Characterization of D-cyclin proteins in hematolymphoid neoplasms: lack of specificity of cyclin-D2 and D3 expression in lymphoma subtypes

Transcriptomic changes including p53 dysregulation prime DNMT3A mutant cells for transformation

DNMT3A mutations are prevalent in haematologic malignancies. In our mouse model the murine homologue (R878H) of the human 'hotspot' R882H mutation is introduced into the mouse Dnmt3a locus. This results in globally reduced DNA methylation in all tissues. Mice with heterozygous R878H DNMT3A mutations develop γ-radiation induced thymic lymphoma more rapidly than control mice, suggesting a vulnerability to stress stimuli in Dnmt3aR878H/+ cells. In competitive transplantations, Dnmt3aR878H/+ Lin-Sca-1+Kit+ (LSK) haematopoietic stem/progenitor cells (HSPCs) have a competitive advantage over WT HSPCs, indicating a self-renewal phenotype at the expense of differentiation. RNA sequencing of Dnmt3aR878H/+ LSKs exposed to low dose γ-radiation shows downregulation of the p53 pathway compared to γ-irradiated WT LSKs. Accordingly, reduced PUMA expression is observed by flow cytometry in the bone marrow of γ-irradiated Dnmt3aR878H/+ mice due to impaired p53 signalling. These findings provide new insights into how DNMT3A mutations cause subtle changes in the transcriptome of LSK cells which contribute to their increased self-renewal and propensity for malignant transformation.

Cyclin D1-negative mantle cell lymphoma

Cyclin D1-negative mantle cell lymphoma (MCL) is regarded as a B-cell neoplasm that has morphologic and immunophenotypic findings indistinguishable from typical MCL. These neoplasms lack cyclin D1 overexpression by immunohistochemistry and t(11;14)(q13;q32)/IGH::CCND1. Since cyclin D1-negative MCL was first recognized by gene expression profiling in 2003, there has been diagnostic confusion regarding this entity, mostly attributable to a lack of diagnostic tools to recognize these neoplasms in most clinical laboratories. Accumulated data show that most cyclin D1-negative MCL cases harbor CCND2 or CCND3 translocation with a variety of gene partners. In this review, the concept of cyclin D1-negative MCL is discussed in chronological order to further our understanding of this entity. We then discuss currently available diagnostic approaches and we conclude with future directions. We also suggest that the more specific terms CCND2-rearranged MCL or CCND3-rearranged MCL be used for neoplasms in which the rearranged gene is known, and that we reserve the term cyclin D1-negative MCL for neoplasms in which the rearranged gene in unknown.

Post-GWAS Validation of Target Genes Associated with HbF and HbA2 Levels

Genome-Wide Association Studies (GWASs) have identified a huge number of variants associated with different traits. However, their validation through in vitro and in vivo studies often lags well behind their identification. For variants associated with traits or diseases of biomedical interest, this gap delays the development of possible therapies. This issue also impacts beta-hemoglobinopathies, such as beta-thalassemia and sickle cell disease (SCD). The definitive cures for these diseases are currently bone marrow transplantation and gene therapy. However, limitations regarding their effective use restrict their worldwide application. Great efforts have been made to identify whether modulators of fetal hemoglobin (HbF) and, to a lesser extent, hemoglobin A2 (HbA2) are possible therapeutic targets. Herein, we performed the post-GWAS in vivo validation of two genes, cyclin D3 (CCND3) and nuclear factor I X (NFIX), previously associated with HbF and HbA2 levels. The absence of Ccnd3 expression in vivo significantly increased g (HbF) and d (HbA2) globin gene expression. Our data suggest that CCND3 is a possible therapeutic target in sickle cell disease. We also confirmed the association of Nfix with γ-globin gene expression and present data suggesting a possible role for Nfix in regulating Kruppel-like transcription factor 1 (Klf1), a master regulator of hemoglobin switching. This study contributes to filling the gap between GWAS variant identification and target validation for beta-hemoglobinopathies.

