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Psoriasis , Humanos , Enfermedad Aguda , Causalidad , Enfermedad Crónica , Psoriasis/epidemiología , Psoriasis/genética , Pirina/genéticaRESUMEN
Palmoplantar pustulosis (PPP) is a rare chronic pustular condition that affects the palms and soles. Smoking and focal infections and dental metal allergies are risk factors for PPP development. Here we report a case of a 60-year-old woman who experienced a relapse of PPP after receiving the COMIRNATY vaccine against COVID-19. The patient relapsed after being in remission for seven years. This article shows the possible implications of COVID-19 vaccination related to the relapse of previous diseases and stresses the importance of careful observation of post-vaccination occurrences of skin eruptions, especially in patients having a history of PPP.
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The Runt-related transcription factor (Runx) family has been suggested to play roles in stem cell regulation, tissue development, and oncogenesis in various tissues/organs. In this study, we investigated the possible functions of Runx1 and Runx3 in keratinocyte differentiation. Both Runx1 and Runx3 proteins were detected in primary cultures of mouse keratinocytes. Proteins were localized in the nuclei of undifferentiated keratinocytes but translocated to the cytoplasm of differentiated cells. The siRNA-mediated inhibition of Runx1 and Runx3 expression increased expression of keratin 1 and keratin 10, which are early differentiation markers of keratinocytes. In contrast, overexpression of Runx1 and Runx3 suppressed keratin 1 and keratin 10 expression. Endogenous Runx1 and Runx3 proteins were associated with the promoter sequences of keratin 1 and keratin 10 genes in undifferentiated but not differentiated keratinocytes. In mouse skin, the inhibition of Runx1 and Runx3 expression by keratinocyte-specific gene targeting increased the ratios of keratin 1- and keratin 10-positive cells in the basal layer of the epidermis. On the other hand, inhibition of Runx1 and Runx3 expression did not alter the proliferation capacity of cultured or epidermal keratinocytes. These results suggest that Runx1 and Runx3 likely function to directly inhibit differentiation-induced expression of keratin 1 and keratin 10 genes but are not involved in the regulation of keratinocyte proliferation.
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Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Subunidad alfa 3 del Factor de Unión al Sitio Principal/metabolismo , Queratina-10 , Queratina-1 , Animales , Diferenciación Celular , Queratina-1/genética , Queratina-10/genética , Queratinocitos/metabolismo , Queratinas/genética , RatonesRESUMEN
Pain, stiffness, and swelling are the main joint symptoms of psoriatic arthritis (PsA); however, they are also common symptoms of other joint diseases. Therefore, it is challenging to distinguish PsA from other joint diseases. To evaluate the prevalence of PsA and the frequency of joint symptoms in psoriasis patients, we conducted a prefecture-wide survey using the Psoriasis Epidemiology Screening Tool (PEST), a patient questionnaire for screening PsA to assess joint symptoms. Data were collected from 764 psoriasis patients, all of whom visited hospitals (55.1%) or clinics (44.9%) in Nagano Prefecture, Japan. The proportion of psoriasis patients with PsA was 6.5% (50 of 764); four patients (1.2%) with PsA were treated in clinics, while 46 patients (10.9%) were treated in hospitals. Based on the responses to the PEST, 18.1% of patients with psoriasis had joint symptoms. In contrast, 73.2% of psoriasis patients with joint symptoms did not have PsA. The PEST showed 52% sensitivity and 93.4% specificity for PsA. In addition, fingernail alterations were common in PsA. The proportion of the population with PsA was lower than reported previously in Japan. This may have been due to the enrollment of a large number of patients treated in clinics. Many patients with PsA were treated at hospitals, which likely reflects the tendency of patients with joint symptoms to receive intensive treatment in hospitals. In addition, based on the lower sensitivity of the PEST in this study, further studies are necessary to establish the validity of the PEST.
