RESUMO
Phototoxicity and skin cancer are severe adverse effects of the anti-fungal drug Voriconazole (VOR). These adverse effects resemble those seen in xeroderma pigmentosum (XP), caused by defective DNA nucleotide excision repair (NER), and we show that VOR decreases NER capacity. We show that VOR treatment does not perturb the expression of NER, or other DNA damage-related genes, but that VOR localizes to heterochromatin, in complexes containing histone acetyltransferase GCN5. Impairment of GCN5 binding to histone H3 reduced acetylation of H3, restricting damage-dependent chromatin unfolding, thereby reducing NER initiation. Restoration of H3 histone acetylation using histone deacetylase inhibitors (HDACi), rescued VOR-induced NER repression, thus offering a preventive therapeutic option. These findings underline the importance of DNA damage-dependent chromatin remodeling as an important prerequisite of functional DNA repair.
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UVC222 nm has germicidal effects with potential clinical applications. However, UVC irradiation is capable of inducing DNA damage like cyclobutylpyrimidine dimers (CPD). Although new devices have emission peaks in the short-wavelength region of UVC (~222 nm), the remaining "collateral" radiation at longer wavelengths could be harmful to human health. We investigated the DNA damage caused by far-UVC 222 nm KrCl exciplex radiation on human skin reconstructs after additional filtering using silica filters. The skin reconstructs were irradiated with 100 mJ cm-2 , 500 mJ cm-2 , and 3 × 500 mJ cm-2 unfiltered and filtered (230-270 nm suppressed) far-UVC or UVB (308 nm) radiation. UVB and non-filtered UVC irradiation induced a significant amount of CPDs, compared with the background. Filtered far-UVC lowered the CPD amount compared with unfiltered UVC and UVB treatments. Repetitive UVC irradiation did not result in the accumulation of CPDs compared with UVB treatment. Reduction in excess of 99.9% of E. coli, S. aureus and C. albicans was detected after applying far-UVC radiation. This identifies a therapeutic window in which microorganisms are killed but tissue is still alive and not damaged, which could give rise to new clinical applications.
Assuntos
Escherichia coli , Staphylococcus aureus , Humanos , Dióxido de Silício , Pele/efeitos da radiação , Raios UltravioletaRESUMO
Ultraviolet (UV) radiation has a plethora of effects on human tissues. In the UV spectrum, wavelengths above 320 nm fall into the UVA range, and for these, it has been shown that they induce reactive oxygen species (ROS), DNA mutations and are capable to induce melanoma in mice. In addition to this, it was recently shown that UVA irradiation and UVA-induced ROS also increase glucose metabolism of melanoma cells. UVA irradiation causes a persistent increase in glucose consumption, accompanied by increased glycolysis, increased lactic acid production and activation of the pentose phosphate pathway. Furthermore, it was shown that the enhanced secretion of lactic acid is important for invasion of melanoma in vitro. The current knowledge of this link between UVA, metabolism and melanoma, possible mechanisms of UVA-induced glucose metabolism and their starting points are discussed in this review with focus on ROS- and UVA-induced cellular stress signalling, DNA damage signalling and DNA repair systems. When looking at the benefits of UVA-induced glucose metabolism, it becomes apparent that there are more advantages of these metabolic changes than one would expect. Besides the role of lactic acid as initiator of protease expression and invasion, its role for immune escape of melanoma cells and the pentose phosphate pathway-derived nicotinamide adenine dinucleotide phosphate (NADPH) as part of a ROS detoxification strategy are discussed.
