Biologic sequelae of nuclear factor-kappaB blockade in multiple myeloma: therapeutic applications

Pathways to therapy resistance: The sheltering effect of the bone marrow microenvironment to multiple myeloma cells

Multiple Myeloma (MM) is a malignant expansion of plasma cells in the bone marrow (BM), resulting in a disease characterized by symptoms of end organ damage from light chain secretion, crowding of the BM, and bone lesions. Although the past two decades have been characterized by numerous novel therapies emerging, the disease remains incurable due to intrinsic or acquired drug resistance. A major player in MM's drug resistance arises from its intimate relationship with the BM microenvironment (BMME). Through stress-inducing conditions, soluble messengers, and physical adhesion to BM elements, the BMME activates numerous pathways in the myeloma cell. This not only propagates myeloma progression through survival and growth signals, but also specific mechanisms to circumvent therapeutic actions. In this review, we provide an overview of the BMME, the role of individual components in MM survival, and various therapy-specific resistance mechanisms reported in the literature.

Antitumor activity of α-pinene in T-cell tumors

T-cell acute leukemia and lymphoma have a poor prognosis. Although new therapeutic agents have been developed, their therapeutic effects are suboptimal. α-Pinene, a monoterpene compound, has an antitumor effect on solid tumors; however, few comprehensive investigations have been conducted on its impact on hematologic malignancies. This report provides a comprehensive analysis of the potential benefits of using α-pinene as an antitumor agent for the treatment of T-cell tumors. We found that α-pinene inhibited the proliferation of hematologic malignancies, especially in T-cell tumor cell lines EL-4 and Molt-4, induced mitochondrial dysfunction and reactive oxygen species accumulation, and inhibited NF-κB p65 translocation into the nucleus, leading to robust apoptosis in EL-4 cells. Collectively, these findings suggest that α-pinene has potential as a therapeutic agent for T-cell malignancies, and further investigation is warranted.

Optimal strategies of oncolytic virus-bortezomib therapy via the apoptotic, necroptotic, and oncolysis signaling network

Bortezomib and oncolytic virotherapy are two emerging targeted cancer therapies. Bortezomib, a proteasome inhibitor, disrupts protein degradation in cells, leading to the accumulation of unfolded proteins that induce apoptosis. On the other hand, virotherapy uses genetically modified oncolytic viruses (OVs) to infect cancer cells, trigger cell lysis, and activate anti-tumor response. Despite progress in cancer treatment, identifying administration protocols for therapeutic agents remains a significant concern, aiming to strike a balance between efficacy, minimizing toxicity, and administrative costs. In this work, optimal control theory was employed to design a cost-effective and efficient co-administration protocols for bortezomib and OVs that could significantly diminish the population of cancer cells via the cell death program with the NF$ \kappa $B-BAX-RIP1 signaling network. Both linear and quadratic control strategies were explored to obtain practical treatment approaches by adapting necroptosis protocols to efficient cell death programs. Our findings demonstrated that a combination therapy commencing with the administration of OVs followed by bortezomib infusions yields an effective tumor-killing outcome. These results could provide valuable guidance for the development of clinical administration protocols in cancer treatment.

Belantamab mafodotin, pomalidomide and dexamethasone in refractory multiple myeloma: a phase 1/2 trial

Due to evolving treatment standards for newly diagnosed multiple myeloma, many patients will be triple-class exposed after initial relapses and have poor survival. Novel therapies and combinations are therefore required to improve outcomes. B cell maturation antigen (BCMA)-targeted biologics have emerged as an important new area of therapeutics for relapsed multiple myeloma. The two-part ALGONQUIN trial evaluated various doses and schedules of the anti-BCMA antibody-drug conjugate belantamab mafodotin plus pomalidomide and dexamethasone for patients who are lenalidomide refractory and proteosome inhibitor exposed. The primary endpoints, including evaluating dose-limiting toxicities, establishing the recommended Part 2 dose (RP2D) and overall response rate for patients treated at the RP2D, were met. Secondary efficacy endpoints included progression-free survival and overall survival. Patients treated on study (N = 87) had a median of three previous regimens and 55.2% were triple-class refractory. At the RP2D the most common adverse events were decrease in best-corrected visual acuity (71.1%), keratopathy (65.8%), fatigue (57.9%), infection (47.4%; 7.9% grade ≥3), neutropenia (39.5%) and thrombocytopenia (39.5%). For RP2D patients (n = 38), the overall response rate was 85.3%, ≥very good partial response 75.7% and estimated two-year progression-free survival 52.8% (95% confidence interval, 33.9% to 82.4%), at a median follow-up of 13.9 months. The RP2D schedule was associated with manageable antibody-drug conjugate-associated corneal adverse events and improved tolerability without compromising efficacy. Belantamab mafodotin plus pomalidomide and dexamethasone induced durable responses with promising overall survival in relapsed multiple myeloma, the results of which are yet to be confirmed in the phase 3 DREAMM-8 study. ClinicalTrials.gov Identifier: NCT03715478 .

Relapsed/Refractory Multiple Myeloma: A Review of Available Therapies and Clinical Scenarios Encountered in Myeloma Relapse

Multiple myeloma remains an incurable disease with the usual disease course requiring induction therapy, autologous stem cell transplantation for eligible patients, and long-term maintenance. Risk stratification tools and cytogenetic alterations help inform individualized therapeutic choices for patients in hopes of achieving long-term remissions with preserved quality of life. Unfortunately, relapses occur at different stages of the course of the disease owing to the biological heterogeneity of the disease. Addressing relapse can be complex and challenging as there are both therapy- and patient-related factors to consider. In this broad scoping review of available therapies in relapsed/refractory multiple myeloma (RRMM), we cover the pharmacologic mechanisms underlying active therapies such as immunomodulatory agents (IMiDs), proteasome inhibitors (PIs), monoclonal antibodies (mAbs), traditional chemotherapy, and Venetoclax. We then review the clinical data supporting the use of these therapies, organized based on drug resistance/refractoriness, and the role of autologous stem cell transplant (ASCT). Approaches to special situations during relapse such as renal impairment and extramedullary disease are also covered. Lastly, we look towards the future by briefly reviewing the clinical data supporting the use of chimeric antigen receptor (CAR-T) therapy, bispecific T cell engagers (BITE), and Cereblon E3 Ligase Modulators (CELMoDs).

Molecular Mechanisms of Cereblon-Interacting Small Molecules in Multiple Myeloma Therapy

Thalidomide analogues (or immunomodulatory imide drugs, IMiDs) are cornerstones in the treatment of multiple myeloma (MM). These drugs bind Cereblon (CRBN), a receptor for the Cullin-ring 4 ubiquitin-ligase (CRL4) complex, to modify its substrate specificity. IMiDs mediate CRBN-dependent engagement and proteasomal degradation of ‘neosubstrates’, Ikaros (IKZF1) and Aiolos (IKZF3), conveying concurrent antimyeloma activity and T-cell costimulation. There is now a greater understanding of physiological CRBN functions, including endogenous substrates and chaperone activity. CRISPR Cas9-based genome-wide screening has further elucidated the complex cellular machinery implicated in IMiD sensitivity, including IKZF1/3-independent mechanisms. New-generation IMiD derivatives with more potent anti-cancer properties—the CELMoDs (Cereblon E3 ligase modulators)—are now being evaluated. Rational drug design also allows ‘hijacking’ of CRL4^CRBN utilising proteolysis targeting chimeras (PROTACs) to convey entirely distinct substrate repertoires. As all these chemotypes—thalidomide, IMiDs, CELMoDs and PROTACs—engage CRBN and modify its functions, we describe them here in aggregate as ‘CRBN-interacting small molecules’ (CISMs). In this review, we provide a contemporary summary of the biological consequences of CRBN modulation by CISMs. Detailed molecular insight into CRBN–CISM interactions now provides an opportunity to more effectively target previously elusive cancer dependencies, representing a new and powerful tool for the implementation of precision medicine.

