PubMed Health⌕ Search

Biomedical subjects

Kazushi Sugimoto

Publications and source records attributed to Kazushi Sugimoto.

At least 19 recordsLinked to original sources
PubMed2006

A novel mechanism for drug-induced liver failure: inhibition of histone acetylation by hydralazine derivatives.

BACKGROUND/AIMS: The aim of this study was to investigate the precise mechanism of liver failure by hydralazine derivatives, with special reference to liver regeneration failure. METHODS: Histone acetylation and proliferation of hepatocytes were evaluated by immunohistochemistry with anti-acetylated histone H4 and proliferating cell nuclear antigen (PCNA). Inhibition of histone acetylation by drugs was determined by in vitro histone acetylation assay. Mice livers fed with todralazine for 1 or 4 months were subjected to immunohistochemistry and Western blotting. Todralazine-fed mice were challenged with anti-Fas to check liver regeneration failure. RESULTS: On immunohistochemistry, histone acetylation in the hepatocytes was significantly impaired in patients with hydralazine derivatives. In an in vitro acetyl transferase assay, histone acetylation was inhibited by hydralazine derivatives in a dose-dependent manner. Mice fed with todralazine (3mg/day) for 4 months showed impairment of histone acetylation in hepatocytes whereas no inhibition was observed in mice fed with todralazine for 1 month. Anti-Fas challenge to todralazine-fed mice resulted in impairment of liver regeneration in respect of liver weight loss with impairment of histone acetylation in hepatocytes. CONCLUSIONS: Todralazine could inhibit catalysis of histone acetyltransferase and long-term administration of todralazine may impair histone acetylation of the hepatocytes, resulting in liver regeneration failure.

Acetylation↗
PubMed2006

Identification of novel hepatitis C virus-specific cytotoxic T lymphocyte epiotpe in NS3 region.

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) are thought to be effective in limiting viral spread and in clearing virus during infection. Therefore, we attempted to establish HCV-specific CTL and identify novel HCV-specific CTL epitopes in a patient with acute hepatitis C by a novel screening method using recombinant vaccinia viruses (rVV) and synthetic peptides. CD8(+)CD45RA(-) T cells (memory T cells) were isolated from peripheral blood mononuclear cells (PBMC) of a patient with acute hepatitis C. HCV-specific CTL were cloned at limited dilutions and tested for HCV-specific CTL activity using a standard (51)Cr release assay. CTL assay was performed using rVV expressing regions of HCV-J, and overlapping and truncated synthetic peptides from HCV-J. CTL recognizing the NS3 region were isolated by (51)Cr release assay with rVV-HCV. Isolated CTL were restricted by HLA class I molecules B(*)5603. We confirmed that isolated CTL recognized 8-mer amino acids in the NS3 region of HCV-J by (51)Cr release assay with overlapping and truncated synthetic peptides. In conclusion, we isolated HCV-specific CTL restricted by HLA-B(*)5603 and identified a novel HCV-specific CTL epitope (IPFYGKAI, amino acids 1373-1380) in the NS3 region. The identified HCV-specific CTL epitope might be useful for HCV therapy.

Journal Article↗
PubMed2006

Proteasome inhibition sensitizes hepatocellular carcinoma cells to TRAIL by suppressing caspase inhibitors and AKT pathway.

The ubiquitin-proteasome pathway is responsible for regulating cell cycle proteins, tumor-suppressor molecules, oncogenes, transcription factors, and pro- and anti-apoptotic proteins. The aim of this study is to evaluate the effects of proteasome inhibitors on human hepatocellular carcinoma (HCC) cells. HCC cells SK-Hep1, HLE and HepG2 were treated with the proteasome inhibitors MG132 and MG115. Our data showed that both inhibitors induce apoptosis in the three cell types tested in a dose-dependent manner. Moreover, subtoxic levels of MG132 and MG115 sensitized HCC cells to TRAIL-induced apoptosis. To investigate the mechanism of increased TRAIL sensitivity in HCC cells, we first examined surface expression of TRAIL and its receptors. MG132 upregulated TRAIL and its receptors (TRAIL-R1 and -R2) in SK-Hep1 and HLE, whereas MG115 upregulated them in SK-Hep1. MG132 downregulated expression of X-linked inhibitor of apoptosis protein (XIAP) in SK-Hep1 and HLE, and of survivin in all three cell-types. MG115 downregulated expression of XIAP in SK-Hep1, and survivin in SK-Hep1 and HepG2. Furthermore, MG132 downregulated phospho-AKT and its downstream target phospho-BAD, indicating that MG132 activated the mitochondrial apoptosis pathway by inhibiting phosphorylation of AKT and BAD. In conclusion, proteasome inhibitors induced apoptosis and augmented TRAIL sensitivity via both the IAP family and AKT pathways. Thus, combining proteasome inhibitors with a TRAIL agonist may provide a new therapeutic strategy for HCC.

