Whole-genome analysis and HLA genotyping of enteropathy-type T-cell lymphoma reveals 2 distinct lymphoma subtypes

BACKGROUND & AIMS: Enteropathy-type T-cell lymphoma (ETL) is an aggressive extranodal T-cell non-Hodgkin lymphoma assumed to arise in the setting of celiac disease. METHODS: To precisely define the genetic alterations underlying the pathogenesis of ETL, 30 ETL samples were profiled for genetic copy number alterations using high-resolution whole-genome tiling path array comparative genomic hybridization. To investigate the potential association of genetic alterations in ETL with celiac disease, HLA-DQB1 genotyping was performed. RESULTS: By array comparative genomic hybridization, 13 novel recurrent minimal regions of chromosomal alteration were identified on multiple chromosome arms. ETL is characterized by frequent complex gains of 9q31.3-qter (70% of cases), or by an almost mutually exclusive 2.5-megabase loss of 16q12.1 (23% of cases). Two distinct groups of ETL could be delineated morphologically and genetically: type 1 ETL is characterized by nonmonomorphic cytomorphology, CD56 negativity, and chromosomal gains of 1q and 5q. Type 1 ETL also appears to be linked pathogenetically to celiac disease, sharing genetic alterations and HLA-DQB1 genotype patterns with (refractory) celiac disease. Type 2 ETL shows monomorphic small- to medium-sized tumor cell morphology, frequently shows CD56 expression, MYC oncogene locus gain, and rare gains of chromosomes 1q and 5q. In contrast to type 1 ETL, type 2 ETL shows a HLA-DQB1 genotype pattern more resembling that of the normal Caucasian population. CONCLUSIONS: Contrary to current clinical classification, ETL comprises 2 morphologically, clinically, and genetically distinct lymphoma entities. In addition, type 2 ETL may not be associated with celiac disease.     

Transformation of follicular lymphoma to diffuse large B-cell lymphoma proceeds by distinct oncogenic mechanisms

This study was undertaken to further elucidate the biological mechanisms underlying the frequent event of transformation of follicular lymphoma (FL) to diffuse large B-cell lymphoma (t-FL). The gene expression profiles of 20 paired lymph node biopsies, derived from the same patient pre- and post-transformation, were analysed using the Lymphochip cDNA microarray. TP53 mutation analysis was performed and copy number alterations at the c-REL and CDNK2A examined. Immunohistochemistry was performed on an independent panel of paired transformation paraffin-embedded samples. Transformed follicular lymphoma was predominantly of the germinal centre B-like phenotype both at the mRNA and protein level. Despite this homogeneity, transformation proceeded by at least two pathways. One mechanism was characterised by high proliferation, as assessed by the co-ordinately expressed genes of the proliferation signature. This group was associated with the presence of recurrent oncogenic abnormalities. In the remaining cases, proliferation was not increased and transformation proceeded by alternative routes as yet undetermined. Genes involved in cellular proliferation prevailed amongst those that were significantly increased upon transformation and T cell and follicular dendritic-associated genes predominated amongst those that decreased. t-FL is a germinal centre B (GCB)-like malignancy that evolves by two pathways, one that is similar in proliferation rate to the antecedent FL and the other that has a higher proliferation rate and is characterised by the presence of recognised oncogenic abnormalities.     

Cyclin Dl expression in B-cell non Hodgkin lymphoma

Disorders of the cell cycle regulatory machinery play a key role in the pathogenesis of cancer. Over-expression of cyclin D1 protein has been reported in several solid tumors and certain lymphoid malignancies, but little is known about the effect of its expression on clinical behavior and outcome in B-cell Non-Hodgkin lymphoma (NHL). In this study, we investigated the expression of cyclin Dl in group of patients with NHL and correlated the results with the clinical and laboratory data. The degree of expression of cyclin Dl protein was evaluated by flow cytometry in a group of NHL patients (n = 46) and in normal control group (n = 10). Cyclin Dl over expression was detected in 10 out of 46 (21.7%) patients; they were 5/5-mantle cell lymphoma (MCL) (100%) and 5/28 large B-cell lymphoma (17.8%). All other NHL subtypes showed normal cyclin D1 expression. The clinical signs (hepatomegaly, splenomegaly and B-symptoms, clinical staging) and laboratory data (hemoglobin, white cell count (WBCs), platelet count, and bone marrow infiltration) were not significantly different between NHL subgroup with cyclin Dl over expression and that with normal cyclin Dl expression. Serum lactic dehydrogenase (LDH) levels and lymphadenopathy were significantly higher in NHL group with cyclin D1 over expression as compared to those without. Also, cyclin D1 over expression is associated with poor outcome of NHL patients. Cyclin Dl over expression was evident among all cases of MCL and few cases of large B-cell lymphoma. Cyclin Dl over expression might be used as adjuvant tool for diagnosis of MCL; has role in NHL biology and is bad prognostic index in NHL.     