Atorvastatin-mediated rescue of cancer-related cognitive changes in combined anticancer therapies

Acute administration of trastuzumab (TZB) may induce various forms of cognitive impairment. These cancer-related cognitive changes (CRCC) are regulated by an adverse biological process involving cancer stem cells (CSCs) and IL-6. Recent studies have reported that atorvastatin (ATV) may change the dynamic of cognitive impairment in a combination (TZB+ATV) therapy. In this study, we investigate the mutual interactions between cancer stem cells and the tumor cells that facilitate cognitive impairment during long term TZB therapy by developing a mathematical model that involves IL-6 and the key apoptotic regulation. These include the densities of tumor cells and CSCs, and the concentrations of intracellular signaling molecules (NFκB, Bcl-2, BAX). We apply the mathematical model to a single or combination (ATV+TZB) therapy used in the experiments to demonstrate that the CSCs can enhance CRCC by secreting IL-6 and ATV may interfere the whole regulation. We show that the model can both reproduce the major experimental observation on onset and prevention of CRCC, and suggest several important predictions to guide future experiments with the goal of the development of new anti-tumor and anti-CRCC strategies. Moreover, using this model, we investigate the fundamental mechanism of onset of cognitive impairment in TZB-treated patients and the impact of alternating therapies on the anti-tumor efficacy and intracellular response to different treatment schedules.

A conventional drug, trastuzumab (TZB), was shown to be an effective weapon in killing cancer cells in brain. However, long term treatment of TZB increases the proportion of cancer stem cells (CSCs) in the tumour microenvironment (TME) and induces up-regulation of pro-tumoral molecules such as IL-6 in TME. These cancer cells then become more resistant to this chemotherapy through the IL-mediated up-regulation of NFκB and CSCs. More importantly, these changes in TME result in a serious side effect, cognitive impairment called cancer-related cognitive changes (CRCC). The detailed mechanism of CRCC is still poorly understood. However, cancer patients with chemotherapy-induced cognitive impairment can have long-term or delayed mental changes. In this study, we investigated the fundamental mechanism of CRCC in cancer patients based on experiments and a mathematical model that describes how tumor cells interact with CSCs in response to chemo drugs. In particular, we investigate how TZB-induced CSCs with modified IL-6 landscapes shape the cognitive functions in cancer patients. We showed that the combination treatment with another drug, atorvastatin (ATV), can abrogate the TZB-induced CRCC and enhance the survival probability of cancer patients by synergistic anti-tumor effect. We demonstrate that the cognitive functions and survival rates in cancer patients depend on the apoptotic signaling pathways via the critical communication and IL-6 landscapes of stimulated CTCs.

Multiple Myeloma Relapse Is Associated with Increased NFκB Pathway Activity and Upregulation of the Pro-Survival BCL-2 Protein BFL-1

Multiple myeloma (MM) is a hematological malignancy that is still considered incurable due to the development of therapy resistance and subsequent relapse of disease. MM plasma cells (PC) use NFκB signaling to stimulate cell growth and disease progression, and for protection against therapy-induced apoptosis. Amongst its diverse array of target genes, NFκB regulates the expression of pro-survival BCL-2 proteins BCL-XL, BFL-1, and BCL-2. A possible role for BFL-1 in MM is controversial, since BFL-1, encoded by BCL2A1, is downregulated when mature B cells differentiate into antibody-secreting PC. NFκB signaling can be activated by many factors in the bone marrow microenvironment and/or induced by genetic lesions in MM PC. We used the novel signal transduction pathway activity (STA) computational model to quantify the functional NFκB pathway output in primary MM PC from diverse patient subsets at multiple stages of disease. We found that NFκB pathway activity is not altered during disease development, is irrespective of patient prognosis, and does not predict therapy outcome. However, disease relapse after treatment resulted in increased NFκB pathway activity in surviving MM PC, which correlated with increased BCL2A1 expression in a subset of patients. This suggests that BFL-1 upregulation, in addition to BCL-XL and BCL-2, may render MM PC resistant to therapy-induced apoptosis, and that BFL-1 targeting could provide a new approach to reduce therapy resistance in a subset of relapsed/refractory MM patients.

A novel phosphoramide compound, DCZ0805, shows potent anti-myeloma activity via the NF-κB pathway

BACKGROUND

Multiple myeloma (MM) is a highly aggressive and incurable clonal plasma cell disease with a high rate of recurrence. Thus, the development of new therapies is urgently needed. DCZ0805, a novel compound synthesized from osalmide and pterostilbene, has few observed side effects. In the current study, we intend to investigate the therapeutic effects of DCZ0805 in MM cells and elucidate the molecular mechanism underlying its anti-myeloma activity.

METHODS

We used the Cell Counting Kit-8 assay, immunofluorescence staining, cell cycle assessment, apoptosis assay, western blot analysis, dual-luciferase reporter assay and a tumor xenograft mouse model to investigate the effect of DCZ0805 treatment both in vivo and in vitro.

RESULTS

The results showed that DCZ0805 treatment arrested the cell at the G0/G1 phase and suppressed MM cells survival by inducing apoptosis via extrinsic and intrinsic pathways. DCZ0805 suppressed the NF-κB signaling pathway activation, which may have contributed to the inhibition of cell proliferation. DCZ0805 treatment remarkably reduced the tumor burden in the immunocompromised xenograft mouse model, with no obvious toxicity observed.

CONCLUSION

The findings of this study indicate that DCZ0805 can serve as a novel therapeutic agent for the treatment of MM.

Pomalidomide and Dexamethasone Are Effective in Relapsed or Refractory Multiple Myeloma in a Real-Life Setting: A Multicenter Retrospective Study in Taiwan

Background

The therapeutic options of relapsed or refractory multiple myeloma (RRMM) remain a challenge. The MM-003 trial demonstrated that RRMM patients treated with pomalidomide and dexamethasone (Pom/Dex) have better progression-free survival (PFS) than those treated with high-dose dexamethasone alone. However, the real-world effectiveness of Pom/Dex in these patients in Taiwan remains unclear.

Methods

This multicenter, registry-based study retrospectively reviewed the medical records of 49 consecutive patients undergoing Pom/Dex treatment for RRMM. We investigated the overall response rate (ORR) and PFS in these patients. The patients were stratified into two groups: those who received two (n=33) and those who received more than two (n=16) prior lines of treatment according to the numbers of regimens before Pom/Dex therapy. The differences in ORR and PFS between these two groups were further analyzed. We also analyzed factors attributed to disease progression.

Results

The ORR was 47.7%, and the median PFS was 4.0 months (range, 0.1−21.1). Patients who received two prior lines of treatment had a higher ORR than those who received more than two prior lines of treatment (55.2% vs. 33.3%; p=0.045). The median PFS of these groups was 4.8 and 3.9 months, respectively (p=0.805). Primary lenalidomide refractoriness reduced the risk of myeloma progression following Pom/Dex treatment (hazard ratio, 0.14; p=0.001).

Conclusions

The median PFS following Pom/Dex treatment in Taiwanese RRMM patients in a real-world setting was similar to that reported by the MM-003 trial. Primary lenalidomide refractoriness should not be an obstacle for Pom/Dex treatment in RRMM.