Animals↗
PubMed2006

COX-2 inhibitors sensitize human hepatocellular carcinoma cells to TRAIL-induced apoptosis.

Cyclooxygenase (COX)-2 is upregulated in a variety of human cancers, including in hepatocellular carcinoma (HCC), whereas it is undetectable in most normal tissue. Evidence suggests that COX-2 is likely to be involved in hepatocarcinogenesis and, thus, COX-2 may be involved in an early process in carcinogenesis, dedifferentiation. To address this possibility, we investigated the effect of COX-2 inhibitors on TNF-related apoptosis, inducing ligand (TRAIL) sensitivity and its molecular mechanisms, with special attention to anti-apoptotic proteins. We used the highly selective COX-2 inhibitors, NS398 and CAY10404. We also used the MTT assay and cytological analysis of DAPI-stained DNA to assess viability and apoptosis in two HCC cells (SK-Hep1 and HLE). In order to ask what led to increased sensitivity to TRAIL in HCC cells, cell surface expression of TRAIL and TRAIL-receptors was investigated using flow cytometry analysis. Expression of survivin, X-chromosome-linked IAP (XIAP), Bcl-xL, AKT and phospho-AKT was also investigated using immunoblotting. COX-2 inhibitors resulted in a concentration-dependent decrease in cell viability in the two HCC cell lines tested. Subtoxic levels of COX-2 inhibitors did not significantly augment TNFalpha-induced apoptosis but did dramatically enhance TRAIL-induced apoptosis in both cell lines. TRAIL receptor 2/death receptor 5 (TRAIL-R2/DR5) expression was significantly up-regulated in SH-Hep1 and HLE cells. TRAIL receptor 1/death receptor 4 (TRAIL-R1/DR4) expression was up-regulated only in SK-Hep1. Expression of survivin and Bcl-xL was down-regulated in SK-Hep1 and HLE cells in the presence of CAY10404 but XIAP was not affected. Expression of survivin, Bcl-xL and XIAP was down-regulated in SK-Hep1 cells in the presence of NS398. Survivin expression was also down-regulated in the presence of NS398 in HLE cells. Finally, NS398 also decreased phospho-AKT in SK-Hep1 cells. These results demonstrate that COX-2 inhibitors can induce apoptosis and augment TRAIL sensitivity by up-regulation of TRAIL receptors and down-regulation of both survivin and AKT signaling.

Apoptosis↗
PubMed2006

Cellular apoptosis susceptibility protein and proliferation in human hepatocellular carcinoma.

The cellular apoptosis susceptibility protein (CAS) is the human homologue of the product of the essential yeast chromosome segregation gene, CSE1, and has important roles in tumor necrosis factor (TNF)-induced apoptosis and cell proliferation. In this study, we used immunoblotting and immunohistochemistry to look at CAS expression in human hepatocellular carcinoma (HCC) cells. We also studied the correlation between CAS expression and cell proliferation. To do this, we studied the expression of proliferating cell nuclear antigen (PCNA) by immunostaining and at apoptosis by in situ nick end-labeling (TUNEL), followed by calculation of the PCNA labeling index (PCNA LI) and TUNEL labeling index (TUNEL LI). CAS was constitutively expressed in human HCC cell lines and was primarily confined to the cytoplasm of the cells. PCNA LI and TUNEL LI were significantly higher in HCC than in non-tumor tissue (p<0.01); however, the ratio of TUNEL LI/PCNA LI in HCC was significantly lower than that of non-tumor tissue. Immunohistochemistry revealed that the staining intensity score of CAS in HCC was significantly higher than that of non-tumor tissue (p<0.05). These results indicate that there is an augmentation of pro-liferative activity and apoptosis in HCC tissue, as compared to non-tumor tissue. There was a significant positive correlation between CAS and PCNA LI (p<0.05). In addition, we observed an inverse relationship between CAS expression and TUNEL LI, although the correlation did not reach statistical significance. These results suggest that CAS is expressed at higher levels in human HCC tissue than in non-tumor tissue. CAS may be associated with cell proliferation rather than apoptosis, and further, CAS might play an important role in the development of human HCCs.

