Yurai Okaji
University of Tokyo
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Featured researches published by Yurai Okaji.
BMC Cancer | 2010
Kazuhito Sasaki; Nelson H. Tsuno; Eiji Sunami; Giichiro Tsurita; Kazushige Kawai; Yurai Okaji; Takeshi Nishikawa; Yasutaka Shuno; Kumiko Hongo; Masaya Hiyoshi; Manabu Kaneko; Joji Kitayama; Koki Takahashi; Hirokazu Nagawa
BackgroundChloroquine (CQ), the worldwide used anti-malarial drug, has recently being focused as a potential anti-cancer agent as well as a chemosensitizer when used in combination with anti-cancer drugs. It has been shown to inhibit cell growth and/or to induce cell death in various types of cancer. 5-Fluorouracil (5-FU) is the chemotherapeutic agent of first choice in colorectal cancer, but in most cases, resistance to 5-FU develops through various mechanisms. Here, we focused on the combination of CQ as a mechanism to potentiate the inhibitory effect of 5-FU on human colon cancer cells.MethodsHT-29 cells were treated with CQ and/or 5-FU, and their proliferative ability, apoptosis and autophagy induction effects, and the affection of the cell cycle were evaluated. The proliferative ability of HT-29 was analyzed by the MTS assay. Apoptosis was quantified by flow-cytometry after double-staining of the cells with AnnexinV/PI. The cell cycle was evaluated by flow-cytometry after staining of cells with PI. Autophagy was quantified by flow-cytometry and Western blot analysis. Finally, to evaluate the fate of the cells treated with CQ and/or 5-FU, the colony formation assay was performed.Results5-FU inhibited the proliferative activity of HT-29 cells, which was mostly dependent on the arrest of the cells to the G0/G1-phase but also partially on apoptosis induction, and the effect was potentiated by CQ pre-treatment. The potentiation of the inhibitory effect of 5-FU by CQ was dependent on the increase of p21Cip1 and p27Kip1 and the decrease of CDK2. Since CQ is reported to inhibit autophagy, the catabolic process necessary for cell survival under conditions of cell starvation or stress, which is induced by cancer cells as a protective mechanism against chemotherapeutic agents, we also analyzed the induction of autophagy in HT-29. HT-29 induced autophagy in response to 5-FU, and CQ inhibited this induction, a possible mechanism of the potentiation of the anti-cancer effect of 5-FU.ConclusionOur findings suggest that the combination therapy with CQ should be a novel therapeutic modality to improve efficacy of 5-FU-based chemotherapy, possibly by inhibiting autophagy-dependent resistance to chemotherapy.
The Journal of Allergy and Clinical Immunology | 2003
Kazushige Kawai; Nelson H. Tsuno; Joji Kitayama; Yurai Okaji; Kentaro Yazawa; Masahiro Asakage; Nobukazu Hori; Toshiaki Watanabe; Koki Takahashi; Hirokazu Nagawa
BACKGROUND Epigallocatechin gallate (EGCG), the major component of tea polyphenol, has been reported to have various physiologic modulatory activities. Several reports also have shown that catechin has a protective effect against HIV infection, part of which is mediated by inhibiting virions to bind to the target cell surface. OBJECTIVE We investigated the effect of EGCG on the expression of CD4 molecules and on its ability to bind gp120, an envelope protein of HIV-1. METHODS Peripheral blood CD4+ T cells were incubated in the presence of EGCG, and the expression of CD4 was evaluated by means of flow cytometry. The effect of EGCG on the antibody binding to CD4 was investigated by using a sandwich ELISA, and the effect on the gp120 binding to CD4 was analyzed by means of flow cytometry. RESULTS EGCG efficiently inhibited binding of anti-CD4 antibody to its corresponding antigen. This effect was mediated by the direct binding of EGCG to the CD4 molecule, with consequent inhibition of antibody binding, as well as gp120 binding. CONCLUSION The present results suggest a potential preventive effect of EGCG on HIV-1 infection by modulating binding to CD4.
Journal of Immunology | 2004
Daisuke Sakurai; Naoyuki Tsuchiya; Akihiro Yamaguchi; Yurai Okaji; Nelson H. Tsuno; Tetsuji Kobata; Koki Takahashi; Katsushi Tokunaga
Angiogenesis plays a pivotal role in the aggressive proliferation of synovial cells in rheumatoid arthritis. We have previously reported the overexpression of inhibitor of DNA binding/differentiation (Id) in the endothelial cells within the synovial tissues of rheumatoid arthritis. In this study, we investigated the role of Id in inflammation and angiogenesis in an in vitro model using HUVECs. Vascular endothelial growth factor (VEGF) and TGFβ induced the expression of Id1 and Id3 in HUVECs. Forced expression of Id induced proliferative activity in HUVECs accompanied by down-regulation of p16INK4a. Overexpression of Id enhanced expression of ICAM-1 and E-selectin, and induced angiogenic processes such as transmigration, matrix metalloproteinase-2 and -9 expression, and tube formation. In contrast, knockdown of Id1 and Id3 with RNA interference abolished proliferation, activation, and angiogenic processes of HUVECs induced by VEGF. These results indicated that Id plays a crucial role in VEGF-induced signals of endothelial cells by causing activation and potentiation of angiogenic processes. Based on these findings, it was proposed that inhibition of expression and/or function of Id1 and Id3 may potentially be of therapeutic value for conditions associated with pathological angiogenesis.
