RESUMEN
Ovarian cancer survival rates have stagnated in the last 20 years despite the development of novel chemotherapeutic agents. Modulators of gene expression, such as histone deacetylase (HDAC) inhibitors, are among the new agents being used in clinical trials. Predictors of sensitivity to chemotherapy have remained elusive. In this study, we show that the expression of the transcriptional corepressor C-terminal binding protein-2 (CtBP2) is elevated in human ovarian tumors. Downregulation of CtBP2 expression in ovarian cancer cell lines using short-hairpin RNA strategy suppressed the growth rate and migration of the resultant cancer cells. The knockdown cell lines also showed upregulation of HDAC activity and increased sensitivity to selected HDAC inhibitors. Conversely, forced expression of wild-type CtBP2 in the knockdown cell lines reversed HDAC activity and partially rescued cellular sensitivity to the HDAC inhibitors. We propose that CtBP2 is an ovarian cancer oncogene that regulates gene expression program by modulating HDAC activity. CtBP2 expression may be a surrogate indicator of cellular sensitivity to HDAC inhibitors.
Asunto(s)
Oxidorreductasas de Alcohol/metabolismo , Resistencia a Antineoplásicos/fisiología , Regulación Neoplásica de la Expresión Génica/fisiología , Histona Desacetilasas/metabolismo , Neoplasias Glandulares y Epiteliales/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neoplasias Ováricas/metabolismo , Oxidorreductasas de Alcohol/genética , Antineoplásicos/farmacología , Western Blotting , Carcinoma Epitelial de Ovario , Proteínas Co-Represoras , Femenino , Técnicas de Silenciamiento del Gen , Inhibidores de Histona Desacetilasas/farmacología , Histona Desacetilasas/genética , Humanos , Inmunohistoquímica , Neoplasias Glandulares y Epiteliales/genética , Proteínas del Tejido Nervioso/genética , Oncogenes , Neoplasias Ováricas/genéticaRESUMEN
The objective of this study was to examine placentas after delivery from normal, healthy patients at term gestation. The placentas were from elective cesarean sections (n = 10, prior to the onset of labor) and spontaneous vaginal delivery (n = 10, after labor). We found that deoxyribonucleic acid laddering was present in all placentas and consistent with the pattern found in tissues that undergo apoptosis. Paraffin-embedded sections of placental villi stained by the in situ terminal deoxynucleotidyl transferase mediated biotinylated dUTP nick end labeling method revealed positive apoptotic nuclei in the placental villi. Reverse-transcriptase polymerase chain reaction demonstrated expression of messenger RNA for testosterone-repressed prostate message 2 and B cell lymphoma/leukemia-2 in the placenta. Our data demonstrate that apoptosis occurs in human term placenta.
Asunto(s)
Apoptosis , Chaperonas Moleculares , Placenta/citología , Cesárea , Clusterina , Fragmentación del ADN , Femenino , Edad Gestacional , Glicoproteínas/genética , Humanos , Etiquetado Corte-Fin in Situ , Trabajo de Parto , Placenta/química , Embarazo , Proteínas Proto-Oncogénicas c-bcl-2/genética , ARN Mensajero/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Eukaryotic DNA topoisomerase III was first identified by studying the hyper-recombination and slow growth phenotypes of yeast mutants. Topoisomerase III interacts with DNA helicase SGS1 and the two proteins are involved in DNA recombination, cellular aging and maintenance of genome stability. A human homolog of topoisomerase III has previously been identified. Here we report the identification of cDNAs and the determination of gene structure for a second human topoisomerase III gene. This novel gene expresses three alternatively spliced transcripts, which encode gene products different in the putative DNA-binding C-termini. The largest gene product of the novel topoisomerase III was expressed and shown to interact with SGS1 protein and partially rescue the slow growth defect of a yeast topoisomerase III mutant. The presence of more than one human topoisomerase III is reminiscent of mammalian topoisomerase II, which has two genetically distinct isoforms with different expression patterns and probably different functions in mammalian cells.