Increased MDM2 expression is associated with inferior survival in mantle cell lymphoma, but not related to the MDM2 SNP309

We here show that increased expression of MDM2, a negative regulator of p53, correlates with inferior survival in a series of 43 mantle cell lymphomas. MDM2 overexpression is associated with copy number gains of the MDM2 locus in single tumors, but not with the recently reported MDM2 promoter SNP309

Frequent polymorphic changes but not mutations of TRAIL receptors DR4 and DR5 in mantle cell lymphoma and other B-cell lymphoid neoplasms

Background and objectives: tumor necrosis factor related apoptosis-inducing ligand (TRAIL) receptors DR4 and DR5 have been mapped to chromosome 8p21-22, a region frequently deleted in different lymphoid neoplasms. Design and methods: to investigate the potential alterations of these genes in lymphoid neoplasms, we examined the presence of gene mutations in exons 3, 4, and 9 in 69 cases with mantle cell lymphoma (MCL), 16 with chronic lymphocytic leukemia (CLL), 12 with follicular lymphomas (FL) and 17 with large B-cell-lymphomas (DLBCL), as well as in 4 lymphoid cell lines carrying the t(11;14) translocation, and 91 healthy blood donors. Results: three CLL and three MCL cases had 8p deletions. Two nucleotide changes in or near the intron 3 splice consensus sequence and a silent change were found. These rare changes were also present in the germ-line of the patients. The DR4 death domain A1322G polymorphism was significantly more frequent in MCL [odds ratio (OR) = 5.9; 95% confidence interval (CI), 1.92-18.1] and CLL (OR = 4.5; CI, 1.18-17) patients than in a sex and age-adjusted healthy population. In contrast, the DR4 exon 4 C626G polymorphism was associated with a significant overall decreased risk for MCL (OR = 0.3; CI, 0.12-0.8). No mutations or cancer-associated polymorphic changes were found in DR5 domains. Interpretation and conclusions: these findings indicate that mutations of DR4 and DR5 are uncommon in lymphoid neoplasms but DR4 polymorphic alleles may contribute to the pathogenesis of these malignancies

Identification of Methylated Genes Associated with Aggressive Clinicopathological Features in Mantle Cell Lymphoma

Background: Mantle cell lymphoma (MCL) is genetically characterized by the t(11;14)(q13;q32) translocation and a high number of secondary chromosomal alterations. The contribution of DNA methylation to MCL lymphomagenesis is not well known. We sought to identify epigenetically silenced genes in these tumours that might have clinical relevance. Methodology/Principal Findings: To identify potential methylated genes in MCL we initially investigated seven MCL cell lines treated with epigenetic drugs and gene expression microarray profiling. The methylation status of selected candidate genes was validated by a quantitative assay and subsequently analyzed in a series of primary MCL (n=38). After pharmacological reversion we identified 252 potentially methylated genes. The methylation analysis of a subset of these genes (n=25) in the MCL cell lines and normal B lymphocytes confirmed that 80% of them were methylated in the cell lines but not in normal lymphocytes. The subsequent analysis in primary MCL identified five genes (SOX9,HOXA9,AHR,NR2F2 ,and ROBO1) frequently methylated in these tumours. The gene methylation events tended to occur in the same primary neoplasms and correlated with higher proliferation, increased number of chromosomal abnormalities, and shorter survival of the patients. Conclusions: We have identified a set of genes whose methylation degree and gene expression levels correlate with aggressive clinicopathological features of MCL. Our findings also suggest that a subset of MCL might show a CpG island methylator phenotype (CIMP) that may influence the behaviour of the tumours

Improved classification of leukemic B-cell lymphoproliferative disorders using a transcriptional and genetic classifier

