Analysis of chromosomal imbalances in de novo CD5-positive diffuse large-B-cell lymphoma detected by comparative genomic hybridization

CD5+ diffuse large B-cell lymphoma: a narrative review

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous entity, and cell surface cluster of differentiation (CD) 5 expression may represent a distinct subset. Here, we provide a narrative review of CD5+ DLBCL to understand its clinical implications. Between 5-10% of DLBCL express CD5, making it an uncommon subset. Studies have variably shown that CD5+ DLBCL may be associated with increased age, high lactate dehydrogenase, B symptoms, extra-nodal sites, higher International Prognostic Index score, and advanced stage. CD5+ DLBCLs are more likely to express Bcl-2, MYC, and MUM1; a large proportion exhibit an activated B-cell (ABC)-like phenotype. The balance of studies generally supports an independent prognostic value of CD5 in DLBCL While more aggressive first-line regimens have been advocated for CD5+ DLBCL, including dose-adjusted R-EPOCH and autologous stem cell transplant, evidence to support these approaches is lacking; further study is warranted to identify the optimal treatment strategy for this disease entity.

Prognostic Significance of in situ Phenotypic Marker Expression in Diffuse Large B-cell Lymphomas

Diffuse large B-cell lymphomas (DLBCL) are the most common lymphoid malignancies, and encompass all malignant lymphomas characterized by large neoplastic cells and B-cell derivation. In the last decade, DLBCL has been subjected to intense clinical, phenotypic and molecular studies, and were found to represent a heterogeneous group of tumors. These studies suggested new disease subtypes and variants with distinct clinical characteristics, morphologies, immunophenotypes, genotypes or gene expression profiles, associated with distinct prognoses or unique sensitivities to particular therapy regimens. Unfortunately, the reliability and reproducibility of the molecular results remains unclear due to contradictory reports in the literature resulting from small sample sizes, referral and selection biases, and variable methodologies and cut-off levels used to determine positivity. Here, we review phenotypic studies on the prognostic significance of protein expression profiles in DLBCL and reconsider our own retrospective data on 301 primary DLBCL cases obtained on a previously validated tissue microarray in light of powerful statistical methods of determining optimal cut-off values of phenotypic factors for prediction of outcome.

Lkb1 deletion in murine B lymphocytes promotes cell death and cancer

LKB1 (also known as STK11) is a potent tumor suppressor in solid tumors, such as melanoma and lung adenocarcinoma, but inactivation in hematopoietic cells causes cell death without signs of tumorigenesis. We noted somatic LKB1 deletion or mutation at low frequency in human B-cell lymphoma. To determine if LKB1 inactivation is a passenger or driver event in lymphoid cancers, we examined the effects of conditional inactivation of Lkb1 in murine lymphocytes. Consistent with prior reports, Lkb1 deletion in either T or B cells resulted in massive, lineage-specific apoptosis. Surprisingly, despite an 80% reduction of peripheral B-cell number, animals harboring somatic B-lineage Lkb1 deletion developed aggressive B-cell lymphoma with high penetrance and moderate latency. Malignant B cells exhibited somatic Lkb1 recombination. In contrast, Lkb1 deletion in T cells did not promote tumorigenesis. Concomitant Ras activation with Lkb1 deletion reduced T-cell apoptosis, but did not enhance tumor formation in T or B cells. These results suggest that although physiologic LKB1 expression exerts a potent pro-survival effect in lymphocytes, LKB1 inactivation nonetheless facilitates transformation of B, but not T, lymphocytes.

Burkitt-Type Acute Lymphoblastic Leukemia With Precursor B-Cell Immunophenotype and Partial Tetrasomy of 1q: A Case Report

Burkitt-type acute lymphoblastic leukemia (B-ALL) is thought as a variant of Burkitt lymphoma/leukemia and derived from mature B-cell lymphoblast.B-ALL was developed in a 10-year-old girl. Two characteristics were apparent in this case. First, the lymphoblastic cells were positive for CD10, CD19, CD20, and CD22, but negative for terminal deoxynucleotidyl transferase and surface immunoglobulins, indicating a B-cell immunophenotype. The detection of t(8;14)(q24;q32) with a chromosomal analysis is required for a diagnosis of B-ALL. Second, der(1)(pter → q32.1::q32.1 → q21.1::q11 → qter) was detected, in which 1q21.1 to 1q32.1 was inverted and inserted. Finally, partial tetrasomy of 1q was also present. Because B-ALL with abnormal chromosome 1 has been reported poor outcome, the usual chemotherapy for stage 4 Burkitt lymphoma with added rituximab was administered for our patient.We report B-ALL with precursor B-cell immunophenotype and interesting partial tetrasomy of 1q.