Deletions at 11q23 in different lymphoma subtypes

BACKGROUND AND OBJECTIVES: Chromosome band 11q23 is frequently deleted in various types of neoplasm. The region represented by yeast artificial chromosome (YAC) clone 755b11 at 11q23 has been shown to be the minimal common region of deletion in mantle cell lymphoma (MCL) and B-cell chronic lymphocytic leukemia (B-CLL). The aim of the study was to determine the frequencies of 11q23 deletion in different lymphoma subtypes. DESIGN AND METHODS: We performed fluorescence in situ hybridization (FISH) analysis with YAC755b11 on either peripheral blood or lymph node biopsy (LN) specimens of patients diagnosed as having MCL (47), CLL/small lymphocytic lymphoma (SLL) (62), diffuse large cell lymphoma (DLCL) (17), follicular lymphoma (FL) (9), and Hodgkin's disease (HD) (11). Fifteen cases of reactive or normal lymph node biopsies were studied as controls. RESULTS: Forty of the 161 (25%) samples exhibited deletions in the region represented by YAC755b11. The 11q23 deletion was found only in MCL (23, 49%), CLL / SLL (13, 21%) and DLCL (4, 24%). Three cases were classified as Richter's syndrome and they all exhibited the deletion at 11q23. The deletion frequencies in the blood specimens of typical CLL (30%) and lymph node specimens of CLL/SLL (13%) were remarkably different. INTERPRETATION AND CONCLUSIONS: Our study demonstrated that the 11q23 deletion is not common in lymphomas other than MCL, CLL and DLCL. It also showed the possible correlation of the 11q23 deletion with the transformation of localized lymphoma to CLL, and with the development of Richter's syndrome.     

Deletions involving two distinct regions of 6q in B-cell non-Hodgkin lymphoma.

The recurrent loss of genetic material from a specific chromosomal region in a given tumor type suggests the presence of a tumor-suppressor gene, the loss or inactivation of which may be relevant for tumorigenesis. In this study, we provide molecular evidence for the recurrent association between deletions on the long arm of chromosome 6 and B-cell non-Hodgkin lymphoma (B-NHL). Normal and tumor DNAs from 71 cases of B-NHL were studied for loss of constitutional heterozygosity (LOH) at 19 loci on chromosome 6 using a panel of restriction fragment length polymorphism (RFLP) probes. LOH, indicating deletion of all or part of 6q, was detected in 16 of 71 cases (22.5%), ranging from low-grade to high-grade B-NHL. The isolated loss of 6p or the loss of other chromosomes (8, 17, 22) tested as controls for specificity was not observed in any case. Comparison of the extent of the deletions among different cases allowed the identification of two distinct regions of minimal deletion (RMD) at 6q25 to 6q27 (RMD-1) and at 6q21 to 6q23 (RMD-2), respectively, suggesting the existence of two tumor-suppressor genes. These data support a role for 6q deletions in B-NHL pathogenesis and provide a basis for identifying the corresponding tumor-suppressor genes.     

Cyclin D1 expression in B-cell non Hodgkin lymphoma

Disorders of the cell cycle regulatory machinery playa key role in the pathogenesis of cancer. Over-expression of cyclin D1 protein has been reported in several solid tumors and certain lymphoid malignancies, but little is known about the effect of its expression on clinical behavior and outcome in B-cell Non-Hodgkin lymphoma (NHL).

In this study, we investigated the expression of cyclin D1 in group of patients with NHL and correlated the results with the clinical and laboratory data. The degree of expression of cyclin D1 protein was evaluated by flow cytometry in a group of NHL patients (n = 46) and in normal control group (n = 10). Cyclin D1 over expression was detected in 10 out of 46 (21.7%) patients; they were 5/5-mantle cell lymphoma (MCL) (100%) and 5/28 large B-cell lymphoma (17.8%). All other NHL subtypes showed normal cyclin D1 expression. The clinical signs (hepatomegaly, splenomegaly and B-symptoms, clinical staging) and laboratory data (hemoglobin, white cell count (WBCs), platelet count, and bone marrow infiltration) were not significantly different between NHL subgroup with cyclin D1 over expression and that with normal cyclin D1 expression. Serum lactic dehydrogenase (LDH) levels and lymphadenopathy were significantly higher in NHL group with cyclin D1 over expression as compared to those without. Also, cyclin Dl over expression is associated with poor outcome of NHL patients.

Cyclin D1 over expression was evident among all cases of MCL and few cases of large B-cell lymphoma. Cyclin D1 over expression might be used as adjuvant tool for diagnosis of MCL; has role in NHL biology and is bad prognostic index in NHL.     

miRNA expression in diffuse large B-cell lymphoma treated with chemoimmunotherapy

Diffuse large B-cell lymphoma (DLBCL) prognostication requires additional biologic markers. miRNAs may constitute markers for cancer diagnosis, outcome, or therapy response. In the present study, we analyzed the miRNA expression profile in a retrospective multicenter series of 258 DLBCL patients uniformly treated with chemoimmunotherapy. Findings were correlated with overall survival (OS) and progression-free survival (PFS). miRNA and gene-expression profiles were studied using microarrays in an initial set of 36 cases. A selection of miRNAs associated with either DLBCL molecular subtypes (GCB/ABC) or clinical outcome were studied by multiplex RT-PCR in a test group of 240 cases with available formalin-fixed, paraffin-embedded (FFPE) diagnostic samples. The samples were divided into a training set (123 patients) and used to derive miRNA-based and combined (with IPI score) Cox regression models in an independent validation series (117 patients). Our model based on miRNA expression predicts OS and PFS and improves upon the predictions based on clinical variables. Combined models with IPI score identified a high-risk group of patients with a 2-year OS and a PFS probability of < 50%. In summary, a precise miRNA signature is associated with poor clinical outcome in chemoimmunotherapy-treated DLBCL patients. This information improves upon IPI-based predictions and identifies a subgroup of candidate patients for alternative therapeutic regimens.     

