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1.
Medicine (Baltimore) ; 101(2): e28433, 2022 Jan 14.
Article in English | MEDLINE | ID: mdl-35029184

ABSTRACT

RATIONALE: Small cell carcinoma (SCC) is a rare subtype of breast cancer and presents a complex diagnostic and treatment challenge, due to paucity of data. To the best of our knowledge, most cases of breast SCC reported in the literature describe a de novo breast primary. Our case is unique as it describes the evolution of an invasive ductal carcinoma after treatment into a SCC of the breast. PATIENT CONCERNS AND DIAGNOSIS: We report a case of a 53-year-old female, lifelong non-smoker, who initially presented with breast mass noted on self examination. Breast and axillary lymph node biopsy demonstrated a hormone receptor positive invasive ductal carcinoma with a metastatic T3 lesion. INTERVENTION: She was treated with first-line palbociclib/letrozole with initial clinical response, and at progression was switched to capecitabine with no response. Repeat biopsy of the axillary lesion showed evolution of the tumor into a triple negative breast cancer. She was then treated with third-line paclitaxel and radiation therapy with good initial response. She eventually had further disease progression and presented with a new mediastinal lymphadenopathy causing SVC syndrome. Biopsy of this showed a small cell variant of breast neuroendocrine carcinoma. Due to the evolution of histology in this case, a retrospective review of her initial breast specimen as well as the second biopsy from the axilla was conducted which confirmed that the mediastinal lymphadenopathy was metastatic from the original breast tumor. OUTCOMES AND LESSONS: We speculate that the initial treatment allowed a minority of treatment-resistant neuroendocrine cells to grow and become the dominant face of the tumor. Our patient had an excellent response to carboplatin/etoposide and consolidative locoregional radiotherapy but presented with an early intracranial recurrence. This is a similar pattern of metastases as seen in lung SCC and highlights a potential role for prophylactic cranial irradiation in breast SCC. Further studies are needed to better understand the biology and treatment of breast SCC which continues to present a challenge for clinicians.


Subject(s)
Breast Neoplasms , Carcinoma, Ductal, Breast , Carcinoma, Small Cell , Lymphadenopathy , Breast Neoplasms/diagnosis , Breast Neoplasms/therapy , Carcinoma, Ductal, Breast/diagnosis , Carcinoma, Ductal, Breast/therapy , Carcinoma, Small Cell/diagnosis , Carcinoma, Small Cell/therapy , Female , Humans , Middle Aged , Retrospective Studies
2.
Diagn Cytopathol ; 49(1): 105-108, 2021 Jan.
Article in English | MEDLINE | ID: mdl-32870607

ABSTRACT

BACKGROUND: Rapid on-site evaluation (ROSE) is a valuable tool for specimen adequacy assessment in thyroid ultrasound (US)-guided fine-needle aspiration (US-guided FNA). To reduce the risk of nondiagnostic samples, additional needle passes may be needed at ROSE to ensure adequate sampling. Recommendations regarding the number of aspirates to ensure specimen adequacy are not well defined. Furthermore, there are limited data regarding nodule characteristics that may require increased sampling. In this study, we investigate conditions associated with requiring more than three needle passes during ROSE. METHODS: A retrospective quality review of all patients who underwent US-guided thyroid FNA by a single board-certified radiologist over a 1-year period was performed. A total of 122 patients were identified: 70 with three passes performed and 52 with more than three passes to achieve adequacy. RESULT: Our data demonstrate that large nodules (≥3 cm) were more likely than small nodules (≤1.1 cm) to require more than three passes to achieve adequacy. If a nodule was predominantly cystic or mixed cystic and solid, the sample was often adequate with only three passes. In cases of thyroiditis or nodules suspicious or diagnostic of neoplasia, there is a trend to require only three passes for adequacy. CONCLUSION: On the basis of the data presented in this study, cytopathologists should be prepared for the potential need to obtain additional needle passes in larger (≥3 cm) nodules and provide reassurance to patients that this is an anticipated finding for these larger nodules.


