New insights into the pathophysiology of multiple myeloma

The diagnostic and therapeutic potential of multiple myeloma-associated circular RNAs

Circular RNA (circRNA) was first discovered in viruses in 1974; they are primarily formed through back splicing, where a downstream splice donor is joined to an upstream splice acceptor, resulting in a closed circRNA transcript. Under normal conditions, most circRNAs are stably expressed; however, in pathological conditions, circRNAs can play critical roles in the disease process of multiple myeloma (MM) through mechanisms such as competing endogenous RNAs (ceRNAs), regulation of transcription and splicing, affecting protein expression and localization, and even direct encoding of peptides. In recent years, there has been increasing interest in the role of circRNAs in MM and their regulatory functions during the disease process. Numerous studies have revealed that circRNAs are involved in the pathogenesis and prognosis of MM, aiding in the identification of reliable prognostic markers and potential therapeutic targets. Therefore, this review summarizes the structural characteristics of circRNAs, and their regulatory roles in MM, and introduces the latest advancements in understanding the novel functions of circRNAs in MM.

Identification of small compounds that inhibit multiple myeloma proliferation by targeting c-Maf transcriptional activity

Multiple myeloma displays the clonal B cell expansion and the overproduction of monoclonal immunoglobulins. Genetic translocations at 14q32, particularly with partners like 16q23, lead to the dysregulation of oncogene expression, including the significant enhancement of c-Maf. This aberrant expression of c-Maf has prompted research into strategies for targeting this transcription factor as a potential therapeutic avenue for multiple myeloma treatment. In this study, we introduce a screening pipeline to test small compounds for their ability to inhibit c-Maf. Using a luciferase indicator driven by the Ccl8 gene promoter, we identified two small compounds that inhibit transcriptional activity of c-Maf. These molecules impede the proliferation of c-Maf-expressing myeloma cells, and repress the expression of c-Maf target genes such as ITGB7 and CCR1. Importantly, these molecules target c-Maf-expressing multiple myeloma cells, but not c-Maf-negative myeloma cells, showing potential for tailoring therapeutic intervention. In conclusion, our screening pipeline is effective to explore leads for a novel c-Maf inhibitor for multiple myeloma therapy.

Effect of interleukin-2 (IL-2) polymorphisms on multiple myeloma: IL-2RA rs2104286, IL-2 rs2069762 and rs2069763 polymorphisms

Interleukin-2 (IL-2) is a cytokine secreted from T helper type 1 cells and released after induction of T helper cells with major histocompatibility complexes or antigens presented by antigen presenting cells. IL-2 activity and gene polymorphisms have been studied in both solid and hematological malignancies. In the present study, it was aimed to examine the effects of IL-2RA rs2104286, IL-2 rs2069762 and rs2069763 polymorphisms on multiple myeloma (MM) susceptibility, progression-free survival (PFS) and overall survival (OS). A total of 300 patients diagnosed with MM in our clinic between January 2010 and January 2021, and 170 healthy individuals were included. In addition to the demographic data of the patients, MM subtypes, initial stages, prognostic index scores, laboratory results, treatment preferences, and survival data were recorded. The genotypes of the IL-2RA rs2104286, IL-2 rs2069762 and rs2069763 polymorphisms were statistically compared between patients and healthy controls to reveal their effects on MM susceptibility and survival. In the statistical analysis performed to examine the effect of IL-2RA rs2104286, IL-2 rs2069762 and rs2069763 polymorphisms on disease susceptibility, no significant difference was found between the patient and healthy control groups. Patients with the TG genotype of IL-2 rs2069762 had a significantly shorter median PFS and OS compared to others. Patients with the GG genotype of IL-2 rs2069763 had a significantly shorter median PFS compared to others. Having the TG genotype of IL-2 rs2069762 has been shown to be protective for short PFS and OS. Our study results will be guiding in terms of IL-2 based therapies, the future for MM and MM epigenetics.

The Clinical Relevance of Selected Cytokines in Newly Diagnosed Multiple Myeloma Patients

Multiple myeloma (MM) is the second most common hematological neoplasm. Cytokines, chemokines, and their receptors, induced by the microenvironment of MM, participate in tumor growth, the attraction of leukocytes, cell homing, and bone destruction. This study aimed to assess the correlation between the pretreatment serum concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8), angiogenic chemokine monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF) and the clinical outcomes and survival of patients newly diagnosed with MM. The study group consisted of 82 individuals. The IL-8 concentration was significantly positively correlated with the age of onset (p = 0.007), the International Staging System (ISS) stage (p = 0.03), the Eastern Cooperative Oncology Group (ECOG) performance status (p < 0.001), the degree of anemia before treatment (p < 0.0001), the degree of kidney disease (p < 0.001), and VEGF (p = 0.0364). Chemotherapy responders had significantly lower concentrations of IL-8 (p < 0.001), IL-6 (p < 0.001), and VEGF (p = 0.04) compared with non-responders. Patients with treatment-induced polyneuropathy had significantly higher levels of IL-8 (p = 0.033). Patients with a high level of IL-6 had a 2-fold higher risk of progression-free survival (PFS) reduction (17 vs. 35 months; HR = 1.89; p = 0.0078), and a more than 2.5-fold higher risk of overall survival (OS) reduction (28 vs. 78 months; HR = 2.62; p < 0.001). High levels of IL-6, IL-8, and VEGF demonstrated significant predictive values for some clinical conditions or outcomes of newly diagnosed MM patients. Patients with an early response to chemotherapy had a significantly lower concentration of these cytokines. A high pretreatment IL-6 concentration was an independent negative prognostic marker for newly diagnosed MM patients.

Integrative analysis of enrichment and prognostic value of ferroptosis-related genes and pathways in multiple myeloma

Ferroptosis is a non-apoptotic form of cell death caused by excessive iron exposure. The role played by the ferroptosis-related genes and pathways in multiple myeloma (MM) is poorly understood. Here, we show that the ferroptosis-related pathways might be involved in tumorigenesis and are closely correlated with the prognosis of MM. The ferroptosis suppressor genes are progressively enriched with the progression of plasma cell dyscrasias. Furthermore, high expression of ferroptosis suppressor genes is correlated with high International Staging System and Revised-ISS staging of MM, as well as the poor outcomes of poor outcomes in progression-free survival and overall survival . The ferroptosis driver genes and the ferroptosis suppressor genes have the opposite effects on the progression and prognosis of MM. Moreover, we reveal that ferroptosis-related genes are associated with cytogenetic abnormalities in MM. The ferroptosis-related pathways and genes might impact the osteogenic differentiation of mesenchymal stromal cells in MM patients. A better understanding of the participation of ferroptosis in MM will pave the way for design of new therapies.

Multiple myeloma: 2022 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Multiple myeloma accounts for approximately 10% of hematologic malignancies.

DIAGNOSIS

The diagnosis requires ≥10% clonal bone marrow plasma cells or a biopsy-proven plasmacytoma plus evidence of one or more multiple myeloma defining events (MDE): CRAB (hypercalcemia, renal failure, anemia, or lytic bone lesions) attributable to the plasma cell disorder, bone marrow clonal plasmacytosis ≥60%, serum involved/uninvolved free light chain (FLC) ratio ≥ 100 (provided involved FLC is ≥100 mg/L), or >1 focal lesion on magnetic resonance imaging.

