Biomedical subjects

Ichiro Ota

Publications and source records attributed to Ichiro Ota.

13 recordsLinked to original sources

PubMed2006

A Wnt-Axin2-GSK3beta cascade regulates Snail1 activity in breast cancer cells.

Accumulating evidence indicates that hyperactive Wnt signalling occurs in association with the development and progression of human breast cancer. As a consequence of engaging the canonical Wnt pathway, a beta-catenin-T-cell factor (TCF) transcriptional complex is generated, which has been postulated to trigger the epithelial-mesenchymal transition (EMT) that characterizes the tissue-invasive phenotype. However, the molecular mechanisms by which the beta-catenin-TCF complex induces EMT-like programmes remain undefined. Here, we demonstrate that canonical Wnt signalling engages tumour cell dedifferentiation and tissue-invasive activity through an Axin2-dependent pathway that stabilizes the Snail1 zinc-transcription factor, a key regulator of normal and neoplastic EMT programmes. Axin2 regulates EMT by acting as a nucleocytoplasmic chaperone for GSK3beta, the dominant kinase responsible for controlling Snail1 protein turnover and activity. As dysregulated Wnt signalling marks a diverse array of cancerous tissue types, the identification of a beta-catenin-TCF-regulated Axin2-GSK3beta-Snail1 axis provides new mechanistic insights into cancer-associated EMT programmes.

Amino Acid Sequence↗

PubMed2005

MT1-matrix metalloproteinase directs arterial wall invasion and neointima formation by vascular smooth muscle cells.

During pathologic vessel remodeling, vascular smooth muscle cells (VSMCs) embedded within the collagen-rich matrix of the artery wall mobilize uncharacterized proteolytic systems to infiltrate the subendothelial space and generate neointimal lesions. Although the VSMC-derived serine proteinases, plasminogen activator and plasminogen, the cysteine proteinases, cathepsins L, S, and K, and the matrix metalloproteinases MMP-2 and MMP-9 have each been linked to pathologic matrix-remodeling states in vitro and in vivo, the role that these or other proteinases play in allowing VSMCs to negotiate the three-dimensional (3-D) cross-linked extracellular matrix of the arterial wall remains undefined. Herein, we demonstrate that VSMCs proteolytically remodel and invade collagenous barriers independently of plasmin, cathepsins L, S, or K, MMP-2, or MMP-9. Instead, we identify the membrane-anchored matrix metalloproteinase, MT1-MMP, as the key pericellular collagenolysin that controls the ability of VSMCs to degrade and infiltrate 3-D barriers of interstitial collagen, including the arterial wall. Furthermore, genetic deletion of the proteinase affords mice with a protected status against neointimal hyperplasia and lumen narrowing in vivo. These studies suggest that therapeutic interventions designed to target MT1-MMP could prove beneficial in a range of human vascular disease states associated with the destructive remodeling of the vessel wall extracellular matrix.

Animals↗

PubMed2005

Wnt-dependent regulation of the E-cadherin repressor snail.

Down-regulation of E-cadherin marks the initiation of the epithelial-mesenchymal transition, a process exploited by invasive cancer cells. The zinc finger transcription factor, Snail, functions as a potent repressor of E-cadherin expression that can, acting alone or in concert with the Wnt/beta-catenin/T cell factor axis, induce an epithelial-mesenchymal transition. Although mechanisms that coordinate signaling events initiated by Snail and Wnt remain undefined, we demonstrate that Snail displays beta-catenin-like canonical motifs that support its GSK3beta-dependent phosphorylation, beta-TrCP-directed ubiquitination, and proteasomal degradation. Accordingly, Wnt signaling inhibits Snail phosphorylation and consequently increases Snail protein levels and activity while driving an in vivo epithelial-mesenchymal transition that is suppressed following Snail knockdown. These findings define a potential mechanism whereby Wnt signaling stabilizes Snail and beta-catenin proteins in tandem fashion so as to cooperatively engage transcriptional programs that control an epithelial-mesenchymal transition.