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Artritis Psoriásica , Psoriasis , Artritis Psoriásica/complicaciones , Artritis Psoriásica/diagnóstico , Artritis Psoriásica/epidemiología , Humanos , Japón/epidemiología , Prevalencia , Psoriasis/complicaciones , Psoriasis/diagnóstico , Psoriasis/epidemiología , Encuestas y CuestionariosRESUMEN
Primary cutaneous melanoma generally arises in the epidermis, followed by invasion into the dermis. Although infrequent, invasive melanoma cells can, alternatively, migrate to the intraepidermal area and form epidermotropic melanoma metastasis (EMM). In this study, we focused on this unique manner of metastasis. To identify the key molecules which affect EMM, gene expression in EMM was compared with that in common skin metastasis (CSM). Polymerase chain reaction (PCR) analysis was performed for genes affecting the extracellular matrix, cellular adhesion, and tumor metastasis on three EMM and three CSM samples as an initial screening. For molecules showing altered expression in the EMM, expression levels were further verified using real-time quantitative PCR (qPCR) and immunohistochemistry. Five molecules showed an expression difference in the initial screening. Among these, secreted protein acidic and rich in cysteine (SPARC) was preferentially expressed in EMM (p = 0.01) by real-time qPCR. Another candidate molecule, tissue inhibitor of metalloproteinase-3 (TIMP3), was not statistically significant (p = 0.07), but showed the tendency of higher expression. These results correlated negatively to expression of N-cadherin and ß-catenin. The upregulation of SPARC and TIMP3 may disrupt the continuity of the canonical Wnt pathway. This pathway regulates adhesion activity of melanoma cells to localize within the dermis, which consequently promotes EMM. Our study highlights the potential role of SPARC and TIMP3 as key molecules in EMM, and analysis of EMM may contribute for understanding melanoma invasion between the epidermis and the dermis.
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Melanoma , Neoplasias Cutáneas , Antígenos CD , Cadherinas , Línea Celular Tumoral , Cisteína , Humanos , Melanoma/genética , Osteonectina/genética , Neoplasias Cutáneas/genética , Inhibidor Tisular de Metaloproteinasa-3/genética , beta CateninaRESUMEN
OBJECTIVES: PsA is characterized by enthesitis, synovitis and osseous involvement in the peripheral and axial joints. Few studies have examined axial involvement in PsA using imaging techniques. Here we examined axial involvement in PsA patients using MRI. In addition, we determined the efficacy of 24 week adalimumab treatment in improving the MRI findings of spondylitis and sacroiliitis. METHODS: This was a prospective, open-label, single-arm study in patients with PsA. Adalimumab was administered to patients for a total of 24 weeks. MRI examinations were conducted at baseline and at week 24 of adalimumab treatment. RESULTS: Thirty-seven patients with PsA were included in this study. Spondylitis was observed in at least one site of the positive scan in 91% (n = 31) of patients with PsA. The number of arthritic sites in the cervical, thoracic and lumbar regions of the spine was 48, 67 and 53, respectively. All patients had MRI-determined sacroiliitis of grade ≥1 severity while 28 patients (82%) had grade ≥2 sacroiliitis in at least one sacroiliac region. Sacroiliac arthritis was statistically more severe on the right side than on the left side (P < 0.05). In 34 patients with PsA, the thoracic spine was the most common site of spondylitis. In addition, 24 week adalimumab treatment led to an improvement in the mean number of spondylitis sites and the mean grade of sacroiliitis. CONCLUSION: Treatment with adalimumab for 24 weeks resulted in improvement in spondylitis and sacroiliitis.
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Adalimumab/uso terapéutico , Antirreumáticos/uso terapéutico , Artritis Psoriásica/tratamiento farmacológico , Adulto , Anciano , Artritis Psoriásica/diagnóstico por imagen , Artritis Psoriásica/fisiopatología , Femenino , Humanos , Japón , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sacroileítis/diagnóstico por imagen , Sacroileítis/fisiopatología , Espondilitis/diagnóstico por imagen , Espondilitis/fisiopatología , Vértebras Torácicas/diagnóstico por imagenRESUMEN
Psoriasis is a chronic inflammatory skin condition caused by a combination of hereditary and environmental factors. Its development is closely related to the adaptive immune response. T helper 17 cells are major IL-17-producing cells, a function that plays an important role in the pathogenesis of psoriasis. However, recent findings have demonstrated that innate immune cells also contribute to the development of psoriasis. Innate lymphoid cells, γδ T cells, natural killer T cells, and natural killer cells are activated in psoriasis, contributing to disease pathology through IL-17-dependent and -independent mechanisms. The present review provides an overview of recent findings, demonstrating a role for innate immunity in psoriasis.
