Specific secondary genetic alterations in mantle cell lymphoma provide prognostic information independent of the gene expression-based proliferation signature

Genomic profiling of mantle cell lymphoma

Genomic profiling of mantle cell lymphoma (MCL) cells has enabled a better understanding of the complex mechanisms underlying the pathogenesis of disease. Besides the t(11;14)(q13;q32) leading to cyclin D1 overexpression, MCL exhibits a characteristic pattern of DNA copy number aberrations that differs from those detected in other B-cell lymphomas. These genomic changes disrupt selected oncogenes and suppressor genes that are required for lymphoma development and progression, many of which are components of cell cycle, DNA damage response and repair, apoptosis, and cell-signaling pathways. Additionally, some of them may represent effective therapeutic targets. A number of genomic and molecular abnormalities have been correlated with the clinical outcome of patients with MCL and are considered prognostic factors. However, only a few genomic markers have been shown to predict the response to current or novel targeted therapies. One representative example is the high-level amplification of the BCL2 gene, which predicts a good response to pro-apoptotic BH3 mimetic drugs. In summary, genomic analyses have contributed to the substantial advances made in the comprehension of the pathogenesis of MCL, providing a solid basis for the identification of optimal therapeutic targets and for the design of new molecular therapies aiming to cure this fatal disease.

CCND2 rearrangements are the most frequent genetic events in cyclin D1(-) mantle cell lymphoma

Cyclin D1(-) mantle cell lymphomas (MCLs) are not well characterized, in part because of the difficulties in their recognition. SOX11 has been identified recently as a reliable biomarker of MCL that is also expressed in the cyclin D1(-) variant. We investigated 40 lymphomas with MCL morphology and immunophenotype that were negative for cyclin D1 expression/t(11;14)(q13;q32) but positive for SOX11. These tumors presented clinically with generalized lymphadenopathy, advanced stage, and poor outcome (5-year overall survival, 48%). Chromosomal rearrangements of the CCND2 locus were detected in 55% of the cases, with an IG gene as partner in 18 of 22, in particular with light chains (10 IGK@ and 5 IGL@). No mutations in the phosphorylation motifs of CCND1, CCND2, or CCND3 were detected. The global genomic profile and the high complexity of the 32 cyclin D1(-) SOX11(+) MCL patients analyzed by copy number arrays were similar to the conventional cyclin D1/SOX11 MCL. 17p deletions and high Ki67 expression conferred a significantly worse outcome for the patients. This comprehensive characterization of a large series of cyclin D1(-) MCL patients indicates that these tumors are clinically and biologically similar to the conventional cyclin D1(+) MCL and provides a basis for the proper identification and clinical management of these patients.

Transformation of indolent mantle cell lymphoma to pleomorphic mantle cell lymphoma: case report and review of clinical and morphologic variants

We report a case of indolent mantle cell lymphoma with progression to pleomorphic mantle cell lymphoma 8 years after initial presentation. The first lymph node biopsy showed expanded mantle zones composed of uniformly small B lymphocytes. A cyclin D1 immunohistochemical stain was negative and the patient was observed. Eight years later, the patient developed symptomatic splenomegaly. Microscopic examination of the spleen revealed expanded mantle zones with an increased number of large cells with irregular nuclear contours. Immunohistochemistry for cyclin D1 was positive. A repeat cyclin D1 immunohistochemical staining performed on the initial lymph node biopsy was positive, indicating an inadequate initial study. Immunoglobulin heavy-chain gene rearrangement studies confirmed clonal identity. A revised diagnosis of indolent mantle cell lymphoma with progression to pleomorphic mantle cell lymphoma was rendered. The differential diagnosis of mantle cell lymphoma, including clinical and morphologic variants, is discussed.

A tumour suppressor network relying on the polyamine-hypusine axis

Tumour suppressor genes encode a broad class of molecules whose mutational attenuation contributes to malignant progression. In the canonical situation, the tumour suppressor is completely inactivated through a two-hit process involving a point mutation in one allele and chromosomal deletion of the other. Here, to identify tumour suppressor genes in lymphoma, we screen a short hairpin RNA library targeting genes deleted in human lymphomas. We functionally identify those genes whose suppression promotes tumorigenesis in a mouse lymphoma model. Of the nine tumour suppressors we identified, eight correspond to genes occurring in three physically linked 'clusters', suggesting that the common occurrence of large chromosomal deletions in human tumours reflects selective pressure to attenuate multiple genes. Among the new tumour suppressors are adenosylmethionine decarboxylase 1 (AMD1) and eukaryotic translation initiation factor 5A (eIF5A), two genes associated with hypusine, a unique amino acid produced as a product of polyamine metabolism through a highly conserved pathway. Through a secondary screen surveying the impact of all polyamine enzymes on tumorigenesis, we establish the polyamine-hypusine axis as a new tumour suppressor network regulating apoptosis. Unexpectedly, heterozygous deletions encompassing AMD1 and eIF5A often occur together in human lymphomas and co-suppression of both genes promotes lymphomagenesis in mice. Thus, some tumour suppressor functions can be disabled through a two-step process targeting different genes acting in the same pathway.