Whole-exome analysis reveals novel somatic genomic alterations associated with outcome in immunochemotherapy-treated diffuse large B-cell lymphoma

Lack of remission or early relapse remains a major clinical issue in diffuse large B-cell lymphoma (DLBCL), with 30% of patients failing standard of care. Although clinical factors and molecular signatures can partially predict DLBCL outcome, additional information is needed to identify high-risk patients, particularly biologic factors that might ultimately be amenable to intervention. Using whole-exome sequencing data from 51 newly diagnosed and immunochemotherapy-treated DLBCL patients, we evaluated the association of somatic genomic alterations with patient outcome, defined as failure to achieve event-free survival at 24 months after diagnosis (EFS24). We identified 16 genes with mutations, 374 with copy number gains and 151 with copy number losses that were associated with failure to achieve EFS24 (P<0.05). Except for FOXO1 and CIITA, known driver mutations did not correlate with EFS24. Gene losses were localized to 6q21-6q24.2, and gains to 3q13.12-3q29, 11q23.1-11q23.3 and 19q13.12-19q13.43. Globally, the number of gains was highly associated with poor outcome (P=7.4 × 10⁻¹²) and when combined with FOXO1 mutations identified 77% of cases that failed to achieve EFS24. One gene (SLC22A16) at 6q21, a doxorubicin transporter, was lost in 54% of EFS24 failures and our findings suggest it functions as a doxorubicin transporter in DLBCL cells.

Recent advances in de novo CD5+ diffuse large B cell lymphoma

Various subsets of DLBCL are distinguished based on molecular and immunohistochemical features. CD5 expressing DLBCL (CD5+ DLBCL) is increasingly recognized as a subtype of DLBCL with an aggressive disease course. Primary CD5+ DLBCL comprises approximately 5-10% of DLBCL. Few studies of CD5+ DLBCL have been reported, primarily from Japan. Publications covered in this review include articles published on PubMed and abstracts from major international conferences until April 2013. Common features of patients with CD5+ DLBCL are older age, female preponderance, elevated LDH, more extra-nodal involvement, poor performance status (PS), higher incidence of CNS involvement, inferior response to rituximab-containing regimens (as compared to CD5- DLBCL) and advanced stage. The majority of these cases belong to the activated B cell subtype (ABC) of DLBCL. It is unclear whether CD5 expression in malignant B cells may confer chemo resistance, upregulate antiapoptotic signals and alter the microenvironment. Molecular techniques have helped in understanding CD5+ DLBCL. Gene expression signature was similar in ABC-DLBCL and CD5+ DLBCL in some studies. Despite the better characterization treatment outcomes are poor and additional studies are needed.

Genotypic and phenotypic differences between nodal and extranodal diffuse large B-Cell lymphomas

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of diseases that have diverse clinical, pathological, and biological features. Here, it is shown that primary nodal and extranodal DLBCLs differ genomically and phenotypically. Using conventional comparative genomic hybridization (CGH), the authors assessed the chromosomal aberrations in 18 nodal, 13 extranodal, and 5 mixed DLBCLs. The results demonstrate significantly distinct chromosomal aberrations exemplified by gains of chromosomal arms 1p, 7p, 12q24.21-12q24.31, and 22q and chromosome X and loss of chromosome 4, 6q, and 18q22.3-23 in extranodal compared with nodal DLBCLs. Nodal DLBCLs showed an increased tendency for 18q amplification and BCL2 protein overexpression compared with extranodal and mixed tumors. Using a panel of five antibodies against GCET1, MUM1, CD10, BCL6, and FOXP1 proteins to subclassify DLBCLs according to the recent Choi algorithm, the authors showed that the genomic profiles observed between the nodal and extranodal DLBCLs were not due to the different proportions of GCB vs ABC in the two groups. Further delineation of these genomic differences was illuminated by the use of high-resolution 21K BAC array CGH performed on 12 independent new cases of extranodal DLBCL. The authors demonstrated for the first time a novel genome and proteome-based signatures that may differentiate the two lymphoma types.

