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Biomedical subjects

Sunao Kawano

Publications and source records attributed to Sunao Kawano.

At least 19 recordsLinked to original sources
PubMed2006

Fucosylated haptoglobin is a novel marker for pancreatic cancer: a detailed analysis of the oligosaccharide structure and a possible mechanism for fucosylation.

Changes in oligosaccharide structures have been reported in certain types of malignant transformations and, thus, could be used for tumor markers in certain types of cancer. In the case of pancreatic cancer cell lines, a variety of fucosylated proteins are secreted into their conditioned media. To identify fucosylated proteins in the serum of patients with pancreatic cancer, we performed western blot analyses using Aleuria Aurantica Lectin (AAL), which is specific for fucosylated structures. An approximately 40 kD protein was found to be highly fucosylated in pancreatic cancer and an N-terminal analysis revealed that it was the beta chain of haptoglobin. While the appearance of fucosylated haptoglobin has been reported in other diseases such as hepatocellular carcinoma, liver cirrhosis, gastric cancer and colon cancer, the incidence was significantly higher in the case of pancreatic cancer. Fucosylated haptoglobin was observed more frequently at the advanced stage of pancreatic cancer and disappeared after an operation. A mass spectrometry analysis of haptoglobin purified from the serum of patients with pancreatic cancer and the medium from a pancreatic cancer cell line, PSN-1, showed that the alpha 1-3/alpha 1-4/alpha 1-6 fucosylation of haptoglobin was increased in pancreatic cancer. When a hepatoma cell line, Hep3B, was cultured with the conditioned media from pancreatic cancer cells, haptoglobin secretion was dramatically increased. These findings suggest that fucosylated haptoglobin could serve as a novel marker for pancreatic cancer. Two possibilities were considered in terms of the fucosylation of haptoglobin. One is that pancreatic cancer cells, themselves, produce fucosylated haptoglobin; the other is that pancreatic cancer produces a factor, which induces the production of fucosylated haptoglobin in the liver.

Biomarkers, Tumor↗
PubMed2006

Helicobacter pylori eradication to prevent gastric cancer: underlying molecular and cellular mechanisms.

Numerous cellular and molecular events have been described in development of gastric cancer. In this article, we overviewed roles of Helicobacter pylori (H pylori) infection on some of the important events in gastric carcinogenesis and discussed whether these cellular and molecular events are reversible after cure of the infection. There are several bacterial components affecting gastric epithelial kinetics and promotion of gastric carcinogenesis. The bacterium also increases risks of genetic instability and mutations due to NO and other reactive oxygen species. Epigenetic silencing of tumor suppressor genes such as RUNX3 may alter the frequency of phenotype change of gastric glands to those with intestinal metaplasia. Host factors such as increased expression of growth factors, cytokines and COX-2 have been also reported in non-cancerous tissue in H pylori-positive subjects. It is noteworthy that most of the above phenomena are reversed after the cure of the infection. However, some of them including overexpression of COX-2 continue to exist and may increase risks for carcinogenesis in metaplastic or dysplastic mucosa even after successful H pylori eradication. Thus, H pylori eradication may not completely abolish the risk for gastric carcinogenesis. Efficiency of the cure of the infection in suppressing gastric cancer depends on the timing and the target population, and warrant further investigation.

Animals↗
PubMed2006

Palmitoylation of LAT contributes to its subcellular localization and stability.

Palmitoylation is a protein modification for trafficking to lipid raft. Without palmitoylation, linker for activation of T cells (LAT), an adaptor molecule mediating T cell receptor signaling, is unable to localize in lipid rafts and to mediate T cell activation. We here show a novel role for palmitoylation in LAT trafficking to the plasma membrane and in the stability of the LAT protein. The human LAT mutant lacking palmitoylation was unable to traffic to the plasma membrane despite the presence of transmembrane portion. The mouse LAT mutant lacking palmitoylation was unstable and susceptible to degradation via the proteasome pathway. The human LAT mutant became unstable when the extracellular portion was swapped for that from mouse, indicating that both palmitoylation and the extracellular portion regulate the stability of LAT. These results suggest that palmitoylation has an important role in trafficking to the plasma membrane and the stability of LAT.