Subject(s)
Thyroid Gland/pathology , Thyroid Neoplasms/pathology , Thyroid Nodule/pathology , Biopsy, Fine-Needle/methods , Humans , Image-Guided Biopsy/methods , Needles , Retrospective Studies , Specimen Handling/methods , Ultrasonography/methods , Ultrasonography, Interventional/methods
3.
Adv Skin Wound Care ; 31(1): 582-595, 2018 Jan.
Article in English | MEDLINE | ID: mdl-29240586

ABSTRACT

GENERAL PURPOSE: To provide information about the clinical presentation of hypertrophic scars and keloids based on their varied structural components. TARGET AUDIENCE: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES: After completing this continuing education activity, you should be able to: ABSTRACT: Hypertrophic scars and keloids are firm, raised, erythematous plaques or nodules that manifest when the cicatrix fails to properly heal. They result from pathologic wound healing and often cause pain and decreased quality of life. The appearance of such cosmetically unappealing scars affects the confidence and self-esteem of many patients. These scars can also cause dysfunction by interfering with flexion and extension across joints. Both possess some unique and distinct histochemical and physiologic characteristics that set them apart morphologically and at the molecular level. While these entities have been the focus of research for many years, differentiating between them remains challenging for clinicians.This article reviews the clinical presentation of aberrant scars and illustrates how they can be differentiated. It outlines their pathophysiology and emphasizes the unique molecular mechanisms underlying each disorder. It also examines how altered expression levels and the distribution of several factors may contribute to their unique clinical characteristics and presentation. Further research is needed to elucidate optimal treatments and preventive measures for these types of aberrant scarring.


Subject(s)
Cicatrix, Hypertrophic/pathology , Cicatrix, Hypertrophic/physiopathology , Keloid/pathology , Keloid/physiopathology , Wounds and Injuries/complications , Biopsy, Needle , Cicatrix, Hypertrophic/etiology , Cicatrix, Hypertrophic/therapy , Collagen/metabolism , Combined Modality Therapy , Diagnosis, Differential , Disease Progression , Education, Medical, Continuing , Elastin/metabolism , Female , Fibrillin-1/metabolism , Humans , Immunohistochemistry , Keloid/etiology , Keloid/therapy , Male , Prognosis , Risk Assessment , Severity of Illness Index , Wound Healing , Wounds and Injuries/diagnosis
4.
Pediatr Rheumatol Online J ; 13(1): 39, 2015 Oct 06.
Article in English | MEDLINE | ID: mdl-26438123

ABSTRACT

Linear atrophoderma of Moulin (LAM) is an acquired skin condition that manifests in early childhood and adolescence. It likely represents a form of cutaneous mosaicism that presents with linear, hyperpigmented and atrophic lesions appearing on the trunk and limbs. Its clinical appearance varies and may closely resemble that of atrophoderma of Pasini and Pierini (APP) and linear scleroderma. LAM usually follows a benign course and no effective treatment options exist. We present a case of a young and healthy patient that developed such lesions on her upper and lower extremities over 5 years. The initial clinical impression of linear scleroderma was reviewed in favor of LAM following histological examination of the lesions which revealed no significant inflammatory changes. LAM remains a rare and possibly under recognized entity with reports confined only to the dermatologic literature. This case highlights the importance of recognizing LAM and distinguishing it from linear scleroderma given the significant differences in management and prognosis.


Subject(s)
Hyperpigmentation/diagnosis , Skin/pathology , Adolescent , Atrophy , Child , Diagnosis, Differential , Female , Humans , Scleroderma, Localized/diagnosis
5.
Pathol Res Pract ; 210(10): 668-74, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25041835

ABSTRACT

CD98-mediated ß1 and ß3 integrins activation can induce Fak phosphorylation which eventually promotes cell survival, proliferation, and migration. We evaluated the expression of CD98, integrin ß1, integrin ß3 and Fak in 45 cases of matched colorectal cancer (CRC) and liver metastases as well as 35 cases of CRC without liver metastases. There was a gradual increase of the expression of CD98, integrin ß1, integrin ß3 and Fak as tumor progressed from normal colon to carcinoma to budding tumor cells at the invasive front and to liver metastases. The expression of CD98 and integrin ß1 in CRC with liver metastases was significantly higher than that in CRC without liver metastases. Furthermore, for those liver metastases with desmoplastic growth pattern, expression of CD98, integrin ß1, integrin ß3 and Fak at the metastases center was as strong as that at the metastases periphery. For those liver metastases with pushing or replacement growth patterns, more intense expression of these markers was found at the metastases center than the periphery. Overexpression of CD98, integrin ß1, integrin ß3 and Fak is associated with the progression and liver metastases of CRC. Overexpression of these markers in liver metastases requires direct contact between tumor cells and the stroma.


