Interleukin-6 Inhibits Fas-Induced Apoptosis and Stress-Activated Protein Kinase Activation in Multiple Myeloma Cells

Impact of Clonal Heterogeneity in Multiple Myeloma

Multiple myeloma is characterized by a highly heterogeneous disease distribution within the bone marrow-containing skeletal system. In this review, we introduce the molecular mechanisms underlying clonal heterogeneity and the spatio-temporal evolution of myeloma. We discuss the clinical impact of clonal heterogeneity, which is thought to be one of the biggest obstacles to overcome therapy resistance and to achieve cure.

A Novel Necroptosis-Related Signature Can Predict Prognosis and Chemotherapy Sensitivity in Multiple Myeloma

BACKGROUND

Necroptosis is an inflammatory cell death mode, and its association with multiple myeloma (MM) remains unclear.

METHODS

This prospective study first analyzed the association between necroptosis-related signature as well as prognosis and chemotherapy sensitivity in MM using the necroptosis score. Consensus clustering was used to identify necroptosis-related molecular clusters. Least absolute shrinkage and selection operator analysis and multivariate Cox regression analysis were performed to establish the prognostic model of necroptosis-related genes (NRGs).

RESULTS

A high necroptosis score was associated with poor prognosis and abundant immune infiltration. Two molecular clusters (clusters A and B) significantly differed in terms of prognosis and tumor microenvironment. Cluster B had a worse prognosis and higher tumor marker pathway activity than cluster A. The risk score model based on four NRGs can accurately predict the prognosis of patients with MM, which was validated in two validation cohorts. Receiver operating characteristic curve analysis showed that the area under the curves of the risk score in predicting the 1-, 3-, and 5-year survival rates were 0.710, 0.758, and 0.834, respectively. Further, the activity of pathways related to proliferation and genetic regulation in the high-risk group significantly increased. The drug prediction results showed that the low-risk score group was more sensitive to bortezomib, cytarabine, and doxorubicin than the high-risk score group. Meanwhile, the high-risk score group was more sensitive to lenalidomide and vinblastine than the low-risk score group. Finally, the upregulation of model genes CHMP1A, FAS, JAK3, and HSP90AA1 in clinical samples collected from patients with MM was validated via real-time polymerase chain reaction.

CONCLUSION

A systematic analysis of NRGs can help identify potential necroptosis-related mechanisms and provide novel biomarkers for MM prognosis prediction, tumor microenvironment evaluation, and personalized treatment planning.

Autophagy and the Bone Marrow Microenvironment: A Review of Protective Factors in the Development and Maintenance of Multiple Myeloma

The role of the unfolded protein response (UPR) in plasma cells (PC) and their malignant multiple myeloma (MM) counterparts is a well described area of research. The importance of autophagy in these cells, as well as the interplay between autophagy and the UPR system, has also been well studied. In this review, we will discuss the relationship between these two cellular responses and how they can be utilized in MM to account for the high levels of monoclonal immunoglobulin (Ig) protein synthesis that is characteristic of this disease. Interactions between MM cells and the bone marrow (BM) microenvironment and how MM cells utilize the UPR/autophagy pathway for their survival. These interacting pathways form the foundation for the mechanism of action for bortezomib, a proteasome inhibitor used to modify the progression of MM, and the eventual drug resistance that MM cells develop. One important resistance pathway implicated in MM progression is caspase 10 which attenuates autophagy to maintain its prosurvival function and avoid cell death. We lay a groundwork for future research including 3D in vitro models for better disease monitoring and personalized treatment. We also highlight pathways involved in MM cell survival and drug resistance that could be used as new targets for effective treatment.

Long Non-coding RNA 332443 Inhibits Preadipocyte Differentiation by Targeting Runx1 and p38-MAPK and ERK1/2-MAPK Signaling Pathways

Long non-coding RNAs (lncRNAs) have emerged as integral regulators of pathophysiological processes, but their specific roles and mechanisms in adipose tissue development remain largely unknown. Here, through microarray analysis, co-expression, and tissue specific analysis of adipocyte tissues after fasting for 72 h, we found that Lnc-FR332443 expression was dramatically decreased, as well as the expression of Runx1. The UCSC database and Ensembl database indicated that Lnc-FR332443 is the antisense lncRNA of Runx1. Lnc-FR332443 and Runx1 are highly enriched in adipose tissue and downregulated during adipogenic differentiation. Adipose tissue-specific knockdown of Lnc-FR332443 increased fat mass in vivo, and specific knockdown of Lnc-FR332443 in 3T3-L1 preadipocytes promoted adipogenic differentiation. In this process, Runx1 expression was decreased when Lnc-FR332443 was downregulated in adipocytes or 3T3-L1 preadipocytes, and vice versa, when Lnc-FR332443 was upregulated, the expression of Runx1 was increased. However, overexpression of Runx1 decreased the expression of the adipocyte cell marker genes PPARγ, C/EBPα and FABP4 significantly, while not affected the expression of Lnc-FR332443. Mechanistically, Lnc-FR332443 positively regulates Runx1 expression in mouse adipocytes and suppresses adipocyte differentiation by attenuating the phosphorylation of MAPK-p38 and MAPK-ERK1/2 expression. Thus, this study indicated that Lnc-FR332443 inhibits adipogenesis and which might be a drug target for the prevention and treatment of obesity.

ERK signaling mediates resistance to immunomodulatory drugs in the bone marrow microenvironment

Immunomodulatory drugs (IMiDs) have markedly improved patient outcome in multiple myeloma (MM); however, resistance to IMiDs commonly underlies relapse of disease. Here, we identify that tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) knockdown (KD)/knockout (KO) in MM cells mediates IMiD resistance via activation of noncanonical nuclear factor κB (NF-κB) and extracellular signal-regulated kinase (ERK) signaling. Within MM bone marrow (BM) stromal cell supernatants, TNF-α induces proteasomal degradation of TRAF2, noncanonical NF-κB, and downstream ERK signaling in MM cells, whereas interleukin-6 directly triggers ERK activation. RNA sequencing of MM patient samples shows nearly universal ERK pathway activation at relapse on lenalidomide maintenance therapy, confirming its clinical relevance. Combination MEK inhibitor treatment restores IMiD sensitivity of TRAF2 KO cells both in vitro and in vivo. Our studies provide the framework for clinical trials of MEK inhibitors to overcome IMiD resistance in the BM microenvironment and improve patient outcome in MM.