Amplification at 11q23 targets protein kinase SIK2 in diffuse large B-cell lymphoma

In diffuse large B-cell lymphoma (DLBCL), several recurrent chromosomal aberrations have been described where the presumed target genes remain unknown, including gain/amplification at 11q23-24. Here, we characterized amplification at 11q23 in the DLBCL cell line KARPAS-422. Quantitative genomic PCR and FISH analysis were used to define the region altered, thus showing an amplification peak at 111.1 Mb, the region hosting SIK2/SNF1LK2. Expression profiling, quantitative RT-PCR, Western blot, and immunocytology identified overexpression of SIK2, highlighting this gene as a likely key target of 11q23 amplification. SIK2 encodes a protein kinase that has been shown to inhibit transcription factor CREB via phosphorylation of its cofactor TORC2/CRTC2. Accordingly, siRNA-mediated downregulation of SIK2 expression resulted in upregulation of the CREB target gene BIM. Functional analysis by treatments with cAMP, the glucocorticoid dexamethasone, and 2-deoxy-d-glucose revealed a regulatory role for SIK2 in survival and glucose metabolism, respectively. However, overexpression of SIK2 was not detectable in primary DLBCL samples. Nevertheless, identification of SIK2 as an amplification target highlights this kinase along with its regulatory network as potential therapeutic targets in DLBCL.

Pathogenesis of diffuse large B cell lymphoma

Substantial additional insight has been obtained in the past decade regarding the pathogenesis of diffuse large B cell lymphoma (DLBCL). Distinct subtypes of DLBCL have been defined by gene expression profiling (GEP) and they differ not only in GE profiles but also in the pattern of genetic abnormalities. The ability to correlate corresponding genetic and GEP data markedly facilitates the identification of target genes in regions with copy number abnormalities. Oncogenic pathways are often differentially activated in these different subtypes of DLBCL, suggesting that therapy should be targeted according to these differences. The tumor microenvironment plays a significant role in determining outcome and may be a novel target for therapy. The role of microRNA in lymphomagenesis is increasingly being recognized and mutation of key genes has been demonstrated to drive the activation of the NF-kappaB pathway and B cell receptor signaling. The pace of discovery will be even more rapid in the near future with the convergence of data from multiple complementary genome-wide studies and technological innovations including the rapid advance in the technology of high-throughput sequencing.

The therapeutic effect of rituximab on CD5-positive and CD5-negative diffuse large B-cell lymphoma

The prognosis of diffuse large B-cell lymphoma (DLBCL) has improved markedly in recent years of rituximab era. The prognosis of de novo CD5-positive DLBCL is reported to be poor, but the effect of rituximab on this type of lymphoma remains unclear. To investigate the effect of rituximab on CD5-positive DLBCL, we collected DLBCL patients and analysed prognostic factors. A total of 157 patients with DLBCL who were immunophenotyped with flow-cytometry (FCM) and treated with chemotherapy were subjected to analysis. Those treated with radiotherapy alone or with supportive therapy only were not included. Patients diagnosed in 2003 or later were treated with rituximab combined chemotherapy. There were 95 males and 62 females. Their age ranged from 20 to 91 years old, and the median was 65 years. Nineteen patients were diagnosed as having de novo CD5-positive DLBCL. Rituximab was given alongside chemotherapy in 85 patients. Of these, 11 were positive for CD5 and 74 were negative. The addition of rituximab improved the overall survival (OS) of DLBCL patients (2-year OS: 82% vs. 70%, p = 0.01). For CD5-negative DLBCL, patients treated with rituximab showed 2-year OS of 84%, which was significantly better than those treated without rituximab (70%, p = 0.008). However, for CD5-positive DLBCL, the prognosis was not statistically different between the patients treated with and without rituximab (59% vs. 50%, p = 0.72). Although rituximab improved the prognosis of DLBCL, such improvement was restricted to the CD5-negative group. Further investigation is required to improve the prognosis of patients with CD5-positive DLBCL.

Chromosomal imbalances in pediatric Burkitt-like lymphoma and review of the literature in relation to other germinal center derived B-cell tumors

This study reports on the cytogenetic features of a novel case of pediatric Burkitt-like lymphoma (BLL), that adds to the three published. Four groups of cytogenetic abnormalities were detected in the present case: (1) imbalances shared by most germinal center (GC) derived B-cell tumors including BLL (+1q, -6q, -8p, +8q24 and +11); (2) imbalances already reported in adult but not in pediatric BLL cases and shared with most GC B-cell tumors (+7, -9p, -9q, +12q, -13q, +17, +19, -3 and -4); (3) imbalances already reported in pediatric but not in adult BLL cases and shared with some GC B-cell tumors (-2q); and (4) imbalances never described before in pediatric or adult BLL, but present in different GC B-cell tumors (-6p, -1p and -18q). In view of the paucity of pediatric BLL cases published, this report adds novel, relevant information on the molecular cytogenetic features of this rare tumor.