Apoptosis↗
PubMed2006

The cyclin-dependent kinase inhibitor flavopiridol sensitizes human hepatocellular carcinoma cells to TRAIL-induced apoptosis.

Flavopiridol was one of the first cyclin-dependent kinase inhibitors demonstrated to have an antitumor effect in several cancer types. Here, we investigated the effects of flavopiridol on TNF-related apoptosis-inducing ligand (TRAIL) in the human hepatocellular carcinoma (HCC) cell lines HLE and HepG2, and evaluated the role of flavopiridol in apoptosis. To better understand the mechanism of increased TRAIL sensitivity in HCC cells, we determined the effect of flavopiridol on cell surface expression of TRAIL and TRAIL receptors using flow cytometry analysis. The levels of survivin, FLIP, Bcl-xL and X-chromosome-linked IAP (XIAP) in treated and untreated cells was also determined. Flavopiridol decreased cell viability in a dose-dependent manner in the two HCC cell lines tested. The pan-caspase inhibitor z-VAD-FMK did not inhibit the effect. However, subtoxic levels of flavopiridol dramatically enhanced TRAIL-induced apoptosis in both cells. Flavopiridol up-regulated TRAIL, TRAIL-R1 and TRAIL-R2 in both cell lines. In addition, flavopiridol down-regulated expression of survivin in both cell lines, and expression of FLIP and Bcl-xL were down-regulated in HLE cells. In summary, flavopiridol augmented TRAIL sensitivity by up-regulation of TRAIL receptors and down-regulation of survivin, FLIP and Bcl-xL. Thus, combining flavopiridol with a TRAIL agonist may prove to be an effective new strategy for treatment of HCC.

Antineoplastic Agents↗
PubMed2006

CD40 expression in HCV-associated chronic liver diseases.

CD40 is expressed primarily on B cells and plays an important role in antigen presentation, B cell proliferation, and T cell activation. It has been reported that the CD40 signal modulates apoptosis and has an anti-viral effect in certain cells. Therefore, we investigated the expression and the function of CD40 in HCV-associated chronic liver disease. The expression of CD40 on liver tissues was determined through immunohistochemistry on 50 liver specimens obtained from HCV-positive patients. The effect of CD40 signaling on apoptosis of HepG2 cells was assessed using the MTT assay. The effect of CD40 stimulation on NF-kappaB activation was determined in NF-kappaB reporter gene-transfected HepG2 cells with the Luciferase assay. CD40 positive hepatocytes were observed in both periportal and lobular areas, accompanied by inflammation. In both areas, CD40 staining intensity became significantly stronger, correlating with the histological grading. Similarly, it became stronger with the progression of the histological staging in F1, F2 and F3 cases; however, the expression level decreased in F4 cases. CD40 ligation induced apoptosis in HepG2 cells in the presence of 500 ng/ml of actinomycin D, while CD40 ligation alone could not. Anti-CD40 monoclonal antibody caused NF-kappaB activation in HepG2 cells in a dose-dependent manner. These results suggest that hepatocyte over-expression of CD40 might play an important role in regulating hepatocyte survival and death in HCV-associated chronic liver diseases.

Antibodies, Monoclonal↗
PubMed2005

Relative predictive factors for hepatocellular carcinoma after HBeAg seroconversion in HBV infection.

