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Atsushi Togawa

Publications and source records attributed to Atsushi Togawa.

12 recordsLinked to original sources
PubMed2006

Defective chemokine-directed lymphocyte migration and development in the absence of Rho guanosine diphosphate-dissociation inhibitors alpha and beta.

Rho family small GTP-binding proteins, including Rho, Rac, and Cdc42, are key determinants of cell movement and actin-dependent cytoskeletal morphogenesis. Rho GDP-dissociation inhibitor (GDI) alpha and Rho GDIbeta (or D4/Ly-GDI), closely related regulators for Rho proteins, are both expressed in hemopoietic cell lineages. Nevertheless, the functional contributions of Rho GDIs remain poorly understood in vivo. In this study, we report that combined disruption of both the Rho GDIalpha and Rho GDIbeta genes in mice resulted in reduction of marginal zone B cells in the spleen, retention of mature T cells in the thymic medulla, and a marked increase in eosinophil numbers. Furthermore, these mice showed lower CD3 expression and impaired CD3-mediated proliferation of T cells. While B cells showed slightly enhanced chemotactic migration in response to CXCL12, peripheral T cells showed markedly reduced chemotactic migration in response to CCL21 and CCL19 associated with decreased receptor levels of CCR7. Overall, Rho protein levels were reduced in the bone marrow, spleen, and thymus but sustained activation of the residual part of RhoA, Rac1, and Cdc42 was detected mainly in the bone marrow and spleen. Rho GDIalpha and Rho GDIbeta thus play synergistic roles in lymphocyte migration and development by modulating activation cycle of the Rho proteins in a lymphoid organ-specific manner.

Animals↗
PubMed2006

Lipocalin 2-deficient mice exhibit increased sensitivity to Escherichia coli infection but not to ischemia-reperfusion injury.

Diverse functions have been reported for lipocalin 2. To investigate these functions in vivo, we generated gene-targeted lipocalin 2-deficient mice (Lcn2-/- mice). In vitro studies have suggested that lipocalin 2 is important for cellular apoptosis induced by IL-3 withdrawal, and for the induction of kidney differentiation during embryogenesis. Analysis of Lcn2-/- mice showed normal cell death upon IL-3 withdrawal and normal kidney development. However, we found that Lcn2-/- mice exhibited an increased susceptibility to bacterial infections, in keeping with the proposed function of lipocalin 2 in iron sequestration. Neutrophils isolated from Lcn2-/- mice showed significantly less bacteriostatic activity compared with WT controls. The bacteriostatic property of the WT neutrophils was abolished by the addition of exogenous iron, indicating that the main function of lipocalin 2 in the antibacterial innate immune response is to limit this essential element. Another important function ascribed to lipocalin 2 has been its protective role against kidney ischemia-reperfusion injury. We analyzed Lcn2-/- mice using a mouse model for severe renal failure and could not detect any significant differences compared with their WT littermates.

Acute-Phase Proteins↗
PubMed2006

A phase II study of VEPA/FEPP chemotherapy for aggressive lymphoma in elderly patients: Japan Clinical Oncology Group Study JCOG9203.

The Lymphoma Study Group (LSG) of the Japan Clinical Oncology Group conducted a phase II trial of LSG12 therapy for 45 elderly patients with aggressive lymphoma to clarify whether LSG12 reduces severe infection without lowering the complete response (CR) rate in comparison with LSG4. LSG12, which consisted of a regimen of vincristine, cyclophosphamide, prednisolone, doxorubicin, vindesine, etoposide, and procarbazine (VEPA/FEPP), excluded bleomycin and methotrexate of LSG4 therapy, reduced the dosages of doxorubicin and cyclophosphamide, and increased etoposide and procarbazine dosages instead. Inclusion criteria consisted of a patient age of 70 to 75 years, a World Health Organization performance status of 0 to 2, and acceptable organ function. The treatment was completed in 47% of the patients and terminated early for disease progression in 20% and for toxicity in 16%. The CR rate was 60% (95% confidence interval [CI], 44%-74%). The 5-year overall survival (OS) rate was 42% (95% CI, 27%-57%), and the median OS time was 4.3 years. Leukopenia of grade 3 to 4 occurred in 98% of the patients, and severe infection occurred in 9%. Eight patients with hepatitis C virus (HCV) antibody showed no severe hepatic toxicity and had a better CR or OS rate than the 37 HCV-negative patients. Although the outcomes of LSG12 met our expectations with a reduction in severe infection and equivalent CR and OS outcomes compared with LSG4 and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone), the possibility of a regimen more beneficial than LSG12 for aggressive lymphoma in the elderly patient should be explored because of frequent hematologic toxicity and poor compliance in LSG12.