Anticancer Mechanism of Curcumin on Human Glioblastoma

Glioblastoma (GBM) is the most malignant brain tumor and accounts for most adult brain tumors. Current available treatment options for GBM are multimodal, which include surgical resection, radiation, and chemotherapy. Despite the significant advances in diagnostic and therapeutic approaches, GBM remains largely resistant to treatment, with a poor median survival rate between 12 and 18 months. With increasing drug resistance, the introduction of phytochemicals into current GBM treatment has become a potential strategy to combat GBM. Phytochemicals possess multifarious bioactivities with multitarget sites and comparatively marginal toxicity. Among them, curcumin is the most studied compound described as a potential anticancer agent due to its multi-targeted signaling/molecular pathways properties. Curcumin possesses the ability to modulate the core pathways involved in GBM cell proliferation, apoptosis, cell cycle arrest, autophagy, paraptosis, oxidative stress, and tumor cell motility. This review discusses curcumin’s anticancer mechanism through modulation of Rb, p53, MAPK, P13K/Akt, JAK/STAT, Shh, and NF-κB pathways, which are commonly involved and dysregulated in preclinical and clinical GBM models. In addition, limitation issues such as bioavailability, pharmacokinetics perspectives strategies, and clinical trials were discussed.

Expression and Correlation of Cell-Free cIAP-1 and cIAP-2 mRNA in Breast Cancer Patients: A Study from India

BACKGROUND

Inhibitors of apoptosis proteins such as cIAP-1 and cIAP-2 have recently emerged as the key mechanism in resistance to apoptosis in various cancers and lead to cell survival. Therefore, the present study aimed to evaluate the cIAP-1 and cIAP-2 expression in breast cancer patients, as well as their association with overall patient survival.

METHODS

Histopathologically confirmed 100 invasive ductal carcinoma patients and healthy controls were included in the present study. Total RNA extraction was done from the serum sample of the patients; further, 100 ng of total RNA was used to synthesise cDNA from patients' as well as from healthy controls' serum. Quantitative real-time PCR was performed using the maxima SYBR Green dye to study the expression of cIAP-1 and cIAP-2, and beta-actin was used as the internal control.

RESULTS

The study observed that breast cancer patients had 13.50 mean fold increased cIAP-1 mRNA and 8.76 mean fold increased cIAP-2 mRNA expression compared to the control subjects. Breast cancer patients in the TNM stages I, II, III, and IV showed 9.54, 11.80, 15.19, and 16.83 mean fold increased cIAP-1 mRNA expression (p=0.004). Distant organ metastasis, (p=0.008), PR status of breast cancer patients (p < 0.0001), and HER2 status of breast cancer patients (p < 0.0001) were found to be associated with cIAP-1 mRNA expression. Breast cancer patients with different TNM stages such as stages I, II, III, and IV showed 7.8, 8.09, 7.97, and 12.85 mean fold increased cIAP-2 mRNA expression (p=0.0002). Breast cancer patients with distant organ metastases status were found to be associated with cIAP-2 mRNA expression (p < 0.0001). Breast cancer patients with <13-fold and >13-fold cIAP-1 mRNA expression showed 37.39 months and 34.70 months of overall median survival, and the difference among them was found to be significant (p=0.0001). However, cIAP-2 mRNA expression among <8-fold and >8-fold mRNA expression groups showed 35 months and 27.90 months of overall median survival time (p < 0.0001). Higher cIAP-1 mRNA expression was linked with smoking and alcoholism among the breast cancer patients (p < 0.0001 and p < 0.0001). Significant association of higher cIAP-1 mRNA expression was found with the advancement of the disease, while higher mRNA expression of cIAP-1 was associated with distant organ metastases in ROC curve analysis.

CONCLUSION

The present study suggested that increased cell-free cIAP-1 and cIAP-2 mRNA expression was correlated with the advancement of disease, progression of disease, and overall reduced patient survival. Cell-free cIAP-1 and cIAP-2 mRNA expression could be the predictive indicator of the disease.

Thermally Targeted p50 Peptide Inhibits Proliferation and Induces Apoptosis of Breast Cancer Cell Lines

The application of rationally designed therapeutic peptides (TP) may improve outcomes in cancer treatment. These peptides hold the potential to directly target proliferative pathways and stimulate cell arrest or death pathways. Elastin-like polypeptide (ELP) is an elastin derived biopolymer that undergoes a thermally mediated phase transition. This study employs p50, a nuclear localization sequence derived peptide that inhibits the activation of NFκB and is implicated in cancer cell survival and metastasis. In order to effectively delivery p50, it is conjugated to SynB1-ELP1, a thermally responsive macromolecular carrier. By applying an external heat source, mild hyperthermic conditions (41 °C) induce aggregation and therefore can be used to specifically target ELP to solid tumors in cancer therapy. The addition of a cell penetrating peptide (CPP) to the N-terminus of the macromolecular carrier enhances the cellular uptake and directs the subcellular localization of the bioactive peptide. The novel TP, p50, inhibits proliferation and induces apoptosis of breast cancer cells by blocking the intranuclear import of NFκB. By expanding the repertoire of oncogenic targets, CPPs, and ELP carrier sizes, ELP-based polypeptides may be modulated to optimize the delivery of these novel therapies and allow for the flexibility to create individualized cancer therapies.

Targeting Ubiquitin-Proteasome Pathway by Natural Products: Novel Therapeutic Strategy for Treatment of Neurodegenerative Diseases

Misfolded proteins are the main common feature of neurodegenerative diseases, thereby, normal proteostasis is an important mechanism to regulate the neural survival and the central nervous system functionality. The ubiquitin-proteasome system (UPS) is a non-lysosomal proteolytic pathway involved in numerous normal functions of the nervous system, modulation of neurotransmitter release, synaptic plasticity, and recycling of membrane receptors or degradation of damaged and regulatory intracellular proteins. Aberrant accumulation of intracellular ubiquitin-positive inclusions has been implicated to a variety of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington disease (HD), Amyotrophic Lateral Sclerosis (ALS), and Multiple Myeloma (MM). Genetic mutation in deubiquitinating enzyme could disrupt UPS and results in destructive effects on neuron survival. To date, various agents were characterized with proteasome-inhibitory potential. Proteins of the ubiquitin-proteasome system, and in particular, E3 ubiquitin ligases, may be promising molecular targets for neurodegenerative drug discovery. Phytochemicals, specifically polyphenols (PPs), were reported to act as proteasome-inhibitors or may modulate the proteasome activity. PPs modify the UPS by means of accumulation of ubiquitinated proteins, suppression of neuronal apoptosis, reduction of neurotoxicity, and improvement of synaptic plasticity and transmission. This is the first comprehensive review on the effect of PPs on UPS. Here, we review the recent findings describing various aspects of UPS dysregulation in neurodegenerative disorders. This review attempts to summarize the latest reports on the neuroprotective properties involved in the proper functioning of natural polyphenolic compounds with implication for targeting ubiquitin-proteasome pathway in the neurodegenerative diseases. We highlight the evidence suggesting that polyphenolic compounds have a dose and disorder dependent effects in improving neurological dysfunctions, and so their mechanism of action could stimulate the UPS, induce the protein degradation or inhibit UPS and reduce protein degradation. Future studies should focus on molecular mechanisms by which PPs can interfere this complex regulatory system at specific stages of the disease development and progression.

Challenges for Immunotherapy in Multiple Myeloma: Bone Marrow Microenvironment-Mediated Immune Suppression and Immune Resistance

The power of immunotherapy in the battle of Multiple Myeloma (MM) started with allogeneic stem cell transplantation, and was rediscovered with immunomodulatory drugs and extended with the outstanding results achieved with targeted antibodies. Today, next to powerful antibodies Elotuzumab and Daratumumab, several T-cell-based immunotherapeutic approaches, such as bispecific antibodies and chimeric antigen receptor-transduced T-cells (CAR T-cells) are making their successful entry in the immunotherapy arena with highly promising results in clinical trials. Nonetheless, similar to what is observed in chemotherapy, MM appears capable to escape from immunotherapy, especially through tight interactions with the cells of the bone marrow microenvironment (BM-ME). This review will outline our current understanding on how BM-ME protects MM-cells from immunotherapy through immunosuppression and through induction of intrinsic resistance against cytotoxic effector mechanisms of T- and NK-cells.

