Follicular dendritic cell-dependent drug resistance of non-Hodgkin lymphoma involves cell adhesion-mediated Bim down-regulation through induction of microRNA-181a

Modeling the crosstalk between malignant B cells and their microenvironment in B-cell lymphomas: challenges and opportunities

B-cell lymphomas are a group of heterogeneous neoplasms resulting from the clonal expansion of mature B cells arrested at various stages of differentiation. Specifically, two lymphoma subtypes arise from germinal centers (GCs), namely follicular lymphoma (FL) and GC B-cell diffuse large B-cell lymphoma (GCB-DLBCL). In addition to recent advances in describing the genetic landscape of FL and GCB-DLBCL, tumor microenvironment (TME) has progressively emerged as a central determinant of early lymphomagenesis, subclonal evolution, and late progression/transformation. The lymphoma-supportive niche integrates a dynamic and coordinated network of immune and stromal cells defining microarchitecture and mechanical constraints and regulating tumor cell migration, survival, proliferation, and immune escape. Several questions are still unsolved regarding the interplay between lymphoma B cells and their TME, including the mechanisms supporting these bidirectional interactions, the impact of the kinetic and spatial heterogeneity of the tumor niche on B-cell heterogeneity, and how individual genetic alterations can trigger both B-cell intrinsic and B-cell extrinsic signals driving the reprogramming of non-malignant cells. Finally, it is not clear whether these interactions might promote resistance to treatment or, conversely, offer valuable therapeutic opportunities. A major challenge in addressing these questions is the lack of relevant models integrating tumor cells with specific genetic hits, non-malignant cells with adequate functional properties and organization, extracellular matrix, and biomechanical forces. We propose here an overview of the 3D in vitro models, xenograft approaches, and genetically-engineered mouse models recently developed to study GC B-cell lymphomas with a specific focus on the pros and cons of each strategy in understanding B-cell lymphomagenesis and evaluating new therapeutic strategies.

A novel patient-derived 3D model recapitulates mantle cell lymphoma lymph node signaling, immune profile and in vivo ibrutinib responses

Mantle cell lymphoma (MCL), a rare and aggressive B-cell non-Hodgkin lymphoma, mainly develops in the lymph node (LN) and creates a protective and immunosuppressive niche that facilitates tumor survival, proliferation and chemoresistance. To capture disease heterogeneity and tumor microenvironment (TME) cues, we have developed the first patient-derived MCL spheroids (MCL-PDLS) that recapitulate tumor oncogenic pathways and immune microenvironment in a multiplexed system that allows easy drug screening, including immunotherapies. MCL spheroids, integrated by tumor B cells, monocytes and autologous T-cells self-organize in disc-shaped structures, where B and T-cells maintain viability and proliferate, and monocytes differentiate into M2-like macrophages. RNA-seq analysis demonstrated that tumor cells recapitulate hallmarks of MCL-LN (proliferation, NF-kB and BCR), with T cells exhibiting an exhaustion profile (PD1, TIM-3 and TIGIT). MCL-PDLS reproduces in vivo responses to ibrutinib and demonstrates that combination of ibrutinib with nivolumab (anti-PD1) may be effective in ibrutinib-resistant cases by engaging an immune response with increased interferon gamma and granzyme B release. In conclusion, MCL-PDLS recapitulates specific MCL-LN features and in vivo responses to ibrutinib, representing a robust tool to study MCL interaction with the immune TME and to perform drug screening in a patient-derived system, advancing toward personalized therapeutic approaches.

Drug Resistance: The Role of Exosomal miRNA in the Microenvironment of Hematopoietic Tumors

Extracellular vesicles (EVs), including exosomes, have an important role thanks to their ability to communicate and exchange information between tumor cells and the tumor microenvironment (TME), and have also been associated with communicating anti-cancer drug resistance (DR). The increase in proliferation of cancer cells alters oxygen levels, which causes hypoxia and results in a release of exosomes by the cancer cells. In this review, the results of studies examining the role of exosomal miRNA in DR, and their mechanism, are discussed in detail in hematological tumors: leukemia, lymphoma, and multiple myeloma. In conclusion, we underline the exosome's function as a possible drug delivery vehicle by understanding its cargo. Engineered exosomes can be used to be more specific for personalized therapy.

Mitochondria dysfunction in circulating tumor cells

Circulating tumor cells (CTCs) represent a subset of heterogeneous cells, which, once released from a tumor site, have the potential to give rise to metastasis in secondary sites. Recent research focused on the attempt to detect and characterize these rare cells in the circulation, and advancements in defining their molecular profile have been reported in diverse tumor species, with potential implications for clinical applications. Of note, metabolic alterations, involving mitochondria, have been implicated in the metastatic process, as key determinants in the transition of tumor cells to a mesenchymal or stemness-like phenotype, in drug resistance, and in induction of apoptosis. This review aimed to briefly analyse the most recent knowledge relative to mitochondria dysfunction in CTCs, and to envision implications of altered mitochondria in CTCs for a potential utility in clinics.

Tumor Microenvironment of Lymphomas and Plasma Cell Neoplasms: Broad Overview and Impact on Evaluation for Immune Based Therapies

Lymphomas and plasma cell neoplasms are a heterogenous group of malignancies derived from lymphocytes. They are a significant cause of patient morbidity and mortality. Advances in morphologic, immunophenotypic and molecular techniques have led to better understanding of the pathogenesis and diagnosis of these neoplasms. Advances in treatment, particularly immune-based therapies, increasingly allow for targeted therapies of these diseases. Mechanistic studies using animal models and clinical trials have revealed the importance of the tumor microenvironment on disease pathogenesis, progression, and response to therapy in these malignancies. Simultaneous progress in diagnostic techniques has made it feasible to generate high-resolution, high-throughput data from the tumor microenvironment with spatial context. As the armamentarium of targeted therapies and diagnostic techniques grows, there is potential to harness these advances to better stratify patients for targeted therapies, including immune-based therapies, in hematologic malignancies.

Serum biomarkers of acute rejection: Towards precision medicine in heart transplant

Despite the important changes in the management of heart transplantation in the recent decades, the use of endomyocardial biopsy is still necessary for the follow-up of these patients. However, this technique has several limitations, the most important being the substantial interobserver variability. In the last years multiple attempts have been made to find non-invasive assays for cardiac allograft surveillance, such as imaging modalities and serum biomarkers. This state-of-the-art review focuses on describing the different serum biomarkers that have been proposed for non-invasive diagnosis of acute rejection and that are paving the way towards precision medicine in the field of heart transplantation.

Treatment resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a highly heterogeneous disease and represents the most common subtype of lymphoma. Although 60-70% of all patients can be cured by the current standard of care in the frontline setting, the majority of the remaining patients will experience treatment resistance and have a poor clinical outcome. Numerous efforts have been made to improve the efficacy of the standard regimen by, for example, dose intensification or adding novel agents. However, these results generally failed to demonstrate significant clinical benefits. Hence, understanding treatment resistance is a pressing need to optimize the outcome of those patients. In this Review, we first describe the conceptual sources of treatment resistance in DLBCL and then provide detailed and up-to-date molecular insight into the mechanisms of resistance to the current treatment options in DLBCL. We lastly highlight the potential strategies for rationally managing treatment resistance from both the preventive and interventional perspectives.

