RESUMEN
Sebum is a lipid-rich mixture secreted by the sebaceous gland (SG) onto the skin surface. By penetrating through the epidermis, sebum may be involved in the regulation of epidermal and dermal cells in both healthy and diseased skin conditions. Saturated and monounsaturated fatty acids (FAs), found as free FAs (FFAs) and in bound form in neutral lipids, are essential constituents of sebum and key players of the inflammatory processes occurring in the pilosebaceous unit in acne-prone skin. Little is known on the interplay among uptake of saturated FFAs, their biotransformation, and induction of proinflammatory cytokines in sebocytes. In the human SG, palmitate (C16:0) is the precursor of sapienate (C16:1n-10) formed by insertion of a double bond (DB) at the Δ6 position catalysed by the fatty acid desaturase 2 (FADS2) enzyme. Conversely, palmitoleate (C16:1n-7) is formed by insertion of a DB at the Δ9 position catalysed by the stearoyl coenzyme A desaturase 1 (SCD1) enzyme. Other FFAs processed in the SG, also undergo these main desaturation pathways. We investigated lipogenesis and release of IL-6 and IL-8 pro-inflammatory cytokines in SZ95 sebocytes in vitro after treatment with saturated FFAs, that is, C16:0, margarate (C17:0), and stearate (C18:0) with or without specific inhibitors of SCD1 and FADS2 desaturase enzymes, and a drug with mixed inhibitory effects on FADS1 and FADS2 activities. C16:0 underwent extended desaturation through both SCD1 and FADS2 catalysed pathways and displayed the strongest lipoinflammatory effects. Inhibition of desaturation pathways proved to enhance lipoinflammation induced by SFAs in SZ95 sebocytes. Palmitate (C16:0), margarate (C17:0), and stearate (C18:0) are saturated fatty acids that induce different arrays of neutral lipids (triglycerides) and dissimilar grades of inflammation in sebocytes.
Asunto(s)
Ácidos Grasos , Estearatos , Humanos , Ácidos Grasos/metabolismo , Estearatos/metabolismo , Glándulas Sebáceas/metabolismo , Citocinas/metabolismo , Palmitatos/metabolismo , Estearoil-CoA Desaturasa/metabolismo , Ácido Graso Desaturasas/metabolismoRESUMEN
Glucocorticoids (GCs) are commonly used in the treatment of inflammatory skin diseases, although the balance between therapeutic benefits and side effects is still crucial in clinical practice. One of the major and well-known adverse effects of topical GCs is cutaneous atrophy, which seems to be related to the activation of the glucorticoid receptor (GR) genomic pathway. Dissociating anti-inflammatory activity from atrophogenicity represents an important goal to achieve, in order to avoid side effects on keratinocytes and fibroblasts, known target cells of GC action. To this end, we evaluated the biological activity and safety profile of two novel chemical compounds, DE.303 and KL.202, developed as non-transcriptionally acting GR ligands. In primary keratinocytes, both compounds demonstrated anti-inflammatory properties inhibiting NF-κB activity, downregulating inflammatory cytokine release and interfering with pivotal signaling pathways involved in the inflammatory process. Of note, these beneficial actions were not associated with GC-related atrophic effects: treatments of primary keratinocytes and fibroblasts with DE.303 and KL.202 did not induce, contrarily to dexamethasone-a known potent GC-alterations in extracellular matrix components and lipid synthesis, thus confirming their safety profile. These data provide the basis for evaluating these compounds as effective alternatives to the currently used GCs in managing inflammatory skin diseases.
Asunto(s)
Dermatitis , Receptores de Glucocorticoides , Humanos , Piel , Antiinflamatorios/efectos adversos , Queratinocitos , Glucocorticoides/efectos adversos , Dermatitis/tratamiento farmacológico , Dermatitis/etiología , AtrofiaRESUMEN
The endocannabinoid system regulates physiological processes, and the modulation of endogenous endocannabinoid (eCB) levels is an attractive tool to contrast the development of pathological skin conditions including cancers. Inhibiting FAAH (fatty acid amide hydrolase), the degradation enzyme of the endocannabinoid anandamide (AEA) leads to the increase in AEA levels, thus enhancing its biological effects. Here, we evaluated the anticancer property of the FAAH inhibitor URB597, investigating its potential to counteract epithelial-to-mesenchymal transition (EMT), a process crucially involved in tumor progression. The effects of the compound were determined in primary human keratinocytes, ex vivo skin explants, and the squamous carcinoma cell line A431. Our results demonstrate that URB597 is able to hinder the EMT process by downregulating mesenchymal markers and reducing migratory potential. These effects are associated with the dampening of the AKT/STAT3 signal pathways and reduced release of pro-inflammatory cytokines and tumorigenic lipid species. The ability of URB597 to contrast the EMT process provides insight into effective approaches that may also include the use of FAAH inhibitors for the treatment of skin cancers.
