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

PAX5 aberrant expression incorporated in MIPI-SP risk scoring system exhibits additive value in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a subtype of non-Hodgkin lymphoma with highly heterogeneous clinical courses. Paired-box 5 (PAX5), the regulator of B cell differentiation and growth, is abnormally expressed in several types of cancers. Herein, we explored the prognostic value of PAX5 in MCL by comprehensively analyzing the clinical features and laboratory data of 82 MCL cases. PAX5 positivity was associated with shorter overall survival (OS; p = 0.011) and was identified as an independent prognostic factor in MCL patients. The elevated β2-MG (p = 0.027) and advanced Mantle Cell Lymphoma International Prognostic Index (MIPI) score (p = 0.014) were related to positive PAX5 expression. The MIPI-SP risk scoring system was established and exhibited a superior prognostic value for OS depending on an area under the curve (AUC) of 0.770 (95% CI, 0.658-0.881) than MIPI score. Bioinformatic analysis of PAX5-related genes supported the mechanistic roles of PAX5 in MCL. This study provides insight into the potential role of PAX5 in MCL, and the novel risk scoring system MIPI-SP optimizes the risk stratification and facilitates prognosis evaluation in MCL patients. KEY MESSAGES: • Paired-box 5 positivity indicated adverse prognosis in mantle cell lymphoma patients. • Positive PAX5 expression was related to MIPI score and β2-MG in MCL patients. • MIPI-SP risk scoring system has superior prognostic value than MIPI score in MCL.

Clinicopathological and Immunohistochemical Profile of Mantle Cell Lymphoma: An Institutional Experience

Introduction

Mantle cell lymphoma (MCL) is a biologically aggressive B-cell non-Hodgkin lymphoma (NHL) with distinctive morphologic, immunophenotypic, and molecular characteristics. Differentiation from other chronic lymphoproliferative disorders is essential for prognostication.

Aim

This paper aims to study the clinicopathological features of MCL with emphasis on immunohistochemical features and disease correlation.

Method

To do so, clinicopathological characteristics from 21 cases of MCL (14 males, seven females, M:F=2:1) diagnosed in the last five years i.e. 2015 to 2020, were retrospectively reviewed and correlated with immunohistochemistry (IHC) data. Particularly those pertaining to cyclin D1, SRY-box transcription factor 11 (SOX11), cluster of differentiation (CD) 5, CD23, MIB E3 ubiquitin protein ligase 1 (MIB1), tumor protein 53 (TP53), c-myelocytomatosis oncogene product (c-MYC), multiple myeloma oncogene 1 (MUM1), mouse double minute 2 homolog (MDM2), and Epstein-Barr virus latent membrane protein 1 (EBV-LMP1) expression with its aberrations.

Observations

This study shows that MCL constituted 4.2% (21/500) of all NHLs with a mean age of 57.5 years (median 60 years, range 30 to 80 years). The disease was nodal in 19, and extranodal in the remaining two cases. 14 of 21 (67%) had generalized lymphadenopathy and 71% had bone marrow (BM) involvement. The nodal involvement was diffuse in 9/17 (53%), 8/21 (38%) had a blastoid morphology, and an in-situ MCL pattern was not seen in any of the cases selected for the study. Cyclin D1 immunoexpression correlated well with SOX11; CD5-negative in five cases; and CD23-positive in three cases. TP53 and c-MYC expression were noted in 17/19 (89.4%) and 8/17 (47%), respectively. MUM1 registered positive in six cases. None of the cases showed immunopositivity for MDM2 and EBV-LMP1.

Conclusion

In essence, this study indicates that morphological and immunophenotypic subclassification of mantle cell lymphoma with a wider panel of IHC markers is essential for understanding disease biology and better prognostication.

