Kentaro Yazawa

Epigallocatechin gallate, the main component of tea polyphenol, binds to CD4 and interferes with gp120 binding

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.

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 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)

Targeting Id1 and Id3 inhibits peritoneal metastasis of gastric cancer

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)

Selective inhibition of cyclooxygenase‐2 inhibits colon cancer cell adhesion to extracellular matrix by decreased expression of β1 integrin

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)

Early-outgrowth of endothelial progenitor cells can function as antigen-presenting cells

Endothelial progenitor cells (EPCs) have been recently found to exist circulating in peripheral blood of adults, and home to sites of neovascularization in peripheral tissues. They can also be differentiated from peripheral blood mononuclear cells (PBMNCs). In tumor tissues, EPCs are found in highly vascularized lesions. Few reports exist in the literature concerning the characteristics of EPCs, especially related to their surface antigen expressions, except for endothelial markers. Here, we aimed to investigate the surface expression of differentiation markers, and the functional activities of early-outgrowth of EPCs (EO-EPCs), especially focusing on their antigen-presenting ability. EO-EPCs were generated from PBMNCs, by culture in the presence of angiogenic factors. These EO-EPCs had the morphological and functional features of endothelial cells and, additionally, they shared antigen-presenting ability. They induced the proliferation of allogeneic lymphocytes in a mixed-lymphocyte reaction, and could generate cytotoxic lymphocytes, with the ability to lyze tumor cells in an antigen-specific manner. The antigen-presenting ability of EO-EPCs, however, was weaker than that of monocyte-derived dendritic cells, but stronger than peripheral blood monocytes. Since EO-EPCs play an important role in the development of tumor angiogenesis, targeting EPCs would be an effective anti-angiogenic strategy. Alternatively, due to their antigen-presenting ability, EO-EPCs can be used as the effectors of anti-tumor immunotherapy. Since they share endothelial antigens, the activation of a cellular immunity against angiogenic vessels can be expected. In conclusion, EO-EPCs should be an interesting alternative for the development of new therapeutic strategies to combat cancer, either as the effectors or as the targets of cancer immunotherapy.

Selective inhibition of cyclooxygenase (COX)-2 inhibits endothelial cell proliferation by induction of cell cycle arrest

High‐level expression of cyclooxygenase (COX)‐2 is reported in 80–90% of colorectal adenocarcinomas. Selective inhibition of COX‐2 was shown to reduce colorectal tumorigenesis in different models of carcinogenesis and to prevent metastasis in xenograft tumor models, as well as to suppress in vitro induced angiogenesis. Recently, COX‐2 was reported to be expressed not only in malignant epithelial cells, but also in the neovasculature that feeds the tumor in a variety of solid human cancers. Thus, one of the possible mechanisms by which selective COX‐2 inhibitor reduces tumor growth and metastasis is through inhibition of tumor angiogenesis. Although a report suggested a possible role of endothelial COX‐1 in the process of angiogenesis, in a recent study, the selective inhibition of COX‐2 was shown to strongly inhibit angiogenesis by inducing endothelial cell (EC) apoptosis. In the present study, using human umbilical vein endothelial cells (HUVECs) as a model of angiogenesis, we investigated the potential antiangiogenic effect of the selective COX‐2 inhibitor and its mechanism of action, and clearly demonstrated that selective inhibition of COX‐2 caused a dose‐dependent decrease in the proliferative activity of ECs, as well as an inhibition of capillary‐like tube formation. The inhibitory effect on EC proliferation was dependent on the cell cycle arrest to the G1 phase and not on cell apoptosis.