AIM: To determine the predictive factors for hepatocellular carcinoma (HCC) development in patients after spontaneous or therapeutic HBeAg seroconversion. METHODS: In 48 patients who seroconverted to anti-HBe positive during follow-up, the background factors for HCC development were analyzed. RESULTS: HCC was developed in six patients during follow-up (average follow-up after HBeAg seroconversion: 10.9+/-5.4 years). The incidence of HCC evaluated by Kaplan-Meier analysis was significantly higher in patients with abnormal aspartate aminotransferase (AST>40 IU/L) level, lower platelet counts (PLT< 10 x 10(4)/microL), lower albumin level (Alb<30 g/L), positive HBV-DNA or older age at seroconversion (>40 years). However, lower platelet count was the only predictive factor for HCC development shown by multivariate proportional-hazard analysis. CONCLUSION: Active hepatitis or advanced hepatitis at HBeAg seroconversion or progressive hepatitis even after HBeAg seroconversion would be the risk factors for HCC development. These predictive factors should be taken into account in determining the frequency of biochemical study or imaging studies for HCC surveillance.

Adolescent↗
PubMed2005

Augmentation of tumor necrosis factor family-induced apoptosis by E3330 in human hepatocellular carcinoma cell lines via inhibition of NF kappa B.

AIM: To investigate the reduction of cell viability in human hepatocellular carcinoma (HCC) cell lines induced by inhibition of nuclear factor kappa B (NF kappa B). METHODS: HLE, SKHep1, and HepG2 were incubated and E3330 was used to compare the stimulation of some chemotherapeutic drugs with that of TNF family, Fas ligand, TNF alpha and TNF-related apoptosis-inducing ligand (TRAIL) at the point of the reduction of cell viability by inhibiting NF kappa B. RESULTS: E3330 decreased NF kappa B levels in HLE cells stimulated by TNF and TRAIL. The cytotoxicity of the combination of TRAIL, TNF alpha, Fas ligand, and E3330 increased synergistically in a dose-dependent manner compared to either E3330 alone in all HCC cell lines by MTT assay. However, the combination of some chemotherapeutic drugs and E3330 did not decrease the cell viability. CONCLUSION: Inhibition of NF kappa B sensitizes human HCC cell lines to TNF-mediated apoptosis including TRAIL, and TRAIL-based tumor therapy might be a powerful potential therapeutic tool in the treatment of human HCC.

Apoptosis↗
PubMed2005

Primary biliary cirrhosis after aortoiliac reconstruction surgery using a Y-graft.

Primary biliary cirrhosis (PBC) is an autoimmune disease characterized by anti-mitochondrial antibodies and destruction of intra-hepatic bile ducts. Though little is known about the etiology of PBC, some reports suggest that xenobiotics and viral infections may induce PBC. We describe a case of PBC after the aortoiliac reconstruction surgery using a Y-graft.

Aorta, Abdominal↗
PubMed2005

Functional expression of a proliferation-related ligand in hepatocellular carcinoma and its implications for neovascularization.

AIM: To detect the expression of a proliferation-related ligand on human hepatocellular carcinoma (HCC) cell lines (SK-Hep1, HLE and HepG2) and in culture medium. METHODS: APRIL expression was analyzed by Western blotting in HCC cell lines. Effects of APRIL to cell count and angiogenesis were analyzed, too. RESULTS: Recombinant human APRIL (rhAPRIL) increased cell viability of HepG2 cells and, in HUVEC, rhAPRIL provided slight tolerance to cell death from serum starvation. Soluble APRIL (sAPRIL) from HLE cells increased after serum starvation, but did not change in SK-Hep1 or HepG2 cells. These cells showed down-regulation of VEGF after incubation with anti-APRIL antibody. Furthermore, culture medium from the HCC cells treated with anti-APRIL antibody treatment inhibited tube formation of HUVECs. CONCLUSION: Functional expression of APRIL might contribute to neovascularization via an upregulation of VEGF in HCC.

Carcinoma, Hepatocellular↗
PubMed2005

Cardiac metastases of gallbladder carcinoma.

This report describes the case of a 68-year-old woman diagnosed with advanced gallbladder cancer, whose autopsy revealed multiple metastases, including cardiac metastases.

Adenocarcinoma↗
PubMed2005

Noninvasive estimation of liver fibrosis and response to interferon therapy by a serum fibrogenesis marker, YKL-40, in patients with HCV-associated liver disease.

