Biomedical subjects

Naoki Watanabe

Publications and source records attributed to Naoki Watanabe.

At least 37 records · Page 2Linked to original sources

PubMed2005

Survivin enhances telomerase activity via up-regulation of specificity protein 1- and c-Myc-mediated human telomerase reverse transcriptase gene transcription.

Suppression of apoptosis is thought to contribute to carcinogenesis. Survivin, a member of the inhibitor-of-apoptosis family, blocks apoptotic signaling activated by various cellular stresses. Since elevated expression of survivin observed in human cancers of varied origin was associated with poor patient survival, survivin has attracted growing attention as a potential target for cancer treatment. Immortalization of cells also is required for carcinogenesis; telomere length maintenance by telomerase is required for cancer cells to proliferate indefinitely. Yet how cancer cells activate telomerase remains unclear. We therefore examined possible interrelationships between survivin expression and telomerase activity. Correlation between survivin and human telomerase reverse transcriptase (hTERT) expression was observed in colon cancer tissues, and overexpression of survivin enhanced telomerase activity by up-regulation of hTERT expression in LS180 human colon cancer cells. DNA-binding activities of specificity protein 1 (Sp1) and c-Myc to the hTERT core promoter were increased in survivin gene transfectant cells. Phosphorylation of Sp1 and c-Myc at serine and threonine residues was enhanced by survivin, while total amounts of these proteins were unchanged. Further, "knockdown" of survivin by a small inhibitory RNA decreased Sp1 and c-Myc phosphorylation. Thus survivin participates not only in inhibition of apoptosis, but also in prolonging cellular lifespan.

Chromones↗

PubMed2005

Beclin 1 augmented cis-diamminedichloroplatinum induced apoptosis via enhancing caspase-9 activity.

Beclin 1, identified as a Bcl-2-interacting protein, is known to enhance autophagy. However, the effect of Beclin 1 on apoptotic signaling has remained unclear. Here, we show that overexpression of Beclin 1 in MKN28 human gastric cancer cells augmented cis-diamminedichloroplatinum (CDDP)-induced apoptosis. Conversely, "knockdown" of Beclin 1 by a small inhibitory RNA in MKN 1 cells attenuated this cytotoxicity. Furthermore, not only caspase-3/7 activities, but also caspase-9 activity was increased in Beclin 1 gene transfectants treated with CDDP, and caspase-9 inhibitor completely abolished augmentation of CDDP-induced apoptosis by Beclin 1 as did a caspase-3 inhibitor. Thus, Beclin 1 augments CDDP-induced apoptosis through enhancing caspase-9 activity and functions as a pro-apoptotic molecule.

Antineoplastic Agents↗

PubMed2005

Detection of autoantibodies to livin and survivin in Sera from lung cancer patients.

Survivin and livin are highly expressed in cancer cells and transformed cells, but show little or no expression in normal differentiated tissues. Although human antibody responses to cancer-associated antigens have been detected, the response to livin has not yet been described in lung cancer patients. We examined prevalence of anti-livin antibodies in such patients with a specific enzyme-linked immunosorbent assay (ELISA) using recombinant protein. Using a cutoff value for positivity determined as the mean absorbance +2S.D. for healthy control samples, 19 of 37 lung cancer patients (51.3%) were positive for anti-livin antibodies. Of 31 samples from the same lung cancer patients, 18 (58.1%) were positive for anti-survivin antibodies. When sera from 31 lung cancer patients were assessed simultaneously by anti-survivin and anti-livin ELISAs. Twenty-one patients (71%) were positive for survivin, livin, or both. Intensity of anti-livin antibody responses did not correlate with intensity of anti-survivin responses. Like anti-survivin antibodies, anti-livin antibodies, thus, can be detected in many lung cancer patients. Testing for both antibodies together may prove useful in detecting lung cancer, but more extensive studies are needed to establish the clinical significance of anti-livin antibodies.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Autoantibodies to survivin in patients with chronic hepatitis and hepatocellular carcinoma.