FOLFOX as Adjuvant Chemotherapy after Curative Resection of Distant Metastases in Patients with Colorectal Cancer

Objectives: The prophylactic effect of FOLFOX regimen, a standard regimen for unresectable colorectal cancer (CRC), was investigated in the adjuvant setting of CRC cases with distant metastases. Methods: The study population included 116 CRC patients with synchronous metastases and 91 patients with metachronous metastases who had undergone curative operation in our hospital between 2000 and 2009. Clinicopathological parameters of CRC, postoperative chemotherapeutic regimen, recurrence rate, and relapse-free survival (RFS) were analyzed retrospectively. Results: After resection of CRC and synchronous metastases, 53 (84%) out of 63 patients without chemotherapy, and 38 (83%) out of 46 that received 5-fluorouracil (5-FU) alone or with leucovorin (LV) developed recurrent tumors. By contrast, only 1 (17%) among 6 patients who underwent FOLFOX treatment showed recurrence. The FOLFOX group exhibited significantly improved RFS as compared to the 5-FU (+ LV) or surgery-alone group (p = 0.03, p = 0.007, respectively). On the other hand, in patients with metachronous metastases, tumor-relapse rate and RFS were not significantly influenced by post-metastasectomy therapies. Conclusions: In this retrospective analysis, the adjuvant administration of FOLFOX appeared to reduce the risk of relapse in a small group of CRC patients with synchronous metastases. Prospective randomized trials will be required to confirm the benefits of this management strategy.

Anti-angiogenic properties of plaunotol

We have investigated a potential anti-angiogenic effect of plaunotol, an extract from the leaves of Plau-noi, in an angiogenesis model consisting of human umbilical vein endothelial cells (HUVECs). Plaunotol inhibited the proliferative activity of HUVECs in a dose-dependent manner. In addition, it caused a remarkable decrease of the ability of HUVECs to adhere and spread on gelatin and vitronectin, but not fibronectin. Tube-like formation in Matrigel was also inhibited in a dose-dependent way. These results strongly suggest the specific inhibition of integrin &agr;v&bgr;3 to be the main event of plaunotol-induced suppression of angiogenesis. The &agr;v&bgr;3 antagonists are known to be potent inhibitors of tumor angiogenesis and plaunotol, by causing the functional inhibition of &agr;v&bgr;3, should be considered a promising new anti-angiogenic drug.

Endoscopic Resection of an Inflammatory Fibroid Polyp in the Cecum: A Case Report

Introduction: Inflammatory fibroid polyps (IFPs) are rare, benign lesions of the gastrointestinal tract. Their occurrence in the colon is rare. They are often surgically resected for various reasons. Case presentation: A 60-year-old woman presented to our institution. She had a history of gynecologic surgery for cervical cancer at 37 years of age. Colonoscopy was performed by a local doctor and a type I tumor on Bauhin’s valve was suspected. Colonoscopy performed by us revealed a pedunculated polypoid tumor with a 20-mm head that was found to have a long stalk in the cecum. It was inferred that the stalk was entering and exiting through the valve since submucosal bleeding was observed. Polypectomy was performed. The histopathological diagnosis was IFP. Colonoscopy performed after 6 months showed no polyp recurrence. Discussion: According to previous reports, the treatment of colonic IFP was surgical in 58% of cases and endoscopic resection was performed in only 23% of cases. The decision to perform surgery was based on various factors, such as polyp size and position, difficulty in diagnosis by biopsy, and patient symptoms. In the present case, we could successfully perform polypectomy before the appearance of symptoms. Endoscopic resection seems to be an appropriate treatment approach due to the benign nature of IFP. The etiology of IFP remains unknown. Conclusion: The decision to perform surgery or endoscopic resection should be done on a case-by-case basis, but we think that a favorable increase in the number of endoscopic resections will occur in the future.

Abdominal CT-aided diagnosis of acute appendicitis in the presence of mobile cecum: A case report

Highlights • A mobile cecum is not an uncommon congenital anomaly.• Acute appendicitis in the presence of mobile caecum may present with atypical abdominal findings.• The presence of mobile cecum should be considered in the differential diagnosis of acute abdomen.• CT examination may be helpful in establishing the diagnosis in atypical presentation of acute appendicitis.• Abdominal computed tomography (CT) should be done in diagnosing acute abdomen.