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1.
Br J Dermatol ; 164(3): 633-6, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21375515

RESUMEN

BACKGROUND: The sap from Euphorbia peplus, commonly known as petty spurge in the U.K. or radium weed in Australia, has been used as a traditional treatment for a number of cancers. OBJECTIVE: To determine the effectiveness of E. peplus sap in a phase I/II clinical study for the topical treatment of basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and intraepidermal carcinomas (IEC). METHODS: Thirty-six patients, who had refused, failed or were unsuitable for conventional treatment, were enrolled in a phase I/II clinical study. A total of 48 skin cancer lesions were treated topically with 100-300 µL of E. peplus sap once daily for 3 days. RESULTS: The complete clinical response rates at 1 month were 82% (n = 28) for BCC, 94% (n = 16) for IEC and 75% (n = 4) for SCC. After a mean follow-up of 15 months these rates were 57%, 75% and 50%, respectively. For superficial lesions < 16 mm, the response rates after follow-up were 100% for IEC (n = 10) and 78% for BCC (n = 9). CONCLUSIONS: The clinical responses for these relatively unfavourable lesions (43% had failed previous treatments, 35% were situated in the head and neck region and 30% were > 2 cm in diameter), are comparable with existing nonsurgical treatments. An active ingredient of E. peplus sap has been identified as ingenol mebutate (PEP005). This clinical study affirms community experience with E. peplus sap, and supports further clinical development of PEP005 for the treatment of BCC, SCC and IEC.


Asunto(s)
Carcinoma in Situ/tratamiento farmacológico , Carcinoma Basocelular/tratamiento farmacológico , Carcinoma de Células Escamosas/tratamiento farmacológico , Euphorbiaceae , Extractos Vegetales/uso terapéutico , Neoplasias Cutáneas/tratamiento farmacológico , Administración Tópica , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma in Situ/patología , Carcinoma Basocelular/patología , Carcinoma de Células Escamosas/patología , Estudios de Cohortes , Humanos , Persona de Mediana Edad , Fitoterapia/métodos , Neoplasias Cutáneas/patología
2.
Med Chem ; 2(2): 123-32, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16787361

RESUMEN

Here we describe the rational design, computer-aided virtual ligand docking and synthesis of 19 nonpeptidic compounds designed to inhibit histone deacetylases and kill melanoma cells. Compounds were derived from cysteine, fused at the S-terminus to 4-butanoyl hydroxamate, and at the N-terminus to 4-(dimethylamino)benzoic acid. The latter was extended by coupling to amines to form a small library of prospective anti-cancer compounds. Four compounds were cytotoxic at sub-micromolar concentrations against cells of a particularly aggressive human melanoma (MM96L), and nine compounds showed selectivities of >or=5:1 for killing human melanoma instead of normal human fibroblast cells. The most active compounds were shown to cause hyperacetylation of histones due to inhibition of histone deacetylases. Further refinement of these compounds may produce an anti-tumor drug suitable for treating melanoma.


Asunto(s)
Antineoplásicos/farmacología , Proliferación Celular/efectos de los fármacos , Cisteína/farmacología , Inhibidores Enzimáticos/farmacología , Antineoplásicos/síntesis química , Línea Celular Tumoral , Cisteína/análogos & derivados , Cisteína/síntesis química , Diseño de Fármacos , Fibroblastos/citología , Fibroblastos/metabolismo , Inhibidores de Histona Desacetilasas , Histona Desacetilasas/metabolismo , Humanos , Melanoma/patología , Modelos Químicos
3.
Mol Pharmacol ; 60(4): 828-37, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11562446

RESUMEN

Histone deacetylase inhibitors show promise as chemotherapeutic agents and have been demonstrated to block proliferation in a wide range of tumor cell lines. Much of this antiproliferative effect has been ascribed to the up-regulated expression of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1). In this article, we report that p21 expression was up-regulated by relatively low doses of the histone deacetylase inhibitor azelaic bishydroxamic acid (ABHA) and correlated with a proliferative arrest. Higher doses of ABHA were cytotoxic. Cells that did not up-regulate p21 expression were hypersensitive to killing by ABHA and died via apoptosis, whereas up-regulation of p21 correlated with reduced sensitivity and a block in the apoptotic mechanism, and these cells seemed to die by necrosis. Using isogenic p21(+/+) and p21(-/-) cell lines and direct inhibition of caspase activity, we demonstrate that the reduced sensitivity to killing by ABHA is a consequence of inhibition of apoptosis by up-regulated p21 expression. These data indicate the enormous potential of therapeutic strategies that bypass the cytoprotective effect of p21 and act on the same molecular targets as the histone deacetylase inhibitors.