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Linfocitos/fisiología , Psoriasis/inmunología , Humanos , Inmunidad InnataRESUMEN
Objectives: To evaluate the efficacy and safety of adalimumab in psoriatic arthritis (PsA) patients in Japan.Methods: In this open-label, single-arm study conducted at six sites from October 2014 to June 2016 (UMIN000016543), PsA patients (≥20 years old) with inadequate response to nonsteroidal anti-inflammatory drugs received adalimumab subcutaneously (80 mg initially, then 40 mg every other week; 24 weeks total). Primary endpoint was American College of Rheumatology 20% improvement (ACR20) response rate at week 12.Results: Of 42 enrolled patients, 37 were treated (mean (SD) age, 56.2 (13.0) years; male, 27 (73.0%)). ACR20, ACR50, and ACR70 response rates were 40.5%, 24.3%, and 16.2% at week 12 and increased to 45.9%, 37.8%, and 21.6% at week 24, respectively. Psoriasis Area and Severity Index (PASI) 50 response rates were unchanged at weeks 12 and 24 (73%), but PASI75 and PASI90 increased from 40.5% and 21.6% to 59.5% and 40.5%, respectively. Other indices such as Physician's Global Assessment score, C-reactive protein-based disease activity score in 28 joints, Bath Ankylosing Spondylitis Disease Activity Index, and serum biomarker levels were significantly improved. No unexpected adverse events were reported.Conclusion: Similar to the global population, adalimumab was efficacious and well tolerated in Japanese treatment-experienced PsA patients.
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Adalimumab/uso terapéutico , Antiinflamatorios no Esteroideos/uso terapéutico , Artritis Psoriásica/tratamiento farmacológico , Antirreumáticos/uso terapéutico , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Resultado del TratamientoAsunto(s)
Pancreatitis/complicaciones , Psoriasis/complicaciones , Administración Cutánea , Antibacterianos/uso terapéutico , Profilaxis Antibiótica/métodos , Calcio/sangre , Preescolar , Fármacos Dermatológicos/administración & dosificación , Dihidroxicolecalciferoles/administración & dosificación , Humanos , Masculino , Páncreas/diagnóstico por imagen , Pancreatitis/sangre , Pancreatitis/diagnóstico por imagen , Pancreatitis/tratamiento farmacológico , Psoriasis/sangre , Psoriasis/diagnóstico , Psoriasis/tratamiento farmacológico , Tomografía Computarizada por Rayos XRESUMEN
A local epidemiological survey of psoriasis was conducted from 19 February to 30 June 2016 in Matsumoto city, Nagano Prefecture, Japan. Patients were predominantly male (268 cases, 71.5% males vs 107 cases, 28.5% females). We estimated that the prevalence of psoriasis was 0.097% in the Matsumoto area. The clinical types of psoriasis identified were psoriasis vulgaris (90.7%), psoriatic arthritis (5.9%), pustular psoriasis (2.1%), guttate psoriasis (1.0%) and psoriatic erythroderma (0.3%). The topical therapeutic agents included corticosteroids (84.0%), vitamin D3 analogs (61.5%), and a combination of calcipotriol and betamethasone dipropionate (31.0%). Current systemic treatments included cyclosporin (9.0%), etretinate (7.4%) and methotrexate (1.3%). Biologic treatments included adalimumab (4.0%), ustekinumab (2.7%), infliximab (1.3%) and secukinumab (0.8%). Ultraviolet B therapy (11.3%) was the predominant phototherapy in which narrow band ultraviolet B therapy accounted for the majority, followed by psoralen and ultraviolet A therapy (1.0%). According to the recent evolution of psoriasis treatment, the use of biologics has been increasing. This study demonstrates the changes of treatment trends of psoriasis in a non-metropolitan regional area.
