[Show abstract][Hide abstract] ABSTRACT: To identify genetic variants that confer the risk of Graves' disease (GD) in the Japanese population, we conducted a two-stage genome-wide association study (GWAS) using 1119 Japanese individuals with GD and 2718 unrelated controls, and a subsequent replication study using independent 432 GD cases and 1157 controls. We identified 34 single nucleotide polymorphisms (SNPs) to be significantly associated with GD in the GWAS phase. Twenty-two out of 34 SNPs remained positive in the replication study. All 22 SNPs were located within the major histocompatibility complex (MHC) locus on chromosome 6p21. No strong long-range linkage disequilibrium (LD) was observed among the 22 SNPs, indicating independent involvement of multiple loci within the MHC with the risk of GD. Multivariate stepwise logistic regression analysis selected rs3893464, rs4313034, rs3132613, rs4248154, rs2273017, rs9394159 and rs4713693, as markers for independent risk loci for GD. The analysis of LD between these seven SNPs and tagging SNPs for GD-associated human leukocyte antigen (HLA) alleles in the Japanese population (HLA-DPB1(*)0501 and HLA-A(*)0206) demonstrated that all of and five of seven SNPs were not in strong LD with HLA-DPB1(*)0501 and HLA-A(*)0206, respectively. Although causal variants remain to be identified, our results demonstrate the existence of multiple GD susceptibility loci within the MHC region.
Full-text · Article · Sep 2011 · Journal of Human Genetics
[Show abstract][Hide abstract] ABSTRACT: Oncogenic KRAS plays several key roles in a three-dimensional (3D) colonic-crypt model. However, miRNA expression regulated by oncogenic KRAS in this model is still elusive.
The differential expression of 105 cancer-related microRNAs was examined and compared in HCT116 cells and HKe3 cells (HCT116 cells in which mutated KRAS allele was deleted) in 3D culture. HKe3 cells stably overexpressing oncogenic KRAS and the public datasets for microRNA expression analysis of colorectal cancer were further examined.
The increased expression of miR-200c, miR-221 and miR-222 were observed exclusively in 3D culture, but not in the two-dimensional culture. These microRNAs were regulated by oncogenic KRAS and were significantly overexpressed in human colorectal tumor specimens. Of note, the protein expression level of Phosphatase and tensin homolog (PTEN), a putative target of miR-221/222 cluster, was reduced under the control of oncogenic KRAS in a 3D-specific manner.
Oncogenic KRAS regulates 3D-specific molecules, possibly being associated with colorectal tumor development in vivo.
Full-text · Article · Jul 2011 · Anticancer research
[Show abstract][Hide abstract] ABSTRACT: We previously investigated the mRNA expression of colorectal cancer cell lines via a microarray analysis and found several genes that were significantly up-regulated by oncogenic KRAS under serum-starved conditions. Of these genes, we focused on ribonucleotide reductase M2 (RRM2), which was reported to be associated with DNA synthesis.
Cell proliferation and colony formation assays were performed using HCT116 cells transfected with lentiviral RRM2-shRNAs.
Under serum-starved conditions, the expression level of RRM2 protein increased in HCT116 cells compared to HKe3 cells (HCT116 cells with a disruption in oncogenic KRAS), and the re-expression of KRAS in HKe3 cells induced the expression of RRM2. Both the cell proliferation under serum-depleted conditions and the anchorage-independent growth were impaired by the reduction of RRM2 protein expression.
RRM2 represents a novel therapeutic target, thus highlighting the potential utility of RRM2 inhibitors in colorectal cancer with oncogenic KRAS.
