Estudio del gen WT1 en la leucemia mieloblástica aguda

En los últimos años se ha producido un notable progreso en la elucidación de la patogénesis molecular de las Leucemias Mieloblásticas Agudas (LMA). Sin embargo, la mayoría de las alteraciones genéticas que subyacen en esta patología son todavía desconocidas. La LMA se caracteriza por la presencia de un “stop madurativo” de las células de la línea mieloide, que escapan de la inhibición de las señales anti-proliferativas y adquieren una capacidad indefinida de auto-renovación. Los posibles mecanismos que pueden explicar el crecimiento incontrolado de las células cancerígenas son la pérdida de función de los genes supresores de tumores y/o la activación de los oncogenes. Aunque ambas son funciones opuestas que en principio deberían ser mutuamente excluyentes en una misma proteína, existen evidencias de que una misma proteína puede mostrar ambas funciones bajo condiciones celulares diferentes. Un ejemplo de ello es el gen del tumor de Wilms (WT1), el cual presenta este tipo de comportamiento dual dependiendo del tipo celular donde se está expresando. El gen WT1 fue originariamente definido como un gen supresor tumoral al encontrarse mutado en un 15% de los tumores de Wilms. Sin embargo, el estudio del papel de WT1 en las células cancerígenas ha revelado un inesperado papel como oncogén. La mayoría de estudios se ha realizado en casos de leucemia donde se ha demostrado la importancia biológica y clínica de WT1 en la supervivencia, diferenciación y proliferación celular. En la presente tesis se ha estudiado a un total de 274 pacientes diagnosticados de LMA de novo en un sólo centro para analizar en profundidad el papel de la expresión total de WT1, la expresión de sus 4 isoformas principales, las variaciones genéticas del gen, tanto mutaciones como el polimorfismo SNP rs16754 y la expresión de los miRNA que podrían estar involucrados en la regulación epigenética de WT1, con el objetivo de elucidar el papel de WT1 en la leucemogénesis. Los resultados de esta tesis muestran una expresión de WT1 total mayor en la leucemia en comparación con su contrapartida sana de células CD34+ de sangre de cordón umbilical, que, además, parece conferir una peor supervivencia a los pacientes que pertenecen al subgrupo FAB M0. En cuanto a las cuatro isoformas principales de WT1, los resultados de esta tesis parecen sugerir que dicha sobreexpresión de WT1 total pueda ser debida a un aumento en la expresión de las isoformas A, B y/o C junto a una disminución relativa de la isoforma D. Además, la mejor supervivencia observada en los pacientes que sobreexpresan la isoforma D hace presuponer que dicha isoforma pueda tener un papel protector en la LMA, aunque este resultado debería ser confirmado con futuros estudios funcionales. Tras el cribado de alteraciones genéticas de WT1 por High Resolution Melting, se encontró la presencia de un 30% de pacientes con la presencia del SNP rs16754 de WT1 en heterocigosis, consistente con lo esperable en la población caucásica. La presencia del alelo menor de dicho SNP no mostró diferencias significativas en términos de supervivencia. Además se detectaron mutaciones del gen WT1 en el 4% de la serie de pacientes, asociándose con un valor pronóstico desfavorable independiente en la serie global. Para averiguar los posible microRNAs potencialmente implicados en la regulación epigenética de WT1 se hibridaron chips de arrrays de miRNA en 10 muestras de pacientes seleccionados en función de su expresión de WT1 total, encontrándose 9 miRNAs con expresión diferencial que fueron validados mediante PCR cuantitativa en la serie de pacientes y controles. Los resultados de la validación sugieren que algunos de los microRNAs estudiados presentan patrones de expresión diferentes a la normalidad pudiendo estar implicados en la regulación de la diferenciación celular. Además, se observó una mejor supervivencia para la infraexpresión de los miR-223, miR-425, miR-500 y miR-1307 en la serie global, aunque no se pudo demostrar su valor pronóstico independiente.In recent years there has been considerable progress in the elucidation of the molecular pathogenesis of the acute Myeloblastic leukemia (AML). However, most of the genetic changes that underlie this disease are still unknown. The AML is characterized by the presence of a maturation stop of the myeloid cell line that escapes from inhibition of anti-proliferative signals and acquire an indefinite self-renewal capacity. The possible mechanisms that may explain the uncontrolled cancer cells growth are the loss of function of the tumor suppressor genes and the activation of oncogenes. Although both are opposing functions that should be mutually exclusive in the same protein, there is evidence that a same protein may show both functions under different cellular conditions. An example of this is the Wilms tumor 1 gene (WT1), presenting this double behavior depending on the cell type where it's expressed. The WT1 gene was originally defined as a suppressor tumor gene based on mutations found in 15% of Wilms tumors. However, the study of the WT1 gene in cancer cells has revealed an unexpected role as oncogene. Most of the studies were made in leukemia and have shown the biological and clinical importance of WT1 in survival, differentiation and cell proliferation. In the present thesis a total of 274 patients diagnosed with de novo AML in a single center has been studied to analyze in depth the role of the total WT1 expression, the expression of their main 4 isoforms, genetic variations including mutations and the polymorphism rs16754, and expression of miRNA that could potentially be involved in the epigenetic regulation of WT1, in order to clarify the role of WT1 in leukemogenesis. The results of this thesis showed an overexpression of total WT1 in leukemia cells in comparison with its healthy counterpart of CD34 cells from the umbilical cord blood. On the other hand, it seems that it confer a worse survival in patients belonging to FAB M0 subgroup. Referring to the four main WT1 isoforms, the results suggest that such total WT1 overexpression in AML may be due to an increase in the expression of the A, B and C isoforms, together with a relative decrease of isoform D. In addition, the better prognosis observed in patients that over-expressed D isoform presuppose that this isoform might have a protective role in AML, although this result should be confirmed with further functional studies. After the screening of genetic variations of WT1 with the High Resolution Melting tool, the presence of the SNP rs16754 of WT1 in heterozygosis was found in 30% of the patients, consistent with the expected frequency in the Caucasian population. The presence of the minor allele genotype of the SNP (WT1AG) showed no significant difference in terms of survival. In addition, mutations in the WT1 gene were detected in 4% of the series and were associated with an unfavorable prognosis in the multivariate analysis. To find out the microRNAs potentially involved in the epigenetic regulation of WT1, 10 samples of patients selected on the basis of the total WT1 expression (5 with over-expression and 5 with down-expression) were hybridized with miRNA arrays, showing 9 miRNAs with differential expression that were validated by quantitative PCR in patients and controls samples. The validation results suggested that some of the studied microRNAs had different expression patterns and might be involved in the regulation of cell differentiation. On the other hand, an improvement in survival was found for the down-expression of miR-223, miR-425, miR-500 and miR-1307 in the univariate analysis, although its independent prognostic value could not be demonstrated

