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1.
J Nippon Med Sch ; 91(3): 339-346, 2024.
Article in English | MEDLINE | ID: mdl-38972747

ABSTRACT

Immune check point inhibitors (ICIs) have durable antitumor effects. However, autoimmune toxicities, termed immune-related adverse events, occur in some patients. We report a case of severe immune aplastic anemia (AA) in a patient with non-small cell lung cancer who was receiving atezolizumab with bevacizumab/carboplatin/paclitaxel. Although the cancer has not recurred, his bone marrow is depleted and he did not respond to immunosuppressive therapy. He has survived for 1.5 years with blood transfusions and infection control. Immune AA associated with ICIs is rare, and a treatment has not yet been established. This case report provides information on the management and treatment response of patients with AA caused by ICIs. Further studies should investigate the mechanism and pathogenesis of immune AA caused by ICIs.


Subject(s)
Anemia, Aplastic , Antibodies, Monoclonal, Humanized , Antineoplastic Combined Chemotherapy Protocols , Bevacizumab , Carboplatin , Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Paclitaxel , Humans , Carcinoma, Non-Small-Cell Lung/drug therapy , Anemia, Aplastic/chemically induced , Lung Neoplasms/drug therapy , Antibodies, Monoclonal, Humanized/adverse effects , Antibodies, Monoclonal, Humanized/administration & dosage , Male , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Carboplatin/administration & dosage , Carboplatin/adverse effects , Bevacizumab/adverse effects , Bevacizumab/administration & dosage , Paclitaxel/administration & dosage , Paclitaxel/adverse effects , Immune Checkpoint Inhibitors/adverse effects , Immune Checkpoint Inhibitors/administration & dosage , Treatment Outcome , Middle Aged , Severity of Illness Index
2.
Asia Pac J Clin Oncol ; 19(1): 136-148, 2023 Feb.
Article in English | MEDLINE | ID: mdl-35599446

ABSTRACT

AIM: The MEAM regimen consisting of ranimustine (MCNU), etoposide (ETP), cytarabine (Ara-C), and melphalan (MEL) is widely used before auto-peripheral blood stem cell transplantation (auto-PBSCT) for malignant lymphoma in Japan. The MEAM regimen generally consists of 200-400 mg/m2 for 4 days, but we decided to increase the dosage of Ara-C from the standard to 2 g/m2 for 2 days with the aim of increasing drug transferability to the central nervous system. We evaluate the safety and therapeutic efficacy of high-dose Ara-C MEAM therapy. METHODS: The high-dose Ara-C MEAM protocol consisted of MCNU 300 mg/m2 on day -7, ETP 200 mg/m2 on days -6, -5, -4, -3 and Ara-C 2 g/m2 on day -4 -3, and MEL 140 mg/m2 on day -2. We retrospectively analyzed 37 cases of malignant lymphoma at our institution between May 2014 and July 2020. RESULTS: All patients got engraftment and there were no cases of treatment-related mortality. In all cases, the 3-year overall survival (OS) and progression-free survival (PFS) after transplantation were 80.6% and 65.7%, respectively. Twenty-one cases of diffuse large B-cell lymphoma recurrence, for which there is proven usefulness of auto-PBSCT, showed good results after transplantation, with the 3-year OS and PFS after transplantation being 100% and 74.3%, respectively. CONCLUSION: The safety and efficacy of high-dose Ara-C MEAM therapy were demonstrated, but the expected therapeutic effect on central nervous system lesions could not be fully evaluated owing to the small number of cases.