Asunto(s)
Apoptosis , Ciclinas/metabolismo , Inhibidores Enzimáticos/farmacología , Inhibidores de Histona Desacetilasas , Ácidos Hidroxámicos/farmacología , Compuestos de Boro , Ciclo Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Inhibidor p21 de las Quinasas Dependientes de la Ciclina , Ciclinas/fisiología , Células HeLa , Humanos , Metacrilatos , Metilmetacrilatos , Células Tumorales Cultivadas , Regulación hacia Arriba/efectos de los fármacos
4.
J Invest Dermatol ; 116(2): 224-9, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11179997

RESUMEN

MC1R gene variants have previously been associated with red hair and fair skin color, moreover skin ultraviolet sensitivity and a strong association with melanoma has been demonstrated for three variant alleles that are active in influencing pigmentation: Arg151Cys, Arg160Trp, and Asp294His. This study has confirmed these pigmentary associations with MC1R genotype in a collection of 220 individuals drawn from the Nambour community in Queensland, Australia, 111 of whom were at high risk and 109 at low risk of basal cell carcinoma and squamous cell carcinoma. Comparative allele frequencies for nine MC1R variants that have been reported in the Caucasian population were determined for these two groups, and an association between prevalence of basal cell carcinoma, squamous cell carcinoma, solar keratosis and the same three active MC1R variant alleles was demonstrated [odds ratio = 3.15 95% CI (1.7, 5.82)]. Three other commonly occurring variant alleles: Val60Leu, Val92Met, and Arg163Gln were identified as having a minimal impact on pigmentation phenotype as well as basal cell carcinoma and squamous cell carcinoma risk. A significant heterozygote effect was demonstrated where individuals carrying a single MC1R variant allele were more likely to have fair and sun sensitive skin as well as carriage of a solar lesion when compared with those individuals with a consensus MC1R genotype. After adjusting for the effects of pigmentation on the association between MC1R variant alleles and basal cell carcinoma and squamous cell carcinoma risk, the association persisted, confirming that presence of at least one variant allele remains informative in terms of predicting risk for developing a solar-induced skin lesion beyond that information wained through observation of pigmentation phenotype.


Asunto(s)
Carcinoma Basocelular/genética , Carcinoma de Células Escamosas/genética , Receptores de Corticotropina/genética , Neoplasias Cutáneas/genética , Alelos , Carcinoma Basocelular/epidemiología , Carcinoma de Células Escamosas/epidemiología , Variación Genética/genética , Genotipo , Humanos , Fenotipo , Queensland/epidemiología , Receptores de Melanocortina , Factores de Riesgo , Neoplasias Cutáneas/epidemiología , Pigmentación de la Piel/genética , Pigmentación de la Piel/efectos de la radiación , Rayos Ultravioleta
5.
Eur J Biochem ; 267(21): 6413-22, 2000 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11029584

RESUMEN

The class III POU gene brn-2, encoding the Brn-2/N-Oct-3 transcription factor, is widely expressed in the developing mammalian central nervous system. Brn-2 has also been found to regulate the melanocytic phenotype with N-Oct-3 DNA binding activity elevated in malignant melanoma, however, its mode of action is yet to be defined. The functional role of the Brn-2 transcription factor has been investigated through the analysis of protein-protein interactions it forms with a number of basal and melanocytic transcriptional regulatory proteins. In vivo interactions were tested by gene-cotransfection using the mammalian GAL4-Herpes Simplex viral protein 16 (VP16) two hybrid formation and direct protein binding by in vitro glutathione S-transferase (GST)-pull down assay. The Brn-2 protein was found to homodimerize in vivo with high affinity, using Brn-2 deletion constructs dimer complex formation was found to be dependent on the presence of both the homeodomain and linker regions of the POU-domain. However, the POU-homoedomain was dispensable for the formation of the dimerization interface in one of the partner molecules but not both, when the POU-linker region was removed the ability to interact was lost irrespective of the presence of the homeodomain. Dimerization of Brn-2/N-Oct-3 was also found to occur in DNA binding assays using melanoma cell line nuclear extracts and a recently reported dimer target sequence probe, which may have significant consequences for gene regulation in melanocytic tumours. Low affinity Brn-2 protein contacts have also been found with the basal transcription complex, including TATA binding protein (TBP) and the transcriptional coactivator p300, and with the Sox-10 and Pax-3 transcription factors that are known to play an important role in melanocyte cell formation.


Asunto(s)
Factores de Transcripción/química , Factores de Transcripción/metabolismo , Sitios de Unión , Extractos Celulares , ADN/genética , ADN/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Dimerización , Proteínas del Grupo de Alta Movilidad/genética , Proteínas del Grupo de Alta Movilidad/metabolismo , Proteínas de Homeodominio , Humanos , Melanoma/metabolismo , Melanoma/patología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Factor 3 de Transcripción de Unión a Octámeros , Factor de Transcripción PAX3 , Factores del Dominio POU , Factores de Transcripción Paired Box , Unión Proteica , Estructura Terciaria de Proteína , Factores de Transcripción SOXE , Eliminación de Secuencia/genética , Proteína de Unión a TATA-Box , Moldes Genéticos , Transactivadores/genética , Transactivadores/metabolismo , Factor de Transcripción TFIIB , Factores de Transcripción/genética , Células Tumorales Cultivadas
6.
Int J Parasitol ; 30(6): 761-8, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10856511

