Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Long noncoding RNAs (lncRNAs) play pivotal roles in tumor development. To identify dysregulated lncRNAs in gastric cancer (GC), we analyzed genome-wide trimethylation of histone H3 lysine 4 (H3K4me3) to screen for transcriptionally active lncRNA genes in the non-tumorous gastric mucosa of patients with GC and healthy individuals. We found that H3K4me3 at TM4SF1-AS1 was specifically upregulated in GC patients and that the expression of TM4SF1-AS1 was significantly elevated in primary and cultured GC cells. TM4SF1-AS1 contributes to GC cell growth in vitro and in vivo, and its oncogenic function is mediated, at least in part, through interactions with purine-rich element-binding protein α (Pur-α) and Y-box binding protein 1 (YB-1). TM4SF1-AS1 also activates interferon signaling in GC cells, which is dependent on Pur-α and RIG-I. Chromatin isolation by RNA purification (ChIRP)-mass spectrometry demonstrated that TM4SF1-AS1 was associated with several stress granule (SG)-related proteins, including G3BP2, RACK1, and DDX3. Notably, TM4SF1-AS1 promoted SG formation and inhibited apoptosis in GC cells by sequestering RACK1, an activator of the stress-responsive MAPK pathway, within SGs. TM4SF1-AS1-induced SG formation and apoptosis inhibition are dependent on Pur-α and YB-1. These findings suggested that TM4SF1-AS1 contributes to tumorigenesis by enhancing SG-mediated stress adaptation.

Other Link： https://www.nature.com/articles/s41419-023-05953-3

DOI： 10.1038/s41419-023-05953-3

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Background and Aim

The tumor microenvironment plays an essential role in the development and progression of colorectal cancer (CRC). We recently reported that crosstalk between CRC cells and tumor‐associated macrophages (TAMs) via serum amyloid A1 (SAA1) promotes invasion by T1 CRCs. In the present study, we aimed to clarify the role of neutrophils in early CRCs.

Methods

Immunohistochemical analysis of CD66b, chemokine CXC motif ligand 8 (CXCL8 or interleukin‐8, IL‐8) and matrix metalloproteinase‐9 (MMP‐9) was performed using primary T1 CRCs (n = 49). The HL‐60 human promyelocytic leukemia cell line and THP‐1 human monocytic leukemia cell line were used to obtain neutrophil‐like and macrophage‐like cells, respectively. Boyden chamber assays were used to analyze cell migration and invasion, and quantitative RT‐PCR was used to analyze gene expression.

Results

Immunohistochemical analysis revealed accumulation of neutrophils at the SAA1‐positive invasive front of T1 CRCs. Experiments using HL‐60 cells suggested that treatment with SAA1 induced neutrophil migration and expression of CXCL8 and MMP‐9 in neutrophils and that neutrophils promote CRC cell migration and invasion. Immunohistochemistry confirmed accumulation of CXCL8‐ or MMP‐9‐positive neutrophils at the SAA1‐positive invasive front of T1 CRCs. Moreover, co‐culture experiments using CRC, THP‐1 and HL‐60 cells suggested that CRC cells activated by macrophages upregulate CXCL8 and MMP‐9 in neutrophils.

Conclusions

Our results suggest that interplay between macrophages and CRC cells leads to recruitment of neutrophils to the invasive front of T1 CRCs and that SAA1 secreted by CRC cells activate neutrophils to promote invasion.

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jgh.16055

DOI： 10.1111/jgh.16055

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Publishing type：Research paper (scientific journal)   Publisher：International Institute of Anticancer Research  

DOI： 10.21873/anticanres.15062

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Recent studies revealed that colorectal tumors are composed of genetically diverse subclones. We aimed to clarify whether the surface microstructures of colorectal tumors are associated with genetic intratumoral heterogeneity (ITH). METHODS: The surface microstructures (pit patterns) of colorectal tumors were observed using magnifying endoscopy, and biopsy specimens were obtained from respective areas when tumors exhibited multiple pit patterns. A total of 711 specimens from 477 colorectal tumors were analyzed for BRAF, KRAS and TP53 mutations using pyrosequencing and direct sequencing. A panel of cancer-related genes was analyzed through targeted sequencing in 7 tumors. RESULTS: Colorectal tumors with multiple pit patterns exhibited more advanced pit patterns and higher frequencies of KRAS and/or TP53 mutations than tumors with a single pit pattern. In tumors with multiple pit patterns, mutations were observed as public (common to all areas) or private (specific to certain areas), and private KRAS and/or TP53 mutations were often variable and unrelated to the pit pattern grade. Notably, invasive CRCs frequently exhibited public TP53 mutations, even in adenomatous areas, which is indicative of their early malignant potential. Targeted sequencing revealed additional public and private mutations in tumors with multiple pit patterns, indicating their single clonal origin. CONCLUSIONS: Our results suggest intratumoral pit pattern variation does not simply reflect the process of colorectal tumor evolution, but instead represents genetically diverse subclones, and this diversity may be associated with malignant potential.