Asunto(s)
Endocannabinoides , Neoplasias , Humanos , Endocannabinoides/farmacología , Endocannabinoides/metabolismo , Alcamidas Poliinsaturadas/farmacología , Alcamidas Poliinsaturadas/metabolismo , Amidohidrolasas/metabolismo , Queratinocitos/metabolismoRESUMEN
Bovine colostrum, the first milk secreted by the mammary glands of cows shortly after they have given birth, provides a natural source of bioactive substances helpful to promote tissue development and repair, and to maintain a healthy immune system. Owing to its properties, the use of colostrum in the treatment of human diseases is under investigation. We evaluated the biological activity of colostrum on human primary keratinocytes, focusing on its effects with regard to a proliferation/differentiation balance. Using cellular and molecular approaches, we showed that colostrum favors a cell cycle withdrawal by increasing the expression of p21/WAF1 and p27/KIP1. It also promotes the transition of keratinocytes from a proliferating to a differentiating state, as assessed by a decrease in keratin 5 and an increase in keratin 16. We demonstrated the ability of colostrum to induce the expression of early and late differentiation markers (keratin 1, involucrin, and filaggrin) and the synthesis of caspase 14 and bleomycin hydrolase, the two main enzymes involved in filaggrin maturation. Moreover, we showed that bovine colostrum is able to promote keratinocyte stratification and terminal differentiation not only in two-dimensional (2D), but also in a more physiological system of three-dimensional (3D) skin equivalents. Finally, we demonstrated that colostrum stimulates cell differentiation through the PI3K/PLC-γ1/PKCα pathways mainly associated to tyrosine kinase receptors. These results suggest the possibility to benefit from colostrum properties for the treatment of skin diseases characterized by altered differentiation and perturbed barrier function.
Asunto(s)
Diferenciación Celular , Calostro/metabolismo , Proteínas de Filamentos Intermediarios/metabolismo , Queratinocitos/citología , Piel/citología , Animales , Bovinos , Células Cultivadas , Femenino , Proteínas Filagrina , Humanos , Queratinocitos/metabolismo , Embarazo , Piel/metabolismoRESUMEN
The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor expressed in all skin cell types, plays a key role in physiological and pathological processes. Several studies have shown that this receptor is involved in the prevention of inflammatory skin diseases, e.g., psoriasis, atopic dermatitis, representing a potential therapeutic target. We tested the safety profile and the biological activity of NPD-0614-13 and NPD-0614-24, two new synthetic AhR ligands structurally related to the natural agonist FICZ, known to be effective in psoriasis. NPD-0614-13 and NPD-0614-24 did not alter per se the physiological functions of the different skin cell populations involved in the pathogenesis of inflammatory skin diseases. In human primary keratinocytes stimulated with tumor necrosis factor-α or lipopolysaccharide the compounds were able to counteract the altered proliferation and to dampen inflammatory signaling by reducing the activation of p38MAPK, c-Jun, NF-kBp65, and the release of cytokines. Furthermore, the molecules were tested for their beneficial effects in human epidermal and full-thickness reconstituted skin models of psoriasis. NPD-0614-13 and NPD-0614-24 recovered the psoriasis skin phenotype exerting pro-differentiating activity and reducing the expression of pro-inflammatory cytokines and antimicrobial peptides. These data provide a rationale for considering NPD-0614-13 and NPD-0614-24 in the management of psoriasis.