CAM-DR: Mechanisms, Roles and Clinical Application in Tumors

Despite the continuous improvement of various therapeutic techniques, the overall prognosis of tumors has been significantly improved, but malignant tumors in the middle and advanced stages still cannot be completely cured. It is now evident that cell adhesion-mediated resistance (CAM-DR) limits the success of cancer therapies and is a great obstacle to overcome in the clinic. The interactions between tumor cells and extracellular matrix (ECM) molecules or adjacent cells may play a significant role in initiating the intracellular signaling pathways that are associated with cell proliferation, survival upon binding to their ligands. Recent studies illustrate that these adhesion-related factors may contribute to the survival of cancer cells after chemotherapeutic therapy, advantageous to resistant cells to proliferate and develop multiple mechanisms of drug resistance. In this review, we focus on the molecular basis of these interactions and the main signal transduction pathways that are involved in the enhancement of the cancer cells’ survival. Furthermore, therapies targeting interactions between cancer cells and their environment to enhance drug response or prevent the emergence of drug resistance will also be discussed.

Role of Microenvironment in Non-Hodgkin Lymphoma: Understanding the Composition and Biology

Lymphoma microenvironment is a dynamic and well-orchestrated network of various immune and stromal cells that is indispensable for tumor cell survival, growth, migration, immune escape, and drug resistance. Recent progress has enhanced our knowledge of the pivotal role of microenvironment in lymphomagenesis. Understanding the characteristics, functions, and contributions of various components of the tumor niche, along with its bidirectional interactions with tumor cells, is paramount. It offers the potential to identify new therapeutic targets with the ability to restore antitumor immune surveillance and eliminate the protumoral factors contributed by the tumor niche.

miRNAs mediated drug resistance in hematological malignancies

Despite improvements in the therapeutic approaches for hematological malignancies in the last decades, refractory disease still occurs, and cancer drug resistance still remains a major hurdle in the clinical management of these cancer patients. The investigation of this problem has been extensive and different mechanism and molecules have been associated with drug resistance. MicroRNAs (miRNAs) have been described as having an important action in the emergence of cancer, including hematological tumors, and as being major players in their progression, aggressiveness and response to treatments. Moreover, miRNAs have been strongly associated with cancer drug resistance and with the modulation of the sensitivity of cancer cells to a wide array of anticancer drugs. Furthermore, this role has also been reported for miRNAs packaged into extracellular vesicles (EVs-miRNAs), which in turn have been described as essential for the horizontal transfer of drug resistance to sensitive cells. Several studies have been suggesting the use of miRNAs as biomarkers for drug response and clinical outcome prediction, as well as promising therapeutic tools in hematological diseases. Indeed, the combination of miRNA-based therapeutic tools with conventional drugs contributes to overcome drug resistance. This review addresses the role of miRNAs in the pathogenesis of hematological malignances, namely multiple myeloma, leukemias and lymphomas, highlighting their important action (either in their cell-free circulating form or within circulating EVs) in drug resistance and their potential clinical applications.

The Role of Noncoding RNAs in B-Cell Lymphoma

In recent years, emerging evidence has suggested that noncoding RNAs (ncRNAs) participate in nearly every aspect of biological processes and play a crucial role in the genesis and progression of numerous tumors, including B-cell lymphoma. The exploration of ncRNA dysregulations and their functions in B-cell lymphoma provides new insights into lymphoma pathogenesis and is essential for indicating future clinical trials and optimizing the diagnostic and therapeutic strategies. In this review, we summarize the role of ncRNAs in B-cell lymphoma and discuss their potential in clinical applications.

Circulating miR-181a-5p as a new biomarker for acute cellular rejection in heart transplantation

BACKGROUND

Acute cellular rejection (ACR) is a major complication in heart transplantation (HTx). Endomyocardial biopsy is the reference method for early detection of ACR, but a new non-invasive approach is needed. Tentative candidates could be circulating microRNAs. This study aimed to discover and validate microRNAs in serum for ACR detection after HTx.

METHODS

This prospective, observational, single-center study included 121 HTx patients. ACR was graded according to International Society of Heart and Lung Transplantation classification (0R-3R). First, in the discovery phase, microRNA expression profile was carried out in serum samples from patients at pre-rejection, during, and post-rejection time (0R_S1 → 2R_S2` → 0R_S3). Relative expression (2^-∆Cq) of 179 microRNAs per sample was analyzed by reverse transcription quantitative polymerase chain reaction. Second, a microRNA with a significant rise and fall pattern during ACR was selected for the next validation phase, where it was analyzed (reverse transcription quantitative polymerase chain reaction) in serum samples from 2 groups of patients: the no-ACR group (0R grade) and the ACR group (≥2R grade). Finally, a sensitivity analysis (receiver operating characteristic curve) was done to assess microRNA accuracy for ACR detection in HTx.

RESULTS

A total of 21 ACR episodes (0R_S1 → 2R_S2 → 0R_S3) with their respective serum samples (n = 63) were included in the discovery phase. Among the 179 microRNAs analyzed, only miR-181a-5p met the rise and fall criteria. In the validation phase, miR-181a-5p relative expression (2^-∆Cq) in the ACR group (n = 45) was significantly overexpressed (p < 0.0001) vs the no-ACR group (n = 45). miR-181a-5p showed an area under the curve of 0.804 (95% confidence interval: 0.707-0.880); sensitivity and specificity of 78% and 76%, respectively; and a negative predicted value of 98%.

CONCLUSIONS

miR-185a-5p in serum is a candidate as a non-invasive ACR biomarker (area under the curve = 0.80 and negative predicted value = 98%). Thus, this biomarker could reduce the need for endomyocardial biopsies and the associated risks and costs of this invasive procedure.

The Interplay between MicroRNAs and the Components of the Tumor Microenvironment in B-Cell Malignancies

An increased focus is being placed on the tumorigenesis and contexture of tumor microenvironment in hematopoietic and solid tumors. Despite recent clinical revolutions in adoptive T-cell transfer approaches and immune checkpoint blockade, tumor microenvironment is a major obstacle to tumor regression in B-cell malignancies. A transcriptional alteration of coding and non-coding RNAs, such as microRNAs (miRNAs), has been widely demonstrated in the tumor microenvironment of B-cell malignancies. MiRNAs have been associated with different clinical-biological forms of B-cell malignancies and involved in the regulation of B lymphocyte development, maturation, and function, including B-cell activation and malignant transformation. Additionally, tumor-secreted extracellular vesicles regulate recipient cell functions in the tumor microenvironment to facilitate metastasis and progression by delivering miRNA contents to neighboring cells. Herein, we focus on the interplay between miRNAs and tumor microenvironment components in the different B-cell malignancies and its impact on diagnosis, proliferation, and involvement in treatment resistance.

Elucidating the expression and function of Numbl during cell adhesion-mediated drug resistance (CAM-DR) in multiple myeloma (MM)

Background

Cell adhesion-mediated drug resistance (CAM-DR) is a major clinical problem that prevents successful treatment of multiple myeloma (MM). In particular, the expression levels of integrin β1 and its sub-cellular distribution (internalization and trafficking) are strongly associated with CAM-DR development.

