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Shinsuke Saito

Publications and source records attributed to Shinsuke Saito.

6 recordsLinked to original sources
PubMed2006

Effects of down-regulating the Id genes in human colorectal cancer cells on early steps of haematogenous metastasis.

Id genes (inhibitor of DNA binding/differentiation) play important roles in tumour growth. We have previously described crucial roles of Id gene over-expression in endothelial cells for tumour angiogenesis. Here, we have evaluated direct effects of Id gene down-regulation on tumour cells, namely on cell proliferation, motility, and adhesion to lung microvasculature during haematogenous metastasis. For this purpose, Id genes were stably down-regulated by RNA interference in human colorectal cancer cells. These cells showed delayed proliferation, inhibited motility and decreased expression of integrin alpha6 and consequently reduced adhesion to lung microvasculature in mice. Static adhesion assays and laminar flow assays revealed decreased laminin binding capacity of these cells, and blocking experiments confirmed that it could be attributed to decreased expression of integrin alpha6. The present results indicate important roles of Id genes in tumour cells during early steps of haematogenous metastasis and suggest dual effects from their therapeutic inhibition.

Animals↗
PubMed2004

A novel method for isolation of endothelial cells and macrophages from murine tumors based on Ac-LDL uptake and CD16 expression.

Analysis of specific properties of tumor endothelium should be useful for development of novel antiangiogenic strategies. However, the isolation of pure endothelial cells from tumor tissues is still a fundamental problem. In this study, we have attempted to develop a reliable method for the isolation of endothelial cells from murine tumors. We found that the labeling with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-acetylated-low density lipoprotein (Dil-Ac-LDL), commonly used for this purpose, can result in the contamination of isolated endothelium by macrophages due to the overlapping staining patterns of these two distinct cell types. Therefore, we chose the CD16, which is expressed on macrophages but not endothelial cells, to better distinguish them when labeled with Dil-Ac-LDL. By using this method, we obtained pure populations of endothelial cells and macrophages from murine colorectal cancer tissues, showing characteristic morphological and functional properties of the either cell type. The endothelial cells were long spindle-shaped, spread on gelatin, formed tube-like structures on Matrigel and expressed MECA-32 but not CD68. In contrast, the macrophages were round-shaped, partially spread on gelatin, formed unorganized aggregates on Matrigel and expressed CD68 but not MECA-32. The additional analysis of normal and tumor tissues revealed a positive correlation between the relative numbers of tumor endothelial cells and macrophages, calculated as % total cells, as well as the respective relative number and tumor weight. The present method is hoped to be useful for the evaluation of tumor angiogenesis and antitumor immunity.

Animals↗
PubMed2004

Vaccination with autologous endothelium inhibits angiogenesis and metastasis of colon cancer through autoimmunity.

Overcoming immune tolerance of tumor angiogenesis should be useful for adjuvant therapy of cancer. We hypothesized that vaccination with autologous endothelium would induce an autoimmune response targeting tumor angiogenesis. To test this concept, we immunized BALB/c mice with a vaccine of glutaraldehyde-fixed murine hepatic sinusoidal endothelial cells (HSEs) in a lung metastasis model of Colon-26 cancer. Vaccination with autologous HSEs induced both preventive and therapeutic anti-tumor immunity that significantly inhibited the development of metastases. ELISA revealed an immunoglobulin response involving IgM and IgG subclasses. These antibodies had a strong affinity for antigens of both murine and human endothelium, and lyzed endothelial cells in the CDC assay. Flow-cytometry and chromium-release cytotoxicity assay revealed a specific CTL response against endothelial cells, which were lyzed in an effector: target ratio-dependent manner. Neither antibodies nor CTLs reacted with Colon-26. The effect of autologous HSEs was more pronounced than that of xenogeneic human umbilical vein endothelial cells (HUVECs), which were tested in the same experimental setting. Our results suggest that vaccination with autologous endothelium can overcome peripheral tolerance of self-angiogenic antigens and therefore should be useful for adjuvant immunotherapy of cancer.

Animals↗
PubMed2003

Expression of platelet-derived endothelial cell growth factor in inflammatory bowel disease.

BACKGROUND: Platelet-derived endothelial cell growth factor (PD-ECGF) is reported to be highly expressed in tumors and inflammatory tissues, but its expression and role in inflammatory bowel disease (IBD) are still unclear. In this study we examined the location and tissue density of cells immunoreactive for PD-ECGF in the colonic mucosa of IBD. METHODS: Paraffin-embedded sections of colonic tissue from patients with ulcerative colitis (UC) or Crohn's disease (CD) were immunostained for PD-ECGF. As controls, noninflamed mucosa of IBD, as well as normal colonic mucosa from patients with colorectal cancer, were used. Also, cancer tissues were evaluated. In addition, changes in the expression of PD-ECGF in human umbilical vein endothelial cells (HUVEC) after treatment with inflammatory cytokines and angiogenic factors, as well as after coculture with colon cancer cell lines, were evaluated by flow cytometry. RESULTS: In normal colonic mucosa and noninflamed mucosa of IBD, PD-ECGF expression was negligible. In inflamed colonic mucosa, strong expression was observed, predominantly in macrophages and fibroblasts. Vascular endothelial cells of the inflamed colonic mucosa, but not of normal colonic mucosa or of neoplastic tissues, stained for PD-ECGF, and the microvessel density was significantly increased in the severely inflamed mucosa. Flow cytometry demonstrated that PD-ECGF was constitutively expressed in HUVEC. Inflammatory cytokines and vascular endothelial growth factor (VEGF) increased its expression, whereas basic fibroblast growth factor (bFGF) decreased it. Coculture with colon cancer cell lines in direct contact, but not in those without contact, also resulted in an important decrease in the expression of PD-ECGF in HUVEC. CONCLUSIONS: Autocrine production of PD-ECGF by endothelial cells may be a mechanism of inflammatory angiogenesis, but not tumor angiogenesis, and may be particularly important for the maintenance of damaged vasculature in IBD.

Colitis, Ulcerative↗
PubMed2002

Decreased synthesis of matrix metalloproteinase-7 and adhesion to the extracellular matrix proteins of human colon cancer cells treated with troglitazone.

PURPOSE: In the present study, we investigated the effect of troglitazone, a selective ligand and agonist of PPAR-gamma, on the metastatic potential of human colon cancer cells. METHODS: High- and low-PPAR-gamma expression clones of the colon cancer cell line, HT29, namely clones 21 and 3 respectively, were used. We investigated the effect of troglitazone on the proliferation, on the adhesion to extracellular matrix proteins and on the synthesis of matrix metalloproteinases (MMPs) of colon cancer cells. RESULTS: Troglitazone inhibited the proliferation of both subclones, in a dose-dependent manner, and the inhibitory effect correlated with the level of PPAR-gamma expression. Troglitazone strongly inhibited the production of MMP-7, an enzyme associated with invasiveness of cancer cells, by both subclones. In addition, troglitazone caused a strong decrease in the adhesion of clone 21 to extracellular matrix (ECM) proteins, laminin and type IV collagen. This effect was independent of beta1-integrins expression CONCLUSION: In addition to inhibition of cancer cell growth, troglitazone had an inhibitory effect on two important events associated with the metastatic potential of cancer cells, production of MMPs and adhesion to ECM proteins. Consequently, troglitazone is a promising agent for the treatment and prevention of colon cancer metastasis.

Antineoplastic Agents↗