Publications by authors named "Keizou Ookawa"

Recently, Nishihira et al. demonstrated the presence of two types of TDP-43 pathology in sporadic amyotrophic lateral sclerosis (ALS) (Acta Neuropathol 2008; 116: 169-182). Type 1 represents the TDP-43 distribution pattern observed in classic ALS, whereas type 2 shows the presence of TDP-43 inclusions in the frontotemporal cortex, hippocampal formation, neostriatum and substantia nigra and is significantly associated with dementia.

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Irinotecan hydrochloride (CPT-11) is an effective anticancer drug, and its metabolic pathway has been well studied. Nevertheless, in human hepatocellular carcinoma (HCC), its cytotoxicity is less well studied and the determination of its chemosensitivity is unclear. We, therefore, examined chemosensitivities of HCC cell lines for CPT-11 and SN-38, and mRNA expressions of several molecules in their metabolic pathway.

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The study of epithelial differentiation touches upon many modern aspects of biology. The epithelium is in constant dialogue with the underlying mesenchyme to control stem cell activity, proliferation in transit-amplifying compartments, lineage commitment, terminal differentiation and, ultimately, cell death. There are spatially distinct compartments dedicated to each of these events.

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Retinoblastoma gene product (pRB) plays critical roles in regulation of the cell cycle and tumor suppression. It is known that downregulation of pRB can stimulate carcinogenesis via abrogation of the pRB pathway, although the mechanism has not been elucidated. In this study, we found that Mdm2, a ubiquitin ligase for p53, promoted ubiquitin-dependent degradation of pRB.

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The effects of 6-ethoxyzolamide (ETZ), a carbonic anhydrase (CA) inhibitor, on differentiation of the mouse preadipocyte cell line 3T3-L1 were examined by quantitative image analysis of intracellular fat storage. For adipocyte differentiation, postconfluent cells were treated with a ligand of the peroxisome proliferator-activated receptor gamma (PPARgamma), troglitazone (TRG), and dexamethasone for 2 days. Differentiated cells showed weak fat staining at day 4 which increased thereafter, correlating with CAIII expression.

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Since ethacrynic acid (EA), an SH modifier as well as glutathione S-transferase (GST) inhibitor, has been suggested to induce apoptosis in some cell lines, its effects on a human colon cancer cell line DLD-1 were examined. EA enhanced cell proliferation at 20-40 microM, while it caused cell death at 60-100 microM. Caspase inhibitors did not block cell death and DNA ladder formation was not detected.

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p53-mediated induction of p21(WAF1), a cyclin-dependent protein kinase inhibitor, is known to protect cancer cells from the cytotoxic effects of anti-cancer drugs or gamma-irradiation. Since the p53 gene is frequently inactivated in cancer cells, we examined whether p21(WAF1) expression may alter the sensitivity of cancer cells with mutated p53 gene to anti-cancer drugs. Cells of a colon cancer cell line DLD-1 were transfected with p21(WAF1) expression vector controlled by a tetracycline-repressable promoter and transfectants were cloned (Dp21-1).

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MUC2 is one of the major components of mucins that provide a protective barrier between epithelial surfaces and the gut lumen. We investigated possible alterations of MUC2 gene expression by p53 and p21(Sdi1/Waf1/Cip1) in a human colon cancer cell line, DLD-1, establishing subclones in which a tetracycline-regulatable promoter controls exogenous p53 and p21 expression. MUC2 mRNA more significantly increased in response to p53 than to p21.

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Whether single cells immunohistochemically positive for glutathione S-transferase P1-1 (GSTP1-1) induced in the female mouse liver by DEN (Hatayama et al., Carcinogenesis, 14, 537-538, 1993) are precursor initiated cells of preneoplastic foci, is of importance in chemical hepatocarcinogenesis. Nrf2 transactivates a wide variety of ARE (anti-oxidant response element)-mediated enzymes including GSTP1-1.

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Bacterial lipopolysaccharides (LPS) induce expression of multiple genes in endothelial cells, which are critical cellular effectors in various pathologic syndromes. Using subtractive hybridization to identify genes that are differentially induced in human endothelial cells treated with LPS, we found that retinoic acid-inducible gene I (RIG-I) is induced in endothelial cells stimulated with LPS. RIG-I encodes a protein belonging to the DExH-box family which has diverse roles in regulation of gene expression and cellular functions.

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