Subject(s)
Hematopoietic Stem Cell Transplantation , Lymphoma, Large B-Cell, Diffuse , Peripheral Blood Stem Cell Transplantation , Humans , Peripheral Blood Stem Cell Transplantation/methods , Cytarabine/adverse effects , Retrospective Studies , Transplantation, Autologous , Hematopoietic Stem Cell Transplantation/adverse effects , Etoposide/adverse effects , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Melphalan/adverse effects , Transplantation Conditioning/methods , Treatment Outcome
3.
J Nippon Med Sch ; 90(1): 126-135, 2023 Mar 11.
Article in English | MEDLINE | ID: mdl-36436914

ABSTRACT

Hemophagocytic lymphohistiocytosis (HLH) involves pathological histiocytes and phagocytosis of normal blood cells through activation of inflammatory cytokines. We report a case of Epstein-Barr virus-HLH in a 75-year-old woman who presented with fever, thrombocytopenia, and loss of consciousness. Epstein-Barr virus-HLH was diagnosed after we identified massive hemophagocytosis in bone marrow and Epstein-Barr virus DNA in cerebrospinal fluid. The HLH-2004 protocol was applied, and lactate dehydrogenase levels-which reflect HLH disease status-decreased. However, persistent loss of consciousness and multiple organ failure led to the patient's death on day 18. Most cases of primary and secondary HLH involve pediatric patients; adult cases are rare. Few cases of central nervous system involvement in older adults have been reported. Therefore, accumulation of more data will help in developing better treatment strategies.


Subject(s)
Epstein-Barr Virus Infections , Lymphohistiocytosis, Hemophagocytic , Female , Humans , Child , Aged , Lymphohistiocytosis, Hemophagocytic/complications , Herpesvirus 4, Human , Epstein-Barr Virus Infections/complications , Central Nervous System , Unconsciousness/complications
4.
Intern Med ; 60(20): 3299-3304, 2021.
Article in English | MEDLINE | ID: mdl-34657908

ABSTRACT

Allogeneic hemopoietic stem cell transplantation (allo-HSCT) is the only curative therapy for refractory hematological malignancies. However, there are many treatment-related complications, including organ disorders, graft-versus-host disease (GVHD), and infectious diseases. Furthermore, there are many unclear points regarding central nervous system (CNS) complications, and the prognosis in patients with CNS complications is extremely poor. We herein report a 49-year-old woman who developed CNS-GVHD after a second transplantation for therapy-related myelodysplastic syndrome. CNS-GVHD in this case was refractory to all treatments, including steroids, and progressed. We also present a review of the literature about the symptoms, diagnosis, and treatment of CNS-GVHD.


Subject(s)
Graft vs Host Disease , Hematopoietic Stem Cell Transplantation , Myelodysplastic Syndromes , Central Nervous System , Female , Graft vs Host Disease/diagnosis , Graft vs Host Disease/etiology , Hematopoietic Stem Cell Transplantation/adverse effects , Humans , Middle Aged , Myelodysplastic Syndromes/therapy
5.
Surg Case Rep ; 7(1): 189, 2021 Aug 21.
Article in English | MEDLINE | ID: mdl-34417909

ABSTRACT

BACKGROUND: Postoperative bleeding in thyroid surgery is a serious complication with fatal outcomes. Risk factors for postoperative hemorrhage have been reported as old age, male sex, Graves' disease, use of anticoagulants, and hematological disorders. Among the hematological diseases, congenital hemophilia is an inherited bleeding disorder characterized by absence or reduced levels of clotting factors VIII or IX. Most patients with hemophilia display bleeding symptoms during infancy or childhood, but diagnosis could be delayed in mild cases. We report a case of congenital hemophilia A that was diagnosed after three episodes of postoperative bleeding after thyroid surgery. CASE PRESENTATION: A 46-year-old man developed repeated postoperative hemorrhage after thyroid surgery for thyroid cancer. In this case, several irregularities were seen in the postoperative course, such as a relatively long interval between surgery and bleeding, the lack of an obvious bleeding point, fresh red blood dripping from the drain insertion site on the second postoperative day, and repeated bleeding three times. We therefore considered that the cause of postoperative hemorrhage might be other than the surgical operations. After a thorough examination, hemophilia A was diagnosed. CONCLUSIONS: Hemophilia is a risk factor for postoperative bleeding in thyroid surgery. However, mild hemophilia shows normal prothrombin time and activated partial thromboplastin time. We encountered a case of papillary thyroid carcinoma associated with congenital hemophilia A, which was diagnosed after repeated bleeding.