Assuntos
Glucose/metabolismo , Melanoma/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Neoplasias Cutâneas/metabolismo , Pele/efeitos da radiação , Raios Ultravioleta/efeitos adversos , Animais , Sobrevivência Celular/efeitos da radiação , Dano ao DNA , Glicólise/efeitos da radiação , Humanos , Ácido Láctico/metabolismo , Melanoma/imunologia , Melanoma/patologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NADP/metabolismo , Invasividade Neoplásica , Via de Pentose Fosfato , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ácido Pirúvico/metabolismo , Pele/metabolismo , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/patologia , Evasão TumoralRESUMO
Melanoma is a malignant tumor in which UVA (320-400 nm) radiation is considered to be an important risk factor. But the role of UVA in melanoma progression toward an invasive phenotype is still not adequately investigated. For most proliferating tumor cells the preference of aerobic glycolysis has been described as the Warburg effect. Here we investigate the effect of UVA irradiation on changes in the Warburg effect and tumor progression toward invasive potential. On UVA irradiation, melanoma cell lines from initial tumors show an induction of the Warburg effect with increased glucose consumption and lactate production, which is at least partially mediated by reactive oxygen species. Associated with UVA treatment and enhanced lactic acid production, tumor-relevant proteases and in situ invasion is upregulated. Simultaneously, UVA increases intracellular concentrations of progression marker transketolase and activated protein kinase Akt, both involved in metabolic changes that increase with proliferation. Using invasion assays we show that lactic acid, resulting from the UVA enhanced and partially reactive oxygen species-mediated Warburg effect, increases the invasive potential of all melanoma cell lines investigated. Therefore, we demonstrate in melanoma cells that production of lactic acid, induced by UVA irradiation, increases invasiveness of melanoma cells via expression of tumor-relevant proteases.
Assuntos
Melanoma/patologia , Neoplasias Cutâneas/patologia , Raios Ultravioleta/efeitos adversos , Glicemia/análise , Linhagem Celular Tumoral/efeitos da radiação , Seguimentos , Humanos , Ácido Láctico/metabolismo , Melanoma/etiologia , Invasividade Neoplásica/patologia , Neoplasias Induzidas por Radiação/patologia , Doses de Radiação , Reação em Cadeia da Polimerase em Tempo Real/métodos , Medição de Risco , Neoplasias Cutâneas/etiologia , Melanoma Maligno CutâneoRESUMO
The genetic diagnosis in inherited optic neuropathies often remains challenging, and the emergence of complex neurological phenotypes that involve optic neuropathy is puzzling. Here we unravel two novel principles of genetic mechanisms in optic neuropathies: deep intronic OPA1 mutations, which explain the disease in several so far unsolved cases; and an intralocus OPA1 modifier, which explains the emergence of syndromic 'optic atrophy plus' phenotypes in several families. First, we unravelled a deep intronic mutation 364 base pairs 3' of exon 4b in OPA1 by in-depth investigation of a family with severe optic atrophy plus syndrome in which conventional OPA1 diagnostics including gene dosage analyses were normal. The mutation creates a new splice acceptor site resulting in aberrant OPA1 transcripts with retained intronic sequence and subsequent translational frameshift as shown by complementary DNA analysis. In patient fibroblasts we demonstrate nonsense mediated messenger RNA decay, reduced levels of OPA1 protein, and impairment of mitochondrial dynamics. Subsequent site-specific screening of >360 subjects with unexplained inherited optic neuropathy revealed three additional families carrying this deep intronic mutation and a base exchange four nucleotides upstream, respectively, thus confirming the clinical significance of this mutational mechanism. Second, in all severely affected patients of the index family, the deep intronic mutation occurred in compound heterozygous state with an exonic OPA1 missense variant (p.I382M; NM_015560.2). The variant alone did not cause a phenotype, even in homozygous state indicating that this long debated OPA1 variant is not pathogenic per se, but acts as a phenotypic modifier if it encounters in trans with an OPA1 mutation. Subsequent screening of whole exomes from >600 index patients identified a second family with severe optic atrophy plus syndrome due to compound heterozygous p.I382M, thus confirming this mechanism. In summary, we provide genetic and functional evidence that deep intronic mutations in OPA1 can cause optic atrophy and explain disease in a substantial share of families with unsolved inherited optic neuropathies. Moreover, we show that an OPA1 modifier variant explains the emergence of optic atrophy plus phenotypes if combined in trans with another OPA1 mutation. Both mutational mechanisms identified in this study-deep intronic mutations and intragenic modifiers-might represent more generalizable mechanisms that could be found also in a wide range of other neurodegenerative and optic neuropathy diseases.