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Productos Biológicos/uso terapéutico , Encuestas Epidemiológicas/estadística & datos numéricos , Psoriasis/epidemiología , Terapia Ultravioleta/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Prevalencia , Psoriasis/terapia , Terapia Ultravioleta/estadística & datos numéricos , Adulto JovenRESUMEN
The pathogenesis of psoriasis can be explained by dysregulation of immunological cell function as well as keratinocyte proliferation/differentiation. Recently, the immunological pathomechanism has been clarified substantially. Whereas T-helper (Th)1 overactivation was thought to induce occurrence of psoriasis, it has been demonstrated that Th17 cells play a key role. Th17 development is maintained by interleukin (IL)-23 mainly produced by dendritic cells. Th17 cells produce various cytokines, including IL-17A, IL-17F and IL-22. IL-17A and IL-22 induce not only keratinocyte proliferation, but also tumor necrosis factor (TNF)-α, chemokine (C-X-C motif) ligand (CXCL)1 and CXCL8 production. TNF-α accelerates the infiltration of inflammatory cells, including lymphocytes, monocytes and neutrophils, from the peripheral blood into skin with dendritic cell activation. In addition, antimicrobial peptides are overexpressed in psoriatic skin lesions, and the antimicrobial peptide, LL-37, activates dendritic cells, which leads to the development of inflammation. Furthermore, activation of nuclear factor-κB signal induces the expression of keratins 6 and 16 in keratinocytes, which are associated with acanthosis and reduced turnover time in the epidermis. The progression of the pathomechanism contributes to the development of new therapies for psoriasis.
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Citocinas/inmunología , Fármacos Dermatológicos/uso terapéutico , Epidermis/inmunología , Queratinocitos/inmunología , Psoriasis/inmunología , Productos Biológicos/uso terapéutico , Proliferación Celular , Ciclosporina/uso terapéutico , Citocinas/metabolismo , Defensinas/inmunología , Defensinas/metabolismo , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Células Epidérmicas , Epidermis/metabolismo , Humanos , Queratinocitos/metabolismo , Inhibidores de Fosfodiesterasa 4/uso terapéutico , Psoriasis/tratamiento farmacológico , Psoriasis/genética , Retinoides/uso terapéutico , Linfocitos T Colaboradores-Inductores/inmunología , Linfocitos T Colaboradores-Inductores/metabolismoRESUMEN
The etiology of polyarteritis nodosa (PAN) and localized PAN is still unknown, although a T cell-mediated immune mechanism has been considered. CD8 T cells participate not only in the antigen-dependent adaptive immune system, but also in the antigen-independent innate immune system. Non-antigen-activated CD8 T cells express a unique phenotype: granzyme B (GrB) positive /CD25 negative /programmed death-1 (PD-1) negative. The aims of this study were to assess the participation of T cells, especially innate CD8 T cells, in the development of vasculitis. Twenty-eight consecutive cases of skin biopsy specimens with cutaneous vasculitis of small muscular arteries (CVSMA) were retrieved. The series comprises of 21 cases of cutaneous arteritis, three cases of PAN, and four cases of rheumatoid vasculitis. Cases of antineutrophil cytoplasmic antibody-associated vasculitis were excluded. The phenotypes of infiltrating lymphocytes in vasculitis lesions were evaluated by immunohistochemistry. In most cases of CVSMA, the number of CD8 T cells infiltrating the intima was higher than that of CD4 T cells, and significant numbers of GrB-positive cells, which represent activated CD8 T cells, were observed. However, GrB/CD25-double-positive cells, which correspond to antigen-activated T cells, were very few in a small number of cases. Cells positive for PD-1, which is also expressed on antigen-activated CD8 T cells, were not detected. We conclude that a T cell-mediated immune mechanism, involving cytotoxic CD8 T cells, may play a role in the development of CVSMA. Low expression of CD25 in activated CD8 T cells suggests that activation was antigen-independent.
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Antígenos/inmunología , Linfocitos T CD8-positivos/inmunología , Activación de Linfocitos/inmunología , Poliarteritis Nudosa/inmunología , Vasculitis Reumatoide/inmunología , Piel/inmunología , Adulto , Anciano , Arterias/inmunología , Arterias/patología , Femenino , Humanos , Inmunidad Innata , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Poliarteritis Nudosa/patología , Vasculitis Reumatoide/patología , Piel/irrigación sanguínea , Piel/patologíaRESUMEN
Atopic dermatitis is increasing worldwide in correlation with air pollution. Various organic components of pollutants activate the transcription factor AhR (aryl hydrocarbon receptor). Through the use of AhR-CA mice, whose keratinocytes express constitutively active AhR and that develop atopic-dermatitis-like phenotypes, we identified Artn as a keratinocyte-specific AhR target gene whose product (the neurotrophic factor artemin) was responsible for epidermal hyper-innervation that led to hypersensitivity to pruritus. The activation of AhR via air pollutants induced expression of artemin, alloknesis, epidermal hyper-innervation and inflammation. AhR activation and ARTN expression were positively correlated in the epidermis of patients with atopic dermatitis. Thus, AhR in keratinocytes senses environmental stimuli and elicits an atopic-dermatitis pathology. We propose a mechanism of air-pollution-induced atopic dermatitis via activation of AhR.