Asunto(s)
Antiinflamatorios/farmacología , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Catecoles/farmacología , Diferenciación Celular , Inflamación/tratamiento farmacológico , Compuestos Organometálicos/farmacología , Psoriasis/tratamiento farmacológico , Receptores de Hidrocarburo de Aril/metabolismo , Piel/efectos de los fármacos , Humanos , Inflamación/metabolismo , Inflamación/patología , Queratinocitos/efectos de los fármacos , Queratinocitos/metabolismo , Queratinocitos/patología , Ligandos , Psoriasis/metabolismo , Psoriasis/patología , Piel/metabolismo , Piel/patologíaRESUMEN
Acne is the most common skin disease in adolescent Westernized populations. Several data support the involvement of the mammalian target of rapamycin complex 1 (mTORC1) signalling in the interplay between androgens, insulin, insulin-like growth factor (IGF1) and high-glycaemic index diet in acne. The peroxisome proliferator-activated receptor γ (PPARγ) is involved in both differentiation and anti-inflammatory response. Low differentiated sebocytes showed decreased expression of PPARγ and increased level of insulin and IGF-1 receptors, resulting in the production of acne-like sebum and inflammatory mediators. In this viewpoint, we discuss how in acne the dysregulation of proliferation and differentiation processes in sebocytes and keratinocytes may be associated with altered response to androgens and other hormones, such as insulin or IGF-1. Moreover, we propose PPARγ modulation as an innovative therapeutic approach to normalize sebocyte differentiation process, interfering with the different mechanisms involved in altered pilosebaceous unit.
Asunto(s)
Acné Vulgar/etiología , Diferenciación Celular , Hormonas/metabolismo , Acné Vulgar/metabolismo , Humanos , Factor I del Crecimiento Similar a la Insulina/metabolismo , Queratinocitos/metabolismo , PPAR gamma/metabolismoRESUMEN
Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor expressed in many tissues, including skin, where it is essential for maintaining skin barrier permeability, regulating cell proliferation/differentiation, and modulating antioxidant and inflammatory responses upon ligand binding. Therefore, PPARγ activation has important implications for skin homeostasis. Over the past 20 years, with increasing interest in the role of PPARs in skin physiopathology, considerable effort has been devoted to the development of PPARγ ligands as a therapeutic option for skin inflammatory disorders. In addition, PPARγ also regulates sebocyte differentiation and lipid production, making it a potential target for inflammatory sebaceous disorders such as acne. A large number of studies suggest that PPARγ also acts as a skin tumor suppressor in both melanoma and non-melanoma skin cancers, but its role in tumorigenesis remains controversial. In this review, we have summarized the current state of research into the role of PPARγ in skin health and disease and how this may provide a starting point for the development of more potent and selective PPARγ ligands with a low toxicity profile, thereby reducing unwanted side effects.
Asunto(s)
PPAR gamma , Piel , PPAR gamma/metabolismo , Humanos , Animales , Piel/metabolismo , Piel/patología , Neoplasias Cutáneas/metabolismo , Neoplasias Cutáneas/patología , Enfermedades de la Piel/metabolismo , Enfermedades de la Piel/patología , Ligandos , Diferenciación CelularRESUMEN
Derangement of the epidermal barrier lipids and dysregulated immune responses are key pathogenic features of atopic dermatitis (AD). The Th2-type cytokines interleukin IL-4 and IL-13 play a prominent role in AD by activating the Janus Kinase/Signal Transduction and Activator of Transcription (JAK/STAT) intracellular signaling axis. This study aimed to investigate the role of JAK/STAT in the lipid perturbations induced by Th2 signaling in 3D epidermal equivalents. Tofacitinib, a low-molecular-mass JAK inhibitor, was used to screen for JAK/STAT-mediated deregulation of lipid metabolism. Th2 cytokines decreased the expression of elongases 1, 3, and 4 and serine-palmitoyl-transferase and increased that of sphingolipid delta(4)-desaturase and carbonic anhydrase 2. Th2 cytokines inhibited the synthesis of palmitoleic acid and caused depletion of triglycerides, in association with altered phosphatidylcholine profiles and fatty acid (FA) metabolism. Overall, the ceramide profiles were minimally affected. Except for most sphingolipids and very-long-chain FAs, the effects of Th2 on lipid pathways were reversed by co-treatment with tofacitinib. An increase in the mRNA levels of CPT1A and ACAT1, reduced by tofacitinib, suggests that Th2 cytokines promote FA beta-oxidation. In conclusion, pharmacological inhibition of JAK/STAT activation prevents the lipid disruption caused by the halted homeostasis of FA metabolism.