Subject(s)
Cell Movement/physiology , Colorectal Neoplasms/metabolism , Focal Adhesion Kinase 1/metabolism , Fusion Regulatory Protein-1/metabolism , Integrin beta1/metabolism , Integrin beta3/metabolism , Liver Neoplasms/metabolism , Adult , Aged , Aged, 80 and over , Cell Line, Tumor , Colorectal Neoplasms/pathology , Female , Humans , Liver Neoplasms/secondary , Male , Middle Aged , Signal Transduction/physiology
6.
Arterioscler Thromb Vasc Biol ; 31(10): 2287-96, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21757659

ABSTRACT

OBJECTIVE: The tonicity-responsive transcription factor, nuclear factor of activated T cells 5 (NFAT5/tonicity enhancer binding protein [TonEBP]), has been well characterized in numerous cell types; however, NFAT5 function in vascular smooth muscle cells (SMCs) is unknown. Our main objective was to determine the role of NFAT5 regulation in SMCs. METHODS AND RESULTS: We showed that NFAT5 is regulated by hypertonicity in SMCs and is upregulated in atherosclerosis and neointimal hyperplasia. RNAi knockdown of NFAT5 inhibited basal expression of several SMC differentiation marker genes, including smooth muscle α actin (SMαA). Bioinformatic analysis of SMαA revealed 7 putative NFAT5 binding sites in the first intron, and chromatin immunoprecipitation analysis showed NFAT5 enrichment of intronic DNA. Overexpression of NFAT5 increased SMαA promoter-intron activity, which requires an NFAT5 cis element at +1012, whereas dominant-negative NFAT5 decreased SMαA promoter-intron activity. Because it is unlikely that SMCs experience extreme changes in tonicity, we investigated other stimuli and uncovered 2 novel NFAT5-inducing factors: angiotensin II, a contractile agonist, and platelet-derived growth factor-BB (PDGF-BB), a potent mitogen in vascular injury. Angiotensin II stimulated NFAT5 translocation and activity, and NFAT5 knockdown inhibited an angiotensin II-mediated upregulation of SMαA mRNA. PDGF-BB increased NFAT5 protein, and loss of NFAT5 inhibited PDGF-BB-induced SMC migration. CONCLUSIONS: We have identified NFAT5 as a novel regulator of SMC phenotypic modulation and have uncovered the role of NFAT5 in angiotensin II-induced SMαA expression and PDGF-BB-stimulated SMC migration.


Subject(s)
Atherosclerosis/metabolism , Carotid Artery Injuries/metabolism , Muscle, Smooth, Vascular/metabolism , Myocytes, Smooth Muscle/metabolism , NFATC Transcription Factors/metabolism , Tunica Intima/metabolism , Actins/genetics , Actins/metabolism , Angiotensin II/metabolism , Animals , Apolipoproteins E/deficiency , Apolipoproteins E/genetics , Atherosclerosis/genetics , Atherosclerosis/pathology , Becaplermin , Binding Sites , Carotid Artery Injuries/genetics , Carotid Artery Injuries/pathology , Cell Movement , Cell Proliferation , Cells, Cultured , Chromatin Immunoprecipitation , Coculture Techniques , Computational Biology , Disease Models, Animal , Gene Expression Regulation , Genes, Reporter , Humans , Hyperplasia , Introns , Mice , Mice, Knockout , Muscle, Smooth, Vascular/pathology , Myocytes, Smooth Muscle/pathology , NFATC Transcription Factors/genetics , Phenotype , Platelet-Derived Growth Factor/metabolism , Promoter Regions, Genetic , Protein Transport , Proto-Oncogene Proteins c-sis , RNA Interference , RNA, Messenger/metabolism , Rats , Transcription Factors/metabolism , Transfection , Tunica Intima/pathology
7.
Cell Adh Migr ; 4(4): 485-90, 2010.
Article in English | MEDLINE | ID: mdl-20543583

ABSTRACT

α8ß1 integrin is highly expressed in cells with contractile function, such as mesangial cells of the kidneys and vascular smooth muscle cells (VSMCs). Although it promotes migration of neural crest cells and breast cancer cells, recent studies suggest that α8 integrin has a negative regulatory role in VSMC migration. In this review, the question of why α8ß1 integrin plays a dual role in cell migration is raised and discussed. It seems that cells require optimum contractility and balanced tensile forces for migration. α8ß1 integrin promotes migration of cells that are initially in a less than optimal contractile state (e.g. neural cells) and reduces the migration of cells known as contractile cells. α8ß1 integrin can be called "Tensegrin" as it fits perfectly into the tensegrity model (tensional integrity) and seems to play a prominent role in the integration of the tensile forces.