6.
J Nippon Med Sch ; 88(1): 45-53, 2021 Mar 11.
Article in English | MEDLINE | ID: mdl-32238739

ABSTRACT

BACKGROUND: Because peripheral blood stem cell (PBSC) collection places a burden on the patient and should ideally be completed in a single procedure, a convenient clinical predictive factor is needed. METHODS: This retrospective study included 72 patients who underwent autologous PBSC collection. A median volume of 3.9 × 106 CD34-positive cells/kg (range: 0.3-47.4 × 106 cells/kg) was collected on the first day. We defined failure as inability to collect 2.0 × 106 cells/kg on the first day. PBSC collection was classified as failed (n = 25, 34.7%) and successful (n = 47, 65.3%), and patient clinical characteristics were analyzed. RESULTS: The success group had significantly more cases in which a differential white blood cell count in peripheral blood on the day of PBSC collection detected promyelocytes (n = 34 [72.3%] vs. n = 11 [44.0%] in the failure group; P = 0.008). Sixty-two patients underwent autologous PBSC transplantation (median number of transplanted cells, 5.6 × 106/µL; range: 1.60-47.4 × 106 cells/µL). Among transplanted patients, the success and failure groups did not significantly differ in relation to the interval until neutrophil, platelet, or red blood cell engraftment. CONCLUSION: The presence of promyelocytes in peripheral blood may be a useful indicator of the optimal timing for single-step PBSC collection.


Subject(s)
Granulocyte Precursor Cells , Peripheral Blood Stem Cell Transplantation/methods , Peripheral Blood Stem Cells , Tissue and Organ Harvesting/methods , Transplantation, Autologous/methods , Adolescent , Adult , Aged , Antigens, CD34 , Female , Humans , Leukemia, Promyelocytic, Acute/therapy , Leukocyte Count , Lymphoma/therapy , Male , Middle Aged , Multiple Myeloma/therapy , Retrospective Studies , Time Factors , Young Adult
7.
J Nippon Med Sch ; 87(3): 142-152, 2020 Jul 13.
Article in English | MEDLINE | ID: mdl-32009070

ABSTRACT

BACKGROUND: Because the cause of liver dysfunction after allogeneic hematopoietic stem cell transplantation (HSCT) is difficult to identify in the early stages, treatment may be delayed. Therefore, early factors associated with unfavorable outcomes of liver dysfunction must be identified. The objective of this study was to identify unfavorable prognostic factors for liver dysfunction during the early period after transplantation. METHODS: We defined liver dysfunction as elevated liver or biliary enzyme levels (corresponding to Grade 2 in the Common Terminology Criteria for Adverse Events version 4.0) within 30 days of transplantation and retrospectively investigated data from 82 patients who had undergone allogeneic HSCT at our center. RESULTS: Elevated liver or biliary enzyme levels were observed in almost half of the patients studied (n=40, 48.7%). Elevated total bilirubin (T-Bil) level was the most frequently observed unfavorable prognostic factor and had the greatest effect on overall survival (OS), progression-free survival (PFS), and non-relapse mortality (NRM) (probability of unfavorable outcome in patients without and with elevated T-Bil level: OS, 58.9% vs. 15.4%, p < 0.001; PFS, 46.4% vs. 15.4%, p < 0.001; NRM, 10.7% vs. 53.8%, p < 0.001). Moreover, the probability of an unfavorable outcome increased in relation to the degree of T-Bil elevation and absence of improvement over time in T-Bil level. CONCLUSION: Elevated T-Bil level was an important marker of outcomes for liver dysfunction after allogeneic HSCT.