Identification and validation of hub genes in CD5-positive diffuse large B-cell lymphoma

CD5+ diffuse large B-cell lymphoma (DLBCL), as a significant heterogeneity category of DLBCL, is reflected in both the molecular biological and genetic levels, which in turn induces ever-changing clinical manifestations, and what mediates tumor survival mechanisms are still unclear. This study aimed to predict the potential hub genes in CD5+ DLBCL. A total of 622 patients with DLBCL diagnosed between 2005 and 2019 were included. High expression of CD5 was correlated with IPI, LDH, and Ann Arbor stage, patients with CD5-DLBCL have longer overall survival. We identified 976 DEGs between CD5-negative and positive DLBCL patients in the GEO database and performed GO and KEGG enrichment analysis. After intersecting the genes obtained through the Cytohubba and MCODE, further external verification was performed in the TCGA database. Three hub genes were screened: VSTM2B, GRIA3, and CCND2, of which CCND2 were mainly involved in cell cycle regulation and JAK-STAT signaling pathways. Analysis of clinical samples showed that the expression of CCND2 was found to be correlated with CD5 (p = 0.001), and patients with overexpression of CCND2 in CD5+ DLBCL had poor prognosis (p = 0.0455). Cox risk regression analysis showed that, for DLBCL, CD5, and CCND2 double positive was an independent poor prognostic factor (HR: 2.545; 95% CI: 1.072-6.043; p = 0.034). These findings demonstrate that CD5 and CCND2 double-positive tumors should be stratified into specific subgroups of DLBCL with poor prognosis. CD5 may regulate CCND2 through JAK-STAT signaling pathways, mediating tumor survival. This study provides independent adverse prognostic factors for risk assessment and treatment strategies for newly diagnosed DLBCL.

Short-Term TERT Inhibition Impairs Cellular Proliferation via a Telomere Length-Independent Mechanism and Can Be Exploited as a Potential Anticancer Approach

Telomerase reverse transcriptase (TERT), the catalytic component of telomerase, may also contribute to carcinogenesis via telomere-length independent mechanisms. Our previous in vitro and in vivo studies demonstrated that short-term telomerase inhibition by BIBR1532 impairs cell proliferation without affecting telomere length. Here, we show that the impaired cell cycle progression following short-term TERT inhibition by BIBR1532 in in vitro models of B-cell lymphoproliferative disorders, i.e., Epstein-Barr virus (EBV)-immortalized lymphoblastoid cell lines (LCLs), and B-cell malignancies, i.e., Burkitt's lymphoma (BL) cell lines, is characterized by a significant reduction in NF-κB p65 nuclear levels leading to the downregulation of its target gene MYC. MYC downregulation was associated with increased expression and nuclear localization of P21, thus promoting its cell cycle inhibitory function. Consistently, treatment with BIBR1532 in wild-type zebrafish embryos significantly decreased Myc and increased p21 expression. The combination of BIBR1532 with antineoplastic drugs (cyclophosphamide or fludarabine) significantly reduced xenografted cells' proliferation rate compared to monotherapy in the zebrafish xenograft model. Overall, these findings indicate that short-term inhibition of TERT impairs cell growth through the downregulation of MYC via NF-κB signalling and supports the use of TERT inhibitors in combination with antineoplastic drugs as an efficient anticancer strategy.

Cyclin D degradation by E3 ligases in cancer progression and treatment

D cyclins include three isoforms: D1, D2, and D3. D cyclins heterodimerize with cyclin-dependent kinase 4/6 (CDK4/6) to form kinase complexes that can phosphorylate and inactivate Rb. Inactivation of Rb triggers the activation of E2F transcription factors, which in turn regulate the expression of genes whose products drive cell cycle progression. Because D-type cyclins function as mitogenic sensors that link growth factor signaling directly with G₁ phase progression, it is not surprising that D cyclin accumulation is dysregulated in a variety of human tumors. Elevated expression of D cyclins results from gene amplification, increased gene transcription and protein translation, decreased microRNA levels, and inefficiency or loss of ubiquitylation-mediated protein degradation. This review focuses on the clinicopathological importance of D cyclins, how dysregulation of Ubiquitin-Proteasome System (UPS) contributes to the overexpression of D cyclins, and the therapeutic potential through targeting D cyclin-related machinery in human tumors.