Subject(s)
Antigens, Differentiation/physiology , Cell Movement , Integrins/physiology , Muscle, Smooth, Vascular/cytology , Animals , Cell Proliferation , Humans , Muscle Contraction , Muscle, Smooth, Vascular/physiology , Stress, Mechanical
8.
J Exp Med ; 206(11): 2397-406, 2009 Oct 26.
Article in English | MEDLINE | ID: mdl-19841087

ABSTRACT

Activation of vascular smooth muscle cells (VSMCs) to migrate and proliferate is essential for the formation of intimal hyperplasia. Hence, selectively targeting activated VSMCs is a potential strategy against vaso-occlusive disorders such as in-stent restenosis, vein-graft stenosis, and transplant vasculopathy. We show that CD98 heavy chain (CD98hc) is markedly up-regulated in neointimal and cultured VSMCs, and that activated but not quiescent VSMCs require CD98hc for survival. CD98hc mediates integrin signaling and localizes amino acid transporters to the plasma membrane. SMC-specific deletion of CD98hc did not affect normal vessel morphology, indicating that CD98hc was not required for the maintenance of resident quiescent VSMCs; however, CD98hc deletion reduced intimal hyperplasia after arterial injury. Ex vivo and in vitro, loss of CD98hc suppressed proliferation and induced apoptosis in VSMCs. Furthermore, reconstitution with CD98hc mutants showed that CD98hc interaction with integrins was necessary for the survival of VSMCs. These studies establish the importance of CD98hc in VSMC proliferation and survival. Furthermore, loss of CD98hc was selectively deleterious to activated VSMCs while sparing resident quiescent VSMCs, suggesting that activated VSMCs are physiologically dependent on CD98hc, and hence, CD98hc is a potential therapeutic target in vaso-occlusive disorders.


Subject(s)
Fusion Regulatory Protein 1, Heavy Chain/metabolism , Muscle, Smooth, Vascular/cytology , Myocytes, Smooth Muscle/cytology , Myocytes, Smooth Muscle/metabolism , Amino Acid Transport Systems/metabolism , Animals , Carotid Arteries/metabolism , Carotid Arteries/pathology , Cell Proliferation , Cell Survival , Cells, Cultured , Gene Deletion , Hyperplasia , Integrases/metabolism , Integrins/metabolism , Mice , Microfilament Proteins/metabolism , Muscle Proteins/metabolism , Protein Binding , Tunica Intima/metabolism , Tunica Intima/pathology
9.
Clin Sci (Lond) ; 114(4): 257-64, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18194134

ABSTRACT

Arterial reconstruction procedures, including balloon angioplasty, stenting and coronary artery bypass, are used to restore blood flow in atherosclerotic arteries. Restenosis of these arteries has remained a major limitation of the application of these procedures, especially in the case of balloon angioplasty. Post-angioplasty restenosis results from two major processes: neointimal formation and constrictive remodelling. Neointimal formation is initiated by arterial injury with a resultant loss of contractile phenotype in tunica media, leading to VSMC [vascular SM (smooth muscle) cell] migration from the tunica media to the intima. Migrated VSMCs contribute to the intimal thickening by the excessive synthesis of ECM (extracellular matrix) and proliferation. However, increased neointimal mass is not solely responsible for luminal narrowing. Inward constrictive remodelling is also considered as a major cause of delayed failure of angioplasty. At later stages after angioplasty, the increase in contractile forces leads to lumen narrowing. Recent studies show that SM contractile proteins are re-expressed in the neointima, concomitant with late lumen loss. Therefore one important question is whether the restoration of contractile phenotype, which can suppress VSMC migration, is favourable or detrimental. In this review, the importance of viewing restenosis as a multistage process is discussed. Different stages of restenosis occur in a sequential manner and are related to each other, but in each stage a different strategy should be taken into consideration to reduce restenosis. Defining the role of each process not only reshapes the current concept, but also helps us to target restenosis with more efficacy.


