Etk/Bmx mediates expression of stress-induced adaptive genes VEGF, PAI-1, and iNOS via multiple signaling cascades in different cell systems.
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We recently showed that Etk/Bmx, a member of the Tec family of nonreceptor protein tyrosine kinases, promotes tight junction formation during chronic hypoxic exposure and augments normoxic VEGF expression via a feedforward mechanism. Here we further characterized Etk's role in potentiating hypoxia-induced gene expression in salivary epithelial Pa-4 cells. Using transient transfection in conditionally activated Etk (DeltaEtk:ER) cells, we demonstrated that Etk enhances hypoxia-response element-dependent reporter activation in normoxia and hypoxia. This Etk-driven reporter activation is ameliorated by treatment with wortmannin or LFM-A13. Using lentivirus-mediated gene delivery and small interfering RNA, we provided direct evidence that hypoxia leads to transient Etk and Akt activation and hypoxia-mediated Akt activation is Etk dependent. Northern blot analyses confirmed that Etk activation led to induction of steady-state mRNA levels of endogenous VEGF and plasminogen activator inhibitor (PAI)-1, a hallmark of hypoxia-mediated gene regulation. We also demonstrated that Etk utilizes a phosphatidylinositol 3-kinase/Akt pathway to promote reporter activation driven by NF-kappaB, another oxygen-sensitive transcription factor, and to augment cytokine-induced inducible nitric oxide synthase expression in endothelial cells. To establish the clinical relevance of Etk-induced, hypoxia-mediated gene regulation, we examined Etk expression in keloid, which has elevated VEGF and PAI-1. We found that Etk is overexpressed in keloid (but not normal skin) tissues. The differential steady-state Etk protein levels were further confirmed in primary fibroblast cultures derived from these tissues, suggesting an Etk role in tissue fibrosis. Our results provide further understanding of Etk function within multiple signaling cascades to govern adaptive cytoprotection against extracellular stress in different cell systems, salivary epithelial cells, brain endothelial cells, and dermal fibroblasts. (+info)
Global gene expression analysis of keloid fibroblasts in response to electron beam irradiation reveals the involvement of interleukin-6 pathway.
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Keloid is a dermal fibroproliferative lesion of unknown etiology that commonly recurs after surgical excision. Post-operative adjuvant electron beam (EB) irradiation has been successfully used to reduce keloid recurrences. To provide new insights into the molecular mechanism behind the effect of EB irradiation, we used a cDNA microarray screening of more than 5000 genes to assess early changes in gene expression between EB-irradiated and non-irradiated keloid and non-lesional dermal fibroblasts. Primary fibroblast cultures from keloid and associated non-lesional dermis obtained from five patients were exposed to 15 Gy EB irradiation and analyzed after 15 min incubation. Early response to EB irradiation showed that 96 (1.8%) genes were modulated 2-fold or more in keloid fibroblasts. Upregulated genes accounted for 29.2% (28 genes), whereas downregulated genes comprised 70.8% (68 genes), indicating a silencing of many genes in keloid fibroblasts after EB irradiation. Many of the downregulated genes play roles in the enhancement of cell proliferation and extracellular matrix production, whereas several of the upregulated genes involves in the promotion of apoptosis and extracellular matrix (ECM) degradation. Using emerging bioinformatic tools and further corroboration, the interleukin 6 (IL-6) signaling pathway was found to be mainly involved in EB irradiation response. We also showed co-expression of IL-6 and its specific receptor (IL-6Ralpha) in keloid fibroblasts that points to the existence of an IL-6 autocrine loop in these cells. These results suggested that at the molecular level, EB irradiation might hinder keloid formation by regularizing disturbances in the homeostatic equilibrium between inducer and inhibitor activities in the matrix system most likely through the IL-6 pathway. Our study provides clues for the molecular mechanism(s) behind the beneficial effect of EB irradiation in reducing keloid recurrences and may help develop alternative strategies for the therapy and prophylaxis of this lesion. (+info)
Consent to medical treatment.
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Obtaining patient consent is good medical practice and a legal necessity. This article examines the duty of general practitioners to obtain consent from patients for medical interventions and outlines the process of obtaining consent. (+info)
A case of congenital corneal keloid.
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PURPOSE: To describe a case of unilateral comeal keloid and present the clinical and histopathological findings and the management. METHODS: A 23-year-old Asian male patient was examined for a white spot on the left cornea that had been present since birth. On biomicroscopic examination, a well-demarcated vascularized comeal mass was found located nasal to the center. The pupil was displaced superiorly, and gonioscopic examination showed peripheral iridocomeal adhesion at 12 o'clock. The patient underwent penetrating keratoplasty. RESULTS: Histopathologic study showed a variously thickened epithelial layer, an absence of Bowman's layer, subepithelial fibrovascular hyperplasia, and an absence of dermal elements. These histopathologic findings suggested a congenital comeal keloid. The central graft comea remained clear at 18 months after surgery and the patient was satisfied with the result. CONCLUSIONS: Penetrating keratoplasty may be an effective surgical option for congenital keloids in young adult patients. (+info)
Keloid heterograft in the hamster (Mesocricetus auratus) cheek pouch, Brazil.