Assuntos
GTP Fosfo-Hidrolases/genética , Genoma Humano/genética , Mutação/genética , Atrofia Óptica Autossômica Dominante/genética , Adolescente , Adulto , Idoso , Éxons/genética , Feminino , Dosagem de Genes/genética , Loci Gênicos/genética , Variação Genética , Humanos , Masculino , Pessoa de Meia-Idade , Atrofia Óptica Autossômica Dominante/classificação , Atrofia Óptica Autossômica Dominante/patologia , Linhagem , Fenótipo , SíndromeRESUMO
Cockayne syndrome (CS) is a rare autosomal recessive disease with progeroid symptoms, which is caused mainly by mutations in the CS genes CSA and CSB. Although the relevance of mitochondria in the aging process is known for several decades, research focused primarily on the role of the CS proteins in the nucleus. Recently, however, mitochondrial contribution to aging-associated symptoms of CS has been described. Inside mitochondria, CS proteins have roles, which partially differ from their nuclear functions. Up to now it is known that mitochondrial CS proteins are associated with base excision repair (BER) and transcription of mitochondrial DNA. However, it has been hypothesized that these are not the only functions of mitochondrial CS proteins as the occurrence of mutations like the common deletion are in need of separate explanations.
Assuntos
Envelhecimento/metabolismo , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/metabolismo , Reparo do DNA/genética , Proteínas Mitocondriais/metabolismo , Mutação , Fatores de Transcrição/metabolismo , Transcrição Gênica/genética , Envelhecimento/genética , Envelhecimento/patologia , Animais , Síndrome de Cockayne/genética , Síndrome de Cockayne/metabolismo , Síndrome de Cockayne/patologia , DNA Helicases/genética , Enzimas Reparadoras do DNA/genética , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Humanos , Proteínas Mitocondriais/genética , Proteínas de Ligação a Poli-ADP-Ribose , Fatores de Transcrição/genéticaRESUMO
The human genome is constantly exposed to various sources of DNA damage. Ineffective protection from this damage leads to genetic instability which can ultimately give rise to somatic disease, causing mutations. Therefore our organism commands a number of highly conserved and effective mechanisms responsible for DNA repair. If these repair mechanisms are defective due to germline mutations in relevant genes, rare diseases with DNA repair deficiencies can arise. Today, a limited number of rare hereditary diseases characterized by genetic defects of DNA repair mechanisms is known, comprising ataxia telangiectasia, Nijmegen breakage syndrome, Werner syndrome, Bloom Syndrome, Fanconi anemia, xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy. Although heterogeneous in respect to selected symptoms, these rare disorders share many clinical features such as growth retardation, neurological disorders, premature ageing, skin alterations including abnormal pigmentation, telangiectasia, xerosis cutis, pathological wound healing as well as an increased risk of developing different types of cancer. Based on the clinical similarities of symptoms as well as the predominant diagnostic technology available, many of these rare disorders were formerly classified as genodermatoses with cancer predisposition or chromosomal breakage symptoms. These pathological conditions not only severely impair patients with these rare genetic diseases but also represent symptoms affecting large parts of the general population.
Assuntos
Distúrbios no Reparo do DNA , Distúrbios no Reparo do DNA/diagnóstico , Distúrbios no Reparo do DNA/genética , Humanos , FenótipoRESUMO
Mutations of mitochondrial (mt) DNA, particularly the 4977 bp long common deletion, are increased in aging tissues and preferentially found in chronologically and photoaged skin. Mutations of human mitochondrial DNA (mtDNA) have also been identified in malignant tumors of the skin and of other organs. However, benign skin lesions have not yet been investigated. We analyzed the frequency of the common deletion in 27 benign skin lesions [8 seborrheic keratoses (SK), 5 epidermal nevi (EN), 14 solar lentigos (SL)] by quantitative real-time PCR, because SK and especially SL have been related to (photo)aged skin. All SK and four of five EN displayed reduced common deletion levels compared with adjacent normal skin. In contrast, 50% of SL revealed a higher percentage of the common deletion than the adjacent normal skin, and some SL showed very high absolute common deletion levels up to 14% of total mtDNA. Our results show that the amount of the common deletion is significantly different in benign skin lesions and raise further questions regarding the pathogenesis of SL and its possible role as a precursor lesion of SK.