Genome-wide miRNA profiling of mantle cell lymphoma reveals a distinct subgroup with poor prognosis

miRNA deregulation has been implicated in the pathogenesis of mantle cell lymphoma (MCL). Using a high-throughput quantitative real-time PCR platform, we performed miRNA profiling on cyclin D1-positive MCL (n = 30) and cyclin D1-negative MCL (n = 7) and compared them with small lymphocytic leukemia/lymphoma (n = 12), aggressive B-cell lymphomas (n = 138), normal B-cell subsets, and stromal cells. We identified a 19-miRNA classifier that included 6 up-regulated miRNAs and 13 down regulated miRNA that was able to distinguish MCL from other aggressive lymphomas. Some of the up-regulated miRNAs are highly expressed in naive B cells. This miRNA classifier showed consistent results in formalin-fixed paraffin-embedded tissues and was able to distinguish cyclin D1-negative MCL from other lymphomas. A 26-miRNA classifier could distinguish MCL from small lymphocytic leukemia/lymphoma, dominated by 23 up-regulated miRNAs in MCL. Unsupervised hierarchical clustering of MCL patients demonstrated a cluster characterized by high expression of miRNAs from the polycistronic miR17-92 cluster and its paralogs, miR-106a-363 and miR-106b-25, and associated with high proliferation gene signature. The other clusters showed enrichment of stroma-associated miRNAs, and also had higher expression of stroma-associated genes. Our clinical outcome analysis in the present study suggested that miRNAs can serve as prognosticators.

A defect of the INK4-Cdk4 checkpoint and Myc collaborate in blastoid mantle cell lymphoma-like lymphoma formation in mice

Mantle cell lymphoma (MCL) is a B-cell malignancy characterized by a monoclonal proliferation of lymphocytes with the co-expression of CD5 and CD43, but not of CD23. Typical MCL is associated with overexpression of cyclin D1, and blastoid MCL variants are associated with Myc (alias c-myc) translocations. In this study, we developed a murine model of MCL-like lymphoma by crossing Cdk4(R24C) mice with Myc-3'RR transgenic mice. The Cdk4(R24C) mouse is a knockin strain that expresses a Cdk4 protein that is resistant to inhibition by p16(INK4a) as well as other INK4 family members. Ablation of INK4 control on Cdk4 does not affect lymphomagenesis, B-cell maturation, and functions in Cdk4(R24C) mice. Additionally, B cells were normal in numbers, cell cycle activity, mitogen responsiveness, and Ig synthesis in response to activation. By contrast, breeding Cdk4(R24C) mice with Myc-3'RR transgenic mice prone to develop aggressive Burkitt lymphoma-like lymphoma (CD19(+)IgM(+)IgD(+) cells) leads to the development of clonal blastoid MCL-like lymphoma (CD19(+)IgM(+)CD5(+)CD43(+)CD23(-) cells) in Myc/Cdk4(R24C) mice. Western blot analysis revealed high amounts of Cdk4/cyclin D1 complexes as the main hallmark of these lymphomas. These results indicate that although silent in nonmalignant B cells, a defect in the INK4-Cdk4 checkpoint can participate in lymphomagenesis in conjunction with additional alterations of cell cycle control, a situation that might be reminiscent of the development of human blastoid MCL.

The impact of cyclin D1 mRNA isoforms, morphology and p53 in mantle cell lymphoma: p53 alterations and blastoid morphology are strong predictors of a high proliferation index

BACKGROUND

Mantle cell lymphoma is a clinically heterogeneous disease characterized by overexpression of cyclin D1 protein. Blastoid morphology, high proliferation, and secondary genetic aberrations are markers of aggressive behavior. Expression profiling of mantle cell lymphoma revealed that predominance of the 3'UTR-deficient, short cyclin D1 mRNA isoform was associated with high cyclin D1 levels, a high "proliferation signature" and poor prognosis.

DESIGN AND METHODS

Sixty-two cases of mantle cell lymphoma were analyzed for cyclin D1 mRNA isoforms and total cyclin D1 levels by real-time reverse transcriptase polymerase chain reaction, and TP53 alterations were assessed by immunohistochemistry and molecular analysis. Results were correlated with proliferation index and clinical outcome.

RESULTS

Predominance of the short cyclin D1 mRNA was found in 14 (23%) samples, including four with complete loss of the standard transcript. TP53 alterations were found in 15 (24%) cases. Predominance of 3'UTR-deficient mRNA was significantly associated with high cyclin D1 mRNA levels (P=0.009) and more commonly found in blastoid mantle cell lymphoma (5/11, P=0.060) and cases with a proliferation index of >20% (P=0.026). Both blastoid morphology (11/11, P<0.001) and TP53 alterations (15/15, P<0.001) were significantly correlated with a high proliferation index. A proliferation index of 10% was determined to be a significant threshold for survival in multivariate analysis (P=0.01).