Subject(s)
Angioplasty, Balloon, Coronary/adverse effects , Coronary Restenosis/prevention & control , Animals , Constriction, Pathologic , Coronary Restenosis/etiology , Coronary Restenosis/pathology , Coronary Vessels , Humans , Muscle Contraction/physiology , Muscle, Smooth, Vascular/injuries , Muscle, Smooth, Vascular/pathology , Signal Transduction/physiology , rho-Associated Kinases/metabolism
10.
Mcgill J Med ; 11(2): 119-23, 2008 Jul.
Article in English | MEDLINE | ID: mdl-19148309

ABSTRACT

BACKGROUND: Vascular smooth muscle cell (VSMC) migration is integral in the pathogenesis of atherosclerosis. Sumac (Rhus coriaria) berries are believed to have atheroprotective effects. Therefore, Sumac, which is a rich source of tannin antioxidants, was tested for its capacity to inhibit VSMC migratory activity. MATERIALS & METHODS: Tannin was extracted and purified from ground Sumac. Cultured rat carotid VSMCs were treated with different concentrations of tannin. After 10 days of tannin treatment, VSMC migratory activity in response to platelet-derived growth factor-BB was measured by transmembrane migration assay. An equal number of VSMCs was loaded on top of the inserts and at the bottom of the wells. After fixation and staining, cells migrating through the inserts and cells seeded at the bottom of the wells were counted. RESULTS: A significant reduction (62%) of VSMC migration was evident in tannin-treated cells. To rule out any possible toxicity and cell death, cells at the bottom of the wells were also counted. No difference between the tannin-treated group and the controls was observed in the number of cells seeded at the bottom of the wells. CONCLUSION: Our data suggest that tannin extracted from Sumac possesses potent antimigratory activity. Sumac may have potential for the prevention or treatment of atherosclerosis and its clinical manifestations. Further experiments, especially in vivo, are required to examine the atheroprotective effect of Sumac.

11.
Cardiovasc Pathol ; 16(4): 212-20, 2007.
Article in English | MEDLINE | ID: mdl-17637429

ABSTRACT

INTRODUCTION: Constrictive remodeling of the neointima results in the late lumen loss and restenosis after balloon angioplasty. Intense expression of alpha8beta1 integrin in the contractile state of vascular smooth muscle cells (VSMCs) and in myofibroblasts led us to hypothesize that it might be involved in the process of late constrictive remodeling. METHODS AND RESULTS: Balloon injury was used to induce neointima formation in the rat carotid artery. Immunohistochemical analysis and immunoconfocal studies showed that late lumen narrowing was concomitant with the up-regulation of smooth muscle alpha-actin and alpha8 integrin in the neointima. The transforming growth factor-beta (TGF-beta)-induced contractile properties of fibroblasts and VSMCs populated in a three-dimensional collagen matrix was associated with up-regulation of alpha8 integrin. TGF-beta-induced myofibroblastic features in Rat1 fibroblasts were impaired in cells pretreated with a small interference RNA silencing the alpha8 integrin gene. CONCLUSION: The close correlation between alpha8 integrin up-regulation in the neointima and late luminal loss and alpha8 integrin being required for contractile properties induced by TGF-beta highlight a possible role for alpha8 integrin in postangioplasty restenosis.


Subject(s)
Carotid Stenosis/metabolism , Carotid Stenosis/pathology , Integrins/metabolism , Tunica Intima/metabolism , Tunica Intima/pathology , Animals , Carotid Artery Injuries/etiology , Carotid Artery Injuries/metabolism , Carotid Artery Injuries/pathology , Carotid Stenosis/etiology , Catheterization/adverse effects , Immunohistochemistry , Male , Microscopy, Confocal , Muscle Contraction/physiology , Muscle, Smooth, Vascular/metabolism , Rats , Rats, Sprague-Dawley , Up-Regulation
12.
FEBS Lett ; 581(5): 939-43, 2007 Mar 06.
Article in English | MEDLINE | ID: mdl-17300786

