Molecular Players in Hematologic Tumor Cell Trafficking

The Role of the Microenvironment and Cell Adhesion Molecules in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy whose progression largely depends on the lymph node and bone marrow microenvironment. Indeed, CLL cells actively proliferate in specific regions of these anatomical compartments, known as proliferation centers, while being quiescent in the blood stream. Hence, CLL cell adhesion and migration into these protective niches are critical for CLL pathophysiology. CLL cells are lodged in their microenvironment through a series of molecular interactions that are mediated by cellular adhesion molecules and their counter receptors. The importance of these adhesion molecules in the clinic is demonstrated by the correlation between the expression levels of some of them, in particular CD49d, and the prognostic likelihood. Furthermore, novel therapeutic agents, such as ibrutinib, impair the functions of these adhesion molecules, leading to an egress of CLL cells from the lymph nodes and bone marrow into the circulation together with an inhibition of homing into these survival niches, thereby preventing disease progression. Several adhesion molecules have been shown to participate in CLL adhesion and migration. Their importance also stems from the observation that they are involved in promoting, directly or indirectly, survival signals that sustain CLL proliferation and limit the efficacy of standard and novel chemotherapeutic drugs, a process known as cell adhesion-mediated drug resistance. In this respect, many studies have elucidated the molecular mechanisms underlying cell adhesion-mediated drug resistance, which have highlighted different signaling pathways that may represent potential therapeutic targets. Here, we review the role of the microenvironment and the adhesion molecules that have been shown to be important in CLL and their impact on transendothelial migration and cell-mediated drug resistance. We also discuss how novel therapeutic compounds modulate the function of this important class of molecules.

3D environment controls H3K4 methylation and the mechanical response of the nucleus in acute lymphoblastic leukemia cells

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, and the infiltration of leukemic cells is critical for disease progression and relapse. Nuclear deformability plays a critical role in cancer cell invasion through confined spaces; however, the direct impact of epigenetic changes on the nuclear deformability of leukemic cells remains unclear. Here, we characterized how 3D collagen matrix conditions induced H3K4 methylation in ALL cell lines and clinical samples. We used specific shRNA and chemical inhibitors to target WDR5 (a core subunit involved in H3K4 methylation) and determined that targeting WDR5 reduced the H3K4 methylation induced by the 3D environment and the invasiveness of ALL cells in vitro and in vivo. Intriguingly, targeting WDR5 did not reduce the adhesion or the chemotactic response of leukemia cells, suggesting a different mechanism by which H3K4 methylation might govern ALL cell invasiveness. Finally, we conducted biochemical, and biophysical experiments to determine that 3D environments promoted the alteration of the chromatin, the morphology, and the mechanical behavior of the nucleus in ALL cells. Collectively, our data suggest that 3D environments control an upregulation of H3K4 methylation in ALL cells, and targeting WDR5 might serve as a promising therapeutic target against ALL invasiveness in vivo.

The Nanomechanical Properties of CLL Cells Are Linked to the Actin Cytoskeleton and Are a Potential Target of BTK Inhibitors

Chronic lymphocytic leukemia (CLL) is an incurable disease characterized by an intense trafficking of the leukemic cells between the peripheral blood and lymphoid tissues. It is known that the ability of lymphocytes to recirculate strongly depends on their capability to rapidly rearrange their cytoskeleton and adapt to external cues; however, little is known about the differences occurring between CLL and healthy B cells during these processes. To investigate this point, we applied a single-cell optical (super resolution microscopy) and nanomechanical approaches (atomic force microscopy, real-time deformability cytometry) to both CLL and healthy B lymphocytes and compared their behavior. We demonstrated that CLL cells have a specific actomyosin complex organization and altered mechanical properties in comparison to their healthy counterpart. To evaluate the clinical relevance of our findings, we treated the cells in vitro with the Bruton's tyrosine kinase inhibitors and we found for the first time that the drug restores the CLL cells mechanical properties to a healthy phenotype and activates the actomyosin complex. We further validated these results in vivo on CLL cells isolated from patients undergoing ibrutinib treatment. Our results suggest that CLL cells' mechanical properties are linked to their actin cytoskeleton organization and might be involved in novel mechanisms of drug resistance, thus becoming a new potential therapeutic target aiming at the normalization of the mechanical fingerprints of the leukemic cells.

Extracellular Vesicles in Chronic Lymphocytic Leukemia: Tumor Microenvironment Messengers as a Basis for New Targeted Therapies?

In addition to intrinsic genomic and nongenomic alterations, tumor progression is also dependent on the tumor microenvironment (TME, mainly composed of the extracellular matrix (ECM), secreted factors, and bystander immune and stromal cells). In chronic lymphocytic leukemia (CLL), B cells have a defect in cell death; contact with the TME in secondary lymphoid organs dramatically increases the B cells' survival via the activation of various molecular pathways, including the B cell receptor and CD40 signaling. Conversely, CLL cells increase the permissiveness of the TME by inducing changes in the ECM, secreted factors, and bystander cells. Recently, the extracellular vesicles (EVs) released into the TME have emerged as key arbiters of cross-talk with tumor cells. The EVs' cargo can contain various bioactive substances (including metabolites, proteins, RNA, and DNA); upon delivery to target cells, these substances can induce intracellular signaling and drive tumor progression. Here, we review recent research on the biology of EVs in CLL. EVs have diagnostic/prognostic significance and clearly influence the clinical outcome of CLL; hence, from the perspective of blocking CLL-TME interactions, EVs are therapeutic targets. The identification of novel EV inhibitors might pave the way to the development of novel combination treatments for CLL and the optimization of currently available treatments (including immunotherapy).

Immuno-regulatory malignant B cells contribute to Chronic Lymphocytic Leukemia progression

Chronic Lymphocytic Leukemia (CLL) is a heterogeneous B cell neoplasm ranging from indolent to rapidly progressive disease. Leukemic cell subsets with regulatory properties evade immune clearance; however, the contribution of such subsets during CLL progression is not completely elucidated. Here, we report that CLL B cells crosstalk with their immune counterparts, notably by promoting the regulatory T (Treg) cell compartment and shaping several helper T (Th) subsets. Among various constitutively- and BCR/CD40-mediated factors secreted, tumour subsets co-express two important immunoregulatory cytokines, IL10 and TGFβ1, both associated with a memory B cell phenotype. Neutralizing secreted IL10 or inhibiting the TGFβ signalling pathway demonstrated that these cytokines are mainly involved in Th- and Treg differentiation/maintenance. In line with the regulatory subsets, we also demonstrated that a CLL B cell population expresses FOXP3, a marker of regulatory T cells. Analysis of IL10, TGFβ1 and FOXP3 positive subpopulations frequencies in CLL samples discriminated 2 clusters of untreated CLL patients that were significantly different in Tregs frequency and time-to-treatment. Since this distinction was pertinent to disease progression, the regulatory profiling provides a new rationale for patient stratification and sheds light on immune dysfunction in CLL.