CONCLUSIONS

TP53 alterations are strongly associated with a high proliferation index and aggressive behavior in mantle cell lymphoma. Predominance of the 3'UTR-deficient transcript correlates with higher cyclin D1 levels and may be a secondary contributing factor to high proliferation, but failed to reach prognostic significance in this study.

CD5-negative blastoid variant mantle cell lymphoma with complex CCND1/IGH and MYC aberrations

The coexistence of CCND1/IGH and MYC rearrangements in mantle cell lymphoma (MCL) is a rare finding associated with a very poor prognosis. In this study, a patient with blastoid variant (MCL) is reported. The disease was clinically aggressive and refractory to chemotherapy, and the patient only survived for 1 month following diagnosis. Conventional cytogenetic study, FISH, and multicolor FISH (mFISH) demonstrated the involvement of the BCL1/CCND1 locus in a complex translocation, t(3;11)(q25;p15)t(11;14)(q13;q32). In addition, subclonal abnormalities in the 8q24 region, manifested as a t(8;14)(q24;q32)/MYC rearrangement, were identified. To the best of our knowledge, this is the first MCL case in Korea bearing these complex genomic aberrations.

The miRNA-17∼92 cluster mediates chemoresistance and enhances tumor growth in mantle cell lymphoma via PI3K/AKT pathway activation

The median survival of patients with mantle cell lymphoma (MCL) ranges from 3 to 5 years with current chemotherapeutic regimens. A common secondary genomic alteration detected in MCL is chromosome 13q31-q32 gain/amplification, which targets a microRNA (miRNA) cluster, miR-17∼92. On the basis of gene expression profiling, we found that high level expression of C13orf25, the primary transcript from which these miRNAs are processed, was associated with poorer survival in patients with MCL (P=0.021). We demonstrated that the protein phosphatase PHLPP2, an important negative regulator of the PI3K/AKT pathway, was a direct target of miR-17∼92 miRNAs, in addition to PTEN and BIM. These proteins were down-modulated in MCL cells with overexpression of the miR-17∼92 cluster. Overexpression of miR-17∼92 activated the PI3K/AKT pathway and inhibited chemotherapy-induced apoptosis in MCL cell lines. Conversely, inhibition of miR-17∼92 expression suppressed the PI3K/AKT pathway and inhibited tumor growth in a xenograft MCL mouse model. Targeting the miR-17∼92 cluster may therefore provide a novel therapeutic approach for patients with MCL.

Small interfering RNAs targeting cyclin D1 and cyclin D2 enhance the cytotoxicity of chemotherapeutic agents in mantle cell lymphoma cell lines

Cyclin D1 (CCND1) is a known cell cycle regulator whose overexpression is a hallmark of mantle cell lymphoma (MCL). Although molecular techniques have unified the diagnostic approach to MCL, no therapeutic advances have been made to target this particular pathway. The significance of CCND1 in the pathogenesis and treatment of MCL has yet to be defined. We have taken advantage of RNA interference (RNAi) to down-regulate CCND1 expression in two MCL cell lines (Granta-519 and Jeko-1) to investigate the cytotoxic effect of combining RNAi with conventional chemotherapeutic agents. We designed four small interfering RNAs (siRNAs) specific to CCND1, one specific to CCND2, and one dual-targeting siRNA that simultaneously down-regulates CCND1 and CCND2. Etoposide and doxorubicin were used as chemotherapeutics in combination with the siRNAs. The transfected siRNAs in MCL cell lines triggered 40-60% reduction in target mRNA and protein levels. Importantly, the siRNA-mediated reduction in cyclins resulted in decreased IC(50) (50% inhibitory concentration) values for both doxorubicin and etoposide. The combination of siRNA-mediated inhibition of the cyclins along with chemotherapeutic agents could potentially be used to lower the effective doses of the chemotherapeutic agents and reduce drug-related toxicities.

Mantle cell lymphoma

MCL is a well-characterized clinically aggressive lymphoma with a poor prognosis. Recent research findings have slightly improved the outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it does not improve overall survival with respect to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidated by ASCT ameliorates response rate and prolongs progression-free survival, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better dissection of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy in most patients and spare the toxicity of intense therapy in a minority of MCL patients characterized by a relatively indolent disease. Patients not eligible for intensive regimens, such as hyperC-VAD, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy for relapsed disease, although there are currently no data to recommend this approach as the first-line strategy. As the optimal approach to the management of MCL is still evolving, it is critical that these patients be enrolled in clinical trials to identify better treatment options.

Virtual CGH: an integrative approach to predict genetic abnormalities from gene expression microarray data applied in lymphoma

Background

Comparative Genomic Hybridization (CGH) is a molecular approach for detecting DNA Copy Number Alterations (CNAs) in tumor, which are among the key causes of tumorigenesis. However in the post-genomic era, most studies in cancer biology have been focusing on Gene Expression Profiling (GEP) but not CGH, and as a result, an enormous amount of GEP data had been accumulated in public databases for a wide variety of tumor types. We exploited this resource of GEP data to define possible recurrent CNAs in tumor. In addition, the CNAs identified by GEP would be more functionally relevant CNAs in the disease pathogenesis since the functional effects of CNAs can be reflected by altered gene expression.