ABSTRACT

alpha8 integrin gene silencing has been shown to result in the stress fibre disassembly. Stress fibres are required for cell adhesion to promote passage through cell cycle. Thus, we hypothesized that alpha8 integrin gene silencing might affect vascular smooth muscle cell (VSMC) growth. Short interference RNA (siRNA) targeting alpha8 integrin in rat VSMCs resulted in reduced DNA synthesis. Moreover, siRNA-alpha8 integrin prevented thrombin-induced proliferation. RhoA plays a critical role in regulating VSMC growth. alpha8 integrin co-immunoprecipitated with RhoA and siRNA-alpha8 reduced membrane associated RhoA. Our data suggest that alpha8 integrin expression is critical for VSMC growth, which has potential implications in postangioplasty neointimal hyperplasia.


Subject(s)
Integrin alpha Chains/antagonists & inhibitors , Myocytes, Smooth Muscle/cytology , Myocytes, Smooth Muscle/metabolism , Animals , Base Sequence , Cell Division/drug effects , Cells, Cultured , DNA/biosynthesis , DNA Primers/genetics , Integrin alpha Chains/genetics , Integrin alpha Chains/metabolism , Myocytes, Smooth Muscle/drug effects , RNA Interference , Rats , Thrombin/pharmacology , rhoA GTP-Binding Protein/metabolism
13.
Atherosclerosis ; 195(2): 303-12, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17275006

ABSTRACT

Loss of the differentiated (contractile) phenotype of vascular smooth muscle cells (VSMCs) heightens their migratory activity. Integrins, as the main integrators of cell-extracellular matrix, regulate different aspects of cell behavior including migration and differentiation. alpha 8 beta 1 Integrin being expressed in cell types with contractile abilities is downregulated during VSMC phenotype modulation. In this report the ability of alpha 8 beta 1 integrin to induce the characteristics of the contractile phenotype as well as suppression of VSMC migratory activity was investigated. Forced expression of alpha 8 integrin in passage-5 rat VSMCs resulted in lower migratory activity. Western blot and immunoconfocal studies revealed that alpha 8 integrin overexpression was associated with the reappearance of VSMC contractile hallmarks including upregulation of contractile markers, assembly of stress fibres, and increased number of focal adhesions. alpha 8 Integrin overexpression in fibroblast-like Rat1 cells also induced SMC-like characteristics. alpha 8 Integrin-induced reappearance of the contractile hallmarks in de-differentiated VSMCs was impaired by RhoA inhibitors. These results provide evidences that alpha 8 integrin overexpression may assist phenotype-modulated VSMCs to revert to the contractile phenotype possibly via RhoA signaling pathway. Our findings suggest a dynamic role for alpha 8 beta 1 integrin to induce contractile phenotype as well as suppression of VSMC migration, a key player during arterial stenosis.


Subject(s)
Actins/physiology , Cell Differentiation/physiology , Cell Movement/physiology , Integrin alpha Chains/metabolism , Muscle, Smooth, Vascular/metabolism , Myocytes, Smooth Muscle/physiology , Animals , Cells, Cultured , Cytoskeleton/physiology , Fibroblasts/physiology , Microscopy, Confocal , Muscle Contraction/physiology , Muscle, Smooth, Vascular/cytology , Phenotype , Rats , Signal Transduction , Up-Regulation , rhoA GTP-Binding Protein/physiology
14.
Cardiovasc Res ; 71(1): 170-8, 2006 Jul 01.
Article in English | MEDLINE | ID: mdl-16603140

