RESUMO
The melanocortin 1 receptor (MC1R), which signals through cAMP, is a melanocytic transmembrane receptor involved in pigmentation, adaptive tanning, and melanoma resistance. We report MC1R-mediated or pharmacologically-induced cAMP signaling promotes nucleotide excision repair (NER) in a cAMP-dependent protein kinase A (PKA)-dependent manner. PKA directly phosphorylates ataxia telangiectasia and Rad3-related protein (ATR) at Ser435, which actively recruits the key NER protein xeroderma pigmentosum complementation group A (XPA) to sites of nuclear UV photodamage, accelerating clearance of UV-induced photolesions and reducing mutagenesis. Loss of Ser435 within ATR prevents PKA-mediated ATR phosphorylation, disrupts ATR-XPA binding, delays recruitment of XPA to UV-damaged DNA, and elevates UV-induced mutagenesis. This study mechanistically links cAMP-PKA signaling to NER and illustrates potential benefits of cAMP pharmacological rescue to reduce UV mutagenesis in MC1R-defective, melanoma-susceptible individuals.
Assuntos
Dano ao DNA , Receptor Tipo 1 de Melanocortina/genética , Proteína de Xeroderma Pigmentoso Grupo A/metabolismo , Animais , Proteínas Mutadas de Ataxia Telangiectasia/química , Proteínas Mutadas de Ataxia Telangiectasia/genética , Linhagem Celular Tumoral , Proteínas Quinases Dependentes de AMP Cíclico/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Células HEK293 , Humanos , Células MCF-7 , Camundongos , Camundongos Endogâmicos C57BL , Mutagênese/efeitos da radiação , Fosforilação/efeitos da radiação , Pigmentação/genética , Processamento de Proteína Pós-Traducional/genética , Processamento de Proteína Pós-Traducional/efeitos da radiação , Interferência de RNA , RNA Interferente Pequeno , Transdução de Sinais/genética , Transdução de Sinais/efeitos da radiação , Raios Ultravioleta , Proteína de Xeroderma Pigmentoso Grupo A/genéticaRESUMO
Blunted melanocortin 1 receptor (MC1R) signaling promotes melanocyte genomic instability in part by attenuating cAMP-mediated DNA repair responses, particularly nucleotide excision repair (NER), which recognizes and clears mutagenic photodamage. cAMP-enhanced NER is mediated by interactions between the ataxia telangiectasia-mutated and Rad3-related (ATR) and xeroderma pigmentosum complementation group A (XPA) proteins. We now report a critical role for sirtuin 1 (SIRT1) in regulating ATR-mediated phosphorylation of XPA. SIRT1 deacetylates XPA at residues Lys-63, Lys-67, and Lys-215 to promote interactions with ATR. Mutant XPA containing acetylation mimetics at residues Lys-63, Lys-67, and Lys-215 exhibit blunted UV-dependent ATR-XPA interactions even in the presence of cAMP signals. ATR-mediated phosphorylation of XPA on Ser-196 enhances cAMP-mediated optimization of NER and is promoted by SIRT1-mediated deacetylation of XPA on Lys-63, Lys-67, and Lys-215. Interference with ATR-mediated XPA phosphorylation at Ser-196 by persistent acetylation of XPA at Lys-63, Lys-67, and Lys-215 delays repair of UV-induced DNA damage and attenuates cAMP-enhanced NER. Our study identifies a regulatory ATR-SIRT1-XPA axis in cAMP-mediated regulation melanocyte genomic stability, involving SIRT1-mediated deacetylation (Lys-63, Lys-67, and Lys-215) and ATR-dependent phosphorylation (Ser-196) post-translational modifications of the core NER factor XPA.