Cancer Science | 2004
Yurai Okaji; Nelson H. Tsuno; Joji Kitayama; Shinsuke Saito; Tsuyoshi Takahashi; Kazushige Kawai; Kentaro Yazawa; Masahiro Asakage; Nobukazu Hori; Toshiaki Watanabe; Yoichi Shibata; Koki Takahashi; Hirokazu Nagawa
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 Colon26. The effect of autologous HSEs was more pronounced than that of xenogeneic human umbilical vein endothelial cells (HU‐VECs), 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. (Cancer Sci 2004; 95: 85–90)
Journal of Surgical Research | 2009
Jun Yamada; Nelson H. Tsuno; Joji Kitayama; Takeshi Tsuchiya; Satomi Yoneyama; Masahiro Asakage; Yurai Okaji; Yasutaka Shuno; Takeshi Nishikawa; Junichiro Tanaka; Koki Takahashi; Hirokazu Nagawa
BACKGROUND Zoledronic acid (ZOL) is clinically available for the treatment of skeletal complications. In preclinical studies, strong anti-cancer activities against breast cancer, prostate cancer, and leukemia were reported. It also inhibited the proliferation of cultured human endothelial cells, suggestive of an anti-angiogenic activity. Since ZOL has the tendency to accumulate in bone, we investigated the effect of ZOL on endothelial progenitor cells (EPCs), which originate from the bone marrow, and play important roles in angiogenesis. MATERIALS AND METHODS Human peripheral blood mononuclear cells were cultured for 7 d to differentiate into EPCs. Cells were treated without/with ZOL or with geranylgeraniol (GGOH). Their endothelial phenotype was confirmed by the expression of CD144 and vascular endothelial growth factor receptor 2 and the tube-like formation ability on Matrigel (Becton Dickinson, Bedford, MA). Annexin V/propidium iodide staining was used to analyze apoptosis. RESULTS ZOL treatment, even at low doses, from d 2 to 7 of culture resulted in impaired EPC differentiation and could be restored by co-treatment with GGOH. On the other hand, treatment of putative EPCs with ZOL at concentrations higher than 10 mum resulted in induction of apoptosis. CONCLUSION ZOL dose-dependently inhibited the differentiation of EPCs, the effect being observed even at low drug levels. At high concentrations, ZOL also induced the apoptotic death of putative EPCs. Since GGOH restored the inhibitory effect of ZOL on EPCs differentiation, the effect of ZOL appears to be dependent on the inhibition of prenylation of small-G-proteins. From these findings, we conclude that ZOL could be a potential anticancer agent by inhibiting angiogenesis.
Angiogenesis | 2006
Masahiro Asakage; Nelson H. Tsuno; Joji Kitayama; Takeshi Tsuchiya; Satomi Yoneyama; Jun Yamada; Yurai Okaji; Shoichi Kaisaki; Takuya Osada; Koki Takahashi; Hirokazu Nagawa
Sulforaphane (SUL), one of the isothiocyanates (ITCs), has recently been focused due to its inhibitory effects on tumor cell growth in vitro and in vivo, which is dependent on the direct effect on cancer cells. In the present study, we aimed to investigate the potential anti-angiogenic effect of SUL and its mechanism of action. Using the human umbilical vein endothelial cells (HUVECs) as a model of angiogenesis, we investigated the effect of SUL on the various steps of angiogenesis, including the proliferation of endothelial cells, tubular formation, and matrix metalloproteinase (MMP) production. Sulforaphane induced a dose-dependent decrease in the proliferative activity of endothelial cells, which was dependent on cell apoptosis. Also SUL inhibited tube formation on matrigel, but did not affect MMP production. The present results demonstrate the anti-angiogenic activity of SUL and its potential use as an anti-cancer drug is suggested.