RISK STRATIFICATION

The presence of del(17p), t(4;14), t(14;16), t(14;20), gain 1q, or p53 mutation is considered high-risk multiple myeloma. The presence of any two high risk factors is considered double-hit myeloma, and three or more high risk factors is triple-hit myeloma.

RISK-ADAPTED INITIAL THERAPY

In patients who are candidates for autologous stem cell transplantation, induction therapy consists of bortezomib, lenalidomide, dexamethasone (VRd) given for approximately 3-4 cycles followed by autologous stem cell transplantation (ASCT). In high-risk patients, daratumumab, bortezomib, lenalidomide, dexamethasone (Dara-VRd) is an alternative to VRd. Selected standard-risk patients can collect stem cells, get additional cycles of induction therapy, and delay transplant until first relapse. Patients who are not candidates for transplant are treated with VRd for approximately 8-12 cycles followed by maintenance or alternatively with daratumumab, lenalidomide, dexamethasone (DRd) until progression.

MAINTENANCE THERAPY

Standard-risk patients need lenalidomide maintenance, while bortezomib plus lenalidomide maintenance is needed for high-risk myeloma.

MANAGEMENT OF RELAPSED DISEASE

A triplet regimen is usually needed at relapse, with the choice of regimen varying with each successive relapse.

Mesenchymal Stem Cells Inhibit the Effects of Dexamethasone in Multiple Myeloma Cells

Mesenchymal stem cells (MSCs) participate in the occurrence and development of multiple myeloma. This study is aimed at exploring whether the presence of MSCs affects dexamethasone's antitumor effects against multiple myeloma. Multiple myeloma cells (OPM-2 and RPMI8226 cells) were cocultured with MSCs with or without dexamethasone. Cell viability was determined by using cell number count, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and colony formation assay, respectively. Cell cycle distribution and cell apoptosis were evaluated by using flow cytometry. The mRNA and protein expressions of target genes were checked by using qRT-PCR and western blotting, respectively. It was found that cell viability of multiple myeloma cells increased in the presence of MSCs. Besides, the presence of MSCs suppressed cell apoptosis induced by dexamethasone via the regulation of BCL-2 (B cell lymphoma 2). The presence of MSCs also affected the effects of dexamethasone on cell cycle distribution. Similarly, LINC00461 overexpression suppressed the inhibition of cell proliferation, suppressed the induction of cell apoptosis, and affected the effects on cell cycle distribution induced by dexamethasone insult. However, LINC00461 knockdown enhanced the inhibitory effects on cell proliferation and the induction of cell apoptosis induced by dexamethasone. In summary, MSCs inhibited the effects of dexamethasone on multiple myeloma and its regulatory effects were associated with LINC00461.

Ubiquitination and Ubiquitin-Like Modifications in Multiple Myeloma: Biology and Therapy

Simple Summary

Multiple myeloma is a cancer of plasma cells causing bone fractures, anemia, renal insufficiency and hypercalcemia. Despite the introduction of new drugs in the past years, it still remains incurable and most patients die from the disease. Multiple myeloma cells are characterized by the production of high amounts of monoclonal antibodies. Therefore, maintaining protein homeostasis from synthesis through folding to degradation is crucial for multiple myeloma cells. While protein ubiquitination and organized degradation are typically considered critical for cellular health, an emerging strategy is to block these processes to induce cell death in disease-state cells characterized by protein over-production. Recent development of compounds that alter the ubiquitin proteasome pathway and drugs that affect ubiquitin-like modifications appear promising in both preclinically and in clinical trials. This review summarizes the impact of protein modifications such as ubiquitination and ubiquitin-like modifications in the biology of multiple myeloma and how it can be exploited to develop new effective therapies for multiple myeloma.

Abstract

Multiple myeloma is a genetically heterogeneous plasma cell malignancy characterized by organ damage and a massive production of (in-)complete monoclonal antibodies. Coping with protein homeostasis and post-translational regulation is therefore essential for multiple myeloma cells to survive. Furthermore, post-translational modifications such as ubiquitination and SUMOylation play key roles in essential pathways in multiple myeloma, including NFκB signaling, epigenetic regulation, as well as DNA damage repair. Drugs modulating the ubiquitin–proteasome system, such as proteasome inhibitors and thalidomide analogs, are approved and highly effective drugs in multiple myeloma. In this review, we focus on ubiquitin and ubiquitin-like modifications in the biology and current developments of new treatments for multiple myeloma.

Multiple myeloma: 2020 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Multiple myeloma accounts for approximately 10% of hematologic malignancies.

DIAGNOSIS

The diagnosis requires ≥10% clonal bone marrow plasma cells or a biopsy proven plasmacytoma plus evidence of one or more multiple myeloma defining events (MDE) namely CRAB (hypercalcemia, renal failure, anemia, or lytic bone lesions) features felt related to the plasma cell disorder, bone marrow clonal plasmacytosis ≥60%, serum involved/uninvolved free light chain (FLC) ratio ≥100 (provided involved FLC is ≥100 mg/L), or >1 focal lesion on magnetic resonance imaging (MRI).

RISK STRATIFICATION

The presence of del(17p), t(4;14), t(14;16), t(14;20), gain 1q, or p53 mutation is considered high-risk multiple myeloma. Presence of any two high risk factors is considered double-hit myeloma; three or more high risk factors is triple-hit myeloma.

RISK-ADAPTED INITIAL THERAPY

In transplant eligible patients, induction therapy consists of bortezomib, lenalidomide, dexamethasone (VRd) given for approximately 3-4 cycles followed by autologous stem cell transplantation (ASCT). In high-risk patients, daratumumab, bortezomib, lenalidomide, dexamethasone (Dara-VRd) is an alternative to VRd. Selected standard risk patients can get additional cycles of induction, and delay transplant until first relapse. Patients not candidates for transplant are typically treated with VRd for approximately 8-12 cycles followed by lenalidomide; alternatively these patients can be treated with daratumumab, lenalidomide, dexamethasone (DRd).

MAINTENANCE THERAPY

After ASCT, standard risk patients need lenalidomide maintenance, while bortezomib-based maintenance is needed for patients with high-risk myeloma.

MANAGEMENT OF REFRACTORY DISEASE

Most patients require a triplet regimen at relapse, with the choice of regimen varying with each successive relapse.

Multiple Myeloma: Available Therapies and Causes of Drug Resistance

Multiple myeloma (MM) is the second most common blood cancer. Treatments for MM include corticosteroids, alkylating agents, anthracyclines, proteasome inhibitors, immunomodulatory drugs, histone deacetylase inhibitors and monoclonal antibodies. Survival outcomes have improved substantially due to the introduction of many of these drugs allied with their rational use. Nonetheless, MM patients successively relapse after one or more treatment regimens or become refractory, mostly due to drug resistance. This review focuses on the main drugs used in MM treatment and on causes of drug resistance, including cytogenetic, genetic and epigenetic alterations, abnormal drug transport and metabolism, dysregulation of apoptosis, autophagy activation and other intracellular signaling pathways, the presence of cancer stem cells, and the tumor microenvironment. Furthermore, we highlight the areas that need to be further clarified in an attempt to identify novel therapeutic targets to counteract drug resistance in MM patients.

