Altered Apoptosis Pathways in Mantle Cell Lymphoma

Combining T-cell-based immunotherapy with venetoclax elicits synergistic cytotoxicity to B-cell lines in vitro

Alterations of B-cell lymphoma 2 (BCL-2) family proteins contribute to the survival of B-cell malignancies. Recently, venetoclax, a BCL-2 inhibitor, was approved for B-cell chronic lymphocytic leukemia therapy and is being investigated in clinical trials for a variety of hematologic cell malignancies. Furthermore, combination therapy with other molecularly targeted drugs was reported to be more effective than monotherapy. However, combining venetoclax with immunotherapy based on T-cells has not been tested. Because both venetoclax and granzyme B activate the mitochondrial apoptosis pathway by targeting different BCL-2 family molecules, it is possible that combinations of venetoclax with immunotherapy will be effective treatments. We examined the effect of combining venetoclax with immunotherapy using an in vitro model system involving cytomegalovirus (CMV) pp65 antigen-specific cytotoxic T-cells (CMV-CTLs) as the effector cells and CMVpp65 antigen-expressing B-cell lines as the target cells. Cytotoxicity of CMV-CTLs to the target B-cell lines was enhanced by venetoclax with combination index values of 0.47-0.83. This suggests that venetoclax synergizes with T-cell-based immunotherapy to affect B-cell malignancies. Interestingly, venetoclax synergized not only with antigen-specific cytotoxicity but also with nonspecific cytotoxicity. Importantly, CMV-CTLs could be expanded in the presence of venetoclax at the maximum concentration (5 μM) that induced apoptosis in resting CMV-CTLs. B-cell lymphoma-extra large (BCL-xL) expression in CMV-CTLs increased transiently after activation by CMVpp65-transfected B-cell lines, indicating that the expression of BCL-xL was important for the effectiveness of combination treatment with venetoclax. These findings suggest that T-cell-based immunotherapy combined with venetoclax is effective against B-cell malignancies.

Immunophenotypic Characterization of Canine Splenic Follicular-Derived B-Cell Lymphoma

Marginal zone lymphoma (MZL) and mantle cell lymphoma (MCL) belong to a subgroup of indolent B-cell lymphomas most commonly reported in the canine spleen. The goal of this study was to characterize the immunophenotype of splenic MZL and MCL in comparison to their human counterparts. Ten MCLs and 28 MZLs were selected based on morphology. A tissue microarray was generated, and expression of CD3, CD5, CD10, CD45, CD20, CD79a, Pax-5, Bcl-2, Bcl-6, cyclin D1, cyclin D3, MCL-1, MUM-1, and Sox-11 was evaluated. Neoplastic cells in all MCLs and MZLs were positive for CD5, CD20, CD45, CD79a, and BCL2 and negative for CD3, CD10, Bcl-6, cyclin D1, and cyclin D3. Positive labeling for Pax-5 was detected in 8 of 10 MCLs and 26 of 28 MZLs. Positive labeling for MUM-1 was detected in 3 of 10 MCLs, and 27 of 28 MZLs were positive for MUM-1. No MCLs but 8 of 24 MZLs were positive for MCL-1. Canine splenic MZL and MCL have a similar immunophenotype as their human counterparts. However, human splenic MCL overexpresses cyclin D1 due to a translocation. A similar genetic alteration has not been reported in dogs. In addition, in contrast to human MZL, canine splenic MZL generally expresses CD5. Following identification of B vs T cells with CD20 and CD3, a panel composed of BCL-2, Bcl-6, MUM-1, and MCL-1 combined with the histomorphological pattern can be used to accurately diagnose MZL and MCL in dogs. Expression of Bcl-2 and lack of MCL-1 expression in MCL may suggest a therapeutic benefit of BCL-2 inhibitors in canine MCL.