Assuntos
DNA Mitocondrial/genética , Ceratose Seborreica/genética , Lentigo/genética , Deleção de Sequência/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Estudos de Casos e Controles , Criança , Feminino , Humanos , Lactente , Ceratose Seborreica/patologia , Lentigo/patologia , Masculino , Pessoa de Meia-Idade , Nevo Sebáceo de Jadassohn/genética , Nevo Sebáceo de Jadassohn/patologiaRESUMO
The free radical theory of aging postulates that the production of mitochondrial reactive oxygen species is the major determinant of aging and lifespan. Its role in aging of the connective tissue has not yet been established, even though the incidence of aging-related disorders in connective tissue-rich organs is high, causing major disability in the elderly. We have now addressed this question experimentally by creating mice with conditional deficiency of the mitochondrial manganese superoxide dismutase in fibroblasts and other mesenchyme-derived cells of connective tissues in all organs. Here, we have shown for the first time that the connective tissue-specific lack of superoxide anion detoxification in the mitochondria results in reduced lifespan and premature onset of aging-related phenotypes such as weight loss, skin atrophy, kyphosis (curvature of the spine), osteoporosis and muscle degeneration in mutant mice. Increase in p16(INK4a) , a robust in vivo marker for fibroblast aging, may contribute to the observed phenotype. This novel model is particularly suited to decipher the underlying mechanisms and to develop hopefully novel connective tissue-specific anti-aging strategies.
Assuntos
Envelhecimento/fisiologia , Tecido Conjuntivo/enzimologia , Longevidade/fisiologia , Mitocôndrias/enzimologia , Fenótipo , Superóxido Dismutase/deficiência , Animais , Biomarcadores/metabolismo , Osso e Ossos/patologia , Células Cultivadas , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Feminino , Fibroblastos/citologia , Fibroblastos/fisiologia , Humanos , Cifose , Masculino , Camundongos , Camundongos Knockout , Músculo Esquelético/patologia , Espécies Reativas de Oxigênio/metabolismo , Pele/patologia , Superóxido Dismutase/genética , Superóxidos/metabolismoRESUMO
BACKGROUND: Up to the 1950s, there was an ongoing debate about the diversity of hereditary optic neuropathies, in particular as to whether all inherited optic atrophies can be ascribed to Leber's hereditary optic neuropathy (LHON) or represent different disease entities. In 1954 W. Jaeger published a detailed clinical and genealogical investigation of a large family with explicit autosomal dominant segregation of optic atrophy thus proving the existence of a discrete disease different from LHON, which is nowadays known as autosomal dominant optic atrophy (ADOA). Since the year 2000 ADOA is associated with genomic mutations in the OPA1 gene, which codes for a protein that is imported into mitochondria where it is required for mitochondrial fusion. Interestingly enough, the underlying mutation in this family has not been identified since then. RESULTS: We have reinvestigated this family with the aim to identify the mutation and to further clarify the underlying pathomechanism. Patients showed a classical non-syndromic ADOA. The long term deterioration in vision in the two teenagers examined 50 years later is of particular note 5/20 to 6/120. Multiplex ligation probe amplification revealed a duplication of the OPA1 exons 7-9 which was confirmed by long distance PCR and cDNA analysis, resulting in an in-frame duplication of 102 amino acids. Segregation was verified in 53 available members of the updated pedigree and a penetrance of 88% was calculated. Fibroblast cultures from skin biopsies were established to assess the mitochondrial network integrity and to qualitatively and quantitatively study the consequences of the mutation on transcript and protein level. Fibroblast cultures demonstrated a fragmented mitochondrial network. Processing of the OPA1 protein was altered. There was no correlation of the OPA1 transcript levels and the OPA1 protein levels in the fibroblasts. Intriguingly an overall decrease of mitochondrial proteins was observed in patients' fibroblasts, while the OPA1 transcript levels were elevated. CONCLUSIONS: The thorough study of this family provides a detailed clinical picture accompanied by a molecular investigation of patients' fibroblasts. Our data show a classic OPA1-associated non-syndromic ADOA segregating in this family. Cell biological findings suggest that OPA1 is regulated by post-translational mechanisms and we would like to hypothesize that loss of OPA1 function might lead to impaired mitochondrial quality control. With the clinical, genetic and cell biological characterisation of a family described already more than 50 years ago, we span more than half a century of research in optic neuropathies.