Roadmap for understanding mechanisms on how Epstein-Barr virus triggers multiple sclerosis and for translating these discoveries in clinical trials

Here, we offer a roadmap for what might be studied next in understanding how EBV triggers MS. We focus on two areas: The first area concerns the molecular mechanisms underlying how clonal antibody in the CSF emanates in widespread molecular mimicry to key antigens in the nervous system including GlialCAM, a protein associated with chloride channels. A second and equally high priority in the roadmap concerns various therapeutic approaches that are related to blocking the mechanisms whereby EBV triggers MS. Therapies deserving of attention include clinical trials with antivirals and the development of 'inverse' vaccines based on nucleic acid technologies to control or to eradicate the consequences of EBV infection. High enthusiasm is given to continuation of ongoing clinical trials of cellular adoptive therapy to attack EBV-infected cells. Clinical trials of vaccines to EBV are another area deserving attention. These suggested topics involving research on mechanism, and the design, implementation and performance of well-designed trials are not intended to be an exhaustive list. We have splendid tools available to our community of medical scientists to tackle how EBV triggers MS and then to perhaps change the world with new therapies to potentially eradicate MS, as we have done with nearly complete success for poliomyelitis.

Monoclonal Gammopathies and the Bone Marrow Microenvironment: From Bench to Bedside and Then Back Again

Multiple myeloma (MM) is an incurable hematologic malignancy characterized by a multistep evolutionary pathway, with an initial phase called monoclonal gammopathy of undetermined significance (MGUS), potentially evolving into the symptomatic disease, often preceded by an intermediate phase called "smoldering" MM (sMM). From a biological point of view, genomic alterations (translocations/deletions/mutations) are already present at the MGUS phase, thus rendering their role in disease evolution questionable. On the other hand, we currently know that changes in the bone marrow microenvironment (TME) could play a key role in MM evolution through a progressive shift towards a pro-inflammatory and immunosuppressive shape, which may drive cancer progression as well as clonal plasma cells migration, proliferation, survival, and drug resistance. Along this line, the major advancement in MM patients' survival has been achieved by the introduction of microenvironment-oriented drugs (including immunomodulatory drugs and monoclonal antibodies). In this review, we summarized the role of the different components of the TME in MM evolution from MGUS as well as potential novel therapeutic targets/opportunities.

Extramedullary Multiple Myeloma: A Patient-Focused Review of the Pathogenesis of Bone Marrow Escape

Multiple myeloma (MM) is a neoplastic clonal proliferation of plasma cells, predominantly in the bone marrow. The presentation of MM in extramedullary tissue, particularly the liver, is uncommon with only a few reported cases in literature. We report a rare and unusual presentation of kappa light chain restricted MM with progression of disease to involve the liver. MM was initially diagnosed on bone marrow biopsy, initially treated with carfilzomib, lenalidomide and dexamethasone, later changed to bortezomib, daratumumab and dexamethasone. There was subsequent progression with a new biopsy-proven myelomatous liver lesion. The patient could not receive high-dose chemotherapy due to multiple co-morbidities and extent of disease and eventually succumbed to her disease rapidly. This article emphasizes the poor prognosis of extramedullary involvement in MM and the pathogenic mechanisms by which it develops. Based on a review of the literature of other cases and case series of solitary or diffuse myeloma involvement in the liver, high-dose chemotherapy in combination with proteasome inhibitors and immunomodulators has the best success rate with less relapse and progressive disease in extramedullary myeloma. Our analysis concluded that the gain of CD44, loss of CD56, loss of very late antigen-4 (VLA-4), imbalance of the chemokine receptor-4-chemokine ligand-12 (CXCR4-CXCL12) axis, metastasis-associated lung adenocarcinoma 1 (MALAT1) upregulation, RAS pathway activation as well as 13q and 17p deletions show an increased propensity of malignant plasma cells to leave the bone marrow and hone in extramedullary sites giving rise to more aggressive extramedullary diseases. Targeted therapeutics such as CD44v-directed therapy and reactivation of p53 to wild-type conformation could potentially be evaluated as treatment options in the future to improve outcomes in this aggressive form of MM, especially in patients with advanced disease and limited treatment options.

[The correlation of CD49d expression pattern with molecular genetics and hotspot gene mutants in patients with chronic lymphocytic leukemia]

Objective: To explore the correlation of CD49d expression patterns with molecular genetics and hotspot gene mutants in patients with chronic lymphocytic leukemia. Methods: The expression of CD49d was detected by flow cytometry and grouped into homogeneous, bimodal, negative and positive expression. Panel fluorescence in situ hybridization (FISH) was used for molecular genetics analysis and next-generation sequencing (NGS) was conducted for gene mutation detection. Results: There were 43 patients (23.89% ) with positive CD49d expression, 137 patients (76.11% ) with negative CD49d expression, 96 patients (53.33% ) with homogeneous CD49d expression and 84 patients (46.67% ) with bimodal CD49d expression. Compared with patients in the CD49d negative group, patients in the CD49d positive group had higher Rai stage (P=0.048) and higher proportion of spleen enlargement (P=0.030) . Compared with patients with homogeneous expression of CD49d, patients with bimodal expression of CD49d had a higher proportion of spleen enlargement (P=0.009) . The expression rate of 11q22- in bimodal CD49d(-) group was significantly higher than that in homogeneous CD49d(-) group (24.29% vs 10.45% , P=0.043) . The incidence of +12 in homogeneous CD49d group was higher than that in bimodal CD49d group (16.67% vs 5.95% , P=0.035) . The incidence of +12 in homogeneous CD49d(+) group was higher than that in bimodal CD49d(-) group (17.24% vs 4.29% , P=0.045) . The incidence of +12 in homogeneous CD49d(-) group was higher than that in bimodal CD49d(-) group (16.42% vs 4.29% , P=0.024) . BIRC3 mutation rate in CD49d positive group was higher than that in CD49d negative group (11.63% vs 2.92% , P=0.037) . Conclusion: There were significant correlations between CD49d and 11q22-, +12 and BIRC3 gene mutation. Patients with bimodal CD49d were more correlated with poor prognosis indexes.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Determinants of Drug Resistance in B-Cell Non-Hodgkin Lymphomas: The Case of Lymphoplasmacytic Lymphoma/Waldenström Macroglobulinemia