Targeting the Bcl-2 Family in B Cell Lymphoma

Although lymphoma is a very heterogeneous group of biologically complex malignancies, tumor cells across all B cell lymphoma subtypes share a set of underlying traits that promote the development and sustain malignant B cells. One of these traits, the ability to evade apoptosis, is essential for lymphoma development. Alterations in the Bcl-2 family of proteins, the key regulators of apoptosis, is a hallmark of B cell lymphoma. Significant efforts have been made over the last 30 years to advance knowledge of the biology, molecular mechanisms, and therapeutic potential of targeting Bcl-2 family members. In this review, we will highlight the complexities of the Bcl-2 family, including our recent discovery of overexpression of the anti-apoptotic Bcl-2 family member Bcl-w in lymphomas, and describe recent advances in the field that include the development of inhibitors of anti-apoptotic Bcl-2 family members for the treatment of B cell lymphomas and their performance in clinical trials.

Promising efficacy of novel BTK inhibitor AC0010 in mantle cell lymphoma

PURPOSE

We researched into the effect and mechanism of AC0010, a novel BTK inhibitor, in MCL, and compared its efficacy and safety with Ibrutinib to develop a preclinical study for the future therapy of MCL.

METHODS

MTS assay was used to detect the growth inhibition caused by AC0010 and Ibrutinib, respectively, in MCL cell lines (Jeko-1 and JVM-2), primary MCL cells, and normal peripheral lymphocytes. Apoptosis of Jeko-1 and JVM-2 after exposure into AC0010 and Ibrutinib was conducted by flow cytometry; the expression of apoptosis-related proteins was checked by Western blot. q-PCR and Western blot were applied to examine the expression of BTK and p-BTK at mRNA and protein level as well as the BTK-ralated signaling pathways. MCL xenograft was developed to testify the efficacy and safety of AC0010 in vivo.

RESULTS

In contrast with Ibrutinib, AC0010 proved to be more toxic to MCL cells in vitro (p < 0.01) with no augment in cytotoxicity to normal peripheral lymphocytes, and it can induce obvious apoptosis in MCL cell lines (p < 0.01) through caspase family and Bcl-2 family. AC0010 at 300 mg/kg can prolong the survival rate in MCL xenograft (p < 0.01). The phosphorylation of BTK is inhibited by AC0010 following simultaneously inhibition of BCR-BTK and PI3K/AKT signaling pathway in MCL cells.

CONCLUSION

AC0010 is a novel BTK inhibitor of great efficacy and safety in MCL.

Targeting netrin-1/DCC interaction in diffuse large B-cell and mantle cell lymphomas

DCC (Deleted in Colorectal Carcinoma) has been demonstrated to constrain tumor progression by inducing apoptosis unless engaged by its ligand netrin‐1. This has been shown in breast and colorectal cancers; however, this tumor suppressive function in other cancers is not established. Using a transgenic mouse model, we report here that inhibition of DCC‐induced apoptosis is associated with lymphomagenesis. In human diffuse large B‐cell lymphoma (DLBCL), an imbalance of the netrin‐1/DCC ratio suggests a loss of DCC‐induced apoptosis, either via a decrease in DCC expression in germinal center subtype or by up‐regulation of netrin‐1 in activated B‐cell (ABC) one. Such imbalance is also observed in mantle cell lymphoma (MCL). Using a netrin‐1 interfering antibody, we demonstrate both in vitro and in vivo that netrin‐1 acts as a survival factor for ABC‐DLBCL and MCL tumor cells. Together, these data suggest that interference with the netrin‐1/DCC interaction could represent a promising therapeutic strategy in netrin‐1‐positive DLBCL and MCL.

Recent advances in the management of mantle cell lymphoma

PURPOSE OF REVIEW

This review will discuss the most recent literature regarding frontline therapy, treatment of patients not eligible for intensive chemotherapy, and novel agents for relapsed/refractory patients with mantle cell lymphoma (MCL).