MicroRNA expression in lymphoid malignancies: new hope for diagnosis and therapy?

microRNAs are a newly discovered class of short (∼22 nt) naturally occurring single-stranded RNA molecules that regulate the expression of target genes post-transcriptionally. Despite only being discovered 7 years ago, microRNAs have been implicated as key regulatory molecules in nearly every biological process examined so far and abnormal expression of microRNAs have been linked to many forms of disease including cancer where they can function as both tumour-suppressors and oncogenes. So why are microRNAs causing so much excitement? And will this excitement translate into new medical breakthroughs? This review attempts to answer these questions in the wider context of cancer, focusing on the role that microRNAs play in normal lymphoid development and malignancy.

CD5 expression is potentially predictive of poor outcome among biomarkers in patients with diffuse large B-cell lymphoma receiving rituximab plus CHOP therapy

BACKGROUND

Several biomarkers indicating poor prognosis have been reassessed in patients receiving rituximab combination chemotherapy for diffuse large B-cell lymphoma (DLBCL). However, few studies have investigated outcome in relation to a combination of these biomarkers. In addition, no large-scale studies have reassessed the outcome of patients with CD5-positive DLBCL treated with rituximab.

PATIENTS AND METHODS

We conducted a retrospective study and investigated the predictive value of three biomarkers -- BCL2, germinal center (GC) phenotype and CD5 -- in 121 DLBCL patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone.

RESULTS

CD5-positive patients showed significantly poorer event-free survival (EFS) and overall survival (OS) than CD5-negative patients (2-year EFS, 18% versus 73%, P < 0.001; 2-year OS, 45% versus 91%, P = 0.001). However, no significant difference in outcome according to BCL2 or GC phenotype was observed. Multivariate analysis revealed that CD5 expression was a significant prognostic factor for EFS [hazard ratio 14.2, 95% confidence interval (CI) 4.7-43.2] and OS (hazard ratio 20.3, 95% CI 3.6-114.4).

CONCLUSIONS

CD5 expression was the only significant prognostic factor among the biomarkers examined in this study. Further studies with larger numbers are warranted to confirm the prognostic significance of CD5 expression for patients with DLBCL receiving rituximab-containing chemotherapy.

Advances in the understanding of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a well-defined lymphoid neoplasm characterized by a proliferation of mature B lymphocytes expressing CD5 that may show a spectrum of morphological and phenotypic features broader than initially described. Although some patients may follow an indolent clinical evolution, in most of them the tumour has an aggressive behaviour with poor response to conventional chemotherapy. The genetic hallmark is the t(11;14)(q13;q32) translocation leading to the overexpression of cyclin D1, which is considered the initial oncogenic event. In addition to this translocation, MCL may carry a high number of secondary chromosomal and molecular alterations that target regulatory elements of the cell cycle machinery and senescence (BMI1/INK4/ARF/CDK4/RB1), DNA damage response pathways (ATM/CHK2/p53), and cell survival signals. The knowledge of these mechanisms and their influence on the behaviour of the tumour are facilitating the development of prognostic models with a more precise prediction of the clinical evolution of the patients. This information coupled with the availability of a new generation of innovative drugs targeting basic molecular process of the tumour cells, should facilitate the design of new therapeutic protocols able to overcome the resistance of this aggressive lymphoma to conventional treatments and improve the life expectancy of the patients.

"Myc'ed messages": myc induces transcription of E2F1 while inhibiting its translation via a microRNA polycistron

The recent revelation that there are small, noncoding RNAs that regulate the expression of many other genes has led to an exciting, emerging body of literature defining the biological role for these molecules within signaling networks. In a flurry of recent papers, a microRNA polycistron induced by the oncogenic transcription factor c-myc has been found to be involved in an unusually structured network of interactions. This network includes the seemingly paradoxical transcriptional induction and translational inhibition of the same molecule, the E2F1 transcription factor. This microRNA cluster has been implicated in inhibiting proliferation, as well as inhibiting apoptosis, and promoting angiogenesis. Consistent with its seemingly paradoxical functions, the region of the genome in which it is encoded is deleted in some tumors and overexpressed in others. We consider the possibility that members of this polycistronic microRNA cluster help cells to integrate signals from the environment and decide whether a signal should be interpreted as proliferative or apoptotic.