Lymphoplasmacytic lymphoma (LPL) is a rare subtype of B cell-derived non-Hodgkin lymphoma characterized by the abnormal growth of transformed clonal lymphoplasmacytes and plasma cells. This tumor almost always displays the capability of secreting large amounts of monoclonal immunoglobulins (Ig) of the M class (Waldenström Macroglobulinemia, WM). The clinical manifestations of WM/LPL may range from an asymptomatic condition to a lymphoma-type disease or may be dominated by IgM paraprotein-related symptoms. Despite the substantial progresses achieved over the last years in the therapy of LPL/WM, this lymphoma is still almost invariably incurable and exhibits a propensity towards development of refractoriness to therapy. Patients who have progressive disease are often of difficult clinical management and novel effective treatments are eagerly awaited. In this review, we will describe the essential clinical and pathobiological features of LPL/WM. We will also analyze some key aspects about the current knowledge on the mechanisms of drug resistance in this disease, by concisely focusing on conventional drugs, monoclonal antibodies and novel agents, chiefly Bruton’s Tyrosine Kinase (BTK) inhibitors. The implications of molecular lesions as predictors of response or as a warning for the development of therapy resistance will be highlighted.

Fast H3K9 methylation promoted by CXCL12 contributes to nuclear changes and invasiveness of T-acute lymphoblastic leukemia cells

T-acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that comprises the accumulation of malignant T-cells. Despite current therapies, failure to conventional treatments and relapse are frequent in children with T-ALL. It is known that the chemokine CXCL12 modulates leukemia survival and dissemination; however, our understanding of molecular mechanisms used by T-ALL cells to infiltrate and respond to leukemia cells-microenvironment interactions is still vague. In the present study, we showed that CXCL12 promoted H3K9 methylation in cell lines and primary T-ALL cells within minutes. We thus identified that CXCL12-mediated H3K9 methylation affected the global chromatin configuration and the nuclear mechanics of T-ALL cells. Importantly, we characterized changes in the genomic profile of T-ALL cells associated with rapid CXCL12 stimulation. We showed that blocking CXCR4 and protein kinase C (PKC) impaired the H3K9 methylation induced by CXCL12 in T-ALL cells. Finally, blocking H3K9 methyltransferases reduced the efficiency of T-ALL cells to deform their nuclei, migrate across confined spaces, and home to spleen and bone marrow in vivo models. Together, our data show novel functions for CXL12 as a master regulator of nuclear deformability and epigenetic changes in T-ALL cells, and its potential as a promising pharmacological target against T-ALL dissemination.

Mechanisms of immune effector cell-associated neurotoxicity syndrome after CAR-T treatment

Chimeric antigen receptor T-cell (CAR-T) treatment has revolutionized the landscape of cancer therapy with significant efficacy on hematologic malignancy, especially in relapsed and refractory B cell malignancies. However, unexpected serious toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) still hamper its broad application. Clinical trials using CAR-T cells targeting specific antigens on tumor cell surface have provided valuable information about the characteristics of ICANS. With unclear mechanism of ICANS after CAR-T treatment, unremitting efforts have been devoted to further exploration. Clinical findings from patients with ICANS strongly indicated existence of overactivated peripheral immune response followed by endothelial activation-induced blood-brain barrier (BBB) dysfunction, which triggers subsequent central nervous system (CNS) inflammation and neurotoxicity. Several animal models have been built but failed to fully replicate the whole spectrum of ICANS in human. Hopefully, novel and powerful technologies like single-cell analysis may help decipher the precise cellular response within CNS from a different perspective when ICANS happens. Moreover, multidisciplinary cooperation among the subjects of immunology, hematology, and neurology will facilitate better understanding about the complex immune interaction between the peripheral, protective barriers, and CNS in ICANS. This review elaborates recent findings about ICANS after CAR-T treatment from bed to bench, and discusses the potential cellular and molecular mechanisms that may promote effective management in the future. This article is categorized under: Cancer > Biomedical Engineering Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.

Landscape of 4D Cell Interaction in Hodgkin and Non-Hodgkin Lymphomas

Simple Summary

Little is known about the motility and interaction of primary human lymphoma cells in lymph nodes. The aim of this study therefore was to analyze for the first time if there are differences in motility and interaction with bystander cells between different lymphoma types and normal lymph nodes. We observed systematic differences between B cells and PD1-positive T cells. Furthermore, most cases of Hodgkin lymphomas had fast moving PD1-positive T cells, whereas there was little movement in other lymphoma types. Some lymphomas, particularly Hodgkin lymphomas, presented enhanced cell contacts between neoplastic and reactive cells, suggesting a dependency of lymphoma growth on cellular interaction.

Abstract

Profound knowledge exists about the clinical, morphologic, genomic, and transcriptomic characteristics of most lymphoma entities. However, information is currently lacking on the dynamic behavior of malignant lymphomas. This pilot study aimed to gain insight into the motility of malignant lymphomas and bystander cells in 20 human lymph nodes. Generally, B cells were faster under reactive conditions compared with B cells in malignant lymphomas. In contrast, PD1-positive T cells did not show systematic differences in velocity between reactive and neoplastic conditions in general. However, lymphomas could be divided into two groups: one with fast PD1-positive T cells (e.g., Hodgkin lymphoma and mantle cell lymphoma; means 8.4 and 7.8 µm/min) and another with slower PD1-positive T cells (e.g., mediastinal grey zone lymphoma; mean 3.5 µm/min). Although the number of contacts between lymphoma cells and PD1-positive T cells was similar in different lymphoma types, important differences were observed in the duration of these contacts. Among the lymphomas with fast PD1-positive T cells, contacts were particularly short in mantle cell lymphoma (mean 54 s), whereas nodular lymphocyte-predominant Hodgkin lymphoma presented prolonged contact times (mean 6.1 min). Short contact times in mantle cell lymphoma were associated with the largest spatial displacement of PD1-positive cells (mean 12.3 µm). Although PD1-positive T cells in nodular lymphocyte-predominant Hodgkin lymphoma were fast, they remained in close contact with the lymphoma cells, in line with a dynamic immunological synapse. This pilot study shows for the first time systematic differences in the dynamic behavior of lymphoma and bystander cells between different lymphoma types.