Subject(s)
Bilirubin/blood , Hematopoietic Stem Cell Transplantation/adverse effects , Liver Diseases/diagnosis , Liver Diseases/etiology , Adolescent , Adult , Allografts , Biomarkers , Female , Hematopoietic Stem Cell Transplantation/mortality , Humans , Male , Middle Aged , Prognosis , Retrospective Studies , Survival Rate , Time Factors , Young Adult
8.
Acta Haematol ; 143(5): 452-464, 2020.
Article in English | MEDLINE | ID: mdl-31822013

ABSTRACT

BACKGROUND: Acute kidney injury (AKI) and chronic kidney disease (CKD) are considered common complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). OBJECTIVES AND METHOD: In this study, 114 patients who had undergone allo-HSCT were retrospectively analyzed to investigate the risk factors for onset of posttransplant AKI and CKD as defined by the new Kidney Disease Improving Global Outcomes criteria. RESULTS: Seventy-four patients (64.9%) developed AKI and 25 (21.9%) developed CKD. The multivariate analysis showed that the risk factors for developing stage 1 or higher AKI were age ≥46 years at the time of transplant (p = 0.001) and use of ≥3 nephrotoxic drugs (p = 0.036). For CKD, the associated risk factors were disease status other than complete remission at the time of transplantation (p = 0.018) and onset of AKI after transplant (p = 0.035). The 5-year overall survival (OS) was significantly reduced by development of AKI (p < 0.001), but not CKD. Posttransplant AKI significantly increased the 5-year nonrelapse mortality (p < 0.001), whereas posttransplant CKD showed an increasing tendency, but the difference was not significant. CONCLUSIONS: Posttransplant AKI impacts OS, significantly increases the risk of CKD, and is significantly associated with disseminated intravascular coagulation and use of ˃3 nephrotoxic drugs.


Subject(s)
Acute Kidney Injury/etiology , Hematologic Neoplasms/therapy , Hematopoietic Stem Cell Transplantation/adverse effects , Renal Insufficiency, Chronic/etiology , Acute Kidney Injury/pathology , Adolescent , Adult , Child , Female , Hematologic Neoplasms/mortality , Hematologic Neoplasms/pathology , Humans , Male , Middle Aged , Multivariate Analysis , Odds Ratio , Prognosis , Remission Induction , Renal Insufficiency, Chronic/pathology , Retrospective Studies , Risk Factors , Survival Rate , Transplantation, Homologous , Young Adult
9.
Rinsho Ketsueki ; 60(8): 929-931, 2019.
Article in Japanese | MEDLINE | ID: mdl-31484892

ABSTRACT

A 51-year-old man was diagnosed with stage IV mantle cell lymphoma based on terminal ileum biopsy and treated with the R-CHOP regimen. Abdominal CT to assess continuous fever after three courses of R-CHOP revealed three low-density areas in the liver. PCR of the fluid obtained by percutaneous drainage revealed Entamoeba histolytica positivity, although the cultures were negative. Metronidazole treatment achieved cure. The patient was not a homosexual but had an 8-month stay in Lesotho 21 years ago, leading to the possibility that E. histolytica infection at the time continued as an asymptomatic colonization until the initiation of corticosteroid-containing chemotherapy.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/adverse effects , Entamoeba histolytica , Liver Abscess, Amebic , Lymphoma, Mantle-Cell , Antibodies, Monoclonal, Murine-Derived/adverse effects , Cyclophosphamide/adverse effects , Doxorubicin/adverse effects , Humans , Liver Abscess, Amebic/chemically induced , Lymphoma, Mantle-Cell/drug therapy , Male , Middle Aged , Prednisone/adverse effects , Rituximab , Vincristine/adverse effects
10.
Int J Lab Hematol ; 41(4): 461-471, 2019 Aug.
Article in English | MEDLINE | ID: mdl-30970181