Assuntos
Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Reparo do DNA/fisiologia , Sirtuína 1/metabolismo , Proteína de Xeroderma Pigmentoso Grupo A/metabolismo , Acetilação , Linhagem Celular Tumoral , AMP Cíclico/metabolismo , Humanos , Lisina/química , Melanócitos/efeitos da radiação , Fosforilação , Processamento de Proteína Pós-Traducional , Serina/química , Raios Ultravioleta , Proteína de Xeroderma Pigmentoso Grupo A/químicaRESUMO
People with pale skin, red hair, freckles and an inability to tan--the 'red hair/fair skin' phenotype--are at highest risk of developing melanoma, compared to all other pigmentation types. Genetically, this phenotype is frequently the product of inactivating polymorphisms in the melanocortin 1 receptor (MC1R) gene. MC1R encodes a cyclic AMP-stimulating G-protein-coupled receptor that controls pigment production. Minimal receptor activity, as in red hair/fair skin polymorphisms, produces the red/yellow pheomelanin pigment, whereas increasing MC1R activity stimulates the production of black/brown eumelanin. Pheomelanin has weak shielding capacity against ultraviolet radiation relative to eumelanin, and has been shown to amplify ultraviolet-A-induced reactive oxygen species. Several observations, however, complicate the assumption that melanoma risk is completely ultraviolet-radiation-dependent. For example, unlike non-melanoma skin cancers, melanoma is not restricted to sun-exposed skin and ultraviolet radiation signature mutations are infrequently oncogenic drivers. Although linkage of melanoma risk to ultraviolet radiation exposure is beyond doubt, ultraviolet-radiation-independent events are likely to have a significant role. Here we introduce a conditional, melanocyte-targeted allele of the most common melanoma oncoprotein, BRAF(V600E), into mice carrying an inactivating mutation in the Mc1r gene (these mice have a phenotype analogous to red hair/fair skin humans). We observed a high incidence of invasive melanomas without providing additional gene aberrations or ultraviolet radiation exposure. To investigate the mechanism of ultraviolet-radiation-independent carcinogenesis, we introduced an albino allele, which ablates all pigment production on the Mc1r(e/e) background. Selective absence of pheomelanin synthesis was protective against melanoma development. In addition, normal Mc1r(e/e) mouse skin was found to have significantly greater oxidative DNA and lipid damage than albino-Mc1r(e/e) mouse skin. These data suggest that the pheomelanin pigment pathway produces ultraviolet-radiation-independent carcinogenic contributions to melanomagenesis by a mechanism of oxidative damage. Although protection from ultraviolet radiation remains important, additional strategies may be required for optimal melanoma prevention.
Assuntos
Cor de Cabelo/genética , Melanoma/genética , Pigmentação da Pele/genética , Raios Ultravioleta , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Indóis/farmacologia , Melaninas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Monofenol Mono-Oxigenase/genética , Peroxidases/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas B-raf/genética , Receptor Tipo 1 de Melanocortina/genética , Sulfonamidas/farmacologia , Análise de Sobrevida , Células Tumorais CultivadasRESUMO
Loss-of-function in melanocortin 1 receptor (MC1R), a GS protein-coupled receptor that regulates signal transduction through cAMP and protein kinase A (PKA) in melanocytes, is a major inherited melanoma risk factor. Herein, we report a novel cAMP-mediated response for sensing and responding to UV-induced DNA damage regulated by A-kinase-anchoring protein 12 (AKAP12). AKAP12 is identified as a necessary participant in PKA-mediated phosphorylation of ataxia telangiectasia mutated and Rad3-related (ATR) at S435, a post-translational event required for cAMP-enhanced nucleotide excision repair (NER). Moreover, UV exposure promotes ATR-directed phosphorylation of AKAP12 at S732, which promotes nuclear translocation of AKAP12-ATR-pS435. This complex subsequently recruits XPA to UV DNA damage and enhances 5' strand incision. Preventing AKAP12's interaction with PKA or with ATR abrogates ATR-pS435 accumulation, delays recruitment of XPA to UV-damaged DNA, impairs NER and increases UV-induced mutagenesis. Our results define a critical role for AKAP12 as an UV-inducible scaffold for PKA-mediated ATR phosphorylation, and identify a repair complex consisting of AKAP12-ATR-pS435-XPA at photodamage, which is essential for cAMP-enhanced NER.