PIM Kinases in Multiple Myeloma

Multiple myeloma (MM) remains an incurable disease and novel therapeutic agents/approaches are urgently needed. The PIM (Proviral insertion in murine malignancies) serine/threonine kinases have 3 isoforms: PIM1, PIM2, and PIM3. PIM kinases are engaged with an expansive scope of biological activities including cell growth, apoptosis, drug resistance, and immune response. An assortment of molecules and pathways that are critical to myeloma tumorigenesis has been recognized as the downstream targets of PIM kinases. The inhibition of PIM kinases has become an emerging scientific interest for the treatment of multiple myeloma and several PIM kinase inhibitors, such as SGI-1776, AZD1208, and PIM447 (formerly LGH447), have been developed and are under different phases of clinical trials. Current research has been focused on the development of a new generation of potent PIM kinase inhibitors with appropriate pharmacological profiles reasonable for human malignancy treatment. Combination therapy of PIM kinase inhibitors with chemotherapeutic appears to create an additive cytotoxic impact in cancer cells. Notwithstanding, the mechanisms by which PIM kinases modulate the immune microenvironment and synergize with the immunomodulatory agents such as lenalidomide have not been deliberately depicted. This review provides a comprehensive overview of the PIM kinase pathways and the current research status of the development of PIM kinase inhibitors for the treatment of MM. Additionally, the combinatorial effects of the PIM kinase inhibitors with other targeted agents and the promising strategies to exploit PIM as a therapeutic target in malignancy are highlighted.

Shared genomic segment analysis in a large high-risk chronic lymphocytic leukemia pedigree implicates CXCR4 in inherited risk

AIM

Chronic lymphocytic leukemia (CLL) has been shown to cluster in families. First-degree relatives of individuals with CLL have an ~8 fold increased risk of developing the malignancy. Strong heritability suggests pedigree studies will have good power to localize pathogenic genes. However, CLL is relatively rare and heterogeneous, complicating ascertainment and analyses. Our goal was to identify CLL risk loci using unique resources available in Utah and methods to address intra-familial heterogeneity.

METHODS

We identified a six-generation high-risk CLL pedigree using the Utah Population Database. This pedigree contains 24 CLL cases connected by a common ancestor. We ascertained and genotyped eight CLL cases using a high-density SNP array, and then performed shared genomic segment (SGS) analysis - a method designed for extended high-risk pedigrees that accounts for heterogeneity.

RESULTS

We identified a genome-wide significant region (P = 1.9 × 10^-7, LOD-equivalent 5.6) at 2q22.1. The 0.9 Mb region was inherited through 26 meioses and shared by seven of the eight genotyped cases. It sits within a ~6.25 Mb locus identified in a previous linkage study of 206 small CLL families. Our narrow region intersects two genes, including CXCR4 which is highly expressed in CLL cells and implicated in maintenance and progression.

CONCLUSION

SGS analysis of an extended high-risk CLL pedigree identified the most significant evidence to-date for a 0.9 Mb CLL disease locus at 2q22.1, harboring CXCR4. This discovery contributes to a growing literature implicating CXCR4 in inherited risk to CLL. Investigation of the segregating haplotype in the pedigree will be valuable for elucidating risk variant(s).

3D Bioprinting Allows the Establishment of Long-Term 3D Culture Model for Chronic Lymphocytic Leukemia Cells

Chronic Lymphocytic Leukemia (CLL) represents the most common leukemia in the western world and remains incurable. Leukemic cells organize and interact in the lymphoid tissues, however what actually occurs in these sites has not been fully elucidated yet. Studying primary CLL cells in vitro is very challenging due to their short survival in culture and also to the fact that traditional two-dimensional in vitro models lack cellular and spatial complexity present in vivo. Based on these considerations, we exploited for the first time three-dimensional (3D) bioprinting to advance in vitro models for CLL. This technology allowed us to print CLL cells (both primary cells and cell lines) mixed with the appropriate, deeply characterized, hydrogel to generate a scaffold containing the cells, thus avoiding the direct cell seeding onto a precast 3D scaffold and paving the way to more complex models. Using this system, we were able to efficiently 3D bioprint leukemic cells and improve their viability in vitro that could be maintained up to 28 days. We monitored over time CLL cells viability, phenotype and gene expression, thus establishing a reproducible long-term 3D culture model for leukemia. Through RNA sequencing (RNAseq) analysis, we observed a consistent difference in gene expression profile between 2D and 3D samples, indicating a different behavior of the cells in the two different culture settings. In particular, we identified pathways upregulated in 3D, at both day 7 and 14, associated with immunoglobulins production, pro-inflammatory molecules expression, activation of cytokines/chemokines and cell-cell adhesion pathways, paralleled by a decreased production of proteins involved in DNA replication and cell division, suggesting a strong adaptation of the cells in the 3D culture. Thanks to this innovative approach, we developed a new tool that may help to better mimic the physiological 3D in vivo settings of leukemic cells as well as of immune cells in broader terms. This will allow for a more reliable study of the molecular and cellular interactions occurring in normal and neoplastic conditions in vivo, and could also be exploited for clinical purposes to test individual responses to different drugs.

Long non-coding RNA LINC01003 suppresses the development of multiple myeloma by targeting miR-33a-5p/PIM1 axis

BACKGROUND

Numerous long non-coding RNAs (lncRNAs) are reported to affect the progression of multiple myeloma (MM). This study is aimed to explore the role and downstream mechanism of lncRNA LINC01003 in MM.

MATERIALS AND METHODS

Xenograft tumor assay was used to assess the function of LINC01003 in MM in vivo. The mRNA expression levels of LINC01003, miR-33a-5p, and PIM1 were determined by quantitative real-time polymerase chain reaction. Cell viability was examined by MTT assay. Relative protein levels of apoptosis-related factors (Bcl-2 and Bax) and proviral integration site of the Moloney leukemia virus kinase 1 (PIM1) were detected via western blot. Adhesion-related proteins were measured by Enzyme-linked immunosorbent assay was used to determine the levels of adhesion-related proteins. Besides, the target relation among LINC01003, miR-33a-5p and PIM1 was tested via dual-luciferase reporter assay.