RESUMEN

The histones of Plasmodium falciparum represent a potential new target for anti-malarial compounds. A naturally occurring compound, apicidin, has recently been shown to inhibit the in vitro growth of P. falciparum. Apicidin was shown to hyperacetylate histones, suggesting that its mode of action is through histone deacetylase inhibition. We have tested the ability of known histone deacetylase inhibitors, mammalian tumour suppressor compounds, and cytodifferentiating agents to inhibit the in vitro growth of a drug sensitive and resistant strain of P. falciparum. Seven of the tested compounds had microM IC50 values, and trichostatin A, a histone deacetylation inhibitor and cytodifferentiating agent, was active at low nM concentrations. One compound, suberic acid bisdimethylamide, which selectively arrests tumour cells as opposed to normal mammalian cells, had an in vivo cytostatic effect against the acute murine malaria Plasmodium berghei, and one round of treatment with the compound failed to select for resistant mutations. These results suggest a promising role for histone deacetylase inhibitors and cytodifferentiating agents as antimalarial drug candidates.


Asunto(s)
Antimaláricos/farmacología , Inhibidores Enzimáticos/farmacología , Inhibidores de Histona Desacetilasas , Plasmodium berghei/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Acetamidas/farmacología , Animales , Antineoplásicos/farmacología , Azacitidina/farmacología , Diferenciación Celular/efectos de los fármacos , Metilación de ADN , Femenino , Hematínicos/farmacología , Ácidos Hidroxámicos/química , Ácidos Hidroxámicos/farmacología , Ratones , Ratones Endogámicos BALB C , Plasmodium berghei/crecimiento & desarrollo
7.
Mol Biol Cell ; 11(6): 2069-83, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10848630

RESUMEN

Important aspects of cell cycle regulation are the checkpoints, which respond to a variety of cellular stresses to inhibit cell cycle progression and act as protective mechanisms to ensure genomic integrity. An increasing number of tumor suppressors are being demonstrated to have roles in checkpoint mechanisms, implying that checkpoint dysfunction is likely to be a common feature of cancers. Here we report that histone deacetylase inhibitors, in particular azelaic bishydroxamic acid, triggers a G2 phase cell cycle checkpoint response in normal human cells, and this checkpoint is defective in a range of tumor cell lines. Loss of this G2 checkpoint results in the tumor cells undergoing an aberrant mitosis resulting in fractured multinuclei and micronuclei and eventually cell death. This histone deacetylase inhibitor-sensitive checkpoint appears to be distinct from G2/M checkpoints activated by genotoxins and microtubule poisons and may be the human homologue of a yeast G2 checkpoint, which responds to aberrant histone acetylation states. Azelaic bishydroxamic acid may represent a new class of anticancer drugs with selective toxicity based on its ability to target a dysfunctional checkpoint mechanism in tumor cells.


Asunto(s)
Inhibidores Enzimáticos/farmacología , Inhibidores de Histona Desacetilasas , Ácidos Hidroxámicos/farmacología , Transducción de Señal/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Fase G1/efectos de los fármacos , Fase G2/efectos de los fármacos , Células HeLa , Humanos , Mitosis/efectos de los fármacos , Células Tumorales Cultivadas
8.
J Invest Dermatol ; 114(1): 21-7, 2000 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-10620110

RESUMEN

In studies to determine whether pigmentation can be regulated physiologically by thiols, human melanoma cells (MM418c5) and melanocytes were found to become depigmented when cultured continuously in 50 microM cystamine. Cystamine was depleted from the culture medium and the treatment was nontoxic and reversible. Cysteamine, dithiothreitol, and phenylthiourea were less effective, and glutathione, cysteine, and cystine were inactive. Tyrosinase (dopa oxidase) activity was not greatly affected except for induction of a lag period. In contrast, tyrosinase activity in an amelanotic melanoma cell line (MM96L) was rapidly inhibited without consumption of cystamine/cysteamine, in association with the generation of free thiol in the culture medium, and could be enhanced by the cystine transport inhibitor, glutamate. Tyrosinase expressed by a recombinant vaccinia virus was inhibited by cystamine treatment of MM96L and HeLa cells. Cystamine treatment lowered the degree of cross-linking of the pigmentation antigen gp75/TRP-1 in MM418c5 cells. Tyrosinase protein and mRNA levels in MM418c5 cells were not affected by cystamine. The results show that cystamine at a concentration close to physiologic levels has multiple effects on the melanogenic pathway. In amelanotic cells, tyrosinase has a short half-life and is readily inhibited by cystamine/cysteamine whereas tyrosinase in the more mature melanosomes of the pigmented cell appears to be less accessible to proteolytic and thiol attack. Inhibition of melanin synthesis in the latter cell type may arise to a significant degree from reduction of cystamine to cysteamine, which sequesters quinones.