RECENT FINDINGS

Longer follow-up of previously studied intensive regimens still demonstrates encouraging results, but late relapses are still evident. Consolidation and maintenance strategies continue to be attractive options to be explored in this disease that is characterized by frequent relapses and short remissions. The combination of bendamustine-rituximab was demonstrated to be noninferior and less toxic to R-CHOP and should be considered the new standard of care for elderly patients. Multiple novel agents directed towards different molecular targets like BTK, mTOR, PI3K, HDAC, and BCL-2, involved in the pathogenesis of MCL have shown promising results.

SUMMARY

Management of MCL still represents a challenge due to heterogeneity of the disease. As we approach the molecular era of oncology, future strategies should focus on combination of newer agents with known effective regimens to improve outcome.

Discrepant NOXA (PMAIP1) transcript and NOXA protein levels: a potential Achilles' heel in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive lymphoid neoplasm with transient response to conventional chemotherapy. We here investigated the role of the Bcl-2 homology domain 3-only protein NOXA for life–death decision in MCL. Surprisingly, NOXA (PMAIP1) mRNA and NOXA protein levels were extremely discrepant in MCL cells: NOXA mRNA was found to be highly expressed whereas NOXA protein levels were low. Chronic active B-cell receptor signaling and to a minor degree cyclin D1 overexpression contributed to high NOXA mRNA expression levels in MCL cells. The phoshatidyl-inositol-3 kinase/AKT/mammalian target of rapamycin pathway was identified as the major downstream signaling pathway involved in the maintenance of NOXA gene expression. Interestingly, MCL cells adapt to this constitutive pro-apoptotic signal by extensive ubiquitination and rapid proteasomal degradation of NOXA protein (T_½∼15–30 min). In addition to the proteasome inhibitor Bortezomib, we identified the neddylation inhibitor MLN4924 and the fatty acid synthase inhibitor Orlistat as potent inducers of NOXA protein expression leading to apoptosis in MCL. All inhibitors targeted NOXA protein turnover. In contrast to Bortezomib, MLN4924 and Orlistat interfered with the ubiquitination process of NOXA protein thereby offering new strategies to kill Bortezomib-resistant MCL cells. Our data, therefore, highlight a critical role of NOXA in the balance between life and death in MCL. The discrepancy between NOXA transcript and protein levels is essential for sensitivity of MCL to ubiquitin-proteasome system inhibitors and could therefore provide a druggable Achilles' heel of MCL cells.

Gene methylation and silencing of SOCS3 in mantle cell lymphoma

The significance of loss of SOCS3, a negative regulator of signalling pathways including those of STAT3 and NF-κB, was examined in mantle cell lymphoma (MCL). The protein expression and gene methylation status of SOCS3 were detected using immunohistochemistry/Western blots and methylation-specific polymerase chain reaction, respectively. To evaluate its functional importance, SOCS3 was restored in two SOCS3-negative MCL cell lines using a lentiviral vector. Loss of SOCS3 protein expression was found in 3/4 MCL cell lines and 18/33 (54.5%) tumours. SOCS3 was found consistently methylated in cell lines (3/4) and tumours (7/7) negative for SOCS3, and was unmethylated in all SOCS3-positive cell line (1/1) and tumours (5/5) examined. Treatment of all three SOCS3-negative cell lines with 2'-deoxy-5-azacytidine restored SOCS3 expression. SOCS3 is biologically important in MCL, as lentiviral transfer of SOCS3 in SOCS3-negative cell lines increased their apoptotic activity, downregulated nuclear factor (NF)-κB-p65, cyclin D1 (CCND1), BCL2 and BCL-XL (BCL2L1), and substantially dampened interleukin 10-induced STAT3 activation. In 19 patients aged ≤ 69 years at time of diagnosis, we found that those that carried SOCS3-negative tumours showed a trend toward a worse outcome (P = 0.1, log-rank).

Mesenchymal stromal cells protect mantle cell lymphoma cells from spontaneous and drug-induced apoptosis through secretion of B-cell activating factor and activation of the canonical and non-canonical nuclear factor κB pathways

BACKGROUND

There is increasing evidence that stromal cell interactions are required for the survival and drug resistance of several types of B-cell malignancies. There is relatively little information regarding the role of the bone marrow/lymphoid microenvironment in the pathogenesis of mantle cell lymphoma. In this study we investigated the interaction of primary mantle cell lymphoma cells with stromal cells in an ex vivo co-culture system.