RESULTS

Low expression of LINC01003 was observed in MM cell lines and peripheral blood samples of MM patients. Both LINC01003 up-regulation and miR-33a-5p down-regulation repressed cell viability and adhesion, and promoted apoptosis of MM cells. Moreover, LINC01003 suppressed the growth of xenograft tumor in mice. We then identified miR-33a-5p as a downstream target of LINC01003, and confirmed that PIM1 was a direct target gene of miR-33a-5p. Both high expression of miR-33a-5p and low expression of PIM1 reversed the suppressive effects of LINC01003 overexpression on cell adhesion and viability, and the promoting effect on apoptosis in MM cells.

CONCLUSION

LINC01003 functioned as a sponge of miR-33a-5p to inhibit the development MM by regulating PIM1 expression.

The Lipoprotein Transport System in the Pathogenesis of Multiple Myeloma: Advances and Challenges

Multiple myeloma (MM) is an incurable neoplastic hematologic disorder characterized by malignant plasma cells, mainly in the bone marrow. MM is associated with multiple factors, such as lipid metabolism, obesity, and age-associated disease development. Although, the precise pathogenetic mechanisms remain unknown, abnormal lipid and lipoprotein levels have been reported in patients with MM. Interestingly, patients with higher APOA1 levels, the major apolipoprotein of high density lipoprotein (HDL), have better overall survival. The limited existing studies regarding serum lipoproteins in MM are inconclusive, and often contradictory. Nevertheless, it appears that deregulation of the lipoprotein transport system may facilitate the development of the disease. Here, we provide a critical review of the literature on the role of lipids and lipoproteins in MM pathophysiology. We also propose novel mechanisms, linking the development and progression of MM to the metabolism of blood lipoproteins. We anticipate that proteomic and lipidomic analyses of serum lipoproteins along with analyses of their functionality may improve our understanding and shed light on novel mechanistic aspects of MM pathophysiology.

Targeting chemokines for acute lymphoblastic leukemia therapy

Acute lymphoblastic leukemia (ALL) is a hematological malignancy characterized by the malignant clonal expansion of lymphoid hematopoietic precursors. It is regulated by various signaling molecules such as cytokines and adhesion molecules in its microenvironment. Chemokines are chemotactic cytokines that regulate migration, positioning and interactions of cells. Many chemokine axes such as CXCL12/CXCR4 and CCL25/CCR9 have been proved to play important roles in leukemia microenvironment and further affect ALL outcomes. In this review, we summarize the chemokines that are involved in ALL progression and elaborate on their roles and mechanisms in leukemia cell proliferation, infiltration, drug resistance and disease relapse. We also discuss the potential of targeting chemokine axes for ALL treatments, since many related inhibitors have shown promising efficacy in preclinical trials, and some of them have entered clinical trials.

Protein kinase PIM2: A simple PIM family kinase with complex functions in cancer metabolism and therapeutics

PIM2 (proviral integration site for Moloney murine leukemia virus 2) kinase plays an important role as an oncogene in multiple cancers, such as leukemia, liver, lung, myeloma, prostate and breast cancers. PIM2 is largely expressed in both leukemia and solid tumors, and it promotes the transcriptional activation of genes involved in cell survival, cell proliferation, and cell-cycle progression. Many tumorigenic signaling molecules have been identified as substrates for PIM2 kinase, and a variety of inhibitors have been developed for its kinase activity, including SMI-4a, SMI-16a, SGI-1776, JP11646 and DHPCC-9. Here, we summarize the signaling pathways involved in PIM2 kinase regulation and PIM2 mechanisms in various neoplastic diseases. We also discuss the current status and future perspectives for the development of PIM2 kinase inhibitors to combat human cancer, and PIM2 will become a therapeutic target in cancers in the future.

The Role of Tumor Microenvironment in Multiple Myeloma Development and Progression

Simple Summary

Multiple Myeloma (MM) is a hematologic malignancy caused by aberrant plasma cell proliferation in the bone marrow (BM) and constitutes the second most common hematological disease after non-Hodgkin lymphoma. The disease progression is drastically regulated by the immunosuppressive tumor microenvironment (TME) generated by soluble factors and different cells that naturally reside in the BM. This microenvironment does not remain unchanged and alterations favor cancer dissemination. Despite therapeutic advances over the past 15 years, MM remains incurable and therefore understanding the elements that control the TME in MM would allow better-targeted therapies to cure this disease. In this review, we discuss the main events and changes that occur in the BM milieu during MM development.

Abstract

Multiple myeloma (MM) is a hematologic cancer characterized by clonal proliferation of plasma cells in the bone marrow (BM). The progression, from the early stages of the disease as monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to MM and occasionally extramedullary disease, is drastically affected by the tumor microenvironment (TME). Soluble factors and direct cell–cell interactions regulate MM plasma cell trafficking and homing to the BM niche. Mesenchymal stromal cells, osteoclasts, osteoblasts, myeloid and lymphoid cells present in the BM create a unique milieu that favors MM plasma cell immune evasion and promotes disease progression. Moreover, TME is implicated in malignant cell protection against anti-tumor therapy. This review describes the main cellular and non-cellular components located in the BM, which condition the immunosuppressive environment and lead the MM establishment and progression.

