Masahiro Asakage

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.

Prospective Randomized Trial Comparing Billroth I and Roux-en-Y Procedures after Distal Gastrectomy for Gastric Carcinoma

To determine the clinical efficacy of Roux-en-Y reconstruction (RY) after distal gastrectomy, we compared postoperative outcomes of patients who underwent RY or conventional Billroth I reconstruction (B-I). A total of 50 patients were prospectively randomized to either B-I or RY reconstruction, and complications, postoperative course, and nutritional status were compared. Bile reflux and inflammation in the remnant stomach and lower esophagus were evaluated by postoperative follow-up endoscopy at 6 months. Operative time and blood loss as well as postoperative nutrition did not show significant differences between the two groups. As anticipated, 5 of 24 patients with RY reconstruction developed gastrojejunal stasis in the early postoperative period, which led to a longer postoperative hospital stay as compared with the B-I group (mean ± S.D; B-I; 19.0 ± 6.2, RY; 31.8 ± 21.7 days) (P < 0.05). Endoscopic examination revealed that the frequency of bile reflux (P < 0.01) and degree of inflammation in the remnant stomach (P < 0.05) were less in the RY group than in the B-I group. However, inflammatory findings in the lower esophagus were observed in 7 (27%) of B-I, and 8 (35%) of the RY group, suggesting that late phase esophagitis was not improved in the RY group. Roux-en-Y reconstruction was effective in preventing duodenogastric reflux and resulting gastritis, but it did not prevent esophagitis. Because RY reconstruction induces the frequent complication of Roux-en-Y stasis, causing longer postoperative hospital stay, this method has limited advantages over B-I anastomosis after distal gastrectomy.

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)

Anti-angiogenic property of zoledronic acid by inhibition of endothelial progenitor cell differentiation.

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.

Sulforaphane induces inhibition of human umbilical vein endothelial cells proliferation by apoptosis

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.

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)

Pharmacological Synergism Between Cannabinoids and Paclitaxel in Gastric Cancer Cell Lines

Orally applicable Delta9-tetrahydrocannabinol and its synthetic derivatives have been used as antiemetic drugs during chemotherapy in cancer patients. However, it is not well known how cannabinoids influence the effects of chemotherapeutic agents on malignant tumors. In this study, we investigated how the endogenous cannabinoid anandamide (AEA) changes the effect of paclitaxel on gastric cancer cell lines. In the human gastric cancer cell line, HGC-27, which express cannabinoid receptor 1 (CB1), AEA stimulated proliferation at concentrations under 1 microM, while it strongly suppressed proliferation through the induction of apoptosis at 10 microM. This bimodal effect was reproduced by a selective CB1 agonist, arachidonyl-2-chloroethylamide, although the effects were less marked. When AEA was used with paclitaxel, AEA at 10 microM synergistically enhanced the cytotoxic effect of paclitaxel, whereas it showed no significant effect at lower concentrations. Flow cytometric analysis revealed that addition of 10 microM AEA synergistically enhanced paclitaxel-induced apoptosis, possibly through the activation of caspase-3, -8, and -9. Our results suggest that cannabinoids could be a good palliative agent for cancer patients receiving paclitaxel.

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.