Multi-omics tumor profiling technologies to develop precision medicine in multiple myeloma

Multiple myeloma (MM), the second most common hematologic cancer, is caused by accumulation of aberrant plasma cells in the bone marrow. Its molecular causes are not fully understood and its great heterogeneity among patients complicates therapeutic decision-making. In the past decades, development of new therapies and drugs have significantly improved survival of MM patients. However, resistance to drugs and relapse remain the most common causes of mortality and are the major challenges to overcome. The advent of high throughput omics technologies capable of analyzing big amount of clinical and biological data has changed the way to diagnose and treat MM. Integration of omics data (gene mutations, gene expression, epigenetic information, and protein and metabolite levels) with clinical histories of thousands of patients allows to build scores to stratify the risk at diagnosis and predict the response to treatment, helping clinicians to make better educated decisions for each particular case. There is no doubt that the future of MM treatment relies on personalized therapies based on predictive models built from omics studies. This review summarizes the current treatments and the use of omics technologies in MM, and their importance in the implementation of personalized medicine.

Ovarian Cancer Dissemination-A Cell Biologist's Perspective

Epithelial ovarian cancer (EOC) comprises multiple disease states representing a variety of distinct tumors that, irrespective of tissue of origin, genetic aberrations and pathological features, share common patterns of dissemination to the peritoneal cavity. EOC peritoneal dissemination is a stepwise process that includes the formation of malignant outgrowths that detach and establish widespread peritoneal metastases through adhesion to serosal membranes. The cell biology associated with outgrowth formation, detachment, and de novo adhesion is at the nexus of diverse genetic backgrounds that characterize the disease. Development of treatment for metastatic disease will require detailed characterization of cellular processes involved in each step of EOC peritoneal dissemination. This article offers a review of the literature that relates to the current stage of knowledge about distinct steps of EOC peritoneal dissemination, with emphasis on the cell biology aspects of the process.

Postoperative Serum C-Reactive Protein Level Predicts Long-term Outcomes in Stage I Gastric Cancer

BACKGROUND

The aim of this study was to investigate the prognostic impact of postoperative systemic inflammation in patients with stage I gastric cancer.

METHODS

This study reviewed the medical records of 470 patients with stage I gastric cancer who underwent gastrectomy. The postoperative serum C-reactive protein (CRP) level on postoperative days (PODs) 1 and 3 and its peak value were evaluated as prognostic factors. A receiver operating characteristics curve analysis was performed to determine their cut-off values.

RESULTS

The CRP level on POD 3 (P = 0.001) and the peak CRP level (P = 0.007) were significantly associated with the overall survival rate. In the multivariate analysis, the CRP level on POD 3 (P = 0.002) and the peak CRP level (P = 0.008) were identified as independent predictors of the overall survival. The high CRP on POD3 group had significantly higher mortality rate from relapse of gastric cancer (P = 0.001) and infectious disease (P = 0.003) than the low CRP on POD 3 group. The CRP level on POD 3 was significantly associated with the patient sex, surgical procedure, duration of the operation, amount of blood loss, postoperative infectious complication, and peak CRP level.

CONCLUSIONS

The serum CRP level during the early postoperative period predicts the long-term outcomes in stage I gastric cancer. The present study suggests a significant influence of postoperative systemic inflammation on the survival of patients with stage I gastric cancer.

Effect of levamisole on expression of CD138 and interleukin-6 in human multiple myeloma cell lines

INTRODUCTION

Multiple myeloma (MM) is a B-cell malignancy accounting for 0.8% of all cancer deaths globally. This malignancy is characterized by lytic bone disease renal insufficiency, anemia, hypercalcemia, and immunodeficiency. The myeloma cells have enhanced expression of CD138. CD138 is a transmembrane heparin sulfate glycoprotein expressed on different types of adherent and nonadherent cells.CD138 is used as a standard marker for identification of tumor cells.

AIMS AND OBJECTIVES

Despite introduction of many therapeutic agents, the management of multiple myeloma (MM) remains a challenge and search for new therapeutic agents is in progress. In this study, we attempted to evaluate the effect of an alkaline phosphatase inhibitor, levamisole on expression of CD138, and level of interleukin-6 (IL-6) in human MM cell lines RPMI 8226 and U266 B1.

MATERIAL AND METHODS

U266B1 and RPMI 8226 cell lines were obtained from the National Centre for Cell Sciences, Pune. Alkaline phosphatase assay, Interleukin-6 assay and CD138 expression on myeloma cells by flow cytometry were investigated when the cells were exposed to Levamisole.

RESULTS

Levamisole-mediated growth inhibition of myeloma cells in vitro is associated with a loss of CD138 and increased IL-6 secretion. The increased secretion of IL-6 by myeloma cells could be an attempt to protect themselves from apoptosis.

CONCLUSION

Levamisole inhibited CD138 expression and affected the levels of IL-6 in a dose-dependent manner. The results of the present study add new dimension to levamisole's mode of action as inhibitor of CD138 and IL-6 and as an antiapoptotic agent.

Type I insulin-like growth factor receptor signaling in hematological malignancies

The insulin-like growth factor (IGF) signaling system plays key roles in the establishment and progression of different types of cancer. In agreement with this idea, substantial evidence has shown that the type I IGF receptor (IGF-IR) and its primary ligand IGF-I are important for maintaining the survival of malignant cells of hematopoietic origin. In this review, we discuss current understanding of the role of IGF-IR signaling in cancer with a focus on the hematological neoplasms. We also address the emergence of IGF-IR as a potential therapeutic target for the treatment of different types of cancer including plasma cell myeloma, leukemia, and lymphoma.

Microenvironment drug resistance in multiple myeloma: emerging new players

Multiple myeloma (MM) drug resistance (DR) is a multistep transformation process based on a powerful interplay between bone marrow stromal cells and MM cells that allows the latter to escape anti-myeloma therapies. Here we present an overview of the role of the bone marrow microenvironment in both soluble factors-mediated drug resistance (SFM-DR) and cell adhesion-mediated drug resistance (CAM-DR), focusing on the role of new players, namely miRNAs, exosomes and cancer-associated fibroblasts.