ABSTRACT

OBJECTIVE: Vascular smooth muscle cell (VSMC) de-differentiation is a prerequisite for migration from the tunica media to the intima after vascular injury. Integrin cell adhesion molecules participate in VSMC phenotype modulation. Alpha 8 beta 1 integrin is a differentiation marker of VSMCs and its knockdown heightens migration. In the present study, we examined whether or not alpha 8 integrin is required for the maintenance of VSMC differentiated phenotype. METHODS: Alpha 8 integrin in rat VSMC was knocked down by short interference RNA (siRNA) targeting alpha 8 integrin in comparison to a non-silencing siRNA. Cytoskeletal and morphological changes in VSMC were examined by immunofluorescence staining. The expression of phenotype-dependent markers was analyzed by immunoblotting. RESULTS: Alpha 8 integrin gene silencing evoked drastic changes in characteristics of the VSMC differentiated phenotype, including VSMC morphology, actin fibre organization, focal adhesion assembly and the expression of phenotype-dependent markers in favor of de-differentiation. Then, we investigated whether or not phenotype modulation induced by alpha 8 integrin gene silencing could be reversed by an inducer of VSMC differentiation. Transforming growth factor-beta (TGF-beta) failed to upregulate smooth muscle-myosin heavy chain as well as the assembly of parallel actin fibres in VSMCs transfected by siRNA-alpha 8. In addition, TGF-beta-induced vinculin localization at the tip of the cells was impaired by alpha 8 integrin gene silencing. CONCLUSION: These data suggest that alpha 8 integrin expression is required for maintenance of the VSMC differentiated phenotype, a state that is crucial for non-motile VSMCs.


Subject(s)
Integrin alpha Chains/metabolism , Muscle, Smooth, Vascular/metabolism , Myocytes, Smooth Muscle/metabolism , Actins/analysis , Actins/metabolism , Animals , Biomarkers/analysis , Blotting, Western/methods , Carotid Arteries , Cell Differentiation , Cell Movement , Cells, Cultured , Fluorescent Antibody Technique , Gene Targeting , Integrin alpha Chains/genetics , Male , Microscopy, Confocal , Muscle, Smooth, Vascular/cytology , Myosin Heavy Chains/analysis , Myosin Heavy Chains/metabolism , Phenotype , RNA Interference , RNA, Small Interfering/metabolism , Rats , Rats, Sprague-Dawley , Tumor Necrosis Factor-alpha/metabolism , Tumor Necrosis Factor-alpha/pharmacology , Tunica Intima/cytology , Tunica Intima/metabolism , Vinculin/analysis , Vinculin/metabolism
15.
Cardiovasc Res ; 65(4): 813-22, 2005 Mar 01.
Article in English | MEDLINE | ID: mdl-15721861

ABSTRACT

OBJECTIVE: Migration of vascular smooth muscle cells (VSMCs) from the tunica media to the intima is a key event in neointima formation after coronary artery angioplasty. The central dogma in VSMC migration is cell modulation from the contractile to the noncontractile phenotype. Increased alpha8beta1 integrin expression, observed in situations where the majority of cells are in the contractile phenotype, led us to hypothesize that a decrease of alpha8beta1 integrin may play an important role in the migratory state of VSMCs. METHODS AND RESULTS: To test this hypothesis, neointima formation was induced in the left common carotid artery of adult male Sprague-Dawley rats by balloon dilatation. Immunohistochemical and Western blotting analysis showed reduced expression for up to 4 weeks of both the alpha8 and beta1 integrin subunits as well as smooth muscle alpha-actin in the tunica media following balloon injury. Moreover, ex vivo culture of carotid VSMCs revealed diminished alpha8 integrin expression in the platelet-derived growth-factor-dependent migratory state with an increase in the angiotensin-II-induced contractile state. To ascertain the functional role of alpha8 integrin in VSMC migration and proliferation, alpha8 gene expression was reduced by nearly 70% by short interference RNA (siRNA). Decreased alpha8 expression resulted in a significant increase of carotid VSMC migration but not of proliferation. CONCLUSIONS: Our results are consistent with those of other studies demonstrating that alpha8 integrin could be used as an appropriate differentiation marker. In addition, depressed alpha8 integrin expression (after vascular injury or siRNA knockdown) was correlated with heightened cell migratory activity, demonstrating its potential role in neointima formation.


Subject(s)
Carotid Artery Injuries/metabolism , Carotid Artery, Common/metabolism , Integrins/metabolism , Muscle, Smooth, Vascular/pathology , Tunica Intima/pathology , Angioplasty, Balloon/adverse effects , Animals , Carotid Artery Injuries/pathology , Carotid Artery, Common/pathology , Cell Differentiation , Cell Movement , Cells, Cultured , Disease Models, Animal , Down-Regulation , Integrins/genetics , Integrins/physiology , Male , Muscle, Smooth, Vascular/injuries , Muscle, Smooth, Vascular/metabolism , RNA, Small Interfering/genetics , Rats , Rats, Sprague-Dawley , Transfection , Tunica Intima/metabolism
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