DOI： 10.1007/s00535-018-1481-z

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Recent studies have shown that long noncoding RNAs (lncRNAs) have pivotal roles in human malignancies, although their significance in oral squamous cell carcinoma (OSCC) is not fully understood. In the present study, we identified lncRNAs functionally associated with OSCC. By analyzing RNA-seq datasets obtained from primary head and neck squamous cell carcinoma (HNSCC), we identified 15 lncRNAs aberrantly expressed in cancer tissues. We then validated their expression in 18 OSCC cell lines using qRT-PCR and identified 6 lncRNAs frequently overexpressed in OSCC. Among those, we found that knocking down DLEU1 (deleted in lymphocytic leukemia 1) strongly suppressed OSCC cell proliferation. DLEU1 knockdown also suppressed migration, invasion, and xenograft formation by OSCC cells, which is suggestive of its oncogenic functionality. Microarray analysis revealed that DLEU1 knockdown significantly affects expression of a number of cancer-related genes in OSCC cells, including HAS3, CD44, and TP63, suggesting that DLEU1 regulates HA-CD44 signaling. Expression of DLEU1 was elevated in 71% of primary OSCC tissues, and high DLEU1 expression was associated with shorter overall survival of HNSCC patients. These data suggest that elevated DLEU1 expression contributes to OSCC development, and that DLEU1 may be a useful therapeutic target in OSCC.

DOI： 10.1038/s41419-018-0893-2

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In this study, we identified microRNAs (miRNAs) involved in cisplatin (CDDP) resistance in bladder cancer (BCa). After establishing CDDP-resistant BCa cell lines (T24RC and EJ138RC), TaqMan arrays revealed that members of the miR-200 family (miR-200b, miR-200a and miR-429) were downregulated in T24RC as compared to parental T24 cells. miR-200b was associated with CDDP sensitivity in BCa cells, and its downregulation was associated with CpG island hypermethylation. Pharmacological demethylation using 5-aza-2'-deoxycytidine restored miR-200b expression, and the combination of 5-aza-2'-deoxycytidine + CDDP strongly inhibited T24RC cell proliferation. Microarray analysis revealed that miR-200b + CDDP induced genes involved in CDDP sensitivity or cytotoxicity, including IGFBP3, ICAM1 and TNFSF10, in the resistant cells. Expression and DNA methylation of miR-200b were inversely associated in primary BCa, and low expression/high methylation was associated with poor overall survival. These results suggest downregulation of miR-200b is associated with CDDP resistance in BCa. Epigenetic silencing of miR-200b may be a marker of CDDP resistance and a useful therapeutic target for overcoming CDDP resistance in BCa.

DOI： 10.18632/oncotarget.25326

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Although dysregulation of microRNAs (miRNAs/miRs) is a common feature of human malignancies, its involvement in gastrointestinal stromal tumors (GISTs) is not fully understood. The present study aimed to identify the miRNAs that perform a role in GIST metastasis. miRNA expression profiles from a series of 32 primary GISTs were analyzed using microarrays, and miR-186 was observed to be downregulated in tumors exhibiting metastatic recurrence. Reverse transcription-quantitative polymerase chain reaction analysis of an independent cohort of 100 primary GISTs revealed that low miR-186 expression is associated with metastatic recurrence and a poor prognosis. Inhibition of miR-186 in GIST-T1 cells promoted cell migration. Gene expression microarray analysis demonstrated that miR-186 inhibition upregulated a set of genes implicated in cancer metastasis, including insulin-like growth factor-binding protein 3, AKT serine/threonine kinase 2, hepatocyte growth factor receptor, CXC chemokine receptor 4 and epidermal growth factor-containing fibulin-like extracellular matrix protein 1. These results suggest that the downregulation of miR-186 is involved in the metastatic recurrence of GISTs, and that miR-186 levels could potentially be a predictive biomarker for clinical outcome.