MicroRNAs and haematology: small molecules, big function

MicroRNAs are a recently discovered class of small ( approximately 22nt) endogenously expressed translational-repressor RNAs that play key roles in many cellular pathways and whose aberrant expression appears to be a common feature of malignancy. MicroRNAs are expressed in specific haematological cell types and play important regulatory roles in early haematopoietic differentiation, erythropoiesis, granulocytosis, megakaryocytosis and lymphoid development. Additionally, there is an emerging body of research to suggest that microRNAs play an important role in the pathology of haematological malignancies. MicroRNAs have been found to act as both tumour suppressor molecules [e.g. MIRN15A (miR-15a), MIRN16-1 (miR-16-1)] in leukaemias and have oncogenic properties [e.g. MIRN155 (miR-155) and MIRN17-92 (miR-17-miR-92) cluster] in lymphomas. This review discusses the rapidly accumulating research that points to the major role microRNAs play in both haematopoiesis and haematological malignancy.

Construction and analysis of tree models for chromosomal classification of diffuse large B-cell lymphomas

AIM: To construct tree models for classification of diffuse large B-cell lymphomas (DLBCL) by chromosome copy numbers, to compare them with cDNA microarray classification, and to explore models of multi-gene, multi-step and multi-pathway processes of DLBCL tumorigenesis.

METHODS: Maximum-weight branching and distance-based models were constructed based on the comparative genomic hybridization (CGH) data of 123 DLBCL samples using the established methods and software of Desper et al. A maximum likelihood tree model was also used to analyze the data. By comparing with the results reported in literature, values of tree models in the classification of DLBCL were elucidated.

RESULTS: Both the branching and the distance-based trees classified DLBCL into three groups. We combined the classification methods of the two models and classified DLBCL into three categories according to their characteristics. The first group was marked by +Xq, +Xp, -17p and +13q; the second group by +3q, +18q and +18p; and the third group was marked by -6q and +6p. This chromosomal classification was consistent with cDNA classification. It indicated that -6q and +3q were two main events in the tumorigenesis of lymphoma.

CONCLUSION: Tree models of lymphoma established from CGH data can be used in the classification of DLBCL. These models can suggest multi-gene, multi-step and multi-pathway processes of tumorigenesis. Two pathways, -6q preceding +6q and +3q preceding +18q, may be important in understanding tumorigenesis of DLBCL. The pathway, -6q preceding +6q, may have a close relationship with the tumorigenesis of non-GCB DLBCL.

De novo CD5+ diffuse large B cell lymphoma with basophilia in the peripheral blood: successful treatment with autologous peripheral blood stem cell transplantation

Basophils play an important role in allergic inflammation and are pathologically related to hematological disturbances, such as iron deficiency anemia and myeloproliferative disorders; however, they are only rarely encountered in lymphoid malignancies. Here, we report the case of a 33-year-old man with a bulky mass of the small intestine, multiple paraaortic lymphoadenopathy, pleural effusion, and ascites, who was diagnosed as a case of de novo CD5+ diffuse large B cell lymphoma (DLBCL). This patient showed a marked elevation of the basophil count in the peripheral blood, which appeared to run in parallel with the tumor burden. High dose chemotherapy followed by autologous peripheral blood cell transplantation yielded complete remission, and the patient has remained disease free for 5 years. To the best of our knowledge, this is the first report of a case of de novo CD5+ DLBCL showing marked elevation of the PB basophil count.

Expression profiling analysis of the CD5+ diffuse large B-cell lymphoma subgroup: development of a CD5 signature

Diffuse large B-cell lymphoma (DLBCL) accounts for 30% of non-Hodgkin's lymphomas and is known to comprise heterogeneous groups. We previously reported that CD5+ DLBCL is a clinically distinct subgroup of these tumors that is associated with poor prognosis. In our current study, we have used gene expression profiling technology in an attempt to identify new markers and to further characterize the biological features of CD5+ DLBCL. Candidate genes, which showed the greatest difference in expression between 22 CD5+ and 26 CD5- DLBCL cases, were selected from our screening and subjected to clustering analysis. This resulted in identification of a specific mRNA profile (a CD5 signature) for CD5+ DLBCL. The CD5 signature included downregulated extracellular matrix genes such as POSTN, SPARC, COL1A1, COL3A1, CTSK, MMP9 and LAMB3, and comprised upregulated genes including TRPM4. We tested this CD5 signature for its potential use as a relevant marker for CD5+ DLBCL and found that it did indeed recognize this subgroup. The tumors identified by the CD5 signature contained most of the CD5+ DLBCL cases and some CD5- DLBCL cases. Moreover, the subgroup of cases with this CD5 signature showed a poorer prognosis. The subsequent application of the CD5 signature to the analysis of an independent series of DLBCL microarray data resulted in identification of a subgroup of DLBCL cases with a similar clinical outcome, further suggesting that the CD5 signature can be used as a clinically relevant marker of this disease.