Asunto(s)
Cistamina/farmacología , Melaninas/antagonistas & inhibidores , Melanoma/metabolismo , Neoplasias Cutáneas/metabolismo , Células HeLa , Humanos , Melaninas/biosíntesis , Melanocitos/fisiología , Melanoma/patología , Melanoma/fisiopatología , Monofenol Monooxigenasa/genética , Monofenol Monooxigenasa/metabolismo , Pigmentación , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/fisiopatología , Compuestos de Sulfhidrilo/metabolismo , Compuestos de Sulfhidrilo/fisiología , Transcripción Genética/fisiología , Células Tumorales Cultivadas
9.
Arch Dermatol Res ; 291(9): 511-6, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10541882

RESUMEN

The distribution of melanocytes in human skin has been observed to vary within and among individuals, yet little is known of the factors that determine the density of these pigment cells. These factors were explored in a molecular epidemiological study conducted among a population-based sample of 97 male subjects aged over 50 years in Queensland, Australia. Information relating to environmental and phenotypic factors was collected through face-to-face interviews and physical examination of all participants. In addition, 2-mm biopsies of representative skin were taken from the dorsum of the hand and another anatomical site. Melanocytes were identified by cytoplasmic staining with the B8G3 (anti-TRP1) monoclonal antibody using standard immunohistochemical techniques. Melanocyte counts were performed blind by two observers. On crude analysis, melanocyte density decreased with advancing age (P = 0.0002), and increased with increasing number of naevi (P = 0.01). Other pigmentary characteristics (such as hair and eye colour and depth of tan) were not associated with epidermal melanocyte density. Melanocyte density varied significantly by anatomical site (P = 0.02), with highest densities observed on the back/shoulders (n = 50, 17.1 +/- 8.8 cells/mm, mean +/- SD) followed by the upper limbs (n = 11, 12.6 +/- 8.8 cells/mm) and lower limbs (n = 14, 14.4 +/- 5.9 cells/mm). Lowest melanocyte densities were recorded on the anterior trunk (n = 3, 3.2 +/- 2.4 cells/mm). These findings confirm the results of earlier studies in which site-specific differences in melanocyte density have been found. We speculate that the unequal distribution of melanocytes may partially explain the site-specific incidence of melanoma, offering fresh perspectives on the aetiology of this cancer.


Asunto(s)
Melanocitos/citología , Piel/citología , Envejecimiento/fisiología , Análisis de Varianza , Dorso , Recuento de Células , Extremidades , Mano , Humanos , Masculino , Melanocitos/fisiología , Persona de Mediana Edad , Fenotipo , Análisis de Regresión , Hombro , Tórax
10.
Biochem Pharmacol ; 58(3): 383-8, 1999 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-10424756

RESUMEN

The ultimate target of pharmacological research is to find new drugs for treating human diseases such as cancer. Agents causing differentiation and thus growth arrest should be particularly useful in this regard. A potential target for such anticancer therapy is the enzyme family protein kinase C (PKC), which is involved in the transduction of signals for cell proliferation, differentiation, and apoptosis. Our recent work showing the induction of differentiation in melanoma cells by an activator of one PKC isoform, PKCdelta, touches on several important areas of investigation, which will form the basis of this review: the role of individual isoforms of PKC, their downstream targets and their specific substrates, the mechanism of activation of specific genes involved in the differentiation process, and the molecular basis for the morphological changes associated with differentiation. The central role that PKC plays in these processes points to the need for a greater understanding of the signalling pathways utilized by individual isoforms of this family of enzymes.


Asunto(s)
Diferenciación Celular , Neoplasias/enzimología , Proteína Quinasa C/metabolismo , Antineoplásicos/farmacología , Regulación Neoplásica de la Expresión Génica , Humanos , Isoenzimas/metabolismo , Neoplasias/patología , Proteína Quinasa C/clasificación , Transducción de Señal/fisiología
11.
Br J Cancer ; 80(8): 1252-8, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10376979

RESUMEN

A series of hydroxamates, which are not metalloprotease inhibitors, have been found to be selectively toxic to a range of transformed and human tumour cells without killing normal cells (fibroblasts, melanocytes) at the same concentrations. Within 24 h of treatment, drug action is characterized by morphological reversion of tumour cells to a more normal phenotype (dendritic morphology), and rapid and reversible acetylation of histone H4 in both tumour and normal cells. Two hydroxamates inhibited growth of xenografts of human melanoma cells in nude mice; resistance did not develop in vivo or in vitro. A third hydroxamate, trichostatin A, was active in vitro but became inactivated and had no anti-tumour activity in vivo. Development of dendritic morphology was found to be dependent upon phosphatase activity, RNA and protein synthesis. Proliferating hybrid clones of sensitive and resistant cells remained sensitive to ABHA, indicating a dominant-negative mechanism of sensitivity. Histone H4 hyperacetylation suggests that these agents act at the chromatin level. This work may lead to new drugs that are potent, and selective anti-tumour agents with low toxicity to normal cells.