Assuntos
Proteínas de Ancoragem à Quinase A/fisiologia , Proteínas de Ciclo Celular/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/fisiologia , Processamento de Proteína Pós-Traducional , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Dano ao DNA , Reparo do DNA , Células HEK293 , Humanos , Cinética , Mutagênese , Fosforilação , Transporte Proteico , Proteína de Xeroderma Pigmentoso Grupo A/metabolismoRESUMO
Loss-of-function melanocortin 1 receptor (MC1R) polymorphisms are common in UV-sensitive fair-skinned individuals and are associated with blunted cAMP second messenger signalling and higher lifetime risk of melanoma because of diminished ability of melanocytes to cope with UV damage. cAMP signalling positions melanocytes to resist UV injury by upregulating synthesis of UV-blocking eumelanin pigment and by enhancing the repair of UV-induced DNA damage. cAMP enhances melanocyte nucleotide excision repair (NER), the genome maintenance pathway responsible for the removal of mutagenic UV photolesions, through cAMP-activated protein kinase (protein kinase A)-mediated phosphorylation of the ataxia telangiectasia-mutated and Rad3-related (ATR) protein on the S435 residue. We investigated the interdependence of cAMP-mediated melanin upregulation and cAMP-enhanced DNA repair in primary human melanocytes and a melanoma cell line. We observed that the ATR-dependent molecular pathway linking cAMP signalling to the NER pathway is independent of MITF activation. Similarly, cAMP-mediated upregulation of pigment synthesis is independent of ATR, suggesting that the key molecular events driving MC1R-mediated enhancement of genome maintenance (eg PKA-mediated phosphorylation of ATR) and MC1R-induced pigment induction (eg MITF activation) are distinct.
Assuntos
AMP Cíclico/metabolismo , Reparo do DNA , Melanócitos/citologia , Receptor Tipo 1 de Melanocortina/metabolismo , Pigmentação da Pele , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Linhagem Celular Tumoral , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Dano ao DNA , Humanos , Levodopa/química , Melaninas/química , Mutagênese , Nucleotídeos/química , Fosforilação , RNA Interferente Pequeno/metabolismo , Receptor Tipo 1 de Melanocortina/genética , Serina/química , Serina/genética , Transdução de Sinais , Raios Ultravioleta , Regulação para CimaRESUMO
The VTE is mainly a disease of the older adult, though its incidence has increased significantly in the pediatric population over the past several years. This trend is likely due to enhanced awareness and recognition of VTE, as well as increased prevalence of thromboembolic associated risk factors, such as increases in the proportion of children with predisposing medical conditions. The evaluation and management of a child with VTE is similar to that of adults, however pediatric patients have their own distinct aspects of care, stemming from particularities of the hemostatic system, age-related risk factors and differences in response to anticoagulant and antithrombotic therapy. This review addresses the risk factors and the evaluation and management of children with VTE.
Assuntos
Anticoagulantes/uso terapêutico , Fibrinolíticos/uso terapêutico , Trombectomia , Tromboembolia/terapia , Trombose Venosa/terapia , Adolescente , Doenças Autoimunes/complicações , Doenças Autoimunes/diagnóstico , Doenças Autoimunes/patologia , Cateteres Venosos Centrais/efeitos adversos , Criança , Cardiopatias Congênitas/complicações , Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/patologia , Humanos , Neoplasias/complicações , Neoplasias/diagnóstico , Neoplasias/patologia , Fatores de Risco , Sepse/complicações , Sepse/diagnóstico , Sepse/patologia , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Tromboembolia/diagnóstico , Tromboembolia/etiologia , Tromboembolia/cirurgia , Trombose Venosa/diagnóstico , Trombose Venosa/etiologia , Trombose Venosa/cirurgiaRESUMO
Being the largest and most visible organ of the body and heavily influenced by environmental factors, skin is ideal to study the long-term effects of aging. Throughout our lifetime, we accumulate damage generated by UV radiation. UV causes inflammation, immune changes, physical changes, impaired wound healing and DNA damage that promotes cellular senescence and carcinogenesis. Melanoma is the deadliest form of skin cancer and among the malignancies of highest increasing incidence over the last several decades. Melanoma incidence is directly related to age, with highest rates in individuals over the age of 55 years, making it a clear age-related disease. In this review, we will focus on UV-induced carcinogenesis and photo aging along with natural protective mechanisms that reduce amount of "realized" solar radiation dose and UV-induced injury. We will focus on the theoretical use of forskolin, a plant-derived pharmacologically active compound to protect the skin against UV injury and prevent aging symptoms by up-regulating melanin production. We will discuss its use as a topically-applied root-derived formulation of the Plectranthus barbatus (Coleus forskolii) plant that grows naturally in Asia and that has long been used in various Aryuvedic teas and therapeutic preparations.
