Biomedical subjects

Fumihiro Kimura

Publications and source records attributed to Fumihiro Kimura.

6 recordsLinked to original sources

PubMed2005

Transformation-associated gene regulation by ATF6alpha during hepatocarcinogenesis.

We have previously reported that the endoplasmic reticulum (ER) stress-regulated transmembrane transcription factor 6 alpha (ATF6alpha) is implicated in the pathogenesis of hepatocellular carcinomas (HCCs). In order to further identify genes that are regulated by ATF6alpha, the global gene expression profiles of the ATF6alpha-transfected and untransfected HCC cell line, HLF, were analyzed. These results were then compared with the differential gene expression patterns of poorly differentiated HCC and control non-tumorous liver tissue. Our findings demonstrate that at least 18 genes are specifically upregulated by ATF6alpha, while another UPR mediator, XBP1 or ER-stress inducer, thapsigargin could partially stimulate or even repress some of them in HCC cells. Moreover, six of these identified genes contain potential ER stress-responsive elements and/or unfolded protein response elements in their 5' regulatory regions.

Activating Transcription Factor 6↗

PubMed2005

[Clinical experience of laparoscopic adrenalectomy: the National Defense Medical College experience].

Twenty-seven laparoscopic adrenalectomies (LapAdx) were performed at the National Defense Medical College between 1999 and 2004. We evaluated the results of LapAdx (group L) compared to the results of open adrenalectomy (group O). Twenty-six of the 27 LapAdx were successfully performed, but one patient with a large pheochromocytoma required open surgey because of arterial bleeding in the renal hilus. The mean operating time in group L (185 +/- 19 min) was not significantly different from that in group O (206 +/- 13 min). The mean estimated blood loss in group L (111 +/- 61 g) was significantly lower than that in group O (308 +/- 67 g). The starting time for oral feeding and for ambulation was significantly earlier in group L than in group O. There was a major complication (intraoperative bleeding) in which a group L patient required a blood transfusion. We also compared the surgical results of 26 patients in LapAdx divided chronologically into the first half and the last half to determine the surgical skill acquired. The operating time was significantly shorter and blood loss significantly less for patients in the last half. In addition, the operating time and blood loss for the first-time LapAdx operators were comparable with those of experienced surgeons. Our results support the efficacy and the minimal invasiveness of LapAdx. The accumulated experience and knowledge regarding laparoscopic surgery in our institute were important in improving surgical procedures and results.

Adrenal Gland Neoplasms↗

PubMed2004

Suppression of clonogenicity by mammalian Dnmt1 mediated by the PCNA-binding domain.

Overexpression of the major DNA methyltransferase Dnmt1 is cytotoxic and has been hypothesized to result in aberrant hypermethylation of genes required for cell survival. Indeed, overexpression of mouse or human Dnmt1 in murine and human cell lines decreased clonogenicity. By frame-shift and deletion constructs, this effect of mouse Dnmt1 was localized at the N-terminal 124 amino acid domain, which mediates interaction with proliferating cell nuclear antigen (PCNA). Mutation of the PCNA-binding site restored normal cloning efficiencies. Overexpression of Dnmt3A or Dnmt3B, which do not interact with PCNA, yielded weaker effects on clonogenicity. Following introduction of the toxic domain, no significant effects on apoptosis, replication, or overall DNA methylation were observed for up to 3 d. Suppression of clonogenicity by Dnmt1 was also observed in cell lines lacking wild-type p53, p21(CIP1), or p16(INK4A). Suppression of clonogenicity by Dnmt1 overexpression may act as a fail-safe mechanism against carcinogenicity of sustained Dnmt1 overexpression.

Animals↗

PubMed2003

Decrease of DNA methyltransferase 1 expression relative to cell proliferation in transitional cell carcinoma.

In many common cancers such as transitional cell carcinoma (TCC), specific genes are hypermethylated, whereas overall DNA methylation is diminished. Genome-wide DNA hypomethylation mostly affects repetitive sequences such as LINE-1 retrotransposons. Methylation of these sequences depends on adequate expression of DNA methyltransferase I (DNMT1) during DNA replication. Therefore, DNMT1 expression relative to proliferation was investigated in TCC cell lines and tissue as well as in renal carcinoma (RCC) cell lines, which also display hypomethylation, as indicated by decreased LINE-1 methylation. Cultured normal uroepithelial cells or normal bladder tissue served as controls. In all tumor cell lines, DNMT1 mRNA as well as protein was decreased relative to the DNA replication factor PCNA, and DNA hypomethylation was present. However, the extents of hypomethylation and DNMT1 downregulation did not correlate. Reporter gene assays showed that the differences in DNMT1 expression between normal and tumor cells were not established at the level of DNMT1 promoter regulation. Diminished DNMT1:PCNA mRNA ratios were also found in 28/45 TCC tissues but did not correlate with the extent of DNA hypomethylation. In addition, expression of the presumed de novo methyltransferases DNMT3A and DNMT3B mRNAs was investigated. DNMT3B overexpression was observed in about half of all high-stage TCC (DNMT3B vs. tumor stage, chi(2): p = 0.03), whereas overexpression of DNMT3A was rarer and less pronounced. Expression of DNMT3A and DNMT3B in most RCC lines was higher than in TCC lines. Our data indicate that DNMT1 expression does not increase adequately with cell proliferation in bladder cancer. This relative downregulation probably contributes to hypomethylation of repetitive DNA but does not determine its extent alone.