Asunto(s)
Ácidos Hidroxámicos/farmacología , Melanoma/patología , Neoplasias Cutáneas/patología , Animales , Diferenciación Celular/efectos de los fármacos , Supervivencia Celular , Células Dendríticas/efectos de los fármacos , Células Dendríticas/fisiología , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Ratones , Ratones Desnudos , Trasplante Heterólogo , Células Tumorales Cultivadas/efectos de los fármacos , Ensayo de Tumor de Célula Madre
12.
Photochem Photobiol ; 69(5): 611-6, 1999 May.
Artículo en Inglés | MEDLINE | ID: mdl-10333769

RESUMEN

Reports of systemic absorption of sunscreens prompted a study of the effects of emulsions of 3 commonly used sunscreens on cultured human cells; vegetable oil and paraffin oil were used as controls. Ethylhexyl p-methoxycinnamate (EHMC), octyl p-dimethylaminobenzoate (PABA) and oxybenzone (OB) inhibited cell growth and DNA synthesis and retarded cycle progression from G1 in the dose range 25-100 micrograms/mL. An extended period of exposure (up to 24 h) was required for maximum uptake of sunscreens and for inhibition of cell growth. Melano-cytes and fibroblasts tended to be more resistant than tumor cell lines (melanoma, cervical carcinoma). Sunscreens had no major effects on the transcription of certain genes, as judged by the activity of reporter constructs driven by the p53, c-fos and metal response (sheep metallothionein Ia promoter) elements and transfected into a human melanoma cell line (MM96L). The activity of the cytomegalovirus promoter was also not affected. A cell line (CI80-13S) with mitochondrial dysfunction was significantly more sensitive to growth inhibition by EHMC and PABA than the other cell lines tested. Treatment of MM96L with the mitochondrial inhibitor ethidium bromide sensitized the cells to killing by cotreatment with sunscreens, in association with increased cellular uptake of ethidium bromide. These results established conditions for studying the action of sunscreens on cultured human cells. Further studies are required to determine whether the mitochondrial stress and changes in drug uptake associated with sunscreens in the above cell lines are relevant to their action in vivo.


Asunto(s)
Ciclo Celular/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Cationes , Replicación del ADN/efectos de los fármacos , Humanos , Transporte Iónico , Protectores Solares/toxicidad , Células Tumorales Cultivadas
13.
J Invest Dermatol ; 111(6): 936-40, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9856799

RESUMEN

Epidemiology shows a relationship between solar exposure and all types of skin cancer. Understanding the mechanisms of skin cancer requires knowledge of the photomolecular events that occur within the relevant epidermal cell types in vivo. Studies to date have focused on UVR-induced DNA lesions in keratinocytes, the majority epidermal cell population which gives rise to most skin cancers. Malignant melanoma, arising from melanocytes (5%-10% of epidermal cells), accounts for most skin cancer deaths. We report on new techniques to detect DNA photolesions in human epidermal melanocytes in situ. Previously nonexposed buttock skin of volunteers of skin types I/II was exposed to clinically relevant doses of narrow bandwidth UVB (300 nm) and UVA (320 nm, 340 nm, 360 nm) radiation. Biopsies were taken immediately afterwards and processed for routine histology. Microscope sections were prepared and double-stained with fluorescent-tagged monoclonal antibodies for thymine dimers and melanocytes. UVR dose-response curves for dimer levels within melanocyte nuclei were determined by image analysis and compared with dimer levels in adjacent basal cell keratinocytes. Our data show that UVB and UVA readily induce thymine dimers in melanocytes at levels that are comparable with those found in adjacent keratinocytes. This new technique will enable melanocyte specific studies, such as DNA repair kinetics, to be done in vivo.


Asunto(s)
Queratinocitos/efectos de la radiación , Melanocitos/efectos de la radiación , Dímeros de Pirimidina/análisis , Rayos Ultravioleta , Adulto , Anticuerpos Monoclonales , Reparación del ADN , Relación Dosis-Respuesta en la Radiación , Fluorescencia , Humanos , Queratinocitos/química , Modelos Lineales , Melanocitos/química
14.
Int J Cancer ; 77(6): 843-8, 1998 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-9714052