Aged↗
PubMed2004

High-dose chemotherapy and autologous peripheral blood stem cell transplantation in high-risk multiple myeloma.

We compared the effect of high-dose therapy together with autologous peripheral blood stem cell transplantation (autoPBSCT) in 60 patients with multiple myeloma (MM) with 90 patients who underwent conventional chemotherapy. We scored the prognostic factors according to our reported classification system that includes measurements of serum albumin, serum beta-2-microglobulin, and morphology of myeloma cells selected by multivariate analysis. We separated the patients into three risk groups at stratification level I (low, intermediate and high) and into two risk groups at stratification level II (low and high). AutoPBSCT tended to be as effective for high, as for low-risk patients in level I, and was obviously as helpful for high, as for low-risk patients in stratification II. In conclusion, high-risk patients with MM should be treated with high-dose therapy accompanied with autoPBSCT like low-risk patients.

Adult↗
PubMed2004

[Thalidomide treatment of patients with refractory myeloma in the institutes participating in the Japan Myeloma Study Group].

Thalidomide was used in 73 patients with refractory myeloma in 15 of 45 institutes participating in the Japan Myeloma Study Group. The mean age and male/female ratio were 63.8 years and 0.92 (35/38), respectively. Thirty-four patients (47%) were treated with only thalidomide, 27 patients (37%) were treated with thalidomide and steroids, and 12 (16%) were treated with thalidomide and chemotherapy. The mean initial, maximum, and maintenances dose of thalidomide were 111.0, 204.8, and 163.0 mg/day, respectively. Almost all of the patients were maintained on low-dose thalidomide between 100-200 mg/day. Complete, near complete and partial response was obtained in 31 patients (42.5%). The progression-free and overall survivals after thalidomide therapy were 9.8 and 21.3 months, respectively. The most common adverse effects were gastrointestinal disturbance, peripheral neuropathy, psychological signs, and skin eruption. In contrast to reports from Europe and America, no deep vein thrombosis was observed in this study. On the other hand, leukopenia was relatively frequently observed, and might be recognized as a serious adverse effect in myeloma patients. In conclusion, low-dose thalidomide is a useful and safe tool for the treatment of refractory myeloma.

Female↗
PubMed2003

Cyclic phosphatidic acid inhibits RhoA-mediated autophosphorylation of FAK at Tyr-397 and subsequent tumor-cell invasion.

We demonstrated previously that rat ascites hepatoma MM1 cells require both lysophosphatidic acid (LPA) and fibronectin (FN) for phagokinetic motility and transcellular migration and that these events are regulated through the RhoA-ROCK pathway and tyrosine phosphorylation of proteins including focal adhesion kinase (FAK). Moreover, we reported that palmitoyl-cyclic phosphatidic acid (Pal-cPA), a structural analogue of LPA, inhibits LPA-induced migration of MM1 cells and experimental metastasis of B16 murine melanoma cells. However, the molecular mechanisms of action of Pal-cPA remains to be clarified. To examine this, total cellular lysates after stimulation with LPA or FN were subjected to time-course immunoblot analysis with anti-phophotyrosine and anti-pY397-FAK antibodies. Tyrosine-phosphorylation of FAK especially at Tyr-397 was obviously persistent after stimulation with LPA + FN compared to after stimulation with LPA alone. This persistent phosphorylation was necessary for MM1 cell migration and inhibited by Pal-cPA as by C3 exoenzyme Rho inhibitor. RhoA activity (GTP-bound RhoA) was also measured by the pull down assay using the Rho binding domain of Rhotekin. LPA-induced RhoA-activation of MM1 cells was completely inhibited by Pal-cPA. Moreover, we demonstrated that autophosphorylation of FAK at Tyr-397, downstream of RhoA, contributed to formation of focal adhesions and was critical in LPA-induced MM1 cell migration by developing autophosphorylation-deficient (Y397F) FAK-transfectants. Collectively, Pal-cPA hampered LPA-induced morphological changes and transcellular migration of MM1 cells through downregulating active RhoA and inhibiting its downstream events including autophosphorylation of FAK. Pal-cPA also inhibited endogenous (LPA-independent) activation of RhoA in human fibrosarcoma HT-1080 cells. Pal-cPA may potentially provide a new therapy for the treatment of cancer invasion and metastasis.