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Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Dermatitis Atópica/inmunología , Epidermis/inervación , Queratina-15/metabolismo , Queratinocitos/fisiología , Proteínas del Tejido Nervioso/metabolismo , Prurito/inmunología , Receptores de Hidrocarburo de Aril/metabolismo , Contaminantes Atmosféricos/efectos adversos , Animales , Animales Recién Nacidos , Orientación del Axón/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Células Cultivadas , Epidermis/patología , Regulación de la Expresión Génica , Humanos , Queratina-15/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas del Tejido Nervioso/genética , Receptor EphB2/genética , Receptor EphB2/metabolismo , Receptores de Hidrocarburo de Aril/genéticaAsunto(s)
Receptores ErbB/antagonistas & inhibidores , Clorhidrato de Erlotinib/toxicidad , FN-kappa B/agonistas , PPAR gamma/agonistas , Inhibidores de Proteínas Quinasas/toxicidad , Quinazolinas/toxicidad , Glándulas Sebáceas/efectos de los fármacos , Enfermedades Cutáneas Papuloescamosas/inducido químicamente , Factor de Necrosis Tumoral alfa/metabolismo , Línea Celular , Receptores ErbB/metabolismo , Gefitinib , Humanos , FN-kappa B/metabolismo , PPAR gamma/metabolismo , Glándulas Sebáceas/metabolismo , Glándulas Sebáceas/patología , Transducción de Señal , Enfermedades Cutáneas Papuloescamosas/metabolismo , Enfermedades Cutáneas Papuloescamosas/patología , Factores de Tiempo , Regulación hacia ArribaAsunto(s)
5-Metilcitosina/análogos & derivados , Adenoma/diagnóstico , Biomarcadores de Tumor/análisis , Neoplasias de la Mama/diagnóstico , Pezones/química , Pezones/patología , 5-Metilcitosina/análisis , Adenoma/patología , Adenoma/cirugía , Adulto , Biopsia con Aguja , Neoplasias de la Mama/patología , Neoplasias de la Mama/cirugía , Femenino , Humanos , Biopsia Guiada por Imagen , Inmunohistoquímica , Imagen por Resonancia Magnética , Persona de Mediana EdadRESUMEN
BACKGROUND: Notch signaling controls a number of cellular processes, including cell fate decisions, proliferation, differentiation, and survival/apoptosis, in multiple tissues. In the epidermis, Notch1 functions as a molecular switch that controls the transition of cells from an undifferentiated state into a differentiated state. OBJECTIVE: To clarify the functions of Notch in the regenerated epidermis during wound healing. METHODS: Wounds on mouse skin were immunostained. To investigate the functions of Notch, Notch was inhibited in primary keratinocytes by treatment with a γ-secretase inhibitor and by small interfering RNA-mediated knockdown, and was activated by a recombinant adenovirus approach. RESULTS: Notch1 and Notch2 were down-regulated in the regenerated epidermis during wound healing. To clarify the significance of this down-regulation, we examined its effect on expression of the interleukin (IL)-1 family of proinflammatory cytokines because wounds are exposed to pathogens from the outside world. Among the IL-1 family, IL-36α expression was induced by Notch inhibition. This was consistent with the decreased IL-36α expression in Notch-overexpressing keratinocytes. Notch down-regulation in the regenerated epidermis may reinforce defense against stress from the outside world by inducing IL-36α expression. Next, we examined the effects of Notch down-regulation on keratinocyte growth and differentiation. Notch down-regulation did not alter keratinocyte proliferation. On the other hand, Notch1 down-regulation suppressed induction of spinous layer-specific keratins (keratin1 and keratin10) in keratinocytes, which was consistent with the decreased expression of these keratins in the regenerated epidermis. The reduced levels of these keratins would increase cellular flexibility. CONCLUSION: Notch down-regulation in the epidermis appears to contribute to tissue regeneration during wound healing.