RESUMEN

Epidemiological data strongly implicate sunlight as the principal environmental cause of melanoma; however, critical molecular targets for ultraviolet (UV)-induced melanoma remain to be identified. The p53 tumor suppressor gene is one possible target, being abnormally expressed in 20-40% of primary melanomas. We undertook a population-based molecular epidemiological study with the aim of determining the environmental and phenotypic factors associated with p53-positive and p53-negative melanomas. One hundred fifty cases of melanoma were randomly ascertained from the Queensland Cancer Registry and matched to 150 electoral roll controls. Data on environmental and phenotypic exposures were collected through interviews and physical examination of all participants. Sections of tumor tissue were obtained from 134 (89%) cases and stained with the anti-p53 DO-7 monoclonal antibody (MAb) following microwave antigen retrieval. Of 121 useable sections, 22 tumors (18%) had more than 1% cells with positive staining consistent with abnormalities in p53 expression. Strongest predictors of p53-positive melanoma were inability to tan [odds ratio (OR) 6.8], history of non-melanoma skin cancer (OR 3.2) and site of melanoma: head/neck (OR 2.2) and lower limbs (OR 2.3). In contrast, factors such as nevus density and freckling propensity were strongly associated only with p53-immunonegative melanoma (OR 8.6 for >25 moles; OR 3.0 for heavy facial freckling). Overall, the determinants of p53-positive and p53-negative melanomas were independent and complementary, the former being associated with features of sun-sensitivity and chronic sun exposure, the latter with phenotypic markers of melanocytic proliferation. Our findings are consistent with at least 2 independent pathways in the pathogenesis of melanoma, characterized by environmental induction and p53 overexpression on the one hand and pigment cell instability on the other.


Asunto(s)
Regulación Neoplásica de la Expresión Génica , Melanoma/química , Neoplasias Cutáneas/química , Proteína p53 Supresora de Tumor/análisis , Distribución por Edad , Anticuerpos Monoclonales , Estudios de Casos y Controles , Humanos , Masculino , Melanoma/epidemiología , Melanoma/genética , Persona de Mediana Edad , Oportunidad Relativa , Fenotipo , Estudios Prospectivos , Queensland/epidemiología , Sistema de Registros , Factores de Riesgo , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/genética
15.
Med J Aust ; 168(7): 327-30, 1998 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-9577442

RESUMEN

OBJECTIVE: To determine the value of shade in protecting humans from solar ultraviolet (UV) radiation. DESIGN AND SETTING: Measurement with photometers of protection factors for ultraviolet B radiation (UVB) and for total solar radiation for different types of trees and other structures during the summer months (1995-1997) in south-east Queensland. (The protection ratio is the ratio of the intensity of UVB or total solar radiation in direct sunlight to that in shade.) RESULTS: For summer sun at midday, the mean (SD) UV protection ratio for the shade of trees (n = 65) was 4.21 (1.36) on a horizontal surface and 1.33 (0.30) on a vertical surface. In contrast, the mean (SD) protection ratio for total solar energy (primarily infrared) was much higher (12.1 [1.4]). Trees common in recreational areas in Australia (eucalypts: UV protection ratio, 3.52 [0.79]; Norfolk Island pines: UV protection ratio, 3.72 [0.98]) offered reduced protection compared with trees with more dense foliage (UV protection ratio, 5.48 [1.44]). Over a whole day, measurement of shade by trees and other structures showed that the UV protection ratio was lower in the morning and afternoon. Shade from awnings, buildings and hats gave similar results to those for trees. Both at midday and over a whole day satisfactory protection (UV protection ratio > 15) was obtained only in shade which eliminated exposure to the sky as well as to direct sunlight; for example, in thickly wooded areas and under low, widely overhanging structures. CONCLUSIONS: Most forms of shade, while useful, offer people insufficient protection from solar UV. A fair-skinned person sheltering under a tree could suffer sunburn after less than one hour. There is a need for appropriate design of structural shade, use of other solar protection measures in conjunction with shade, and research on behavioural responses to shade.


Asunto(s)
Quemadura Solar/prevención & control , Árboles , Rayos Ultravioleta/efectos adversos , Arquitectura y Construcción de Instituciones de Salud/normas , Humanos , Fotometría , Ropa de Protección/normas , Queensland , Factores de Riesgo , Pigmentación de la Piel , Quemadura Solar/etiología , Factores de Tiempo
16.
Melanoma Res ; 8(1): 2-10, 1998 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9508370

RESUMEN

Reversible oxidation sensitivity of N-Oct-3 DNA binding activity was seen when melanoma extracts and recombinant Brn-2 protein were treated with a variety of metals, hydrogen peroxide and the cysteine disulphide bond forming agent diamide. Western blot analysis of diamide-oxidized N-Oct-3 protein indicated that this was likely to be due to intramolecular disulphide bonding. The potential role of oxidative loss of N-Oct-3 DNA binding activity is discussed in relation to redox changes that may occur during the early phase of apoptosis in neuronal cell lines and tissues. Brn-2 C-terminal antibody Western blot analysis of melanoma cell line nuclear extracts prepared using a combination of sodium dodecyl sulphate and NP-40 detergent cell lysis procedures demonstrated the formation of N-Oct-5 DNA binding activity via N-terminal proteolytic clipping of Brn-2/N-Oct-3.