Human bone marrow-derived mesenchymal stem cells promote the growth and drug-resistance of diffuse large B-cell lymphoma by secreting IL-6 and elevating IL-17A levels

Background

The drug-resistance and relapse of diffuse large B-cell lymphoma (DLBCL), which are related to mesenchymal stem cells (MSCs), have become increasingly common. However, the underlying mechanisms remain elusive.

Methods

CCK 8 assay, colony formation assay, and xenograft mouse model were used to investigate the effects of hBMSCs on DLBCL growth. Immunohistochemistry, qRT-PCR, and ELISA were used to study the expressions of IL-6 and IL-17A. Flow cytometry was used to analyze Th17 cells and Treg cells expressions. Western blot analysis, microarray analysis, and bioinformatics analysis were used to analyze the pathways of IL-6 or IL-17A mediated DLBCL growth.

Results

HBMSCs promoted DLBCL growth by secreting IL-6 in vitro and in vivo and simultaneously upregulating IL-17A in vitro. IL-6 and IL-17A synergistically promoted the growth and drug-resistance of DLBCL cells by protecting them from spontaneous or drug-induced apoptosis in vitro. IL-6 or IL-17A activated the JAK2/STAT3 pathway or upregulated cyclin D2 via activation of PI3K/Akt signaling in vitro, respectively.

Conclusions

The present results indicated that hBMSCs might have a “dual effect” on promoting DLBCL progression and drug-resistance by secreting IL-6 and upregulating IL-17A. IL-6, IL-17A, p-STAT3, p-Akt or cyclin D2 may be potential molecular targets for overcoming drug-resistance in patients with relapsed or refractory DLBCL.

Toward a Risk-Tailored Therapeutic Policy in Mantle Cell Lymphoma

PURPOSE OF REVIEW

Mantle cell lymphoma (MCL) prognosis is strictly related to the characteristics of the disease, which can range from very indolent cases to highly aggressive and refractory ones. Here we will review the current knowledge on MCL biomarkers.

RECENT FINDINGS

Biomarker-informed diagnosis is essential for differentiating MCL from other mature B cell tumors. Diagnosis of MCL relies on the identification of the t(11;14) translocation by FISH or the consequently aberrant expression of cyclin D1 by immunohistochemistry. For the few cases staining negative for cyclin D1, SOX11 may help to define the diagnosis. Prognostic biomarkers have been proposed to stratify MCL patients, including baseline clinical aspects (leukemic non-nodal presentation, in situ presentation, Mantle cell International Prognostic Index-MIPI), pathological aspects (blastoid morphology, Ki-67 proliferation index, SOX11 expression), genetic aspects (immunoglobulin gene mutation status, TP53 deletion or mutation, CDKN2A deletion), and depth of response after treatment (PET imaging, molecular minimal residual disease). Such tools are increasingly used as a guide for therapeutic decisions. Watchful waiting approach is recommended for patients harboring favorable clinico-biological features, such as leukemic non-nodal presentation, low MIPI score, non-blastoid disease, low Ki-67 proliferation rate, mutated immunoglobulin genes, and the lack of SOX11 expression. For patients in need of frontline therapy, the decision of whether to undertake intensive regimens is based upon patient's age and comorbidities. Central nervous system prophylaxis is recommended for cases showing blastoid morphology. The duration of remission is tightly correlated to the depth of response. With the aim of achieving a longer duration of remission and survival, younger patients may pursue more intensive regimens incorporating high-dose cytarabine, followed by myeloablative consolidation chemotherapy, autologous stem cell transplantation, and rituximab maintenance. Older patients could, on the other hand, benefit from lower intensity immunochemotherapy followed or not by a maintenance therapy depending on which frontline regimen is used. Despite the identification of several potential useful biomarkers that may inform the treatment decisions and the design of clinical trials, the treatment choice remains nowadays determined by the patient age and fitness rather than by the individual patient characteristics. Tailoring therapy toward a risk-adapted strategy to accommodate the wide spectrum of disease is an urgent challenge, and clinical trials may explore the feasibility of a biomarker-defined therapeutic policy.