Monocytic Myeloid Derived Suppressor Cells in Hematological Malignancies

In the era of novel agents and immunotherapies in solid and liquid tumors, there is an emerging need to understand the cross-talk between the neoplastic cells, the host immune system, and the microenvironment to mitigate proliferation, survival, migration and resistance to drugs. In the microenvironment of hematological tumors there are cells belonging to the normal bone marrow, extracellular matrix proteins, adhesion molecules, cytokines, and growth factors produced by both stromal cells and neoplastic cells themselves. In this context, myeloid suppressor cells are an emerging sub-population of regulatory myeloid cells at different stages of differentiation involved in cancer progression and chronic inflammation. In this review, monocytic myeloid derived suppressor cells and their potential clinical implications are discussed to give a comprehensive vision of their contribution to lymphoproliferative and myeloid disorders.

Monocytic Myeloid Derived Suppressor Cells in Hematological Malignancies

In the era of novel agents and immunotherapies in solid and liquid tumors, there is an emerging need to understand the cross-talk between the neoplastic cells, the host immune system, and the microenvironment to mitigate proliferation, survival, migration and resistance to drugs. In the microenvironment of hematological tumors there are cells belonging to the normal bone marrow, extracellular matrix proteins, adhesion molecules, cytokines, and growth factors produced by both stromal cells and neoplastic cells themselves. In this context, myeloid suppressor cells are an emerging sub-population of regulatory myeloid cells at different stages of differentiation involved in cancer progression and chronic inflammation. In this review, monocytic myeloid derived suppressor cells and their potential clinical implications are discussed to give a comprehensive vision of their contribution to lymphoproliferative and myeloid disorders.

Synergistic Effects of Bortezomib-OV Therapy and Anti-Invasive Strategies in Glioblastoma: A Mathematical Model

It is well-known that the tumor microenvironment (TME) plays an important role in the regulation of tumor growth and the efficacy of anti-tumor therapies. Recent studies have demonstrated the potential of combination therapies, using oncolytic viruses (OVs) in conjunction with proteosome inhibitors for the treatment of glioblastoma, but the role of the TME in such therapies has not been studied. In this paper, we develop a mathematical model for combination therapies based on the proteosome inhibitor bortezomib and the oncolytic herpes simplex virus (oHSV), with the goal of understanding their roles in bortezomib-induced endoplasmic reticulum (ER) stress, and how the balance between apoptosis and necroptosis is affected by the treatment protocol. We show that the TME plays a significant role in anti-tumor efficacy in OV combination therapy, and illustrate the effect of different spatial patterns of OV injection. The results illustrate a possible phenotypic switch within tumor populations in a given microenvironment, and suggest new anti-invasion therapies.

The power of proteasome inhibition in multiple myeloma

INTRODUCTION

Proteasome inhibitors (PIs) are therapeutic backbones of multiple myeloma treatment, with PI-based therapies being standards of care throughout the treatment algorithm. Proteasome inhibition affects multiple critical signaling pathways in myeloma cells and interacts synergistically with mechanisms of action of other conventional and novel agents, resulting in substantial anti-myeloma activity and at least additive effects. Areas covered: This review summarizes the biologic effects of proteasome inhibition in myeloma and provides an overview of the importance of proteasome inhibition to the current treatment algorithm. It reviews key clinical data on three PIs, specifically bortezomib, carfilzomib, and ixazomib; assesses ongoing phase 3 trials with these agents; and looks ahead to the increasingly broad role of both approved PIs and PIs under investigation in the frontline and relapsed settings. Expert commentary: Progress to date with PIs in multiple myeloma has been impressive, but there remain unmet needs and challenges, as well as increasing opportunities to optimize the use of these agents. Understanding discrepancies between PIs in terms of efficacy and safety profile is a key goal of ongoing research, along with proteomics-based efforts to identify potential biomarkers of sensitivity and resistance, thereby enabling increasingly personalized treatment approaches in the future.

Multiple Myeloma and Bone: The Fatal Interaction

Multiple myeloma (MM) is the second-most-common hematologic malignancy and the most frequent cancer to involve bone. MM bone disease (MMBD) has devastating consequences for patients, including dramatic bone loss, severe bone pain, and pathological fractures that markedly decrease the quality of life and impact survival of MM patients. MMBD results from excessive osteoclastic bone resorption and persistent suppressed osteoblastic bone formation, causing lytic lesions that do not heal, even when patients are in complete and prolonged remission. This review discusses the cellular and molecular mechanisms that regulate the uncoupling of bone remodeling in MM, the effects of MMBD on tumor growth, and potential therapeutic approaches that may prevent severe bone loss and repair damaged bone in MM patients.

The proteasome and proteasome inhibitors in multiple myeloma

Proteasome inhibitors are one of the most important classes of agents to have emerged for the treatment of multiple myeloma in the past two decades, and now form one of the backbones of treatment. Three agents in this class have been approved by the United States Food and Drug Administration-the first-in-class compound bortezomib, the second-generation agent carfilzomib, and the first oral proteasome inhibitor, ixazomib. The success of this class of agents is due to the exquisite sensitivity of myeloma cells to the inhibition of the 26S proteasome, which plays a critical role in the pathogenesis and proliferation of the disease. Proteasome inhibition results in multiple downstream effects, including the inhibition of NF-κB signaling, the accumulation of misfolded and unfolded proteins, resulting in endoplasmic reticulum stress and leading to the unfolded protein response, the downregulation of growth factor receptors, suppression of adhesion molecule expression, and inhibition of angiogenesis; resistance to proteasome inhibition may arise through cellular responses mediating these downstream effects. These multiple biologic consequences of proteasome inhibition result in synergistic or additive activity with other chemotherapeutic and targeted agents for myeloma, and proteasome inhibitor-based combination regimens have become established as a cornerstone of therapy throughout the myeloma treatment algorithm, incorporating agents from the other key classes of antimyeloma agents, including the immunomodulatory drugs, monoclonal antibodies, and histone deacetylase inhibitors. This review gives an overview of the critical role of the proteasome in myeloma and the characteristics of the different proteasome inhibitors and provides a comprehensive summary of key clinical efficacy and safety data with the currently approved proteasome inhibitors.

Heme oxygenase-1 nuclear translocation regulates bortezomibinduced cytotoxicity and mediates genomic instability in myeloma cells

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by an accumulation of clonal plasma cells in the bone marrow leading to bone destruction and bone marrow failure. Several molecular mechanisms underlie chemoresistance among which heme oxygenase-1 (HO-1) could play a major role. The aim of the present research was to evaluate the impact of HO-1 in MM following bortezomib (BTZ) treatment and how HO-1 is implicated in the mechanisms of chemoresistance. MM cells were treated for 24h with BTZ (15 nM), a boronic acid dipeptide inhibitor of the 26S proteasome used in the treatment of patients with MM as first-line therapy. We evaluated cell viability, reactive oxygen species (ROS) formation, endoplasmic reticulum (ER) stress, HO-1 expression and compartmentalization and cellular genetic instability. Results showed that BTZ significantly reduced cell viability in different MM cell lines and induced ER-stress and ROS formation. Concomitantly, we observed a significant overexpression of both HO-1 gene and protein levels. This effect was abolished by concomitant treatment with 4-phenybutirric acid, a molecular chaperone, which is known to reduce ER-stress. Surprisingly, inhibition of HO activity with SnMP (10μM) failed to increase BTZ sensitivity in MM cells whereas inhibition of HO-1 nuclear translocation by E64d, a cysteine protease inhibitor, increased sensitivity to BTZ and decreased genetic instability as measured by cytokinesis-block micronucleus assay. In conclusion, our data suggest that BTZ sensitivity depends on HO-1 nuclear compartmentalization and not on its enzymatic activity and this finding may represent an important tool to overcome BTZ chemoresistance in MM patients.