Methods

Development of an adhesion model of established MM cell lines and detection of Numbl and Integrinβ1 expression by Western Blot analysis. The interaction between Numbl and Integrinβ1 was assessed by a co-immunoprecipitation (CO-IP) method. Calcein AM assay was performed to investigate the levels of cell adhesion. Finally, the extent of CAM-DR in myeloma cells was measured using cell viability assay and flow cytometry analysis.

Results

Our preliminary date suggest that Numbl is differentially expressed in a cell adhesion model of MM cell lines. In addition to binding to the phosphotyrosine-binding (PTB) domain, the carboxyl terminal of Numbl can also interact with integrin β1 to regulate the cell cycle by activating the pro-survival PI3K/AKT signaling pathway. This study intends to verify and elucidate the interaction between Numbl and integrin β1 and its functional outcome on CAM-DR. We have designed and developed a CAM-DR model using MM cells coated with either fibronectin or bone marrow stromal cells. We assessed whether Numbl influences cell-cycle progression and whether it, in turn, contributes to activation of PI3K/AKT signal pathway through the adjustment of its carboxyl end. Finally, we showed that the interaction of Numbl with integrin β1 promotes the formation of CAM-DR in MM cells.

Conclusions

Our findings elucidated the specific molecular mechanisms of CAM-DR induction and confirmed that Numbl is crucial for the development of CAM-DR in MM cells.

Altered expression of miR-181 affects cell fate and targets drug resistance-related mechanisms

MicroRNAs (miRNAs) are non-coding transcripts which regulate genetic and epigenetic events by interfering with mRNA translation. miRNAs are involved in regulation of cell fate due to their ability of interfering with physiological or pathological processes. In this review paper, we evaluate the role of miR-181 family members as prognostic or diagnostic markers or therapeutic targets in malignant pathologies in connection with the main hallmarks of cancer that are modulated by the family. Also, we take over the dual role of this family in dependency with the tumour suppressor and oncogenic features presented in cell and cancer type specific manner. Restoration of the altered expression levels contributes to the activation of cell death pathways or to a reduction in the invasion and migration mechanism; moreover, the mechanism of drug resistance is also modulated by miR-181 sequences with important applications in therapeutic strategies for malignant cells sensitisation. Overall, the main miR-181 family regulatory mechanisms are presented in a cancer specific context, emphasizing the possible clinical application of this family in terms of novel diagnosis and therapy approaches.

miR-182 contributes to cell adhesion-mediated drug resistance in multiple myeloma via targeting PDCD4

miR-182 is a well-described oncogenic miRNA playing a crucial role in the development of many malignancies. However, the role of miR-182 in multiple myeloma (MM) remains unclear. Here, we demonstrate that adhesion of H929 and MM.1S cells to fibronectin could induce miR-182 expression and decrease PDCD4 expression. Furthermore, miR-182 was found to negatively regulate PDCD4 expression in H929 and MM.1S cells. In addition, PDCD4 down-regulation was required for cell adhesion-mediated drug resistance (CAM-DR). Intriguingly, miR-182 up-regulation could promote CAM-DR in H929 and MM.1S cells. Moreover, miR-182 up-regulation and PDCD4 down-regulation enhanced AKT phosphorylation at Ser473 in both H929 and MM.1S cells. Our data suggest that cell adhesion-mediated miR-182 up-regulation and PDCD4 down-regulation may confer drug resistance via enhancing AKT phosphorylation at Ser473.

[MicroRNA-138 regulates cell adhesion-mediated drug resistance phenotype by targeting SGTA in non-Hodgkin's lymphoma]

目的

分析microRNA-138（miR-138）靶向调节小谷氨酰胺三角四肽重复区蛋白α（SGTA）对非霍奇金淋巴瘤（NHL）细胞黏附介导的耐药（cell adhesion-mediated drug resistance, CAM-DR）的影响。

方法

以HS-5细胞或纤连蛋白（FN）构建NHL细胞黏附模型；Western blotting与RQ-PCR分析miR-138对SGTA蛋白及mRNA表达的影响；双荧光素酶报告基因活性检测分析miR-138对SGTA mRNA 3′UTR活性的影响；分别用miR-138下调慢病毒载体（Lv-shmiR-138）、miR-138过表达慢病毒载体（Lv-miR-138）、对照慢病毒载体（Lv-Ctrl）感染Daudi及OCI-Ly8细胞，分析miR-138对细胞周期、黏附能力及CAM-DR的影响；收集35例弥漫大B细胞淋巴瘤患者的石蜡组织标本，分析miR-138的表达情况及其与疾病进展和耐药关系。

结果

①NHL细胞与FN或HS-5细胞黏附培养后miR-138表达水平显著高于悬浮培养组（P值均<0.05）。②下调miR-138的表达可增强SGTA蛋白的表达水平（P值均<0.05），而对SGTA mRNA的表达水平无显著影响（P值均>0.05）。③转染野生型SGTA 3′UTR载体时，过表达miR-138可显著抑制荧光素酶报告基因活性（0.73±0.03对1.00±0.02，t=0.914，P=0.002）；而转染结合位点突变的突变型载体时，过表达miR-138不能显著改变报告基因活性（0.93±0.04对1.00±0.02，t=1.375，P=0.241）。④在悬浮及黏附培养状态下，过表达miR-138可显著诱导Daudi及OCI-Ly8细胞G₁期停滞（P值均<0.05）。⑤下调miR-138的表达对Daudi及OCI-Ly8细胞的黏附能力均无显著影响（P值均>0.05）。⑥在悬浮培养状态下调miR-138的表达时，多柔比星诱导细胞死亡的比例显著下降，而在黏附培养状态下调miR-138的表达，多柔比星诱导细胞死亡的比例显著上升（P值均<0.05）。⑦miR-138在进展及稳定患者中的表达水平显著高于完全缓解以及部分缓解患者，差异具有统计学意义（9.72±1.11对3.06±0.22，t=9.144，P<0.001）。

结论

在黏附微环境中miR-138可通过靶向抑制SGTA诱导细胞周期G₁期停滞促进CAM-DR进程。

New concepts in follicular lymphoma biology: From BCL2 to epigenetic regulators and non-coding RNAs

The molecular pathogenesis of follicular lymphoma (FL) was partially revealed 3 decades ago, with the discovery of the translocation that brings BCL2 under the influence of immunoglobulin heavy chain enhancers in a vast majority of cases. Despite the importance of this seminal observation, it has become increasingly clear that additional genetic alterations need to occur to trigger neoplastic transformation and disease progression. The evolution of FL involves developmental arrest and disruption of the normal function of one or more of epigenetic regulators including KMT2D/MLL2, EZH2, CBP/CREBBP, p300/EP300, and HIST1H1 in >95% of cases. B-cells "arrested" in germinal centers acquire dozens of additional genetic aberrations that influence key pathways controlling their physiological development including B Cell Receptor (BCR) signaling, PI3K/AKT, TLR, mTOR, NF-κB, JAK/STAT, MAPK, CD40/CD40L, chemokine, and interleukin signaling. Additionally, most cases of FL do not result from linear accumulation of genomic aberrations, but rather evolve from a common progenitor cell population by diverse evolution, creating multiple FL subclones in one patient. Moreover, one of the subclones might acquire a combination of aberrations involving genes controlling cell survival and proliferation including MDM2, CDKN2A/B, BCL6, MYC, TP53, β2M, FOXO1, MYD88, STAT3, or miR-17-92, and this can lead to the transformation of an initially indolent FL to an aggressive lymphoma (2%-3% risk per year). The complexity of the disease is also underscored by the importance of its interactions with the microenvironment that can substantially influence disease development and prognosis. Interpreting individual aberrations in relation to their impact on normal processes, their frequency, position in the disease evolution, and the consequences of their (co)occurrence, are the basis for understanding FL pathogenesis. This is necessary for the identification of patients with risk of early progression or transformation, for the development of novel targeted therapies, and for personalized treatment approaches. In this review, we summarize recent knowledge of molecular pathways and microenvironmental components involved in FL biology, and discuss them in the context of physiological B-cell development, FL evolution, and targeted therapies.