Diagnostic Algorithm of Common Mature B-Cell Lymphomas by Immunohistochemistry

CONTEXT

- Different types of mature B-cell lymphomas, including plasma cell neoplasms, exhibit distinct immunohistochemical profiles, which enable them to be correctly diagnosed. However, except for rare examples of lymphoma-specific immunohistochemistry, such as cyclin D1 in mantle cell lymphoma and annexin A1 in hairy cell leukemia, immunohistochemical profiles of mature B-cell lymphomas overlap and lack specificity.

OBJECTIVES

- To systemically review immunohistochemical features associated with commonly encountered mature B-cell lymphomas based on the presence or absence of CD5 and CD10; to review the immunophenotypic profile of plasma cells derived from plasma cell myelomas and B-cell lymphomas; and to review a group of rare, aggressive B-cell lymphomas with antigen expression features of plasma cells.

DATA SOURCES

- Published and PubMed-indexed English literature was reviewed.

CONCLUSIONS

- Although the presence or absence of CD5 and CD10 expression should be included in the initial immunohistochemistry screening panel for mature B-cell lymphomas, appropriate and judicial use of other B-cell antigens is necessary to ensure correct diagnoses. Furthermore, although the status of CD5 and CD10 expression is associated with certain prototypes of B-cell lymphomas, their expression is not specific. Plasma cells from plasma cell neoplasias and B-cell lymphomas exhibit overlapping but relatively distinct immunophenotypes; thus, a panel of immunohistochemical markers (CD19, CD45, CD56, and CD117) can be employed for their proper identification. Lastly, CD138 staining results are almost always positive in a group of aggressive B-cell lymphomas with plasmablastic features, including plasmablastic plasma cell myeloma, plasmablastic lymphoma, and ALK-1⁺ large B-cell lymphoma.

Cyclin D1 expression in peripheral T-cell lymphomas

Cyclin D1 is an important regulator of the cell cycle and overexpression of this protein by immunohistochemistry is characteristically seen in mantle cell lymphoma and other B-cell neoplasms. However, little is known about the expression of this protein in T-cell lymphomas. Cyclin-dependent kinase pathway inhibitors are in development, therefore identifying cyclin D1-positive T-cell lymphomas may provide a therapeutic target in a disease where novel treatments are urgently needed. We collected 200 peripheral T-cell lymphomas from three institutions including the following types of cases: 34 anaplastic large cell lymphoma, ALK+, 44 anaplastic large cell lymphoma, ALK negative, 68 peripheral T-cell lymphomas, not otherwise specified, 24 angioimmunoblastic T-cell lymphomas, 7 extranodal NK/T-cell lymphomas, 4 enteropathy associated T-cell lymphomas, 3 hepatosplenic T-cell lymphomas, 12 cutaneous T-cell lymphomas, and 4 large granular lymphocytic leukemias. Immunohistochemical stains for cyclin D1 protein (SP4 clone) were performed on paraffin-embedded tissue. In a subset of cases, IGH/CCND1 fluorescence in situ hybridization analysis was also performed. Cyclin D1 staining was predominantly seen in anaplastic large cell lymphoma, including 8 of 34 cases with ALK+ anaplastic large cell lymphoma (24%), and 3 of 44 cases of ALK-negative (7%) anaplastic large cell lymphoma. Three cases of peripheral T-cell lymphoma, not otherwise specified, were also positive (3/68, 4%). All other T-cell lymphomas were negative for cyclin D1. In four of the cyclin D1-positive T-cell lymphomas by immunohistochemistry, fluorescence in situ hybridization analysis was negative for IGH/CCND1 translocation or extra copies of the CCND1 gene. Cyclin D1 overexpression by immunohistochemistry is not limited to B-cell lymphomas and is also observed in some peripheral T-cell lymphomas, particularly in anaplastic large cell lymphoma, ALK+. Cyclin D1 expression was not associated with extra copies or translocation of the CCND1 gene. Cyclin D1 overexpression may be the result of a post-translational phenomenon and may represent a potential therapeutic target using agents that target the cyclin-dependent kinase pathway.

