPRR3 was strongly upregulated in 31 of 35 samples of sporadic colorectal tumors (88%). We also determined that overexpression of SPRR3 not only accelerates colorectal cancer cell proliferation but also is associated with lymphovascular invasion in colorectal cancer. Moreover, AKT was activated and p53 levels were decreased in cells that overexpressed SPRR3. In contrast to the pattern seen in esophageal cancer, these results suggest that increased expression of SPRR3 is involved in colorectal tumorigenesis.
Molecular Medicine 03/2010; 16(7-8):271-7. · 3.76 Impact Factor
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Byeong Seok Sohn,
Tae Won Kim,
Jae-Lyun Lee,
Min-Hee Ryu,
Heung Moon Chang,
Yoon-Koo Kang,
Hyo Suk Park, Young-Soon Na,
Se Jin Jang,
Jin Cheon Kim,
Jung Shin Lee
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ABSTRACT: This study evaluated the clinical relevance of KRAS and BRAF mutational status in 66 irinotecan-refrac- tory Korean metastatic colorectal cancer (mCRC) patients treated with cetuximab-plus-irinotecan-based chemotherapy.
A total of 66 irinotecan-refractory mCRC patients treated with cetuximab-plus-irinotecan-based chemotherapy were included. Tumors were screened for KRAS mutations (codons 12 and 13) and a BRAF mutation (V600E) using direct sequencing and the Snapshot assay.
The objective response rate (RR) for treatment was 21.2% (14/66) and skin rashes were observed in 43 (65.2%) of the 66 patients. A KRAS mutation was detected in 27 (40.9%) tumors, and was associated with lower RR (wild-type vs. mutated KRAS: 33.3 vs. 3.7%, p = 0.005) and shorter progression-free survival (PFS) and overall survival (OS; PFS: 6.4 vs. 2.0 months, p = 0.005; OS: 17.8 vs. 7.1 months, p = 0.001). Severe skin toxicity was associated with better RR and longer PFS and OS. BRAF mutations were not detected. Multivariate analysis revealed that KRAS status and skin toxicity were independent predictive factors of PFS and OS.
This study indicates the clinical relevance of KRAS mutations in predicting the efficacy of cetuximab-plus-irinotecan-based chemotherapy in irinotecan-refractory Korean mCRC patients.
Oncology 10/2009; 77(3-4):224-30. · 2.27 Impact Factor
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ABSTRACT: Parkinson's disease (PD) is characterized by a selective loss of dopamine-producing neurons in the substantia nigra (SN), which in turn results in dopamine depletion in the striatum, and the presence of neuronal cytoplasmic inclusions known as Lewy bodies (LBs). Alpha-synuclein is a presynaptic protein that accumulates abnormally in LBs and is seen predominantly in cases of dementia with LBs. Although the central role of alpha-synuclein in neurodegeneration has been previously demonstrated by the discovery of missense alpha-synuclein mutations in familial PD, the specific mechanism by which alpha-synuclein contributes to these diseases remains unclear. In the present study, we examined whether alpha-synuclein affects the downstream signaling of dopamine D2 receptor (D2R). In CHO cells stably transfected with D2Rs, alpha-synuclein enhanced dopamine D2-agonist-mediated inhibition of adenylate cyclase, which consequently affected its downstream cAMP-responsive element (CRE)-mediated gene transcription, while C-terminal deletion mutant of alpha-synuclein did not. Our study suggests that the alpha-synuclein enhances the dopamine-mediated intracellular signaling pathways by D2R, thus provide a possible mechanism in presynaptic regulation of the synaptic homeostasis in the dopaminergic neurotransmission.