Microenvironment Cell Contribution to Lymphoma Immunity

Lymphoma microenvironment is a complex system composed of stromal cells, blood vessels, immune cells as well as extracellular matrix, cytokines, exosomes, and chemokines. In this review, we describe the function, localization, and interactions between various cellular components. We also summarize their contribution to lymphoma immunity in the era of immunotherapy. Publications were identified from searching Pubmed. Primary literature was carefully evaluated for replicability before incorporating into the review. We describe the roles of mesenchymal stem/stromal cells (MSCs), lymphoma-associated macrophages (LAMs), dendritic cells, cytotoxic T cells, PD-1 expressing CD4+ tumor infiltrating lymphocytes (TILs), T-cells expressing markers of exhaustion such as TIM-3 and LAG-3, regulatory T cells, and natural killer cells. While it is not in itself a cell, we also include a brief overview of the lymphoma exosome and how it contributes to anti-tumor effect as well as immune dysfunction. Understanding the cellular players that comprise the lymphoma microenvironment is critical to developing novel therapeutics that can help block the signals for immune escape and promote tumor surveillance. It may also be the key to understanding mechanisms of resistance to immune checkpoint blockade and immune-related adverse events due to certain types of immunotherapy.

p110α Inhibition Overcomes Stromal Cell-Mediated Ibrutinib Resistance in Mantle Cell Lymphoma

Acquired resistance to cancer drugs is common, also for modern targeted drugs like the Bruton tyrosine kinase (BTK) inhibitor ibrutinib, a new drug approved for the treatment of the highly aggressive and relapsing mantle cell lymphoma (MCL). The tumor microenvironment often impacts negatively on drug response. Here, we demonstrate that stromal cells protect MCL cells from ibrutinib-induced apoptosis and support MCL cell regrowth after drug removal by impairing ibrutinib-mediated downregulation of PI3K/AKT signaling. Importantly, the stromal cell-mediated ibrutinib resistance was overcome in vitro by inhibiting AKT activity using the PI3K catalytic p110α subunit-specific inhibitor BYL719. This was seen both for MCL cell lines and primary MCL cells. Furthermore, inhibition of p110α activity by BYL719 potentiated the ability of ibrutinib to inhibit MCL tumor growth in vivo in a mouse xenograft model. The stromal cell-mediated ibrutinib resistance was found to be due to a direct interaction with MCL cells and involves the integrin VLA-4, as disrupting stromal cell-MCL cell interaction using a VLA-4 blocking antibody abrogated the ibrutinib resistance. This suggests that combined treatment with ibrutinib and a p110α inhibitor, alternatively by disrupting stromal cell-MCL cell interaction, may be a promising therapeutic strategy to overcome stromal cell-mediated ibrutinib resistance in MCL. Mol Cancer Ther; 17(5); 1090-100. ©2018 AACR.

The degree of overlap between the follicular dendritic cell meshwork and tumor cells in mantle cell lymphoma is associated with prognosis

This study concerning mantle cell lymphoma (MCL) investigated retrospectively an association between patient prognosis and the percentage of the total number of lymphoma cells found in the follicular dendritic cell (FDC) meshwork, that is, the degree of overlap of lymphoma cells. Two hundred and nine MCL patients were apportioned to grades I-III, in which the CD21-positive FDC meshwork covered ≤50%, 51%-89%, and ≥90% of the tumor area, respectively. Significant differences among the grades (all, P < 0.01) were found in the following: duration of disease (from onset of clinical manifestation to diagnosis); clinical staging; extranodal involvement (non-lymphoid organs); histological subtype; and Ki-67 proliferation index (PI). After removing the aggressive variants, the overall survival rates of grade I (n = 92) and II (n = 57) patients were similar. The overall survival rates of grade III (n = 46) patients differed from that of grade I + II patients (P < 0.01). The grades negatively correlated with the Ki-67 PI value (r = -0.234, P = 0.001). At each grade the OSR of patients with Ki-67 PI ≤30% was similar to that of patients with Ki-67 >30%. In the Ki-67 PI ≤30% group, the OSRs of the patients differed significantly among the grades. In the Ki-67 >30% group the OSRs of the grades were similar. The results of multivariate Cox regression analysis showed that the degree of overlap, age and Ki-67 PI was the independent prognostic factors of the OSRs of MCL patients. Our data suggests that MCL patients in whom there was a high degree of overlap between the FDC meshwork and tumor area have a better clinical prognosis. The degree of overlap correlates well with the Ki-67 PI, which can be used to predict the prognosis of patients.

Resistance to Ibrutinib in B Cell Malignancies: One Size Does Not Fit All

Ibrutinib resistance, as a result of coordinated rewiring of signaling networks and enforced tumor microenvironment (TME)-lymphoma interactions, drives unrestrained proliferation and disease progression. To combat resistance mechanisms, we must identify the compensatory resistance pathways and the central modulators of reprogramming events. Targeting the transcriptome and kinome reprogramming of lymphoma cells represents a rational approach to mitigate ibrutinib resistance in B cell malignancies. However, with the apparent heterogeneity and plasticity of tumors shown in therapy response, a one size fits all approach may be unattainable. To this end, a reliable and real-time drug screening platform to tailor effective individualized therapies in patients with B cell malignancies is warranted. Here, we describe the complexity of ibrutinib resistance in B cell lymphomas and the current approaches, including a drug screening assay, which has the potential to further explore the mechanisms of ibrutinib resistance and to design effective individualized combination therapies to overcome resistance and disable aggressive lymphomas (see Outstanding Questions).

miR-181a-5p suppresses invasion and migration of HTR-8/SVneo cells by directly targeting IGF2BP2

Pre-eclampsia is a pregnancy-related disease that may cause maternal, neonatal and fetal morbidity and mortality and exists in 3–5% of pregnancies worldwide. The discovery of dysregulated microRNAs and their roles in placental development has provided a new avenue for elucidating the mechanism involved in this pregnancy-specific disorder. Here, the roles of human miR-181a-5p, a microRNA that is increased in both the plasma and placenta of severe pre-eclamptic patients, in invasion and migration of trophoblasts were investigated. Ectopic-expression of miR-181a-5p impaired the invasion and migration of HTR-8/SVneo cells, whereas miR-181a-5p inhibition had the opposite effects. IGF2BP2, which harbors a highly conserved miR-181a-5p-binding site within its 3ʹ-UTR, was identified to be directly inhibited by miR-181a-5p. Moreover, siRNAs targeting IGF2BP2 imitated the effects of overexpressed miR-181a-5p on HTR-8/SVneo cell invasion and migration, whereas restoring IGF2BP2 expression by overexpressing a plasmid encoding IGF2BP2 partially reversed the studied inhibitory functions of miR-181a-5p. Thus, we demonstrated here that miR-181a-5p suppresses the invasion and migration of cytotrophoblasts, and its inhibitory effects were at least partially mediated by the suppression of IGF2BP2 expression, thus shedding new light on the roles of miR-181a-5p in the pathogenesis of severe pre-eclampsia.

