Nobukazu Hori

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)

Extensive mesenteric vein and portal vein thrombosis successfully treated by thrombolysis and anticoagulation

Abstract Mesenteric vein thrombosis is generally difficult to diagnose and can be fatal. A case of extensive thrombosis of the mesenteric and portal veins was diagnosed early and successfully treated in a 26‐year‐old man with Down syndrome who was admitted to hospital because of abdominal pain, severe nausea and high fever. Ultrasonography revealed moderate ascites, and there was minimal flow in the portal vein (PV) on the Doppler examination. Computed tomography (CT) showed remarkable thickening of the walls of the small intestine and extensive thrombosis of the mesenteric, portal and splenic veins. Because neither intestinal infarction nor peritonitis was seen, combined thrombolysis and anticoagulation therapy without surgical treatment was chosen. Urokinase was administered intravenously and later through a catheter in the superior mesenteric artery. Heparin and antibiotics were given concomitantly. The patients symptoms and clinical data improved gradually. After 10 days, CT revealed that collateral veins had developed and the thrombi in the distal portions of the mesenteric veins had dissolved, although the main trunk of the PV had not recanalized. The only risk factor of thrombosis that was detected was decreased protein S activity.

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 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.

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)

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.

Primary malignant melanoma of the esophagus treated by esophagectomy and adjuvant dendritic-cell therapy

To the Editor: Malignant melanoma is a typical cutaneous tumor, arising from melanocytes. Primary malignant melanoma of the esophagus (PMME) is uncommon, comprising from 0.1% to 0.2% of all malignant esophageal tumors. PMME is characteristically aggressive and disseminates early via the bloodstream and lymphatics.1 Here, we report the first case of surgically treated PMME with adjuvant dendritic-cell (DC) therapy. The patient has been free from any signs of recurrence for 2.5 years after the surgery. A 56-year-old man was investigated because he had vomited blood with clots. Physical examinations revealed no pigmented lesions of the skin, rectum, eyes, or elsewhere that were suspicious for melanoma. Esophagogastroscopy showed an ulcerated tumor, sited 27–32 cm from the incisors (Fig. 1a,b). On the biopsy specimen, the lesion was identified as a malignant melanoma. Computed tomography (CT) showed no evidence of distant metastasis. On July 9, 2001, subtotal esophagectomy and lymph node dissection was performed through a retrosternal route. The patient’s postoperative course was uneventful. The surgical specimen contained an ulcerative tumor, which showed a black area under the normal mucosa on the margin of tumor. Histologically, the tumor cells had invaded to the muscularis propia, and the resection margins were free of tumor. Tumor cells at the edge of the tumor contained abundant melanin granules, and there were melanophages in the matrix (Fig. 2a,b). There was no lymph node metastasis. Immunohistochemical staining was positive for antibodies against S-100 and HMB-45 (Fig. 2c,d) and negative for cytokeratin, findings that were consistent with malignant melanoma. The diagnosis of R0-resected PMME, analogous to a pT2N0M0 stage carcinoma was verified. PMME has extremely high malignant potential, with a mean survival of 14 months after radical resection, and with metastasis or recurrence often being observed even in the early stage.2,3 Therefore, we performed DC therapy as adjuvant therapy. The DC therapy was performed as described previously.4 Briefly, the DC therapy had been approved by the Ethics Committee of the University of Tokyo, and written informed consent was obtained from the patient before the DC therapy was started. DCs were generated from peripheral monocytes collected by leukapheresis. The monocytes were cultured with 1000 IU/ml granulocyte-macrophage (GM)-colony-stimulating factor (CSF) and 500 IU/ml interleukin (IL)-4 for 7 days, with pulsation of autologous tumor lysates. The patient received four intradermal infections, of 3 or 4 107 DCs, weekly. At 2.5 years after the operation, the patient is healthy, without any sign of relapse on chest or abdominal computed tomography, or as shown by tumor markers. The main treatment of PMME is supposed to be surgical resection. However, as stated above, the mean survival after radical resection is 14 months, and the overall 5-year survival rate after radical surgical resection is reported to be 4.2%;1 the efficacy of adjuvant therapy for PMME has never been clearly demonstrated. Therefore, effective adjuvant therapy should be explored, even at a relatively early stage of the disease. The place of chemotherapy and radiotherapy in the treatment of PMME is unclear. However, chemotherapy and radiotherapy alone in the treatment of PMME generally does not show real effectiveness and, thus, it appears that these treatments do not have a major role in the management of this tumor.1 DCs are highly efficient antigen-presenting cells that play a crucial role in the initiation of the T-lymphocyte-dependent specific immune response.5 The clinical usage of autologous DCs in the treatment of cutaneous malignant melanoma, glioblastoma, renal cell carcinoma, prostate cancer, and B-cell lymphoma has been reported, with promising results.6 In particular, in the first trial using DCs, in 16 patients with advanced metastatic melanoma, objective clinical responses were obtained in 5 of the 16 patients, including two complete and three partial remissions.7 No significant side effect has been reported. These reports encouraged us to use DCs as postoperative adjuvant therapy for our patient with PMME, and this brought about a 2.5-year tumor-free period. Our result indicates that DC therapy is a safe and promising approach as adjuvant therapy for PMME, which is often a fatal disease.