Hisaki Nagai

SOCS1 Is a Suppressor of Liver Fibrosis and Hepatitis-induced Carcinogenesis

Hepatocellular carcinomas (HCCs) mainly develop from liver cirrhosis and severe liver fibrosis that are established with long-lasting inflammation of the liver. Silencing of the suppressor of the cytokine signaling-1 (SOCS1) gene, a negative regulator of cytokine signaling, by DNA methylation has been implicated in development or progress of HCC. However, how SOCS1 contributes to HCC is unknown. We examined SOCS1 gene methylation in >200 patients with chronic liver disease and found that the severity of liver fibrosis is strongly correlated with SOCS1 gene methylation. In murine liver fibrosis models using dimethylnitrosamine, mice with haploinsufficiency of the SOCS1 gene (SOCS1−/+ mice) developed more severe liver fibrosis than did wild-type littermates (SOCS1+/+ mice). Moreover, carcinogen-induced HCC development was also enhanced by heterozygous deletion of the SOCS1 gene. These findings suggest that SOCS1 contributes to protection against hepatic injury and fibrosis, and may also protect against hepatocarcinogenesis.

Amplification, up‐regulation and over‐expression of DVL‐1, the human counterpart of the Drosophila disheveled gene, in primary breast cancers

Wnt proteins form a family of highly conserved, secreted signaling molecules that regulate cell‐to‐cell interactions during embryogenesis. Wnt genes and Wnt signaling are also implicated in cancer. It has been shown that Wnt proteins bind to receptors of the frizzled family on the cell surface. Through several cytoplasmic relay components including DVL‐1, the human counterpart of the Drosophila disheveled gene, the signal is transduced to β‐catenin, which then enters the nucleus and forms a complex with T‐cell factor (TCP) to activate transcription of Wnt target genes. We describe here the amplification of DVL‐1 in 13 of 24 primary breast cancers examined, and increased expression of this gene in 11 of those tumors in comparison to corresponding non‐cancerous breast tissues. Immunohistochemical staining demonstrated that DVL‐1 protein was prominent in the cytoplasm of cancer cells, but not in normal epithelial cells of the mammary duct or in myoepithelial cells. These data indicate that amplification and increased expression of the DVL‐1 gene may play some role in human breast carcinogenesis through derangement of the Wnt signaling pathway.

Upregulation and Overexpression of Human X-box Binding Protein 1 (hXBP-1) Gene in Primary Breast Cancers

BackgroundHuman X-box binding protein 1 (hXBP-1) is a transcription factor essential for hepatocyte growth as well as for plasma cell differentiation. hXBP-1 also binds to cis-elements of human T cell leukemia virus and human major histocompatibility complex genes. In order to clarify the role of XBP-1 in breast cancer, here we investigated the expression of XBP-1 in 11 primary breast cancers and 5 breast cancer cell lines.Materials and MethodsThe study population consisted of eleven patients who were underwent surgery for breast cancer from 2000 to 2002. Five breast cancer cell lines (MDA-MB-453, CRL1500, YMB-1-E, MCF7 and HBL100) were analyzed for XBP-1 expression. Reverse transcription Polymerase chain reaction was performed on 6 primary breast cancers. Then we investigated XBP-1 expression by immunohistochemically on archived paraffin-embedded sections.ResultshXBP-1 mRNA expression was increased in all 11 primary breast cancers we examined, as well as 5 breast cancer cell lines, but hardly detectable in non-cancerous breast tissue. Immunohistochemical staining demonstrated that hXBP-1 protein stained strongly in the cytoplasm of cancer cells but was unreactive in the normal breast ductal epithelial and myoepithelial cells.ConclusionsThese data indicate that increased expression of the hXBP-1 gene may play some role in human breast carcinogenesis through impairment of cell differentiation regulation.

Suppressor of cytokine signalling-1 gene silencing in acute myeloid leukaemia and human haematopoietic cell lines.