Bridging Autism Spectrum Disorders and Schizophrenia through inflammation and biomarkers - pre-clinical and clinical investigations

In recent years, evidence supporting a link between inflammation and neuropsychiatric disorders has been mounting. Autism spectrum disorders (ASD) and schizophrenia share some clinical similarities which we hypothesize might reflect the same biological basis, namely, in terms of inflammation. However, the diagnosis of ASD and schizophrenia relies solely on clinical symptoms, and to date, there is no clinically useful biomarker to diagnose or monitor the course of such illnesses.

The focus of this review is the central role that inflammation plays in ASD and schizophrenia. It spans from pre-clinical animal models to clinical research and excludes in vitro studies. Four major areas are covered: (1) microglia, the inflammatory brain resident myeloid cells, (2) biomarkers, including circulating cytokines, oxidative stress markers, and microRNA players, known to influence cellular processes at brain and immune levels, (3) effect of anti-psychotics on biomarkers and other predictors of response, and (4) impact of gender on response to immune activation, biomarkers, and response to anti-psychotic treatments.

A SNP in pri-miR-10a is associated with recurrent spontaneous abortion in a Han-Chinese population

MicroRNA-10a (miR-10a) has a wide range of functions in nearly all mammalian tissues and is involved in the occurrence of many diseases. However, it remains unknown whether miR-10a is associated with human recurrent spontaneous abortion (RSA). In this study, we found that rs3809783 A > T in miR-10a coding region was significantly associated with the increase of the risk of human unexplained RSA (URSA) acquisition in a Han-Chinese population. The T allele of rs3809783 hindered the production of mature miR-10a. A to T substitution in miR-10a rs3809783 repressed cell proliferation and migratory capacity. Further investigation discovered that Bcl-2-interacting mediator (Bim) was the functional target of miR-10a and inversely regulated Bim expression. Dual-luciferase assay indicated that A allele in miR-10a rs3809783 could more effectively suppress Bim expression than T allele. In addition, A to T substitution in miR-10a rs3809783 attenuated the sensibility of cells to progesterone and its antagonist mifepristone. Collectively, our data suggest that rs3809783 A > T in pri-miR-10a may be conductive to the genetic predisposition to RSA by disrupting the production of mature miR-10a and reinforcing the expression of Bim.

Rational targeted therapies to overcome microenvironment-dependent expansion of mantle cell lymphoma

Mantle cell lymphoma (MCL) accumulates in lymphoid organs, but disseminates early on in extranodal tissues. Although proliferation remains located in lymphoid organs only, suggesting a major role of the tumor ecosystem, few studies have assessed MCL microenvironment. We therefore cocultured primary circulating MCL cells from 21 patients several weeks ex vivo with stromal or lymphoid-like (CD40L) cells to determine which interactions could support their proliferation. We showed that coculture with lymphoid-like cells, but not stromal cells, induced cell-cycle progression, which was amplified by MCL-specific cytokines (insulin-like growth factor-1, B-cell activating factor, interleukin-6, interleukin-10). Of interest, we showed that our model recapitulated the MCL in situ molecular signatures (ie, proliferation, NF-κB, and survival signatures). We further demonstrated that proliferating MCL harbored an imbalance in Bcl-2 family expression, leading to a consequent loss of mitochondrial priming. Of interest, this loss of priming was overcome by the type II anti-CD20 antibody obinutuzumab, which counteracted Bcl-x_L induction through NF-κB inhibition. Finally, we showed that the mitochondrial priming directly correlated with the sensitivity toward venetoclax and alkylating drugs. By identifying the microenvironment as the major support for proliferation and drug resistance in MCL, our results highlight a selective approach to target the lymphoma niche.

Expression of far upstream element binding protein 1 in B‑cell non‑Hodgkin lymphoma is correlated with tumor growth and cell‑adhesion mediated drug resistance

Cell adhesion‑mediated drug resistance (CAM‑DR) remains a major obstacle to the effectiveness of chemotherapeutic treatment of lymphoma. Far upstream element binding protein 1 (FBP1) is a multifunctional protein that is highly expressed in proliferating cells of several solid neoplasms; however, its expression and biological function in B‑cell lymphoma is largely unknown. FBP1 expression in both reactive lymphoid tissues and several B‑cell lymphomas, including follicular lymphoma and diffuse large B‑cell lymphoma were detected by immunohistochemistry analysis. FBP1 expression in B‑cell lymphoma was also associated with poor survival outcomes. Functionally, small interfering RNA‑mediated silencing of FBP1 was able to inhibit the proliferation of B‑cell lymphoma cells, resulting in G0/G1 phase cell cycle arrest. Furthermore, results of a cell adhesion assay demonstrated that adhesion to fibronectin or bone marrow stromal cells induced FBP1 expression, which in turn facilitated cell adhesion. Finally, FBP1 knockdown reversed CAM‑DR. These findings support a role for FBP1 in non‑Hodgkin lymphoma cell proliferation, adhesion and drug resistance, and may lead to the generation of a novel therapeutic approach targeting this molecule.

Involvement of microRNA-181a and Bim in a rat model of retinal ischemia-reperfusion injury

AIM

To investigate the changes in the expression of microRNA-181a (miR-181a) and Bim in a rat model of retinal ischemia-reperfusion (RIR), to explore their target relationship in RIR and their involvement in regulating apoptosis of retinal ganglion cells (RGCs).

METHODS

Target gene prediction for miR-181a was performed with the aid of bioinformatics and Bim was identified as a potential target gene of miR-181a. A rat model of RIR was created by increasing the intraocular pressure. RGCs in the flatmounted retinas were labeled with Brn3, a marker for alive RGCs, by immunofluorescent staining. The changes in the number of RGCs after RIR were recorded. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to determine the expression level of miR-181a in the retina. Bim/Brn3 double immunofluorescence was used to detect the localization of Bim. The expression of Bim in the retina was determined with the aids of Western blot and qRT-PCR.

RESULTS

Compared with the negative control group, the density of RGCs was significantly lower in the ischemia/reperfusion (I/R)-24h and I/R-72h groups (P<0.001). The expression level of miR-181a started to decrease at 0h after RIR, and further decreased at 24h and 72h compared with the negative control group (P<0.001). Bim was significantly upregulated at 12h after RIR (P<0.05) and reached peak at 24, 72h compared with the negative control group (P<0.01). Pearson correlation analysis showed that the expression level of Bim was negatively correlated with the expression level of miR-181a and the density of RGCs.