DESIGN AND METHODS

The murine stromal cell line MS-5 and human bone marrow mesenchymal stromal cells were each co-cultured with primary mantle cell lymphoma cells for up to 7 months. Mantle cell lymphoma cultures alone or combined with human stromal cells were analyzed for cell number, cell migration, nuclear factor-κB activation and drug resistance.

RESULTS

Co-culture of mantle cell lymphoma cells and human stromal cells results in the survival and proliferation of primary mantle cell lymphoma cells for at least 7 months compared to mantle cell lymphoma cells cultured alone. Mantle cell lymphoma-human stromal cell interactions resulted in activation of the B-cell activating factor/nuclear factor-κB signaling axis resulting in reduced apoptosis, increased mantle cell lymphoma migration and increased drug resistance.

CONCLUSIONS

Direct mantle cell lymphoma-human stromal cell interactions support long-term expansion and increase the drug-resistance of primary mantle cell lymphoma cells. This is due in part to activation of the canonical and non-canonical nuclear factor κB pathways. We also demonstrated the ability of B-cell activating factor to augment CXCL12- and CXCL13-induced cell migration. Collectively, these findings demonstrate that human stromal cell-mantle cell lymphoma interactions play a pivotal role in the pathogenesis of mantle cell lymphoma and that analysis of mantle cell lymphoma-human stromal cell interactions may help in the identification of novel targets for therapeutic use.

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.

Retinoic acid/alpha-interferon combination inhibits growth and promotes apoptosis in mantle cell lymphoma through Akt-dependent modulation of critical targets

Mantle cell lymphoma (MCL) is characterized by a profound deregulation of the mechanisms controlling cell-cycle progression and survival. We herein show that the combination of 9-cis-retinoic acid (RA) and IFN-α induces marked antiproliferative and proapoptotic effects in MCL cells through the modulation of critical targets. Particularly, IFN-α enhances RA-mediated G(0)-G(1) cell accumulation by downregulating cyclin D1 and increasing p27(Kip1) and p21(WAF1/Cip1) protein levels. Furthermore, RA/IFN-α combination also induces apoptosis by triggering both caspases-8 and -9 resulting in Bax and Bak activation. In particular, RA/IFN-α treatment downregulates the antiapoptotic Bcl-xL and Bfl-1 proteins and upregulates the proapoptotic BH3-only Noxa protein. Sequestration of Mcl-1 and Bfl-1 by upregulated Noxa results in the activation of Bid, and the consequent induction of apoptosis is inhibited by Noxa silencing. Noxa upregulation is associated with nuclear translocation of the FOXO3a transcription factor as consequence of RA/IFN-α-induced Akt inhibition. Pharmacologic suppression of Akt, but not of TORC1, increases Noxa protein levels and downregulates Bfl-1 protein supporting the conclusion that the inhibition of the Akt pathway, the resulting FOXO3a activation and Noxa upregulation are critical molecular mechanisms underlying RA/IFN-α-dependent MCL cell apoptosis. These results support the potential therapeutic value of RA/IFN-α combination in MCL management.

The tumour suppressor FOXO3 is a key regulator of mantle cell lymphoma proliferation and survival