Cell Cycle Dysregulation in Mantle Cell Lymphoma: Genomics and Therapy

Cell cycle dysregulation caused by aberrant cyclin D1 and CDK4 expression is a major determinant for proliferation of cancer cells in mantle cell lymphoma (MCL). Inhibition of CDK4/6 induces G1 arrest of MCL cells in patients, appearing to deepen and prolong the clinical response to partner agents. This article reviews aberrations of cell cycle genes in MCL cells and clinical trials of CDK4/6 inhibitors for MCL. Integrative longitudinal functional genomics is discussed as a strategy to discover genomic drivers for resistance in cancer cells and cancer-immune interactions that potentially contribute to the clinical response to palbociclib combination therapy in MCL.

MDM2/X inhibitors under clinical evaluation: perspectives for the management of hematological malignancies and pediatric cancer

The two murine double minute (MDM) family members MDM2 and MDMX are at the center of an intense clinical assessment as molecular target for the management of cancer. Indeed, the two proteins act as regulators of P53, a well-known key controller of the cell cycle regulation and cell proliferation that, when altered, plays a direct role on cancer development and progression. Several evidence demonstrated that functional aberrations of P53 in tumors are in most cases the consequence of alterations on the MDM2 and MDMX regulatory proteins, in particular in patients with hematological malignancies where TP53 shows a relatively low frequency of mutation while MDM2 and MDMX are frequently found amplified/overexpressed. The pharmacological targeting of these two P53-regulators in order to restore or increase P53 expression and activity represents therefore a strategy for cancer therapy. From the discovery of the Nutlins in 2004, several compounds have been developed and reported with the ability of targeting the P53-MDM2/X axis by inhibiting MDM2 and/or MDMX. From natural compounds up to small molecules and stapled peptides, these MDM2/X pharmacological inhibitors have been extensively studied, revealing different biological features and different rate of efficacy when tested in in vitro and in vivo experimental tumor models. The data/evidence coming from the preclinical experimentation have allowed the identification of the most promising molecules and the setting of clinical studies for their evaluation as monotherapy or in therapeutic combination with conventional chemotherapy or with innovative therapeutic protocols in different tumor settings. Preliminary results have been recently published reporting data about safety, tolerability, potential side effects, and efficacy of such therapeutic approaches. In this light, the aim of this review is to give an updated overview about the state of the art of the clinical evaluation of MDM2/X inhibitor compounds with a special attention to hematological malignancies and to the potential for the management of pediatric cancers.

p53 dysregulation in B-cell malignancies: More than a single gene in the pathway to hell

TP53 deletion or mutation is frequent in B-cell malignancies and is associated with a low response rate. We describe here the p53 landscape in B-cell malignancies, from B-Acute Lymphoblastic Leukemia to Plasma Cell Leukemia, by analyzing incidence of gain or loss of function of actors both upstream and within the p53 pathway, namely MYC, RAS, ARF, MDM2, ATM and TP53. Abnormalities are not equally distributed and their incidence is highly variable among malignancies. Deletion and mutation, usually associated, of ATM or TP53 are frequent in Diffuse Large B-Cell Lymphoma and Mantle Cell Lymphoma. MYC gain, absent in post-GC malignancies, is frequent in B-Prolymphocytic-Leukemia, Multiple Myeloma and Plasma Cell Leukemias. RAS mutations are rare except in MM and PCL. Multiple Factorial Analysis notes that MYC deregulation is closely related to TP53 status. Moreover, MYC gain, TP53 deletion and RAS mutations are inversely correlated with survival. Based on this landscape, we further propose targeted therapeutic approaches for the different B-cell malignancies.

Genome-scale functional analysis of the human genes modulating p53 activity by regulating MDM2 expression in a p53-independent manner

MDM2, a critical negative regulator of p53, is often overexpressed in leukemia, but few p53 mutations are found, suggesting that p53-independent MDM2 expression occurs due to alterations in MDM2 upstream regulators. In this study, a high MDM2 transcription level was observed (41.17%) regardless of p53 expression in patient with acute myeloid leukemia (AML). Therefore, we performed genome-scale functional screening of the human genes modulating MDM2 expression in a p53-independent manner. We searched co-expression profiles of genes showing a positive or negative pattern with MDM2 expression in a DNA microarray database, selected1089 links, and composed a screening library of 368 genes. Using MDM2 P1 and P2 promoter-reporter systems, we screened clones regulating MDM2 transcriptions in a p53-independent manner by overexpression. Nine clones from the screening library showed enhanced MDM2 promoter activity and MDM2 expression in p53-deficient HCT116 cells. Among them, six clones, including NTRK2, GNA15, SFRS2, EIF5A, ELAVL1, and YWHAB mediated MAPK signaling for expressing MDM2. These results indicate that p53-independent upregulation of MDM2 by increasing selected clones may lead to oncogenesis in AML and that MDM2-modulating genes are novel potential targets for AML treatment.