ABSTRACT

INTRODUCTION: Acute myelogenous leukemia (AML) in elderly patients is associated with an increased incidence of complications and treatment-related toxicity because of the frequency of comorbid disease and age-related deterioration in organ function. Despite advances in AML treatment in recent years, elderly patients have experienced limited benefit, and their outcomes remain poor. This study aimed to perform a comprehensive gene mutation analysis in elderly AML patients and identify gene mutations that could serve as prognostic factors. METHODS: An analysis of gene mutations was performed for 281 AML patients, including 98 elderly patients aged 65 years or above. RESULTS: Compared to younger AML patients, elderly patients showed a higher frequency of the following gene mutations: TP53 (P = 0.026), PTPN11 (P = 0.006), RUNX1 (P = 0.024), TET2 (P = 0.002), and ASXL1 (P = 0.023). The complete remission rate was significantly lower in DNMT3A mutation-positive cases (4.26%, P = 0.011) and TP53 mutation-positive cases (2.13%, P = 0.031) than in negative cases. The overall survival rate was significantly poorer in cases with FLT3-ITD (P = 0.003), DNMT3A (P = 0.033), or TP53 mutation (P < 0.001). Conversely, cases with PTPN11 mutation (P = 0.014) had a significantly more favorable prognosis. In multivariate analysis, FLT3-ITD (P = 0.011) and TP53 mutation positivity (P = 0.002) were independent poor prognostic factors, as were a performance status of 3 or above (P < 0.001) and poor cytogenetic prognosis (P = 0.001). In contrast, PTPN11 mutation positivity (P = 0.023) was an independent favorable prognosis factor. CONCLUSION: Analysis of gene mutations in elderly AML patients is very important, not only for establishing prognosis, but also for introducing appropriate molecular-targeted treatments.


Subject(s)
Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/mortality , Mutation , Neoplasm Proteins/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Disease-Free Survival , Female , Humans , Male , Middle Aged , Remission Induction , Survival Rate
11.
Intern Med ; 55(12): 1537-45, 2016.
Article in English | MEDLINE | ID: mdl-27301502

ABSTRACT

Objective In hematological malignancy patients, the complication of acute respiratory failure often reaches a degree of severity that necessitates mechanical ventilation. The objective of the present study was to investigate the therapeutic outcomes of mechanical ventilation in hematological malignancy patients with respiratory failure and to analyze the factors that are associated with successful treatment in order to identify the issues that should be addressed in the future. Methods The present study was a retrospective analysis of 71 hematological malignancy patients with non-cardiogenic acute respiratory failure who were treated with mechanical ventilation at Nippon Medical School Hospital between 2003 and 2014. Results Twenty-six patients (36.6%) were treated with mechanical ventilation in an intensive care unit (ICU). Non-invasive positive pressure ventilation (NPPV) was applied in 29 cases (40.8%). The rate of successful mechanical ventilation treatment with NPPV alone was 13.8%. The rate of endotracheal extubation was 17.7%. A univariate analysis revealed that the following factors were associated with the successful extubation of patients who received invasive mechanical ventilation: respiratory management in an ICU (p=0.012); remission of the hematological disease (p=0.011); female gender (p=0.048); low levels of accompanying non-respiratory organ failure (p=0.041); and the non-use of extracorporeal circulation (p=0.005). A subsequent multivariate analysis revealed that respiratory management in an ICU was the only variable associated with successful extubation (p=0.030). Conclusion The outcomes of hematological malignancy patients who receive mechanical ventilation treatment for respiratory failure are very poor. Respiratory management in an ICU environment may be useful in improving the therapeutic outcomes of such patients.


Subject(s)
Hematologic Neoplasms/complications , Respiration, Artificial/methods , Respiratory Insufficiency/etiology , Respiratory Insufficiency/therapy , Acute Disease , Adult , Aged , Female , Humans , Intensive Care Units , Male , Middle Aged , Positive-Pressure Respiration/methods , Retrospective Studies , Treatment Outcome
12.
Intern Med ; 48(10): 775-81, 2009.
Article in English | MEDLINE | ID: mdl-19443971