The FOXO3 (Forkhead/winged helix box class O 3) transcription factor is a crucial regulator of haematopoietic cell fate that controls proliferation and apoptosis, among other processes. Despite the central role of FOXO3 as a tumour suppressor and phosphatidylinositol 3-kinase (PI3K)/AKT effector, little is known about its involvement in mantle cell lymphoma (MCL) biology. This study investigated the expression and activity of FOXO3 in MCL cell lines and in primary cultures. We analysed the expression of key FOXO regulators and targets, and studied the effect of modulators of FOXO function on cell viability and apoptosis. FOXO3 was constitutively inactivated in MCL cell lines, and showed cytoplasmic localization in patient-derived cells. PI3K and AKT, but not mammalian target of rapamycin (mTOR), inhibitors induced FOXO3 nuclear translocation and activation in correlation with their impact on MCL proliferation and survival. Moreover, FOXO3-defective cells were resistant to PI3K/AKT inhibitors. Reactivation of FOXO function with a nuclear export inhibitor had a profound effect on cell viability, consistent with FOXO3 nuclear accumulation. Interestingly, inhibition of FOXO3 nuclear export enhanced the effect of doxorubicin. Taken together, our results confirm that FOXO3 is a relevant regulator of proliferation and apoptosis in MCL, and suggest that reactivation of FOXO3 function might be a useful therapeutic strategy in MCL patients.

Curcumin nanodisk-induced apoptosis in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a pre-germinal center neoplasm characterized by cyclin D1 overexpression resulting from t(11;14)(q13;q32). Since MCL is incurable with standard lymphoma therapies, new treatment approaches are needed that target specific biologic pathways. In the present study, we investigated a novel drug delivery nanovehicle enriched with the bioactive polyphenol, curcumin (curcumin nanodisks; curcumin-ND). Cells treated with curcumin-ND showed a dose-dependent increase in apoptosis. This was accompanied by enhanced generation of reactive oxygen species (ROS). The antioxidant, N-acetylcysteine, inhibited curcumin-ND induced apoptosis, suggesting that ROS generation plays a role in curcumin action on MCL cells. Curcumin-ND decreased cyclin D1, pAkt, pIκBα, and Bcl(2) protein. In addition, enhanced FoxO3a and p27 expression as well as caspase-9, -3, and poly(ADP-ribose) polymerase (PARP) cleavage were observed. Curcumin-ND treatment led to enhanced G(1) arrest in two cultured cell models of MCL.

Mantle cell lymphoma in relapse: the role of emerging new drugs

PURPOSE OF REVIEW

Despite current advances in the therapy for newly diagnosed mantle cell lymphoma (MCL), relapsed MCL continues to have a poor prognosis. Advances in our understanding of the molecular pathogenesis of MCL are yielding many promising novel therapies.

RECENT FINDINGS

This article reviews the unique biology of MCL and describes how our understanding of its cell cycle dysregulation, and impaired apoptotic pathways is yielding many potential therapeutic targets including cyclin D1 and the cell cycle regulatory proteins, inhibitors of mammalian target of rapamycin, the proteasome, and proapoptotic family members. Recent preclinical and clinical data with cdk inhibitors, histone deacetylase inhibitors, the proteasome inhibitor bortezomib, mammalian target of rapamycin inhibitors, and other experimental strategies such as immunotherapy and microRNA are discussed.

SUMMARY

Understanding these targeted therapies in the context of the biology of MCL, has the potential to develop novel therapeutic platforms for the treatment of relapsed MCL, and will hopefully change the outcome for patients with this challenging clinical condition.

Germline variation in apoptosis pathway genes and risk of non-Hodgkin's lymphoma

BACKGROUND

The t(14;18)(q32;q21) translocation is the most commonly observed chromosomal translocation in non-Hodgkin's lymphoma (NHL), resulting in constitutive Bcl-2 expression and apoptosis inhibition. In addition, germline variation in both BCL2L11 (BIM) and CASP9, known regulators of apoptosis, has recently been linked to NHL risk. We conducted a comprehensive evaluation of 36 apoptosis pathway genes with risk of NHL.

METHODS

We genotyped 226 single-nucleotide polymorphisms (SNP) from 36 candidate genes in a clinic-based study of 441 newly diagnosed NHL cases and 475 frequency-matched controls. We used principal components analysis to assess gene-level associations, and logistic regression to assess SNP-level associations. MACH was used for imputation of SNPs in BCL2L11 and CASP9.