The aim of this study was to investigate whether the suppressor of cytokine signalling (SOCS)‐1 can act as a tumour suppressor when functioning as a negative regulator of the Janus family tyrosine kinases (JAKs), which have been reported to play important roles in leukaemogenesis. For this purpose, we carried out molecular analysis of the SOCS‐1 gene in human acute myeloid leukaemia (AML) and human haematopoietic cell lines. Sequencing alterations in the coding region were found in two of 90 primary AML samples and one of 17 cell lines. Hypermethylation of the SOCS‐1 gene was also observed in 72% of primary cases and 52% of cell lines and aberrant methylation strongly correlated with reduced expression. Transfection of SOCS‐1 into Jurkat cells harbouring the mutation and methylation suppressed cell growth at a low serum concentration. These findings indicate that SOCS‐1 is frequently silenced in haematopoietic malignancies, mainly as a result of hypermethylation, and suggest that SOCS‐1 may be able to function as a tumour suppressor.

Thermoelectric properties of (Zn1−yMgy)1−xAlxO ceramics prepared by the polymerized complex method

(Zn1−yMgy)1−xAlxO powders were synthesized by the polymerized complex method and then consolidated by spark plasma sintering apparatus. The microscopic structure and thermoelectric properties were examined comparing with the experimental results of the samples prepared by the conventional solid-state reaction method. A small amount of ZnAl2O4 spinel phase as the second phase was observed in the sintered samples with x⩾0.02 by x-ray diffraction and a scanning electron microscope. The grain size of the samples prepared by the polymerized complex method is much smaller than that of the samples prepared by the conventional solid-state reaction method. The absolute values of the Seebeck coefficient and electrical resistivity decrease with increasing x up to about x=0.01, but above x=0.01 they are almost independent of x. This result indicates that the solubility limit of Al in Zn1−xAlxO is about x=0.01, which is also confirmed by 27Al nuclear magnetic resonance spectroscopy. At a fixed composition of x, the ab...

Hypermethylation associated with inactivation of the SOCS-1 gene, a JAK/STAT inhibitor, in human hepatoblastomas

AbstractWe recently demonstrated inactivation in hepatocellular carcinomas (HCCs) of the gene encoding SOCS1/JAB1/SSI-1, a JAK-binding protein that regulates the JAK/STAT signal-transduction pathway. In a follow-up immunochemical investigation of expression of SOCS-1 in hepatoblastomas (HBLs), the protein was markedly reduced in half of the HBL tumors we examined. CpG-rich regions upstream of the SOCS-1 gene were hypermehylated in 7 of the 15 HBL cases. The results suggest that hypermethylation may play an important role in silencing the SOCS-1 gene, not only in adult HCCs, but also in liver tumors arising in childhood.

Inactivation of both alleles of the DPC4/SMAD4 gene in advanced colorectal cancers: identification of seven novel somatic mutations in tumors from Japanese patients

Loss of heterozygosity (LOH) of loci on chromosome 18q occurs in a majority of colorectal cancers. The DPC4/SMAD4 gene, lying in close proximity to the DCC gene at 18q21.1, was recently identified as a candidate tumor suppressor for the genesis of pancreatic cancer as well as a predisposing gene for Juvenile Polyposis Syndrome (JPS). The gene product functions as a cytoplasmic mediator in the signaling pathway of transforming growth factor beta (TGF-beta). To investigate the potential role of DPC4/SMAD4 gene in colorectal cancers, we examined 73 tumors of clinical stages II or III from Japanese patients, for LOH at 18q21 and also for subtle mutations anywhere within the coding region of DPC4/SMAD4. LOH was identified in 50 (78%) of the 64 tumors that were informative for polymorphic markers in the region. Somatic mutations were identified in seven of those tumors: two frameshift mutations, a 1-bp deletion (326 del T) in exon 8 and a 1-bp insertion (50-51 ins A) in exon 1; two nonsense mutations, Arg445Ter in exon 10 and Glu538Ter in exon 11; and three missense mutations, Asn129Lys in exon 2, Tyr95Asn in exon 2, and Asp355Glu in exon 8. Three of the seven mutations were observed in the mad homology 1 (MH1) domain encoded by exons 1 and 2. In all of the tumors carrying intragenic mutations of one allele, LOH analysis had shown that the other allele was missing. The results demonstrated that inactivation of both alleles of the DPC4/SMAD4 gene occurs in a substantial proportion of advanced colorectal cancers, and that the DPC4/SMAD4 gene probably exerts a tumor-suppressor effect for colorectal carcinogenesis that fulfills the criterion of the two-hit concept proposed by Knudson [A.G. Knudson, Hereditary cancer, oncogenes, and anti-oncogenes, Cancer Res. 45 (1985) 1437-1443.].