MicroRNA-21 regulates the sensitivity of diffuse large B-cell lymphoma cells to the CHOP chemotherapy regimen

Numerous studies have demonstrated that microRNA-21 (miR-21), as an oncogene, is involved in the occurrence of many types of tumor and the sensitivity of tumor cells to chemotherapeutic drugs. In the present study, we investigated whether miR-21 is involved in regulating the sensitivity of the diffuse large B-cell lymphoma (DLBCL) cell line CRL2631 to the cyclophosphamide, vincristine, Adriamycin, and prednisone (CHOP) chemotherapeutic regimen. Knockdown of miR-21 with antisense oligonucleotides significantly increased the cytotoxic effects of the CHOP regimen in CRL2631 cells. A luciferase reporter assay showed that PTEN is a target gene of miR-21 in CRL2631 cells, and subsequent experiments demonstrated that miR-21 impacts the PI3K/AKT signaling pathway through the regulation of PTEN, thereby affecting cellular sensitivity to the CHOP chemotherapeutic regimen. Furthermore, knockdown of NF-κB decreased miR-21 expression and sensitized CRL2631 cells to CHOP treatment. These results provide evidence that it may be possible to overcome microRNA-based DLBCL drug resistance.     

Comparison of genome profiles for identification of distinct subgroups of diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) comprises molecularly distinct subgroups such as activated B-cell-like (ABC) and germinal center B-cell-like (GCB) DLBCLs. We previously reported that CD5(+) and CD5(-)CD10(+) DLBCL constitute clinically relevant subgroups. To determine whether these 2 subgroups are related to ABC and GCB DLBCLs, we analyzed the genomic imbalance of 99 cases (36 CD5(+), 19 CD5(-)CD10(+), and 44 CD5(-)CD10(-)) using array-based comparative genomic hybridization (CGH). Forty-six of these cases (22 CD5(+), 7 CD5(-)CD10(+), and 17 CD5(-)CD10(-)) were subsequently subjected to gene-expression profiling, resulting in their division into 28 ABC (19 CD5(+) and 9 CD5(-)CD10(-)) and 18 GCB (3 CD5(+), 7 CD5(-)CD10(+), and 8 CD5(-)CD10(-)) types. A comparison of genome profiles of distinct subgroups of DLBCL demonstrated that (1) ABC DLBCL is characterized by gain of 3q, 18q, and 19q and loss of 6q and 9p21, and GCB DLBCL is characterized by gain of 1q, 2p, 7q, and 12q; (2) the genomic imbalances characteristic of the CD5(+) and CD5(-)CD10(+) groups were similar to those of the ABC and GCB types, respectively. These findings suggest that CD5(+) and CD5(-)CD10(+) subgroups are included, respectively, in the ABC and GCB types. Finally, when searching for genomic imbalances that affect patients' prognosis, we found that 9p21 loss (p16(INK4a) locus) marks the most aggressive type of DLBCL.     

Gene expression profiling of diffuse large B-cell lymphoma supervised by CD21 expression

This study investigated the gene expression profiles of 40 cases of diffuse large B-cell lymphoma (DLBCL) according to CD21 expression, a favourable prognostic factor in DLBCL. Signature genes were analysed by Gene Ontology Tree Machine, and genes concerned with the immune system and related categories were significantly upregulated in CD21⁻ DLBCLs. Of 40 DLBCLs, four were germinal centre B cell-like (GCB) and 36 non-GCB. Of the 36 non-GCB DLBCLs, 14 CD21⁺ DLBCLs showed significantly better overall survival than the 22 CD21⁻ DLBCLs ( P  =   0·036). Hierarchical cluster analysis of signature genes related to CD21 was applied to previously published data sets, resulting in two groups for each data set, CD21⁺ type DLBCLs and CD21⁻ type DLBCLs. Survival of CD21⁺ type DLBCLs was significantly better than that of CD21^– type ( P  =   0·006 and P  =   0·004, respectively). In both data sets, CD21⁺ type DLBCLs predominantly included GCB DLBCLs compared with CD21⁻ type. The top classifier gene of CD21 expression was IGHM, and the five of nine Gene Ontology categories significant in CD21^– DLBCLs included IGHM . Immunohistochemical analysis of 216 DLBCLs confirmed that overall survival of surface (s) IgM⁺ DLBCLs was significantly poorer than that of sIgM^- DLBCLs ( P  =   0·013).