Methods

We proposed a novel computational approach, coined virtual CGH (vCGH), which employs hidden Markov models (HMMs) to predict DNA CNAs from their corresponding GEP data. vCGH was first trained on the paired GEP and CGH data generated from a sufficient number of tumor samples, and then applied to the GEP data of a new tumor sample to predict its CNAs.

Results

Using cross-validation on 190 Diffuse Large B-Cell Lymphomas (DLBCL), vCGH achieved 80% sensitivity, 90% specificity and 90% accuracy for CNA prediction. The majority of the recurrent regions defined by vCGH are concordant with the experimental CGH, including gains of 1q, 2p16-p14, 3q27-q29, 6p25-p21, 7, 11q, 12 and 18q21, and losses of 6q, 8p23-p21, 9p24-p21 and 17p13 in DLBCL. In addition, vCGH predicted some recurrent functional abnormalities which were not observed in CGH, including gains of 1p, 2q and 6q and losses of 1q, 6p and 8q. Among those novel loci, 1q, 6q and 8q were significantly associated with the clinical outcomes in the DLBCL patients (p < 0.05).

Conclusions

We developed a novel computational approach, vCGH, to predict genome-wide genetic abnormalities from GEP data in lymphomas. vCGH can be generally applied to other types of tumors and may significantly enhance the detection of functionally important genetic abnormalities in cancer research.

Mantle cell lymphoma with features of marginal-zone lymphoma

We present seven cases of mantle cell lymphoma with morphological features of marginal-zone lymphoma. Of particular interest, four of the patients had predominant involvement of the gastrointestinal tract. All cases displayed the translocation t(11;14)(q13;q32) and expressed cyclin D1. Cytogenetic analysis revealed trisomy 3 in one case and somatic hypermutation of immunoglobulin heavy genes could be demonstrated in two out of four cases. The latter features are reminiscent of marginal-zone lymphoma. The localization of these lymphomas mainly in the gastrointestinal tract and the higher exposure to antigens in this area may explain why this variant of mantle cell lymphoma harbours features of marginal-zone lymphoma.

Investigational histone deacetylase inhibitors for non-Hodgkin lymphomas

IMPORTANCE OF THE FIELD

Histone deacetylase inhibitors (HDIs) have been shown effective as single agents for cutaneous T-cell lymphomas, peripheral T-cell lymphomas, and B-cell lymphomas, such as follicular lymphoma and mantle cell lymphoma. Of interest, HDIs in combination with other drugs can be a treatment for Epstein-Barr virus-associated lymphoproliferative disorders. Our data of gene expression profiles in PBMCs of responders to vorinostat was discussed.

AREAS COVERED IN THIS REVIEW

This review summarizes recent clinical trials of HDIs in non-Hodgkin lymphomas, the effects of HDIs in in vitro and mouse models, and the possibility of future combination treatments.

WHAT THE READER WILL GAIN

The HDI dosing schedule is crucial to optimize outcomes and avoid irreversible adverse effects. Responses to HDIs are slow, highlighting the need to continue treatment until the maximum response is achieved. HDIs cause hyperacetylation of histone and nonhistone proteins, resulting in various effects on neoplastic cells and immune responses in their microenvironment.

TAKE HOME MESSAGE

Even though HDIs are not potent as single agents, they are likely to provide promising therapeutic options when combined with other agents, i.e., BCL2/BCL-XL antagonists and proteasome inhibitors. Future studies should seek to identify biomarkers that predict patient responses to HDIs.

The essential role of evasion from cell death in cancer

The link between evasion of apoptosis and the development of cellular hyperplasia and ultimately cancer is implicitly clear if one considers how many cells are produced each day and, hence, how many cells must die to make room for the new ones (reviewed in Raff, 1996). Furthermore, cells are frequently experiencing noxious stimuli that can cause lesions in their DNA and faults in DNA replication can occur during cellular proliferation. Such DNA damage needs to be repaired efficiently or cells with irreparable damage must be killed to prevent subsequent division of aberrant cells that may fuel tumorigenesis (reviewed in Weinberg, 2007). The detection of genetic lesions in human cancers that activate prosurvival genes or disable proapoptotic genes have provided the first evidence that defects in programmed cell death can cause cancer (Tagawa et al., 2005; Tsujimoto et al., 1984; Vaux, Cory, and Adams, 1988) and this concept was proven by studies with genetically modified mice (Egle et al., 2004b; Strasser et al., 1990a). It is therefore now widely accepted that evasion of apoptosis is a requirement for both neoplastic transformation and sustained growth of cancer cells (reviewed in Cory and Adams, 2002; Hanahan and Weinberg, 2000; Weinberg, 2007). Importantly, apoptosis is also a major contributor to anticancer therapy-induced killing of tumor cells (reviewed in Cory and Adams, 2002; Cragg et al., 2009). Consequently, a detailed understanding of apoptotic cell death will help to better comprehend the complexities of tumorigenesis and should assist with the development of improved targeted therapies for cancer based on the direct activation of the apoptotic machinery (reviewed in Lessene, Czabotar, and Colman, 2008).