Expression of D-type cyclins in mantle cell and diffuse large B-cell lymphomas

D-type cyclins are involved in cell cycle regulation and play an important role in the pathogenesis of lymphomas. Aberrant expression of cyclin D1 is associated with mantle cell lymphoma (MCL) and serves as a diagnostic marker of MCL. Analysis of cyclin D expression in tumor tissues of patients with diffuse large B-cell lymphoma (DLBCL) which comprises a heterogeneous group of tumors may contribute to their stratification. We analyzed expression of cyclin D1, D2, and D3 mRNAs in 30 MCL and 104 DLBCL patients using qRT-PCR and addressed their significance for disease outcome. We confirmed a high level of cyclin D1 mRNA in 29 MCL cases (97%). One case (3%) was identified as positive for cyclin D2. Expression of cyclin D1 was limited to MCL and did not occur in DLBCL. Overexpression of cyclin D2, which is rare in MCL, occurred more frequently in DLBCL (11 cases, 10.6%). We showed that high expression of cyclin D2 in DLBCL cases de novo decreased the overall survival rate (P=0.016) and progression-free survival (P=0.009). The expression pattern of cyclin D3 was similar in both types of studied lymphomas and it did not affect the disease outcome.

Reduced expression of the retinoblastoma protein shows that the related signaling pathway is essential for mediating the antineoplastic activity of erufosine

Erufosine is a new antineoplastic agent of the group of alkylphosphocholines, which interferes with signal transduction and induces apoptosis in various leukemic and tumor cell lines. The present study was designed to examine for the first time the mechanism of resistance to erufosine in malignant cells with permanently reduced expression of the retinoblastoma (Rb) protein. Bearing in mind the high number of malignancies with reduced level of this tumor-suppressor, this investigation was deemed important for using erufosine, alone or in combination, in patients with compromised RB1 gene expression. For this purpose, clones of the leukemic T-cell line SKW-3 were used, which had been engineered to constantly express differently low Rb levels. The alkylphosphocholine induced apoptosis, stimulated the expression of the cyclin dependent kinase inhibitor p27^Kip1 and inhibited the synthesis of cyclin D3, thereby causing a G₂ phase cell cycle arrest and death of cells with wild type Rb expression. In contrast, Rb-deficiency impeded the changes induced by eru-fosine in the expression of these proteins and abrogated the induction of G₂ arrest, which was correlated with reduced antiproliferative and anticlonogenic activities of the compound. In conclusion, analysis of our results showed for the first time that the Rb signaling pathway is essential for mediating the antineoplastic activity of erufosine and its efficacy in patients with malignant diseases may be predicted by determining the Rb status.

Prevalence and clinical implications of cyclin D1 expression in diffuse large B-cell lymphoma (DLBCL) treated with immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program

BACKGROUND

Cyclin D1 expression has been reported in a subset of patients with diffuse large B-cell leukemia (DLBCL), but studies have been few and generally small, and they have demonstrated no obvious clinical implications attributable to cyclin D1 expression.

METHODS

The authors reviewed 1435 patients who were diagnosed with DLBCL as part of the International DLBCL rituximab with cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) Consortium Program and performed clinical, immunohistochemical, and genetic analyses with a focus on cyclin D1. All patients who were cyclin D1-positive according to immunohistochemistry were also assessed for rearrangements of the cyclin D1 gene (CCND1) using fluorescence in situ hybridization. Gene expression profiling was performed to compare patients who had DLBCL with and without cyclin D1 expression.

RESULTS

In total, 30 patients (2.1%) who had DLBCL that expressed cyclin D1 and lacked CCND1 gene rearrangements were identified. Patients with cyclin D1-positive DLBCL had a median age of 57 years (range, 16.0-82.6 years). There were 23 males and 7 females. Twelve patients (40%) had bulky disease. None of them expressed CD5. Two patients expressed cyclin D2. Gene expression profiling indicated that 17 tumors were of the germinal center type, and 13 were of the activated B-cell type. Genetic aberrations of B-cell leukemia/lymphoma 2 (BCL2), BCL6, v-myc avian myelocytomatosis viral oncogene homolog (MYC), mouse double minute 2 oncogene E3 ubiquitin protein ligase (MDM2), MDM4, and tumor protein 53 (TP53) were rare or absent. Gene expression profiling did not reveal any striking differences with respect to cyclin D1 in DLBCL.

CONCLUSIONS

Compared with patients who had cyclin D1-negative DLBCL, men were more commonly affected with cyclin D1-positive DLBCL, and they were significantly younger. There were no other significant differences in clinical presentation, pathologic features, overall survival, or progression-free survival between these two subgroups of patients with DLBCL.