Brain Research 01/2007; 1124(1):5-9. · 2.73 Impact Factor
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ABSTRACT: Because the dopaminergic pathways in the midbrain have been closely associated with serious neuropsychiatric disorders, the elucidation of the mechanisms underlying dopaminergic neuronal development should provide some important clues for related disorders. In mice lacking the dopamine D2 receptor (D2R-/-), stereological cell counting analysis showed that the number of mesencephalic tyrosine hydroxylase (TH) cells was significantly low during ontogeny, compared with that observed in wild-type (WT) mice, thereby indicating an alteration in dopaminergic neuronal development in the absence of D2R. The results of immunohistochemical and reverse transcription-PCR analyses revealed that the expression of Nurr1, an orphan nuclear receptor, as well as Ptx3 expression, was selectively reduced in D2R-/- mice during the embryonic stage. A reporter gene assay using the Nur response element linked to the luciferase reporter gene indicated that the stimulation of D2R results in the activation of the Nurr1-mediated reporter gene. This D2R-mediated Nur response element-dependent transcriptional activity was regulated via the activation of extracellular signal-regulated kinase (ERK). Furthermore, quinpirole treatment was shown to elicit an increase in the number of TH-positive neurons, as well as the neuritic extension of TH neurons, coupled with ERK activation and Nurr1 activation in the TH-positive neurons in primary mesencephalic cultures from WT mice. However, this regulation was not detected in the D2R-/- mice. These results suggest that signaling through D2R in association with Nurr1 using ERK, plays a critical role in mesencephalic dopaminergic neuronal development.
Journal of Neuroscience 05/2006; 26(17):4567-76. · 7.11 Impact Factor
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ABSTRACT: The human immunodeficiency virus (HIV) nef gene encodes a 27 kDa myristoylated cytosolic protein that has an important role in the pathogenesis of AIDS. One function of Nef is the down-regulation of CD4 and MHC class I surface molecules in HIV-infected cells. Nef directly isolated from an infected individual (KS2), who could be defined as a long-term non-progressor, was compared with Nef from a standard laboratory strain, HIV-1 NL4-3. KS2 Nef protein was characterized by its lowered ability to down-regulate CD4, while still maintaining the ability to down-regulate MHC class I. The ability of KS2 Nef to down-regulate CD4 was more prominent when CD4 was measured 2-3 days after transfer of the nef gene to the target cells, and also when the effect was measured in CD4(+)-enriched primary T cells. The amino acid sequence analysis indicated that the most notable feature of KS2 Nef was lack of the two glutamic acids: the EE(155) region. When the EE(155) region was added to KS2 Nef, the CD4 down-regulation ability was increased almost to the level of NL4-3 Nef. Conversely, when the EE(155) region was deleted from NL4-3, its CD4 down-regulation ability was dramatically impaired. These data suggested that the EE(155) region plays an important role(s) in the down-regulation of CD4 by Nef protein and also that primary nef sequences could be very useful in identifying the original biological functions of Nef in vivo.
Journal of General Virology 07/2004; 85(Pt 6):1451-61. · 3.36 Impact Factor
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ABSTRACT: As an alternative method to the conventional therapies for Hunter's syndrome, which is a lethal lysosomal storage disorder, we have developed gene delivery vehicles using a series of retroviral vectors. The objective of this study was to develop a safe and efficient retroviral vector and to optimize conditions for efficient transduction of human bone marrow CD34+ stem cells using our vector.
We constructed three types of MLV-based retroviral vectors expressing iduronate-2-sulfatase (IDS) which is deficient in patients suffering from Hunter's syndrome: MIN-IDS and MIM-IDS, which express IDS along with bacterial neo and human MDR genes, respectively, and MT-IDS lacking any selectable marker. Respective producer lines were derived from the packaging line, PG13, and compared for viral titer and levels of gene expression. After comparing, the retroviral vector, MT-IDS, was used to transduce human bone marrow CD34+ stem cells on fibronectin under various MOIs.
In comparison, MT-IDS not only produced the highest viral titer (close to 10(7) cfu/ml), but also showed the highest level of gene expression in various transduction assays and RNA analysis. When 1.5 x 10(5) human CD34+ bone marrow cells were transduced with MT-IDS under the most optimal MOIs, about 80% of total colony forming units were shown to contain the IDS cDNA.
Minimum-sized retroviral vector that contains no selective marker as well as a viral coding sequences could drive a high level of gene expression, be produced efficiently from the producer line, and enter hematopoietic cells at a high frequency. Our data suggest the great potential for using MT-based vector(s) in a gene therapy trial for Hunter's syndrome utilizing human CD34+ stem cells as target cells.
The Journal of Gene Medicine 02/2003; 5(1):18-29. · 2.48 Impact Factor