RESUMO
Oral squamous cell carcinomas (OSCC) are frequent epithelial malignancies and afflicted with a poor prognosis. The majority of these cancers are treated with surgical resection and local recurrences are predominantly responsible for a fatal outcome. In order to provide a better understanding of the development of these local recurrences after surgical ablation, we developed an orthotopic floor-of-mouth squamous cell carcinoma murine model, in which local recurrences occur at a high frequency (55%, 8 out of 15 mice) within 6-21 days after microsurgical removal of the primary. Expression of the enhanced green fluorescent protein (eGFP) in the cancer cells allows in this new model to confirm complete surgical resection under the microscope and helps to track repopulating primary tumor cells in the local recurrence by optical imaging. In addition the model resembles all typical features of invasive head and neck cancers including the formation of lymph node metastasis and local infiltration.
Assuntos
Carcinoma de Células Escamosas/cirurgia , Modelos Animais de Doenças , Neoplasias Bucais/cirurgia , Recidiva Local de Neoplasia , Procedimentos Cirúrgicos Bucais , Animais , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/secundário , Linhagem Celular Tumoral , Feminino , Proteínas de Fluorescência Verde/biossíntese , Proteínas de Fluorescência Verde/genética , Metástase Linfática , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias Bucais/genética , Neoplasias Bucais/metabolismo , Neoplasias Bucais/patologia , Invasividade Neoplásica , Fatores de Tempo , Transfecção , Carga TumoralRESUMO
Defects in the DNA repair mechanism nucleotide excision repair (NER) may lead to tumors in xeroderma pigmentosum (XP) or to premature aging with loss of subcutaneous fat in Cockayne syndrome (CS). Mutations of mitochondrial (mt)DNA play a role in aging, but a link between the NER-associated CS proteins and base excision repair (BER)-associated proteins in mitochondrial aging remains enigmatic. We show functional increase of CSA and CSB inside mt and complex formation with mtDNA, mt human 8-oxoguanine glycosylase (mtOGG)-1, and mt single-stranded DNA binding protein (mtSSBP)-1 upon oxidative stress. MtDNA mutations are highly increased in cells from CS patients and in subcutaneous fat of aged Csb(m/m) and Csa(-/-) mice. Thus, the NER-proteins CSA and CSB localize to mt and directly interact with BER-associated human mitochondrial 8-oxoguanine glycosylase-1 to protect from aging- and stress-induced mtDNA mutations and apoptosis-mediated loss of subcutaneous fat, a hallmark of aging found in animal models, human progeroid syndromes like CS and in normal human aging.
Assuntos
Envelhecimento/genética , Síndrome de Cockayne/genética , Reparo do DNA , DNA Mitocondrial/genética , Gordura Subcutânea/metabolismo , Envelhecimento/metabolismo , Animais , Apoptose , Síndrome de Cockayne/metabolismo , Síndrome de Cockayne/fisiopatologia , DNA Glicosilases/metabolismo , DNA Helicases/genética , DNA Helicases/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a DNA , Humanos , Camundongos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Estresse Oxidativo , Proteínas de Ligação a Poli-ADP-Ribose , Ligação Proteica , Proteínas/genética , Proteínas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The role of ultraviolet radiation (UV) in the pathogenesis has been discussed controversially for many decades. Studies in mice (SCID, HGF/SF, SV40T) which develop malignant melanoma, show a role of UVB in melanomagenesis. In contrast to this, the role of UVA is less clear. We will review the recent in vitro and in vivo data in support of the hypothesis that UVA is also involved in the development of malignant melanoma. The role of UVA in p53 activation, apoptosis, cell cycle arrest and photoproduct formation is discussed.