Assuntos
AMP Cíclico/metabolismo , Melanoma/tratamento farmacológico , Extratos Vegetais/administração & dosagem , Neoplasias Cutâneas/tratamento farmacológico , Pele/patologia , Administração Tópica , Envelhecimento/efeitos dos fármacos , Envelhecimento/patologia , Envelhecimento/efeitos da radiação , Dano ao DNA/efeitos da radiação , Humanos , Melanoma/metabolismo , Melanoma/patologia , Pessoa de Meia-Idade , Extratos Vegetais/química , Plectranthus/química , Pele/efeitos da radiação , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Raios UltravioletaRESUMO
A team conducted semistructured interviews and developed case reports about financial toxicity (FT) and healthcare transitions (HCTs) with two adolescent and young adult (AYA) cancer survivors. These reports found poor HCTs f.
Assuntos
Sobreviventes de Câncer , Neoplasias , Transição para Assistência do Adulto , Humanos , Adolescente , Adulto Jovem , Estresse Financeiro , Atenção à Saúde , Neoplasias/terapiaRESUMO
Primary immune thrombocytopenia (ITP) is one of the most common bleeding disorders of childhood. In most cases, it presents with sudden widespread bruising and petechiae in an otherwise well child. Thought to be mainly a disorder of antibody-mediated platelet destruction, ITP can be self-limited or develop into a chronic condition. In this review, we discuss current concepts of the pathophysiology and treatment approaches to pediatric ITP.
Assuntos
Púrpura Trombocitopênica Idiopática/fisiopatologia , Púrpura Trombocitopênica Idiopática/terapia , Criança , HumanosRESUMO
Melanin is a free-radical scavenger, antioxidant, and broadband absorber of ultraviolet (UV) radiation which protects the skin from environmental carcinogenesis. However, melanin synthesis and UV-induced reactive melanin species are also implicated in melanocyte genotoxicity. Here, we attempted to reconcile these disparate functions of melanin using a UVB-sensitive, NRAS-mutant mouse model, TpN. We crossed TpN mice heterozygous for an inactivating mutation in Tyrosinase to produce albino and black littermates on a C57BL/6J background. These animals were then exposed to a single UVB dose on postnatal day three when keratinocytes in the skin have yet to be melanized. Approximately one-third (35%) of black mice were protected from UVB-accelerated tumor formation. However, melanoma growth rates, tumor mutational burdens, and gene expression profiles were similar in melanomas from black and albino mice. Skin from albino mice contained more cyclobutane pyrimidine dimer (CPD) positive cells than black mice 1-h post-irradiation. However, this trend gradually reversed over time with CPDs becoming more prominent in black than albino melanocytes at 48 h. These results show that in the absence of epidermal pigmentation, melanocytic melanin limits the tumorigenic effects of acute UV exposure but fails to protect melanocytes from UVB-induced mutagenesis.