Acylation↗
PubMed2006

Influences of Helicobacter pylori on cyclooxygenase-2 expression and prostaglandinE2 synthesis in rat gastric epithelial cells in vitro.

BACKGROUND AND AIM: It is known that cyclooxygenase (COX)-2 is over expressed in gastrointestinal neoplasia and Helicobacter pylori (H. pylori) infection is causally linked to gastric cancer. The present study aimed to elucidate the effects of H. pylori on COX-2 expression and prostaglandinE(2) (PGE(2)) production in a gastric epithelial cell line derived from normal rat gastric mucosa (RGM1). METHOD: H. pylori water extracts were prepared from a supernatant of the H. pylori suspension in distilled water. RGM1 cells were cultured with H. pylori water extracts at the final concentration of 2.5, 5, 10 microg/mL for 24 h. For the time sequence study, RGM1 cells were cultured with 10 microg/mL H. pylori water extracts for 0, 6, 12, 24 and 48 h. COX-1 and COX-2 expression in the RGM1 cells was analyzed by western blotting. The levels of PGE(2) in the cultured media were measured by enzyme immunoassay. RESULTS: H. pylori did not affect COX-1 expression; whereas COX-2 expression increased by six-fold at 24 h after incubation of RGM1 cells with 10 microg/mL H. pylori water extracts. The increase in COX-2 expression was evident after 12 h of incubation; reached a peak at 24 h and declined at 48 h. H. pylori dose dependently increased COX-2 expression and PGE(2) synthesis in RGM1 cells. CONCLUSION: H. pylori induces COX-2 expression and increases PGE(2) synthesis in RGM1 cells in vitro. These results indicate that H. pylori-associated gastric carcinogenesis may depend on COX-2 expression.

Animals↗
PubMed2006

Oral glucose tolerance test predicts prognosis of patients with liver cirrhosis.

OBJECTIVE: The aim of this study was to evaluate whether oral glucose tolerance test (OGTT) was useful in evaluating the prognosis of patients with liver cirrhosis. METHODS: Fifty-six patients with liver cirrhosis were enrolled in a prospective cohort study. In all cases, glucose tolerance was diagnosed by a 75-g OGTT according to World Health Organization (WHO) criteria. The relationship of clinical variables to the cirrhosis-related prognosis was investigated using univariate and multivariate regression models. RESULTS: Diabetes mellitus (DM) was diagnosed in 21 subjects (38%), impaired glucose tolerance (IGT) in 13 subjects (23%), and normal glucose tolerance (NGT) in 22 subjects (39%) using OGTT. The cumulative survival rates of patients with liver cirrhosis and NGT were 94.7% at 5 yr; liver cirrhosis and IGT, 68.8% at 5 yr; liver cirrhosis and DM, 56.6% at 5 yr. The survival rates of patients with liver cirrhosis and DM significantly differed from those with NGT. Univariate analysis demonstrated that serum albumin, total bilirubin, prothrombin activity, Child-Pugh scores, and glucose intolerance were highly significant prognostic factors. Multiple regression analysis yielded albumin and DM as the most powerful independent negative predictors of survival. CONCLUSIONS: OGTT appears to be useful for evaluating the prognosis of cirrhotic patients.

Aged↗
PubMed2005

Endothelin-1, an ulcer inducer, promotes gastric ulcer healing via mobilizing gastric myofibroblasts and stimulates production of stroma-derived factors.