OBJECTIVES: Autoantibodies to tumor-associated antigens including survivin have been detected in sera from patients with hepatocellular carcinoma (HCC). However, little is known about autoantibody responses to tumor-associated antigens in patients with chronic hepatitis, which strongly predisposes to development of HCC. METHODS: We subjected sera from 57 patients with chronic hepatitis and 29 patients with HCC to an enzyme-linked immunosorbent assay (ELISA) using a full-length recombinant survivin protein. A cutoff value for positivity was determined as the mean absorbance +2SD for sera from healthy volunteers. RESULTS: In patients with chronic viral hepatitis, elevated anti-survivin antibodies were detected in 10 of 57 sera (17.5%); in HCC patients, such elevation were detected in 7 of 29 sera (24.1%). The levels of anti-survivin antibodies in HCC patients with HCV infection were significantly higher than those in the healthy control and HCC patients with HBV infection. However, there were no significant differences in the levels of anti-survivin antibodies between HCV and HCC patients with HCV infection. CONCLUSIONS: We demonstrated that elevated anti-survivin antibodies were detected for the first time in patients with chronic viral hepatitis. The results suggest that the levels of anti-survivin antibodies have no association with the progression of HCV or HBV to HCC.

Autoantibodies↗

PubMed2005

Analysis of the prevalence of tetracycline resistance genes in clinical isolates of Enterococcus faecalis and Enterococcus faecium in a Japanese hospital.

Prevalence of seven tetracycline resistance (TC(R)) genes--tet(L), tet(M), tet(K), tet(O), tet(S), tet(T), and tet(U)--which are known to be distributed to gram-positive cocci was analyzed for 224 Enterococcus faecalis and 46 Enterococcus faecium clinical isolates obtained in a Japanese hospital. Any of the TC(R) genes was detected in 75.9% of all the enterococcal strains. The tet(M) was detected at highest rates in both E. faecalis (75.0%) and E. faecium (69.6%), followed by tet(L), which was harbored in 6.7% of E. faecalis isolates and 30.4% of E. faecium isolates. The tet(O), tet(S), and tet(T) were detected in E. faecalis at low frequencies mostly associated with tet(M), while tet(K) and tet(U) were not detected. Nucleotide sequences of tet(S) from E. faecalis strains were identical to that reported in Listeria monocytogenes. Sequences of tet(O) from two E. faecalis strains were almost identical to each other and also to those from Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus mutans, Campylobacter jejuni, and Campylobacter coli, although minor sequence divergence was observed. The tet(T), which had been reported only in Streptococcus pyogenes, was found in five E. faecalis strains. Sequence of the enterococcal tet(T) differed from that of S. pyogenes by only four nucleotides (four amino acids) and showed high sequence identity (99.8%, amino acid level). Enterococcal strains with any one TC(R) gene or those with two TC(R) genes showed generally similar MICs of tetracyclines, and no evident difference in resistance level was observed.

Amino Acid Sequence↗

PubMed2005

Detection of a novel aph(2") allele (aph[2"]-Ie) conferring high-level gentamicin resistance and a spectinomycin resistance gene ant(9)-Ia (aad 9) in clinical isolates of enterococci.

