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Foxp3 is a key downstream regulator of p53-mediated cellular senescence
Kim, J-E,Shin, J-S,Moon, J-H,Hong, S-W,Jung, D-J,Kim, J H,Hwang, I-Y,Shin, Y J,Gong, E-Y,Lee, D H,Kim, S-M,Lee, E Y,Kim, Y S,Kim, D,Hur, D,Kim, T W,Kim, K-p,Jin, D-H,Lee, W-J Macmillan Publishers Limited 2017 Oncogene Vol.36 No.2
<P>The downstream events and target genes of p53 in the process of senescence are not fully understood. Here, we report a novel function of the forkhead transcription factor Foxp3, which is a key player in mediating T-cell inhibitory functions, in p53-mediated cellular senescence. The overexpression of Foxp3 in mouse embryonic fibroblasts (MEFs) accelerates senescence, whereas Foxp3 knockdown leads to escape from p53-mediated senescence in p53-expressing MEFs. Consistent with these results, Foxp3 expression resulted in the induction of senescence in epithelial cancer cells, including MCF7 and HCT116 cells. Foxp3 overexpression also increased the intracellular levels of reactive oxygen species (ROS). The ROS inhibitor N-acetyl-L-cysteine rescued cells from Foxp3-expression-induced senescence. Furthermore, the elevated ROS levels that accompanied Foxp3 overexpression were paralleled by an increase in p21 expression. Knockdown of p21 in Foxp3-expressing MEFs abrogated the Foxp3-dependent increase in ROS levels, indicating that Foxp3 acts through the induction of p21 and the subsequent ROS elevation to trigger senescence. Collectively, these results suggest that Foxp3 is a downstream target of p53 that is sufficient to induce p21 expression, ROS production and p53-mediated senescence.</P>
p34 is a novel regulator of the oncogenic behavior of NEDD4-1 and PTEN
Hong, S-W,Moon, J-H,Kim, J-S,Shin, J-S,Jung, K-A,Lee, W-K,Jeong, S-Y,Hwang, J J,Lee, S-J,Suh, Y-A,Kim, I,Nam, K-Y,Han, S,Kim, J E,Kim, K-p,Hong, Y S,Lee, J-L,Lee, W-J,Choi, E K,Lee, J S,Jin, D-H,Kim, Macmillan Publishers Limited 2014 CELL DEATH AND DIFFERENTIATION Vol.21 No.1
PTEN is one of the most frequently mutated or deleted tumor suppressors in human cancers. NEDD4-1 was recently identified as the E3 ubiquitin ligase for PTEN; however, a number of important questions remain regarding the role of ubiquitination in regulating PTEN function and the mechanisms by which PTEN ubiquitination is regulated. In the present study, we demonstrated that p34, which was identified as a binding partner of NEDD4-1, controls PTEN ubiquitination by regulating NEDD4-1 protein stability. p34 interacts with the WW1 domain of NEDD4-1, an interaction that enhances NEDD4-1 stability. Expression of p34 promotes PTEN poly-ubiquitination, leading to PTEN protein degradation, whereas p34 knockdown results in PTEN mono-ubiquitination. Notably, an inverse correlation between PTEN and p34/NEDD4-1 levels was confirmed in tumor samples from colon cancer patients. Thus, p34 acts as a key regulator of the oncogenic behavior of NEDD4-1 and PTEN.
Kim, J C,Ha, Y J,Roh, S A,Choi, E Y,Yoon, Y S,Kim, K P,Hong, Y S,Kim, T W,Cho, D H,Kim, S Y,Kim, Y S Nature Publishing Group 2013 The British journal of cancer Vol.108 No.9
<P><B>Background:</B></P><P>Surrogate biomarkers for metastatic colorectal cancer (mCRC) are urgently needed to achieve the best outcomes for targeted therapy.</P><P><B>Methods:</B></P><P>A clinical association analysis was performed to examine the three single-nucleotide polymorphisms (SNPs) that were previously proposed as markers of chemosensitivity to the cetuximab (124 patients) and bevacizumab regimens (100 patients) in mCRC patients. In addition, biological correlations were examined for the candidate SNPs in terms of their regulatory pathway.</P><P><B>Results:</B></P><P>For cetuximab regimens, patients homozygous for the wild-type alleles (<I>GG</I>) of <I>LIFR rs3729740</I> exhibited a 1.9 times greater overall response rate (ORR) and 1.4 months longer progression-free survival (PFS) than those homozygous or heterozygous for the mutant allele (<I>GA</I> and <I>AA</I>; <I>P</I>=0.022 and 0.027, respectively). For bevacizumab regimens, patients homozygous for the minor alleles (<I>TT</I>) of <I>ANXA11 rs1049550</I> exhibited an ORR twice as high as those homozygous or heterozygous for the ancestral allele (<I>CC</I> and <I>CT</I>; <I>P</I>=0.031). Overall response rate gain was achieved up to 10% in patients with wild-type <I>LIFR rs3729740</I> patients either with wild-type <I>KRAS</I> or skin toxicity (<I>P</I>=0.001) respectively. Specifically in clones treated with cetuximab and bevacizumab regimens, active p-ERK and MMP-9 expressions were significantly reduced in clones expressing wild-type <I>LIFR rs3729740</I> (<I>P</I>=0.044) and in those expressing minor-type <I>ANXA11 rs1049550</I> (<I>P</I>=0.007), respectively.</P><P><B>Conclusion:</B></P><P><I>LIFR rs3729740</I> and possibly <I>ANXA11 rs1049550</I> may be useful as biomarkers for predicting whether mCRC patients are sensitive to relevant target regimens, although further validation in large cohorts is needed.</P>