De novo CD5-positive diffuse large B-cell lymphomas show high specificity for cyclin D2 expression

D cyclins positively regulate the cell cycle and mediate the pathogenesis of some lymphomas. Cyclin D1 overexpression is the hallmark of mantle cell lymphoma, whereas cyclins D2 and D3 are reportedly not as specific to certain lymphomas as cyclin D1. In this study, cyclin D2 was found to be overexpressed in 98% of de novo CD5-positive diffuse large B-cell lymphomas (DLBCLs) (50/51) and in 28% of CD5-negative DLBCLs (14/51). A statistically significant difference was observed between these two groups (p<0.0001). In contrast, no statistical difference was found in the cyclin D3 expression between CD5-positive (18/51) and CD5-negative (24/51) DLBCLs (p=0.23). Based on these findings, cyclin D2 is therefore considered to be closely associated with de novo CD5-positive DLBCLs. This insight may be useful for overcoming the inferior survival of this aggressive lymphoma.

Selective immunophenotyping for diagnosis of B-cell neoplasms: immunohistochemistry and flow cytometry strategies and results

Determining the immunophenotype of hematologic malignancies is now an indispensable part of diagnostic classification, and can help to guide therapy, or to predict clinical outcome. Diagnostic workup should be guided by morphologic findings and evaluate clinically important markers, but ideally should avoid the use of overly broad panels of immunostains that can reveal incidental findings of uncertain significance and give rise to increased costs. Here, we outline our approach to diagnosis of B-cell neoplasms, combining histologic and clinical data with tailored panels of immunophenotyping reagents, in the context of the 2008 World Health Organization classification. We present data from cases seen at our institution from 2004 through 2008 using this approach, to provide a practical reference for findings seen in daily diagnostic practice.

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.

Cyclin D3 coordinates the cell cycle during differentiation to regulate erythrocyte size and number

Genome-wide association studies (GWASs) have identified a genetic variant of moderate effect size at 6p21.1 associated with erythrocyte traits in humans. We show that this variant affects an erythroid-specific enhancer of CCND3. A Ccnd3 knockout mouse phenocopies these erythroid phenotypes, with a dramatic increase in erythrocyte size and a concomitant decrease in erythrocyte number. By examining human and mouse primary erythroid cells, we demonstrate that the CCND3 gene product cyclin D3 regulates the number of cell divisions that erythroid precursors undergo during terminal differentiation, thereby controlling erythrocyte size and number. We illustrate how cell type-specific specialization can occur for general cell cycle components-a finding resulting from the biological follow-up of unbiased human genetic studies.

Histopathology of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a relatively rare lymphoma, accounting for less than 10% only of all lymphomas. Its morphology is quite homogeneous, but it varies strikingly in about 10% of the cases, making the diagnosis of MCL challenging for histopathologists. The definition of the disease was greatly influenced by the discovery of the translocation t(11;14)(q13,q32), which juxtaposes the cyclin D1 and the immunoglobulin heavy chain genes and is present in the vast majority of MCL cases. The introduction of monoclonal antibodies for the detection of cyclin D1 expression into the diagnostic procedure substantially improved the reproducibility and reliability of the pathological diagnosis. However, new challenges for histopathologists have arisen over the last years, among which are the detection of cyclin D1-negative MCL cases and clinically relevant prognostic subgroups.

Cyclin D2 is overexpressed in proliferation centers of chronic lymphocytic leukemia/small lymphocytic lymphoma

The D cyclins are important cell cycle regulatory proteins involved in the pathogenesis of some lymphomas. Cyclin D1 overexpression is a hallmark of mantle cell lymphoma, whereas cyclins D2 and D3 have not been shown to be closely associated with any particular subtype of lymphoma. In the present study, we found that cyclin D2 was specifically overexpressed in the proliferation centers (PC) of all cases of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) examined (19/19). To examine the molecular mechanisms underlying this overexpression, we immunohistochemically examined the expression of nuclear factor (NF)-κB, p15, p16, p18, and p27 in the PC of six patients. Five cases showed upregulation of NF-κB expression, which is known to directly induce cyclin D2 by binding to the promoter region of CCND2. All six PC examined demonstrated downregulation of p27 expression. In contrast, upregulation of p15 expression was detected in five of six PC examined. This discrepancy suggests that unknown cell cycle regulatory mechanisms involving NF-κB-related pathways are also involved, because NF-κB upregulates cyclin D2 not only directly, but also indirectly through c-Myc, which is believed to downregulate both p27 and p15. In conclusion, cyclin D2 is overexpressed in the PC of CLL/SLL and this overexpression is due, in part, to the upregulation of NF-κB-related pathways.