AIM: To evaluate the clinical utility of serum fibrosis markers, including YKL-40, in patients with HCV-associated liver disease. METHODS: A total of 109 patients with HCV-associated liver disease were enrolled. We measured serum type IV collagen, amino-terminal peptide of type III procollagen (PIIIP), hyaluronic acid (HA), YKL-40 levels and biochemical. Parameters by RIA or ELISA. Eighty-eight patients underwent liver biopsy, and 67 of 109 patients received interferon (IFN) therapy. We also investigated the relationship between the concentrations of serum fibrosis markers and histological fibrosis scores (METAVIR), and evaluated the changes of the levels of fibrosis markers before and after the IFN therapy. RESULTS: The increase in serum levels of all markers, particularly HA, was correlated with the progression of liver fibrosis (for type IV collagen, F = 9.076, P<0.0001; for PIIIP, F = 9.636, P<0.0001; for HA, F = 13.128, P<0.0001; and for YKL-40, F = 8.016, P<0.0001). YKL-40 had strong correlation with HA (r = 0.536, P<0.0001). Based on the receiver operating curve (ROC), the ability of serum HA exceeded the abilities of other serum markers to determine fibrosis score 4 from fibrosis score 0-3 (AUC = 0.854). While YKL-40 was superior to other fibrosis markers for predicting severe fibrosis (F2-F4) from mild fibrosis (F0-F1) (YKL-40, AUC = 0.809; HA, AUC = 0.805). After IFN therapy, only YKL-40 values significantly decreased not only in the responder group, but also in the nonresponder group (P = 0.03). CONCLUSION: YKL-40 may be a useful non-invasive serum marker to estimate the degree of liver fibrosis and to evaluate the efficacy of IFN therapies in patients with HCV-associated liver disease.

Adipokines↗
PubMed2005

T-cell response relative to genotype and ethnicity during antiviral therapy for chronic hepatitis C.

Viral genotype and host ethnicity are important predictors of viral clearance during antiviral therapy for chronic hepatitis C virus (HCV) infection. Based on the role of T cells in natural HCV clearance, we hypothesized that T cells may contribute to the genotypic and ethnic difference in treatment outcome. To test this hypothesis, T-cell response to HCV antigens (core, nonstructural NS3/4 and NS5) and control phytohemagglutinin (PHA) was monitored prospectively and was correlated with virological outcome in 41 patients chronically infected with HCV (27 genotype 1, 14 genotype 2 or 3; 19 black persons, 22 white persons) undergoing combined interferon alfa and ribavirin therapy. Interestingly, in patients with genotype 2 or 3 infection, enhanced virological response coincided with a greater T-cell response to HCV NS3/4 antigen at baseline (50% vs. 15%; P = .026) that augmented further during therapy (29% vs. 4%; P = .035) compared with genotype 1-infected patients. However, HCV-specific T-cell response remained weak in genotype 1-infected patients regardless of virological outcome or ethnicity. Furthermore, virological outcome was associated with a suppressed baseline proliferative response to phytohemagglutinin (P < .03) that increased during therapy (P < .003) independent of ethnicity or genotype. In conclusion, HCV-specific T-cell response was associated with HCV genotype but not with therapeutic clearance of HCV infection. The association between treatment outcome and phytohemagglutinin response suggests more global and antigen-nonspecific mechanisms for therapeutic HCV clearance.