Aged↗

PubMed2003

Immunofluorescence analysis of neutrophil nonmuscle myosin heavy chain-A in MYH9 disorders: association of subcellular localization with MYH9 mutations.

The autosomal dominant macrothrombocytopenia with leukocyte inclusions, May-Hegglin anomaly, Sebastian syndrome, and Fechtner syndrome, are rare human disorders characterized by a triad of giant platelets, thrombocytopenia, and characteristic Döhle body-like cytoplasmic inclusions in granulocytes. Epstein syndrome is another autosomal dominant macrothrombocytopenia associated with Alport syndrome but without leukocyte inclusions. These disorders are caused by mutations in the same gene, the MYH9, which encodes the nonmuscle myosin heavy chain-A (NMMHCA). The term, MYH9 disorders, has been proposed, but the clinicopathologic basis of MYH9 mutations has been poorly investigated. In this study, a total of 24 cases with MYH9 disorders and suspected cases were subjected to immunofluorescence analysis by a polyclonal antibody against human platelet NMMHCA. Abnormal subcellular localization of NMMHCA was observed in every neutrophil from individuals with MYH9 mutations. Comparison with May-Grünwald-Giemsa staining revealed that the NMMHCA always coexisted with the neutrophil inclusion bodies, suggesting that NMMHCA is associated with such bodies. In three cases, neutrophil inclusions were not detected on conventional May-Grünwald-Giemsa-stained blood smears but immunofluorescence analysis revealed the abnormal NMMHCA localization. In contrast, cases with Epstein syndrome and the isolated macrothrombocytopenia with normal NMMHCA localization had no MYH9 mutations. An antibody that recognizes the C-terminal 12 mer peptides showed similar immunoreactivity from the patients heterozygous for truncated mutations that abolished the C-terminal epitope, suggesting that normal NMMHCA dimerizes with abnormal NMMHCA to form inclusion bodies. We further propose that the localization pattern can be classified into three groups according to the number, size, and shape of the fluorescence-labeled NMMHCA granule. Immunofluorescence analysis of neutrophil NMMHCA is useful as a screening test for the clear hematopathologic classification of MYH9 disorders.

Case-Control Studies↗

PubMed2003

Activation of Galectin-1 gene in human hepatocellular carcinoma involves methylation-sensitive complex formations at the transcriptional upstream and downstream elements.

The expression of Galectin-1 (Gal-1) mRNA was activated in primary hepatocellular carcinomas (HCCs) compared to matched non-tumorous liver tissues. To elucidate the mechanism of Gal-1 activation in HCC cells, DNA methylation encompassing the transcriptional start site (-165/+151) was examined. Among 12 CpG dinucleotides on both DNA strands, those at positions -116, -109, -52, -41, -36, +35 and +43 were preferentially methylated in non-tumorous liver tissue, while hypomethylated in the matched HCC tissue. Transient transfection of a series of deleted GAL-1 promoters revealed that both an upstream (-57/-31) and a downstream (+10/+57) elements accounted for efficient promoter activity. Electrophoretic mobility shift assay of the upstream element (-63/-30) using nuclear extracts from three HCC cell lines (HLF, HuH7 and HepG2) and normal liver cells revealed at least two complexes (alpha and (beta) interacted with the upstream element in all of the nuclear extracts. Competition experiments revealed that the complex beta preferentially attached to the upstream element harboring unmethylated CpGs. On the other hand, at least three complexes (I, II and III) interacted with the downstream element in all of the nuclear extracts. Competition experiments revealed that complex I specifically attached to the downstream element harboring unmethylated CpG at +35. Furthermore, a DNase I protection assay revealed that a methylation-associated conformational alteration occurred near the CpG site at +35 in HLF cells. Thus, the specific interaction of methylation-sensitive factors to the upstream and downstream elements may be essential for the activation of the Gal-1 gene in HCC cells.

Base Sequence↗