Asunto(s)
ADN de Neoplasias/metabolismo , Proteínas de Unión al ADN/metabolismo , Regulación Neoplásica de la Expresión Génica , Melanoma Experimental/genética , Melanoma/genética , Factores de Transcripción/metabolismo , Animales , Western Blotting , Células COS , Núcleo Celular/química , Núcleo Celular/genética , ADN de Neoplasias/aislamiento & purificación , Diamida/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Células HeLa , Proteínas de Homeodominio , Humanos , Peróxido de Hidrógeno/farmacología , Metales , Ratones , Oxidación-Reducción , Factores del Dominio POU , Conejos , Células Tumorales Cultivadas
17.
Melanoma Res ; 8(1): 67-75, 1998 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9508380

RESUMEN

The mechanism of action of fotemustine, a relatively new chloroethylnitrosourea, was evaluated in human melanoma cells in order to assess its potential as an agent for hyperthermic limb perfusion. Fotemustine was more toxic to O6-alkylguanine methyl transferase (AGT) deficient (Mer-) cells than Mer+ cells, implicating AGT as a major determinant of resistance. Mer+ cells derived from Mer- cell lines following exposure to the monofunctional alkylating metabolite of dacarbazine (DTIC) were also resistant to fotemustine. Mer status did not influence the replication of fotemustine-damaged adenovirus 5, whereas virus treated with the monofunctional alkylating agent N-methyl-N1-nitro-N-nitrosoguanidine (MNNG) was replicated much more efficiently by Mer+ cells. This suggests that the initial O6-alkylated product, if not immediately repaired, rearranges to form DNA crosslinks which cannot be repaired by AGT. Replication of a control virus was not affected by treating the cells with fotemustine, indicating that the drug acted primarily on DNA rather than at epigenetic levels. Fotemustine generally produced a G2-M block in the cell cycle, most strikingly in Mer- cells at low, minimally toxic concentrations; MNNG and high doses of fotemustine induced S phase arrest. Concurrent hyperthermia (41.5 degrees C for 1 h) increased the toxicity of fotemustine in some cell lines. Fotemustine decomposed in culture medium in two phases; the first was complete within 5 min and was most marked in Mer+ cells. The results suggest that fotemustine may be suitable for isolated limb perfusion in melanoma, with the potential for overcoming resistance by including inhibitors of AGT.


Asunto(s)
Antineoplásicos/toxicidad , Melanoma/tratamiento farmacológico , Compuestos de Nitrosourea/toxicidad , Compuestos Organofosforados/toxicidad , Neoplasias Cutáneas/tratamiento farmacológico , Adenoviridae/fisiología , Carcinógenos/toxicidad , Ciclo Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , ADN de Neoplasias/efectos de los fármacos , Evaluación de Medicamentos , Humanos , Hipertermia Inducida , Melanoma/enzimología , Melanoma/patología , Melanoma/virología , Metilnitronitrosoguanidina/toxicidad , O(6)-Metilguanina-ADN Metiltransferasa/metabolismo , Perfusión , Neoplasias Cutáneas/enzimología , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/virología , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/enzimología , Células Tumorales Cultivadas/patología , Células Tumorales Cultivadas/virología , Replicación Viral/efectos de los fármacos
18.
Int J Cancer ; 75(4): 590-5, 1998 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-9466661

RESUMEN

Potentiation of immunogenicity of malignant cells by gene transduction provides a unique opportunity for immune targeting of human cancers in vivo. This approach is undoubtedly influenced by the ability of the malignant cells to process and present endogenously target epitopes on their cell surface for immune recognition by cytotoxic T lymphocytes (CTLs). In the present study, we have investigated potential immune-resistance pathways in human malignant melanoma by analyzing the major histocompatibility complex (MHC) gene expression and function in a panel of tumour cell lines. Our analysis showed that a large proportion of these cell lines consistently display a functional defect in the endogenous processing of CTL epitopes and are recognised poorly by specific T cells in spite of high levels of target antigen expression in the tumour cells. Molecular characterisation of this defect revealed that tumour cells under-expressed peptide transporters and surface-assembled MHC class I molecules, which constitute essential components of the class I processing pathway. Induction of peptide transporter and surface class I following treatment of these tumour cells with interferon gamma (IFN-gamma) suggested a transcriptional defect in the expression of antigen-processing genes. Endogenous processing function in these tumour cells was restored completely following simultaneous transduction of cells with peptide transporter and HLA class I genes. Our findings provide a rationale for focussing on strategies designed to improve antigen-processing function in tumour cells and, thus, may strongly influence future strategies for melanoma-specific immunotherapy.