Asunto(s)
Citocinas , Quinasas Janus , Metabolismo de los Lípidos , Factores de Transcripción STAT , Células Th2 , Humanos , Citocinas/metabolismo , Epidermis/metabolismo , Epidermis/efectos de los fármacos , Ácidos Grasos/metabolismo , Interleucina-4/metabolismo , Inhibidores de las Cinasas Janus/farmacología , Quinasas Janus/antagonistas & inhibidores , Quinasas Janus/metabolismo , Metabolismo de los Lípidos/efectos de los fármacos , Piperidinas/farmacología , Pirimidinas/farmacología , Transducción de Señal/efectos de los fármacos , Factores de Transcripción STAT/antagonistas & inhibidores , Factores de Transcripción STAT/metabolismo , Células Th2/metabolismo , Células Th2/efectos de los fármacos , Técnicas de Cultivo Tridimensional de CélulasRESUMEN
Azelaic acid (AzA) has been used for the treatment for inflammatory skin diseases, such as acne and rosacea. Interestingly, an improvement in skin texture has been observed after long-time treatment with AzA. We previously unrevealed that anti-inflammatory activity of AzA involves a specific activation of PPARγ, a nuclear receptor that plays a relevant role in inflammation and even in ageing processes. As rosacea has been considered as a photo-aggravated disease, we investigated the ability of AzA to counteract stress-induced premature cell senescence (SIPS). We employed a SIPS model based on single exposure of human dermal fibroblasts (HDFs) to UVA and 8-methoxypsoralen (PUVA), previously reported to activate a senescence-like phenotype, including long-term growth arrest, flattened morphology and increased synthesis of matrix metalloproteinases (MMPs) and senescence-associated ß-galactosidase (SA-ß-gal). We found that PUVA-treated HDFs grown in the presence of AzA maintained their morphology and reduced MMP-1 release and SA-ß-galactosidase-positive cells. Moreover, AzA induced a reduction in ROS generation, an up-modulation of antioxidant enzymes and a decrease in cell membrane lipid damages in PUVA-treated HDFs. Further evidences of AzA anti-senescence effect were repression of p53 and p21, increase in type I pro-collagen and abrogation of the enhanced expression of growth factors, such as HGF and SCF. Interestingly, PUVA-SIPS showed a decreased activation of PPARγ and AzA counteracted this effect, suggesting that AzA effect involves PPARγ modulation. All together these data showed that AzA interferes with PUVA-induced senescence-like phenotype and its ability to activate PPAR-γ provides relevant insights into the anti-senescence mechanism.
Asunto(s)
Senescencia Celular/efectos de los fármacos , Fármacos Dermatológicos/farmacología , Ácidos Dicarboxílicos/farmacología , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , PPAR gamma/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Células Cultivadas , Senescencia Celular/efectos de la radiación , Colágeno Tipo I/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Fibroblastos/citología , Factor de Crecimiento de Hepatocito/metabolismo , Humanos , Metaloproteinasa 1 de la Matriz/metabolismo , Metoxaleno/farmacología , Terapia PUVA , Fenotipo , Fosfolípidos/metabolismo , Fármacos Fotosensibilizantes/farmacología , Procolágeno/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Factor de Células Madre/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Rayos Ultravioleta , beta-Galactosidasa/metabolismoRESUMEN
Cystinosis is a rare autosomal recessive disease characterized by cystine crystal accumulation leading to multiorgan dysfunctions and caused by mutation in CTNS. CTNS encodes cystinosin, a cystine/H(+) symporter that exports cystine out of the lysosomes. Patients with cystinosis frequently exhibit blond hair and fair complexion, suggesting an alteration in melanogenesis. However, the pigmentation singularities of these patients have not been studied, and the role of cystinosin in melanogenesis has remained unknown. In our study, a clinical evaluation of 27 patients with cystinosis showed that 44% had a cutaneous pigmentation dilution compared to their relatives. Analysis of the hair melanin content in these patients by HPLC demonstrated a 50% decrease in eumelanin (4360 vs. 9360 ng/mg), and a 2-fold increase in pheomelanin (53 vs. 20 ng/mg), the yellow/red pigments. Cystinosin-deficient mice also showed a 4-fold increase in hair pheomelanin content. In vitro studies showed that cystinosin was located at melanosomes. CTNS silencing led to a 75% reduction of melanin synthesis that was caused by a degradation of tyrosinase by lysosomal proteases. Our results objectify the pigmentation defect in patients with cystinosis. We also identify the role of CTNS in melanogenesis and add a new gene to the list of the genes involved in the control of skin and hair pigmentation.