The c-Jun NH2-terminal kinase3 (JNK3) gene: genomic structure, chromosomal assignment, and loss of expression in brain tumors.

AbstractBy examining 19 human cell lines derived from brain tumors for altered expression of expressed sequence tags (ESTs) in chromosomal band 4q21–22, we detected loss of expression, in 10 cell lines, of two sequences, WI6336 and WI7913. Both corresponded to the c-Jun NH2-terminal kinase (JNK) 3. In the present study, genomic cloning revealed that the JNK3 gene consists of 14 exons interrupted by 13 introns; its transcription-initiation site is within exon 3 and the termination codon lies in exon 14. Fluorescence in situ hybridization (FISH) and radiation-hybrid mapping confirmed the gene to 4q21–22. Together with prior evidence that, in JNK3-deficient mice, the JNK3 signaling pathway mediates apoptosis in central nervous tissue, our results suggest that loss of expression of the JNK3 gene may play an important role in the development of brain tumors in humans.

Thermoelectric properties of CoSb3 with dispersed FeSb2 particles

We have prepared a sintered CoSb3–FeSb2 composite where the FeSb2 particles are dispersed in the CoSb3 matrix by mechanical grinding (MG) and hot pressing, and investigated the Seebeck coefficient, electrical resistivity, and thermal conductivity in order to estimate the corresponding figure of merit. The thermal conductivity of the composite is lower than that of CoSb3. The electrical resistivity of the composite increases with increasing MG time, but it is lower than that of CoSb3 at high temperature. The decrease in the thermal conductivity and the lesser increase in the electrical resistivity are ascribed to the enhancement of phonon scattering caused by the dispersion of FeSb2 particles in the CoSb3 matrix and the low electrical resistivity of FeSb2, respectively. As a result, the composite whose molar ratio of CoSb3 to FeSb2 is 0.7:0.3 and the MG time is 25 h has a maximum figure of merit value of 6.1×10−4 K−1 at 756 K. This value is much larger than the maximum value of CoSb3 at 482 K of 3.2×10−4 K−1.

Identification of a 1-cM Region of Common Deletion on 4q35 Associated With Progression of Hepatocellular Carcinoma

To identify the location of one or more of the putative tumor suppressor genes (TSG) on chromosome arm 4q that may be involved in hepatocellular carcinoma (HCC), we examined 96 primary HCCs for their patterns of allelic loss at 39 microsatellite marker loci distributed along this chromosome arm. Allelic loss at one or more loci was observed in 71 (74%) HCCs. Detailed deletion mapping identified two distinct commonly deleted regions; one was located within a 1‐cM interval flanked by D4S1534 and D4S2929 at 4q21–22, the other in the 1‐cM interval flanked by D4S2921 and D4S2930 at 4q35. Of the tumors for which clinical data were available, allelic loss at 4q35 was more frequent in poorly or moderately differentiated tumors than in well‐differentiated tumors (3/15, 20%, vs. 14/21, 67%, P = 0.008); in tumors larger than 2 cm in size (2/11, 18%, vs. 34/62, 55%, P = 0.046); and in tumors that arose from liver cirrhosis as opposed to HCCs arising from chronic hepatitis (25/42, 60%, vs. 9/27, 33%, P = 0.048). The association of allelic losses on 4q35 with larger tumor size and aggressive histological type implies that loss or inactivation of TSG located within the 1‐cM interval of 4q35 identified here contribute to progression of HCCs. Genes Chromosomes Cancer 25:284–289, 1999.