Toll-Like Receptor 4 Activation Promotes Multiple Myeloma Cell Growth and Survival Via Suppression of The Endoplasmic Reticulum Stress Factor Chop

Despite recent biomedical improvements in treating Multiple Myeloma (MM), the disease still remains incurable. Toll like receptors (TLRs) provide a link between innate and adaptive immune responses and hence potentially correlate inflammation to cancer. Although the regulatory role of TLRs in MM has been under investigation the underlying mechanisms remain unclear. In this study we assayed the function of TLR4 in MM cell lines and in MM patients' samples. We found that lipopolysaccharide-mediated TLR4 activation increased MM cells proliferation and decreased endoplasmic reticulum (ER) stress-induced apoptosis. Furthermore, we observed that either the endogenous CHOP expression or the ER stress-mediated CHOP induction, were suppressed by TLR4 activation or its overexpression in MM cell lines; TLR4 induction also suppressed ER stress-induced apoptotic signals. In support, TLR4 gene expression silencing in MM cell lines significantly decreased cell proliferation and promoted CHOP and ATF4 upregulation. TLR4 activation was also able to partially abrogate the effect of bortezomib in MM cell lines by suppressing PERK, ATF4 and phospho-eIF2A. We suggest that TLR4-mediated disruption of ER stress responses contributes to MM cells proliferation and suppresses ER-dependent death signals.

Dose Selection for Multiple Myeloma in Modern Era

PURPOSE

The management of multiple myeloma (MM) has evolved over the past 20 years, secondary to novel biologic therapeutics. Radiation therapy remains an important intervention in the management of painful lytic bone lesions. However, the currently used radiation therapy regimens were developed in the pre-biologic therapy era. The goal of this study is to assess the effects of dose and fractionation in pain control for patients with MM in the modern era.

METHODS AND MATERIALS

We conducted a retrospective study based on data collected from patients who received radiation therapy at our institute between 2007 and 2017. A total of 130 patients (266 treatment sites) were included in this study. Univariate Cox proportional hazards models were used to analyze the association of risk of pain recurrence with treatment characteristics and compute the hazard ratios (HRs).

RESULTS

The median follow-up time was 14 months. Patients who received a total dose of 20 to <30 Gy (including 20 Gy) had a significantly lower probability of pain recurrence when compared with those who received <20 Gy (HR, 0.36; 95% confidence interval, 0.14-0.94; P = .0365). There was no statistically significant difference in treatment response or pain recurrence between the different fraction numbers and sizes. However, we noted a trend indicating lower pain recurrence in the group that received 6 to 10 fractions of radiation therapy (P = .06). Among the most commonly used regimens, 8 Gy in a single fraction resulted in a statistically significant increased chance of pain recurrence compared with 20 Gy in 10 fractions and a borderline statistically significant increased chance of pain recurrence when compared with 30 Gy in 10 fractions.

CONCLUSIONS

Radiation therapy remains highly effective at managing lytic bone lesions in patients with MM, and 6- to 10-fraction treatment courses are equally as effective as longer courses at treating these lesions. Treatment with 20 Gy in 10 fractions resulted in a significantly lower probability of pain recurrence when compared with 8 Gy in 1 fraction.

The Safety Profile of Concurrent Therapy for Multiple Myeloma in the Modern Era

Purpose

The management of multiple myeloma has evolved in the modern era, partially owing to the increasing number of biologic therapeutics. Nonetheless, radiation remains an important treatment in the management of painful lytic lesions from multiple myeloma. The goal of this study is to evaluate the side effect profile of radiation therapy (RT) while patients are concurrently treated with biologic agents.

Methods and Materials

We conducted a retrospective study based on data collected from patients receiving RT at our institute from 2007 to 2017. A total of 130 patients (279 treatment sites) were included in this study with a median follow-up time of 14 months. Patients were required to be receiving a biological agent at least within 1 month before starting and up to 1 month after RT. Generalized estimating equations with a log link function and binomial distribution were used to estimate the prevalence ratio (PR) and corresponding 95% confidence interval (CI) and compare the side effects between patients with RT alone and RT + biologic agent.

Results

The median age of all patients in our cohort was 64 years, with 53 men (58.9%) and 37 women (41.1%). The mean Karnofsky performance status score of all cohorts was 80. No significant difference in incidence of acute (PR: 1.33; 95% CI, 0.80-2.22; P = .2660) or subacute (PR: 0.90; 95% CI, 0.49-1.67; P = .7464) toxicities was found between patients with or without biologic agents who were treated concurrently with RT. No significant difference was found in reduction in laboratory values between patients with or without biologic agents treated concurrently with RT for white blood cells (P = .6916), platelets (P = .7779), or hematocrit (P = .0858).

Conclusions

Our study did not detect any significant toxicity rates from palliative radiation while patients were concurrently treated with biologic agents.

Multiple myeloma: 2018 update on diagnosis, risk‐stratification, and management

Disease overview

Multiple myeloma accounts for approximately 10% of hematologic malignancies.

Diagnosis

The diagnosis requires ≥10% clonal bone marrow plasma cells or a biopsy proven plasmacytoma plus evidence of one or more multiple myeloma defining events (MDE): CRAB (hyperc alcemia, r enal failure, a nemia, or lytic b one lesions) features felt related to the plasma cell disorder, bone marrow clonal plasmacytosis ≥60%, serum involved/uninvolved free light chain (FLC) ratio ≥100 (provided involved FLC is ≥100 mg/L), or >1 focal lesion on magnetic resonance imaging.

Risk stratification

Patients with del(17p), t(14;16), and t(14;20) have high-risk multiple myeloma. Patients with t(4;14) translocation and gain(1q) have intermediate-risk. All others are considered standard-risk.

Risk-adapted initial therapy

Initial treatment consists of bortezomib, lenalidomide, dexamethasone (VRd). In high-risk patients, carfilzomib, lenalidomide, dexamethasone (KRd) is an alternative to VRd. In eligible patients, initial therapy is given for approximately 3–4 cycles followed by autologous stem cell transplantation (ASCT). Standard risk patients can opt for delayed ASCT at first relapse. Patients not candidates for transplant are treated with VRd for approximately 8–12 cycles followed by lenalidomide or lenalidomide plus dexamethasone.

Maintenance therapy

After ASCT, lenalidomide maintenance is recommended for standard risk patients, while maintenance with a bortezomib-based regimen is needed for patients with intermediate or high-risk disease.

Management of refractory disease

Most patients require a triplet regimen at relapse, with the choice of regimen varying with each successive relapse. Aggressive relapse with extramedullary plasmacytomas or plasma cell leukemia may require anthracycline containing combination chemotherapy regimens.

Clinical Implications of Targeting XPO1-mediated Nuclear Export in Multiple Myeloma

Multiple myeloma (MM) is a malignancy of plasma cells that is typically chronic, and relapse is common. Current therapeutic strategies include combination and sequential treatments with corticosteroids, alkylating agents, proteasomal inhibitors, immunomodulators, and monoclonal antibodies. These drugs prolong survival but ultimately become ineffective. Exportin 1 (XPO1), a nuclear export protein, is overexpressed in MM cells, and knockdown studies have suggested that XPO1 is essential for MM cell survival. Selective inhibitor of nuclear export (SINE) compounds are novel, orally bioavailable class of agents that specifically inhibit XPO1. Selinexor (KPT-330) is the first-in-human SINE compound. Early phase clinical trials have established the safety profile of this agent and have shown promising efficacy in combination with low-dose dexamethasone and other anti-MM agents. The combination of selinexor and dexamethasone has demonstrated activity in "penta-refractory" MM, (ie, MM refractory to the 5 most active anti-MM agents currently used in treatment). We have reviewed the available data on the molecular implications of XPO1 inhibition in MM. We also reviewed the pertinent early phase clinical data with SINE compounds and discuss management strategies for common toxicities encountered with use of selinexor.