Asunto(s)
Sistemas de Transporte de Aminoácidos Neutros/fisiología , Melaninas/biosíntesis , Melanosomas/metabolismo , Adolescente , Adulto , Sistemas de Transporte de Aminoácidos Neutros/genética , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Animales , Línea Celular Tumoral , Niño , Preescolar , Cistinosis/metabolismo , Femenino , Humanos , Masculino , Ratones , Ratones Noqueados , Mutación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Pigmentación de la Piel/genética , Adulto JovenRESUMEN
Insulin affects metabolic processes in different organs, including the skin. The sebaceous gland (SG) is an important appendage in the skin, which responds to insulin-mediated signals, either directly or through the insulin growth factor 1 (IGF-1) axis. Insulin cues are differently translated into the activation of metabolic processes depending on several factors, including glucose levels, receptor sensitivity, and sebocyte differentiation. The effects of diet on both the physiological function and pathological conditions of the SG have been linked to pathways activated by insulin and IGF-1. Experimental evidence and theoretical speculations support the association of insulin resistance with acne vulgaris, which is a major disorder of the SG. In this review, we examined the effects of insulin on the SG function and their implications in the pathogenesis of acne.
RESUMEN
Stimulation of melanocytes and murine melanoma cells with αMSH plus the PI3K inhibitor LY294002 resulted in ROS increase, oxidative DNA damage, and pigment retention. We performed cellular and molecular biology assays (Western blot, FACS, immunofluorescence analysis, scratch assay) on murine and human melanoma cells. Treatment with αMSH plus LY294002 altered cortical actin architecture. Given that cytoskeleton integrity requires energy, we next evaluated ATP levels and we observed a drop in ATP after exposure to αMSH plus LY294002. To evaluate if the αMSH-activated PI3K pathway could modulate energy metabolism, we focused on glucose uptake by analyzing the expression of the Glut-1 glucose translocator. Compared with cells treated with αMSH alone, those exposed to combined treatment showed a reduction of Glut-1 on the plasma membrane. This metabolic alteration was associated with changes in mitochondrial mass. A significant decrease of the cell migratory potential was also observed. We demonstrated that the αMSH-dependent PI3K pathway acts as a regulator of energy metabolism via glucose uptake, influencing the actin cytoskeleton, which is involved in melanosome release and cell motility. Hence, these results could constitute the basis for innovative therapeutical strategies.
Asunto(s)
Melanoma , Fosfatidilinositol 3-Quinasas , Humanos , Animales , Ratones , Fosfatidilinositol 3-Quinasas/metabolismo , alfa-MSH/farmacología , Melanoma/metabolismo , Metabolismo Energético , Glucosa , Adenosina Trifosfato/metabolismoRESUMEN
Cutaneous squamous cell carcinoma (cSCC) is the most common UV-induced keratinocyte-derived cancer, and its progression is characterized by the epithelial-mesenchymal transition (EMT) process. We previously demonstrated that PPARγ activation by 2,4,6-octatrienoic acid (Octa) prevents cutaneous UV damage. We investigated the possible role of the PPARγ activators Octa and the new compound (2Z,4E,6E)-2-methoxyocta-2,4,6-trienoic acid (A02) in targeting keratinocyte-derived skin cancer. Like Octa, A02 exerted a protective effect against UVB-induced oxidative stress and DNA damage in NHKs. In the squamous cell carcinoma A431 cells, A02 inhibited cell proliferation and increased differentiation markers' expression. Moreover, Octa and even more A02 counteracted the TGF-ß1-dependent increase in mesenchymal markers, intracellular ROS, the activation of EMT-related signal transduction pathways, and cells' migratory capacity. Both compounds, especially A02, counterbalanced the TGF-ß1-induced cell membrane lipid remodeling and the release of bioactive lipids involved in EMT. In vivo experiments on a murine model useful to study cell proliferation in adult animals showed the reduction of areas characterized by active cell proliferation in response to A02 topical treatment. In conclusion, targeting PPARγ may be useful for the prevention and treatment of keratinocyte-derived skin cancer.
Asunto(s)
Carcinoma de Células Escamosas , Neoplasias Cutáneas , Ratones , Animales , Carcinoma de Células Escamosas/patología , Transición Epitelial-Mesenquimal , Factor de Crecimiento Transformador beta1/farmacología , PPAR gamma/metabolismo , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/metabolismo , CarcinogénesisRESUMEN
Melasma is a hyperpigmentary disorder with photoaging features, whose manifestations appear on specific face areas, rich in sebaceous glands (SGs). To explore the SGs possible contribution to the onset, the expression of pro-melanogenic and inflammatory factors from the SZ95 SG cell line exposed to single or repetitive ultraviolet (UVA) radiation was evaluated. UVA up-modulated the long-lasting production of α-MSH, EDN1, b-FGF, SCF, inflammatory cytokines and mediators. Irradiated SZ95 sebocyte conditioned media increased pigmentation in melanocytes and the expression of senescence markers, pro-inflammatory cytokines, and growth factors regulating melanogenesis in fibroblasts cultures. Cocultures experiments with skin explants confirmed the role of sebocytes on melanogenesis promotion. The analysis on sebum collected from melasma patients demonstrated that in vivo sebocytes from lesional areas express the UVA-activated pathways markers observed in vitro. Our results indicate sebocytes as one of the actors in melasma pathogenesis, inducing prolonged skin cell stimulation, contributing to localized dermal aging and hyperpigmentation.