B-cell chronic lymphoproliferative disorders (B-CLPD) encompass a group of hematologic tumors that often present with leukemic involvement.1 Their heterogeneity and the lack of relatively specific diagnostic markers for most of these diseases make their diagnosis challenging, especially in cases that only have blood involvement or when histology is not available. With the currently used immunophenotypic and molecular markers, around 10% of B-CLPD cases remain unclassifiable and are categorized as B-CLPD, not otherwise specified (B-CLPD, NOS)

Anàlisi dels mecanismes moleculars implicats en el desenvolupament i progressió dels limfomes de cèl·lula B petita

INTRODUCCIÓ: Les neoplàsies limfoides agrupen un conjunt de malalties que, tot i compartir certes característiques comunes, presenten una gran heterogeneïtat en la seva biologia i manifestacions clíniques. En la present tesi s´han estudiat els mecanismes moleculars implicats en el desenvolupament i progressió de diferents entitats que s´inclouen dins del grup dels Limfomes No-Hodgkin de cèl·lula B (NHL, de l´anglès Non-Hodgkin Lymphoma), especialment el limfoma de cèl·lules del mantell (MCL, de l´anglès Mantle Cell Lymphoma) i la leucèmia limfàtica crònica (CLL, de l´anglès Chronic Lymphocytic Leukemia), els quals són limfomes de cèl·lula B petita. MATERIAL I MÈTODES: En aquest treball s´han emprat una gran diversitat de tècniques experimentals, de les que destaquen la hibridació genòmica comparada (CGH, de l´anglès Comparative Genomic Hybridization) per estudiar les alteracions cromosòmiques dels tumors, la reacció en cadena de la polimerasa (PCR, de l´anglès Polymerase Chain Reaction) i la cromatografia líquida desnaturalitzant (DHPLC, de l´anglès Denaturing High Perfomance Liquid Chromatography) per determinar l´adquisició d´alteracions en el material genètic a nivell de DNA; així com la PCR quantitativa a temps real (qPCR) i la realització de microarrays d´oligonucleòtids d´alta densitat per analitzar l´expressió gènica a nivell de mRNA.RESULTATS I CONCLUSIONS: L´estudi de gens implicats en la proliferació de MCL ha permès la construcció d´un model predictor de la supervivència dels pacients basat en l´expressió dels cinc gens RAN, MYC, TNFRSF10B, POLE2 i SLC29A2. Aquest model es pot aplicar tant en material congelat com en teixits biològics fixats amb formol i inclosos en parafina (FFPE, de l´anglès Formalin-Fixed and Paraffin-Embedded tissue), podent ésser útil en la presa de decisions terapèutiques1. També s´ha estudiat el gen MDM2, implicat en les vies de resposta al dany del DNA. S´ha observat que, a part de les alteracions del gen p53, l´augment de l´expressió gènica de MDM2 es correlaciona directament amb una disminució de la supervivència en MCL. En alguns casos aquest augment de l´expressió pot donar-se per guany del locus genòmic del gen, mentre que la presència del SNP309 al seu promotor no es relaciona amb els canvis d´expressió (2).La desregulació dels mecanismes implicats en la mort cel·lular programada o apoptosi també juga un paper clau en els processos de tumorogènesi. S´ha observat que els receptors de mort TNFRSF10A i TNFRSF10B es troben poc mutats en neoplàsies limfoides, indicant que la seva alteració no és rellevant per explicar la resistència a l´apoptosi observada en aquests tipus de limfomes. Tot i això, la presència del polimorfisme A1322G al domini de mort de TNFRSF10A s´associa amb un augment de risc a patir MCL i CLL; mentre que la presència del polimorfisme C626G al domini d´unió a lligand de TNFRSF10A sembla jugar un paper protector en MCL; suggerint un possible paper de dits polimorfismes en la resistència a la mort mediada per TRAIL (3).Finalment, l´estudi global de les alteracions que participen en els fenòmens de progressió clínica primerenca de la CLL ha permès determinar la modulació de l´expressió d´un petit grup de gens (58) que