DOI： 10.3892/ol.2017.6911

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Long noncoding RNAs (lncRNAs) have emerged as key components in multiple cellular processes, although their physiological and pathological functions are not fully understood. To identify cancer-related lncRNAs, we screened for those that are epigenetically silenced in colorectal cancer (CRC). Through a genome-wide analysis of histone modifications in CRC cells, we found that the transcription start sites (TSSs) of 1,027 lncRNA genes acquired trimethylation of histone H3 lysine 4 (H3K4me3) after DNA demethylation. Integrative analysis of chromatin signatures and the DNA methylome revealed that the promoter CpG islands (CGIs) of 66 lncRNA genes contained cancer-specific methylation. By validating the expression and methylation of lncRNA genes in CRC cells, we ultimately identified 20 lncRNAs, including ZNF582-AS1, as targets of epigenetic silencing in CRC. ZNF582-AS1 is frequently methylated in CRC cell lines (87.5%), primary CRCs (77.2%), colorectal adenomas (44.7%) and advanced adenomas (87.8%), suggesting that this methylation is an early event during colorectal tumorigenesis. Methylation of ZNF582-AS1 is associated with poor survival of CRC patients, and ectopic expression of ZNF582-AS1 suppressed colony formation by CRC cells. Our findings offer insight into the association between epigenetic alterations and lncRNA dysregulation in cancer and suggest that ZNF582-AS1 may be a novel tumor-suppressive lncRNA.

DOI： 10.1038/srep26699

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Aberrant DNA methylation is commonly observed in colorectal cancer (CRC), but the underlying mechanism is not fully understood. 5-hydroxymethylcytosine levels and TET1 expression are both reduced in CRC, while epigenetic silencing of TET1 is reportedly associated with the CpG island methylator phenotype. In the present study, we aimed to clarify the relationship between loss of TET1 and aberrant DNA methylation in CRC. Stable TET1 knockdown clones were established using Colo320DM cells, which express high levels of TET1, and HCT116 cells, which express TET1 at a level similar to that in normal colonic tissue. Infinium HumanMethylation450 BeadChip assays revealed increased levels of 5-methylcytosine at more than 10,000 CpG sites in TET1-depleted Colo320DM cells. Changes in DNA methylation were observed at various positions within the genome, including promoters, gene bodies and intergenic regions, and the altered methylation affected expression of a subset of genes. By contrast, TET1 knockdown did not significantly affect DNA methylation in HCT116 cells. However, TET1 depletion was associated with attenuated effects of 5-aza-2'-deoxycytidine on gene expression profiles in both cell lines. These results suggest that loss of TET1 may induce aberrant DNA methylation and may attenuate the effect of 5-aza-2'-deoxycytidine in CRC cells.

DOI： 10.1371/journal.pone.0168281

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BACKGROUND: Dysregulation of microRNA (miRNA) has been implicated in gastrointestinal stromal tumors (GISTs) but the mechanism is not fully understood. In this study, we aimed to explore the involvement of epigenetic alteration of miRNA genes in GISTs. METHODS: GIST-T1 cells were treated with 5-aza-2'-deoxycytidine (5-aza-dC) and 4-phenylbutyric acid (PBA), after which miRNA expression profiles were analyzed using TaqMan miRNA arrays. DNA methylation was then analyzed using bisulfite pyrosequencing. The functions of miRNAs were examined using MTT assays, wound-healing assays, Boyden chamber assays and Matrigel invasion assays. Gene expression microarrays were analyzed to assess effect of ectopic miRNA expression in GIST-T1 cells. RESULTS: Of the 754 miRNAs analyzed, 61 were significantly upregulated in GIST-T1 cells treated with 5-aza-dC plus PBA. Among those, 21 miRNA genes were associated with an upstream CpG island (CGI), and the CGIs of miR-34a and miR-335 were frequently methylated in GIST-T1 cells and primary GIST specimens. Transfection of miR-34a or miR-335 mimic molecules into GIST-T1 cells suppressed cell proliferation, and miR-34a also inhibited migration and invasion by GIST-T1 cells. Moreover, miR-34a downregulated a number of predicted target genes, including PDGFRA. RNA interference-mediated knockdown of PDGFRA in GIST-T1 cells suppressed cell proliferation, suggesting the tumor suppressive effect of miR-34a is mediated, at least in part, through targeting PDGFRA. CONCLUSIONS: Our results suggest that miR-34a and miR-335 are candidate tumor suppressive miRNAs in GISTs, and that they are frequent targets of epigenetic silencing in GISTs.