Amino Acid Sequence↗

PubMed2004

Tumor cell traffic through the extracellular matrix is controlled by the membrane-anchored collagenase MT1-MMP.

As cancer cells traverse collagen-rich extracellular matrix (ECM) barriers and intravasate, they adopt a fibroblast-like phenotype and engage undefined proteolytic cascades that mediate invasive activity. Herein, we find that fibroblasts and cancer cells express an indistinguishable pericellular collagenolytic activity that allows them to traverse the ECM. Using fibroblasts isolated from gene-targeted mice, a matrix metalloproteinase (MMP)-dependent activity is identified that drives invasion independently of plasminogen, the gelatinase A/TIMP-2 axis, gelatinase B, collagenase-3, collagenase-2, or stromelysin-1. In contrast, deleting or suppressing expression of the membrane-tethered MMP, MT1-MMP, in fibroblasts or tumor cells results in a loss of collagenolytic and invasive activity in vitro or in vivo. Thus, MT1-MMP serves as the major cell-associated proteinase necessary to confer normal or neoplastic cells with invasive activity.

Animals↗

PubMed2004

MT1-MMP-dependent neovessel formation within the confines of the three-dimensional extracellular matrix.

During angiogenesis, endothelial cells initiate a tissue-invasive program within an interstitial matrix comprised largely of type I collagen. Extracellular matrix-degradative enzymes, including the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, are thought to play key roles in angiogenesis by binding to docking sites on the cell surface after activation by plasmin- and/or membrane-type (MT) 1-MMP-dependent processes. To identify proteinases critical to neovessel formation, an ex vivo model of angiogenesis has been established wherein tissue explants from gene-targeted mice are embedded within a three-dimensional, type I collagen matrix. Unexpectedly, neither MMP-2, MMP-9, their cognate cell-surface receptors (i.e., beta3 integrin and CD44), nor plasminogen are essential for collagenolytic activity, endothelial cell invasion, or neovessel formation. Instead, the membrane-anchored MMP, MT1-MMP, confers endothelial cells with the ability to express invasive and tubulogenic activity in a collagen-rich milieu, in vitro or in vivo, where it plays an indispensable role in driving neovessel formation.

Animals↗

PubMed2004

Clinical comparison of Healon5 and Healon in phacoemulsification and intraocular lens implantation; Randomized multicenter study.

PURPOSE: To compare the overall clinical performance during phacoemulsification and intraocular lens (IOL) implantation, the effect on intraocular pressure (IOP), and the effect on corneal endothelium of Healon5 (sodium hyaluronate 2.3%) and Healon (sodium hyaluronate 1.0%) ophthalmic viscosurgical devices (OVDs). SETTING: Multicenter study. METHODS: In this randomized prospective clinical study, the performance of Healon5 (viscoadaptive; dispersive and cohesive) and Healon (cohesive) during cataract surgery was evaluated in 157 patients, 79 with Healon5 and 78 with Healon. Surgeons evaluated the following on a 5-point scale: retention during phacoemulsification (primary endpoint), ease of injection, anterior chamber maintenance during continuous curvilinear capsulorhexis (CCC), facilitation of IOL implantation, and ease of removal from the eye. Masked examiners other than the surgeon performed the following measurements: IOP preoperatively and 5 and 24 hours, 7 days, and 3 months postoperatively; corneal thickness before and 24 hours, 7 days, and 3 months postoperatively; and corneal endothelial cell count preoperatively and 3 months postoperatively. RESULTS: Intraocular retention during phacoemulsification was assessed as good or very good in 77% in the Healon5 group and 8% in the Healon group; the difference was statistically significant (P<.0001, Wilcoxon rank sum test). The Healon5 group had significantly better scores for anterior chamber maintenance during CCC (P<.0001) and facilitation of IOL implantation (P =.032), and the Healon group had significantly better scores for ease of injection (P<.0001) and ease of removal (P<.0001). There were no statistically significant between-group differences in IOP, corneal endothelial cell count, or corneal thickness. CONCLUSIONS: Surgeons rated Healon5 better than Healon in retention during phacoemulsification, anterior chamber maintenance during CCC, and facilitation of IOL implantation. They assessed Healon as easier to inject and remove. There was no difference in safety-related parameters between the 2 OVDs. These findings indicate that Healon5 is effective in cataract surgery.