Antitumoral activity of lenalidomide in in vitro and in vivo models of mantle cell lymphoma involves the destabilization of cyclin D1/p27KIP1 complexes

PURPOSE

Clinical responses to the immmunomodulatory drug lenalidomide have been observed in patients with relapsed/refractory mantle cell lymphoma (MCL), although its mechanism of action remains partially unknown. We investigated whether the expression and subcellular localization of cyclin D1, a major cell-cycle regulator overexpressed in MCL, and the cyclin-dependent kinase inhibitor p27(KIP1), could identify MCL cases sensitive to lenalidomide, and whether the compound could modulate cyclin D1/p27(KIP1) complexes in MCL cells.

EXPERIMENTAL DESIGN

MCL primary samples and cell lines were analyzed for subcellular levels of cyclin D1/p27(KIP1) complexes by Western blot, immunohistochemistry, immunoprecipitation, and flow cytometry. Activity of lenalidomide in vitro and its effect on cyclin D1/p27(KIP1) complexes were evaluated by real-time PCR, immunoprecipitation, immunofluorescence, and Western blot. In vivo validation was carried out in a mouse xenograft model of human MCL.

RESULTS

We found cyclin D1 and p27(KIP1) to be coordinately expressed in all the MCL samples tested. Immunoprecipitation analyses and siRNA assays suggested a direct role of cyclin D1 in the regulation of p27(KIP1) levels. The nuclear accumulation of both proteins correlated with MCL cell tumorigenicity in vivo, and sensitivity to lenalidomide activity in vitro and in vivo. Lenalidomide mechanism of action relied on cyclin D1 downregulation and disruption of cyclin D1/p27(KIP1) complexes, followed by cytosolic accumulation of p27(KIP1), cell proliferation arrest, apoptosis, and angiogenesis inhibition.

CONCLUSIONS

These results highlight a mechanism of action of lenalidomide in MCL cases with increased tumorigenicity in vivo, which is mediated by the dissociation of cyclin D1/p27(KIP1) complexes, and subsequent proliferation blockade and apoptosis induction.

MDM2 phenotypic and genotypic profiling, respective to TP53 genetic status, in diffuse large B-cell lymphoma patients treated with rituximab-CHOP immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program

MDM2 is a key negative regulator of the tumor suppressor p53, however, the prognostic significance of MDM2 overexpression in diffuse large B-cell lymphoma (DLBCL) has not been defined convincingly. In a p53 genetically-defined large cohort of de novo DLBCL patients treated with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) chemotherapy, we assessed MDM2 and p53 expression by immunohistochemistry (n = 478), MDM2 gene amplification by fluorescence in situ hybridization (n = 364), and a single nucleotide polymorphism in the MDM2 promoter, SNP309, by SNP genotyping assay (n = 108). Our results show that MDM2 overexpression, unlike p53 overexpression, is not a significant prognostic factor in overall DLBCL. Both MDM2 and p53 overexpression do not predict for an adverse clinical outcome in patients with wild-type p53 but predicts for significantly poorer survival in patients with mutated p53. Variable p53 activities may ultimately determine the survival differences, as suggested by the gene expression profiling analysis. MDM2 amplification was observed in 3 of 364 (0.8%) patients with high MDM2 expression. The presence of SNP309 did not correlate with MDM2 expression and survival. This study indicates that evaluation of MDM2 and p53 expression correlating with TP53 genetic status is essential to assess their prognostic significance and is important for designing therapeutic strategies that target the MDM2-p53 interaction.