RESUMEN
The synthesis of melanin pigments, or melanogenesis, is regulated by the balance of a variety of signal transduction pathways. Among these pathways, p38 MAPK signaling was found to be involved in stress-induced melanogenesis and to be activated by alpha-melanocyte-stimulating hormone (alpha-MSH) and ultraviolet irradiation. Previous studies have shown that alpha-MSH-stimulated melanogenesis can be inhibited by blocking p38 MAPK activity with SB203580, a pyridinyl imidazole compound. Consistent with this, we observed that pyridinyl imidazoles (SB203580 and SB202190) inhibited both basal and alpha-MSH-induced melanogenesis in B16 melanoma cells. However, SB202474, which has no ability to inhibit p38 MAPK activity and is usually used as a negative control compound in p38 MAPK studies, also suppressed melanin synthesis induction. Furthermore, the independence of the p38 kinase pathway from the repression of melanogenesis by pyridinyl imidazole compounds was also confirmed by small interfering RNA experiments. Interfering with p38 MAPK expression surprisingly stimulated melanogenesis and tyrosinase family protein expression. Although the molecular mechanism(s) by which p38 promotes the degradation of melanogenic enzymes remain to be determined, the involvement of the ubiquitin-proteasome pathway was demonstrated by co-treatment with the proteasome-specific inhibitor MG132 and the relative decrease in the ubiquitination of tyrosinase in cells transfected with p38-specific small interfering RNA.
Asunto(s)
Sistema de Señalización de MAP Quinasas/fisiología , Monofenol Monooxigenasa/metabolismo , Pigmentación/fisiología , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Animales , Inhibidores Enzimáticos/metabolismo , Estabilidad de Enzimas , Regulación de la Expresión Génica/efectos de la radiación , Humanos , Imidazoles/metabolismo , Melaninas/biosíntesis , Melaninas/genética , Melanoma Experimental/metabolismo , Ratones , Factor de Transcripción Asociado a Microftalmía/genética , Factor de Transcripción Asociado a Microftalmía/metabolismo , Monofenol Monooxigenasa/genética , Piridinas/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Ubiquitinadas/metabolismo , Rayos Ultravioleta , alfa-MSH/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Proteínas Quinasas p38 Activadas por Mitógenos/genéticaRESUMEN
The melanocortin-1 receptor (MC1R) belongs to the family of the G protein-coupled receptor (GPCR). Activated GPCRs can promote the phosphoinositide 3-kinase (PI3K) pathway. Few studies deal with the role of the PI3K pathway activation in response to αMSH. On B16-F10 cell line, we investigated the αMSH-dependent modulation of pAKT/AKT, as a key element of the PI3K pathway after rapid and prolonged stimulation. We demonstrated that αMSH triggers a rapid modulation of AKT which culminates in an increase in its phosphorylation. We highlighted a comparable upregulation of pAKT after exposure to αMSH on primary cultures of normal human melanocytes (NHMs) expressing a wild-type MC1R. On B16-F10 cells, NHMs, and an ex vivo model of human skin biopsies, we explored the influence of PI3K/AKT signaling triggered by αMSH, focusing on the control of melanogenesis and pigment release. We showed that the αMSH-dependent PI3K/AKT pathway exerts a negative feedback on melanogenesis and promotes the extracellular release of pigment. We strengthened the role of the PI3K/AKT pathway triggered by αMSH in preserving redox equilibrium and genome integrity, highlighting its role in affecting cell survival.