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PURPOSE: To study the integration of keloid heterograft in hamster (Mesocricetus auratus) cheek pouch. METHODS: The sample is formed by 18 male hamsters, heterogenic ones, aged between 10 and 14 weeks. Keloid fragments were obtained from keloid scars of the breast region of adult female mulatto patient. Each hamster received keloid fragments into both of its pouches, in a total of 36 grafted fragments. Animals were distributed into 6 groups for having their grafts assessed in the days 5, 12, 21,42, 84, and 168. A macroscopic assessment is performed by comparing the pouch containing the grafted fragment, at each time point, with the same pouch in the immediate post surgical moment through a comparison of standardized photographs. Under microscope, the presence of blood vases is considered within the conjunctive tissue of the grafted fragment, as a criterion of its integration. Other events, as keratin secretion, the presence of cellular infiltrated, epithelium and keloid collagen fibers aspects are also analyzed. RESULTS: Macroscopy reveals intensive vascularization of the pouch up to 12 days from the transplantation and the presence of constant dark brown pigmentation on the grafted keloid fragments. In microscopy, the integration of keloid fragments is considered by the presence of blood capillary vases within conjunctive tissue. The presence of intensive cellular inflammatory type infiltrated up to 12 days is also observed, as well as the remaining of keloid epithelium up to 21 days, and the appearing of melanocytes from the day 42. CONCLUSION: Hamster cheek pouch represents, a priori, an experimental model for the investigation of keloid. (+info)
Studies of transforming growth factors beta 1-3 and their receptors I and II in fibroblast of keloids and hypertrophic scars.
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Keloids are benign skin tumours occurring during wound healing in genetically predisposed patients. They are characterized by an abnormal deposition of extracellular matrix components, particularly collagen. There is uncertain evidence that transforming growth factor-beta (TGFss) is involved in keloid formation. Therefore we investigated the expression of TGFss1, 2 and 3 and their receptors in keloids, hypertrophic scars and normal skin. Dermal fibroblasts were obtained from punch biopsies of patients with keloids and hypertrophic scars and from normal skin of healthy individuals. Total RNA was isolated and the expression of TGFss1, 2 and 3 and of TGFss receptors I and II (TGFssRI and II) was analysed by real-time PCR using the Lightcycler technique. Our data demonstrate significantly lower TGFss2 mRNA expression in hypertrophic scar fibroblasts as compared with fibroblasts derived from keloids and normal skin (p<0.05). In contrast, TGFss3 mRNA expression was significantly lower in keloid fibroblasts in comparison with fibroblasts derived from hypertrophic scar and normal skin (p<0.01). TGFssRI mRNA expression was significantly decreased in hypertrophic scar fibroblasts (p<0.01) and TGFssRII mRNA expression was decreased in keloids compared with hypertrophic scar fibroblasts (p<0.001). The ratio of TGFssRI/TGFssRII expression was increased in keloids compared with hypertrophic scar and normal skin fibroblasts. As recently supposed, an increased TGFssRI/TGFssRII ratio could promote fibrosis. Therefore our data support a possible role of TGFssRI and TGFssRII in combination with a certain TGFss expression pattern as fibrosis-inducing factors in keloids. (+info)
Comparison of transforming growth factor-beta/Smad signaling between normal dermal fibroblasts and fibroblasts derived from central and peripheral areas of keloid lesions.
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BACKGROUND: Keloids are benign proliferations of fibroblasts, but their exact etiology and molecular pathogenesis are unknown. MATERIALS AND METHODS: Fibroblasts were isolated from the central and peripheral regions of keloids, and the growth behavior and molecular characteristics of the keloid fibroblasts were compared with those of age-adjusted normal dermal fibroblasts. RESULTS: Central (but not peripheral) keloid fibroblasts exhibited significantly increased growth and high levels of expression of transforming growth factor-beta (TGF-beta) receptor 1 and Smad 2/3. CONCLUSION: Proliferation of central keloid fibroblasts, which results in keloid formation, appears to mainly involve the TGF-beta/Smad pathway. (+info)
Treatment of keloids and hypertrophic scars.
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Clinicians always find it difficult to treat hypertrophic scars and keloids. Various treatment modalities are available. Intralesional corticosteroids, topical applications, cryotherapy, surgery, laser therapy, and silicone sheeting are the widely used options. Radiation therapy can also help in cases of recalcitrant keloids. Most recently, pulsed-dye laser has been successfully used to treat keloids and hypertrophic scars. There are no set guidelines for the treatment of keloids. Treatment has to be individualized depending upon the distribution, size, thickness, and consistency of the lesions and association of inflammation. A combination approach to therapy seems to be the best option. (+info)