HDM-2 inhibition suppresses expression of ribonucleotide reductase subunit M2, and synergistically enhances gemcitabine-induced cytotoxicity in mantle cell lymphoma

Mantle cell lymphoma (MCL) usually responds well to initial therapy but is prone to relapses with chemoresistant disease, indicating the need for novel therapeutic approaches. Inhibition of the p53 E3 ligase human homolog of the murine double minute protein-2 (HDM-2) with MI-63 has been validated as one such strategy in wild-type (wt) p53 models, and our genomic and proteomic analyses demonstrated that MI-63 suppressed the expression of the ribonucleotide reductase (RNR) subunit M2 (RRM2). This effect occurred in association with induction of p21 and cell-cycle arrest at G(1)/S and prompted us to examine combinations with the RNR inhibitor 2',2'-difluoro-2'-deoxycytidine (gemcitabine). The regimen of MI-63-gemcitabine induced enhanced, synergistic antiproliferative, and proapoptotic effects in wtp53 MCL cell lines. Addition of exogenous dNTPs reversed this effect, whereas shRNA-mediated inhibition of RRM2 was sufficient to induce synergy with gemcitabine. Combination therapy of MCL murine xenografts with gemcitabine and MI-219, the in vivo analog of MI-63, resulted in enhanced antitumor activity. Finally, synergy was seen with MI-63-gemcitabine in primary patient samples that were found to express high levels of RRM2 compared with MCL cell lines. These findings provide a framework for translation of the rational combination of an HDM-2 and RNR inhibitor to the clinic for patients with relapsed wtp53 MCL.

Mantle cell lymphoma: biology, pathogenesis, and the molecular basis of treatment in the genomic era

Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma of which at least a subset arises from antigen-experienced B cells. However, what role antigen stimulation plays in its pathogenesis remains ill defined. The genetic hallmark is the chromosomal translocation t(11;14) resulting in aberrant expression of cyclin D1. Secondary genetic events increase the oncogenic potential of cyclin D1 and frequently inactivate DNA damage response pathways. In combination these changes drive cell-cycle progression and give rise to pronounced genetic instability. Several signaling pathways contribute to MCL pathogenesis, including the often constitutively activated PI3K/AKT/mTOR pathway, which promotes tumor proliferation and survival. WNT, Hedgehog, and NF-κB pathways also appear to be important. Although MCL typically responds to frontline chemotherapy, it remains incurable with standard approaches. Proteasome inhibitors (bortezomib), mTOR inhibitors (temsirolimus), and immunomodulatory drugs (lenalidomide) have recently been added to the treatment options in MCL. The molecular basis for the antitumor activity of these agents is an area of intense study that hopefully will lead to further improvements in the near future. Given its unique biology, relative rarity, and the difficulty in achieving long-lasting remissions with conventional approaches, patients with MCL should be encouraged to participate in clinical trials.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.

Mantle cell lymphoma: state-of-the-art management and future perspective

Mantle cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphomas (NHL) characterized in almost all cases by the chromosomal translocation t(11;14)(q13;q32) and nuclear cyclin D1 overexpression. Most patients present with advanced stage disease, often with extranodal dissemination, and typically pursue an aggressive clinical course. Recent improvement has been achieved by the successful introduction of monoclonal antibodies and dose-intensified approaches including autologous stem cell transplantation strategies. However, with the exception of allogeneic hematopoietic stem cell transplantation, current treatment approaches are not curative and the corresponding survival curve is characterized by a relatively steep and continuous decline, with a median survival of about 4 years and <15% long-term survivors. Despite its rarity, MCL is of particular clinical and scientific interest by providing a paradigm for neoplasms with dysregulated control of cell cycle machinery and impaired apoptotic pathways. Recently gained insights into underlying pathobiology unravel numerous promising molecular targeting strategies, however their introduction into clinical practice and current treatment algorithms remains a challenge. This article will provide relevant information for decision making in clinical practice and give a perspective on upcoming management strategies.