Asunto(s)
Retroalimentación Fisiológica , Melaninas/metabolismo , Melanocitos/citología , Melanoma Experimental/patología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , alfa-MSH/farmacología , Animales , Humanos , Melanocitos/efectos de los fármacos , Melanocitos/metabolismo , Melanoma Experimental/metabolismo , Ratones , Fosfatidilinositol 3-Quinasas/genética , Fosforilación , Pigmentación , Proteínas Proto-Oncogénicas c-akt/genéticaRESUMEN
Glycogen synthase kinase 3beta (GSK3beta) is implicated in many biological events, including embryonic development, cell differentiation, apoptosis, and the insulin response. GSK3beta also plays a key role in the Wnt/beta-catenin pathway. The master regulator of the pigmentation microphthalmia-associated transcription factor (MITF) is a target for the Wnt pathway, however, to date, the regulatory role of GSK3beta in the control of melanogenesis has not been elucidated. In this study, we evaluated the effect of inhibiting GSK3beta activity on the regulation of melanocyte differentiation. Exposure of the murine melanoma cell line B16 and normal human melanocytes to GSK3beta specific inhibitors (SB216763, SB415286, BIO, and LiCl) resulted in a dose-dependent accumulation of beta-catenin. This is associated with the induction of melanocyte differentiation-associated markers such as melanin synthesis, tyrosinase activity, and expression of tyrosinase and the microphthalmia-associated transcription factor. Attenuation of GSK3beta activity has an inhibitory effect on cell growth, and this was accompanied by morphological changes. Moreover, treatment of B16 cells with a siRNA targeted against beta-catenin completely abolished the promelanogenic effect of GSK3beta inhibition, however, the overexpression of a constitutively active mutant form of beta-catenin (pCS2beta-cat-mut) only slightly increased the degree of pigmentation. These results demonstrated that GSK3beta is implicated in the regulation of melanogenesis and that pharmacological inhibition of its activity could increase melanin synthesis through mechanisms probably not restricted to Wnt/beta-catenin pathway activation.
Asunto(s)
Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Melaninas/biosíntesis , Melanocitos/enzimología , Melanoma Experimental/enzimología , Animales , Diferenciación Celular/efectos de los fármacos , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Técnica del Anticuerpo Fluorescente , Glucógeno Sintasa Quinasa 3 beta , Humanos , Melanocitos/citología , Melanocitos/efectos de los fármacos , Ratones , Factor de Transcripción Asociado a Microftalmía/metabolismo , Monofenol Monooxigenasa/metabolismo , Pigmentación/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Transporte de Proteínas/efectos de los fármacos , ARN Interferente Pequeño/metabolismo , Regulación hacia Arriba/efectos de los fármacos , beta Catenina/metabolismoRESUMEN
Exposure of human fibroblasts to 8-methoxypsoralen plus ultraviolet-A irradiation (PUVA) results in stress-induced cellular senescence in fibroblasts. We here studied the role of the antioxidant defense system in the accumulation of reactive oxygen species (ROS) and the effect of the antioxidants alpha-tocopherol, N-acetylcysteine, and alpha-lipoic acid on PUVA-induced cellular senescence. PUVA treatment induced an immediate and increasing generation of intracellular ROS. Supplementation of PUVA-treated fibroblasts with alpha-tocopherol (alpha-Toc), N-acetylcysteine (NAC), or alpha-lipoic acid (alpha-LA) abrogated the increased ROS generation and rescued fibroblasts from the ROS-dependent changes into the cellular senescence phenotype, such as cytoplasmic enlargement, enhanced expression of senescence-associated-beta-galactosidase and matrix-metalloproteinase-1, hallmarks of photoaging and intrinsic aging. PUVA treatment disrupted the integrity of cellular membranes and impaired homeostasis and function of the cellular antioxidant system with a significant decrease in glutathione and hydrogen peroxide-detoxifying enzymes activities. Supplementation with NAC, alpha-LA, and alpha-Toc counteracted these changes. Our data provide causal evidence that (i) oxidative stress due to an imbalance in the overall cellular antioxidant capacity contributes to the induction and maintenance of the PUVA-induced fibroblast senescence and that (ii) low molecular antioxidants protect effectively against these deleterious alterations.