Bone marrow stroma protects myeloma cells from cytotoxic damage via induction of the oncoprotein MUC1

Multiple myeloma (MM) is a lethal haematological malignancy that arises in the context of a tumour microenvironment that promotes resistance to apoptosis and immune escape. In the present study, we demonstrate that co-culture of MM cells with stromal cells results in increased resistance to cytotoxic and biological agents as manifested by decreased rates of cell death following exposure to alkylating agents and the proteosome inhibitor, bortezomib. To identify the mechanism of increased resistance, we examined the effect of the co-culture of MM cells with stroma cells, on expression of the MUC1 oncogene, known to confer tumour cells with resistance to apoptosis and necrosis. Co-culture of stroma with MM cells resulted in increased MUC1 expression by tumour cells. The effect of stromal cell co-culture on MUC1 expression was not dependent on cell contact and was therefore thought to be due to soluble factors secreted by the stromal cells into the microenvironment. We demonstrated that MUC1 expression was mediated by interleukin-6 and subsequent up-regulation of the JAK-STAT pathway. Interestingly, the effect of stromal cell co-culture on tumour resistance was partially reversed by silencing of MUC1 in MM cells, consistent with the potential role of MUC1 in mediating resistance to cytotoxic-based therapies.

Siltuximab (CNTO 328) with lenalidomide, bortezomib and dexamethasone in newly-diagnosed, previously untreated multiple myeloma: an open-label phase I trial

The safety and efficacy of siltuximab (CNTO 328) was tested in combination with lenalidomide, bortezomib and dexamethasone (RVD) in patients with newly-diagnosed, previously untreated symptomatic multiple myeloma. Fourteen patients were enrolled in the study, eleven of whom qualified to receive therapy. A majority of patients (81.8%) completed the minimal number or more of the four required cycles, while two patients completed only three cycles. The maximum tolerated dose (MTD) of siltuximab with RVD was dose level −1 (siltuximab: 8.3 mg/kg; bortezomib: 1.3 mg/m²; lenalidomide: 25 mg; dexamethasone: 20 mg). Serious adverse events were grade 3 pneumonia and grade 4 thrombocytopenia, and no deaths occurred during the study or with follow-up (median follow-up 28.1 months). An overall response rate, after 3–4 cycles of therapy, of 90.9% (95% confidence interval (CI): 58.7%, 99.8%) (9.1% complete response (95% CI: 0.2%, 41.3%), 45.5% very good partial response (95% CI: 16.7%, 76.6%) and 36.4% partial response (95% CI: 10.9%, 69.2%)) was seen. Two patients withdrew consent, and nine patients (81.8%) opted for autologous stem cell transplantation.

Mechanisms of Drug Resistance in Relapse and Refractory Multiple Myeloma

Multiple myeloma (MM) is a hematological malignancy that remains incurable because most patients eventually relapse or become refractory to current treatments. Although the treatments have improved, the major problem in MM is resistance to therapy. Clonal evolution of MM cells and bone marrow microenvironment changes contribute to drug resistance. Some mechanisms affect both MM cells and microenvironment, including the up- and downregulation of microRNAs and programmed death factor 1 (PD-1)/PD-L1 interaction. Here, we review the pathogenesis of MM cells and bone marrow microenvironment and highlight possible drug resistance mechanisms. We also review a potential molecular targeting treatment and immunotherapy for patients with refractory or relapse MM.

IL6 secreted by Ewing sarcoma tumor microenvironment confers anti-apoptotic and cell-disseminating paracrine responses in Ewing sarcoma cells

Background

The prognosis of patients with Ewing sarcoma (ES) has improved over the course of the last decades. However, those patients suffering from metastatic and recurrent ES still have only poor chances of survival and require new therapeutic approaches. Interleukin-6 (IL6) is a pleiotropic cytokine expressed by immune cells and a great variety of cancer cells. It induces inflammatory responses, enhances proliferation and inhibits apoptosis in cancer cells, thereby promoting chemoresistance.

Methods

We investigated expression of IL6, its receptors and the IL6 signal transduction pathway in ES tumor samples and cell lines applying reverse transcriptase PCR, immunoblot and immunohistochemistry. The impact of IL6 on cell viability and apoptosis in ES cell lines was analyzed by MTT and propidium iodide staining, migration assessed by chorioallantoic membrane (CAM) assay.

Results

Immunohistochemistry proved IL6 expression in the stroma of ES tumor samples. IL6 receptor subunits IL6R and IL6ST were expressed on the surface of ES cells. Treatment of ES cells with rhIL6 resulted in phosphorylation of STAT3. rhIL6 protected ES cells from serum starvation-induced apoptosis and promoted migration. IL6 blood serum levels were elevated in a subgroup of ES patients with poor prognosis.

Conclusions

These data suggest that IL6 contributes to ES tumor progression by increasing resistance to apoptosis in conditions of cellular stress, such as serum starvation, and by promotion of metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1564-7) contains supplementary material, which is available to authorized users.

Drug resistance in multiple myeloma: latest findings and new concepts on molecular mechanisms

In the era of new and mostly effective therapeutic protocols, multiple myeloma still tends to be a hard-to-treat hematologic cancer. This hallmark of the disease is in fact a sequel to drug resistant phenotypes persisting initially or emerging in the course of treatment. Furthermore, the heterogeneous nature of multiple myeloma makes treating patients with the same drug challenging because finding a drugable oncogenic process common to all patients is not yet feasible, while our current knowledge of genetic/epigenetic basis of multiple myeloma pathogenesis is outstanding. Nonetheless, bone marrow microenvironment components are well known as playing critical roles in myeloma tumor cell survival and environment-mediated drug resistance happening most possibly in all myeloma patients. Generally speaking, however; real mechanisms underlying drug resistance in multiple myeloma are not completely understood. The present review will discuss the latest findings and concepts in this regard. It reviews the association of important chromosomal translocations, oncogenes (e.g. TP53) mutations and deranged signaling pathways (e.g. NFκB) with drug response in clinical and experimental investigations. It will also highlight how bone marrow microenvironment signals (Wnt, Notch) and myeloma cancer stem cells could contribute to drug resistance in multiple myeloma.