Evaluation of in vitro effects of various targeted drugs on plasma cells and putative neoplastic stem cells in patients with multiple myeloma

Multiple myeloma (MM) is a malignancy characterized by monoclonal paraproteinemia and tissue plasmocytosis. In advanced MM cytopenia and osteopathy may occur. Although several effective treatment strategies have been developed in recent years, there is still a need to identify new drug targets and to develop more effective therapies for patients with advanced MM. We examined the effects of 15 targeted drugs on growth and survival of primary MM cells and 5 MM cell lines (MM.1S, NCI-H929, OPM-2, RPMI-8226, U-266). The PI3-kinase blocker BEZ235, the pan-BCL-2 inhibitor obatoclax, the Hsp90-targeting drug 17AAG, and the Polo-like kinase-1 inhibitor BI2536, were found to exert major growth-inhibitory effects in all 5 MM cell lines tested. Moreover, these drugs suppressed the in vitro proliferation of primary bone marrow-derived MM cells and induced apoptosis at pharmacologic drug concentrations. Apoptosis-inducing effects were not only seen in the bulk of MM cells but also in MM stem cell-containing CD138⁻/CD20⁺/CD27⁺ memory B-cell fractions. Synergistic growth-inhibitory effects were observed in MM cell lines using various drug combinations, including 17AAG+BI2536 in MM.1S, OPM-2, RPMI-8226, and U-266 cells, 17AAG+BEZ235 in MM.1S, OPM-2, RPMI-8226, and U-266 cells, 17AAG+obatoclax in MM.1S, NCI-H929, OPM-2, and RPMI-8226 cells, BI2536+BEZ235 in MM.1S, NCI-H929, OPM-2, and RPMI-8226 cells, BI2536+obatoclax in MM.1S, OPM-2 and RPMI-8226 cells, and BEZ235+obatoclax in MM.1S and RPMI-8226 cells. Together, our data show that various targeted drugs induce profound and often synergistic anti-neoplastic effects in MM cells which may have clinical implications and may contribute to the development of novel treatment strategies in advanced MM.

Endoplasmic reticulum stress in the development of multiple myeloma and drug resistance

Multiple myeloma (MM) is a haematological malignancy of mature antibody‐secreting plasma cells. Currently, MM is incurable, but advances in drug treatments have increased patient lifespan. One of the characteristics of MM is the excessive production of monoclonal immunoglobulin (also referred to as paraprotein). This high level of protein production induces endoplasmic reticulum (ER) stress, and proteasomal degradation of the paraprotein is required to avoid ER stress‐induced cell death. Consequently, proteasomal inhibitors such as bortezomib have been particularly effective therapies. Unfortunately development of resistance to bortezomib is common. In this review, we address how control of endoplasmic reticulum stress is important in the development of MM and how the unfolded protein response and its associated stress response pathways are involved in the development of bortezomib resistance.

Cytogenetic Profiling of Myelomas, Association With Complete Blood Count: Study of 180 Patients

Objectives

To analyze the most common primary and secondary cytogenetic events in myelomas using a probe panel designed in our laboratory, and to associate those events with hematological and biochemical findings.

Methods

Blood specimens from patients diagnosed with myeloma were processed to determine complete blood count and levels of albumin, creatinine, and beta-2 microglobulin. We evaluated bone-marrow specimens for plasma-cell percentage by light microscopy and for cytogenetic abnormalities by fluorescence in situ hybridization (FISH). The Mann-Whitney U test was used to compare hematological and biochemical parameters.

Results

We observed immunoglobulin heavy chain (IgH) gene translocations in 43.3% and t(4;14) in 21% of specimens; t(11;14) was observed in 7.7% of specimens. Gain of chromosomes was observed in 67.2% and loss observed in 16.6% of specimens.

Conclusions

Gains of chromosomes were observed in two-thirds of patients with myeloma. The most common IgH translocation was t(4;14); del13/monosomy13 was the most common secondary cytogenetic abnormality. Partial or complete tetrasomies were associated with higher beta-2 microglobulin levels.

Physical Activity Preferences for People Living With Multiple Myeloma: A Qualitative Study

BACKGROUND

Although physical activity (PA) has significant benefits for people living with multiple myeloma (MM), participation rates are low. Examination of PA preferences will provide important information to clinicians and assist in the development of interventions to increase participation in PA for people living with MM.

OBJECTIVE

The aim of this study is to gain an in-depth understanding of the PA preferences for people living with MM, including the preferred role of clinicians.

METHODS

Semistructured interviews were conducted with patients treated for MM within the preceding 2 to 12 months. Interviews were analyzed using content analysis, where coding categories were derived directly from the text data.

RESULTS

Twenty-four interviews were conducted (women, 54%; age: mean [SD], 62 [8.8] years); 16 (67%) participants had an autologous stem cell transplant. Light- to moderate-intensity PA during and after treatment was feasible, with the strongest preference for a program 2 to 8 months after treatment. The timing of information delivery was important, as was input from clinicians and organizations with knowledge of MM. Preferences for location, structure, and timing of programs varied.

CONCLUSIONS

Low- to moderate-intensity PA after treatment is likely to interest people with MM. Programs need to be flexible and consider individual differences in PA preferences, functional status, and treatment schedules.

IMPLICATIONS

An individually tailored PA program should form part of clinical care, involving clinicians and organizations with expertise in MM. Options for home-based PA are also important. Further research, including a population-based study of people living with MM, is necessary to further quantify PA preferences.

Abnormal repression of SHP-1, SHP-2 and SOCS-1 transcription sustains the activation of the JAK/STAT3 pathway and the progression of the disease in multiple myeloma

Sustained activation of JAK/STAT3 signaling pathway is classically described in Multiple Myeloma (MM). One explanation could be the silencing of the JAK/STAT suppressor genes, through the hypermethylation of SHP-1 and SOCS-1, previously demonstrated in MM cell lines or in whole bone marrow aspirates. The link between such suppressor gene silencing and the degree of bone marrow invasion or the treatment response has not been evaluated in depth. Using real-time RT-PCR, we studied the expression profile of three JAK/STAT suppressor genes: SHP-1, SHP-2 and SOCS-1 in plasma cells freshly isolated from the bone marrows of MM patients and healthy controls. Our data demonstrated an abnormal repression of such genes in malignant plasma cells and revealed a significant correlation between such defects and the sustained activation of the JAK/STAT3 pathway during MM. The repressed expression of SHP-1 and SHP-2 correlated significantly with a high initial degree of bone marrow infiltration but was, unexpectedly, associated with a better response to the induction therapy. Collectively, our data provide new evidences that substantiate the contribution of JAK/STAT suppressor genes in the pathogenesis of MM. They also highlight the possibility that the decreased gene expression of SHP-1 and SHP-2 could be of interest as a new predictive factor of a favorable treatment response, and suggest new potential mechanisms of action of the therapeutic molecules. Whether such defect helps the progression of the disease from monoclonal gammopathy of unknown significance to MM remains, however, to be determined.