Cancer Science | 2005
Takeshi Tsuchiya; Yurai Okaji; Nelson H. Tsuno; Daisuke Sakurai; Naoyuki Tsuchiya; Kazushige Kawai; Kentaro Yazawa; Masahiro Asakage; Jun Yamada; Satomi Yoneyama; Joji Kitayama; Takuya Osada; Toshiaki Watanabe; Katsushi Tokunaga; Koki Takahashi; Hirokazu Nagawa
Inhibitor of DNA binding (Id) proteins are essential for cell differentiation, proliferation, migration, invasion and angiogenesis. Recently, they have been shown to correlate with less differentiated phenotypes, high malignant potential and poor clinical outcome in various kinds of tumors. In an attempt to develop new strategies for the treatment of peritoneal metastasis of gastric cancer, we prepared an Id1, 3 double‐knockdown gastric cancer cell line, MKN45, by RNA interference and investigated its effects on the development of metastatic nodules in the peritoneal cavity. Both cell proliferation and migration capabilities were decreased in Id1, 3 double‐knockdown cells, as was their ability to bind to laminin, which could be explained by the decreased expression of integrin α6. These are important steps in the metastatic process. In a mouse model, the number of peritoneal metastatic nodules formed by Id1, 3 double‐knockdown cells was reduced compared to mock‐transfected control cells, as was the size of individual tumors. In this study, we clearly demonstrated that Id1, 3 double‐knockdown significantly impaired the ability of gastric cancer cells to form peritoneal metastasis. Id should be considered an ideal target for the treatment and prevention of gastric cancer, and RNA interference is an attractive and promising strategy to achieve it. (Cancer Sci 2005; 96: 784–790)
Journal of Gastroenterology | 2003
Shinsuke Saito; Nelson H. Tsuno; Eiji Sunami; Nobukazu Hori; Joji Kitayama; Shinsuke Kazama; Yurai Okaji; Kazushige Kawai; Takamitsu Kanazawa; Toshiaki Watanabe; Yoichi Shibata; Hirokazu Nagawa
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 Crohns 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.
Cancer Science | 2005
Kentaro Yazawa; Nelson H. Tsuno; Joji Kitayama; Kazushige Kawai; Yurai Okaji; Masahiro Asakage; Eiji Sunami; Shoichi Kaisaki; Nobukazu Hori; Toshiaki Watanabe; Koki Takahashi; Hirokazu Nagawa
High level expression of cyclooxygenase (COX)‐2 is reported in 80–90% of colorectal adenocarcinomas. In the recent years, selective inhibitors of COX‐2 have been developed, and are shown to effectively protect against cancer development and progression. Colon cancer cells, as well as the epithelial cells in general, are dependent on appropriate interactions with the extracellular matrix (ECM) proteins to achieve a number of important functions, such as proliferation, differentiation, invasion and survival. These interactions are mediated via a family of cell‐surface receptors called integrins, which interact with cytoskeletal proteins on the cytoplasmic side of the plasma membrane and thereby provide a link between the ECM and the cytoskeleton. In the present study, a high‐COX‐2 (high level COX‐2 expression) colon cancer cell line, HT‐29, and a low‐COX‐2 (low level COX‐2 expression), DLD‐1, were used to investigate the anticolon cancer effect of the selective COX‐2 inhibitor, JTE‐522. Moreover, to clarify its mechanisms of action, we focused especially on the ability to adhere to and to migrate on ECM. We could clearly demonstrate that, in addition to the decrease of the proliferative activity, JTE‐522 caused a dose‐dependent decrease in both the ability of colon cancer cells to adhere to and to migrate on ECM. These effects were, at least in part, dependent on the down‐regulation of β1‐integrin expression, which was evident in HT‐29, the high‐COX‐2 colon cancer cells, but not the low‐COX‐2, DLD‐1. In addition, prostaglandin E2 almost completely reversed the effect of JTE‐522, strongly suggesting the involvement of a COX‐2‐dependent pathway. In conclusion, for the first time, we could demonstrate the down‐regulation of β1 integrin caused by COX‐2 inhibition, with consequent impairment of the ability of cancer cells to adhere to and to migrate on ECM, which are crucial steps for cancer metastases to develop. (Cancer Sci 2005; 96: 93–99)
Journal of Surgical Research | 2010
Yasutaka Shuno; Nelson H. Tsuno; Yurai Okaji; Takeshi Tsuchiya; Daisuke Sakurai; Takeshi Nishikawa; Naoyuki Yoshikawa; Kazuhito Sasaki; Kumiko Hongo; Giichiro Tsurita; Eiji Sunami; Joji Kitayama; Katsushi Tokunaga; Koki Takahashi; Hirokazu Nagawa
BACKGROUND The Id (inhibitor of DNA binding/differentiation) proteins belong to the helix-loop-helix transcriptional regulatory factors, and play important roles in tumor development. Previously, we and others have shown that targeting Id in tumor cells could have important clinical implications. In the present study, we aimed to evaluate the effects of Id inhibition in human pancreatic cancer cells. MATERIALS AND METHODS Id1 and Id3 were stably double-knockdown in human pancreatic cancer cell line MIA-Paca2 by means of RNA interference. Expression of Id and integrins were analyzed by flow-cytometry. Cell proliferation was evaluated by MTS assay. Migration was measured by wound closure assay. Adhesion assay was performed to evaluate binding capacity for different extracellular matrix proteins. Finally, in vivo properties of tumor cells were observed in a mouse model of peritoneal metastasis. RESULTS Id1/Id3 double-knockdown resulted in decreased ability of pancreatic cancer cells to proliferate and migrate. In addition, Id1/Id3 double-knockdown caused decreased expression of integrins alpha3, alpha6, and beta1, and consequently reduced adhesion of tumor cells to laminin. Finally, peritoneal metastases of Id1/Id3 double-knockdown tumor cells were significantly reduced. CONCLUSIONS We concluded that the Id proteins play a pivotal role in the development of peritoneal metastasis of pancreatic cancer, and consequently, their targeting would be a novel strategy for the prevention and treatment of pancreatic cancer.