Aminoglycoside-modifying enzymes (AMEs) are major factors that confer aminoglycoside resistance to enterococci. In an epidemiologic study on distribution of 12 AME genes in 534 recent clinical strains isolated from a Japanese hospital, two uncommon AME genes, ant(9)-Ia and a novel aph(2") allele, aph(2")-Ie, were detected. ant(9)-Ia had been reported only in Staphylococcus aureus and encodes spectinomycin adenylyltransferase ANT(9)-I, which confers resistance to spectinomycin. The ant(9)-Ia gene was detected in three strains, a single strain each of Enterococcus faecalis, E. faecium, and E. avium. Nucleotide sequences of ant(9)-Ia from these three enterococcal species were identical to that reported for S. aureus and considered to be located on Tn 554. The new aph(2") allele, designated aph(2")-Ie, was identified in three E. faecium strains. The aph(2")-Ie allele was genetically close to aph(2")-Id reported in E. casseliflavus (93.7% amino acid sequence identity; 96.3% similarity), while distant from aph(2")-Ia, aph(2")-Ib, or aph(2")-Ic (26.3-29.5% amino acid sequence identity). Sequence divergence between APH(2")-Id and APH(2")-Ie was mostly located in amino-terminal half. In contrast, sequences corresponding to the three motifs required for aminoglycoside phosphotransferase were conserved except for a single amino acid. Three E. faecium strains having aph(2")-Ie showed high-level resistance to gentamicin and streptomycin, but not to kanamycin, dibekacin, and tobramycin, unlike enzyme specificity described for aph(2")-Id in E. casseliflavus. Such a difference in resistance phenotype was suggested to be related to amino acid sequence divergence between APH(2")-Id and APH(2")-Ie.

Alleles↗

PubMed2005

Community-based suicide prevention through group activity for the elderly successfully reduced the high suicide rate for females.

The lack of social support is the most common risk factor for late-life suicide. Few previous community-based interventions against the lack of social relationships reduced suicide. This study aims to evaluate outcomes of a community-based prevention program against suicide amongst the elderly in rural Japan. During 1995-2002, the program based on population strategy including group activity, psychoeducation and self-assessment of depression but no screening for depression, was implemented for elderly residents in Yuri town, Japan (5-year average population 6817; 5-year average suicide rate [> or =65 years old] 291.4/10(5)). Changes in the relative risk of suicide for individuals (> or =65 years old) before and after the 8-year implementation were estimated by the incidence rate ratio (IRR), using a quasi-experimental design with a neighboring reference, Chokai town, Japan (5-year average population 8136; 5-year average suicide rate [> or =65 years old] 216.5/10(5)). The risk of elderly females in Yuri completing suicide was reduced by 76% (age-adjusted IRR, 0.24; 95% CI, 0.10-0.58), while there was no change in the risks for Yuri's elderly males and both Chokai's elderly males and females. General loglinear analysis estimated a ratio of the female IRR in Yuri to that in its Akita prefecture of 0.35 (95% CI, 0.14-0.84), showing that the reduction of the risk in the intervention area was greater than a historical trend. A community-based suicide prevention through a group intervention designed to increase knowledge and to cultivate social relationships would be effective for elderly females but not males.

Age Factors↗

PubMed2005

Fish mesonephric model of polycystic kidney disease in medaka (Oryzias latipes) pc mutant.

BACKGROUND: Polycystic kidney disease (PKD) is a common hereditary disease. A number of murine and zebrafish mutants have been generated and used for the study of PKD as metanephric and pronephric models, respectively. Here, we report a medaka (Oryzias latipes) mutant that develops numerous cysts in the kidney in adulthood fish in an autosomal-recessive manner as a mesonephric model of PKD. METHODS: The phenotypes of the medaka pc mutant were described in terms of morphologic, histologic, and ultrastructural features. The pc see-through stock was produced by crossing a pc mutant and a fish from the see-through stock and used for observing the kidney through the transparent body wall of a live fish. RESULTS: The mutant developed bilateral massive enlargement of the kidney in adulthood. They sexually matured normally within 2 months of age and died within 6 months of age. The affected kidney was occupied by numerous, fluid-filled cysts, which were lined by attenuated squamous epithelial cells. Developmentally, cystic formation began in the pronephros in 10-day-old fry and in the mesonephros in 20-day-old fry at the microscopic level. The pc see-through stock was useful in observing disease progression in live fish. CONCLUSION: The kidney disorder that develops in the medaka pc mutant is a mesonephric counterpart of PKD, particularly an autosomal-dominant PKD, based on its morphologic, histologic, and ultrastructural features, and slow progression.

Animals↗

PubMed2005