RESULTS

In gene-level analyses, BCL2L11 (P = 0.0019), BCLAF1 (P = 0.0097), BAG5 (P = 0.026), and CASP9 (P = 0.0022) were associated with NHL risk after accounting for multiple testing (tail strength, 0.38; 95% confidence interval, 0.05-0.70). Two of the five BCL2L11 tagSNPs (rs6746608 and rs12613243), both genotyped BCLAF1 tagSNPs (rs797558 and rs703193), the single genotyped BAG5 tagSNP (rs7693), and three of the seven genotyped CASP9 tagSNPs (rs6685648, rs2020902, and rs2042370) were significant at P < 0.05. We successfully imputed BCL2L11 and CASP9 SNPs previously linked to NHL, and replicated all four BCL2L11 and two of three CASP9 SNPs.

CONCLUSION

We replicated the association of BCL2L11 and CASP9 with NHL risk at the gene and SNP level, and identified novel associations with BCLAF1 and BAG5.

IMPACT

Closer evaluation of germline variation of genes in the apoptosis pathway with risk of NHL and its subtypes is warranted.

Romidepsin and belinostat synergize the antineoplastic effect of bortezomib in mantle cell lymphoma

PURPOSE

Romidepsin and belinostat are inhibitors of histone deacetylases (HDACI). HDACIs are known to induce cell death in malignant cells through multiple mechanisms, including upregulation of death receptors and induction of cell cycle arrest. They are also known to be prodifferentiating. Mantle cell lymphoma (MCL) is an aggressive subtype of non-Hodgkin lymphoma characterized by the t(11;14)(q13;q32) translocation leading to the overexpression of cyclin D1.

EXPERIMENTAL DESIGN

Assays for cytotoxicty including mathematical analysis for synergism, flow-cytometry, immunoblottings, and a xenograft severe combined immunodeficient beige mouse model were used to explore the in vitro and in vivo activity of romidepsin and/or belinostat alone or in combination with the proteasome inhibitor bortezomib in MCL.

RESULTS

In vitro, romidepsin and belinostat exhibited concentration-dependent cytotoxicity against a panel of MCL cell lines. Both HDACI showed strong synergism when combined with the proteasome inhibitor bortezomib in MCL. An HDACI plus bortezomib also induced potent mitochondrial membrane depolarization and apoptosis, whereas no significant apoptosis was observed in peripheral blood mononuclear cells from healthy donors with the combination. These events were associated with a decrease in cyclin D1 and Bcl-X(L), and an increase in accumulation of acetylated histone H3, acetylated alpha-tubulin, and Noxa in cell lines. In a severe combined immunodeficient beige mouse model of MCL, the addition of belinostat to bortezomib enhanced efficacy compared with either drug alone.

CONCLUSIONS

Collectively, these data strongly suggest that HDACI such as romidepsin or belinostat in combination with a proteasome inhibitor could represent a novel and rationale platform for the treatment of MCL.

Developing curcumin into a viable therapeutic for lymphoma

BACKGROUND

Emerging evidence suggests that natural plant ingredients have played an important role in the healthcare of many countries. Several of these natural plant products possess therapeutic potential for various diseases including cancer. Curcumin is the pigment of turmeric, a well-known chemopreventive agent that has been shown to suppress the proliferation of a wide variety of tumor cells, including lymphoma. Curcumin has been shown to have cancer chemopreventive potential against a variety of tumors via targeting key survival pathways that are aberrantly activated in cancer cells.

METHODS

This review discusses therapeutic potential of curcumin in malignancies of lymphoma as well as therapeutic implications of the recent advances in the field.

RESULTS/CONCLUSION

Dietary-compound curcumin hardwires to multiple cellular processes. Suppression of cell proliferation, induction of apoptosis, and inhibition of metastasis are considered to be the major mechanisms underlying its anticancer properties.

CDK4 IVS4-nt40 AA genotype and obesity-associated tumors/cancer in Italians - a case-control study

Background

Cell cycle checkpoint regulation is crucial for prevention of tumor in mammalian cells. Cyclin-dependant kinase 4 (CDK4) is important in cell cycle regulation, as it controls the G1-S phase of the cell cycle. CDK4 has potential mitogenic properties through phosphorylation of target proteins. We aimed at identifying a role of CDK4 IVS4-nt40 G→A gene variant in benign and/or malignant tumors and in obesity-associated benign and/or malignant tumors in an Italian adult subject dataset.