Assuntos
Melanoma , Neoplasias Cutâneas , Camundongos , Animais , Melaninas/metabolismo , Neoplasias Cutâneas/patologia , Camundongos Endogâmicos C57BL , Melanócitos/metabolismo , Melanoma/patologia , Raios Ultravioleta , MutagêneseRESUMO
Ultraviolet-light (UV)-induced tanning is defective in numerous 'fair-skinned' individuals, many of whom contain functional disruption of the melanocortin 1 receptor (MC1R). Although this suggested a critical role for the MC1R ligand melanocyte stimulating hormone (MSH) in this response, a genetically controlled system has been lacking in which to determine the precise role of MSH-MC1R. Here we show that ultraviolet light potently induces expression of MSH in keratinocytes, but fails to stimulate pigmentation in the absence of functional MC1R in red/blonde-haired Mc1r(e/e) mice. However, pigmentation could be rescued by topical application of the cyclic AMP agonist forskolin, without the need for ultraviolet light, demonstrating that the pigmentation machinery is available despite the absence of functional MC1R. This chemically induced pigmentation was protective against ultraviolet-light-induced cutaneous DNA damage and tumorigenesis when tested in the cancer-prone, xeroderma-pigmentosum-complementation-group-C-deficient genetic background. These data emphasize the essential role of intercellular MSH signalling in the tanning response, and suggest a clinical strategy for topical small-molecule manipulation of pigmentation.
Assuntos
Colforsina/administração & dosagem , Colforsina/farmacologia , Receptor Tipo 1 de Melanocortina/metabolismo , Dermatopatias/prevenção & controle , Pigmentação da Pele/efeitos dos fármacos , Pigmentação da Pele/efeitos da radiação , Raios Ultravioleta , Administração Tópica , Animais , Melaninas/biossíntese , Hormônios Estimuladores de Melanócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Receptor Tipo 1 de Melanocortina/deficiência , Receptor Tipo 1 de Melanocortina/genética , Transdução de Sinais , Pele/efeitos dos fármacos , Pele/metabolismo , Pele/patologia , Pele/efeitos da radiação , Dermatopatias/etiologia , Dermatopatias/patologia , Pigmentação da Pele/fisiologiaRESUMO
Integrin α6ß4 is highly expressed in triple negative breast cancer (TNBC) and drives its most aggressive traits; however, its impact on chemotherapeutic efficacy remains untested. We found that integrin α6ß4 signaling promoted sensitivity to cisplatin and carboplatin but not to other chemotherapies tested. Mechanistic investigations revealed that integrin α6ß4 stimulated the activation of ATM, p53, and 53BP1, which required the integrin ß4 signaling domain. Genetic manipulation of gene expression demonstrated that mutant p53 cooperated with integrin α6ß4 for cisplatin sensitivity and was necessary for downstream phosphorylation of 53BP1 and enhanced ATM activation. Additionally, we found that in response to cisplatin-induced DNA double strand break (DSB), integrin α6ß4 suppressed the homologous recombination (HR) activity and enhanced non-homologous end joining (NHEJ) repair activity. Finally, we discovered that integrin α6ß4 preferentially activated DNA-PK, facilitated DNA-PK-p53 and p53-53BP1 complex formation in response to cisplatin and required DNA-PK to enhance ATM, 53BP1 and p53 activation as well as cisplatin sensitivity. In summary, we discovered a novel function of integrin α6ß4 in promoting cisplatin sensitivity in TNBC through DNA damage response pathway.
RESUMO
Skin complexion is among the most recognizable phenotypes between individuals and is mainly determined by the amount and type of melanin pigment deposited in the epidermis. Persons with dark skin complexion have more of a brown/black pigment known as eumelanin in their epidermis whereas those with fair skin complexions have less. Epidermal eumelanin acts as a natural sunblock by preventing incoming UV photons from penetrating into the skin and therefore protects against UV mutagenesis. By understanding the signaling pathways and regulation of pigmentation, strategies can be developed to manipulate skin pigmentation to improve UV resistance and to diminish skin cancer risk.