Characterization and use of the novel human multiple myeloma cell line MC-B11/14 to study biological consequences of CRISPR-mediated loss of immunoglobulin A heavy chain

The genetic abnormalities underlying multiple myeloma (MM) are notoriously complex and intraclonal heterogeneity is a common disease feature. In the current study, we describe the establishment of a monoclonal immunoglobulin A (IgA) kappa (κ) MM cell line designated MC-B11/14. Cytogenetic and fluorescence in situ hybridization analyses of the original and relapse patient samples revealed that the MM clone was nonhyperdiploid and possessed an 11;14 chromosomal translocation. The MC-B11/14 cell line, established from the relapse sample, is tetraploid and houses the t(11;14) abnormality. Given our long-standing interest in Ig function and secretion, we next used CRISPR technology to knock out IgA heavy-chain expression in the MC-B11/14 cells to assess the biological consequences of converting this cell line to one only expressing κ light chains. As expected, secretion of intact IgA was undetectable from MC-B11/14^IgA- cells. Sensitivity to pomalidomide treatment was similar between the MC-B11/14^WT and MC-B11/14^IgA- cells; however, MC-B11/14^IgA- cells were found to be significantly more resistant to bortezomib treatment. This study describes the establishment of a new human MM cell line tool with which to study disease biology and the use of CRISPR technology to create a potentially useful model with which to study MM light-chain escape.

Body fat composition as predictive factor for treatment response in patients with newly diagnosed multiple myeloma - subgroup analysis of the prospective GMMG MM5 trial

INTRODUCTION/BACKGROUND

Obesity is a well-known risk factor for malignant tumors and increased body mass index (BMI) is correlated to the risk of developing multiple myeloma (MM). The correlation of body fat composition with disease activity, adverse events and treatment response of MM patients has not been investigated yet.

PATIENTS AND METHODS

A subgroup of 108 patients from a single institution enrolled in the prospective GMMG-MM5 trial, who received a whole-body low-dose computed tomography (WBLDCT) before induction therapy, were included in this study. Body fat composition was measured in WBLDCT for each patient, divided in the compartments abdomen, pelvis, thigh and further categorized in subcutaneous (SAT) and visceral adipose tissue (VAT). The correlation of these parameters with disease activity (M protein, plasma cell count, LDH, CRAB-criteria), adverse cytogenetics, adverse events and treatment response were evaluated.

RESULTS

Significant reciprocal correlation was found between adverse cytogenetics and VAT of the abdomen and pelvis, respectively (gain 1q21: p=0.009 and p=0.021; t(4;14): p=0.038 and p=0.042). No correlation of VAT or SAT with adverse events was observed. Significant reciprocal correlation was observed between abdominal (p=0.03) and pelvic (p=0.035) VAT and treatment response. Abdominal VAT remains significant (p=0.034) independently of revised ISS stage and treatment. The BMI did not show a significant correlation with treatment response or investigated cytogenetics.

CONCLUSION

Based on the clinically relevant difference in treatment outcome depending on VAT and SAT, excessive body fat of abdomen and pelvis might be a predictive factor for poor treatment response. Further influences in this context should be considered as well, e.g. chemotherapy dosing and body fat metabolism. Further studies are necessary to investigate this hypothesis.

MUC1-C is a target in lenalidomide resistant multiple myeloma

Lenalidomide (LEN) acts directly on multiple myeloma (MM) cells by inducing cereblon-mediated degradation of interferon regulatory factor 4, Ikaros (IKZF)1 and IKZF3, transcription factors that are essential for MM cell survival. The mucin 1 (MUC1) C-terminal transmembrane subunit (MUC1-C) oncoprotein is aberrantly expressed by MM cells and protects against reactive oxygen species (ROS)-mediated MM cell death. The present studies demonstrate that targeting MUC1-C with GO-203, a cell-penetrating peptide inhibitor of MUC1-C homodimerization, is more than additive with LEN in downregulating the WNT/β-catenin pathway, suppressing MYC, and inducing late apoptosis/necrosis. We show that the GO-203/LEN combination acts by synergistically increasing ROS and, in turn, suppressing β-catenin. LEN resistance has been linked to activation of the WNT/β-catenin→CD44 pathway. In this regard, our results further demonstrate that targeting MUC1-C is effective against LEN-resistant MM cells. Moreover, GO-203 resensitized LEN-resistant MM cells to LEN treatment in association with suppression of β-catenin and CD44. Targeting MUC1-C also resulted in downregulation of CD44 on the surface of primary MM cells. These findings, and the demonstration that expression of MUC1 and CD44 significantly correlate in microarrays from primary MM cells, provide support for combining GO-203 with LEN in the treatment of MM and in LEN-resistance.

Overexpression of RKIP and its cross-talk with several regulatory gene products in multiple myeloma

Multiple myeloma (MM) is a clonal plasma-cell neoplastic disorder arising from an indolent premalignant disease known as monoclonal gammopathy of undetermined significance (MGUS). MM is a biologically complex heterogeneous disease reflected by its variable clinical responses of patients receiving the same treatment. Therefore, a molecular identification of stage-specific biomarkers will support a more individualized precise diagnostic/prognostic approach, an effective therapeutic regime, and will assist in the identification of novel therapeutic molecular targets. The metastatic suppressor/anti-resistance factor Raf-1 kinase inhibitor protein (RKIP) is poorly expressed in the majority of cancers and is often almost absent in metastatic tumors. RKIP inhibits the Raf/MEK/ERK1/2 and the NF-κB pathways. Whereby all tumors examined exhibited low levels of RKIP, in contrast, our recent findings demonstrated that RKIP is overexpressed primarily in its inactive phosphorylated form in MM cell lines and patient-derived tumor tissues. The underlying mechanism of RKIP overexpression in MM, in contrast to other tumors, is not known. We examined transcriptomic datasets on Oncomine platform (Life Technologies) for the co-expression of RKIP and other gene products in both pre-MM and MM. The transcription of several gene products was found to be either commonly overexpressed (i.e., RKIP, Bcl-2, and DR5) or underexpressed (i.e., Bcl-6 and TNFR2) in both pre-MM and MM. Noteworthy, a significant inverse correlation of differentially expressed pro-apoptotic genes was observed in pre-MM: overexpression of Fas and TNF-α and underexpression of YY1 versus expression of anti-apoptotic genes in MM: overexpression of YY1 and underexpression of Fas and TNF-α. Based on the analysis on mRNA levels and reported studies on protein levels of the above various genes, we have constructed various schemes that illustrate the possible cross-talks between RKIP (active/inactive) and the identified gene products that underlie the mechanism of RKIP overexpression in MM. Clearly, such cross-talks would need to be experimentally validated in both MM cell lines and patient-derived tumor tissues. If validated, the differential molecular signatures between pre-MM and MM might lead to a more precise diagnosis/prognosis of the disease and disease stages and will also identify novel molecular therapeutic targets for pre-MM and MM.

Novel Proteasome Inhibitors and Histone Deacetylase Inhibitors: Progress in Myeloma Therapeutics

The unfolded protein response is responsible for the detection of misfolded proteins and the coordination of their disposal and is necessary to maintain the cellular homoeostasis. Multiple myeloma cells secrete large amounts of immunoglobulins, proteins that need to be correctly folded by the chaperone system. If this process fails, the misfolded proteins have to be eliminated by the two main garbage-disposal systems of the cell: proteasome and aggresome. The blockade of either of these systems will result in accumulation of immunoglobulins and other toxic proteins in the cytoplasm and cell death. The simultaneous inhibition of the proteasome, by proteasome inhibitors (PIs) and the aggresome, by histone deacetylase inhibitors (HDACi) results in a synergistic increase in cytotoxicity in myeloma cell lines. This review provides an overview of mechanisms of action of second-generation PIs and HDACi in multiple myeloma (MM), the clinical results currently observed with these agents and assesses the potential therapeutic impact of the different agents in the two classes. The second-generation PIs offer benefits in terms of increased efficacy, reduced neurotoxicity as off-target effect and may overcome resistance to bortezomib because of their different chemical structure, mechanism of action and biological properties. HDACi with anti-myeloma activity in clinical development discussed in this review include vorinostat, panobinostat and selective HDAC6 inhibitor, ricolinostat.