CONCLUSION

Bim may be a potential target gene of miR-181a. Both miR-181a and Bim are involved in RGCs death in RIR. RIR may promote RGCs apoptosis in the retina via downregulation of miR-181a and its inhibition on Bim expression.

[The expression and functional study of miR-181a in pediatric acute lymphoblastic leukemia]

OBJECTIVE

To investigate the expression of miR-181a in bone marrow (BM) samples of pediatric acute lymphoblastic leukemia (ALL) and explore the mechanism of miR-181a on ALL cell line CCRF-CEM and drug resistance cell line CEM-C1.

METHODS

BM samples were obtained from 18 patients where matched samples at initial diagnosis and first BM relapse or complete remission were available. BM samples and cord blood samples (normal controls) were used to confirm the differential expression of miRNA-181a by quantitative real-time polymerase chain reaction (qRT-PCR). The expressions of miR-181a in both CCRF-CEM and its mutidrug-resistant counterpart CEM-C1 cells were also detected. Then, CCK-8 assay was performed to quantify the effects of miR-181a on CEM-C1 and CCRF-CEM cells growth and viability.

RESULTS

Up-regulated miR-181a with higher fold changes in both initial diagnosis (4.84 ± 2.71, 7.58 ± 2.50) and relapsed samples (6.53 ± 2.20) compared to normal controls (1.41 ± 0.53) (P=0.017, 0.000, 0.001, respectively) were observed, whereas the miR-181a expression in the samples of CR (1.35 ± 0.35) compared to normal control showed no significant difference (P=0.863). The miR-181a expression level was higher in CEM-C1 cells (-4.39 ± 0.08) than of in CCRF-CEM cells (-2.32 ± 0.03) (P=0.000). CCK-8 assay revealed that suppression of miR-181a in CEM-C1 cells by transfecting the specific inhibitor of miR-181a led to significantly higher cellular proliferation inhibition rate than negative control cells (P<0.05), IC50 were 30.61 ng/ml and 2 255.00 ng/ml with RI as 73.67. While increased miR-181a in CCRF-CEM cells led to significantly lower CPIR than negative control cells (P<0.01), IC50 were 126.60 ng/ml and 1.34 ng/ml with RI as 94.26.

CONCLUSION

Upregulation of miR-181a might play an important role in the development of drug resistance in CEM-C1 cells, and knockdown of miR-181a could sensitize CEM-C1 cells to camptothecin; Meanwhile increased expression of miR-181a could promote CCRF-CEM drug resistance. These results suggested that suppression of miR-181a expression might provide a promising therapeutic in drug resistance of leukaemia.

Oncogenic MicroRNAs: Key Players in Malignant Transformation

MicroRNAs (miRNAs) represent a class of non-coding RNAs that exert pivotal roles in the regulation of gene expression at the post-transcriptional level. MiRNAs are involved in many biological processes and slight modulations in their expression have been correlated with the occurrence of different diseases. In particular, alterations in the expression of miRNAs with oncogenic or tumor suppressor functions have been associated with carcinogenesis, malignant transformation, metastasis and response to anticancer treatments. This review will mainly focus on oncogenic miRNAs whose aberrant expression leads to malignancy.

Pyruvate kinase isoform M2 (PKM2) participates in multiple myeloma cell proliferation, adhesion and chemoresistance

Cell adhesion mediated drug resistance (CAM-DR) remains the major barrier in human multiple myeloma (MM) therapy. In the present study, we aimed at investigating the role of pyruvate kinase isoform M2 (PKM2) in MM CAM-DR. We determined that PKM2 expression was positively correlated with cell proliferation and knockdown of PKM2 contributed to the increased cell adhesion rate in MM. The enhancement in the adhesion of MM cells to fibronectin or the bone marrow stroma cell line HS-5 cells translated to an increased CAM-DR phenotype. Importantly, we showed that this CAM-DR phenotype was correlated with the phosphorylation of Akt and ERK in MM cells. Taken together, our data shed new light on the molecular mechanism of CAM-DR in MM, and targeting PKM2 may be a novel therapeutic approach for improving the effectiveness of chemotherapy in MM.

MicroRNA181a Is Overexpressed in T-Cell Leukemia/Lymphoma and Related to Chemoresistance

MicroRNAs (miRs) play an important role in tumorogenesis and chemoresistance in lymphoid malignancies. Comparing with reactive hyperplasia, miR181a was overexpressed in 130 patients with T-cell leukemia/lymphoma, including acute T-cell lymphoblastic leukemia (n = 32), T-cell lymphoblastic lymphoma (n = 16), peripheral T-cell lymphoma, not otherwise specified (n = 45), anaplastic large cell lymphoma (n = 15), and angioimmunoblastic T-cell lymphoma (n = 22). Irrespective to histological subtypes, miR181a overexpression was associated with increased AKT phosphorylation. In vitro, ectopic expression of miR181a in HEK-293T cells significantly enhanced cell proliferation, activated AKT, and conferred cell resistance to doxorubicin. Meanwhile, miR181a expression was upregulated in Jurkat cells, along with AKT activation, during exposure to chemotherapeutic agents regularly applied to T-cell leukemia/lymphoma treatment, such as doxorubicin, cyclophosphamide, cytarabine, and cisplatin. Isogenic doxorubicin-resistant Jurkat and H9 cells were subsequently developed, which also presented with miR181a overexpression and cross-resistance to cyclophosphamide and cisplatin. Meanwhile, specific inhibition of miR181a enhanced Jurkat and H9 cell sensitivity to chemotherapeutic agents, further indicating that miR181a was involved in acquired chemoresistance. Collectively, miR181a functioned as a biomarker of T-cell leukemia/lymphoma through modulation of AKT pathway. Related to tumor cell chemoresistance, miR181a could be a potential therapeutic target in treating T-cell malignancies.

ENO1 promotes tumor proliferation and cell adhesion mediated drug resistance (CAM-DR) in Non-Hodgkin's Lymphomas

Enolases are glycolytic enzymes responsible for the ATP-generated conversion of 2-phosphoglycerate to phosphoenolpyruvate. In addition to the glycolytic function, Enolase 1 (ENO1) has been reported up-regulation in several tumor tissues. In this study, we investigated the expression and biologic function of ENO1 in Non-Hodgkin's Lymphomas (NHLs). Clinically, by western blot analysis we observed that ENO1 expression was apparently higher in diffuse large B-cell lymphoma than in the reactive lymphoid tissues. Subsequently, immunohistochemical staining of 144 NHLs suggested that the expression of ENO1 was significantly lower in the indolent lymphomas compared with the progressive lymphomas. Further, we identified ENO1 as an independent prognostic factor, and it was significantly correlated with overall survival of NHL patients. In addition, we found that ENO1 could promote cell proliferation, regulate cell cycle associated gene and PI3K/AKT signaling pathway in NHLs. Finally, we verified that ENO1 participated in the process of lymphoma cell adhesion mediated drug resistance (CAM-DR). Adhesion to FN or HS5 cells significantly protected OCI-Ly8 and Daudi cells from cytotoxicity compared with those cultured in suspension, and these effects were attenuated when transfected with ENO1-siRNA. Based on the study, we propose that inhibition of ENO1 expression may be a novel strategy for therapy for NHLs patients, and it may be a target for drug resistance.