DOI： 10.1371/journal.pone.0133754

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BACKGROUND: Dysregulation of microRNAs (miRNAs) has been implicated in bladder cancer (BCa), although the mechanism is not fully understood. OBJECTIVE: We aimed to explore the involvement of epigenetic alteration of miRNA expression in BCa. DESIGN, SETTING, AND PARTICIPANTS: Two BCa cell lines (T24 and UM-UC-3) were treated with 5-aza-2'-deoxycytidine (5-aza-dC) and 4-phenylbutyric acid (PBA), after which their miRNA expression profiles were analyzed using a TaqMan array (Life Technologies, Carlsbad, CA, USA). Bisulfite pyrosequencing was used to assess miRNA gene methylation in 5 cancer cell lines, 83 primary tumors, and 120 preoperative and 47 postoperative urine samples. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of the miRNA gene panel. RESULTS AND LIMITATIONS: Of 664 miRNAs examined, 146 were upregulated by 5-aza-dC plus PBA. CpG islands were identified in the proximal upstream of 23 miRNA genes, and 12 of those were hypermethylated in cell lines. Among them, miR-137, miR-124-2, miR-124-3, and miR-9-3 were frequently and tumor-specifically methylated in primary cancers (miR-137: 68.7%; miR-124-2: 50.6%; miR-124-3: 65.1%; miR-9-3: 45.8%). Methylation of the same four miRNAs in urine specimens enabled BCa detection with 81% sensitivity and 89% specificity; the area under the ROC curve was 0.916. Ectopic expression of silenced miRNAs in BCa cells suppressed growth and cell invasion. CONCLUSIONS: Our results indicate that epigenetic silencing of miRNA genes may be involved in the development of BCa and that methylation of miRNA genes could be a useful biomarker for cancer detection.

DOI： 10.1016/j.eururo.2012.11.030

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Altered expression of microRNAs (miRNA) occurs commonly in human cancer, but the mechanisms are generally poorly understood. In this study, we examined the contribution of epigenetic mechanisms to miRNA dysregulation in colorectal cancer by carrying out high-resolution ChIP-seq. Specifically, we conducted genome-wide profiling of trimethylated histone H3 lysine 4 (H3K4me3), trimethylated histone H3 lysine 27 (H3K27me3), and dimethylated histone H3 lysine 79 (H3K79me2) in colorectal cancer cell lines. Combining miRNA expression profiles with chromatin signatures enabled us to predict the active promoters of 233 miRNAs encoded in 174 putative primary transcription units. By then comparing miRNA expression and histone modification before and after DNA demethylation, we identified 47 miRNAs encoded in 37 primary transcription units as potential targets of epigenetic silencing. The promoters of 22 transcription units were associated with CpG islands (CGI), all of which were hypermethylated in colorectal cancer cells. DNA demethylation led to increased H3K4me3 marking at silenced miRNA genes, whereas no restoration of H3K79me2 was detected in CGI-methylated miRNA genes. DNA demethylation also led to upregulation of H3K4me3 and H3K27me3 in a number of CGI-methylated miRNA genes. Among the miRNAs we found to be dysregulated, many of which are implicated in human cancer, miR-1-1 was methylated frequently in early and advanced colorectal cancer in which it may act as a tumor suppressor. Our findings offer insight into the association between chromatin signatures and miRNA dysregulation in cancer, and they also suggest that miRNA reexpression may contribute to the effects of epigenetic therapy.