Polymorphisms in p53 and the p53 pathway: roles in cancer susceptibility and response to treatment

The p53 tumour suppressor protein lies at the crossroads of multiple cellular response pathways that control the fate of the cell in response to endogenous or exogenous stresses and inactivation of the p53 tumour suppressor signalling pathway is seen in most human cancers. Such aberrant p53 activity may be caused by mutations in the TP53 gene sequence producing truncated or inactive mutant proteins, or by aberrant production of other proteins that regulate p53 activity, such as gene amplification and overexpression of MDM2 or viral proteins that inhibit or degrade p53. Recent studies have also suggested that inherited genetic polymorphisms in the p53 pathway influence tumour formation, progression and/or response to therapy. In some cases, these variants are clearly associated with clinico-pathological variables or prognosis of cancer, whereas in other cases the evidence is less conclusive. Here, we review the evidence that common polymorphisms in various aspects of p53 biology have important consequences for overall tumour susceptibility, clinico-pathology and prognosis. We also suggest reasons for some of the reported discrepancies in the effects of common polymorphisms on tumourigenesis, which relate to the complexity of effects on tumour formation in combination with other oncogenic changes and other polymorphisms. It is likely that future studies of combinations of polymorphisms in the p53 pathway will be useful for predicting tumour susceptibility in the human population and may serve as predictive biomarkers of tumour response to standard therapies.

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.

Molecular biology and genetics of lymphomas

This article summarizes molecular and genetic features of B-cell non-Hodgkin lymphoma and focuses on diffuse large B-cell lymphoma, Burkitt lymphoma, follicular lymphoma, and mantle cell lymphoma. In each of these entities, hallmark genetic aberrations, cytogenetic characteristics, and alterations of single genes that might be involved in the pathogenesis and molecular evolution of the tumor are described. Recent results from gene-expression profiling studies are incorporated that are relevant for the classification of lymphoma entities, the prediction of their clinical behavior, and the identification of deregulated signal-transduction pathways that might represent potential targets in future therapeutic approaches.

Five-gene model to predict survival in mantle-cell lymphoma using frozen or formalin-fixed, paraffin-embedded tissue

PURPOSE

Despite the common underlying translocation t(11;14) involving cyclin D1 that is present in nearly all cases of mantle-cell lymphoma (MCL), the clinical course of the disease is highly variable. The aim of the present study was to develop a quantitative gene expression-based model to predict survival in newly diagnosed patients with MCL that involves a minimum number of genes and is applicable to fresh-frozen and formalin-fixed, paraffin-embedded (FFPE) tumor samples.

PATIENTS AND METHODS

The expression of 33 genes with potential prognostic and pathogenetic impact in MCL was analyzed using quantitative reverse-transcription polymerase chain reactions (qRT-PCR) in a low-density array format in frozen tumor samples from 73 patients with MCL. Multivariate Cox methods and stepwise algorithms were applied to build gene expression-based survival predictors. An optimized five-gene model was subsequently applied to FFPE tumor samples from 13 patients with MCL from the initial series and to 42 independent MCL samples.

RESULTS

The optimized survival predictor was composed of the five genes RAN, MYC, TNFRSF10B, POLE2, and SLC29A2 and was validated for application in FFPE tissue samples. It allowed the survival prediction of patients with MCL with widely disparate clinical outcome and was superior to the immunohistochemical marker Ki-67, an established prognostic factor in MCL.

CONCLUSION

We here present a validated qRT-PCR-based test for survival prediction in patients with MCL that is applicable to fresh frozen as well as to FFPE tissue specimens. This test may prove useful to guide individualized treatment approaches for patients with MCL.

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.

Genetic and molecular pathogenesis of mantle cell lymphoma: perspectives for new targeted therapeutics

Mantle cell lymphoma (MCL) is a well-defined lymphoid malignancy characterized by a rapid clinical evolution and poor response to current therapeutic protocols. The genetic and molecular mechanisms involved in its pathogenesis combine the dysregulation of cell proliferation and survival pathways with a high level of chromosome instability that seems related to the disruption of the DNA damage response pathway. Understanding these mechanisms and how they affect tumour behaviour is providing the rationale for the identification of reliable predictors of clinical evolution and the design of innovative therapeutic strategies that could open new avenues for the treatment of patients with MCL.