Jumping translocation of 17q11∼qter and 3q25∼q28 duplication in a variant Philadelphia t(9;14;22)(q34;q32;q11) in a childhood chronic myelogenous leukemia

The virtually obligatory presence of the Philadelphia chromosome may suggest a causal homogeneity, but chronic myelogenous leukemia (CML) is a clinically heterogeneous disease. This may be a consequence of the variable BCR breakpoints on chromosome 22 and of nonrandom secondary chromosomal abnormalities. We present the case of a boy, age 12, investigated in blastic phase of CML. Karyotyping with conventional and multiplex fluorescence in situ hybridization (FISH and M-FISH) karyotyping, complemented with reverse transcriptase-polymerase chain reaction, identified a variant Philadelphia translocation t(9;14;22)(q34;q32;q11) involving a cryptic BCR/ABL fusion with formation of the p190(Bcr-Abl) oncoprotein. M-FISH revealed also an unbalanced jumping translocation of 17q11 approximately qter alternatively present on chromosomes 14 or 20, apparently hithertofore unreported in hematological malignancies. Another secondary aberration, dup(3)(q25q28), was revealed by multipoint interphase FISH (mpI-FISH). Gain of this region is known in adult hematological malignancies and solid tumors, suggesting its general involvement in tumor initiation or progression (or both), regardless of tissue origin.

Gain of 9p due to an unbalanced rearrangement der(9;18): a recurrent clonal abnormality in chronic myeloproliferative disorders

Clonal aberrations leading to gain of 9p--mostly due to trisomy 9--are often reported in polycythemia vera. We report on four cases of chronic myeloproliferative disorders that demonstrated a new recurrent unbalanced rearrangement between chromosomes 9 and 18 leading to trisomy of 9p and a monosomy of 18p. This abnormality was confirmed with fluorescence in situ hybridization using chromosome painting and locus-specific probes. Three cases were diagnosed as polycythemia vera; one case presented with secondary acute myeloid leukemia following idiopathic osteomyelofibrosis. The prognostic impact of this unbalanced aberration and of gains of 9p in chronic myeloproliferative disorders remains to be clarified.

Contig array CGH at 3p14.2 points to the FRA3B/FHIT common fragile region as the target gene in diffuse large B-cell lymphoma

Deletions of the 3p arm have been detected in various solid tumors, but no study to date has investigated this deletion in diffuse large B-cell lymphoma (DLBCL). Recently, we demonstrated that 3p14.2 was deleted in approximately 30% of DLBCL cases by use of a genome-wide array-comparative genomic hybridization (CGH). For a more detailed examination of the genomic losses at 3p14.2, here we made use of contig BAC array for 3p14.2, and found that 12 DLBCL samples displayed losses. All of the deleted regions were located within the fragile histidine triad (FHIT) gene, and the most frequent region of loss was mapped to 0.4 Mbp of the region encompassing the introns 4 and 5 and exon 5 of the FHIT gene. Concomitant analysis of transcripts showed that the FHIT gene was aberrantly transcribed in 31% of the DLBCL samples examined and that the lost exons of the aberrant transcripts were correlated with genomic deletions. These findings indicate that (1) loss of genomic material at 3q14.2 is responsible for exon losses of the FHIT gene, and (2) genomic loss of the FHIT gene is one of the causes of the generation of aberrant transcripts.

Cytogenetic features of de novo CD5-positive diffuse large B-cell lymphoma: Chromosome aberrations affecting 8p21 and 11q13 constitute major subgroups with different overall survival

De novo CD5-positive diffuse large B-cell lymphoma (CD5(+)DLBCL) is regarded as a different clinicopathological entity from CD5-negative DLBCL (CD5(-)DLBCL) and mantle cell lymphoma (MCL). Because only a few published cytogenetic studies of de novo CD5(+)DLBCL are available, we investigated chromosomal changes in 23 Japanese patients who had de novo CD5(+)DLBCL. A characteristic of cytogenetic abnormalities in de novo CD5(+)DLBCL was a high incidence of chromosomal aberrations affecting 8p21 and 11q13. Major chromosomal breakpoints were concentrated at 8p21, 11q13, and 3q27. Patients with 8p21 aberrations showed aggressive clinical features, including advanced stage of disease, elevated serum LDH level, poor performance status, and an inferior survival curve compared with patients who had 11q13 changes (P = .043). Chromosomal abnormalities of both 8p21 and 11q13 were not observed in the same patient, and each abnormality showed different chromosomal gains and losses. These results indicate that de novo CD5(+)DLBCL may occur in previously unidentified subgroups that differ in their chromosomal abnormalities. The conflicting results of previous studies on prognosis may thus be explained in part by the differences in chromosomal changes.