DOI： 10.1158/0008-5472.CAN-11-1076

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Altered expression of microRNA (miRNA) is strongly implicated in cancer, and recent studies have shown that the silencing of some miRNAs is associated with CpG island hypermethylation. To identify epigenetically silenced miRNAs in gastric cancer (GC), we screened for miRNAs induced by treatment with 5-aza-2'-deoxycytidine and 4-phenylbutyrate. We found that miR-34b and miR-34c are epigenetically silenced in GC and that their downregulation is associated with hypermethylation of the neighboring CpG island. Methylation of the miR-34b/c CpG island was frequently observed in GC cell lines (13/13, 100%) but not in normal gastric mucosa from Helicobacter pylori-negative healthy individuals. Transfection of a precursor of miR-34b and miR-34c into GC cells induced growth suppression and dramatically changed the gene expression profile. Methylation of miR-34b/c was found in a majority of primary GC specimens (83/118, 70%). Notably, analysis of non-cancerous gastric mucosae from GC patients (n = 109) and healthy individuals (n = 85) revealed that methylation levels are higher in gastric mucosae from patients with multiple GC than in mucosae from patients with single GC (27.3 versus 20.8%; P < 0.001) or mucosae from H. pylori-positive healthy individuals (27.3 versus 20.7%; P < 0.001). These results suggest that miR-34b and miR-34c are novel tumor suppressors frequently silenced by DNA methylation in GC, that methylation of miR-34b/c is involved in an epigenetic field defect and that the methylation might be a predictive marker of GC risk.

DOI： 10.1093/carcin/bgq203

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Breast cancer arises through the accumulation of multiple genetic alterations and epigenetic changes such as methylation, which silences gene expression in a variety of cancers. In the present study, we applied genomic screening to identify genes upregulated by the demethylating agent 5-aza-2'-deoxycytidine (DAC) in a human breast cancer cell line (MCF7). We identified 288 genes upregulated and 29 genes downregulated more than fivefold after treatment with DAC, and gene ontology analyses revealed the genes to be involved in immune responses, apoptosis, and cell differentiation. In addition, real-time PCR analysis of ten genes silenced in MCF7 cells confirmed that they are upregulated by DAC, while bisulfite-pyrosequencing analysis confirmed that nine of those genes were silenced by methylation. We also found that treating MCF7 cells with DAC restored induction of DFNA5 by p53, as well as by two other p53 family genes, p63gamma and p73beta. Introduction of NTN4 into MCF7 cells suppressed cell growth, indicating that NTN4 has tumor suppressive activity. In primary breast cancers, we detected cancer-specific methylation of NTN4, PGP9.5, and DKK3, suggesting that methylation of these genes could be useful markers for diagnosis of breast cancer. Thus, DNA methylation appears to be a common event in breast cancer, and the genes silenced by methylation could be useful targets for both diagnosis and therapy.

DOI： 10.1007/s10549-009-0600-1

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Interferon regulatory factors (IRFs) are transcription factors known to play key roles in innate and adaptive immune responses, cell growth, apoptosis, and development. Their function in tumorigenesis of gastric cancer remains to be determined, however. In the present study, therefore, we examined epigenetic inactivation of IRF1-9 in a panel of gastric cancer cell lines. We found that expression of IRF4, IRF5, and IRF8 was frequently suppressed in gastric cancer cell lines; that methylation of the three genes correlated with their silencing; and that treating the cells with the demethylating agent 5-aza-2'-deoxycytidine (DAC) restored their expression. Expression of IRF5 in cancer cells was enhanced by the combination of DAC treatment and adenoviral vector-mediated expression of p53, p63, or p73. Interferon-gamma-induced expression of IRF8 was also enhanced by DAC. Moreover, treating gastric cancer cells with DAC enhanced the suppressive effects of interferon-alpha, interferon-beta, and interferon-gamma on cell growth. Among a cohort of 455 gastric cancer and noncancerous gastric tissue samples, methylation of IRF4 was frequently observed in both gastric cancer specimens and noncancerous specimens of gastric mucosa from patients with multiple gastric cancers, which suggests IRF4 methylation could be a useful molecular marker for diagnosing recurrence of gastric cancers. Our findings indicate that epigenetic IRF inactivation plays a key role in tumorigenesis of gastric cancer, and that inhibition of DNA methylation may restore the antitumor activity of interferons through up-regulation of IRFs.