Preclinical validation of interleukin 6 as a therapeutic target in multiple myeloma

Studies on the biologic and molecular genetic underpinnings of multiple myeloma (MM) have identified the pleiotropic, pro-inflammatory cytokine, interleukin-6 (IL-6), as a factor crucial to the growth, proliferation and survival of myeloma cells. IL-6 is also a potent stimulator of osteoclastogenesis and a sculptor of the tumor microenvironment in the bone marrow of patients with myeloma. This knowledge has engendered considerable interest in targeting IL-6 for therapeutic purposes, using a variety of antibody- and small-molecule-based therapies. However, despite the early recognition of the importance of IL-6 for myeloma and the steady progress in our knowledge of IL-6 in normal and malignant development of plasma cells, additional efforts will be required to translate the promise of IL-6 as a target for new myeloma therapies into significant clinical benefits for patients with myeloma. This review summarizes published research on the role of IL-6 in myeloma development and describes ongoing efforts by the University of Iowa Myeloma Multidisciplinary Oncology Group to develop new approaches to the design and testing of IL-6-targeted therapies and preventions of MM.

Zoledronic acid exerts its antitumor effect in multiple myeloma interfering with the bone marrow microenvironment

Multiple myeloma (MM) is a B-cell malignancy characterized by an excess of monotypic plasma cells which localize almost exclusively in the bone marrow provoking bone destruction via the activation of the osteoclasts. The bone marrow microenvironment, mainly through stromal cells, is strictly involved in the evolution of the disease supporting MM cell growth and survival [1]. MM plasma cells reside in the bone marrow by binding to adhesion molecule of extracellular matrix (ECM) and stromal cells. The activation of some signaling pathways within the stromal cells increases the production of several cytokines which in turn favors the myeloma cell proliferation and survival [2-6], and enhance the drug resistance by anti-apoptotic mechanisms [1,7-9]. Novel therapeutic agents target not only the myeloma cells but also the interaction between MM cells and the bone marrow microenvironment [8]. Bisphosphonates (Bps) interfere as well with bone microenvironment inhibiting the survival of stromal cells and hampering the contact between plasma and stromal cells. In this review we will revise preclinical evidences, and the potential mechanisms of the antitumor activity of zoledronic acid.

Lenalidomide in multiple myeloma: Current status and future potential

The clinical development of lenalidomide (Revlimid™), then pomalidomide (Actimid™) as members of immunomodulatory drugs (IMiDs) for the treatment of multiple myeloma (MM), exemplifies how insight into disease biology can lead to design of effective therapeutic agents. Increased experience and understanding of IMiD's diverse biological effects has lead to rational design of lenalidomide-based treatment-regimens over recent years. However, much about lenalidomide is yet to be understood and fully exploited. Here, we review what is known of lenalidomide's biological effects, clinical certainties and uncertainties in the treatment of MM, and explore its future potential with other synergistic therapeutic agents.

Can we change the disease biology of multiple myeloma?

Despite improvements in disease management, multiple myeloma (MM) remains incurable. Conventional treatment methods are unsatisfactory, leading to a pattern of regression and remission, and ultimately failure. This pattern suggests that one of the possible strategies for improving outcomes is continuous therapy to maintain suppression of the surviving tumor cells. Optimal management of MM requires potent agents and modalities with direct tumoricidal activity, which can also provide continuous suppression of the residual tumor to prevent disease relapse. Immunomodulatory agents exert immunomodulatory and tumoricidal effects, and cause disruption of stromal cell support from the bone marrow microenvironment. Therefore continuous therapy with immunomodulatory agents may be able to provide both tumor reduction and tumor suppression, enabling physicians to consider the possibility of incorporating continuous therapy into the treatment paradigm of patients with MM.

Bone marrow microenvironment in multiple myeloma progression

Substantial advances have been made in understanding the biology of multiple myeloma (MM) through the study of the bone marrow (BM) microenvironment. Indeed, the BM niche appears to play an important role in differentiation, migration, proliferation, survival, and drug resistance of the malignant plasma cells. The BM niche is composed of a cellular compartment (stromal cells, osteoblasts, osteoclasts, endothelial cells, and immune cells) and a noncellular compartment including the extracellular matrix (ECM) and the liquid milieu (cytokines, growth factors, and chemokines). In this paper we discuss how the interaction between the malignant plasma cell and the BM microenvironment allowed myeloma progression through cell homing and the new concept of premetastatic niche.

STAT3 activation by IL-6 from mesenchymal stem cells promotes the proliferation and metastasis of osteosarcoma

We previously demonstrated that human mesenchymal stem cells (MSCs) promote the growth of osteosarcoma in the bone microenvironment. The aim of the present study was to further determine the effect of IL-6/STAT3 signaling on the progression of osteosarcoma. First, conditioned medium from MSCs was used to stimulate the growth of osteosarcoma cells (Saos-2) in vitro. We found that STAT3 was activated and that the activation could be blocked by an IL-6-neutralizing antibody. The inhibition of STAT3 in Saos-2 cells by siRNA or AG490 decreased cell proliferation, migration and invasion, down-regulated the mRNA expression of Cyclin D, Bcl-xL and Survivin and enhanced the apoptotic response. Furthermore, a nude mouse osteosarcoma model was established by injecting luciferase-labeled Saos-2 cells into the tibia, and the effect of STAT3 on tumor growth was determined by treating the mice with AG490. In vivo bioluminescence images showed that tumor growth was dramatically reduced in the AG490 group. In addition, STAT3 inhibition decreased the lung metastasis rate and prolonged the survival of these mice. After treatment with AG490, the protein levels of IL-6, p-STAT3 and PCNA were decreased, and the level of apoptosis in the tumor was increased. Altogether, these data indicate that MSCs in the bone microenvironment might promote the progression of osteosarcoma and protect tumor cells from drug-induced apoptosis through IL-6/STAT3 signaling.