CD5 + Diffuse Large B-Cell Lymphoma Consists of Germline Cases and Hypermutated Cases in the Immunoglobulin Heavy Chain Gene Variable Region

CD5+ diffuse large B-cell lymphoma (DLBCL) has recently been identified as a subgroup with different clinical characteristics from CD5- DLBCL and as having a poorer outcome than CD5- DLBCL. Data regarding differences in gene alteration between CD5+ and CD5- DLBCL have accumulated. In this article, we report an analysis of the immunoglobulin heavy-chain gene variable region (VH) gene in 35 cases of CD5+ DLBCL and compare these cases with those with the germline of the VH gene (GL-VH) and those with a somatically hypermutated VH gene (HM-VH). When the CD5+ DLBCL cases were subdivided with a cutoff value of 98% homology in the VH gene, there were 7 cases (20%) of GL-VH and 28 cases (80%) of HM-VH. The proportion of GL-VH cases in CD5+ DLBCL was more than that in CD5 DLBCL. Although we found no significant difference in pretreatment clinical parameters between the GL-VH and HM-VH subgroups, there was a tendency for the GL-VH subgroup to show lower incidences of elevation of lactate dehydrogenase and >1 site of extranodal involvement compared to the HM-VH subgroup. The overall survival curve of the HM-VH subgroup showed a rapid decline followed by a plateau, whereas that of the GL-VH subgroup declined constantly after 5 years, suggesting that GL-VH disease may not be curable by standard therapies. These findings suggest that CD5+ DLBCL with GL-VH shares clinical features with mantle cell lymphoma, the cellular origin of which has been considered to be pre-germinal center B-cells. We therefore propose that analysis of the VH gene is important for predicting the clinical course of CD5+ DLBCL.

Emerging prognostic factors in diffuse large B cell lymphoma

PURPOSE OF REVIEW

Diffuse large B cell lymphoma (DLBCL) is the most common lymphoma subtype, characterized by marked clinical and biologic heterogeneity. Gene expression studies together with new monoclonal antibody production are playing an increasing role in determining important prognostic factors/biomarkers predictive of outcome. Despite these technical advances, much confusion exists in the literature as to what constitutes the important biomarkers for determining patient outcome. The purpose of this review is to highlight recent advances in our understanding of novel biomarkers in DLBCL and how these might be incorporated into current risk-adjustment models for prognosis.

RECENT FINDINGS

Microarray gene expression analyses have revolutionized our approach to biomarkers in non-Hodgkin lymphomas. Thousands of genes can now be simultaneously analyzed for individual patients, creating a wealth of new data. This has resulted in an improved understanding of the basic biology, as well as the development of new outcome predictors. Monoclonal antibody reagents for some of these biomarkers already exist, allowing for their rapid validation at the level of protein expression and potential clinical translation.

SUMMARY

A molecular classification of DLBCL is a current reality, and together with routine morphology, immunophenotype, and molecular cytogenetics, has allowed us to more accurately subclassify DLBCL and determine clinically relevant subgroups. The time is right to begin to consider how these novel biomarkers should be incorporated into current prognostic models to move beyond the clinically based International Prognostic Index

Comparison of genetic aberrations in CD10+ diffused large B-cell lymphoma and follicular lymphoma by comparative genomic hybridization and tissue-fluorescence in situ hybridization

CD10 is one of the hallmarks of germinal center B-cells where follicular lymphomas (FL) originate. It has not been clearly established, however, whether CD10(+) diffuse B-cell lymphomas (DLBCL) are genetically similar to FL. We therefore examined 19 CD10(+) DLBCL and 40 FL by means of comparative genomic hybridization (CGH) and tissue-fluorescence in situ hybridization (T-FISH). Chromosomal imbalance was more frequently detected in CD10(+) DLBCLs (19/19) than in FLs (24/40). Significant differences were found in eight frequently imbalanced regions, namely those with gains of chromosomes 7q and 12 and those with losses of chromosomes 1p, 4p, 6q, 15q, 16p and 17. Amplification of the 3q region where BCL6 is located is reported to occur frequently in DLBCL, but it was only found in one of the 19 CD10(+) DLBCL cases we examined. The involvement of t(14;18) in CD10(+)+ DLBCL (31%) and in FL (73%) was significantly different (P = 0.0064). The CGH pattern of CD10(+) DLBCL with t(14;18) was also different from that of FL with t(14;18). Taken together, our results indicate that CD10(+) DLBCL constitutes a unique subtype entity with genetic characteristics significantly different from those of FL and DLBCL.