DOI： 10.1111/j.1349-7006.2010.01581.x

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A subset of colorectal cancers (CRCs) show simultaneous methylation of multiple genes; these tumors have the CpG island methylator phenotype (CIMP). CRCs with CIMP show a specific pattern of genetic alterations, including a high frequency of BRAF mutations and a low frequency of p53 mutations. We therefore hypothesized that genes inactivated by DNA methylation are involved in the BRAF- and p53-signaling pathways. Among those, we examined the epigenetic inactivation of insulin-like growth factor-binding protein 7 (IGFBP7) expression in CRCs. We found that in CRC cell lines, the silencing of IGFBP7 expression was correlated with high levels of DNA methylation and low levels of histone H3K4 methylation. Luciferase and chromatin immunoprecipitation assays in unmethylated cells revealed that p53 induces expression of IGFBP7 upon binding to a p53 response element within intron 1 of the gene. Treating methylated CRC cell lines with 5-aza-2'-deoxycytidine restored p53-induced IGFBP7 expression. Levels of IGFBP7 methylation were also significantly higher in primary CRC specimens than in normal colonic tissue (P < 0.001). Methylation of IGFBP7 was correlated with BRAF mutations, an absence of p53 mutations and the presence of CIMP. Thus, epigenetic inactivation of IGFBP7 appears to play a key role in tumorigenesis of CRCs with CIMP by enabling escape from p53-induced senescence.

DOI： 10.1093/carcin/bgp179

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DOI： 10.1016/j.febslet.2009.09.017

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DOI： 10.1074/jbc.M109.043604

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DOI： 10.1016/j.bbalip.2009.01.024

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DOI： 10.1038/sj.jid.5700964

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DOI： 10.1042/BJ20070848

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beta2-Chimaerin, an intracellular receptor for the second messenger diacylglycerol and phorbol esters, is a GTPase-activating protein (GAP) specific for Rac. beta2-Chimaerin negatively controls many Rac-dependent pathophysiological events including tumor development. However, the regulatory mechanism of beta2-chimaerin remains largely unknown. Here we report that beta2-chimaerin is tyrosine-phosphorylated by Src-family kinases (SFKs) upon cell stimulation with epidermal growth factor (EGF). Mutational analysis identified Tyr-21 in the N-terminal regulatory region as a major phosphorylation site. Intriguingly, the addition of SFK inhibitor and the replacement of Tyr-21 with Phe (Y21F) markedly enhanced Rac-GAP activity of beta2-chimaerin in EGF-treated cells. Moreover, the Y21F mutant inhibited integrin-dependent cell spreading, in which Rac1 plays a critical role, more strongly than wild-type beta2-chimaerin. These results suggest Tyr-21 phosphorylation as a novel, SFK-dependent mechanism that negatively regulates beta2-chimaerin Rac-GAP activity.

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DOI： 10.1016/j.bbamcr.2007.05.004

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Diacylglycerol (DAG) kinase (DGK) modulates the balance between the two signaling lipids, DAG and phosphatidic acid (PA), by phosphorylating DAG to yield PA. To date, ten mammalian DGK isozymes have been identified. In addition to the C1 domains (protein kinase C-like zinc finger structures) conserved commonly in all DGKs, these isoforms possess a variety of regulatory domains of known and/or predicted functions, such as a pair of EF-hand motifs, a pleckstrin homology domain, a sterile alpha motif domain and ankyrin repeats. Beyond our expectations, recent studies have revealed that DGK isozymes play pivotal roles in a wide variety of signal transduction pathways conducting development, neural and immune responses, cytoskeleton reorganization and carcinogenesis. Moreover, there has been rapidly growing evidence indicating that individual DGK isoforms exert their specific roles through interactions with unique partner proteins such as protein kinase Cs, Ras guanyl nucleotide-releasing protein, chimaerins and phosphatidylinositol-4-phosphate 5-kinase. Therefore, an emerging paradigm for DGK is that the individual DGK isoforms assembled in their own signaling complexes should carry out spatio-temporally segregated tasks for a wide range of biological processes via regulating local, but not global, concentrations of DAG and/or PA.