ABSTRACT

BACKGROUND/AIMS: Secondary hemophagocytic syndrome (hemophagocytic lymphohistiocytosis, HLH) follows viral infection, malignant disorders, and autoimmune disease. Criteria for HLH diagnosis, which were proposed in 2004, include hypertriglyceridemia. However, some studies reported the absence of hypertriglyceridemia in patients with secondary HLH, differing from those with primary HLH. SUBJECTS AND METHODS: In this study, we investigated the presence or absence of hypertriglyceridemia in 28 patients who were diagnosed with secondary HLH between 1997 and 2007 retrospectively. There were no patients undergoing treatment for those with a history of hyperlipidemia. RESULTS: The subjects consisted of 14 patients with lymphoma-associated HLH, 11 with virus-associated HLH, 2 with autoimmune disease-associated HLH, and 1 with post transplantation HLH. In 19 patients (68%), hypertriglyceridemia was noted on diagnosis or during the disease period (mean: 242 mg/dL). Furthermore, the triglyceride (TG) level decreased with the treatment-related amelioration of HLH (mean level before and after treatment: 297 and 136 mg/dL, respectively, p=0.0001). CONCLUSION: These results suggest that the TG level is useful for diagnosing HLH and evaluating the treatment response. TG measurement is simple and inexpensive; therefore, this parameter can be determined several times to evaluate the treatment response.


Subject(s)
Lymphohistiocytosis, Hemophagocytic/blood , Lymphohistiocytosis, Hemophagocytic/diagnosis , Triglycerides/blood , Adolescent , Adult , Aged , Aged, 80 and over , Autoimmune Diseases/complications , Female , Hematopoietic Stem Cell Transplantation/adverse effects , Humans , Hypertriglyceridemia/blood , Hypertriglyceridemia/complications , Lymphohistiocytosis, Hemophagocytic/drug therapy , Lymphohistiocytosis, Hemophagocytic/etiology , Lymphoma/complications , Male , Middle Aged , Retrospective Studies , Treatment Outcome , Virus Diseases/complications , Young Adult
13.
Int J Hematol ; 85(2): 97-100, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17321984

ABSTRACT

Pure white cell aplasia (PWCA) is a rare hematologic disorder characterized by agranulocytosis, a lack of virtually all neutrophil-lineage cells (from neutrophils to myeloblasts) in the bone marrow, and normal erythropoiesis and megakaryocy-topoiesis. We report the first case of PWCA that developed in a patient with primary biliary cirrhosis (PBC). An 83-year-old woman, who had had an elevated serum alkaline phosphatase level and shown positivity for serum antimitochondrial antibodies for 10 years, was referred to us because of a perianal abscess. She had severe neutropenia, and her bone marrow showed typical findings of PWCA. Although methylprednisolone pulse therapy induced complete neutrophil recovery, this effect was transient. She died of infection, and the autopsy confirmed the diagnosis of PBC. In vitro investigations showed that factors inhibitory to normal CD34 cell-derived granulopoiesis were present in the patient's serum.


Subject(s)
Agranulocytosis/etiology , Liver Cirrhosis, Biliary/complications , Aged, 80 and over , Agranulocytosis/blood , Agranulocytosis/drug therapy , Agranulocytosis/pathology , Anti-Inflammatory Agents/administration & dosage , Bone Marrow/pathology , Erythropoiesis/drug effects , Fatal Outcome , Female , Humans , Infections/blood , Infections/etiology , Infections/pathology , Leukopoiesis/drug effects , Liver Cirrhosis, Biliary/blood , Liver Cirrhosis, Biliary/drug therapy , Liver Cirrhosis, Biliary/pathology , Methylprednisolone/administration & dosage
14.
Nature ; 428(6984): 767-71, 2004 Apr 15.
Article in English | MEDLINE | ID: mdl-15085137