Methods

We recruited 263 unrelated Italian subjects: 106 subjects had at least one benign tumor and 46 subjects had at least one malignant tumor, while 116 subjects had at least two tumors and/or cancers. We collected BMI data for 90% of them: 186 subjects had a BMI≥30 Kg/m² and 52 subjects had a BMI ≥ 30 Kg/m². We performed statistical power calculations in our datasets. DNA samples were directly sequenced with specific primers for the CDK4 IVS4-nt40 G→A variant. Genotype association tests with disease were performed.

Results

In our study, no significant association of the CDK4 IVS4-nt40 AA genotype with cancer and/or tumors/cancer are/is detected. However, the CDK4 IVS4-nt40 AA genotype is significantly associated with cancer and tumors/cancer in obese patients.

Conclusion

This finding is interesting since obesity is a risk factor for tumors and cancer. This study should prompt further work aiming at establishing the role of CDK4 in contributing to tumor/cancer genetic risk predisposition, as well as its role as a potentially effective therapeutic target gene for obesity-associated tumor/cancer management.

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.

Development of a murine model for blastoid variant mantle-cell lymphoma

Blastoid-variant mantle-cell lymphoma (MCL-BV), unlike most B-cell non-Hodgkin lymphomas (NHL-Bs), is refractory to conventional chemotherapy and associated with a very poor prognosis. Development of new therapies has been hampered by the lack of valid animal models. We have developed a novel murine model of MCL-BV by crossing interleukin 14alpha (IL-14alpha) transgenic mice with c-Myc transgenic mice (double transgenic [DTG]). IL-14alpha is a B-cell growth factor that is expressed in a number of high-grade lymphomas, including MCL-BV. Ninety-five percent of IL-14alpha transgenic mice develop CD5(+) large B-cell lymphomas by 18 months of age. Sixty percent of c-Myc transgenic mice develop pre-B-cell lymphomas by 12 months of age. Close to 100% of DTG mice develop an aggressive, rapidly fatal lymphoma at 3 to 4 months of age that is CD5(+), CD19(+), CD21(-), CD23(-), sIgM(+). The tumor is found in the blood, bone marrow, liver, spleen, lymph nodes, gastrointestinal tract, and lungs and rarely in the brain, similar to the involvement seen in human MCL-BV. Immunoglobulin gene rearrangements document the monoclonality of the tumor. Cyclin D1 is highly expressed in these tumors, as it is in MCL-BV. DTG represents a novel model for MCL-BV that should reveal important insights into the pathogenesis of the lymphoma and contribute to the development of new forms of therapy.

From Gene Expression Analysis to Tissue Microarrays

Mantle cell lymphoma (MCL) is an aggressive lymphoid malignancy for which better treatment strategies are needed. To identify potential diagnostic and therapeutic targets, a signature consisting of MCL-associated genes was selected based on a comprehensive gene expression analysis of malignant and normal B cells. The corresponding protein epitope signature tags were identified and used to raise monospecific, polyclonal antibodies, which were subsequently analyzed on paraffin-embedded sections of malignant and normal tissue. In this study, we demonstrate that the initial selection strategy of MCL-associated genes successfully allows identification of protein antigens either uniquely expressed or overexpressed in MCL compared with normal lymphoid tissues. We propose that genome-based, affinity proteomics, using protein epitope signature tag-induced antibodies, is an efficient way to rapidly identify a number of disease-associated protein candidates of both previously known and unknown identities.

