RESUMO
Purpose Dysregulated microRNAs are implicated in the pathogenesis and aggressiveness of acute myeloid leukemia (AML). We describe the effect of the hematopoietic stem-cell self-renewal regulating miR-193b on progression and prognosis of AML. Methods We profiled miR-193b-5p/3p expression in cytogenetically and clinically characterized de novo pediatric AML (n = 161) via quantitative real-time polymerase chain reaction and validated our findings in an independent cohort of 187 adult patients. We investigated the tumor suppressive function of miR-193b in human AML blasts, patient-derived xenografts, and miR-193b knockout mice in vitro and in vivo. Results miR-193b exerted important, endogenous, tumor-suppressive functions on the hematopoietic system. miR-193b-3p was downregulated in several cytogenetically defined subgroups of pediatric and adult AML, and low expression served as an independent indicator for poor prognosis in pediatric AML (risk ratio ± standard error, -0.56 ± 0.23; P = .016). miR-193b-3p expression improved the prognostic value of the European LeukemiaNet risk-group stratification or a 17-gene leukemic stemness score. In knockout mice, loss of miR-193b cooperated with Hoxa9/Meis1 during leukemogenesis, whereas restoring miR-193b expression impaired leukemic engraftment. Similarly, expression of miR-193b in AML blasts from patients diminished leukemic growth in vitro and in mouse xenografts. Mechanistically, miR-193b induced apoptosis and a G1/S-phase block in various human AML subgroups by targeting multiple factors of the KIT-RAS-RAF-MEK-ERK (MAPK) signaling cascade and the downstream cell cycle regulator CCND1. Conclusion The tumor-suppressive function is independent of patient age or genetics; therefore, restoring miR-193b would assure high antileukemic efficacy by blocking the entire MAPK signaling cascade while preventing the emergence of resistance mechanisms.
Assuntos
Leucemia Mieloide Aguda/genética , MicroRNAs/biossíntese , Animais , Processos de Crescimento Celular/genética , Regulação para Baixo , Genes Supressores de Tumor , Xenoenxertos , Proteínas de Homeodomínio/genética , Humanos , Leucemia Mieloide Aguda/patologia , Leucemia Mieloide Aguda/terapia , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , MicroRNAs/genética , Proteína Meis1/genética , PrognósticoRESUMO
Mesenchymal stromal cell (MSCs) are key cellular components for site-specific tissue regeneration. The chemokine stromal derived factor 1 alpha (SDF-1α) is known to attract stem cells via the C-X-C chemokine receptor-4 (CXCR4) receptor. The aim of the study was to develop a model for stem cell attraction using SDF-1α overexpressing fat tissue grafts. Murine MSCs were lentiviral transduced to express the genes for enhanced green fluorescent protein, firefly luciferace, and human CXCR4 (hCXCR4). Murine fat tissue was adenoviral transduced to express SDF-1α and red fluorescent protein transgenes. MSCs were cultured on transwells with SDF-1α containing supernatants from transduced fat tissue. The numbers of migrated MSCs in four groups (with hCXCR4 positive (+) or hCXCR4 negative (-) MSCs with or without SDF-1α containing supernatant) were investigated. After 36 h of culture, 9025 ± 925 cells migrated through the membrane of the transwells in group 1 (CXCR4+/SDF-1α+), 4817 ± 940 cells in group 2 (CXCR4-/SDF-1α+), 2050 ± 766 cells in group 3 (CXCR4+/SDF-1α-), and 2108 ± 426 cells in group 4 (CXCR4-/SDF-1α-). Both, the presence of SDF-1α and the expression of hCXCR4 significantly increased the migration rates (p < 0.0001). MSCs overexpressing the CXCR4 receptor by lentiviral transduction are highly attracted by medium from SDF-1α expressing fat tissue in vitro. Thus, SDF-1α activated tissue grafts may be a strategy to enhance site-specific musculoskeletal tissue regeneration.