Assuntos
Melanoma/etiologia , Neoplasias Cutâneas/etiologia , Raios Ultravioleta/efeitos adversos , Animais , Apoptose , Ciclo Celular , Dano ao DNA , Modelos Animais de Doenças , Humanos , Melanoma/metabolismo , Mitocôndrias/metabolismo , Estresse Oxidativo , Neoplasias Cutâneas/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
Progeroid syndromes are a group of diseases characterized by signs of premature aging. These syndromes comprise diseases such as Werner syndrome, Bloom syndrome, Rothmund-Thomson syndrome, Hutchinson-Gilford syndrome, Fanconi anemia, and ataxia-telangiectasia, as well as xeroderma pigmentosum, trichothiodystrophy, and Cockayne syndrome. Clinical symptoms of premature aging are skin atrophy with loss of cutaneous elasticity, dysfunction of cutaneous appendices, degeneration of the central nervous system and an increased susceptibility for malignant tumors. Genetic defects in the repair of DNA damage can lead to progeroid syndromes, and it is becoming increasingly evident that direct DNA damage and indirect damage by highly reactive oxygen species play central roles in aging. The clinical signs of progeroid syndromes and the molecular aspects of UV (ultraviolet radiation)-induced oxidative stress in aging are discussed.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 8-14; doi:10.1038/jidsymp.2009.6.
Assuntos
Síndrome de Cockayne/etiologia , Dano ao DNA , Raios Ultravioleta/efeitos adversos , Ataxia Telangiectasia/etiologia , Síndrome de Bloom/etiologia , Síndrome de Cockayne/genética , Síndrome de Cockayne/metabolismo , Reparo do DNA , Anemia de Fanconi/etiologia , Feminino , Humanos , Masculino , Modelos Biológicos , Estresse Oxidativo/efeitos da radiação , Progéria/etiologia , Síndrome de Rothmund-Thomson/etiologia , Síndromes de Tricotiodistrofia/etiologia , Síndrome de Werner/etiologia , Xeroderma Pigmentoso/etiologiaRESUMO
Excessive UVR ranks among the most harmful environmental influences on human skin. However, the direct impact of UVR on human skin appendages remains to be systematically investigated. Organ-cultured human anagen hair follicles in vitro were irradiated, and reduction of hair shaft elongation, premature catagen entry, and reduced hair matrix keratinocyte proliferation were observed upon irradiation with UVB (20/50 mJ cm(-2)). At 20 mJ cm(-2), apoptotic cell death prevailed (casp-3/p53 activation), whereas at 50 mJ cm(-2), necrotic cell death was predominant (lactate dehydrogenase increase). Mitochondrial common deletion and oxidatively damaged genomic DNA (8-OH-dG) was mainly observed at 20 mJ cm(-2). Follicular melanogenesis and ACTH immunoreactivity drastically declined, but alpha-melanocyte-stimulating hormone remained unchanged, whereas transforming growth factor-beta(2) expression shifted from the outer toward the inner root sheath. Both the number of Giemsa+ mast cells and the degree of mast-cell degranulation increased in the connective tissue sheath (CTS), and CD117 immunoreactivity of CTS cells and matrix keratinocytes was upregulated. Thus, UVR differentially modifies hair growth and cycle, promotes cell death, and induces complex regulatory events in human hair follicles in vitro. The leads from this human organ model, which is a living and human tissue interaction system under physiologically relevant in situ conditions, may encourage its use for general investigation of UV-induced effects as well as for testing possible agents for their UV-protective potency.