Antiviral Agents↗
PubMed2005

Involvement of tumor necrosis factor-related apoptosis-inducing ligand and tumor necrosis factor-related apoptosis-inducing ligand receptors in viral hepatic diseases.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in tumor cells, but not in most normal cells. The role of TRAIL in hepatic cell death and hepatic diseases is not well understood. The present study investigated the expression of TRAIL and TRAIL receptors (TRAIL-Rs) in patients with hepatitis C virus infection using immunohistochemistry and examined physiological roles under viral infection in the HepG2 cell line. Staining of TRAIL or TRAIL-Rs was prominent in the cytoplasm and membrane of hepatocytes in the periportal area. Some liver-infiltrating lymphocytes also displayed positive staining for TRAIL. Staining intensity was significantly increased with disease progression, particularly in the periportal area. AdCMVLacZ (Q-BIOgene, Carisbad, Calif) infection was also found to induce apoptosis in HepG2 cells and significantly augment TRAIL-induced apoptosis. Anti-TRAIL antibody significantly inhibited apoptosis induced by AdCMVLacZ infection. Flow cytometry analysis revealed that both TRAIL-R2 and TRAIL were up-regulated on the cell surface of HepG2 cells with AdCMVLacZ infection. Transforming growth factor-beta1 also enhanced TRAIL expression in HepG2 cells. These results indicate that TRAIL/TRAIL-R apoptotic pathways play important roles in the hepatic cell death during viral infection.

Adenoviridae Infections↗
PubMed2005

Vitamin K analog (compound 5) induces apoptosis in human hepatocellular carcinoma independent of the caspase pathway.

A systemic vitamin K analog, compound 5 (Cpd 5), possesses the ability to inhibit cell growth of tumor cells. Therefore, we investigated the effect of Cpd 5 in human hepatocellular carcinoma (HCC) cell lines and evaluated its role in apoptosis. Human HCC cell lines were cultured and treated with Cpd 5. Apoptosis was assessed using DAPI staining and Annexin-V membrane staining. The expression of caspases, XIAP and Bcl-xL was also investigated. Cpd 5 decreased cell viability in a dose-dependent manner in two HCC cells (HLE and SK-Hep1) containing mutant p53, but not in the HepG2 cell line, which contained wild-type p53. Cpd 5-treated HLE and SK-Hep1 cells showed typical apoptotic features, nuclear condensation and nuclear fragmentation upon DAPI staining. Positive membranous staining for Annexin-V was also seen in these cells. Both caspase-8 and caspase-3 activities were up-regulated slightly. Pro-caspase-8 protein levels decreased slightly in both cells. Although the expression of Bcl-xL was not influenced by Cpd 5, that of XIAP decreased in HLE cells. However, the pan-caspase inhibitor, zVAD, could not significantly prevent Cpd 5-induced apoptosis and Cpd 5 could not augment TRAIL-induced apoptosis. These results demonstrate that Cpd 5 induced apoptosis in human HCC cell lines, mainly independently of caspase activities. This may contribute to its highly potent cytotoxicity toward HCC cells.

Apoptosis↗
PubMed2005

Strain-specific T-cell suppression and protective immunity in patients with chronic hepatitis C virus infection.

Hepatitis C virus (HCV) frequently persists with an apparently ineffective antiviral T-cell response. We hypothesized that some patients may be exposed to multiple HCV subtypes and that strain-specific T cells could contribute to the viral dynamics in this setting. To test this hypothesis, CD4 T-cell responses to three genotype 1a-derived HCV antigens and HCV antibody serotype were examined in chronically HCV infected (genotypes 1a, 1b, 2, 3, and 4) and spontaneously HCV recovered subjects. Consistent with multiple HCV exposure, 63% of patients infected with genotypes 2 to 4 (genotypes 2-4) and 36% of those infected with genotype 1b displayed CD4 T-cell responses to 1a-derived HCV antigens, while 29% of genotype 2-4-infected patients showed serotype responses to genotype 1. Detection of 1a-specific T cells in patients without active 1a infection suggested prior self-limited 1a infection with T-cell-mediated protection from 1a but not from non-1a viruses. Remarkably, CD4 T-cell responses to 1a-derived HCV antigens were weakest in patients with homologous 1a infection and greater in non-1a-infected patients: proportions of patients responding were 19% (1a), 36% (1b), and 63% (2-4) (P = 0.0006). Increased 1a-specific CD4 T-cell responsiveness in non-1a-infected patients was not due to increased immunogenicity or cross-reactivity of non-1a viruses but directly related to sequence divergence. We conclude that the T-cell response to the circulating virus is either suppressed or not induced in a strain-specific manner in chronically HCV infected patients and that, despite their ability to clear one HCV strain, patients may be reinfected with a heterologous strain that can then persist. These findings provide new insights into host-virus interactions in HCV infection that have implications for vaccine development.

Case-Control Studies↗