Update on the molecular pathogenesis and clinical treatment of Mantle Cell Lymphoma (MCL): minutes of the 9th European MCL Network conference

Mantle cell lymphoma (MCL) is a distinct subtype of malignant lymphoma which is characterized by the chromosomal translocation t(11;14)(q13;q32), resulting in constitutional overexpression of cyclin D1 and cell cycle dysregulation in virtually all cases. Clinically, MCL shows an aggressive clinical course with a continuous relapse pattern and a median survival of only 3-5 years. However, recently a subset of 15% long-term survivors has been identified with a rather indolent clinical course, even after conventional treatment strategies only. Advanced stage disease is usually apparent already at first clinical manifestation; thus, conventional chemotherapy is only palliative, and the median duration of remissions is only 1-2 years. Emerging strategies including proteasome inhibitors, immune modulatory drugs (IMiDs), mTOR inhibitors, and others are based on the dysregulated control of cell cycle machinery and impaired apoptotic pathways. Monotherapy of these compounds achieves efficacy comparable to conventional chemotherapy in relapsed MCL, and combination strategies are currently being investigated in numerous trials; however, their introduction into clinical practice and current treatment algorithms remain a challenge. In 2000 the European MCL Network ( http://www.european-mcl.net ) was founded, consisting of 15 national lymphoma study groups supplemented by experts in histopathology and molecular genetics. During the past decade, the European consortium has successfully initiated the largest phase III trials in MCL worldwide, with a current annual recruitment of almost 200 patients per year in first-line studies. In detail, in prospective randomized studies, the addition of a B-lymphocyte specific antibody doubled the median progression-free survival from 14 to 28 months, and a dose-intensified consolidation with high-dose radiochemotherapy and subsequent autologous stem cell transplant resulted in superior response duration (3.7 vs. 1.6 years) and even improved overall survival in a recent analysis. Future strategies will apply individualized approaches according to the molecular risk profile of the patient. At the recent annual conference in Jerusalem, recent results of molecular pathogenesis, analyses of current clinical trials, and new study concepts were discussed.

Genome-wide DNA profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome

Marginal zone B-cell lymphomas (MZLs) have been divided into 3 distinct subtypes (extranodal MZLs of mucosa-associated lymphoid tissue [MALT] type, nodal MZLs, and splenic MZLs). Nevertheless, the relationship between the subtypes is still unclear. We performed a comprehensive analysis of genomic DNA copy number changes in a very large series of MZL cases with the aim of addressing this question. Samples from 218 MZL patients (25 nodal, 57 MALT, 134 splenic, and 2 not better specified MZLs) were analyzed with the Affymetrix Human Mapping 250K SNP arrays, and the data combined with matched gene expression in 33 of 218 cases. MALT lymphoma presented significantly more frequently gains at 3p, 6p, 18p, and del(6q23) (TNFAIP3/A20), whereas splenic MZLs was associated with del(7q31), del(8p). Nodal MZLs did not show statistically significant differences compared with MALT lymphoma while lacking the splenic MZLs-related 7q losses. Gains of 3q and 18q were common to all 3 subtypes. del(8p) was often present together with del(17p) (TP53). Although del(17p) did not determine a worse outcome and del(8p) was only of borderline significance, the presence of both deletions had a highly significant negative impact on the outcome of splenic MZLs.

MicroRNA-17-92 significantly enhances radioresistance in human mantle cell lymphoma cells

The microRNA-17-92 (miRNA-17-92) cluster, at chromosome 13q31-q32, also known as oncomir-1, consists of seven miRNAs that are transcribed as a polycistronic unit. Over-expression of miRNA-17-92 has been observed in lymphomas and other solid tumors. Whether miRNA-17-92 expression affects the response of tumor cells to radiotherapy is not addressed so far. In the present study, we studied the effects of miRNA-17-92 on the radiosensitivity of human mantle cell lymphoma (MCL) cells Z138c. Over-expression of miRNA-17-92 significantly increased survival cell number, cell proliferation and decreased cell death of human MCL cells after different doses of radiation. Immunoblot analysis showed that phosphatase and tension homolog (PTEN) and PHLPP2 was down-modulated and pAkt activity was enhanced in MCL cells after over-expressing miRNA-17-92 after irradiation. These findings are the first direct evidence that over-expression of miRNA-17-92 cluster significantly increases the radioresistance of human MCL cells, which offers a novel target molecule for improving the radiotherapy of MCL in clinic.