The Role of PI3K Isoforms in Regulating Bone Marrow Microenvironment Signaling Focusing on Acute Myeloid Leukemia and Multiple Myeloma

Despite the development of novel treatments in the past 15 years, many blood cancers still remain ultimately fatal and difficult to treat, particularly acute myeloid leukaemia (AML) and multiple myeloma (MM). While significant progress has been made characterising small-scale genetic mutations and larger-scale chromosomal translocations that contribute to the development of various blood cancers, less is understood about the complex microenvironment of the bone marrow (BM), which is known to be a key player in the pathogenesis of chronic lymphocytic leukaemia (CLL), AML and MM. This niche acts as a sanctuary for the cancerous cells, protecting them from chemotherapeutics and encouraging clonal cell survival. It does this by upregulating a plethora of signalling cascades within the malignant cell, with the phosphatidylinositol-3-kinase (PI3K) pathway taking a critical role. This review will focus on how the PI3K pathway influences disease progression and the individualised role of the PI3K subunits. We will also summarise the current clinical trials for PI3K inhibitors and how these trials impact the treatment of blood cancers.

Proteasome inhibitors in cancer therapy: Treatment regimen and peripheral neuropathy as a side effect

Proteasomal system plays an important role in protein turnover, which is essential for homeostasis of cells. Besides degradation of oxidized proteins, it is involved in the regulation of many different signaling pathways. These pathways include mainly cell differentiation, proliferation, apoptosis, transcriptional activation and angiogenesis. Thus, proteasomal system is a crucial target for treatment of several diseases including neurodegenerative diseases, cystic fibrosis, atherosclerosis, autoimmune diseases, diabetes and cancer. Over the last fifteen years, proteasome inhibitors have been tested to highlight their mechanisms of action and used in the clinic to treat different types of cancer. Proteasome inhibitors are mainly used in combinational therapy along with classical chemo-radiotherapy. Several studies have proved their significant effects but serious side effects such as peripheral neuropathy, limits their use in required effective doses. Recent studies focus on peripheral neuropathy as the primary side effect of proteasome inhibitors. Therefore, it is important to delineate the underlying mechanisms of peripheral neuropathy and develop new inhibitors according to obtained data. This review will detail the role of proteasome inhibition in cancer therapy and development of peripheral neuropathy as a side effect. Additionally, new approaches to prevent treatment-limiting side effects will be discussed in order to help researchers in developing effective strategies to overcome side effects of proteasome inhibitors.

Autocrine and Paracrine Interactions between Multiple Myeloma Cells and Bone Marrow Stromal Cells by Growth Arrest-specific Gene 6 Cross-talk with Interleukin-6

The pathogenesis of multiple myeloma (MM) has not yet been fully elucidated. Our microarray analysis and immunohistochemistry revealed significant up-regulation of growth arrest-specific gene 6 (Gas6), a vitamin K-dependent protein with a structural homology with protein S, in bone marrow (BM) cells of MM patients. ELISA showed that the serum levels of soluble Gas6 were significantly increased in the MM patients when compared with healthy controls. Gas6 was overexpressed in the human CD138-positive MM cell line RPMI-8226. Exogenous Gas6 suppressed apoptosis induced by serum deprivation and enhanced cell proliferation of the MM cells. The conditional medium from the human BM stromal cell line HS-5 induced cell proliferation and anti-apoptosis of the MM cells with extracellular signal-regulated kinase, Akt, and nuclear factor-κB phosphorylation, which were reversed by the neutralizing antibody to Gas6 or IL-6. The TAM family receptor Mer, which has been identified as a Gas6 receptor, was overexpressed in BM cells of MM patients. The knockdown of Mer by siRNA inhibited cell proliferation, anti-apoptosis, and up-regulation of intercellular cell adhesion molecule-1 (ICAM-1) in MM cells stimulated by an HS-5 cell-conditioned medium. Furthermore, the Gas6-neutralizing antibody reduced the up-regulation of IL-6 and ICAM-1 induced by a HS-5 cell-conditioned medium in MM cells. The present study provides new evidence that autocrine and paracrine stimulation of Gas6 in concert with IL-6 contributes to the pathogenesis of MM, suggesting that Gas6-Mer-related signaling pathways may be a promising novel target for treating MM.

Analysis of TNF-related apoptosis-inducing ligand and receptors and implications in thymus biology and myasthenia gravis

Myasthenia Gravis is an autoantibody-mediated, neuromuscular junction disease, and is usually associated with thymic abnormalities presented as thymic tumors (~10%) or hyperplastic thymus (~65%). The exact role of thymus in Myasthenia Gravis development is not clear, yet many patients benefit from thymectomy. The apoptotic ligand TNF-Related Apoptosis-Inducing Ligand is thought to be involved in the regulation of thymocyte counts, although conflicting results are reported. We investigated differential expression profiles of TNF-Related Apoptosis-Inducing Ligand and its transmembrane receptors, Nuclear Factor-kB activation status, and apoptotic cell counts in healthy thymic tissue and pathological thymus from Myasthenia Gravis patients. All tissues expressed TNF-Related Apoptosis-Inducing Ligand and its receptors, with hyperplastic tissue having the highest expression levels of death receptors DR4 and DR5. No detectable Nuclear Factor-kB activation, at least via the canonical Protein Kinase A-mediated p65 Ser276 phosphorylation, was evident in any of the tissues studied. Apoptotic cell counts were higher in MG-associated tissue compared to the normal thymus. Possible use of the TNF-Related Apoptosis-Inducing Ligand within the concept of an apoptotic ligand-mediated medical thymectomy in thymoma- or thymic hyperplasia-associated Myasthenia Gravis is also discussed.

NF-Kβ Activation in U266 Cells on Mesenchymal Stem Cells

Purpose: Mesenchymal Stem Cells (MSCs) are one of the essential members of Bone Marrow (BM) microenvironment and the cells affect normal and malignant cells in BM milieu. One of the most important hematological malignancies is Multiple Myeloma (MM). Numerous studies reported various effects of MSCs on myeloma cells. MSCs initiate various signaling pathways in myeloma cells, particularly NF-kβ. NF-kβ signaling pathway plays pivotal role in the survival, proliferation and resistance of myeloma cells to the anticancer drugs, therefore this pathway can be said to be a vital target for cancer therapy. This study examined the relationship between U266 cells and MSCs. Methods: U266 cells were cultured with Umbilical Cord Blood derived-MSCs (UCB-MSCs) and Conditioned Medium (C.M). Effect of UCB-MSCs and C.M on proliferation rate and CD54 expression of U266 cells were examined with MTT assay and Flowcytometry respectively. Furthermore, expression of CXCL1, PECAM-1, JUNB, CCL2, CD44, CCL4, IL-6, and IL-8 were analyzed by Real Time-PCR (RT-PCR). Moreover, status of p65 protein in NF-kβ pathway assessed by western blotting. Results: Our findings confirm that UCB-MSCs support U266 cells proliferation and they increase CD54 expression. In addition, we demonstrate that UCB-MSCs alter the expression of CCL4, IL-6, IL-8, CXCL1 and the levels of phosphorylated p65 in U266 cells. Conclusion: Our study provides a novel sight to the role of MSCs in the activation of NF-kβ signaling pathway. So, NF-kβ signaling pathway will be targeted in future therapies against MM.