A narrative review of central nervous system involvement in acute leukemias

Acute leukemias (both myeloid and lymphoblastic) are a group of diseases for which each year more successful therapies are implemented. However, in a subset of cases the overall survival (OS) is still exceptionally low due to the infiltration of leukemic cells in the central nervous system (CNS) and the subsequent formation of brain tumors. The CNS involvement is more common in acute lymphocytic leukemia (ALL), than in adult acute myeloid leukemia (AML), although the rates for the second case might be underestimated. The main reasons for CNS invasion are related to the expression of specific adhesion molecules (VLA-4, ICAM-1, VCAM, L-selectin, PECAM-1, CD18, LFA-1, CD58, CD44, CXCL12) by a subpopulation of leukemic cells, called “sticky cells” which have the ability to interact and adhere to endothelial cells. Moreover, the microenvironment becomes hypoxic and together with secretion of VEGF-A by ALL or AML cells the permeability of vasculature in the bone marrow increases, coupled with the disruption of blood brain barrier. There is a single subpopulation of leukemia cells, called leukemia stem cells (LSCs) that is able to resist in the new microenvironment due to its high adaptability. The LCSs enter into the arachnoid, migrate, and intensively proliferate in cerebrospinal fluid (CSF) and consequently infiltrate perivascular spaces and brain parenchyma. Moreover, the CNS is an immune privileged site that also protects leukemic cells from chemotherapy. CD56/NCAM is the most important surface molecule often overexpressed by leukemic stem cells that offers them the ability to infiltrate in the CNS. Although asymptomatic or with unspecific symptoms, CNS leukemia should be assessed in both AML/ALL patients, through a combination of flow cytometry and cytological analysis of CSF. Intrathecal therapy (ITT) is a preventive measure for CNS involvement in AML and ALL, still much research is needed in finding the appropriate target that would dramatically lower CNS involvement in acute leukemia.

Cadherins, Selectins, and Integrins in CAM-DR in Leukemia

The interaction between leukemia cells and the bone microenvironment is known to provide drug resistance in leukemia cells. This phenomenon, called cell adhesion-mediated drug resistance (CAM-DR), has been demonstrated in many subsets of leukemia including B- and T-acute lymphoblastic leukemia (B- and T-ALL) and acute myeloid leukemia (AML). Cell adhesion molecules (CAMs) are surface molecules that allow cell-cell or cell-extracellular matrix (ECM) adhesion. CAMs not only recognize ligands for binding but also initiate the intracellular signaling pathways that are associated with cell proliferation, survival, and drug resistance upon binding to their ligands. Cadherins, selectins, and integrins are well-known cell adhesion molecules that allow binding to neighboring cells, ECM proteins, and soluble factors. The expression of cadherin, selectin, and integrin correlates with the increased drug resistance of leukemia cells. This paper will review the role of cadherins, selectins, and integrins in CAM-DR and the results of clinical trials targeting these molecules.

Upregulated expression and function of the α4β1 integrin in multiple myeloma cells resistant to bortezomib

The interaction of multiple myeloma (MM) cells with the bone marrow (BM) microenvironment promotes MM cell retention, survival, and resistance to different anti-MM agents, including proteasome inhibitors (PIs) such as bortezomib (BTZ). The α4β1 integrin is a main adhesion receptor mediating MM cell-stroma interactions and MM cell survival, and its expression and function are downregulated by BTZ, leading to inhibition of cell adhesion-mediated drug resistance (CAM-DR) and MM cell apoptosis. Whether decreased α4β1 expression and activity are maintained or recovered upon development of resistance to BTZ represents an important question, as a potential rescue of α4β1 function could boost MM cell survival and disease progression. Using BTZ-resistant MM cells, we found that they not only rescue their α4β1 expression, but its levels were higher than in parental cells. Increased α4β1 expression in resistant cells correlated with enhanced α4β1-mediated cell lodging in the BM, and with disease progression. BTZ-resistant MM cells displayed enhanced NF-κB pathway activation relative to parental counterparts, which contributed to upregulated α4 expression and to α4β1-dependent MM cell adhesion. These data emphasize the upregulation of α4β1 expression and function as a key event during resistance to BTZ in MM, which might indirectly contribute to stabilize this resistance, as stronger MM cell attachment to BM stroma will regain CAM-DR and MM cell growth and survival. Finally, we found a strong correlation between high ITGB1 (integrin β1) expression in MM and poor progression-free survival (PFS) and overall survival (OS) during treatment of MM patients with BTZ and IMIDs, and combination of high ITGB1 levels and presence of the high-risk genetic factor amp1q causes low PFS and OS. These results unravel a novel prognostic value for ITGB1 in myeloma. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Flow Cytometry Analysis Versus E-Cadherin Immunohistochemistry for the Diagnosis of Pure Erythroid Leukemia: A Case Report

Pure erythroid leukemia (PEL) is a rare form of acute myeloid leukemia characterized by the neoplastic proliferation of erythroblasts. PEL is associated with inferior survival outcomes, particularly among patients harboring complex karyotype abnormalities. In this case, we present a 21-year-old Sudanese man who presented to our ER with a two-week history of fever, shortness of breath, fatigue, and exercise intolerance. He had no significant personal medical history or family history of malignancy. A bone marrow biopsy revealed hypercellularity and infiltration by cells with an immature appearance. A flow cytometry (FC) analysis of the bone marrow aspirate revealed that approximately 21% of the total nucleated cells were negative for CD45 and positive for CD71, glycophorin A, and CD36 but negative for myeloperoxidase (MPO), CD33, CD13, CD61, CD41, and other lymphoid and myeloid markers. Consistent with the microscopic analysis, <1% of the total cells were identified as CD34/CD13/CD117-positive myeloblasts. Notably, all stains (CD45, MPO, CD34, CD163, CD61, glycophorin A) were negative except E-cadherin, which positively stained >80% of the cells. Our findings suggested a differential diagnosis that included erythroid leukemia and myelodysplastic syndrome (MDS). The morphological, FC, immunohistochemistry, and cytogenetic findings strongly supported a diagnosis of PEL.

Development of PROTACs to address clinical limitations associated with BTK-targeted kinase inhibitors

Chronic lymphocytic leukemia is a common form of leukemia and is dependent on growth-promoting signaling via the B-cell receptor. The Bruton tyrosine kinase (BTK) is an important mediator of B-cell receptor signaling and the irreversible BTK inhibitor ibrutinib can trigger dramatic clinical responses in treated patients. However, emergence of resistance and toxicity are major limitations which lead to treatment discontinuation. There remains, therefore, a clear need for new therapeutic options. In this review, we discuss recent progress in the development of BTK-targeted proteolysis targeting chimeras (PROTACs) describing how such agents may provide advantages over ibrutinib and highlighting features of PROTACs that are important for the development of effective BTK degrading agents. Overall, PROTACs appear to be an exciting new approach to target BTK. However, development is at a very early stage and considerable progress is required to refine these agents and optimize their drug-like properties before progression to clinical testing.