Incidence and prognostic impact of secondary cytogenetic aberrations in a series of 145 patients with mantle cell lymphoma

Mantle cell lymphoma (MCL) is a mature B-cell neoplasm with an aggressive behavior, characterized by the t(11;14)(q13;q32). Several secondary genetic abnormalities with a potential role in the oncogenic process have been described. Studies of large MCL series using conventional cytogenetics, and correlating with proliferation and survival, are scarce. We selected 145 MCL cases at diagnosis, displaying an aberrant karyotype, from centers belonging to the Spanish Cooperative Group for Hematological Cytogenetics. Histological subtype, proliferative index and survival data were ascertained. Combined cytogenetic and molecular analyses detected CCND1 translocations in all cases, mostly t(11;14)(q13;q32). Secondary aberrations were present in 58% of patients, the most frequent being deletions of 1p, 13q and 17p, 10p alterations and 3q gains. The most recurrent breakpoints were identified at 1p31-32, 1p21-22, 17p13, and 1p36. Aggressive blastoid/pleomorphic variants displayed a higher karyotypic complexity, a higher frequency of 1p and 17p deletions and 10p alterations, a higher proliferation index and poor survival. Gains of 3q and 13q and 17p13 losses were associated with reduced survival times. Interestingly, gains of 3q and 17p losses added prognostic significance to the morphology in a multivariate analysis. Our findings confirm previous observations indicating that proliferation index, morphology and several secondary genetic alterations (3q gains and 13q and 17p losses) have prognostic value in patients with MCL. Additionally, we observed that 3q gains and 17p losses detected by conventional cytogenetics are proliferation-independent prognostic markers indicating poor outcome.

Mantle cell lymphoma: transcriptional regulation by microRNAs

Mantle cell lymphoma (MCL) pathogenesis is still partially unexplained. We investigate the importance of microRNA (miRNA) expression as an additional feature that influences MCL pathway deregulation and may be useful for predicting patient outcome. Twenty-three MCL samples, eight cell lines and appropriate controls were screened for their miRNAs and gene expression profiles and DNA copy-number changes. MCL patients exhibit a characteristic signature that includes 117 miRNA (false discovery rate <0.05). Combined analysis of miRNAs and the gene expression profile, paired with bioinformatics target prediction (miRBase and TargetScan), revealed a series of genes and pathways potentially targeted by a small number of miRNAs, including essential pathways for lymphoma survival such as CD40, mitogen-activated protein kinase and NF-kappaB. Functional validation in MCL cell lines demonstrated NF-kappaB subunit nuclear translocation to be regulated by the expression of miR-26a. The expression of 12 selected miRNAs was studied by quantitative PCR in an additional series of 54 MCL cases. Univariate analysis identified a single miRNA, miR-20b, whose lack of expression distinguished cases with a survival probability of 56% at 60 months. In summary, using a novel bioinformatics approach, this study identified miRNA changes that contribute to MCL pathogenesis and markers of potential utility in MCL diagnosis and clinical prognostication.

Pathway discovery in mantle cell lymphoma by integrated analysis of high-resolution gene expression and copy number profiling

The genome of mantle cell lymphoma (MCL) is, in addition to the translocation t(11;14), characterized by a high number of secondary chromosomal gains and losses that probably account for the various survival times of MCL patients. We investigated 77 primary MCL tumors with available clinical information using high-resolution RNA expression and genomic profiling and applied our recently developed gene expression and dosage integrator algorithm to identify novel genes and pathways that may be of relevance for the pathobiology of MCL. We show that copy number neutral loss of heterozygosity is common in MCL and targets regions that are frequently affected by deletions. The molecular consequences of genomic copy number changes appear complex, even in genomic loci with identified tumor suppressors, such as the region 9p21 containing the CDKN2A locus. Moreover, the deregulation of novel genes, such as CUL4A, ING1, and MCPH1, may affect the 2 crucial pathogenetic mechanisms in MCL, the disturbance of the proliferation, and DNA damage response pathways. Deregulation of the Hippo pathway may have a pathogenetic role in MCL because decreased expression of its members MOBKL2A, MOBKL2B, and LATS2 was associated with inferior outcome, including an independent validation series of 32 MCLs.

Mantle cell lymphoma: biological insights and treatment advances

Mantle cell lymphoma (MCL) exhibits considerable molecular heterogeneity and complexity, and is regarded as one of the most challenging lymphomas to treat. With increased understanding of the pathobiology of MCL, it is proposed that MCL is the result of 3 major converging factors, namely, deregulated cell cycle pathways, defects in DNA damage responses, and dysregulation of cell survival pathways. In the present era of targeted therapies, these biologic insights have resulted in the identification of several novel rational targets for therapeutic intervention in MCL that are undergoing active clinical testing. To date, there is no standard of care in MCL. Several approaches including conventional anthracycline-based therapies and intensive high-dose strategies with and without stem cell transplantation have failed to produce durable remissions for most patients. Moreover, considering the heterogeneity of MCL, it is increasingly being recognized that risk-adapted therapy might be a relevant therapeutic approach in this disease. At the first and second Global Workshops on Mantle Cell Lymphoma, questions addressing advances in the pathobiology of MCL, optimization of existing therapies, assessment of current data with novel therapeutic strategies, and the identification of molecular or phenotypic risk factors for utilization in risk-adapted therapies were discussed and will be summarized herein.