Endothelin (ET)-1 is a potent inducer of peptic ulcers. The roles of ET-1 in ulcer healing, however, have remained unclear, and these were investigated in mice. Gastric ulcers were induced in mice by serosal application of acetic acid. Three days later, mice were given a neutralizing ET-1 antibody or nonimmunized serum. The ulcer size, amount of fibrosis and myofibroblasts, and localization of ET-1 and ET(A/B) receptors were analyzed. To elucidate the mechanisms underlying the effects of ET-1, we examined the proliferation, migration, and release of growth and angiogenic factors in gastric myofibroblasts with or without ET-1. The expression of prepro-ET-1 (an ET-1 precursor) and ET-converting enzyme-1 was examined in gastric myofibroblasts using RT-PCR. Immunoneutralization of ET-1 delayed gastric ulcer healing. The areas of fibrosis and myofibroblasts were smaller in the anti-ET-1 antibody group than in the control. ET-1 was expressed in the gastric epithelium, myofibroblasts, and other cell types. ET(A) receptors, but not ET(B) receptors, were present in myofibroblasts. ET-1 increased proliferation and migration of gastric myofibroblasts. ET-1 stimulated the release of hepatocyte growth factor, VEGF, PGE(2), and IL-6 from gastric myofibroblasts. mRNA for prepro-ET-1 and ET-converting enzyme-1 was also expressed. ET-1 promotes the accumulation of gastric myofibroblasts and collagen fibrils at gastric ulcers. ET-1 also stimulates migration and proliferation of gastric myofibroblasts and enhances the release of growth factors, angiogenic factors, and PGE(2). Thus ET-1 has important roles not only in ulcer formation but also in ulcer healing via mobilizing myofibroblasts and inducing production of stroma-derived factors.

Angiogenesis Inducing Agents↗
PubMed2005

(2E,6Z,10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol (Plaunotol) increases cyclooxygenase-2 expression via nuclear factor kappaB and cyclic AMP response element in rat gastric epithelial cells.

Plaunotol, [(2E,6Z,10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol], a gastroprotective agent, increases the prostaglandin production in the gastric mucosa and accelerates ulcer healing. The precise mechanisms underlying the gastroprotective actions by plaunotol are not known. On the other hand, cyclooxygenase (COX)-2 is a key enzyme in PGE(2) production and its induction is thought to have an important role in ulcer healing. We investigated the mechanism of plaunotol-mediated COX-2 induction in rat gastric epithelial (RGM1) cells. We used a PGE(2) enzyme-linked immunoassay kit and Western blot analysis to measure PGE(2) production and COX-2 induction with plaunotol treatment in serum-starved RGM1 cells. In addition, gel-shift assay, Western blot analysis and a reporter assay were performed to observe which Cox-2 promoter was involved in plaunotol-induced Cox-2 expression. The findings indicated that plaunotol treatment dose-dependently increased COX-2 expression and PGE(2) production. The nuclear factor kappaB (NF-kappaB) and cyclic AMP response element (CRE) sites of the COX-2 gene promoter were critical to plaunotol-mediated COX-2 expression. In conclusion, plaunotol induced COX-2 expression and increased PGE(2) production in serum-starved RGM1 cells via activation of the NF-kappaB and CRE sites of Cox-2 gene promoters.

Animals↗
PubMed2005

Structure and function of lipid rafts in human activated T cells.

Lipid rafts, specialized membrane microdomains enriched in sphingolipids and cholesterol, have been shown to function as signaling platforms in T cells. Surface raft expression is known to be increased in human T cells upon activation, and this increased raft expression may account for efficient signaling capability and decreased dependency for co-stimulation in effector and/or activated T cells. However, raft-mediated signaling ability in activated T cells remains to be clarified. In this study, we analyzed the structure and function of lipid rafts in human activated T cells. We demonstrated that raft protein constituents are dramatically changed after activation along with an increase in lipid contents. T cells stimulated with anti-CD3 plus anti-CD28 antibodies showed an increase not only in surface monosialoganglioside GM1 expression but also in total amounts of raft-associated lipids such as sphingomyelin, cholesterol and glycosphingolipids. Raft proteins increased after activation include Csk, Csk-binding protein and Fyn, the molecules known to be involved in negative regulation of T cell activation. Consistent with the increase in expression of these proteins, TCR-mediated Ca(2+) response, a response dependent on raft integrity, was clearly inhibited in activated T cells. Thus, the structure and function of lipid rafts in human activated T cells seem to be quite distinct from those in naive T cells. Further, human activated T cells are relatively resistant to signaling, at least transiently, by TCR re-stimulation even though their raft expression is increased.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Efficiency of bone marrow-derived cells in regeneration of the stomach after induction of ethanol-induced ulcers in rats.