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DOI： 10.1016/j.bbalip.2006.12.008

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We investigated the implication of diacylglycerol kinase (DGK) alpha (type I isoform) in melanoma cells because we found that this DGK isoform was expressed in several human melanoma cell lines but not in noncancerous melanocytes. Intriguingly, the overexpression of wild-type (WT) DGKalpha, but not of its kinase-dead (KD) mutant, markedly suppressed tumor necrosis factor (TNF)-alpha-induced apoptosis of AKI human melanoma cells. In the reverse experiment, siRNA-mediated knockdown of DGKalpha significantly enhanced the apoptosis. The overexpression of other type I isoforms (DGKbeta and DGKgamma) had, on the other hand, no detectable effects on the apoptosis. These results indicate that DGKalpha specifically suppresses the TNF-alpha-induced apoptosis through its catalytic action. We found that the overexpression of DGKalpha-WT, but not of DGKalpha-KD, further enhanced the TNF-alpha-stimulated transcriptional activity of an anti-apoptotic factor, NF-kappaB. Conversely, DGKalpha-knockdown considerably inhibited the NF-kappaB activity. Moreover, an NF-kappaB inhibitor blunted the anti-apoptotic effect of DGKalpha overexpression. Together, these results strongly suggest that DGKalpha is a novel positive regulator of NF-kappaB, which suppresses TNF-alpha-induced melanoma cell apoptosis.

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DOI： 10.1016/j.febslet.2007.01.022

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DOI： 10.1093/jb/mvj195

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Diacylglycerol kinases (DGKs) convert diacylglycerol (DG) to phosphatidic acid, and both lipids are known to play important roles in lipid signal transduction. Thereby, DGKs are considered to be a one of the key players in lipid signaling, but its physiological function remains to be solved. In an effort to investigate one of nine subtypes, we found that DGKgamma came to be localized in the nucleus with time in all cell lines tested while seen only in the cytoplasm at the early stage of culture, indicating that DGKgamma is transported from the cytoplasm to the nucleus. The nuclear transportation of DGKgamma didn't necessarily need DGK activity, but its C1 domain was indispensable, suggesting that the C1 domain of DGKgamma acts as a nuclear transport signal. Furthermore, to address the function of DGKgamma in the nucleus, we produced stable cell lines of wild-type DGKgamma and mutants, including kinase negative, and investigated their cell size, growth rate, and cell cycle. The cells expressing the kinase-negative mutant of DGKgamma were larger in size and showed slower growth rate, and the S phase of the cells was extended. These findings implicate that nuclear DGKgamma regulates cell cycle.

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DOI： 10.1074/jbc.M500669200

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：Japanese   Publisher：生命科学系学会合同年次大会運営事務局  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publishing type：Research paper, summary (international conference)  

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：Japanese   Publisher：(公社)日本生化学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：(一社)日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：Japanese   Publisher：日本分子腫瘍マーカー研究会  

Ichushi

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Language：Japanese   Publisher：日本分子腫瘍マーカー研究会  

Ichushi

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Language：Japanese   Publisher：日本分子腫瘍マーカー研究会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

researchmap

Language：English   Publisher：日本癌学会  

Ichushi

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Language：English   Publishing type：Book review, literature introduction, etc.  

Web of Science

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Language：English   Publishing type：Book review, literature introduction, etc.  

DOI： 10.1016/j.bbalip.2007.04.006

Web of Science

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Language：Japanese  

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Language：Japanese  

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Language：English  

DOI： 10.1042/BJ20040681

PubMed

Web of Science

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Language：English  

DOI： 10.1158/0008-5472.CAN-04-0811

Web of Science

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Language：English  

DOI： 10.1074/jbc.M314031200

PubMed

Web of Science

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Language：English  

DOI： 10.1016/S0014-5793(03)00931-1

PubMed

Web of Science

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Language：English  

DOI： 10.1093/oxfordjournals.jbchem.a022652

Web of Science

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Language：English  

DOI： 10.1016/S0009-3084(99)00024-9

PubMed

Web of Science

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Language：Japanese   Publishing type：Book review, literature introduction, etc.  

Web of Science

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Language：English  

DOI： 10.1016/S0005-2760(97)00094-5

Web of Science

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Language：English  

DOI： 10.1093/emboj/16.17.5420

PubMed

Web of Science

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Language：English  

DOI： 10.1074/jbc.272.39.24572

PubMed

Web of Science

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Language：English  

DOI： 10.1016/0929-7855(96)00532-9

PubMed

Web of Science

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Language：English  

DOI： 10.1016/0014-5793(96)00857-5

PubMed

Web of Science

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Language：English  

DOI： 10.1074/jbc.271.31.18931

PubMed

Web of Science

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Language：English  

DOI： 10.1074/jbc.271.14.8394

PubMed

Web of Science

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Language：English  

Web of Science

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Language：English  

DOI： 10.1074/jbc.270.35.20298

PubMed

Web of Science

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Language：English  

Web of Science

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