Genomic Characterization of HIV-Associated Plasmablastic Lymphoma Identifies Pervasive Mutations in the JAK–STAT Pathway

Plasmablastic lymphoma (PBL) is an aggressive B-cell non-Hodgkin lymphoma associated with immunodeficiency in the context of Human Immunodeficiency Virus (HIV) infection or iatrogenic immunosuppression. While a rare disease in general, the incidence is dramatically increased in regions of the world with high HIV prevalence. The molecular pathogenesis of this disease is poorly characterized. Here, we defined the genomic features of PBL in a cohort of 110 patients from South Africa (15 by whole exome sequencing and 95 by deep targeted sequencing). We identified recurrent mutations in genes of the JAK-STAT signaling pathway, including STAT3 (42%), JAK1 (14%) and SOCS1 (10%), leading to its constitutive activation. Moreover, 24% of cases harbored gain-of-function mutations in RAS family members (NRAS and KRAS). Comparative analysis with other B-cell malignancies uncovered PBL-specific somatic mutations and transcriptional programs. We also found recurrent copy number gains encompassing the CD44 gene (37%), which encodes for a cell surface receptor involved in lymphocyte activation and homing, and was found expressed at high levels in all tested cases, independent of genetic alterations. These findings have implications for the understanding of the pathogenesis of this disease and the development of personalized medicine approaches.

Dual Targeting of Stromal Cell Support and Leukemic Cell Growth by a Peptidic PKC Inhibitor Shows Effectiveness against B-ALL

Mesenchymal stem cells (MSC) favour a scenario where leukemic cells survive. The protein kinase C (PKC) is essential to confer MSC support to leukemic cells and may be responsible for the intrinsic leukemic cell growth. Here we have evaluated the capacity of a chimeric peptide (HKPS), directed against classical PKC isoforms, to inhibit leukemic cell growth. HKPS was able to strongly inhibit viability of different leukemic cell lines, while control HK and PS peptides had no effect. Further testing showed that 30% of primary samples from paediatric B-cell acute lymphoblastic leukaemia (B-ALL) were also strongly affected by HKPS. We showed that HKPS disrupted the supportive effect of MSC that promote leukemic cell survival. Interestingly, ICAM-1 and VLA-5 expression increased in MSC during the co-cultures with B-ALL cells, and we found that HKPS inhibited the interaction between MSC and B-ALL cells due to a reduction in the expression of these adhesion molecules. Of note, the susceptibility of B-ALL cells to dexamethasone increased when MSC were treated with HKPS. These results show the relevance of these molecular interactions in the leukemic niche. The use of HKPS may be a new strategy to disrupt intercellular communications, increasing susceptibility to therapy, and at the same time, directly affecting the growth of PKC-dependent leukemic cells.

FtH-Mediated ROS Dysregulation Promotes CXCL12/CXCR4 Axis Activation and EMT-Like Trans-Differentiation in Erythroleukemia K562 Cells

The cell-microenvironment communication is essential for homing of hematopoietic stem cells in stromal niches. Recent evidences support the involvement of epithelial-to-mesenchymal (EMT) process in hematopoietic stem cell homeostasis as well as in leukemia cells invasiveness and migration capability. Here, we demonstrate that the alteration of iron homeostasis and the consequent increase of redox metabolism, mediated by the stable knock down of ferritin heavy chain (FtH), enhances the expression of CXCR4 in K562 erythroleukemia cells, thus promoting CXCL12-mediated motility. Indeed, addition of the CXCR4 receptor antagonist AMD3100 reverts this effect. Upon FtH knock down K562 cells also acquire an “EMT-like” phenotype, characterized by the increase of Snail, Slug and Vimentin with the parallel loss of E-cadherin. By using fibronectin as substrate, the cell adhesion assay further shows a reduction of cell adhesion capability in FtH-silenced K562 cells. Accordingly, confocal microscopy shows that adherent K562 control cells display a variety of protrusions while FtH-silenced K562 cells remain roundish. These phenomena are largely due to the reactive oxygen species (ROS)-mediated up-regulation of HIF-1α/CXCR4 axis which, in turn, promotes the activation of NF-κB and the enhancement of EMT features. These data are confirmed by treatments with either N-acetylcysteine (NAC) or AMD3100 or NF-κB inhibitor IκB-alpha which revert the FtH-silenced K562 invasive phenotype. Overall, our findings demonstrate the existence of a direct relationship among iron metabolism, redox homeostasis and EMT in the hematological malignancies. The effects of FtH dysregulation on CXCR4/CXCL12-mediated K562 cell motility extend the meaning of iron homeostasis in the leukemia cell microenvironment.

Integrated miRNA/mRNA Counter-Expression Analysis Highlights Oxidative Stress-Related Genes CCR7 and FOXO1 as Blood Markers of Coronary Arterial Disease

Our interest in the mechanisms of atherosclerosis progression (ATHp) has led to the recent identification of 13 miRNAs and 1285 mRNAs whose expression was altered during ATHp. Here, we deepen the functional relationship among these 13 miRNAs and genes associated to oxidative stress, a crucial step in the onset and progression of vascular disease. We first compiled a list of genes associated to the response to oxidative stress (Oxstress genes) by performing a reverse Gene Ontology analysis (rGO, from the GO terms to the genes) with the GO terms GO0006979, GO1902882, GO1902883 and GO1902884, which included a total of 417 unique Oxstress genes. Next, we identified 108 putative targets of the 13 miRNAs among these unique Oxstress genes, which were validated by an integrated miRNA/mRNA counter-expression analysis with the 1285 mRNAs that yielded 14 genes, Map2k1, Mapk1, Mapk9, Dapk1, Atp2a2, Gata4, Fos, Egfr, Foxo1, Ccr7, Vkorc1l1, Rnf7, Kcnh3, and Mgat3. GO enrichment analysis and a protein–protein-interaction network analysis (PPI) identified most of the validated Oxstress transcripts as components of signaling pathways, highlighting a role for MAP signaling in ATHp. Lastly, expression of these Oxstress transcripts was measured in PBMCs from patients suffering severe coronary artery disease, a serious consequence of ATHp. This allowed the identification of FOXO1 and CCR7 as blood markers downregulated in CAD. These results are discussed in the context of the interaction of the Oxstress transcripts with the ATHp-associated miRNAs.