participen en diferents vies cel·lulars. Destaca un subconjunt de gens que actuen en la inhibició de l´adhesió i motilitats cel·lulars, els quals presenten una disminució de la seva expressió. També s´ha observat que la progressió clínica de les CLL s´associa, en alguns casos, amb la inactivació de certs gens supressors de tumors. Per altra banda, l´evolució primerenca d´aquest tips de leucèmia sembla implicar poca inestabilitat cromosòmica (4).ARTICLES GENERATS PER LA PRESENT TESI:(1). Hartmann E, Fernandez V, Moreno V, Valls J, Hernandez L, Bosch F, Müller-Hermelink HK, Ott G, Rosenwald A, Campo E. A five-gene model to predict survival in mantle cell lymphoma and its application to formalin-fixed paraffin-embedded tissue. J Clin Oncol, under revision (Journal impact factor 2006: 13.598).(2). Hartmann E, Fernandez V, Stoecklein H, Hernández L, Campo E, Rosenwald A. Increased MDM2 expression is associated with inferior survival in mantle cell lymphoma, but not related to the MDM2 SNP309, Haematologica, 92:574-575 (Journal impact factor 2006: 5.032).(3). Fernandez V, Jares P, Bea S, Salaverria I, Guino E, de Sanjose S, Colomer D, Ott G, Montserrat E, Campo E. Frequent polymorphic changes but not mutations of TRAIL receptors DR4 and DR5 in mantle cell lymphoma and other B-cell lymphoid neoplasms. Haematologica. 2004 Nov;89(11):1322-31 (Journal impact factor 2006: 5.032).(4). Fernandez V, Jares P, Salaverria I, Giné E, Beà S, Aymerich M, Colomer D, Villamor N, Bosch F, Montserrat E, Campo E. Gene expression profile and genomic changes in disease progression of early-stage chronic lymphocytic leukemia. Haematologica, accepted (Journal impact factor 2006: 5.032)."ANALYSIS OF THE MOLECULAR MECHANISMS IMPLIED IN THE DEVELOPMENT AND PROGRESSION OF SMALL B CELL LYMPHOMAS" INTRODUCTION:Different molecular mechanisms implied in the development and progression of distinct subtypes of small B cell lymphomas that belong to Non-Hodgkin´s Lymphomas (NHL) have been studied in the present work, specially focusing on Mantle Cell Lymphoma (MCL) and Chronic Lymphocytic Leukemia (CLL).MATERIALS AND METHODS:Comparative genomic hybridization (CGH) has been aplied to study the chromosomal alterations of the tumors. Polymerase chain reaction (PCR) and denaturing high performance liquid chromatography (DHPLC) techniques have been performed to detect nucleotide alterations in certain genes; whereas real time quantitative PCR (qPCR) and high density oligonucleotide microarrays have been used to analyse gene expression.RESULTS AND DISCUSSION:The gene expression model composed of the five genes RAN, MYC, TNFRSF10B, POLE2 and SLC29A2 allows the survival prediction of MCL patients with widely disparate clinical outcome and is superior to the immunohistochemical marker Ki-67. The predictor is applicable to fresh frozen and formalin-fixed paraffin-embedded (FFPE) tumor samples. On the other side, the study of the MDM2 gene has shown that increased gene expression correlates with inferior survival in MCL. MDM2 overexpression is associated with copy number gains of the MDM2 locus in single tumors, but not with the recently reported MDM2 promoter SNP309.The study of the death receptors TNFRSF10A and TNFRSF10B has shown that mutations in these genes are uncommon in lymphoid neoplasms, but the presence of certain TNFRSF10A polymorphisms (A1322G in the death domain and C626G in the extracellular binding domain) can contribute to the pathogenesis of these malignancies. The study of early clinical progression in CLL has allowed the identification of a significant modulation of the gene expression of 58 genes, with a particular downregulation of genes that are inhibitors of cell adhesion and motility. On the other side, our results indicate that clinical progression of early stage CLL is associated with karyotype evolution and inactivation of certain tumor suppressor genes. </i