Next-generation multiple myeloma treatment: a pharmacoeconomic perspective

Advances in the diagnosis and treatment of multiple myeloma have come at a rapid pace, especially with several new drugs entering the market in the last few years. However, access to and affordability of new treatments poses a major challenge, both in the United States and around the world. High costs of life-saving drugs are detrimental to both the personal finances of the individual patient, as well as society which must bear the increasing costs in terms of increased health insurance premiums, taxes, or both. The challenges are not unique to myeloma, but are commonly encountered in several other cancers as well. But to some extent these pharmacoeconomic concerns are amplified in myeloma due to the need for multidrug regimens that combine 2 or more expensive new drugs, continuous therapy, and the prolonged disease course in most patients. We examine current myeloma therapy from a pharmacoeconomic perspective, and discuss the costs involved. We outline the underlying reasons why cancer drugs are so expensive, the measures that are required to lower cost, and propose potential ways in which costs can be reduced while still delivering high-quality care.

Concomitant reduction of c-Myc expression and PI3K/AKT/mTOR signaling by quercetin induces a strong cytotoxic effect against Burkitt's lymphoma

Burkitt's lymphoma is an aggressive B cell lymphoma whose pathogenesis involves mainly c-Myc translocation and hyperexpression, in addition to antigen-independent BCR signaling and, in some cases, EBV infection. As result of BCR signaling activation, the PI3K/AKT/mTOR pathway results constitutively activated also in the absence of EBV, promoting cell survival and counterbalancing the pro-apoptotic function that c-Myc may also exert. In this study we found that quercetin, a bioflavonoid widely distributed in plant kingdom, reduced c-Myc expression and inhibited the PI3K/AKT/mTOR activity in BL, leading to an apoptotic cell death. We observed a higher cytotoxic effect against the EBV-negative BL cells in comparison with the positive ones, suggesting that this oncogenic gammaherpesvirus confers an additional resistance to the quercetin treatment. Besides cell survival, PI3K/AKT/mTOR pathway also regulates autophagy: we found that quercetin induced a complete autophagic flux in BL cells, that contributes to c-Myc reduction in some of these cells. Indeed, autophagy inhibition by chloroquine partially restored c-Myc expression in EBV-positive (Akata) and EBV-negative (2A8) cells that harbor c-Myc mutation. Interestingly, chloroquine did not affect the quercetin-mediated reduction of c-Myc expression in Ramos cells, that have no c-Myc mutation in the coding region, although autophagy was induced. These results suggest that mutant c-Myc could be partially degraded through autophagy in BL cells, as previously reported for other mutant oncogenic proteins.

Multiple myeloma: 2016 update on diagnosis, risk-stratification, and management

Multiple myeloma accounts for approximately 10% of hematologic malignancies.The diagnosis requires ≥10% clonal bone marrow plasma cells or a biopsy proven plasmacytoma plus evidence of one or more multiple myeloma defining events (MDE): CRAB (hypercalcemia, renal failure, anemia, or lytic bone lesions) features felt related to the plasma cell disorder, bone marrow clonal plasmacytosis ≥60%, serum involved/uninvolved free light chain (FLC) ratio ≥100 (provided involved FLC is ≥100 mg/L), or >1 focal lesion on magnetic resonance imaging. Patients with del(17p), t(14;16), and t(14;20) have high-risk multiple myeloma. Patients with t(4;14) translocation and gain(1q) have intermediate-risk. All others are considered standard-risk. Initial treatment consists of bortezomib, lenalidomide, dexamethasone (VRD). In high-risk patients, carfilzomib, lenalidomide, dexamethasone (KRD) is an alternative to VRD. In eligible patients, initial therapy is given for approximately 3-4 months followed by autologous stem cell transplantation (ASCT). Standard risk patients can opt for delayed ASCT at first relapse. Patients not candidates for transplant are treated with Rd until progression, or alternatively, a triplet regimen such as VRD for approximately 12-18 months. After ASCT, lenalidomide maintenance is considered for standard risk patients especially in those who are not in very good partial response or better, while maintenance with a bortezomib-based regimen is needed for patients with intermediate or high-risk disease. Patients with indolent relapse can be treated with 2-drug or 3-drug combinations. Patients with more aggressive relapse require a triplet regimen or a combination of multiple active agents. Am. J. Hematol. 91:720-734, 2016. © 2016 Wiley Periodicals, Inc.

Multiple Myeloma: Diagnosis and Treatment

The diagnosis and treatment of multiple myeloma has changed dramatically in the past decade. The disease definition has been updated to include highly specific biomarkers in addition to established markers of end-organ damage. The staging system has been revised to combine both measures of tumor burden and disease biology. Advances in therapy have resulted in a marked improvement in overall survival. New drugs introduced in the past few years include carfilzomib, pomalidomide, panobinostat, ixazomib, elotuzumab, and daratumumab. In this review, we outline the current approach to the diagnosis, prognosis, and management of multiple myeloma.

Molecular mechanisms in multiple myeloma drug resistance

Multiple myeloma (MM) is predominantly an incurable malignancy despite high-dose chemotherapy, autologous stem cell transplant and novel agents. MM is a genetically heterogeneous disease and the complexity increases as the disease progresses to a more aggressive stage. MM arises from a plasma cell, which produces and secretes non-functioning immunoglobulins. Most MM cells are sensitive to proteasome inhibitors (PIs), which have become the main drug in the treatment of newly diagnosed and relapsed MM. However, not all MM is sensitive to PIs. This review summarises the literature regarding molecular biology of MM with a focus on the unfolded protein response and explores how this could affect drug sensitivity and progression of disease.

High expression of transforming acidic coiled coil-containing protein 3 strongly correlates with aggressive characteristics and poor prognosis of gastric cancer

Transforming acidic coiled coil-containing protein 3 (TACC3) is well understood to regulate mitotic spindle dynamics and centrosome integrity during mitosis. TACC3 has been suggested to be deregulated in a variety of human malignancies and may be involved in the process of cancer progression. The aim of the present study was to determine the status of TACC3 expression in gastric cancer (GC) and to clarify its clinical/prognostic significance. In the present study, we applied quantitative PCR (qPCR) and western blotting to examine TACC3 mRNA/protein expression in paired GC tissues and matched adjacent non-malignant tissues. Immunohistochemistry (IHC) was performed on a large cohort of 186 postoperative GC samples. Chi-square test, Kaplan-Meier analysis and Cox regression modelling were used to analyse the data. Upregulated mRNA and protein expression levels of TACC3 were observed in the majority of the GC tissues based on qPCR and western blotting compared to the adjacent non-cancerous gastric tissues. Specific IHC staining for TACC3 was predominantly identified in the cytoplasm of the cancer cells. A high expression of TACC3 was detected in 102 of the 186 (54.8%) tissue samples and was significantly associated with the extracapsular extension of the tumour (P<0.001), tumour relapse (P<0.001) and shortened overall survival in GC (P<0.001). Further analysis demonstrated that the TACC3 expression level stratified the patient outcome in stage II (P=0.040), stage III (P<0.001), T3/4 (P<0.001), N positive (P<0.001) and poorly differentiated/undifferentiated tumour subgroups (P<0.001). The Cox regression analysis suggested that a high expression of TACC3 was an independent prognostic factor for GC patients. The measurement of TACC3 protein expression may be beneficial for predicting clinical outcomes for GC patients.

