RESUMEN
Elevated expression of chemokine receptors in tumors has been reported in many instances and is related to a number of survival advantages for tumor cells including abnormal activation of prosurvival intracellular pathways. In this work we demonstrated an inverse correlation between expression levels of p53 tumor suppressor and CXCR5 chemokine receptor in MCF-7 human breast cancer cell line. Lentiviral transduction of MCF-7 cells with p53 shRNA led to elevated CXCR5 at both mRNA and protein levels. Functional activity of CXCR5 in p53-knockdown MCF-7 cells was also increased as shown by activation of target gene expression and chemotaxis in response to B-lymphocyte chemoattractant CXCL13. Using deletion analysis and site-directed mutagenesis of the cxcr5 gene promoter and enhancer elements, we demonstrated that p53 appears to act upon cxcr5 promoter indirectly, by repressing the activity of NFκB transcription factors. Using chromatin immunoprecipitation and reporter gene analysis, we further demonstrated that p65/RelA was able to bind the cxcr5 promoter in p53-dependent manner and to directly transactivate it when overexpressed. Through the described mechanism, elevated CXCR5 expression may contribute to abnormal cell survival and migration in breast tumors that lack functional p53.
Asunto(s)
Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Regulación Neoplásica de la Expresión Génica , Receptores CXCR5/genética , Proteína p53 Supresora de Tumor/metabolismo , Quimiocina CXCL13/metabolismo , Quimiotaxis/genética , Quimiotaxis/inmunología , Biología Computacional , Elementos de Facilitación Genéticos , Femenino , Técnicas de Silenciamiento del Gen , Humanos , Células MCF-7 , FN-kappa B/metabolismo , Regiones Promotoras Genéticas , Unión Proteica , Receptores CXCR5/metabolismo , Elementos de Respuesta , Transducción de Señal , Activación Transcripcional , Proteína p53 Supresora de Tumor/genéticaRESUMEN
The second stage of labor is a dynamic event that may require assistance when maternal efforts fail to effect delivery or when there are nonreassuring fetal heart tones. Therefore, knowing how to perform an operative vaginal delivery with forceps or vacuum is vital for family physicians who provide maternity care. Vacuum is rapidly replacing forceps as the predominant instrument, but each has advantages and disadvantages, including increased risk of maternal trauma with forceps and increased risk of neonatal cephalohematoma with vacuum. Use of a second instrument if the first one fails is associated with worse outcomes. Routine episiotomy in operative vaginal delivery is no longer recommended. The "ABCDEFGHIJ" mnemonic can facilitate proper use and application of the vacuum device and minimize risks, and practicing the techniques on mannequins can provide an introduction to the skills of operative vaginal delivery.