Aged↗

PubMed2004

Increased expression of integrin alpha3beta1 in highly brain metastatic subclone of a human non-small cell lung cancer cell line.

To clarify the roles of integrin and extracellular matrix (ECM) in the process of non-small cell lung cancer (NSCLC) brain metastasis, we established an in vivo model of brain metastasis of human NSCLC cell line EBC-1/original in athymic mice, and established highly brain metastatic subclone EBC-1/brain and highly bone metastatic subclone EBC-1/bone. Integrin expression of these subclones was evaluated by flow cytometry. In vitro cell attachment, migration and proliferation assays with ECMs were performed using these subclones. Expression of integrin alpha3 subunit was higher in EBC-1/brain than in both EBC-1/original and EBC-1/bone. In vitro cell attachment, migration, and proliferation assays revealed that EBC-1/brain had higher affinity and higher reactivity to laminin than EBC-1/original and EBC-1/bone. Blocking of integrin alpha3beta1 significantly (P < 0.05) decreased brain metastasis by EBC-1/brain. Interaction of integrin alpha3beta1 and laminin plays important roles in the process of brain metastasis of non-small cell lung cancer.

Animals↗

PubMed2004

Glycerol enhances CDDP-induced growth inhibition of thyroid anaplastic carcinoma tumor carrying mutated p53 gene.

To increase the chemo-sensitivity of anaplastic thyroid carcinoma, we examined the effects of glycerol on the tumor growth after CDDP treatment. The cultured cells of an anaplastic thyroid carcinoma cell line (8305c) carrying a mutated p53 gene (mp53) were transplanted into the thighs of nude mice. Tumor growth was evaluated until 24 days after intraperitoneal injection of CDDP and/or pre-injection of glycerol to the tumor. We treated the mice with half the tumor volume of glycerol (1.2 M) and/or CDDP at 6 mg/kg (BW) either of which hardly inhibited tumor growth by itself. When we treated the mice with the combination of glycerol and CDDP at these concentrations, however, a clear delay of the tumor growth was observed. We also immunohistochemically analyzed the effects of glycerol on the induction of caspase-3 activity and apoptosis. Cells positive for cleavage to active caspase-3 and 85 kDa PARP, and apoptosis were hardly observed in the tumors when they were treated with glycerol or CDDP alone. In contrast, when they were treated with CDDP combined with glycerol, such positive cells were significantly increased. It has been shown that glycerol synergistically enhanced the effects of CDDP as a tumor suppressive agent through the induction of caspase-3-mediated apoptosis in 8305c tumors. Therefore, glycerol might be useful for chemotherapy in patients with mp53 cancer cells.

Animals↗

PubMed2003

EZH2 is a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells.

The Polycomb Group Protein EZH2 is a transcriptional repressor involved in controlling cellular memory and has been linked to aggressive prostate cancer. Here we investigate the functional role of EZH2 in cancer cell invasion and breast cancer progression. EZH2 transcript and protein were consistently elevated in invasive breast carcinoma compared with normal breast epithelia. Tissue microarray analysis, which included 917 samples from 280 patients, demonstrated that EZH2 protein levels were strongly associated with breast cancer aggressiveness. Overexpression of EZH2 in immortalized human mammary epithelial cell lines promotes anchorage-independent growth and cell invasion. EZH2-mediated cell invasion required an intact SET domain and histone deacetylase activity. This study provides compelling evidence for a functional link between dysregulated cellular memory, transcriptional repression, and neoplastic transformation.

Breast↗

PubMed2003

Localized liquefied after-cataract.