[Advances in tumor chemo-resistance regulated by MicroRNA]

Chemotherapy is one of the primary treatment for malignant tumors. Tumor multidrug resistance (MDR) is a major cause of clinical failure of chemotherapy; however the mechanisms of chemo-resistance have not been fully elucidated. Recently, microRNA is one of the new hotspots in life science. MicroRNA regulates the expression of genes and plays roles a series of life events by post-transcriptional regulations, including cell proliferation, apoptosis, fat metabolism, nervous development, hormone secretion, tumor vessels generation, stem cell differentiation, tumor cell invasion and metastasis, and other physiological and pathological processes. Recent studies show that microRNA regulates the expression of multiple genes with high efficiency and specificity. The abnormal regulation of target genes by microRNA is responsible for tumor chemo-resistance, this may be an important component of the complexity of the regulation of chemo-resistance. Therefore, the study of microRNA and tumor drug resistance has profound practical significance. In this review, recent studies of tumor drug resistance, regulation of tumor drug resistance by microRNA, and microRNA as a potential target for tumor drug resistance therapy are reviewed.

MicroRNAs as mediators and communicators between cancer cells and the tumor microenvironment

Cancer cells grow in an environment comprised of multiple components that support tumor growth and contribute to therapy resistance. Major cell types in the tumor microenvironment are fibroblasts, endothelial cells and infiltrating immune cells all of which communicate with cancer cells. One way that these cell types promote cancer progression is by altering the expression of microRNAs (miRNAs), small noncoding RNAs that negatively regulate protein expression, either in the cancer cells or in the associated normal cells. Changes in miRNA expression can be brought about by direct interaction between the stromal cells and cancer cells, by paracrine factors secreted by any of the cell types or even through direct communication between cells through secreted miRNAs. Understanding the role of miRNAs in the complex interactions between the tumor and cells in its microenvironment is necessary if we are to understand tumor progression and devise new treatments.

Shaping of the tumor microenvironment: Stromal cells and vessels

Lymphomas develop and progress in a specialized tissue microenvironment such as bone marrow as well as secondary lymphoid organs such as lymph node and spleen. The lymphoma microenvironment is characterized by a heterogeneous population of stromal cells, including fibroblastic reticular cells, nurse-like cells, mesenchymal stem cells, follicular dendritic cells, and inflammatory cells such as macrophages, T- and B-cells. These cell populations interact with the lymphoma cells to promote lymphoma growth, survival and drug resistance through multiple mechanisms. Angiogenesis is also recognized as an important factor associated with lymphoma progression. In recent years, we have learned that the interaction between the malignant and non-malignant cells is bidirectional and resembles, at least in part, the pattern seen between non-neoplastic lymphoid cells and the normal microenvironment of lymphoid organs. A summary of the current knowledge of lymphoma microenvironment focusing on the cellular components will be reviewed here.

Connexin 43 communication channels in follicular dendritic cell development and in follicular lymphomas

Follicular dendritic cells (FDC) show homo- and heterocellular metabolic coupling through connexin 43 (Cx43) gap junctions and support B cell selection and maturation in germinal centers. In follicular lymphomas B cells escape apoptosis while FDC develop abnormally. Here we tested Cx43 channels in reactive FDC development and follicular lymphomas. In culture, the treatment of FDC-B cell clusters (resembling to “ex vivo” germinal centers) with Gap27 peptide, mimicking the 2nd extracellular loop of Cx43 protein, significantly impaired FDC-B cell cluster formation and cell survival. In untreated cultures of intact clusters, cell proliferation showed a moderate reduction. In tissues, Cx43 protein levels run parallel with the density of FDC both in reactive germinal centers and in malformed follicles of follicular lymphomas and showed strong upregulation in newly generated and/or degrading bi-/multinuclear FDC of rudimentary processes. However, the inverse correlation between Cx43 expression and B cell proliferation seen in reactive germinal centers was not detected in follicular lymphomas. Furthermore, Cx43 levels were not associated with either lymphoma grade or bone marrow involvement. Our results suggest that Cx43 channels are critical in FDC and “ex vivo” germinal center development and in the persistence of FDC in follicular lymphomas but do not affect tumor progression.

Histamine-releasing factor/translationally controlled tumor protein plays a role in induced cell adhesion, apoptosis resistance and chemoresistance in non-Hodgkin lymphomas

Mounting evidence has proved that cellular adhesion confers resistance to chemotherapy in multiple lymphomas. The molecular mechanism underlying cell adhesion-mediated drug resistance (CAM-DR) is, however, poorly understood. In this study, we investigated the expression and biologic function of histamine-releasing factor (HRF) in non-Hodgkin lymphomas (NHLs). Clinically, by immunohistochemistry analysis we observed obvious up-regulation of HRF in NHLs including diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and natural killer (NK)/T-cell lymphoma. Functionally, overexpression and knockdown of HRF demonstrated the antiapoptotic effect of HRF in NHL cells, which may be associated with activation of the p-CREB/BCL-2 signaling pathway. Moreover, cell adhesion assay demonstrated that adhesion to fibronectin (FN) or HS-5 up-regulated HRF expression, while knockdown of HRF resulted in decreased cell adhesion, which led to reversed CAM-DR. Our finding supports the role of HRF in NHL cell apoptosis, adhesion and drug resistance, and may provide a clinical therapeutic target for CAM-DR in NHL.

MicroRNAs in B-cells: from normal differentiation to treatment of malignancies

MicroRNAs (miRNAs) are small non-coding RNAs that play important post-transcriptional regulatory roles in a wide range of biological processes. They are fundamental to the normal development of cells, and evidence suggests that the deregulation of specific miRNAs is involved in malignant transformation due to their function as oncogenes or tumor suppressors. We know that miRNAs are involved in the development of normal B-cells and that different B-cell subsets express specific miRNA profiles according to their degree of differentiation. B-cell-derived malignancies contain transcription signatures reminiscent of their cell of origin. Therefore, we believe that normal and malignant B-cells share features of regulatory networks controlling differentiation and the ability to respond to treatment. The involvement of miRNAs in these processes makes them good biomarker candidates. B-cell malignancies are highly prevalent, and the poor overall survival of patients with these malignancies demands an improvement in stratification according to prognosis and therapy response, wherein we believe miRNAs may be of great importance. We have critically reviewed the literature, and here we sum up the findings of miRNA studies in hematological cancers, from the development and progression of the disease to the response to treatment, with a particular emphasis on B-cell malignancies.