Genome-Wide Array-Based Comparative Genomic Hybridization of Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma and exhibits aggressive and heterogeneous clinical behavior. To genetically characterize DLBCL, we established our own array-based comparative genomic hybridization and analyzed a total of 70 cases [26 CD-positive (CD5+) DLBCL and 44 CD5-negative (CD5-) DLBCL cases]. Regions of genomic aberrations observed in >20% of cases of both the CD5+ and CD5- groups were gains of 1q21-q31, 1q32, 3p25-q29, 5p13, 6p21-p25, 7p22-q31, 8q24, 11q23-q24, 12q13-q21, 16p13, 18, and X and losses of 1p36, 3p14, 6q14-q25, 6q27, 9p21, and 17p11-p13. Because CD5 expression marks a subgroup with poor prognosis, we subsequently analyzed genomic gains and losses of CD5+ DLBCL compared with those of CD5-. Although both groups showed similar genomic patterns of gains and losses, gains of 10p14-p15 and 19q13 and losses of 1q43-q44 and 8p23 were found to be characteristic of CD5+ DLBCL. By focusing on the gain of 13q21-q34 and loss of 1p34-p36, we were also able to identify prognostically distinct subgroups among CD5+ DLBCL cases. These results suggest that array-based comparative genomic hybridization analysis provides a platform of genomic aberrations of DLBCL both common and specific to clinically distinct subgroups.

Genetic and epigenetic factors involved in B-cell lymphomagenesis

Malignant lymphomas have been classified by the WHO into disease categories based not only on histological features, but also on cell surface markers, cytogenetic and clinical features. It is known that chromosome translocation plays an important role in lymphoma development, but it is not entirely clear yet why a given type of chromosome translocation is associated with a specific type of lymphoma. This review deals with molecular mechanisms of B-cell lymphoma development in association with chromosome translocations. The outcome of chromosome translocations can be categorized into three factors: enhancement of proliferation, inhibition of differentiation and anti-apoptotic activity. It is well known that chromosome translocation by itself cannot cause cells to become malignant because it is only one of the growth advantages leading to malignancy, while additional genetic and epigenetic alterations are required for cells to become fully malignant. Mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach are unique in that a majority can be cured by Helicobacter pylori eradication, although 20 to 30% remain resistant. Others as well as we have demonstrated that the presence of the API2-MALT1 chimeric gene correlates well with resistance to H. pylori eradication treatment. These characteristics have led to the speculation that the classification of MALT lymphoma falls somewhere between tumor and inflammation. Although MALT lymphoma seems to have unique features in comparison with other types of B-cell lymphomas, it shares common molecular mechanisms with B-cell lymphoma development.

Identification and characterization of a novel gene, C13orf25, as a target for 13q31-q32 amplification in malignant lymphoma

The amplification at 13q31-q32 has been reported in not only hematopoietic malignancies but also in other solid tumors. We identified previously frequent amplification of chromosomal band 13q31-q32 in 70 cases of diffuse large B-cell lymphoma patients by conventional comparative genomic hybridization analysis. In an attempt to identify a candidate gene within this region, we used array comparative genomic hybridization and fluorescent in situ hybridization to map the 13q31-q32 amplicon. We then screened the 65 expressed sequence tags and Glypican 5 (GPC5) by reverse transcription-PCR and Northern blotting. As a result, we identified a novel gene, designated Chromosome 13 open reading frame 25 (C13orf25), which was overexpressed in B-cell lymphoma cell lines and diffuse large B-cell lymphoma patients with 13q31-q32 amplifications. However, GPC5, which has been reported to be a target gene for 13q31-q32 amplification, was truncated in one cell line, Rec1, possessing the amplification, and its expression in various cell lines with amplification at 13q31-q32 was not significantly different from that in other cell lines without amplification, suggesting that GPC5 is not likely to be the candidate gene. Additional analysis identified two major transcripts in the C13orf25 gene. The two transcripts A and B predicted open reading frames of 32 and 70-amino acid polypeptides, respectively. The former has been reported as bA121J7.2, which is conserved among species. Transcript-B also contained seven mature microRNAs in its untranslated region. These results suggest that the C13orf25 gene is the most likely candidate gene for the 13q31-q32 amplicon found in hematopoietic malignancies.