Full-text · Article · Jul 2011 · Anticancer research
[Show abstract][Hide abstract] ABSTRACT: ZFAT was originally identified as an immune-related transcriptional regulator containing 18 C2H2-type zinc-finger domains and one AT-hook. ZFAT is highly conserved among species and functions as an anti-apoptotic molecule in the lymphoblastic leukemia cell line, MOLT-4. We recently demonstrated that ZFAT is an essential molecule for hematopoietic differentiation in blood islands through the direct regulation of particular transcriptional factors, including Tal1, for endothelial cell assembly, and for the branch point formation of capillary-like structures. However, the molecular mechanisms underlying the anti-apoptotic function of ZFAT remain unknown. Here, we report that ZFAT knockdown by small interfering RNA induced apoptosis in mouse embryonic fibroblasts (MEFs). This response had been similarly observed for MOLT-4 cells. To explore the molecular mechanisms for ZFAT in anti-apoptotic function in both MEFs and MOLT-4 cells, microarray expression analysis and quantitative RT-PCR were done. Of interest was that Bcl-2 and Il6st were identified as commonly down-regulated genes by the depletion of ZFAT for both MEFs and MOLT-4 cells. These results suggest that ZFAT is a critical molecule for cell survival in MEFs and MOLT-4 cells at least in part through the regulation of the apoptosis involved in the BCL-2- and IL6st-mediated pathways. Further elucidation of the molecular functions for ZFAT might shed light on the cellular programs in the mesoderm-derived cells.
No preview · Article · Mar 2011 · Cellular & Molecular Biology Letters
[Show abstract][Hide abstract] ABSTRACT: ZFAT, originally identified as a susceptibility gene for autoimmune thyroid disease, encodes a transcriptional regulator with one AT-hook and 18 C(2)H(2)-type zinc-finger domains. It is highly conserved among species. Here, we demonstrate that ZFAT is clearly expressed in human umbilical vein endothelial cells (HUVECs). Furthermore, we show that endothelial cell assembly and the branch point formation of capillary-like structures in HUVECs is impaired by the reduction of ZFAT expression through the use of ZFAT-miRNAs, whereas differences in cell proliferation or apoptotic features were not observed after the reduction in ZFAT expression. These results suggest that ZFAT may have critical roles in the capillary-like network formation that is involved in vascular remodeling. Elucidating the ZFAT-mediated transcriptional network will lead to a better understanding of the molecular mechanisms of angiogenesis.
[Show abstract][Hide abstract] ABSTRACT: TAL1 plays pivotal roles in vascular and hematopoietic developments through the complex with LMO2 and GATA1. Hemangioblasts, which have a differentiation potential for both endothelial and hematopoietic lineages, arise in the primitive streak and migrate into the yolk sac to form blood islands, where primitive hematopoiesis occurs. ZFAT (a zinc-finger gene in autoimmune thyroid disease susceptibility region/an immune-related transcriptional regulator containing 18 C(2)H(2)-type zinc-finger domains and one AT-hook) was originally identified as an immune-related transcriptional regulator containing 18 C(2)H(2)-type zinc-finger domains and one AT-hook, and is highly conserved among species. ZFAT is thought to be a critical transcription factor involved in immune-regulation and apoptosis; however, developmental roles for ZFAT remain unknown. Here we show that Zfat-deficient (Zfat(-/-)) mice are embryonic-lethal, with impaired differentiation of hematopoietic progenitor cells in blood islands, where ZFAT is exactly expressed. Expression levels of Tal1, Lmo2, and Gata1 in Zfat(-/-) yolk sacs are much reduced compared with those of wild-type mice, and ChIP-PCR analysis revealed that ZFAT binds promoter regions for these genes in vivo. Furthermore, profound reduction in TAL1, LMO2, and GATA1 protein expressions are observed in Zfat(-/-) blood islands. Taken together, these results suggest that ZFAT is indispensable for mouse embryonic development and functions as a critical transcription factor for primitive hematopoiesis through direct-regulation of Tal1, Lmo2, and Gata1. Elucidation of ZFAT functions in hematopoiesis might lead to a better understanding of transcriptional networks in differentiation and cellular programs of hematopoietic lineage and provide useful information for applied medicine in stem cell therapy.