MicroRNAs in B-cell lymphomas: how a complex biology gets more complex

MicroRNAs (miRNAs) represent important regulators of gene expression besides transcriptional control. miRNA regulation can be involved in the cell developmental fate decisions, but can also have more subtle roles in buffering stochastic fluctuations in gene expression. They participate in pathways fundamental to B-cell development like B-cell receptor (BCR) signalling, B-cell migration/adhesion, cell-cell interactions in immune niches, and the production and class-switching of immunoglobulins. miRNAs influence B-cell maturation, generation of pre-, marginal zone, follicular, B1, plasma and memory B cells. In this review, we discuss miRNAs with essential functions in malignant B-cell development (such as miR-150, miR-155, miR-21, miR-34a, miR-17-92 and miR-15-16). We also put these miRNAs in the context of normal B-cell differentiation, as this is intimately connected to neoplastic B-cell development. We review miRNAs' role in the most common B-cell malignancies, including chronic lymphocytic leukaemia (CLL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) and mantle cell lymphoma (MCL). We focus on miR-contribution to the regulation of important signalling pathways (such as NF-κB, PI3K/AKT and TGF-β), BCR signalling and its modulators (such as PTEN, SHIP-1, ZAP-70, GAB1 and BTK), anti- and pro-apoptotic proteins (such as BCL2, MCL1, TCL1, BIM, p53 and SIRT1) and transcription factors (such as MYC, MYB, PU.1, FOXP1 and BCL6). We also discuss the association of miRNAs' expression levels with the patients' survival and response to therapy, summarizing their potential use as predictive and prognostic markers. Importantly, the targeting of miRNAs (like use of anti-miR-155 or miR-34a mimic) could provide a novel therapeutic approach as evidenced by tumour regression in xenograft mouse models and initial promising data from clinical trials.

Role of microRNAs on therapy resistance in Non-Hodgkin's lymphoma

Non-Hodgkin's lymphoma (NHL) is a heterogeneous group of malignancies that originate in lymphatic hematopoietic tissue. Chemotherapy has been used as the main therapy for NHL all the time, and local radiotherapy is also a necessary approach to supplementary treatment. However, resistance of tumor cells to chemo- and radiotherapy often prevent a successful long-term treatment of NHL. MicroRNAs (miRNAs) are a class of approximately 22-nucleotide endogenous non-coding RNAs that play an important regulatory role in gene expression, involving in the process of cell proliferation and differentiation. Alterations of miRNAs have been reported in a variety of human cancers, such as lymphomas, and will critically influence the tumor development and progression. Recently, there is increasing evidence that miRNAs could also influence sensitivity of tumor cells to chemo- and radiotherapy, revealing a crucial role of microRNAs in resistance to anticancer treatment. Therefore, understanding the role of miRNAs in chemo- and radio-resistance of tumor and targeting specific miRNAs will open novel avenues for lymphoma treatment and improve the prognosis of NHL patients. This review outlines the role of miRNAs associated with chemo-and radiotherapy resistance in NHL.

The tumour microenvironment in B cell lymphomas

B cell lymphomas are cancers that arise from cells that depend on numerous highly orchestrated interactions with immune and stromal cells in the course of normal development. Despite the recent focus on dissecting the genetic aberrations within cancer cells, it has been increasingly recognized that tumour cells retain a range of dependence on interactions with the non-malignant cells and stromal elements that constitute the tumour microenvironment. A fundamental understanding of these interactions gives insight into the pathogenesis of most B cell lymphomas and, moreover, identifies novel therapeutic opportunities for targeting oncogenic pathways, both now and in the future.

microRNAs in cancer cell response to ionizing radiation

SIGNIFICANCE

microRNAs (miRNA) have been characterized as master regulators of the genome. As such, miRNAs are responsible for regulating almost every cellular pathway, including the DNA damage response (DDR) after ionizing radiation (IR). IR is a therapeutic tool that is used for the treatment of several types of cancer, yet the mechanism behind radiation response is not fully understood.

RECENT ADVANCES

It has been demonstrated that IR can alter miRNA expression profiles, varying greatly from one cell type to the next. It is possible that this variation contributes to the range of tumor cell responsiveness that is observed after radiotherapy, especially considering the extensive role for miRNAs in regulating the DDR. In addition, individual miRNAs or miRNA families have been shown to play a multifaceted role in the DDR, regulating multiple members in a single pathway.

CRITICAL ISSUES

In this review, we will discuss the effects of radiation on miRNA expression as well as explore the function of miRNAs in regulating the cellular response to radiation-induced damage. We will discuss the importance of miRNA regulation at each stage of the DDR, including signal transduction, DNA damage sensing, cell cycle checkpoint activation, DNA double-strand break repair, and apoptosis. We will focus on emphasizing the importance of a single miRNA targeting several mediators within a pathway.

FUTURE DIRECTIONS

miRNAs will continue to emerge as critical regulators of the DDR. Understanding the role of miRNAs in the response to IR will provide insights for improving the current standard therapy.

Expression of small glutamine-rich TPR-containing protein A (SGTA) in Non-Hodgkin's Lymphomas promotes tumor proliferation and reverses cell adhesion-mediated drug resistance (CAM-DR)

The expression and biologic function of SGTA in Non-Hodgkin's Lymphomas (NHL) was investigated in this study. Clinically, by immunohistochemistry analysis we detected SGTA expression in both reactive lymphoid tissues and NHL tissues. In addition, we also correlated high expression of SGTA with poor prognosis. Functionally, SGTA expression was positively related with cell proliferation and negative related with cell adhesion. Finally, SGTA knockdown induced adhesion-mediated drug resistance. Our finding supports a role of SGTA in NHL cell proliferation, adhesion and drug resistance, and it may pave the way for a novel therapeutic approach for CAM-DR in NHL.

MicroRNA regulation of the germinal center response

The generation of germinal centers (GCs) is a hallmark feature of the adaptive immune response, resulting in the production of high-affinity antibodies that neutralize pathogens and confer protection upon reinfection. The GC response requires interactions between different immune cell types, and the coordination of complex and dynamic gene expression networks within these cells. Here we provide deeper insights into how microRNAs, small endogenously expressed RNAs, regulate the cellular processes involved in the differentiation and function of T follicular helper cells and germinal center B cells, the two main players of the T cell-dependent humoral immune response.

Inhibition of miR-17 and miR-20a by oridonin triggers apoptosis and reverses chemoresistance by derepressing BIM-S

Cancer cell chemoresistance arises in part through the acquisition of apoptotic resistance. Leukemia cells resistant to chemotherapy-induced apoptosis have been found to be sensitive to oridonin, a natural agent with potent anticancer activity. To investigate its mechanisms of action in reversing chemoresistance, we compared the response of human leukemia cells with oridonin and the antileukemia drugs Ara-C and VP-16. Compared with HL60 cells, K562 and K562/ADR cells displayed resistance to apoptosis stimulated by Ara-C and VP-16 but sensitivity to oridonin. Mechanistic investigations revealed that oridonin upregulated BIM-S by diminishing the expression of miR-17 and miR-20a, leading to mitochondria-dependent apoptosis. In contrast, neither Ara-C nor VP-16 could reduce miR-17 and miR-20a expression or could trigger BIM-S-mediated apoptosis. Notably, silencing miR-17 or miR-20a expression by treatment with microRNA (miRNA; miR) inhibitors or oridonin restored sensitivity of K562 cells to VP-16. Synergistic effects of oridonin and VP-16 were documented in cultured cells as well as mouse tumor xenograft assays. Inhibiting miR-17 or miR-20a also augmented the proapoptotic activity of oridonin. Taken together, our results identify a miRNA-dependent mechanism underlying the anticancer effect of oridonin and provide a rationale for its combination with chemotherapy drugs in addressing chemoresistant leukemia cells.