SOX11 expression is highly specific for mantle cell lymphoma and identifies the cyclin D1-negative subtype

BACKGROUND

Cyclin D1-negative mantle cell lymphoma is difficult to distinguish from other small B-cell lymphomas. The clinical and pathological characteristics of patients with this form of lymphoma have not been well defined. Overexpression of the transcription factor SOX11 has been observed in conventional mantle cell lymphoma. The aim of this study was to determine whether this gene is expressed in cyclin D1-negative mantle cell lymphoma and whether its detection may be useful to identify these tumors.

DESIGN AND METHODS

The microarray database of 238 mature B-cell neoplasms was re-examined. SOX11 protein expression was investigated immunohistochemically in 12 cases of cyclin D1-negative mantle cell lymphoma, 54 cases of conventional mantle cell lymphoma, and 209 additional lymphoid neoplasms.

RESULTS

SOX11 mRNA was highly expressed in conventional and cyclin D1-negative mantle cell lymphoma and in 33% of the cases of Burkitt's lymphoma but not in any other mature lymphoid neoplasm. SOX11 nuclear protein was detected in 50 cases (93%) of conventional mantle cell lymphoma and also in the 12 cyclin D1-negative cases of mantle cell lymphoma, the six cases of lymphoblastic lymphomas, in two of eight cases of Burkitt's lymphoma, and in two of three T-prolymphocytic leukemias but was negative in the remaining lymphoid neoplasms. Cyclin D2 and D3 mRNA levels were significantly higher in cyclin D1-negative mantle cell lymphoma than in conventional mantle cell lymphoma but the protein expression was not discriminative. The clinico-pathological features and outcomes of the patients with cyclin D1-negative mantle cell lymphoma identified by SOX11 expression were similar to those of patients with conventional mantle cell lymphoma.

CONCLUSIONS

SOX11 mRNA and nuclear protein expression is a highly specific marker for both cyclin D1-positive and negative mantle cell lymphoma.

Integrative oncogenomic analysis of microarray data in hematologic malignancies

During the last decade, gene expression microarrays and array-based comparative genomic hybridization (array-CGH) have unraveled the complexity of human tumor genomes more precisely and comprehensively than ever before. More recently, the simultaneous assessment of global changes in messenger RNA (mRNA) expression and in DNA copy number through "integrative oncogenomic" analyses has allowed researchers the access to results uncovered through the analysis of one-dimensional data sets, thus accelerating cancer gene discovery. In this chapter, we discuss the major contributions of DNA microarrays to the study of hematological malignancies, focusing on the integrative oncogenomic approaches that correlate genomic and transcriptomic data. We also present the basic aspects of these methodologies and their present and future application in clinical oncology.

Molecular diagnosis of hematopoietic and lymphoid neoplasms

This chapter summarizes the significance and molecular diagnostic detection of genetic abnormalities commonly associated with hematolymphoid neoplasms. Methodologic aspects of laboratory diagnosis are presented, as well as discussion of multiparameter genotyping of tumors for prognosis and the role of minimal residual disease monitoring in specific neoplasms.

MicroRNA expression, chromosomal alterations, and immunoglobulin variable heavy chain hypermutations in Mantle cell lymphomas

The contribution of microRNAs (miR) to the pathogenesis of mantle cell lymphoma (MCL) is not well known. We investigated the expression of 86 mature miRs mapped to frequently altered genomic regions in MCL in CD5(+)/CD5(-) normal B cells, reactive lymph nodes, and purified tumor cells of 17 leukemic MCL, 12 nodal MCL, and 8 MCL cell lines. Genomic alterations of the tumors were studied by single nucleotide polymorphism arrays and comparative genomic hybridization. Leukemic and nodal tumors showed a high number of differentially expressed miRs compared with purified normal B cells, but only some of them were commonly deregulated in both tumor types. An unsupervised analysis of miR expression profile in purified leukemic MCL cells revealed two clusters of tumors characterized by different mutational status of the immunoglobulin genes, proliferation signature, and number of genomic alterations. The expression of most miRs was not related to copy number changes in their respective chromosomal loci. Only the levels of miRs included in the miR-17-92 cluster were significantly related to genetic alterations at 13q31. Moreover, overexpression of miR-17-5p/miR-20a from this cluster was associated with high MYC mRNA levels in tumors with a more aggressive behavior. In conclusion, the miR expression pattern of MCL is deregulated in comparison with normal lymphoid cells and distinguishes two subgroups of tumors with different biological features.