Animals↗
PubMed2002

Different cytokines induce surface lymphotoxin-alphabeta on IL-7 receptor-alpha cells that differentially engender lymph nodes and Peyer's patches.

The formation of lymph nodes (LN) and Peyer's patches (PP) can be distinguished by the requirement of RANK for LN but not IL-7R(alpha), which is essential for PP development. However, lymphotoxin-alphabeta (LT(alpha)beta) signaling is required for both organs. The cellular basis underlying this dichotomy was revealed by the finding that the fetal IL-7R(alpha)(+) population responded equally well to IL-7 and RANKL to express LT(alpha)beta. IL-7R(alpha)(+) cells harvested from TRAF6(-/-) embryos expressed LTalphabeta in response to IL-7 but not RANKL, demonstrating that the RANK-TRAF6 signaling pathway regulates LT(alpha)beta expression in LN but not in PP. Soluble IL-7 administered to TRAF6(-/-) embryos was sufficient to restore LN genesis indicating the functional similarities of the IL-7R(alpha)(+) inducer cells for LN and PP genesis.

Animals↗
PubMed2002

Prognostic factors in elderly patients with acute myelogenous leukemia: a single center study in Japan.

We retrospectively analyzed data of 47 patients aged 60 years or older, hospitalized in our institution with the diagnosis of acute myelogenous leukemia (AML), and searched for prognostic factors. Induction with anthracyclines significantly correlated with better complete remission (CR) rate (P = 0.0016) and overall survival (OS) (P < 0.001). Another factor significantly affecting CR rate was higher age (> 70 years) (P = 0.042). Therapy-non-related factors predictive for shorter OS in univariate analyses were age older than 70 years (P = 0.003), percentage of blasts in bone marrow more than 80% (P = 0.048), serum lactate dehydrogenase level higher than 250 U l(-1) (P = 0.032). In stepwise cox proportional hazard regression model, all the four factors predictive for poor OS remained to be independently and significantly prognostic for shorter OS. Only two patients receiving anthracyclines died within 30 days and the frequency was not different from that in patients not receiving anthracyclines. The use of anthracyclines as induction therapy is recommended even in the elderly patients.

Age Factors↗
PubMedDate not supplied

Sustained tyrosine-phosphorylation of FAK through Rho-dependent adhesion to fibronectin is essential for cancer cell migration.

BACKGROUND: Co-stimulation with lysophosphatidic acid (LPA) and fibronectin (FN) is essential for migration of rat ascites hepatoma MMI cells. We examined the roles of LPA and FN in Rho-FAK pathway to migration. MATERIALS AND METHODS: We evaluated the morphology, phagokinetic motility and the status of Rho activation and tyrosine-phosphorylation of FAK after stimulation of MMI or HT-1080 cells with LPA + FN or each alone. RESULTS: On FN-coated dishes without LPA, MM1 cells could not migrate and harbored undetectable levels of activated RhoA. Stimulation with LPA + FN enabled the MM1 cells to migrate and bear active RhoA and sustained tyrosine-phosphorylation of FAK. To the contrary, HT-1080 cells could migrate and harbored a significant amount of active RhoA accompanied by sustained tyrosine-phosphorylation of FAK even without LPA. CONCLUSION: Rho-dependent adhesion to FN leading to sustained tyrosine-phosphorylation of FAK is essential for cancer cell migration.

Animals↗