RESUMEN
BACKGROUND: Epigenetic variation is a main regulation mechanism of gene expression in various cancer histotypes, and due to its reversibility, the potential impact in therapy can be very relevant. METHODS: Based on a selected pair, breast cancer (BC) and melanoma, we conducted inference analysis in parallel on a few cell lines (MCF-7 for BC and A375 for melanoma). Starting from differential expression after treatment with a demethylating agent, the 5-Aza-2'-deoxycytidine (DAC), we provided pathway enrichment analysis and gene regulatory maps with cross-linked microRNAs and transcription factors. RESULTS: Several oncogenic signaling pathways altered upon DAC treatment were detected with significant enrichment. We represented the association between these cancers by depicting the landscape of common and specific variation affecting them.
Asunto(s)
Neoplasias de la Mama/genética , Epigénesis Genética , Melanoma/genética , Transducción de Señal/genética , Azacitidina/análogos & derivados , Azacitidina/farmacología , Azacitidina/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Línea Celular Tumoral , Decitabina , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Epigénesis Genética/efectos de los fármacos , Femenino , Redes Reguladoras de Genes/efectos de los fármacos , Genes Relacionados con las Neoplasias , Humanos , Melanoma/tratamiento farmacológico , Transducción de Señal/efectos de los fármacos , Transcripción Genética/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genéticaRESUMEN
The immunohistochemical expression of phosphorylated (activated) Akt (pAkt) in 50 advanced gastric carcinomas has been analyzed and the results correlated with age, sex, location in the stomach, histotype, stage, survival, mitotic and apoptotic index, some cell cycle regulators (cyclin D1, cyclin E, p34/cdc2, p27/kip1), and cell proliferation. There was a statistically significant direct correlation between pAkt expression (both cytoplasmatic and nuclear) and depth of infiltration of the tumor, number of infiltrated lymph nodes and p34/cdc2 expression, and between prevalently nuclear pAkt and cyclin D1 and cyclin E. Conversely, there was a significant inverse correlation between nuclear pAkt and apoptotic index and between cytoplasmatic and nuclear pAkt and patient survival. No correlation was found between pAkt and sex, age, tumor location, histotype, mitotic index, and cell proliferation. These findings suggest that pAkt may be considered an indicator of tumor progression and patient survival in gastric cancer.
Asunto(s)
Biomarcadores de Tumor/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Apoptosis , Proteína Quinasa CDC2/metabolismo , Proliferación Celular , Ciclina D1/metabolismo , Ciclina E/metabolismo , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Retrospectivos , Neoplasias Gástricas/patología , Análisis de Supervivencia , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Human retinoblastoma occurs in two forms (familial and sporadic) both due to biallelic mutation of the RB1/p105 gene even if its loss is insufficient for malignancy. We have recently reported that loss of expression of the retinoblastoma-related protein pRb2/p130 correlates with low apoptotic index, suggesting that RB2/p130 gene could be involved in retinoblastoma. Mutational analysis of RB2/p130 in primary tumors showed a tight correlation between Exon 1 mutations and pRb2/p130 expression level in sporadic retinoblastoma. These mutations are located within a CpG-enriched region prone to de novo methylation. Analysis of RB2/p130 methylation status revealed that epigenetic events, most probably consequent to the Exon 1 mutations, determined the observed phenotype. Treatment of Weri-Rb1 cell line by 5-Aza-dC induced an increase in expression level of pRb2/p130, E2F1, p73 and p53. Overall, our results highlight a crucial role of epigenetic events in sporadic retinoblastoma, which opens a perspective for new therapeutic approaches.
Asunto(s)
Epigénesis Genética , Genes Supresores de Tumor , Proteínas/genética , Neoplasias de la Retina/genética , Retinoblastoma/genética , Azacitidina/análogos & derivados , Azacitidina/farmacología , Secuencia de Bases , Western Blotting , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Metilación de ADN/efectos de los fármacos , Análisis Mutacional de ADN , Cartilla de ADN , Decitabina , Regulación Neoplásica de la Expresión Génica , Humanos , Inmunohistoquímica , Datos de Secuencia Molecular , Proteína p130 Similar a la del RetinoblastomaRESUMEN
Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy are caused in most cases by deletions of the DMD gene. These rearrangements are detectable in affected boys and men by a simple multiplex polymerase chain reaction approach. However, this technique is not able to disclose DMD deletions in heterozygous female carriers, and different approaches must be used in these cases. Here, we describe an approach based on the combined use of primed in situ labeling and fluorescence in situ hybridization techniques for the detection of single DMD exons in fixed metaphase chromosomes and interphase nuclei of both male and female subjects, suggesting the usefulness of this tool in the detection of small intragenic deletions of the DMD gene.