We report 2 cases with a new type of after-cataract. In both, a milky white substance accumulated in a semicircular, closed chamber formed by the intraocular lens optic and the posterior lens capsule. Unlike in previous reports, the closed chamber did not cover the entire capsule but was based on residual lens remnants in the equatorial region of the lens capsule.

Aged↗

PubMed2003

ESCRS Binkhorst lecture 2002: Pseudophakic preservative maculopathy.

Many antiglaucoma eyedrops are reported to cause cystoid macular edema (CME) in aphakia and pseudophakia. We review 4 clinical and laboratory studies that compare the incidence of CME in early postoperative pseudophakia in eyes that received preserved latanoprost and timolol, nonpreserved timolol, and the preserved and nonpreserved vehicle for these drugs and looked at the morphological damage to cells and the changes in the indicators of cytokine and prostaglandin (PG) synthesis caused by latanoprost and timolol and the preservative benzalkonium chloride. Based on the findings of these studies, which indicate that the preservative causes increased synthesis of PGs and other substances and intensified postoperative inflammation, the term pseudophakic preservative maculopathy is proposed for CME caused by antiglaucoma eyedrops.

Aqueous Humor↗

PubMed2002

Glycerol as a chemical chaperone enhances radiation-induced apoptosis in anaplastic thyroid carcinoma cells.

INTRODUCTION: Anaplastic thyroid carcinoma, which is one of the most aggressive, malignant tumors in humans, results in an extremely poor prognosis despite chemotherapy and radiotherapy. The present study was designed to evaluate therapeutic effects of radiation by glycerol on p53-mutant anaplastic thyroid carcinoma cells (8305c cells). To examine the effectiveness of glycerol in radiation induced lethality for anaplastic thyroid carcinoma 8305c cells, we performed colony formation assay and apoptosis analysis. RESULTS: Apoptosis was analyzed with Hoechst 33342 staining and DNA ladder formation assay. 8305c cells became radiosensitive when glycerol was added to culture medium before X-ray irradiation. Apoptosis was induced by X-rays in the presence of glycerol. However, there was little apoptosis induced by X-ray irradiation or glycerol alone. The binding activity of whole cell extracts to bax promoter region was induced by X-rays in the presence of glycerol but not by X-rays alone. CONCLUSION: These findings suggest that glycerol is effective against radiotherapy of p53-mutant thyroid carcinomas.

Apoptosis↗

PubMedDate not supplied

Radiation-induced growth inhibition in transplanted human tongue carcinomas with different p53 gene status.

BACKGROUND AND PURPOSE: To test p53-dependency in radiation cancer therapy with X-rays (low-linear energy transfer (LET)) or carbon-ion (C-) beams (high-LET heavy ion), we analyzed the radiation-induced growth rate and apoptosis induction in human tongue carcinomas transplanted into nude mice. MATERIALS AND METHODS: The SAS cells transfected with mutant p53 gene (SAS/mp53) or a neo control gene (SAS/neo) were transplanted into the thigh of each nude mouse. By measuring the tumor weight (TW), tumor regrowth delay was evaluated when the relative tumor weight (RW) reached 5-fold that of the control group. Apoptosis was analyzed by immunohistochemical and ApopTag stainings. RESULTS: SAS/mp53 tumors were more resistant to X-ray irradiation than SAS/neo tumors, but not to C-beam irradiation. The relative biological effectiveness (RBE) of C-beams compared to X-rays was 2.1 in SAS/neo tumors and 2.6 in SAS/mp53 tumors. Apoptotic cells were more frequently observed in SAS/neo tumors than in SAS/mp53 tumors in X-ray irradiation but not in C-beam irradiation. CONCLUSION: The radiation-induced growth inhibition of transplanted SAS cells is suggested to be p53-dependent in X-ray irradiation but not in C-beam irradiation. C-beams are proposed as being useful for cancer radiation therapy regardless of p53 gene status.

Animals↗