Lee, Y.‐,S.,Choi, K.‐,M.,Choi, M.‐,H.,Ji, S.‐,Y.,Lee, S.,Sin, D.‐,M.,Oh, K.‐,W.,Lee, Y.‐,M.,Hong, J.‐,T.,Yun, Y.‐,P.,Yoo, H.‐,S. Blackwell Publishing Ltd 2011 Cell proliferation Vol.44 No.4
<P><B>Abstract</B></P><P><B>Objectives: </B> Melanoma is the most aggressive form of skin cancer, and it resists chemotherapy. Candidate drugs for effective anti‐cancer treatment have been sought from natural resources. Here, we have investigated anti‐proliferative activity of myriocin, serine palmitoyltransferase inhibitor, in the <I>de novo</I> sphingolipid pathway, and its mechanism in B16F10 melanoma cells.</P><P><B>Material and methods: </B> We assessed cell population growth by measuring cell numbers, DNA synthesis, cell cycle progression, and expression of cell cycle regulatory proteins. Ceramide, sphingomyelin, sphingosine and sphingosine‐1‐phosphate levels were analysed by HPLC.</P><P><B>Results: </B> Myriocin inhibited proliferation of melanoma cells and induced cell cycle arrest in the G<SUB>2</SUB>/M phase. Expressions of cdc25C, cyclin B1 and cdc2 were decreased in the cells after exposure to myriocin, while expression of p53 and p21<SUP>waf1/cip1</SUP> was increased. Levels of ceramide, sphingomyelin, sphingosine and sphingosine‐1‐phosphate in myriocin‐treated cells after 24 h were reduced by approximately 86%, 57%, 75% and 38%, respectively, compared to levels in control cells.</P><P><B>Conclusions: </B> Our results suggest that inhibition of sphingolipid synthesis by myriocin in melanoma cells may inhibit expression of cdc25C or activate expression of p53 and p21<SUP>waf1/cip1</SUP>, followed by inhibition of cyclin B1 and cdc2, resulting in G<SUB>2</SUB>/M arrest of the cell cycle and cell population growth inhibition. Thus, modulation of sphingolipid metabolism by myriocin may be a potential target of mechanism‐based therapy for this type of skin cancer.</P>
Lee, J.‐,E.,Hong, E.‐,J.,Nam, H.‐,Y.,Kim, J.‐,W.,Han, B.‐,G.,Jeon, J.‐,P. Blackwell Publishing Ltd 2011 Cell proliferation Vol.44 No.1
<P><B>Abstract</B></P><P><B>Objective: </B> MicroRNAs (miRNAs) are negative regulators of gene expression that play important roles in cell processes such as proliferation, development and differentiation. Recently, it has been reported that miRNAs are related to development of carcinogenesis. The aim of this study was to identify miRNAs associated with terminal immortalization of Epstein–Barr virus (EBV)‐transformed lymphoblastoid cell line (LCL) and associated clinical traits.</P><P><B>Material and Methods: </B> Hence, we performed miRNA microarray approach with early‐ (p6) and late‐passage (p161) LCLs.</P><P><B>Results and Conclusion: </B> Microarray data showed that nine miRNAs (miR‐20b*, miR‐28‐5p, miR‐99a, miR‐125b, miR‐151‐3p, miR‐151:9.1, miR‐216a, miR‐223* and miR‐1296) were differentially expressed in most LCLs during long‐term culture. In particular, miR‐125b was up‐regulated in all the tested late‐passage LCLs. miR‐99a, miR‐125b, miR‐216a and miR‐1296 were putative negative regulators of <I>RASGRP3</I>, <I>GPR160</I>, <I>PRKCH</I> and <I>XAF1</I>, respectively, which were found to be differentially expressed in LCLs during long‐term culture in a previous study. Linear regression analysis showed that miR‐200a and miR‐296‐3p correlated with triglyceride and HbA1C levels, respectively, suggesting that miRNA signatures of LCLs could provide information on the donor’s health. In conclusion, our study suggests that expression changes of specific miRNAs may be required for terminal immortalization of LCLs. Thus, differentially expressed miRNAs would be a potential marker for completion of cell immortalization during EBV‐mediated tumorigenesis.</P>
실리타 코팅된 CI particle을 이용한 SUS 304의 초정밀 연마
홍광표(K. P. Hong),이정원(J. W. Lee),하석재(S. J. Ha),조용규(Y. K. Cho),이현주(H. J. Lee),조명우(M. W. Cho),최형진(H. J. Choi),제태진(T.J.Je) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Recently, the magnetorheological (MR) polishing method has been performed as a new ultra precision polishing technique for many industrial applications. This method uses MR fluids, which consists of carbonyl iron (CI) particle, carrier fluid, additives and dispersion stabilizer. However, CI particle are easily oxidized in water. This problem leads to unpredictable polishing results and reduces the life of MR fluid. To solve the problem, in this study, Silica-coated CI particles were used for MR polishing. Their rheological properties were analyzed to compare silica coated MR fluid and uncoated MR fluid. As a result, in terms of surface roughness, MR polishing with silica-coated CI based MR fluid (Ra=1.89nm) shows a better than that of uncoated CI based MR fluid.