Immunoregulatory effects of Lurbinectedin in chronic lymphocytic leukemia

Despite significant therapeutic improvements chronic lymphocytic leukemia (CLL) remains an incurable disease and there is a persistent pursuit of new treatment alternatives. Lurbinectedin, a selective inhibitor of active transcription of protein-coding genes, is currently in phase II/III clinical trials for solid tumors such as small-cell lung cancer (SCLC). In this study, we aimed to evaluate the activity of Lurbinectedin on circulating mononuclear cells from CLL patients and to determine whether Lurbinectedin could affect the cross-talk between B-CLL cells and the tumor microenvironment. We found that Lurbinectedin induced a dose- and time-dependent death in all cell types evaluated, with B cells, monocytes and monocytic myeloid derived suppressor cells (Mo-MDSC) being the most susceptible populations. At sub-apoptotic doses, Lurbinectedin decreased the expression of CCR7 in B-CLL cells and impaired their migration towards CCL19 and CCL21. Furthermore, low concentrations of Lurbinectedin stimulated the synthesis of pro-IL1β in monocytes and nurse-like cells, without inducing the inflammasome activation. Altogether, these results indicate that Lurbinectedin might have antitumor activity in CLL due to its direct action on leukemic cells in combination with its effects on the tumor microenvironment. Our findings encourage further investigation of Lurbinectedin as a potential therapy for CLL.

CD155: A Multi-Functional Molecule in Tumor Progression

CD155 is an adhesion molecule belonging to the Nectin/Nectin-like family often overexpressed on tumor cells and involved in many different processes such as cell adhesion, migration and proliferation. In contrast to these pro-tumorigenic functions, CD155 is also a ligand for the activating receptor DNAM-1 expressed on cytotoxic lymphocytes including Natural Killer (NK) cells and involved in anti-tumor immune response. However, during tumor progression inhibitory receptors for CD155 are up-regulated on the surface of effector cells, contributing to an impairment of their cytotoxic capacity. In this review we will focus on the roles of CD155 as a ligand for the activating receptor DNAM-1 regulating immune surveillance against cancer and as pro-oncogenic molecule favoring tumor proliferation, invasion and immune evasion. A deeper understanding of the multiple roles played by CD155 in cancer development contributes to improving anti-tumor strategies aimed to potentiate immune response against cancer.

Bone Marrow-Derived Mesenchymal Stromal Cells: A Novel Target to Optimize Hematopoietic Stem Cell Transplantation Protocols in Hematological Malignancies and Rare Genetic Disorders

: Mesenchymal stromal cells (MSCs) are crucial elements in the bone marrow (BM) niche where they provide physical support and secrete soluble factors to control and maintain hematopoietic stem progenitor cells (HSPCs). Given their role in the BM niche and HSPC support, MSCs have been employed in the clinical setting to expand ex-vivo HSPCs, as well as to facilitate HSPC engraftment in vivo. Specific alterations in the mesenchymal compartment have been described in hematological malignancies, as well as in rare genetic disorders, diseases that are amenable to allogeneic hematopoietic stem cell transplantation (HSCT), and ex-vivo HSPC-gene therapy (HSC-GT). Dissecting the in vivo function of human MSCs and studying their biological and functional properties in these diseases is a critical requirement to optimize transplantation outcomes. In this review, the role of MSCs in the orchestration of the BM niche will be revised, and alterations in the mesenchymal compartment in specific disorders will be discussed, focusing on the need to correct and restore a proper microenvironment to ameliorate transplantation procedures, and more in general disease outcomes.

CXCL12-CXCL4 heterodimerization prevents CXCL12-driven breast cancer cell migration

Despite improvements in cancer early detection and treatment, metastatic breast cancer remains deadly. Current therapeutic approaches have very limited efficacy in patients with triple negative breast cancer. Among the many mechanisms associated that contribute to cancer progression, signaling through the CXCL12-CXCR4 is an essential step in cancer cell migration. We previously demonstrated the formation of CXCL12-CXCL4 heterodimers (Carlson et al., 2013). Here, we investigated whether CXCL12-CXCL4 heterodimers alter tumor cell migration. CXCL12 alone dose-dependently promoted the MDA-MB 231 cell migration (p < .05), which could be prevented by blocking the CXCR4 receptor. The addition of CXCL4 inhibited the CXCL12-induced cell migration (p < .05). Using NMR spectroscopy, we identified the CXCL4-CXCL12 binding interface. Moreover, we generated a CXCL4-derived peptide homolog of the binding interface that mimicked the activity of native CXCL4 protein. These results confirm the formation of CXCL12-CXCL4 heterodimers and their inhibitory effects on the migration of breast tumors cells. These findings suggest that specific peptides mimicking heterodimerization of CXCL12 might prevent breast cancer cell migration.

LncRNA MALAT1/miR-181a-5p affects the proliferation and adhesion of myeloma cells via regulation of Hippo-YAP signaling pathway

Multiple myeloma (MM) is a plasma cells malignant proliferative disease, especially in aged people. LncRNAs have been considered as important regulators in MM. This research was to study the effect of LncRNA MALAT1 on the proliferation and adhesion of myeloma cells and whether Long non-coding RNAs MALAT1(LncRNA MALAT1) plays its regulative role through Hippo-YAP signaling pathway by targeting miR-181a-5p. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was used to detect the LncRNA MALAT1/miR-181a-5p expression and improve the transfection efficiency. Western blot analysis was used to analyze the expression of proliferation and apoptosis related proteins and Hippo-Yes-associated protein (YAP) signaling pathway related proteins. Cell proliferative ability and cell apoptosis were respectively determined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis. ELISA assay was for the determination of adherence factors. Immunohistochemistry was to detect the expression of proliferation and adhesion related proteins. LncRNA MALAT1 targeting gene was determined by Dual-luciferase reporter assay. LncRNA MALAT1 was increased in MM cells and LncRNA MALAT1 interference could inhibit cell proliferation and promote cell apoptosis with the changes in the related proteins. Also, LncRNA MALAT1 interference could inhibit cell adhesion through Hippo-YAP signaling pathway. MiR-181a-5p was demonstrated to be a target of LncRNA MALAT1 and miR-181a-5p overexpression could also regulate the changes in cellular behavior in accordance with the LncRNA MALAT1 interference. In addition, LncRNA MALAT1 interference could decrease the expression of miR-181a-5p and inhibit the growth of tumor. In conclusion, this study showed that LncRNA MALAT1 interference inhibited the proliferation and adhesion of myeloma cells by the up-regulation of miR-181a-5p through activating the Hippo-YAP signaling pathway.