Asunto(s)
Antioxidantes/farmacología , Senescencia Celular/efectos de los fármacos , Senescencia Celular/efectos de la radiación , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/efectos de la radiación , Células Cultivadas , Niño , Preescolar , Fibroblastos , Glutatión/metabolismo , Humanos , Masculino , Fenotipo , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Increasing attention is addressed to identify products able to enhance skin photoprotection and to prevent skin carcinogenesis. Several studies have demonstrated that the α-melanocyte stimulating hormone (αMSH), acting on a functional MC1R, provides a photoprotective effect by inducing pigmentation, antioxidants and DNA repair. We discovered a link between αMSH and the nuclear receptor Peroxisome Proliferator-Activated Receptor-γ (PPARγ), suggesting that some of the αMSH protective effects may be dependent on PPARγ transcriptional activity. Moreover, we demonstrated that the activation of PPARγ by the parrodiene 2,4,6-octatrienoic acid (Octa) induces melanogenesis and antioxidant defence in human melanocytes and counteracts senescence-like phenotype in human fibroblasts. In this study, we demonstrate that the activation of PPARγ by Octa exerts a protective effect against UVA- and UVB-induced damage on normal human keratinocytes (NHKs), the major target cells of UV radiation. Octa promotes the antioxidant defence, augments DNA repair and reduces the induction of proteins involved in UV-induced DNA damage response. Our results contribute to deepen the analysis of the αMSH/PPARγ connection and suggest perspectives for the development of new molecules and formulations able to prevent cutaneous UV damage by acting on the different skin cell populations through PPARγ activation.
Asunto(s)
Ácidos Grasos Insaturados/farmacología , Queratinocitos/efectos de los fármacos , Queratinocitos/enzimología , Queratinocitos/efectos de la radiación , PPAR gamma/agonistas , Protectores contra Radiación/farmacología , Rayos Ultravioleta/efectos adversos , Antioxidantes/metabolismo , Células Cultivadas , Daño del ADN/efectos de los fármacos , Daño del ADN/efectos de la radiación , Activación Enzimática/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Queratinocitos/patología , PPAR gamma/genética , PPAR gamma/metabolismo , Receptor de Melanocortina Tipo 1/genética , Receptor de Melanocortina Tipo 1/metabolismo , alfa-MSH/metabolismoRESUMEN
BACKGROUND: The α-Melanocyte Stimulating Hormone (αMSH)/Melanocortin-1 receptor (MC1R) interaction promotes melanogenesis through the cAMP/PKA pathway. The direct induction of this pathway by Forskolin (FSK) is also known to enhance melanocyte proliferation. αMSH acts as a mitogenic agent in melanocytes and its effect on proliferation of melanoma cells is less known. We previously identified the αMSH/Peroxisome Proliferator Activated Receptor (PPARγ) pathway as a new pathway on the B16-F10 mouse melanoma cell line. αMSH induced the translocation of PPARγ into the nucleus as an active transcription factor. This effect was independent of the cAMP/PKA pathway and was mediated by the activation of the PI(4,5)P2/PLC pathway, a pathway which we have described to be triggered by the αMSH-dependent MC1R stimulation. Moreover, in the same study, preliminary experiments showed that mouse melanoma cells responded to αMSH by reducing proliferation and that PPARγ was involved in this effect. Due to its key role in the control of cell proliferation, PPARγ agonists are used in therapeutic models for different forms of cancer, including melanoma. The purpose of this study was: (a) to confirm the different proliferative behavior in response to αMSH in healthy and in melanoma condition; (b) to verify whether the cAMP/PKA pathway and the PLC/PPARγ pathway could exert an antagonistic function in the control of proliferation; (c) to deepen the knowledge of the molecular basis responsible for the down-proliferative response of melanoma cells after exposure to αMSH. METHODS: We employed B16-F10 cell line, a human melanoma cell line (Mel 13) and two primary cultures of human melanocytes (NHM 1 and NHM 2, respectively), all expressing a wild type MC1R and responding to the αMSH in terms of pigmentation. We evaluated cell proliferation through: a) cell counting, b) cell cycle analysis c) protein expression of proliferation modulators (p27, p21, cyclin D1 and cyclin E). RESULTS: The αMSH acted as a mitogenic agent in primary cultures of human melanocytes, whereas it determined a slow down of proliferation in melanoma cell lines. FSK, as an inducer of the cAMP/PKA pathway, reproduced the αMSH mediated effect on proliferation in NHMs but it did not mimic the αMSH effect on proliferation in B16-F10 and Mel 13 melanoma cell lines. Meanwhile, 3 M3-FBS (3 M3), as an inducer of PI(4,5)P2/PLC pathway, reproduced the αMSH proliferative effect. Further experiments, treating melanoma cell lines with αMSH in the presence/absence of GW9662, as an inhibitor of PPARγ, confirmed the key role of this transcription factor in decreasing cell proliferation in response to the hormone exposure. CONCLUSIONS: In both melanoma cell lines, αMSH determined the reduction of proliferation through the PI(4,5)P2/PLC pathway, employing PPARγ as an effector element. These evidence could offer perspectives for new therapeutic approaches for melanoma.