CYP2C8 gene polymorphism and bisphosphonate-related osteonecrosis of the jaw in patients with multiple myeloma

Osteonecrosis of the jaw is an uncommon but potentially serious complication of bisphosphonate therapy in multiple myeloma. Previous studies showed that the presence of one or two minor alleles of the cytochrome P450, subfamily 2C polypeptide 8 gene (CYP2C8) polymorphism rs1934951 was an independent prognostic marker associated with development of osteonecrosis of the jaw in multiple myeloma patients treated with bisphosphonates. The aim of this study was to validate the frequency of SNP rs193451 in 79 patients with multiple myeloma. In 9 (22%) patients developing osteonecrosis of the jaw, a heterozygous genotype was found, in contrast with those who did not develop osteonecrosis of the jaw (n=4, 11%) or healthy individuals (n=6, 13%). We found no differences in the cumulative risk of developing osteonecrosis of the jaw between patients homozygous and heterozygous for the major allele. We were unable to confirm a significant association between this polymorphism and the risk of developing osteonecrosis of the jaw

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The second-order Fourier coefficients (v(2)) characterizing the azimuthal distributions of Y(1S) and Y(2S) mesons produced in PbPb collisions at root s(NN) = 5.02 TeV are studied. The Y mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb(-1). The scalar product method is used to extract the v2 coefficients of the azimuthal distributions. Results are reported for the rapidity range vertical bar y vertical bar < 2.4, in the transverse momentum interval 0 < pT < 50 GeV/c, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/psi mesons, the measured v(2) values for the Y mesons are found to be consistent with zero. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe