Search

Background MicroRNAs are known to inhibit gene expression by binding to the 3′UTR of the target transcript. Downregulation of miR-223 has been recently reported to have prognostic significance in CLL. However, there is no evidence of the pathogenetic mechanism of this miRNA in CLL patients. Methods By applying next-generation sequencing techniques we have detected a common polymorphism (rs2307842), in 24% of CLL patients, which disrupts the binding site for miR-223 in HSP90B1 3′UTR. We investigated whether miR-223 directly targets HSP90B1 through luciferase assays and ectopic expression of miR-223. Quantitative real-time polymerase chain reaction and western blot were used to determine HSP90B1 expression in CLL patients. The relationship between rs2307842 status,HSP90B1 expression and clinico-biological data were assessed. Results HSP90B1 is a direct target for miR-223 by interaction with the putative miR-223 binding site. The analysis in paired samples (CD19+ fraction cell and non-CD19+ fraction cell) showed that the presence of rs2307842 and IGHV unmutated genes determined HSP90B1 overexpression in B lymphocytes from CLL patients. These results were confirmed at the protein level by western blot. Of note, HSP90B1 overexpression was independently predictive of shorter time to the first therapy in CLL patients. By contrast, the presence of rs2307842 was not related to the outcome. Conclusions HSP90B1 is a direct target gene of miR-223. Our results provide a plausible explanation of why CLL patients harboring miR-223 downregulation are associated with a poor outcome, pointing out HSP90B1 as a new pathogenic mechanism in CLL and a promising therapeutic target. Keywords Chronic lymphocytic leukemia MicroRNAs Next-generation sequencing, European Commision (EC). Funding FP7/SP1/HEALTH. Project Code: 306242

Tesis por compendio de publicaciones, [ES]La presente tesis doctoral tiene como objetivos caracterizar el reordenamiento de la cadena pesada de inmunoglobulinas (IGH) en mieloma múltiple, para posteriormente evaluar la presencia de enfermedad mínima residual (EMR) en muestras de seguimiento de estos pacientes mediante técnicas de secuenciación de nueva generación (NGS). Los principales resultados obtenidos se han agrupado en 3 trabajos que han sido ya publicados en revistas indexadas.

Tesis por compendio de publicaciones, [ES] La macroglobulinemia de Waldenström (MW) es un síndrome linfoproliferativo (SLP) B poco común caracterizado por infiltración de la médula ósea (MO) por células linfoplasmocíticas y producción de una inmunoglobulina (Ig) monoclonal tipo IgM. Forma parte del grupo de enfermedades denominadas gammapatías monoclonales, en el que también se incluyen el mieloma múltiple (MM) y la gammapatía monoclonal de significado incierto (GMSI). Su nombre deriva de Jan Gosta Waldenström, célebre médico sueco que describió por primera vez dos pacientes con hemorragia de la mucosa oral, epistaxis y linfadenopatía generalizada. Las pruebas de laboratorio de estos pacientes revelaron anemia normocrómica, trombocitopenia, elevación de la velocidad de sedimentación globular (VSG) y disminución del fibrinógeno y la albúmina. Waldenström observó dos diferencias cruciales entre esta afección y el MM: en primer lugar, sus pacientes no presentaban ni dolor ni lesiones óseas y, en segundo lugar, la MO estaba infiltrada por células linfocíticas más que plasmocíticas. Las observaciones preliminares de Waldenström se incluyen en los criterios actuales de diagnóstico para la MW, definidos en el panel consenso que se estableció en la 2ª Reunión Internacional de MW (Atenas, 2002). De acuerdo con ellos, la MW se define por la presencia de una IgM monoclonal (pico M) de cualquier grado, junto con afectación de la MO por infiltrado linfoplasmacítico con patrón predominantemente intertrabecular. Debe considerarse como una entidad clinicopatológica distinta y no como un síndrome clínico secundario a la secreción de IgM., [EN] Transformation of Waldenström’s macroglobulinemia (WM) to diffuse large B-cell lymphoma (DLBCL) occurs in up to 10% of patients and is associated with an adverse outcome. Here we performed the first wholeexome sequencing study of WM patients who evolved to DLBCL and report the genetic alterations that may drive this process. Our results demonstrate that transformation depends on the frequency and specificity of acquired variants, rather than on the duration of its evolution. We did not find a common pattern of mutations at diagnosis or transformation; however, there were certain abnormalities, such as MYD88 and CD79B, that were present in a high proportion of clonal tumor cells and that were conserved during this transition, suggesting that they have a key role as early drivers. In addition, recurrent mutations gained in some genes at transformation (e.g., PIM1, FRYL, HNF1B) represent cooperating events in the selection of the clones responsible for disease progression. Detailed comparison reveals the gene abnormalities at diagnosis and transformation to be consistent with a branching model of evolution. Finally, the frequent mutation observed in the CD79B gene in this specific subset of patients implies that it is a potential biomarker predicting transformation in WM.