Assuntos
Folículo Piloso/patologia , Folículo Piloso/efeitos da radiação , Raios Ultravioleta/efeitos adversos , Hormônio Adrenocorticotrópico/metabolismo , Apoptose/efeitos da radiação , Degranulação Celular/efeitos da radiação , Diferenciação Celular/efeitos da radiação , Divisão Celular/efeitos da radiação , Fragmentação do DNA/efeitos da radiação , Relação Dose-Resposta à Radiação , Feminino , Cabelo/patologia , Cabelo/efeitos da radiação , Folículo Piloso/metabolismo , Humanos , Queratinócitos/patologia , Queratinócitos/efeitos da radiação , Mastócitos/patologia , Mastócitos/efeitos da radiação , Melaninas/biossíntese , Mitocôndrias/patologia , Mitocôndrias/efeitos da radiação , Técnicas de Cultura de Órgãos , Estresse Oxidativo/efeitos da radiação , Fator de Crescimento Transformador beta2/metabolismo , alfa-MSH/metabolismoRESUMO
Chemotherapy-induced alopecia represents one of the major unresolved problems of clinical oncology. The underlying molecular pathogenesis in humans is virtually unknown because of the lack of adequate research models. Therefore, we have explored whether microdissected, organ-cultured, human scalp hair follicles (HFs) in anagen VI can be exploited for dissecting and manipulating the impact of chemotherapy on human HFs. Here, we show that these organ-cultured HFs respond to a key cyclophosphamide metabolite, 4-hydroperoxycyclophosphamide (4-HC), in a manner that resembles chemotherapy-induced HF dystrophy as it occurs in vivo: namely, 4-HC induced melanin clumping and melanin incontinence, down-regulated keratinocyte proliferation, massively up-regulated apoptosis of hair matrix keratinocytes, prematurely induced catagen, and up-regulated p53. In addition, 4-HC induced DNA oxidation and the mitochondrial DNA common deletion. The organ culture system facilitated the identification of new molecular targets for chemotherapy-induced HF damage by microarray technology (eg, interleukin-8, fibroblast growth factor-18, and glypican 6). It was also used to explore candidate chemotherapy protectants, for which we used the cytoprotective cytokine keratinocyte growth factor as exemplary pilot agent. Thus, this novel system serves as a powerful yet pragmatic tool for dissecting and manipulating the impact of chemotherapy on the human HF.
Assuntos
Alopecia/induzido quimicamente , Alopecia/genética , Antineoplásicos/efeitos adversos , Folículo Piloso/efeitos dos fármacos , Técnicas de Cultura de Órgãos/métodos , Alopecia/patologia , Animais , Apoptose/genética , Bioensaio , Proliferação de Células/efeitos dos fármacos , Meios de Cultura Livres de Soro , Ciclofosfamida/efeitos adversos , Ciclofosfamida/análogos & derivados , DNA Mitocondrial/efeitos dos fármacos , DNA Mitocondrial/genética , Fator 7 de Crescimento de Fibroblastos/genética , Fator 7 de Crescimento de Fibroblastos/fisiologia , Expressão Gênica , Doenças do Cabelo/induzido quimicamente , Folículo Piloso/crescimento & desenvolvimento , Folículo Piloso/patologia , Humanos , Queratinócitos/efeitos dos fármacos , Queratinócitos/patologia , Camundongos , Modelos Biológicos , Oxirredução , Deleção de SequênciaRESUMO
The role of mitochondria in energy production and apoptosis is well known. The role of mitochondria and particularly the role of the mitochondria's own genome, mitochondrial (mt) DNA, in the process of ageing were postulated decades ago. However, this was discussed, debated and more or less disposed of. Recent data from elegant mouse models now confirm that mutations of mtDNA do indeed play a central and pivotal role in the ageing process. Newer reports also indicate a possible role of mtDNA mutations in the carcinogenesis of several organs. But is damaged mtDNA repaired, or is it simply degraded and discarded? This question appears to be answered now. According to recent data, mitochondria possess functional repair mechanisms such as base excision repair, double-strand break repair and mismatch repair, yet nucleotide excision repair has so far not been detected.
Assuntos
Envelhecimento/fisiologia , Reparo do DNA/fisiologia , DNA Mitocondrial/fisiologia , Neoplasias/genética , Neoplasias/fisiopatologia , Animais , HumanosRESUMO
Mitochondria are responsible for the generation of energy in the form of adenosine triphosphate. These organelles contain their own genetic material, mitochondrial (mt) DNA. This mtDNA has been hypothesized to play a role in the processes of aging and carcinogenesis. Initial reports have shown that there is no repair of cyclobutylpyrimidine dimers (CPD). More recent reports indicate however, that the mitochondrion contains several defence mechanisms against endogenous or exogenous damaging agents such as ultraviolet radiation or oxidative damage. The role of these defence mechanisms in the removal of mitochondrial DNA damage and the link to aging and carcinogenesis-associated processes are discussed in this review.