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Epidermis/metabolismo , Interleucina-1/metabolismo , Receptor Notch1/metabolismo , Receptor Notch2/metabolismo , Cicatrización de Heridas/fisiología , Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Animales , Diferenciación Celular , Proliferación Celular , Células Cultivadas , Dipéptidos/farmacología , Regulación hacia Abajo , Inhibidores Enzimáticos/farmacología , Femenino , Técnicas de Silenciamiento del Gen , Interleucina-1/genética , Queratina-1/metabolismo , Queratina-10/metabolismo , Queratinocitos/fisiología , Ratones , Ratones Endogámicos C57BL , ARN Mensajero/metabolismo , Receptor Notch1/genética , Receptor Notch2/genética , Regeneración , Transducción de Señal/efectos de los fármacos , Cicatrización de Heridas/efectos de los fármacosRESUMEN
Immune cell Toll-like receptors (TLRs) recognize conserved microbial components, leading to immune and inflammatory responses. However, TLRs are also expressed in cancer cells, including melanoma cells, which express TLR2-4. TLR4 ligands have received attention as immunotherapies; therefore, we assessed the expression of TLR4 in human melanoma specimens (29 primary lesions and 28 metastatic lesions) representing different types of melanoma. A high percentage (≥ 90%) of melanoma lesions expressed TLR4, as judged by immunohistochemistry. Next, the role of TLR4 in cell proliferation and migration was assessed using the TLR4-positive (TLR4(+)) melanoma cell lines 501mel and 888mel, and TLR4-negative (TLR4(â)) 928mel melanoma cells. Lipopolysaccharide (LPS), a TLR4 agonist, increased the proliferation of TLR4(+) melanoma cells but not of TLR4(â) 928mel cells. The proliferation-inducing effect of LPS in 888mel cells was abolished by blockade of TLR4 signaling via treatment with short interfering RNA (siRNA) targeting TLR4 or myeloid differentiation primary response gene 88 (MyD88), a molecule downstream of TLR4. However, knockdown of TLR4 or MyD88 expression did not affect the LPS-induced proliferation of 501mel cells, suggesting that residual TLR4 signaling is sufficient to maintain cell proliferation. By contrast, LPS increased the migration of TLR4(+) melanoma cells, and this effect was substantially inhibited by TLR4 or MyD88 knockdown. Furthermore, TLR4 knockdown decreased cell migration even in the absence of LPS, suggesting the presence of an endogenous TLR4 ligand(s) in melanoma cells. TLR4 signaling may contribute to melanoma progression, and caution should be exercised when using TLR4 ligands as adjuvant therapy for cancer.
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Movimiento Celular/fisiología , Melanoma/fisiopatología , Transducción de Señal/fisiología , Receptor Toll-Like 4/metabolismo , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Proliferación Celular/fisiología , Humanos , Inmunohistoquímica , Lipopolisacáridos/farmacología , Factor 88 de Diferenciación Mieloide/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Receptor Toll-Like 4/agonistasRESUMEN
BACKGROUND: Characterization of the MAPK signaling pathway in melanoma has led to the development of MEK inhibitors for the treatment of NRAS-mutated melanoma. The success of molecular-targeted therapies underscores the need to identify mutations in target genes. Most of the current data on genetic mutations have been obtained from Caucasian melanoma patients, and screenings of Asian populations are limited. OBJECTIVE: The aim of the present study was to examine NRAS mutations in primary and metastatic lesions of Japanese melanoma patients. METHODS: Clinical melanoma specimens were collected from 127 Japanese patients, including primary (n = 67), metastatic (n = 25) and paired primary and metastatic lesions (n = 35). NRAS mutations in exons 1 and 2 were assessed by polymerase chain reaction and Sanger sequencing. RESULTS: The incidence of NRAS mutations was 7.1 %. NRAS (Q61) was the predominant genetic alteration (77.8 %). NRAS mutations were most frequently detected in acral melanomas (9.3 %), followed by melanomas without chronic sun-induced damage (7.0 %) and mucosal melanomas (4.8 %), and were not detected in melanomas with chronic sun-induced damage. In addition, NRAS mutations were more prevalent in the extremities than in other sites. The NRAS sequence in metastatic lesions did not match that of the primary tumor in one case. CONCLUSION: The frequency of NRAS mutations is lower in the Asian population than in Caucasian patients. The observed heterogeneity of melanoma suggests that genotyping of both primary and metastatic lesions is important to identify candidate patients for molecular-targeted therapies.