Thrombospondin-1 inhibits osteogenic differentiation of human mesenchymal stem cells through latent TGF-β activation

Transforming growth factor-β (TGF-β) is a critical regulator of bone development and remodeling. TGF-β must be activated from its latent form in order to signal. Thrombospondin-1 (TSP1) is a major regulator of latent TGF-β activation and TSP1 control of TGF-β activation is critical for regulation of TGF-β activity in multiple diseases. Bone marrow-derived mesenchymal stem cells (MSCs) have osteogenic potential and they participate in bone remodeling in injury and in response to tumor metastasis. Since both TSP1 and TGF-β inhibit osteoblast differentiation, we asked whether TSP1 blocks osteoblast differentiation of MSCs through its ability to stimulate TGF-β activation. TSP1 added to human bone marrow-derived MSCs under growth conditions increases active TGF-β. Cultured MSCs express TSP1 and both TSP1 expression and TGF-β activity decrease during osteoblast differentiation. TSP1 and active TGF-β block osteoblast differentiation of MSCs grown in osteogenic media as measured by decreased Runx2 and alkaline phosphatase expression. The inhibitory effect of TSP1 on osteoblast differentiation is due to its ability to activate latent TGF-β, since a peptide which blocks TSP1 TGF-β activation reduced TGF-β activity and restored osteoblast differentiation as measured by increased Runx2 and alkaline phosphatase expression. Anti-TGF-β neutralizing antibody also increased alkaline phosphatase expression in the presence of TSP1. These studies show that TSP1 regulated TGF-β activity is a critical determinant of osteoblast differentiation.

B-cell stimulatory cytokines and markers of immune activation are elevated several years prior to the diagnosis of systemic AIDS-associated non-Hodgkin B-cell lymphoma

BACKGROUND

The risk of developing non-Hodgkin lymphoma (NHL) is greatly increased in HIV infection. The aim of this study was to determine whether elevated serum levels of molecules associated with B-cell activation precede the diagnosis of AIDS-associated NHL (AIDS-NHL).

METHODS

Serum levels of B-cell activation-associated molecules, interleukin (IL)6, IL10, soluble CD23 (sCD23), sCD27, sCD30, C-reactive protein (CRP), and immunoglobulin E were determined in 179 NHL cases and HIV+ controls in the Multicenter AIDS Cohort Study, collected at up to 3 time points per subject, 0 to 5 years prior to AIDS-NHL diagnosis.

RESULTS

Serum IL6, IL10, CRP, sCD23, sCD27, and sCD30 levels were all significantly elevated in the AIDS-NHL group, when compared with HIV+ controls or with AIDS controls, after adjusting for CD4 T-cell number. Elevated serum levels of B-cell activation-associated molecules were seen to be associated with the development of systemic [non-CNS (central nervous system)] NHL, but not with the development of primary CNS lymphoma.

CONCLUSIONS

Levels of certain B-cell stimulatory cytokines and molecules associated with immune activation are elevated for several years preceding the diagnosis of systemic AIDS-NHL. This observation is consistent with the hypothesis that chronic B-cell activation contributes to the development of these hematologic malignancies.

IMPACT

Marked differences in serum levels of several molecules are seen for several years prediagnosis in those who eventually develop AIDS-NHL. Some of these molecules may serve as candidate biomarkers and provide valuable information to better define the etiology of NHL.

Multiple myeloma: biology of the disease

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by the aberrant expansion of plasma cells within the bone marrow, as well as at extramedullary sites. Decades of scientific research are now beginning to unravel the intricate biology that underlies the pathophysiology of MM. In particular, the roles of cellular differentiation, molecular pathogenesis, and oncogenes involved in the natural history of MM are becoming clearer. This has enabled the identification of specific cytokines, adhesion molecules, and stromal cells that affect MM cell development, disease progression, and treatment responses. This review describes our current understanding regarding the biology of MM, and how this has led to a robust pipeline of novel therapeutic agents with the potential to overcome resistance to existing MM therapies and, therefore, further improve outcomes in patients with MM.

Antimyeloma activity of a multitargeted kinase inhibitor, AT9283, via potent Aurora kinase and STAT3 inhibition either alone or in combination with lenalidomide

PURPOSE

Aurora kinases, whose expression is linked to genetic instability and cellular proliferation, are being investigated as novel therapeutic targets in multiple myeloma (MM). In this study, we investigated the preclinical activity of a small-molecule multitargeted kinase inhibitor, AT9283, with potent activity against Aurora kinase A, Aurora kinase B, and Janus kinase 2/3.

EXPERIMENTAL DESIGN

We evaluated the in vitro antimyeloma activity of AT9283 alone and in combination with lenalidomide and the in vivo efficacy by using a xenograft mouse model of human MM.

RESULTS

Our data showed that AT9283 induced cell-growth inhibition and apoptosis in MM. Studying the apoptosis mechanism of AT9283 in MM, we observed features consistent with both Aurora kinase A and Aurora kinase B inhibition, such as increase of cells with polyploid DNA content, decrease in phospho-histone H3, and decrease in phospho-Aurora A. Importantly, AT9283 also inhibited STAT3 tyrosine phosphorylation in MM cells. Genetic depletion of STAT3, Aurora kinase A, or Aurora kinase B showed growth inhibition of MM cells, suggesting a role of AT9283-induced inhibition of these molecules in the underlying mechanism of MM cell death. In vivo studies showed decreased MM cell growth and prolonged survival in AT9283-treated mice compared with controls. Importantly, combination studies of AT9283 with lenalidomide showed significant synergistic cytotoxicity in MM cells, even in the presence of bone marrow stromal cells. Enhanced cytotoxicity was associated with increased inhibition of phosphorylated STAT3 and phosphorylated extracellular signal-regulated kinase.

CONCLUSIONS

Demonstration of in vitro and in vivo anti-MM activity of AT9283 provides the rationale for the clinical evaluation of AT9283 as monotherapy and in combination therapy for treating patients with MM.

Proteomics: addressing the challenges of multiple myeloma

Multiple myeloma (MM) is a malignancy of terminally differentiated B-lymphocytes that accounts for ~13% of all hematologic cancers. Despite a wealth of knowledge describing the molecular biology of MM as well as significant advances in therapeutics, this disease remains incurable. Since proteins govern the cellular structure and biological function, a wide selection of proteomic approaches holds great promise for increasing our understanding of this disease, such as by investigating the dynamic nature of protein expression, cellular and subcellular distribution, post-translational modifications, and interactions at both the cellular and subcellular levels. The aims of this review are to introduce the available and emerging proteomic technologies that have potential applications in the study of MM and to highlight the current status of proteomic studies of MM. To date, although there have been a limited number of proteomic studies in MM, those performed have provided valuable information with regard to MM diagnosis and therapy. The potential future application of proteomic technologies is expected to provide new avenues in MM diagnostics, individualized therapy design and therapy response surveillance for the clinician.