Stem cells and bone diseases: new tools, new perspective

Postnatal skeletal stem cells are a unique class of progenitors with biological properties that extend well beyond the limits of stemness as commonly defined. Skeletal stem cells sustain skeletal tissue homeostasis, organize and maintain the complex architectural structure of the bone marrow microenvironment and provide a niche for hematopoietic progenitor cells. The identification of stem cells in the human post-natal skeleton has profoundly changed our approach to the physiology and pathology of this system. Skeletal diseases have been long interpreted essentially in terms of defective function of differentiated cells and/or abnormal turnover of the matrix that they produce. The notion of a skeletal stem cell has brought forth multiple, novel concepts in skeletal biology that provide potential alternative concepts. At the same time, the recognition of the complex functions played by skeletal progenitors, such as the structural and functional organization of the bone marrow, has provided an innovative, unifying perspective for understanding bone and bone marrow changes simultaneously occurring in many disorders. Finally, the possibility to isolate and highly enrich for skeletal progenitors, enables us to reproduce perfectly normal or pathological organ miniatures. These, in turn, provide suitable models to investigate and manipulate the pathogenetic mechanisms of many genetic and non-genetic skeletal diseases. This article is part of a Special Issue entitled Stem cells and Bone.

MALAT1 long non-coding RNA is overexpressed in multiple myeloma and may serve as a marker to predict disease progression

Background

The pathogenesis of multiple myeloma involves complex genetic and epigenetic events. This study aimed to investigate the role and clinical relevance of the long non-coding RNA (lncRNA), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in multiple myeloma.

Methods

Bone marrow mononuclear cells were collected for analysis. The samples of multiple myeloma were taken from 45 patients at diagnosis, 61 post-treatment, and 18 who relapsed or had progression. Control samples were collected from 20 healthy individuals. Real-time quantitative reverse transcription polymerase chain reactions were performed to evaluate the expression of MALAT1. The clinical relevance of MALAT1 expression was also explored.

Results

MALAT1 was overexpressed in the newly diagnosed patients compared with post-treatment patients (mean ∆C_T: -5.54 ± 0.16 vs. -3.84 ± 0.09, 3.25-fold change; p < 0.001) and healthy individuals (mean ∆C_T: -5.54 ± 0.16 vs. -3.95 ± 0.21, 3.01-fold change; p < 0.001). The expression of MALAT1 strongly correlated with disease status, and the magnitude of change in MALAT1 post-treatment had prognostic relevance. The patients with early progression had a significantly smaller change in MALAT1 after treatment (mean ∆C_T change: 1.26 ± 1.06 vs. 2.09 ± 0.79, p = 0.011). A cut-off value of the change in MALAT1 (∆C_T change: 1.5) was obtained, and the patients with a greater decrease in MALAT1 (difference in ∆C_T >1.5) had significantly longer progression-free survival compared with the patients with a smaller MALAT1 change (24 months vs. 11 months; p = 0.001). For the post-treatment patients, the risk of early progression could be predicted using this cut-off value.

Conclusions

MALAT1 was overexpressed in patients with myeloma and may play a role in its pathogenesis. In addition, MALAT1 may serve as a molecular predictor of early progression.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-809) contains supplementary material, which is available to authorized users.

Extracellular matrix remodeling by bone marrow fibroblast-like cells correlates with disease progression in multiple myeloma

The pathogenesis of multiple myeloma (MM) is regarded as a multistep process, in which an asymptomatic stage of monoclonal gammopathy of undetermined significance (MGUS) precedes virtually all cases of MM. Molecular events characteristic for the transition from MGUS to MM are still poorly defined. We hypothesized that fibroblast-like cells in the tumor microenvironment are critically involved in the pathogenesis of MM. Therefore, we performed a comparative proteome profiling study, analyzing primary human fibroblast-like cells isolated from the bone marrow of MM, of MGUS, as well as of non-neoplastic control patients. Thereby, a group of extracellular matrix (ECM) proteins, ECM receptors, and ECM-modulating enzymes turned out to be progressively up-regulated in MGUS and MM. These proteins include laminin α4, lysyl-hydroxylase 2, prolyl 4-hydroxylase 1, nidogen-2, integrin α5β5, c-type mannose receptor 2, PAI-1, basigin, and MMP-2, in addition to PDGF-receptor β and the growth factor periostin, which are likewise involved in ECM activities. Our results indicate that ECM remodeling by fibroblast-like cells may take place already at the level of MGUS and may become even more pronounced in MM. The identified proteins which indicate the stepwise progression from MGUS to MM may offer new tools for therapeutic strategies.

Celastrol inhibits lipopolysaccharide-induced angiogenesis by suppressing TLR4-triggered nuclear factor-kappa B activation

Celastrol is an active compound extracted from the root bark of the traditional Chinese medicine Tripterygium wilfordii Hook F. In this study, we investigated the effect of celastrol on lipopolysaccharide (LPS)-activated LP-1 human multiple myeloma cell-induced angiogenesis, and identified its molecular mechanism of action. Migration of human umbilical vein endothelial cells (HUVECs) was tested using a wound-healing assay. HUVEC invasion was assayed using a Transwell chamber. Cell surface expression of Toll-like receptor 4 (TLR4) was analyzed by flow cytometry. Angiogenic factor vascular endothelial growth factor (VEGF) level was quantified by LUMINEX and protein expression was analyzed by Western blot. Translocation of nuclear factor-kappa B (NF-κB) was observed by fluorescence microscopy. Celastrol inhibited LPS-stimulated LP-1 human multiple myeloma-induced HUVEC migration and invasion in a concentration-dependent manner. Wound diameters increased by 72.9, 165.4 and 246.2% at 0.025, 0.05 and 0.1 μM, respectively, compared to LPS alone. A 45-74% inhibition of LPS-dependent cell invasion was achieved in the presence of 0.025-0.1 μM celastrol. Celastrol significantly downregulated LPS-induced TLR4 expression and inhibited LPS-induced VEGF secretion in LP-1 cells. VEGF levels decreased by 64.8, 84.4 and 92.9% after coexposure to celastrol at 0.025, 0.05 and 0.1 μM, respectively, compared to LPS alone. Celastrol also inhibited the IκB kinase (IKK)/NF-κB pathway induced by LPS. Protein levels of NF-κB p65, IKKα and IκB-α decreased in a dose-dependent manner after coexposure to celastrol. Celastrol also blocked nuclear translocation of the p65 subunit. These results suggest that celastrol inhibits LPS-induced angiogenesis by suppressing TLR4-triggered NF-κB activation.

Perceived benefits and barriers to exercise for recently treated patients with multiple myeloma: a qualitative study

BACKGROUND

Understanding the physical activity experiences of patients with multiple myeloma (MM) is essential to inform the development of evidence-based interventions and to quantify the benefits of physical activity. The aim of this study was to gain an in-depth understanding of the physical activity experiences and perceived benefits and barriers to physical activity for patients with MM.

METHODS

This was a qualitative study that used a grounded theory approach. Semi-structured interviews were conducted in Victoria, Australia by telephone from December 2011-February 2012 with patients who had been treated for MM within the preceding 2-12 months. Interviews were transcribed and analysed using the constant comparison coding method to reduce the data to themes. Gender differences and differences between treatment groups were explored.

RESULTS

Twenty-four interviews were completed. The sample comprised 13 females (54%), with a mean age of 62 years (SD = 8.8). Sixteen (67%) participants had received an autologous stem cell transplant (ASCT). All participants currently engaged in a range of light to moderate intensity physical activity; walking and gardening were the most common activities. Recovery from the symptoms of MM and side effects of therapy, psychological benefits, social factors and enjoyment were important benefits of physical activity. Barriers to physical activity predominately related to the symptoms of MM and side effects of therapy, including pain, fatigue, and fear of infection. Low self- motivation was also a barrier. Women participated in a more diverse range of physical activities than men and there were gender differences in preferred type of physical activity. Women were more likely to report psychological and social benefits; whereas men reported physical activity as a way to keep busy and self-motivation was a barrier. Patients treated with an ASCT more often reported affective benefits of participation in physical activity and fatigue as a barrier. Patients treated with other therapies (e.g., chemotherapy, radiotherapy) were more likely to report pain as a barrier.