Full-text · Article · Aug 2010 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: Growth and differentiation of colonic epithelium are regulated in the three-dimensional (3D) physiological architecture, colonic crypt, and deregulation of 3D interactions is involved in tumorigenesis. Cell-based 3D culture systems provide a suitable approach bridging the gap between two-dimensional (2D) culture and animal models. KRAS mutations are found at high frequencies in human colorectal cancer (CRC); however, KRAS-targeted cancer therapy has not been developed. Here, we have established a 3D cell culture model resembling the colonic crypt by use of HKe3 cells, human CRC HCT116 cells disrupted at activated KRAS. In this 3D colonic crypt model, HKe3 cells showed the features of time course-dependent transit-amplifying and terminal-differentiated stages, which are characteristic of normal colonic crypt. On the basis of the features of HCT116 cells, activated KRAS inhibited normal cell polarity and apoptosis in 3D culture. The expression of DNA repair-related tumor suppressor genes including TP53, BRCA1, BRCA2, and EXO-1 was markedly suppressed by activated KRAS in 3D culture but not in 2D culture. These results together suggest that activated KRAS plays critical roles in the accumulation of genetic alterations through inhibition of DNA repair genes and apoptosis and that this 3D culture model will provide a useful tool for investigating the molecular mechanisms of CRC development.
Full-text · Article · May 2010 · Neoplasia (New York, N.Y.)
[Show abstract][Hide abstract] ABSTRACT: Three-dimensional culture (3DC) is a relevant in vitro model used to study prostate development and carcinogenesis. Recent studies have indicated that 3DC-associated genes would be more sensitive as prognostic markers for cancer; however, no 3DC-associated genes in prostate cancer (CaP) have thus far been elucidated.
Candidate 3DC-associated genes in non-malignant prostatic epithelial cells, RWPE-1 and TA2, were selected, based on a comparison of microarray gene expression data between cells grown in two-dimensional culture (2DC) and in 3DC. To extract CaP-associated genes among the 3DC-associated genes, gene expression levels from the microdissected tissue samples were compared between 20 well-differentiated or 20 poorly differentiated CaP, as well as matched normal prostate epithelium. The expression levels of CaP-associated genes in 3DC were validated by quantitative RT-PCR using TA2 cells in 2DC and 3DC. Protein expression of periostin (POSTN), which is one of the 3DC CaP-associated genes, was further evaluated in the clinical samples by immunohistochemistry.
Several genes including POSTN were identified as CaP-associated genes using a 3DC system. Immunohistochemical analyses revealed that POSTN expression was increased in the early stages of CaP (Gleason score 6-7), but not in the advanced stages of CaP. Furthermore, the positive ratio observed for the expression of POSTN in tumor-associated stroma was significantly correlated with the degree of malignancy.
POSTN, one of the 3DC-associated genes, may serve as a potential biomarker for predicting the pathological grade and prognosis of CaP. Prostate 69: 1398-1403, 2009. (c) 2009 Wiley-Liss, Inc.
[Show abstract][Hide abstract] ABSTRACT: ZFAT (also known as ZNF406), originally identified as a candidate gene for autoimmune thyroid disease, encodes a zinc-finger protein, however, its function has not been elucidated. Here, we report that human ZFAT protein is expressed in peripheral B and T lymphocytes and a human acute T lymphoblastic leukaemia cell line, MOLT-4 cells. Intriguing is that mouse ZFAT expression in CD4(+) lymphocytes is increased during blast formation. Furthermore, ZFAT-knockdown in MOLT-4 induces apoptosis via activation of caspases. These results suggested that ZFAT protein is a critical regulator involved in apoptosis and cell survival for immune-related cells.
[Show abstract][Hide abstract] ABSTRACT: The human ZFAT gene encodes a 1243-amino-acid protein containing one AT hook and 18 C2H2 zinc finger domains, which are highly conserved among ZFAT orthologues from fish to mammalian species. Consistent with the presence of multiple predicted nuclear localization signals, endogenous ZFAT protein was found to be localized to the nucleus. In the mouse tissues examined by Western blotting, ZFAT was found to be expressed in thymus, spleen, and lymph nodes, but not in other tissues, including bone marrow. Furthermore, ZFAT protein was found to be up-regulated during the transition from CD4(-)CD8(-) to CD4(+)CD8(+) thymocytes and to be expressed only in B and T lymphocytes in peripheral lymphoid tissues. Expression array analyses demonstrated that genes that are down-regulated upon ZFAT overexpression in mouse Ba/F3 cells are significantly enriched for those functionally related to immune responses. These results suggest that ZFAT functions as a critical transcriptional regulator in B and T lymphocytes.