AT7519, A novel small molecule multi-cyclin-dependent kinase inhibitor, induces apoptosis in multiple myeloma via GSK-3beta activation and RNA polymerase II inhibition

Dysregulated cell cycling is a universal hallmark of cancer and is often mediated by abnormal activation of cyclin-dependent kinases (CDKs) and their cyclin partners. Overexpression of individual complexes are reported in multiple myeloma (MM), making them attractive therapeutic targets. In this study, we investigate the preclinical activity of a novel small-molecule multi-CDK inhibitor, AT7519, in MM. We show the anti-MM activity of AT7519 displaying potent cytotoxicity and apoptosis; associated with in vivo tumor growth inhibition and prolonged survival. At the molecular level, AT7519 inhibited RNA polymerase II (RNA pol II) phosphorylation, a CDK9, 7 substrate, associated with decreased RNA synthesis confirmed by [(3)H] Uridine incorporation. In addition, AT7519 inhibited glycogen synthase kinase 3beta (GSK-3beta) phosphorylation; conversely pretreatment with a selective GSK-3 inhibitor and shRNA GSK-3beta knockdown restored MM survival, suggesting the involvement of GSK-3beta in AT7519-induced apoptosis. GSK-3beta activation was independent of RNA pol II dephosphorylation confirmed by alpha-amanitin, a specific RNA pol II inihibitor, showing potent inhibition of RNA pol II phosphorylation without corresponding effects on GSK-3beta phosphorylation. These results offer new insights into the crucial, yet controversial role of GSK-3beta in MM and show significant anti-MM activity of AT7519, providing the rationale for its clinical evaluation in MM.

Autocrine production of interleukin-6 confers cisplatin and paclitaxel resistance in ovarian cancer cells

It has been shown that IL-6 is elevated in the serum and ascites of ovarian cancer patients, and increased IL-6 concentration correlates with poor prognosis and chemoresistance. However, the role of IL-6 expression in the acquisition of the chemoresistance phenotype and the underlining mechanisms of drug resistance in ovarian cancer cells remain unclear. Here we demonstrate that both exogenous (a relatively short period of treatment with recombination IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) induce cisplatin and paclitaxel resistance in non-IL-6-expressing A2780 cells, while deleting of endogenous IL-6 expression in IL-6-overexpressing SKOV3 cells (by transfecting with plasmid encoding for antisense IL-6) promotes the sensitivity of these cells to anticancer drugs. IL-6-mediated resistance of ovarian cancer cells exhibits decreased proteolytic activation of caspase-3. Meanwhile, the further study demonstrates that the chemoresistance caused by IL-6 is associated with increased expression of both multidrug resistance-related genes (MDR1 and GSTpi) and apoptosis inhibitory proteins (Bcl-2, Bcl-xL and XIAP), as well as activation of Ras/MEK/ERK and PI3K/Akt signaling. Therefore, modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant ovarian cancer.

Phosphoproteomic analysis of primary human multiple myeloma cells

Multiple myeloma (MM) is a malignant disorder of differentiated B cells. Clonal expansion of the tumor results in the excessive production of monoclonal immunoglobulin (Ig) which is a diagnostic feature of this disease. Previous investigations have demonstrated the alteration of the ERK, jun kinase, STAT, and AKT kinase signaling cascades in MM cells, suggesting that deregulated phosphorylation may contribute to MM pathogenesis. However, systematic analysis of the phosphoproteome in MM cells has not been reported. Here, we described a large-scale phosphorylation analysis of primary MM cells. Using a separation strategy involving immunomagnetic bead-positive selection of MM cells, preparative SDS-PAGE for prefractionation, in-gel digestion with trypsin, and titanium dioxide enrichment of phosphopeptides, followed by LC-MS/MS analysis employing a hybrid LTQ-Orbitrap mass spectrometer, we were able to catalog a substantial portion of the phosphoproteins present in primary MM cells. This analysis led to the identification of 530 phosphorylation sites from 325 unique phosphopeptides corresponding to 260 proteins at false positive rate (FPR) of 1.3%. This dataset provides an important resource for future studies on phosphorylation and carcinogenesis analysis of multiple myeloma.

A high-affinity fully human anti-IL-6 mAb, 1339, for the treatment of multiple myeloma

PURPOSE

We investigated the in vitro and in vivo anti-multiple myeloma activity of monoclonal antibody (mAb) 1339, a high-affinity fully humanized anti-interleukin 6 mAb (immunoglobulin G1), alone and in combination with conventional and novel anti-multiple myeloma agents, as well as its effect on bone turnover.

EXPERIMENTAL DESIGN

We examined the growth inhibitory effect of 1339 against multiple myeloma cell lines in the absence and in the presence of bone marrow stromal cells, alone or in combination with dexamethasone, bortezomib, perifosine, and Revlimid. Using the severe combined immunodeficient (SCID)-hu murine model of multiple myeloma, we also examined the effect of 1339 on multiple myeloma cell growth and multiple myeloma bone disease.

RESULTS

mAb 1339 significantly inhibited growth of multiple myeloma cell in the presence of bone marrow stromal cell in vitro, associated with inhibition of phosphorylation of signal transducer and activator of transcription 3, extracellular signal-regulated kinase 1/2, and Akt. In addition, mAb 1339 enhanced cytotoxicity induced by dexamethasone, as well as bortezomib, lenalidomide, and perifosine, in a synergistic fashion. Importantly mAb 1339 significantly enhanced growth inhibitory effects of dexamethasone in vivo in SCID-hu mouse model of multiple myeloma. mAb 1339 treatment also resulted in inhibition of osteoclastogenesis in vitro and bone remodeling in SCID-hu model.

