EVALUACIÓN DE LA REGULACIÓN TRANSCRIPCIONAL DEL GEN MULTIRESISTENCIA A FÁRMACOS (MDR1) POR EL FACTOR DE TRANSCRIPCIÓN YINYANG 1 (YY1) EN LA LEUCEMIA LINFOBLÁSTICA AGUDA INFANTIL

Abstract

Introduction. In our country, acute lymphoblastic leukemia (ALL) is the leading cause of childhood cancer, about 30% of patients do not respond to conventional treatments and do not survive. One of the most studied mechanisms is mediated resistance protein multiple drugs resistance 1 (MDR1). Previously we determined that the mdr1 gene promoter has 4 binding sites for transcription factor Ying Yang 1 (YY1), has shown that its over-activation in tumor cells provides a mechanism of resistance to apoptosis, This suggests that might be involved in the transcriptional regulation of mdr1. Objective. Assess the transcriptional regulation of the mdr1 gene by transcription factor YY1, expression at different stages of chemotherapy and their correlation with prognostic factors of treatment response in ALL. Methods. Promoter region was cloned gene mdr1, in the reporter plasmid PGL3, were mutated each of the binding sites for YY1, and transfected cell line PC3 to evaluate the activity of the luciferase reporter gene. Chip was performed in the cell line RS4;11 using an antibody specific for YY1, and assessed for binding to each of the sites, by PCR amplification of the segments immunoprecipitates. Was determined by immunocytochemistry the expression of MDR1 and YY1 in peripheral blood mononuclear cells of 88 pediatric ALL patients and 53 control subjects. We quantified the percentage of positive cells and intensity of expression of both proteins in the diagnosis, and end of the different stages of treatment, and evaluated their correlation with risk factors that determine the potential response to chemotherapy. Results. The mdr1 promoter activity shows a significant decrease of the reporter gene, 4 mutations in the YY1 sites, Chip through YY1 demonstrated that joins the four sites in the promoter region. It was found that expression of YY1 and MDR1 is increased in mononuclear cells from patients with ALL compared to normal subjects and this expression is directly proportional. On the other hand, it was determined that patients with L1 subtype (morphologic subtype less aggressive) presents a lower expression compared with patients with ALL L2. Also observed increased expression of both proteins in male patients. Conclusions. Is demonstrated for the first time adjusted so that YY1 transcriptional the mdr1 gene. This correlates with the increased expression of YY1 and MDR1 in ALL patients compared to control subjects and this expression is increased after chemotherapy. Increased expression correlates directly with risk factors of poor response to treatment, such as morphologic subtype and gender.