CONCLUSIONS

Patients with MM experience debilitating effects of their condition and therapy, which influences their level and intensity of physical activity participation. Physical activity programs should be individualised; take into consideration gender differences and the impact of different types of therapy on physical activity; and focus on meeting the psychological, coping and recovery needs of patients.

Molecular profiling of multiple myeloma: from gene expression analysis to next-generation sequencing

INTRODUCTION

Multiple myeloma is a fatal malignant proliferation of clonal bone marrow Ig-secreting plasma cells, characterized by wide clinical, biological, and molecular heterogeneity.

AREAS COVERED

Herein, global gene and microRNA expression, genome-wide DNA profilings, and next-generation sequencing technology used to investigate the genomic alterations underlying the bio-clinical heterogeneity in multiple myeloma are discussed.

EXPERT OPINION

High-throughput technologies have undoubtedly allowed a better comprehension of the molecular basis of the disease, a fine stratification, and early identification of high-risk patients, and have provided insights toward targeted therapy studies. However, such technologies are at risk of being affected by laboratory- or cohort-specific biases, and are moreover influenced by high number of expected false positives. This aspect has a major weight in myeloma, which is characterized by large molecular heterogeneity. Therefore, meta-analysis as well as multiple approaches are desirable if not mandatory to validate the results obtained, in line with commonly accepted recommendation for tumor diagnostic/prognostic biomarker studies.

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.

Molecular cytogenetic aberrations in Tunisian patients with multiple myeloma identified by cIg-FISH in fixed bone marrow cells

Cytogenetic studies in multiple myeloma (MM) are hampered by the hypo-proliferative nature of plasma cells. In order to circumvent this problem, we have used a combination of immunolabeling of cytoplasmic Ig light chains (λ or κ) and FISH (cIg-FISH), which allowed a comprehensive detection of the most common and/or recurrent molecular cytogenetic aberrations on fixed bone marrow cells of 70 Tunisian patients. Translocations involving the chromosome 14q32 region were observed in 32 cases (45.7%), including 18 cases with a t(11;14), 8 cases with a t(4;14), and 2 cases with a t(14;16). Deletions of the 13q14 region (D13S319/RB1) were detected in 18.6%, and deletions of the 17p13 region (TP53) in 5.7% of the cases, respectively. Of all patients with a D13S319/RB1 deletion, 61.5% also carried a 14q32 translocation, whereas TP53 deletions were associated with a t(11;14) in 2 cases (50%) and a D13S319 deletion in 1 case (25%). Our results suggest that there is a correlation between the presence of 14q32 translocations and chromosome 13q14 deletions in MM patients and that cIg-FISH is more sensitive as compared to conventional karyotyping in detecting molecular cytogenetic abnormalities in this disease.

Comparative pre-clinical evaluation of receptor tyrosine kinase inhibitors for the treatment of multiple myeloma

BACKGROUND

Fibroblast growth factor receptor 3 (FGFR3) is up-regulated as a result of the t(4;14)(p16;q32) translocation that occurs in up to 20% of multiple myeloma (MM) patients. Recent studies have demonstrated that up-regulation of FGFR3 promotes cell survival, growth and drug resistance in malignant plasma cells, both in vitro and in vivo. Therefore, inhibition of FGFR3 signalling is potential target for the chemotherapeutic intervention in t(4;14) MM.

METHODS

Small molecule receptor tyrosine kinase inhibitors (PD173074, sunitinib (SU-11248), vandetanib (ZD6474) and vatalanib (PTK-787)) with varying degrees of inhibitory activity and selectivity against FGFR, were assessed in Ba/f3 cells expressing ZNF198-FGFR1 and MM cell lines. Cell viability, FGFR3 and ZNF198-FGFR1 phosphorylation and apoptosis were evaluated by growth inhibition assays, immunoblotting and fluorescence-activated cell sorting analysis, respectively. An in vivo study was performed with sunitinib in t(4;14)-positive and t(4;14)-negative human MM tumour xenograft models.

RESULTS

PD173074 and sunitinib differentially inhibited the growth of Ba/f3 cells expressing ZNF198-FGFR1 (GI(50)=10 nM and 730 nM, versus GI(50) >1 μM and 2.7 μM for parental cells; p<0.0001) and t(4;14) positive MM cell lines (GI(50)=4-10 μM and 1-3 μM, versus GI(50)=14-15 μM and 4-5 μM for t(4;14) negative MM cells; p≤0.002). In addition, both PD173074 and sunitinib inhibited the activation of FGFR3 in t(4;14)-positive MM cells. PD173074 and sunitinib induced an apoptotic response in a concentration and time-dependent manner in a t(4;14)-positive (PD174073 and sunitinib) but not a t(4;14)-negative MM cell line (sunitinib only); however, in in vivo tumours derived from the same cell lines, sunitinib was only active in the t(4;14)-negative model.

CONCLUSIONS

These data demonstrate that PD173074 and sunitinib are inhibitors of FGFR3 in MM cell lines, and that sunitinib has in vivo activity in a human MM tumour xenograft model. However, caution should be exercised in using the t(4;14) translocation as a predictive biomarker for patient selection in clinical trials with sunitinib.

The bone marrow stroma in hematological neoplasms--a guilty bystander

In the setting of hematological neoplasms, changes in the bone marrow (BM) stroma might arise from pressure exerted by the neoplastic clone in shaping a supportive microenvironment, or from chronic perturbation of the BM homeostasis. Under such conditions, alterations in the composition of the BM stroma can be profound, and could emerge as relevant prognostic factors. In this Review, we delineate the multifaceted contribution of the BM stroma to the pathobiology of several hematological neoplasms, and discuss the impact of stromal modifications on the natural course of these diseases. Specifically, we highlight the involvement of BM stromal components in lymphoid and myeloid malignancies, and present the most relevant processes responsible for remodeling the BM stroma. The role of bystander BM stromal elements in the setting of hematological neoplasms is discussed, strengthening the rationale for treatment strategies that target the BM stroma.

Discovery of chrysoeriol, a PI3K-AKT-mTOR pathway inhibitor with potent antitumor activity against human multiple myeloma cells in vitro

This study was designed to determine the impact of chrysoeriol on proliferation and cell cycle progression in the human multiple myeloma cell lines RPMI 8226 and KM3, and its related molecular mechanisms. Chryseoriol was identified by using the phosphorylated AKT-specific cytoblot high throughput assay. CCK-8 assay was employed to examine the growth inhibition rate and IC(50) (48 h) in peripheral blood mononuclear cells (PBMNCs), RPMI 8226 and KM3 cells treated with chrysoeriol at various concentrations. Cells were labeled with 5-6-carboxyfluorescein diacetate succinimidyl ester (CFSE), and the proliferation dynamics was detected by flow cytometry and analyzed with ModFit software. The cell cycles of RPMI 8226 and KM3 cells were measured by flow cytometry when the IC(50) concentration of chrysoeriol was adopted. The alterations in cell-cycle related proteins (Cyclin B1, Cyclin D1, p21) and proteins in PI3K-AKT-mTOR pathway were determined by Western blot analysis. The results showed the proliferation of multiple myeloma cells was significantly inhibited by chrysoeriol, resulting in cell cycle arrest in G(2)/M phase. Chrysoeriol could significantly reduce the expression of p-AKT (s473) and p-4eBP1 (t37/46) protein, meanwhile enhanced Cyclin B1 and p21 protein expression. Similar effects were not observed in PBMNCs from normal donors. It was concluded that chrysoeriol was a selective PI3K-AKT-mTOR pathway inhibitor. It restrained the proliferation of human multiple myeloma cells, but didn't affect proliferation of PBMNCs from normal donors. It might exhibit the cell cycle regulatory effect via the inhibition of PI3K-AKT-mTOR signal pathway.