CONCLUSIONS

Our data confirm in vitro and in vivo anti-multiple myeloma activity of, as well as inhibition of bone turnover by, fully humanized mAb 1339, as a single agent and in combination with conventional and novel agents, providing a rationale for its clinical evaluation in multiple myeloma.

Mechanism of action of immunomodulatory drugs (IMiDS) in multiple myeloma

Immunomodulatory drugs (IMiDs) are thalidomide analogues, which possess pleiotropic anti-myeloma properties including immune-modulation, anti-angiogenic, anti-inflammatory and anti-proliferative effects. Their development was facilitated by an improved understanding in myeloma (MM) biology and initiated a profound shift in the therapeutic approach towards MM. Despite the diverse effects of IMiDs in vitro, the relative contribution of each effect towards their ultimate anti-MM activity is still unclear. Based on in vitro data, it appears that anti-proliferative effects and downregulation of crucial cytokines are their most important anti-MM attributes. Although the co-stimulatory effects on T and NK cells have been heralded as a unique and important property of IMiDs towards enhancing anti-MM immune activity, these in vitro effects have yet to be firmly corroborated in vivo. Much is yet to be elucidated regarding the complex interplay of immunomodulatory cytokines that occurs in vivo, which ultimately dictates the net effects of IMiDs in MM-the understanding of which is necessary to facilitate optimal manipulation of these drugs in future MM management.

Synergistic interactions between the synthetic retinoid tamibarotene and glucocorticoids in human myeloma cells

Tamibarotene (TM411) is a synthetic retinoic acid receptor-alpha/-beta selective retinoid that is chemically more stable than all-trans retinoic acid. This study was designed to evaluate the activity of TM411 in multiple myeloma (MM) and the effects of TM411 combined with a glucocorticoid (GC). In vitro, five human myeloma cells were treated with TM411 alone, GC alone, or TM411 + GC. Cell survival was analyzed by the tetrazolium dye assay and the Hoechst 33342/propidium iodide double-staining method. The effect of TM411 + GC was assessed by the isobologram method. In vivo, the growth-inhibitory effects of the drugs on RPMI-8226 cell xenografts established in SCID mice were examined. The effects of the agents on IL-6-mediated signaling pathways were also analyzed by Western blotting. TM411 was 2- to 10-fold more potent, in terms of its growth-inhibitory effect, than all-trans retinoic acid. The combination of TM411 and GC was found to show a markedly synergistic interaction. While increased expressions of the IL-6 receptor, phosphorylated MAPK, and Akt were observed after exposure to GC, TM411 attenuated this increase in the expressions, suggesting that such modification of the effect of GC by TM411 might be the possible mechanism underlying the synergistic interaction. Furthermore, TM411 + GC showed a supra-additive inhibitory effect in a xenograft model as compared with TM411 or GC alone. These results imply that the combination of TM411 + GC might be highly effective against MM, and suggest the need for clinical evaluation of TM411 + GC for the treatment of MM.

The role of the insulin-like growth factor 1 receptor axis in multiple myeloma

Multiple myeloma remains a fatal B cell malignancy with severe clinical features such as anaemia and bone fractures, caused by the predominant localization of the myeloma cells in the bone marrow (BM). The MM cells first migrate towards the BM, followed by their clonal expansion and induction of angiogenesis and osteolysis. Insulin-like growth factor 1 or IGF-1 is a cytokine which plays a role in myeloma development. Besides serving as a growth and survival factor, it attracts the cells towards the BM, and is involved in the angiogenesis process. This makes the IGF-1R an interesting target for therapeutical interventions. Apart from mediating aspects of the malignant phenotype, it also appears not to be an absolute requirement for normal cell homeostasis. Various strategies targeting the IGF-1R have emerged with the two main strategies being blocking antibodies and small molecule inhibitors. After encouraging preclinical results both strategies are now in clinical trials.

Interleukin-6 in the bone marrow microenvironment promotes the growth and survival of neuroblastoma cells

Neuroblastoma, the second most common solid tumor in children, frequently metastasizes to the bone marrow and the bone. Neuroblastoma cells present in the bone marrow stimulate the expression of interleukin-6 (IL-6) by bone marrow stromal cells (BMSC) to activate osteoclasts. Here we have examined whether stromal-derived IL-6 also has a paracrine effect on neuroblastoma cells. An analysis of the expression of IL-6 and its receptor, IL-6R, in 11 neuroblastoma cell lines indicated the expression of IL-6 in 4 cell lines and of IL-6R in 9 cell lines. Treatment of IL-6R-positive cells with recombinant human IL-6 resulted in signal transducer and activator of transcription-3 and extracellular signal-regulated kinase-1/2 activation. Culturing IL-6R-positive neuroblastoma cells in the presence of BMSC or recombinant human IL-6 increased proliferation and protected tumor cells from etoposide-induced apoptosis, whereas it had no effect on IL-6R-negative tumor cells. In vivo, neuroblastoma tumors grew faster in the presence of a paracrine source of IL-6. IL-6 induced the expression of cyclooxygenase-2 in neuroblastoma cells with concomitant release of prostaglandin-E2, which increased the expression of IL-6 by BMSC. Supporting a role for stromal-derived IL-6 in patients with neuroblastoma bone metastasis, we observed elevated levels of IL-6 in the serum and bone marrow of 16 patients with neuroblastoma bone metastasis and in BMSC derived from these patients. Altogether, the data indicate that stromal-derived IL-6 contributes to the formation of a bone marrow microenvironment favorable to the progression of metastatic neuroblastoma.

Beta1 integrin adhesion enhances IL-6-mediated STAT3 signaling in myeloma cells: implications for microenvironment influence on tumor survival and proliferation

The bone marrow microenvironmental components interleukin (IL)-6 and fibronectin (FN) individually influence the proliferation and survival of multiple myeloma (MM) cells; however, in vivo, these effectors most likely work together. We examined signaling events, cell cycle progression, and levels of drug response in MM cells either adhered to FN via beta1 integrins, stimulated with IL-6, or treated with the two combined. Although G(1)-S cell cycle arrest associated with FN adhesion was overcome when IL-6 was added, the cell adhesion-mediated drug resistance (CAM-DR) was maintained in the presence of IL-6. Concomitant exposure of MM cells to IL-6 and FN adhesion revealed a dramatic increase in signal transducers and activators of transcription 3 (STAT3) phosphorylation, nuclear translocation, and DNA binding, compared with either IL-6 or FN adhesion alone in four MM cell lines. Importantly, this increase in STAT3 activation correlated with a novel association between STAT3 and gp130 in cells adhered to FN before stimulation with IL-6, relative to nonadherent cells. Taken together, these results suggest a mechanism by which collaborative signaling by beta1 integrin and gp130 confers an increased survival advantage to MM cells.