BACKGROUND: Bone marrow contains hematopoietic stem cells, nonhematopoietic mesenchymal stem cells, and several precursor cells for osteoblasts, chondrocytes, adipocytes, myocytes, hepatocytes, and even neural cells. Research findings indicate that multipotent stem cells in the adult body may be used to recover the lost functions of damaged tissues. This study examined the involvement of bone marrow-derived cells in the regeneration of the stomach after experimental gastric ulcers were produced in rats. METHODS: We transplanted the bone marrow of transgenic rats that expressed green fluorescence protein (GFP) throughout the body. Twenty-one days after the bone marrow transplantation (BMT), gastric ulceration was induced, using absolute ethanol. Control animals received saline. After various observation periods, rats harboring GFP-positive bone marrow-derived cells were killed, and the tissues were removed and processed to prepare paraffin-embedded sections. Cells expressing GFP were identified by conventional immunohistochemistry, using anti-GFP antibody. To identify whether cells expressing GFP were epithelial cells or interstitial cells such as fibroblasts, serial sections were examined with anti-cytokeratin antibody or anti-vimentin antibody, respectively. Furthermore, to confirm that cells expressing GFP were epithelial cells or interstitial cells, we used double-staining analysis with anti-GFP antibody or anti-cytokeratin antibody, respectively. RESULTS: GFP-positive, bone marrow-derived cells were found in the cytokeratin-positive gastrointestinal epithelium, as well as among vimentin-positive interstitial cells. Interestingly, the proportions of GFP-positive, cytokeratin-positive epithelial cells and vimentin-positive interstitial cells were significantly greater in the ethanol-treated damaged stomachs than in the saline-treated controls. CONCLUSIONS: The present study clearly demonstrates that bone marrow-derived cells are involved in the regeneration of the stomach after ethanol-induced ulcers in rats.

Animals↗
PubMed2005

Gastro-protective agent rebamipide induces cyclooxygenease-2 (COX-2) in gastric epithelial cells.

Cyclooxyngease-2 (COX-2) is a key enzyme in prostaglandin (PG) synthesis, and COX-2 induction plays an important role in the healing of gastric ulceration. Rebamipide is a gastro-protective agent and attenuates the activity of neutrophils. A number of reports have shown that rebamipide treatment increases PG production in the gastric mucosa {in vivo}. Although its clinical significance in ulcer healing has been demonstrated, {in vitro} evidence remains to be accumulated. Non-transformed rat gastric mucosal cells (RGM1 cells) were stimulated with rebamipide. RT-PCR and Western blot analysis revealed time and dose-dependent transcriptional and translational stimulation of COX-2. PGE(2) was also produced dose-dependently. However, marked COX-2 induction by rebamipide was transient and lasted less than 24 hr. COX-1 expression was unaltered by rebamipide. Reporter assay results confirmed the stimulation of Cox-2 promoter activity by rebamipide. In conclusion, this study provides {in vitro} evidence that rebamipide transcriptionally induces COX-2 and supports the rationale for its clinical use.

Alanine↗
PubMed2004

Targeted gene delivery to sinusoidal endothelial cells: DNA nanoassociate bearing hyaluronan-glycocalyx.

Liver sinusoidal endothelial cells (SECs) possess unique receptors that recognize and internalize hyaluronic acid (HA). To develop a system for targeting foreign DNA to SECs, comb-type polycations having HA side chains were prepared by coupling HA to poly(L-lysine) (PLL). The HA-grafted-PLL copolymer (PLL-g-HA) thus formed was mixed with DNA in 154 mM NaCl to form soluble nanoassociates bearing hydrated hyaluronate shells. Agarose gel retardation assays revealed selective interaction of the PLL backbone with DNA despite the presence of polyanionic HA side chains. To determine whether the PLL-g-HA/DNA complexes were recognized by SEC HA receptors in vivo, we injected Wistar rats i.v. via the tail vein with PLL-g-HA complexed to a beta-galactosidase expression plasmid (pSV beta-Gal) labeled with 32P. One hour postinjection, >90% of the injected radioactivity remained in the liver. Administration of the PLL-g-HA complexed to an FITC-labeled DNA revealed that the carrier-DNA complex was distributed exclusively in SECs. A large number of SECs expressing beta-galactosidase was detected along the sinusoidal lining after transfection with PLL-g-HA/pSV beta-Gal. Moreover, PLL-g-HA effectively stabilized DNA triplex formation. In conclusion, the new PLL-g-HA/DNA carrier system permits targeted transfer of exogenous genes selectively to the SECs.

Animals↗