Non-canonical NFκB mutations reinforce pro-survival TNF response in multiple myeloma through an autoregulatory RelB:p50 NFκB pathway

Environmental drug resistance constitutes a serious impediment for therapeutic intervention in multiple myeloma. Tumor-promoting cytokines, such as tumor necrosis factor (TNF), induce nuclear factor-κB (NFκB)- driven expression of pro-survival factors, which confer resistance in myeloma cells to apoptotic insults from TNF-related apoptosis-inducing ligand (TRAIL) and other chemotherapeutic drugs. It is thought that RelA:p50 dimer, activated from IκBα-inhibited complex in response to TNF-induced canonical NFκB signal, mediates the pro-survival NFκB function in cancerous cells. Myeloma cells additionally acquire gain-of-function mutations in the non-canonical NFκB module, which induces partial proteolysis of p100 into p52 to promote RelB:p52/NFκB activation from p100-inhibited complex during immune cell differentiation. However, role of non-canonical NFκB signaling in the drug resistance in multiple myeloma remains unclear. Here we report that myeloma-associated non-canonical aberrations reinforce pro-survival TNF signaling in producing a protracted TRAIL-refractory state. These mutations did not act through a typical p52 NFκB complex, but completely degraded p100 to reposition RelB under IκBα control, whose degradation during TNF signaling induced an early RelB:p50 containing NFκB activity. More so, autoregulatory RelB synthesis prolonged this TNF-induced RelB:p50 activity in myeloma cells harboring non-canonical mutations. Intriguingly, TNF-activated RelB:p50 dimer was both necessary and sufficient, and RelA was not required, for NFκB-dependent pro-survival gene expressions and suppression of apoptosis. Indeed, high RelB mRNA expressions in myeloma patients correlated with the augmented level of pro-survival factors and resistance to therapeutic intervention. In sum, we provide evidence that cancer-associated mutations perpetuate TNF-induced pro-survival NFκB activity through autoregulatory RelB control and thereby exacerbate environmental drug resistance in multiple myeloma.

Oral ixazomib maintenance therapy in multiple myeloma

Continuous therapy has proven to be an effective therapeutic strategy to improve the outcome of both young and elderly multiple myeloma patients. Remarkably, lenalidomide and bortezomib showed to play a crucial role in this setting due to their safety profile allowing long-term exposure. Ixazomib, the first oral proteasome inhibitor to be evaluated in multiple myeloma, exerts substantial anti-myeloma activity as a single agent and particularly in combination with immunomodulatory drugs and it may be an attractive option for maintenance therapy. Here we address the issue of maintenance therapy as part of a therapeutic approach of multiple myeloma patients focusing on the potential role of ixazomib.

Future therapeutic options for patients with Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare lymphoma characterized by the accumulation of IgM-producing lymphoplasmacytic cells. Although WM patients can experience prolonged remissions, the disease invariably recurs. Therefore, novel treatments associated with higher success rates and lower toxicity profiles are needed. The discovery of recurrent mutations in the MYD88 and CXCR4 genes has unraveled potential therapeutic targets in WM patients. As a result of these findings and based on the design and execution of a prospective clinical trial, the FDA granted approval to ibrutinib, an oral Bruton tyrosine kinase (BTK) inhibitor, to treat patients with symptomatic WM. The present review focuses on potential therapies that could change the landscape of treatment of patients with WM, specifically focusing on inhibitors or antagonists or the proteasome, BTK, CD38, BCL2 and the CXCR4 and MYD88 genes themselves. Novel agents with novel mechanisms of action should be evaluated in the context of carefully designed clinical trials.

NF-κB dysregulation in multiple myeloma

The nuclear factor-κB (NF-κB) transcription factor family plays critical roles in the pathophysiology of hematologic neoplasias, including multiple myeloma. The current review examines the roles that this transcription factor system plays in multiple myeloma cells and the nonmalignant accessory cells of the local microenvironment; as well as the evidence indicating that a large proportion of myeloma patients harbor genomic lesions which perturb diverse genes regulating the activity of NF-κB. This article also discusses the therapeutic targeting of the NF-κB pathway using proteasome inhibitors, a pharmacological class that has become a cornerstone in the therapeutic management of myeloma; and reviews some of the future challenges and opportunities for NF-κB-related research in myeloma.

A dominant-negative F-box deleted mutant of E3 ubiquitin ligase, β-TrCP1/FWD1, markedly reduces myeloma cell growth and survival in mice

Treatment of multiple myeloma with bortezomib can result in severe adverse effects, necessitating the development of targeted inhibitors of the proteasome. We show that stable expression of a dominant-negative F-box deleted (ΔF) mutant of the E3 ubiquitin ligase, SCF^β-TrCP/FWD1, in murine 5TGM1 myeloma cells dramatically attenuated their skeletal engraftment and survival when inoculated into immunocompetent C57BL/KaLwRij mice. Similar results were obtained in immunodeficient bg-nu-xid mice, suggesting that the observed effects were independent of host recipient immune status. Bone marrow stroma offered no protection for 5TGM1-ΔF cells in cocultures treated with tumor necrosis factor (TNF), indicating a cell-autonomous anti-myeloma effect. Levels of p100, IκBα, Mcl-1, ATF4, total and cleaved caspase-3, and phospho-β-catenin were elevated in 5TGM1-ΔF cells whereas cIAP was down-regulated. TNF also activated caspase-3 and downregulated Bcl-2, correlating with the enhanced susceptibility of 5TGM1-ΔF cells to apoptosis. Treatment of 5TGM1 tumor-bearing mice with a β-TrCP1/FWD1 inhibitor, pyrrolidine dithiocarbamate (PDTC), significantly reduced tumor burden in bone. PDTC also increased levels of cleaved Mcl-1 and caspase-3 in U266 human myeloma cells, correlating with our murine data and validating the development of specific β-TrCP inhibitors as an alternative therapy to nonspecific proteasome inhibitors for myeloma patients.

Thymoquinone inhibits growth of human medulloblastoma cells by inducing oxidative stress and caspase-dependent apoptosis while suppressing NF-κB signaling and IL-8 expression

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. The transcription factor NF-κB is overexpressed in human MB and is a critical factor for MB tumor growth. NF-κB is known to regulate the expression of interleukin-8 (IL-8), the chemokine that enhances cancer cell growth and resistance to chemotherapy. We have recently shown that thymoquinone (TQ) suppresses growth of hepatocellular carcinoma cells in part by inhibiting NF-κB signaling. Here we sought to extend these studies in MB cells and show that TQ suppresses growth of MB cells in a dose- and time-dependent manner, causes G2M cell cycle arrest, and induces apoptosis. TQ significantly increased generation of reactive oxygen species (ROS), while pretreatment of MB cells with the ROS scavenger N-acetylcysteine (NAC) abrogated TQ-induced cell death and apoptosis, suggesting that TQ-induced cell death and apoptosis are oxidative stress-mediated. TQ inhibitory effects were associated with inhibition of NF-κB and altered expression of its downstream effectors IL-8 and its receptors, the anti-apoptotic Bcl-2, Bcl-xL, X-IAP, and FLIP, as well as the pro-apoptotic TRAIL-R1, caspase-8, caspase-9, Bcl-xS, and cytochrome c. TQ-triggered apoptosis was substantiated by up-regulation of the executioner caspase-3 and caspase-7, as well as cleavage of the death substrate poly(ADP-ribose)polymerase. Interestingly, pretreatment of MB cells with NAC or the pan-caspase inhibitor zVAD-fmk abrogated TQ-induced apoptosis, loss of cyclin B1 and NF-κB activity, suggesting that these TQ-mediated effects are oxidative stress- and caspase-dependent. These findings reveal that TQ induces both extrinsic and intrinsic pathways of apoptosis in MB cells, and suggest its potential usefulness in the treatment of MB.

AMPK Regulation of Cell Growth, Apoptosis, Autophagy, and Bioenergetics

In eukaryotic cells, AMP-activated protein kinase (AMPK) generally promotes catabolic pathways that produce ATP and at the same time inhibits anabolic pathways involved in different processes that consume ATP. As an energy sensor, AMPK is involved in the main cellular functions implicated in cell fate, such as cell growth and autophagy.Recently, AMPK has been connected with apoptosis regulation, although the molecular mechanism by which AMPK induces and/or inhibits cell death is not clear.This chapter reviews the essential role of AMPK in signaling pathways that respond to cellular stress and damage, highlighting the complex and reciprocal regulation between AMPK and their targets and effectors. The therapeutic implications of the role of AMPK in different pathologies such as diabetes, cancer, or mitochondrial dysfunctions are still controversial, and it is necessary to further investigate the molecular mechanisms underlying AMPK activation.