ABSTRACT

During mitosis, the mitotic spindle, a bipolar structure composed of microtubules (MTs) and associated motor proteins, segregates sister chromatids to daughter cells. Initially some MTs emanating from one centrosome attach to the kinetochore at the centromere of one of the duplicated chromosomes. This attachment allows rapid poleward movement of the bound chromosome. Subsequent attachment of the sister kinetochore to MTs growing from the other centrosome results in the bi-orientation of the chromosome, in which interactions between kinetochores and the plus ends of MTs are formed and stabilized. These processes ensure alignment of chromosomes during metaphase and their correct segregation during anaphase. Although many proteins constituting the kinetochore have been identified and extensively studied, the signalling responsible for MT capture and stabilization is unclear. Small GTPases of the Rho family regulate cell morphogenesis by organizing the actin cytoskeleton and regulating MT alignment and stabilization. We now show that one member of this family, Cdc42, and its effector, mDia3, regulate MT attachment to kinetochores.


Subject(s)
Carrier Proteins/metabolism , Kinetochores/metabolism , Microtubules/metabolism , cdc42 GTP-Binding Protein/metabolism , Animals , Carrier Proteins/genetics , Formins , Guanosine 5'-O-(3-Thiotriphosphate)/metabolism , Guanosine Diphosphate/metabolism , HeLa Cells , Humans , Mice , Mitosis/drug effects , Mutation , NIH 3T3 Cells , Signal Transduction/drug effects , Spindle Apparatus/metabolism , rho GTP-Binding Proteins/genetics , rho GTP-Binding Proteins/metabolism
15.
J Cell Biol ; 157(5): 819-30, 2002 May 27.
Article in English | MEDLINE | ID: mdl-12021256

ABSTRACT

The small GTPase Rho acts on two effectors, ROCK and mDia1, and induces stress fibers and focal adhesions. However, how ROCK and mDia1 individually regulate signals and dynamics of these structures remains unknown. We stimulated serum-starved Swiss 3T3 fibroblasts with LPA and compared the effects of C3 exoenzyme, a Rho inhibitor, with those of Y-27632, a ROCK inhibitor. Y-27632 treatment suppressed LPA-induced formation of stress fibers and focal adhesions as did C3 exoenzyme but induced membrane ruffles and focal complexes, which were absent in the C3 exoenzyme-treated cells. This phenotype was suppressed by expression of N17Rac. Consistently, the amount of GTP-Rac increased significantly by Y-27632 in LPA-stimulated cells. Biochemically, Y-27632 suppressed tyrosine phosphorylation of paxillin and focal adhesion kinase and not that of Cas. Inhibition of Cas phosphorylation with PP1 or expression of a dominant negative Cas mutant inhibited Y-27632-induced membrane ruffle formation. Moreover, Crk-II mutants lacking in binding to either phosphorylated Cas or DOCK180 suppressed the Y-27632-induced membrane ruffle formation. Finally, expression of a dominant negative mDia1 mutant also inhibited the membrane ruffle formation by Y-27632. Thus, these results have revealed the Rho-dependent Rac activation signaling that is mediated by mDia1 through Cas phosphorylation and antagonized by the action of ROCK.


Subject(s)
Botulinum Toxins , Carrier Proteins/metabolism , Protein Serine-Threonine Kinases/metabolism , Proteins , Proto-Oncogene Proteins , rac GTP-Binding Proteins/metabolism , rho GTP-Binding Proteins/metabolism , 3T3 Cells , ADP Ribose Transferases/pharmacology , Actin Cytoskeleton/drug effects , Actin Cytoskeleton/metabolism , Amides/pharmacology , Animals , Carrier Proteins/genetics , Crk-Associated Substrate Protein , Enzyme Inhibitors/pharmacology , Focal Adhesions/drug effects , Focal Adhesions/metabolism , Formins , Gene Expression/physiology , HeLa Cells , Humans , Intracellular Signaling Peptides and Proteins , Lysophospholipids/pharmacology , Mice , Mutation/physiology , Phosphoproteins/metabolism , Phosphorylation , Protein Kinases/genetics , Proto-Oncogene Proteins c-crk , Pyridines/pharmacology , Retinoblastoma-Like Protein p130 , Signal Transduction/physiology , Tyrosine/metabolism , rho-Associated Kinases
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