Assuntos
Preparações Farmacêuticas , Pigmentação da Pele/fisiologia , Animais , Inibidores Enzimáticos/farmacologia , Humanos , Melaninas/metabolismo , Pigmentação da Pele/efeitos dos fármacos , Pigmentação da Pele/genética , Pesquisa Translacional BiomédicaRESUMO
Ultraviolet (UV) radiation is a prime environmental stressor that our epidermis is exposed to on a daily basis. To avert UV-induced damage, epidermal stem cells (EpSCs) become pigmented via a process of heterotypic interaction between melanocytes and EpSCs; however, the molecular mechanisms of this interaction are not well understood. In this study, we show that the function of a key chromatin regulator, the Polycomb complex, was reduced upon UV exposure in human and mouse epidermis. Genetic ablation of key Polycomb subunits in murine EpSCs, mimicking depletion upon UV exposure, results in an increased number of epidermal melanocytes and subsequent epidermal pigmentation. Genome-wide transcriptional and chromatin studies show that Polycomb regulates the expression of UV-responsive genes and identifies type II collagen (COL2A1) as a critical secreted regulator of melanogenesis and epidermal pigmentation. Together, our findings show how UV exposure induces Polycomb-mediated changes in EpSCs to affect melanocyte behavior and promote epidermal pigmentation.
Assuntos
Células Epidérmicas/citologia , Epiderme/metabolismo , Melanócitos/metabolismo , Células-Tronco/citologia , Animais , Células Cultivadas , Epiderme/patologia , Queratinócitos/metabolismo , Camundongos Transgênicos , Pigmentação/fisiologia , Pigmentação da Pele/fisiologia , Raios Ultravioleta/efeitos adversosAssuntos
Endotelina-1/fisiologia , Melanócitos/efeitos da radiação , Tolerância a Radiação/fisiologia , Receptor de Endotelina B/fisiologia , Raios Ultravioleta/efeitos adversos , Apoptose/fisiologia , Apoptose/efeitos da radiação , Humanos , Melanócitos/patologia , Melanoma/patologia , Melanoma/fisiopatologia , Neoplasias Induzidas por Radiação/patologia , Neoplasias Induzidas por Radiação/fisiopatologia , Transdução de Sinais/fisiologia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/fisiopatologiaRESUMO
Geneticists estimate that 5% to 10% of all cancers diagnosed in the pediatric age range occur in children born with a genetic mutation that directly increases their lifetime risk for neoplasia. However, despite the fact that only a fraction of cancers in children occur as a result of an identified inherited predisposition, characterizing genetic mutations responsible for increased cancer risk in such syndromes has resulted in a profound understanding of relevant molecular pathways involved in carcinogenesis and/or resistance to neoplasia. Importantly, because most cancer predisposition syndromes result in an increased risk of a small number of defined malignancies, personalized prophylactic surveillance and preventive measures can be implemented in affected patients. Lastly, many of the same genetic targets identified from cancer-prone families are mechanistically involved in the majority of sporadic cancers in adults and children, thereby underscoring the clinical relevance of knowledge gained from these defined syndromes and introducing novel therapeutic opportunities to the broader oncologic community. This review highlights the clinical and genetic features of many of the known constitutional genetic syndromes that predispose to malignancy in children and young adults.
Assuntos
Predisposição Genética para Doença , Síndromes Neoplásicas Hereditárias/diagnóstico , Síndromes Neoplásicas Hereditárias/genética , Adulto , Criança , Humanos , Adulto JovemRESUMO
An in vitro skin diffusion study of pure forskolin (1) versus a 1-containing Plectranthus barbatus root extract (P. barbatus extract) in hairless guinea pig skin and human skin in a flow-through diffusion cell system was conducted and is being reported for the first time. Both topical agents were formulated in a solution of 70% ethanol and 30% propylene glycol (v/v). The results showed that forskolin can be delivered through the stratum corneum and that the flux of this compound was enhanced when 1 was delivered as a constituent of the P. barbatus extract as compared to an equivalent amount in pure form. These results suggest that the P. barbatus extract used contains permeation enhancement activity from other compound(s) contained in the crude root extract. It is possible that P. barbatus root extract may be used as an economical source of 1 to perform topical chemical manipulation of pigmentation in high-risk populations.