Gene knockdown studies revealed CCDC50 as a candidate gene in mantle cell lymphoma and chronic lymphocytic leukemia

The two B-cell non-Hodgkin's lymphoma entities, chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), show recurrent chromosomal gains of 3q25-q29, 12q13-q14 and 18q21-q22. The pathomechanisms affected by these aberrations are not understood. The aim of this study was to identify genes, located within these gained regions, which control cell death and cell survival of MCL and CLL cancer cells. Blood samples collected from 18 patients with CLL and 6 patients with MCL, as well as 6 cell lines representing both malignancies were analyzed by gene expression profiling. By a comparison of genomic DNA and gene expression, 72 candidate genes were identified. We performed a limited RNA interference screening with these candidates to identify genes affecting cell survival. CCDC50 (coiled coil domain containing protein 50), SERPINI2 and SMARCC2 mediated a reduction of cell viability in primary CLL cells as well as in cell lines. Gene knockdown and a nuclear factor kappa B (NFkappaB) reporter gene assay revealed that CCDC50 is required for survival in MCL and CLL cells and controls NFkappaB signaling.

CD5 negative, Cyclin D1-positive diffuse large B-cell lymphoma (DLBCL) presenting as ruptured spleen

We present a case of diffuse large B-cell lymphoma CD5 negative, Cyclin D1 positive presenting as ruptured spleen in a 63-year-old man requiring emergent splenectomy. Tumor cells showed marked pleomorphism, anaplasia, and increased mitotic figures with positive Cyclin D1, BCL6, MUM1, P53, and a high MIB1 proliferative fraction. The patient received multiple therapies and ultimately died. This case raises the differential diagnoses of pleomorphic mantle cell lymphoma and other aggressive lymphomas with pleomorphic, anaplastic, and Reed-Sternberg-like cells.

Cyclin D1 expression in typical chronic lymphocytic leukaemia

Demonstration of cyclin D1 expression by immunohistochemistry in a CD5-positive small B-cell proliferation is extremely helpful in the diagnosis of mantle cell lymphoma in tissue samples, including bone marrow trephine biopsies (BMTB) and in differentiating them from chronic lymphocytic leukaemia (CLL). Following the identification of cyclin D1 expression in one case of CLL on BMTB, 64 additional cases, which included 25 lymph nodes, one tonsillar lesion, one skin lesion and 37 BMTBs were systematically reviewed for presence of cyclin D1 overexpression. Overall, in seven of 65 samples (approximately 10%) of CLL, a minority of the leukaemic cells in the proliferation centres expressed cyclin D1. Cytogenetic analysis had been performed in three of seven cases and there was no evidence of translocation involving CCND1 locus. Our findings suggest that a small subset of CLL overexpresses cyclin D1 in amounts that can be demonstrated by immunohistochemistry. Our observation has impact on the diagnosis of small B-cell lymphomas in BMTB and other tissue samples.

Molecular outcome prediction in mantle cell lymphoma

Mantle cell lymphoma (MCL), a subtype of B-cell non-Hodgkin lymphoma, is usually incurable with current therapeutic approaches and the clinical course displays considerable variability. Objective assessment of the efficacy of new and more tailored treatment strategies requires deeper molecular insights into the disease and more individual risk assessment. The molecular feature of tumor cell proliferation as measured by Ki-67 immunohistochemistry or, more precisely, by microarray-based gene-expression profiling, has been shown to be of strong predictive value in MCL. The recently proposed quantitative reverse transcription-PCR based five-gene model survival predictor is applicable to fresh-frozen and routinely obtained formalin-fixed and paraffin-embedded tumor tissues, and provides the potential to investigate its prognostic value in prospective clinical trials of MCL patients.

Outcome of deferred initial therapy in mantle-cell lymphoma

PURPOSE

Treatment of mantle-cell lymphoma (MCL) is nonstandardized, though patients are commonly treated immediately at diagnosis. Because data on observation, or "watch and wait," have not been previously reported, we analyzed the outcome of deferred initial therapy.

PATIENTS AND METHODS

Inclusion criteria in this retrospective analysis were a diagnosis of MCL between 1997 and 2007 and known date of first treatment. Hospital and research charts were reviewed for prognostic and treatment-related information. Date of death was derived from hospital records and confirmed using an online Social Security death index.

RESULTS

Of 97 patients with MCL evaluated at Weill Cornell Medical Center, 31 patients (32%) were observed for more than 3 months before initial systemic therapy, with median time to treatment for the observation group of 12 months (range, 4 to 128 months). The observation group (median follow-up, 55 months) had a median age of 58 years (range, 40 to 81 years). Prognostic factors in assessable patients included advanced stage (III/IV) in 75%, elevated lactate dehydrogenase in 25%, and intermediate- or high-risk Mantle Cell International Prognostic Index in 54%. Better performance status and lower-risk standard International Prognostic Index scores were more commonly present in those undergoing observation. Although time to treatment did not predict overall survival in a multivariate analysis, the survival profile of the observation group was statistically superior to that of the early treatment group (not reached v 64 months, P = .004).

CONCLUSION

In selected asymptomatic patients with MCL, deferred initial treatment ("watch and wait") is an acceptable management approach.