Trisomy 12-associated, t(11;14)-negative mature B-cell leukemia with gene expression profile resembling mantle cell lymphoma

Trisomy 12 can be seen in many different lymphoid neoplasms. However, many or most mature B-cell leukemias associated with isolated trisomy 12 are reported in the literature as chronic lymphocytic leukemia (CLL) or 'atypical CLL'. This study reports a case of a mature B-cell leukemia, morphologically and immunophenotypically similar to cases previously published as atypical CLL, in which cytogenetic evaluation revealed an isolated clonal trisomy 12 but no evidence of the mantle cell lymphoma-associated t(11;14)(q13;q32). Further analysis confirmed absence of cyclin-D1 expression. Subsequent lymph node biopsy revealed evidence of large cell transformation of the underlying chronic lymphoproliferative disorder. Gene expression profiling of the initial peripheral blood sample using a cDNA micro-array of approximately 10,000 expressed genes revealed a close resemblance between the reported case and 2 cases of known mantle cell lymphoma. When further compared to 7 known 'typical' CLL cases, the reported case was classified as mantle cell lymphoma by hierarchical cluster analysis. The case reported here raises interesting questions regarding the nature of cases reported previously as trisomy 12-associated CLL and reinforces the fact that other leukemic lymphoproliferative disorders should be included in the differential diagnosis of such cases. Further study is indicated to elucidate the nature and diversity of disorders previously reported as trisomy 12-associated chronic lymphocytic leukemia.

Expression of the cyclin-dependent kinase inhibitor p27 and its deregulation in mouse B cell lymphomas

CDKN1B (p27) regulates cell-cycle progression at the G1-S transition by suppressing the cyclin E/CDK2 kinase complex. In normal lymphocytes and most human B cell non-Hodgkin lymphomas (NHL), there is an inverse correlation between proliferative activity and expression of p27; however, a subset of NHL with high mitotic indices expresses p27, which is inactive due to sequestration in nuclear protein complexes or due to cytoplasmic retention. Our studies of mouse B cell NHL also identified cases with high proliferative activity and high levels of p27 at a surprisingly high frequency. Here, p27 was complexed with D-type cyclins 1 and 3 and with the COPS9 protein, JAB1. In addition, we found cytoplasmic sequestration following phosphorylation by activated AKT.

The -omics era and its impact

OBJECTIVE

To review the advances in clinically useful molecular biologic techniques and to identify their applications, as presented at the 12th Annual William Beaumont Hospital DNA Symposium.

DATA SOURCES

The 7 manuscripts submitted were reviewed and their major findings were compared with literature on the same or related topics.

STUDY SELECTION

Manuscripts address the use of molecular techniques in the detection of severe acute respiratory syndrome (SARS) and bacterial ribosome mutations, which may lead to ribosome-targeted drug resistance; pharmacogenomics as a clinical laboratory service and example of warfarin dosing using CYP2C9 mutation analysis; definition of the potential of cytosine arabinoside incorporation into DNA to disrupt transcription using an in vitro model of oligonucleotides; use of laser capture microdissection to isolate solid tumor cells free of nontumor cells; and molecular methods used to classify lymphomas.

DATA SYNTHESIS

Two current issues related to the use of molecular tests in the clinical laboratories are (1) decentralization of molecular-based testing to a variety of nonmolecular laboratories and (2) need for wider acceptance of molecular-based testing through its incorporation in clinical practice guidelines. Molecular methods have had a major impact on infectious disease through the rapid identification of new infectious agents, SARS, and the characterization of drug resistance. Pharmacogenomics identifies the genetic basis for heritable and interindividual variation in response to drugs. The incorporation of the nucleoside analog, cytosine arabinoside, into DNA leads to local perturbation of DNA structure and reduces the ability of transcription factors to bind to their specific DNA binding elements as measured by electrophoretic mobility shift assays. Laser capture microdissection of tumor cells can provide an adequate number of cells for whole genome amplification. Gene expression microassay profiles of various lymphomas have modified classification systems and predict prognosis and response to therapy.

CONCLUSIONS

The current -omics era will continue to emphasize the use of microarrays and database software for genomic, transcriptomic, and proteomic screening to search for a useful clinical assay. The number of molecular pathologic techniques will expand as additional disease-associated mutations are defined.