Asunto(s)
Transportadoras de Casetes de Unión a ATP/fisiología , Células Presentadoras de Antígenos/inmunología , Citotoxicidad Inmunológica , Proteínas de la Matriz Extracelular/fisiología , Antígenos de Histocompatibilidad Clase I/fisiología , Melanoma/inmunología , Proteínas del Tejido Nervioso/fisiología , Linfocitos T Citotóxicos , Transportador de Casetes de Unión a ATP, Subfamilia B, Miembro 2 , Miembro 3 de la Subfamilia B de Transportadores de Casetes de Unión a ATP , Genes MHC Clase I , Humanos , Interferón gamma/farmacología , Transducción Genética , Células Tumorales Cultivadas , Virus Vaccinia
19.
Mutat Res ; 422(1): 31-41, 1998 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-9920426

RESUMEN

Analysis of the expression of a number of known genes in cultured human cells has revealed UVB-induced changes that may be specific for melanocytic cells. The response of c-fos, p53 and HIV-LTR reporter constructs to UVB and UVC was reduced in MM96L melanoma cells compared to HeLa. Cell cycle arrest produced by UVA, gamma radiation, cisplatin or the antimetabolite deoxyinosine differed from that of UVB. Cell cycle analysis after multiple doses of UVB raised the possibility that UVB-induced pRb depletion could result in increased mutation and thus enhanced tumourigenesis of irradiated melanocytes in skin subjected to a defined pattern of UVB exposure. To extend the analysis of gene expression in cultured melanocytic cells to uncharacterised genes, promoter trap cell clones containing unknown genes 'tagged' by a beta-galactosidase reporter construct were generated from MM96L cells. Altered gene expression in clones treated with a panel of DNA-damaging agents was quantitated by measurement of beta-galactosidase activity. Of the clones containing 'tagged' endogenous promoters induced by UVB, 52% were induced only by UVB and not by other DNA-damaging agents (cisplatin, N-methyl-N-nitro-nitrsoguanidine, fotemustine). One third of the clones were also activated by TPA suggesting that general DNA damage responses involving PKC are activated less frequently than unique pathways of gene activation. Overall, 60% of the 50 clones that responded to the panel of agents were induced by only one of the agents, indicating that a high proportion of genes are induced by agent-specific mechanisms. In the long term, promoter trapping may allow the full repertoire of UVB-inducible genes to be characterised.


Asunto(s)
Melanocitos/efectos de la radiación , Melanoma/etiología , Neoplasias Inducidas por Radiación/patología , Neoplasias Cutáneas/etiología , Rayos Ultravioleta , Antineoplásicos/toxicidad , Ciclo Celular/efectos de los fármacos , Ciclo Celular/efectos de la radiación , Cisplatino/toxicidad , Demecolcina/farmacología , Genes fos , Genes p53 , Duplicado del Terminal Largo de VIH , Células HeLa , Humanos , Hidroxiurea/farmacología , Inosina/análogos & derivados , Inosina/farmacología , Melanocitos/citología , Melanocitos/efectos de los fármacos , Melanoma/patología , Metilnitronitrosoguanidina/toxicidad , Compuestos de Nitrosourea/toxicidad , Compuestos Organofosforados/toxicidad , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Recombinantes/biosíntesis , Neoplasias Cutáneas/patología , Acetato de Tetradecanoilforbol/toxicidad , Transfección , Células Tumorales Cultivadas , beta-Galactosidasa/genética
20.
Melanoma Res ; 8(6): 471-81, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9918408

RESUMEN

In human melanocytes and a human melanoma cell line (MM96L), the level of Ku sequence-specific binding to a 37-mer oligonucleotide containing a single E2F-1 binding site of the c-myc promoter (E2cM) significantly decreased 12 24h after cytostatic exposure to 300 J/m2 ultraviolet B radiation (UVB). No UVB-induced loss was found in fibroblasts, while HeLa cells showed an earlier (4 h) but less significant decrease than melanocytic cells. Equitoxic doses of gamma radiation, cisplatin or UVC had little effect on E2cM-specific binding. The loss of Ku binding in MM96L cells was not the result of translocation of Ku or a decrease in Ku protein or DNA-dependent protein kinase activity. The level of E2cM-specific binding in MM96L cells was increased by tunicamycin (2 microg/ml), an inhibitor of N-linked glycosylation, and decreased by the glucosidase inhibitor castanospermine (50 microg/ml). These results, which parallel the reported loss in melanocytes of the cell cycle regulator pRB after UVB, suggest that the DNA binding activity of Ku is affected by post-translational modification and may play a role in regulating the cell cycle response to UVB.


Asunto(s)
Antígenos Nucleares , Proteínas Portadoras , Proteínas de Ciclo Celular , ADN Helicasas , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/efectos de la radiación , Melanocitos/efectos de la radiación , Proteínas Nucleares/metabolismo , Proteínas Nucleares/efectos de la radiación , Factores de Transcripción/metabolismo , Anticuerpos Monoclonales/metabolismo , Western Blotting , Ciclo Celular/efectos de la radiación , Factores de Transcripción E2F , Factor de Transcripción E2F1 , Electroforesis en Gel de Poliacrilamida , Inhibidores Enzimáticos/farmacología , Células HeLa , Humanos , Indolizinas/metabolismo , Autoantígeno Ku , Melanoma/metabolismo , Unión Proteica/efectos de la radiación , Proteínas Quinasas/efectos de la radiación , Proteína de Retinoblastoma/efectos de la radiación , Proteína 1 de Unión a Retinoblastoma , Factor de Transcripción DP1 , Células Tumorales Cultivadas , Tunicamicina/metabolismo , Rayos Ultravioleta
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