The expression of SOX11, cyclin D1, cyclin D2, and cyclin D3 in B-cell lymphocytic proliferative diseases

SOX11 is mainly correlated with embryo neurogenesis and remodeling of tissues. D cyclins (cyclin D1, cyclin D2, and cyclin D3) work in cell transformation. We assessed the expression of SOX11, cyclin D1, cyclin D2, and cyclin D3 mRNA in 152 patients with B-cell lymphocytic proliferative diseases (B-LPD) using qRT-PCR and we detected SOX11 protein using immunohistochemistry in 15 B-LPD patients, to clarify the clinical significance of the four genes in B-LPD. Data showed the transcriptional levels of SOX11 and cyclin D1 were higher for the mantle cell lymphoma (MCL) samples compared with chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), hairy cell leukemia (HCL), splenic marginal zone lymphoma (SMZL), and healthy collators. The expression levels of cyclin D1 and cyclin D2 were both higher in DLBCL than in SMZL. The expression levels of the four genes were highly related to each other. Three of 4 MCL patients showed nuclear staining for SOX11, while other 11 B-LPD examples were negative. Furthermore, we also found the ZAP70-positive CLL patients had higher SOX11 expression levels than ZAP70-negative CLL patients. It was revealed that MCL patients have higher expression levels of SOX11 and cyclin D1 mRNA, specially expressed nuclear SOX11 protein.

Cyclin D1 positive diffuse large B-cell lymphoma is a post-germinal center-type lymphoma without alterations in the CCND1 gene locus

The aims of this study were to analyze the incidence and morphology of cyclin D1+ DLBCL and cases of Richter transformation (RT), and to elucidate possible molecular mechanisms of cyclin D1 overexpression. Seventy-two cases of de novo DLBCL and 12 cases of RT were included in this study. Cyclin D1 positivity was found in 10/66 (15%) cases of unselected de novo DLBCL and in 2/11 (18%) cases of RT. Seven independently identified cases of cyclin D1+ DLBCL, including one RT, were added to the study. Centroblastic morphology was found in 17/19 (89%) cases of cyclin D1+, most with a post-germinal center phenotype (CD10-, BCL6+, MUM1+). No alterations in the CCND1 gene indicative for a translocation t(11;14) were identified by FISH. Analysis of the MYC locus yielded gene copy alterations in five cases and no disruption of the gene locus in any case, suggesting an alternative mechanism of cyclin D1 deregulation.

Cell cyclins: triggering elements of cancer or not?

Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy.

Immunohistochemical surrogates for genetic alterations of CCDN1, PML, ALK, and NPM1 genes in lymphomas and acute myeloid leukemia

The World Health Organization (WHO) classification of lympho-hemopoietic neoplasms is increasingly based on genetic criteria. Detection of tumor-associated primary genetic lesions is usually performed using the polymerase chain reaction (PCR) and/or fluorescence in-situ hybridization (FISH). This review focuses on alternative techniques for detecting genetic lesions in biopsy samples. Immunohistochemical surrogates for the detection of genetic alterations involving the CCND1, PML, anaplastic lymphoma kinase (ALK) and nucleophosmin (NPM1) genes are presented as examples for this approach. Because of their high specificity, rapidity, low costs and ease of performance, these assays have the potential for being extensively applied in developing countries. In some instances (e.g. detection of ALK protein) immunohistochemistry has fully replaced molecular studies for routine diagnosis in paraffin-embedded specimens. Genome wide based discovery of new tumor-associated genetic lesions that are suitable for antibody targeting promises to further expand the application of immunohistochemistry for the molecular classification of hematological neoplasms.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.