Gene expression of anti- and pro-apoptotic proteins in malignant and normal plasma cells

The survival of malignant plasma cells is a key event in disease occurrence, progression and chemoresistance. Using DNA-microarrays, we analysed the expression of genes coding for 58 proteins linked with extrinsic and intrinsic apoptotic pathways, caspases and inhibitor of apoptosis proteins. We considered six memory B cells (MBC), seven plasmablasts (PPC), seven bone marrow plasma cells (BMPC) and purified myeloma cells (MMC) from 92 newly-diagnosed patients. Forty out of the 58 probe sets enabled the separation of MBC, PPC and BMPC in three homogeneous clusters, characterized by an elevated expression of TNFRSF10A, TNFRSF10B, BCL2A1, CASP8, CASP9 and PMAIP1 genes for MBC, of FAS, FADD, AIFM1, BIRC5, CASP CASP2, CASP3 and CASP6 for PPC and of BCL2, MCL1, BID, BIRC3 and XIAP for BMPC. Thus, B cell differentiation was associated with change of expression of pro-apoptotic and anti-apoptotic genes. Regarding MMC, the major finding was TRAIL upregulation that might be counteracted by a high osteoprotegerin production by BM stromal cells and a decreased expression of FAS, APAF1 and BNIP3 compared to normal BMPC. Out of the 40 genes, CASP2 and BIRC5 expression in MMC had adverse prognosis in two independent series of previously-untreated patients.

In vivo anti-myeloma activity and modulation of gene expression profile induced by valproic acid, a histone deacetylase inhibitor

Valproic acid (VPA) is a well-tolerated anticonvulsant that exerts anti-tumour activity as a histone deacetylase inhibitor. This study investigated the in vitro and in vivo activity of VPA against multiple myeloma (MM) cells. In vitro exposure of interleukin-6-dependent or -independent MM cells to VPA inhibited cell proliferation in a time- and dose-dependent manner and induced apoptosis. In a cohort of severe combined immunodeficiency mice bearing human MM xenografts, VPA induced tumour growth inhibition and survival advantage in treated animals versus controls. Flow cytometric analysis performed on MM cells from excised tumours showed increase of G(0)-G(1) and a decreased G(2)/M- and S-phase following VPA treatment, indicating in vivo effects of VPA on cell cycle regulation. Gene expression profiling of MM cells exposed to VPA showed downregulation of genes involved in cell cycle progression, DNA replication and transcription, as well as upregulation of genes implicated in apoptosis and chemokine pathways. Pathfinder analysis of gene array data identified cell growth, cell cycle, cell death, as well as DNA replication and repair as the most important signalling networks modulated by VPA. Taken together, our data provide the preclinical rationale for VPA clinical evaluation as a single agent or in combination, to improve patient outcome in MM.

Dexamethasone-induced apoptotic mechanisms in myeloma cells investigated by analysis of mutant glucocorticoid receptors

The mechanism by which the glucocorticoid (GC) dexamethasone induces apoptosis in multiple myeloma (MM) cells is unknown, although previous work suggests that either transactivation through the glucocorticoid response element (GRE), transrepression of NF-kappaB, phosphorylation of RAFTK (Pyk2), or induction of Bim is important. We studied this question by ectopically expressing mutant glucocorticoid receptors (GRs) in the dexamethasone-resistant MM1R cell line, which has lost its GR. Lentiviral-mediated reexpression of wild-type GR restored GRE transactivation, NF-kappaB transrepression, RAFTK phosphorylation, Bim induction, and dexamethasone-induced apoptosis. We then reexpressed 4 GR mutants, each possessing various molecular effects, into MM1R cells. A perfect correlation was present between induction of GRE transactivation and induction of apoptosis. In contrast, NF-kappaB transrepression and RAFTK phosphorylation were not required for apoptosis. Although not required for dexamethasone-mediated apoptosis, NF-kappaB inhibition achieved by gene transfer suggested that NF-kappaB transrepression could contribute to apoptosis in dexamethasone-treated cells. Dexamethasone treatment of MM1R cells expressing a mutant incapable of inducing apoptosis successfully resulted in RAFTK (Pyk2) phosphorylation and Bim induction indicating the latter GR-mediated events were not sufficient to induce apoptosis. MM1R cells expressing mutant GRs will be helpful in defining the molecular mechanisms of dexamethasone-induced apoptosis of myeloma cells.

p38 mitogen-activated protein kinase inhibitor LY2228820 enhances bortezomib-induced cytotoxicity and inhibits osteoclastogenesis in multiple myeloma; therapeutic implications

The interaction between multiple myeloma (MM) cells and the bone marrow (BM) microenvironment induces proliferation and survival of MM cells, as well as osteoclastogenesis. This study investigated the therapeutic potential of novel p38 mitogen-activated protein kinase (p38MAPK) inhibitor LY2228820 (LY) in MM. Although cytotoxicity against MM cell lines was modest, LY significantly enhanced the toxicity of bortezomib by down-regulating bortezomib-induced heat shock protein 27 phosphorylation. LY inhibited interleukin-6 secretion from long term cultured-BM stromal cells and BM mononuclear cells (BMMNCs) derived from MM patients in remission. LY also inhibited macrophage inflammatory protein-1alpha secretion from patient MM cells and BMMNCs as well as normal CD14 positive osteoclast precursor cells. Moreover, LY significantly inhibited in vitro osteoclastogenesis from CD14 positive cells induced by macrophage-colony stimulating factor and soluble receptor activator of nuclear factor-kappaB ligand. Finally, LY also inhibited in vivo osteoclatogenesis in a severe combined immunodeficiency mouse model of human MM. These results suggest that LY represents a promising novel targeted approach to improve MM patient outcome both by enhancing the effect of bortezomib and by reducing osteoskeletal events.