The life span of short-lived plasma cells is partly determined by a block on activation of apoptotic caspases acting in combination with endoplasmic reticulum stress

Apoptosis of short-lived plasma cells after a few days of intense immunoglobulin secretion is critical for maintaining a controlled humoral immune response. The mechanisms that regulate this process are poorly understood. Here we report that the key apoptotic caspases, caspase-3 and caspase-9, become resistant to activation by apoptotic stimuli when B cells differentiate into short-lived plasma cells. As a consequence, apoptosis of most short-lived plasma cells in vitro and in vivo is effector caspase-independent. We also show that a triaspartic acid repeat that normally prevents activation of caspase-3 becomes stabilized in short-lived plasma cells and myeloma cell lines. The block on caspase activation occurs before the accumulation of intracellular immunoglobulins and a progressive rise in secretory stress in the endoplasmic reticulum (ER). Plasma cells show increased susceptibility to ER stress-induced apoptosis and activate the ER-associated caspase-12, which is required specifically for nuclear apoptotic events. In nonlymphoid cells that cannot activate effector caspases, programmed cell death is delayed in response to ER stress. These observations suggest that the block on activation of key apoptotic caspases has evolved in short-lived plasma cells to prolong survival under conditions of ER stress resulting from high-level immunoglobulin secretion.

The Polycomb group protein Bmi-1 is essential for the growth of multiple myeloma cells

Bmi-1 is a member of the Polycomb group family of proteins that function in the epigenetic silencing of genes governing self-renewal, differentiation, and proliferation. Bmi-1 was first identified through its ability to accelerate c-Myc-induced lymphomagenesis. Subsequent studies have further supported an oncogenic role for Bmi-1 in several cancers including those of the breast, lung, prostate, and brain. Using a stable and inducible shRNA system to silence Bmi-1 gene expression, we show a novel role for Bmi-1 in regulating the growth and clonogenic capacity of multiple myeloma cells both in vitro and in vivo. Moreover, to elucidate novel gene targets controlled by Bmi-1, global transcriptional profiling studies were performed in the setting of induced loss of Bmi-1 function. We found that the expression of the proapoptotic gene Bim is negatively regulated by Bmi-1 and that Bim knockdown functionally rescues the apoptotic phenotype induced upon loss of Bmi-1. Therefore, these studies not only highlight Bmi-1 as a cancer-dependent factor in multiple myeloma, but also elucidate a novel antiapoptotic mechanism for Bmi-1 function involving the suppression of Bim.

Interleukin-12 receptor beta2: from cytokine receptor to gatekeeper gene in human B-cell malignancies

Interleukin (IL) -12 is a cytokine that has been extensively characterized for its immunoregulatory activities. IL-12 binds to a heterodimeric receptor composed of the beta1 and beta2 chains. In this review article, we discuss recent findings on the expression and function of IL-12 receptor (IL-12R) in malignant B cells frozen at various stages of differentiation and in their normal counterparts. These studies, together with others performed in Il12rb2 knockout mice, have established the concept that the IL-12Rbeta2 gene is a gatekeeper from cancer. We will delineate three paradigms reflecting the differential expression of IL-12Rbeta2 in different groups of malignant B cells and discuss the therapeutic perspectives stemming from these studies.

Differential repetitive DNA methylation in multiple myeloma molecular subgroups

Multiple myeloma (MM) is characterized by a wide spectrum of genetic changes. Global hypomethylation of repetitive genomic sequences such as long interspersed nuclear element 1 (LINE-1), Alu and satellite alpha (SAT-alpha) sequences has been associated with chromosomal instability in cancer. Methylation status of repetitive elements in MM has never been investigated. In the present study, we used a quantitative bisulfite-polymerase chain reaction pyrosequencing method to evaluate the methylation patterns of LINE-1, Alu and SAT-alpha in 23 human myeloma cell lines (HMCLs) and purified bone marrow plasma cells from 53 newly diagnosed MM patients representative of different molecular subtypes, 7 plasma cell leukemias (PCLs) and 11 healthy controls. MMs showed a decrease of Alu [median: 21.1 %5-methylated cytosine (%5mC)], LINE-1 (70.0%5mC) and SAT-alpha (77.9%5mC) methylation levels compared with controls (25.2, 79.5and 89.5%5mC, respectively). Methylation levels were lower in PCLs and HMCLs compared with MMs (16.7 and 14.8%5mC for Alu, 45.5 and 42.4%5mC for LINE-1 and 33.3 and 43.3%5mC for SAT-alpha, respectively). Notably, LINE-1 and SAT-alpha methylation was significantly lower in the non-hyperdiploid versus hyperdiploid MMs (P = 0.01 and 0.02, respectively), whereas Alu and SAT-alpha methylation was significantly lower in MMs with t(4;14) (P = 0.02 and 0.004, respectively). Finally, we correlated methylation patterns with DNA methyltransferases (DNMTs) messenger RNA levels showing in particular a progressive and significant increase of DNMT1 expression from controls to MMs, PCLs and HMCLs (P < 0.001). Our results indicate that global hypomethylation of repetitive elements is significantly associated with tumor progression in MM and may contribute toward a more extensive stratification of the disease.

Proliferation of NS0 cells in protein-free medium: the role of cell-derived proteins, known growth factors and cellular receptors

NS0 cells proliferate without external supply of growth factors in protein-free media. We hypothesize that the cells produce their own factors to support proliferation. Understanding the mechanisms behind this autocrine regulation of proliferation may open for the novel approaches to improve animal cell processes. The following proteins were identified in NS0 conditioned medium (CM): cyclophilin A, cyclophilin B (CypB), cystatin C, D-dopachrome tautomerase, IL-25, isopentenyl-diphosphate delta-isomerase, macrophage migration inhibitory factor (MIF), beta(2)-microglobulin, Niemann pick type C2, secretory leukocyte protease inhibitor, thioredoxin-1, TNF-alpha, tumour protein translationally controlled 1 and ubiquitin. Further, cDNA microarray analysis indicated that the genes for IL-11, TNF receptor 6, TGF-beta receptor 1 and the IFN-gamma receptor were transcribed. CypB, IFN-alpha/beta/gamma, IL-11, IL-25, MIF, TGF-beta and TNF-alpha as well as the known growth factors EGF, IGF-I/II, IL-6, leukaemia inhibitory factor and oncostatin M (OSM) were excluded as involved in autocrine regulation of NS0 cell proliferation. The receptors for TGF-beta, IGF and OSM are however present in NS0 cell membranes since TGF-beta(1) caused cell death, and IGF-I/II and OSM improved cell growth. Even though no ligand was found, the receptor subunit gp130, active in signal transduction of the IL-6 like proteins, was shown to be essential for NS0 cells as demonstrated by siRNA gene silencing.