Asunto(s)
Distrofina/análisis , Distrofina/genética , Hibridación Fluorescente in Situ/métodos , Etiquetado in Situ Primed/métodos , Cromosomas Humanos/genética , Exones/genética , Femenino , Humanos , Masculino , Metafase/genéticaRESUMEN
Mechanisms underlying multidrug resistance (MDR), one of the major causes of cancer treatment failure, are still poorly understood. We selected the osteosarcoma MDR HosDXR150 cell line by culturing Hos cells in the presence of increasing doxorubicin doses and showed that it is crossresistant to vinblastine. Similarly to the Hos parental cell line, HosDXR150 cells present mutated p53, functionally inactivated pRb/p105 and wild-type pRb2/p130. Owing to p53 mutation, MDR-1 gene, codifying for P-glycoprotein, is upregulated. Evasion of apoptosis in HosDXR150 cells is only partially explained by drug extrusion because of P-glycoprotein overexpression. Analysis of gene expression level profiles showed that parental cell line undergoes apoptosis through an E2F1/p73-dependent pathway while its resistant variant evades it. This result can be explained by the presence of distinct E2Fs-pRb2/p130 complexes on the p73 promoter. Namely, in Hos p73 transcription is activated by E2F1-Rb2/p130-p300 complexes, while in HosDXR150 it is kept repressed by E2F4-Rb2/p130-HDAC1 complexes.
Asunto(s)
Apoptosis , Neoplasias Óseas/metabolismo , Proteínas de Ciclo Celular , Proteínas de Unión al ADN/metabolismo , Proteínas Nucleares/metabolismo , Osteosarcoma/metabolismo , Fosfoproteínas/metabolismo , Proteínas , Factores de Transcripción/metabolismo , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/efectos de los fármacos , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Neoplasias Óseas/tratamiento farmacológico , Neoplasias Óseas/patología , Proteínas de Unión al ADN/genética , Doxorrubicina/farmacología , Resistencia a Múltiples Medicamentos/genética , Resistencia a Antineoplásicos/genética , Factores de Transcripción E2F , Factor de Transcripción E2F1 , Factor de Transcripción E2F4 , Perfilación de la Expresión Génica , Genes Supresores de Tumor , Humanos , Sustancias Macromoleculares , Mutación , Proteínas Nucleares/genética , Osteosarcoma/tratamiento farmacológico , Osteosarcoma/patología , Fosfoproteínas/genética , Regiones Promotoras Genéticas , Proteína p130 Similar a la del Retinoblastoma , Factores de Transcripción/genética , Células Tumorales Cultivadas , Proteína Tumoral p73 , Proteína p53 Supresora de Tumor/genética , Proteínas Supresoras de Tumor , Vinblastina/farmacologíaRESUMEN
Understanding the molecular mechanisms underlying multi-drug resistance (MDR) is one of the major challenges in current cancer research. A phenomenon which is common to both intrinsic and acquired resistance, is the aberrant alteration of gene expression in drug-resistant cancers. Although such dysregulation depends on many possible causes, an epigenetic characterization is considered a main driver. Recent studies have suggested a direct role for epigenetic inactivation of genes in determining tumor chemo-sensitivity. We investigated the effects of the inhibition of DNA methyltransferase (DNMT) and hystone deacethylase (HDAC), considered to reverse the epigenetic aberrations and lead to the re-expression of de novo methylated genes in MDR osteosarcoma (OS) cells. Based on our analysis of the HosDXR150 cell line, we found that in order to reduce cell proliferation, co-treatment of MDR OS cells with DNMT (5-Aza-dC, DAC) and HDAC (Trichostatin A, TSA) inhibitors is more effective than relying on each treatment alone. In re-expressing epigenetically silenced genes induced by treatments, a very specific regulation takes place which suggests that methylation and de-acetylation have occurred either separately or simultaneously to determine MDR OS phenotype. In particular, functional relationships have been reported after measuring differential gene expression, indicating that MDR OS cells acquired growth and survival advantage by simultaneous epigenetic inactivation of both multiple p53-independent apoptotic signals and osteoblast differentiation pathways. Furthermore, co-treatment results more efficient in inducing the re-expression of some main pathways according to the computed enrichment, thus emphasizing its potential towards representing an effective therapeutic option for MDR OS.
Asunto(s)
Antineoplásicos/farmacología , Neoplasias Óseas/metabolismo , Metilasas de Modificación del ADN/antagonistas & inhibidores , Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Inhibidores de Histona Desacetilasas/farmacología , Histona Desacetilasas/metabolismo , Osteosarcoma/metabolismo , Neoplasias Óseas/genética , Línea Celular Tumoral , Biología Computacional , Relación Dosis-Respuesta a Droga , Doxorrubicina/farmacología , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Osteosarcoma/genética , Reproducibilidad de los Resultados , Transducción de Señal , Factores de TiempoRESUMEN
Successful treatment of cancer requires a clear understanding of drug-resistance mechanism. Cancer patient are often treated with standard protocols without considering individual difference in chemosensitivity, whereas the efficacy of anticancer drug varies widely among individual patients. Since chemosensitivity involves multiple interacting factors, it is not sufficient to investigate a single gene or factor to fix chemoresistance. Along with affecting disease progression, the synergism between genetic and epigenetic abnormalities can contribute to convert a sensible tumor cell in a resistant one. Unlike genetic changes, epigenetic changes are potentially reversible. Therefore, treatment with DNA methylation inhibitors can reactivate the expression of genes improperly methylated and can reverse many aspect of cancer phenotype such as drug resistance. The demethylating agents are used in the treatment of several kind of tumor, but toxicity and the potential outcome on the normal methylation patterns have always been concern of researchers and clinicals. It is necessary to create individual chemosensitivity-chemoresistance maps in order to identify the combination of drugs for optimized treatments. An overview on genetic and epigenetic events contributing to clonally selection of chemotherapeutic-resistant tumors is discussed.