PAX5 interacts with RIP2 to promote NF-κB activation and drug-resistance of B-lymphoproliferative disorders

Paired box protein 5 (PAX5) plays a lineage determination role in B-cell development. However, high expression of PAX5 has been also found in various malignant diseases including B-lymphoproliferative disorders (B-LPDs), but its functions and mechanisms in these diseases are still unclear. Here, we show that PAX5 induces drug-resistance through association and activation of receptor-interacting serine/threonine-protein kinase2 (RIP2) and subsequent activation of NF-κB signaling and anti-apoptosis genes expression in B-lymphoproliferative cells. Furthermore, PAX5 is able to interact with RIP1-3, modulating both RIP1- mediated TNFR and RIP2-mediated NOD1 and NOD2 pathways. Our findings describe a novel function of PAX5 in regulating RIP1 and RIP2 activation, which is at least involved in chemo drug-resistance in B-LPDs.

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.

The use of novel agents in multiple myeloma patients with hepatic impairment

Novel drugs such as immunomodulators and proteasome inhibitors have improved the survival of patients with multiple myeloma. Like all therapeutic agents, appropriate dosing based on metabolism and clearance is important to maintain efficacy while avoiding toxicity. Hepatic impairment (HI) in multiple myeloma patients is rare but well described either due to disease or therapy-related factors. However, limited data are available on the appropriate use and dosing of the novel agent therapeutics in myeloma patients with HI. Furthermore, data on HI secondary to the novel agent toxicity are also sparse. This systematic review highlights the evidence on the use of novel agents like thalidomide, lenalidomide, pomalidomide, bortezomib and carfilzomib in patients with HI as well as their associated hepatic toxicities.

Preclinical efficacy of sepantronium bromide (YM155) in multiple myeloma is conferred by down regulation of Mcl-1

The inhibitor-of-apoptosis family member survivin has been reported to inhibit apoptosis and regulate mitosis and cytokinesis. In multiple myeloma, survivin has been described to be involved in downstream sequelae of various therapeutic agents. We assessed 1093 samples from previously untreated patients, including two independent cohorts of 392 and 701 patients, respectively. Survivin expression was associated with cell proliferation, adverse prognostic markers, and inferior event-free and overall survival, supporting the evaluation of survivin as a therapeutic target in myeloma. The small molecule suppressant of survivin - YM155 - is in clinical development for the treatment of solid tumors. YM155 potently inhibited proliferation and induced apoptosis in primary myeloma cells and cell lines. Gene expression and protein profiling revealed the critical roles of IL6/STAT3-signaling and the unfolded protein response in the efficacy of YM155. Both pathways converged to down regulate anti-apoptotic Mcl-1 in myeloma cells. Conversely, growth inhibition and apoptotic cell death by YM155 was rescued by ectopic expression of Mcl-1 but not survivin, identifying Mcl-1 as the pivotal downstream target of YM155 in multiple myeloma. Mcl-1 expression was likewise associated with adverse prognostic markers, and inferior survival. Our results strongly support the clinical evaluation of YM155 in patients with multiple myeloma.

Ixazomib for the treatment of multiple myeloma

INTRODUCTION

Proteasome inhibition is a mainstay in the treatment of multiple myeloma (MM). Bortezomib, the first proteasome inhibitor (PI) approved for MM therapy, has shown efficacy in relapsed/refractory patients and in the front-line setting. Among second-generation PIs, MLN9708 ( ixazomib ) is the first oral compound to be evaluated in MM treatment and has shown improvement in pharmacokinetic and pharmacodynamic parameters compared with bortezomib with a similar efficacy in the control of myeloma growth and in the prevention of bone loss.

AREAS COVERED

In this review, the authors discuss the rationale for use of PIs. They then summarize the clinical development of ixazomib in MM, from initial Phase I to Phase II studies as a monotherapy and in combination with other chemotherapeutics.

EXPERT OPINION

Preliminary data of Phase I/II trials showed that ixazomib had a good safety profile and exerted anti-myeloma activity as a single agent in relapsed/refractory patients. Furthermore, ixazomib also had efficacy in patients who were refractory to bortezomib. Its use in combination with lenalidomide and dexamethasone was shown to be an effective and well-tolerated regimen in up-front treatment leading to minimal residual disease negativity in a significant number of patients. Results of Phase III trials, evaluating ixazomib in induction or maintenance therapy, are awaited.

Inhibition of thioredoxin 1 leads to apoptosis in drug-resistant multiple myeloma

Multiple myeloma (MM) is a hematological malignancy characterized by the aberrant accumulation of clonal plasma cells in the bone marrow. Despite recent advancement in anti-myeloma treatment, MM remains an incurable disease. This study showed higher intrinsic oxidative stress and higher Trx1 and TrxR1 protein levels in MM cells compared to normal cells. Drug-induced Trx1 (PX-12) and TrxR1 (Auranofin) inhibition disrupted redox homeostasis resulting in ROS-induced apoptosis in MM cells and a reduction in clonogenic activity. Knockdown of either Trx1 or TrxR1 reduced MM cell viability. Trx1 inhibition by PX-12 sensitized MM cells to undergo apoptosis in response to the NF-κβ inhibitors, BAY 11-7082 and curcumin. PX-12 treatment decreased the expression of the NF-κβ subunit p65 in MM cells. Bortezomib-resistant MM cells contained higher Trx1 protein levels compared to the parental cells and PX-12 treatment resulted in apoptosis. Thus, increased Trx1 enhances MM cell growth and survival and exerts resistance to NF-κβ inhibitors. Therefore inhibiting the thioredoxin system may be an effective therapeutic strategy to treat newly diagnosed as well as relapsed/refractory MM.

Increasing progranulin levels and blockade of the ERK1/2 pathway: upstream and downstream strategies for the treatment of progranulin deficient frontotemporal dementia

Frontotemporal lobar degeneration (FTLD) is a neurodegenerative disorder marked by mild-life onset and progressive changes in behavior, social cognition, and language. Loss-of-function progranulin gene (GRN) mutations are the major cause of FTLD with TDP-43 protein inclusions (FTLD-TDP). Disease-modifying treatments for FTLD-TDP are not available yet. Mounting evidence indicates that cell cycle dysfunction may play a pathogenic role in neurodegenerative disorders including FTLD. Since cell cycle re-entry of posmitotic neurons seems to precede neuronal death, it was hypothesized that strategies aimed at preventing cell cycle progression would have neuroprotective effects. Recent research in our laboratory revealed cell cycle alterations in lymphoblasts from FTLD-TDP patients carrying a null GRN mutation, and in PGRN deficient SH-SY5Y neuroblastoma cells, involving overactivation of the ERK1/2 signaling pathway. In this work, we have investigated the effects of PGRN enhancers drugs and ERK1/2 inhibitors, in these cellular models of PGRN-deficient FTLD. We report here that both restoring the PGRN content, by suberoylanilide hydroxamic acid (SAHA) or chloroquine (CQ), as blocking ERK1/2 activation by selumetinib (AZD6244) or MEK162 (ARRY-162), normalized the CDK6/pRb pathway and the proliferative activity of PGRN deficient cells. Moreover, we found that SAHA and selumetinib prevented the cytosolic TDP-43 accumulation in PGRN-deficient lymphoblasts. Considering that these drugs are able to cross the blood-brain barrier, and assuming that the alterations in cell cycle and signaling observed in lymphoblasts from FTLD patients could be peripheral signs of the disease, our results suggest that these treatments may serve as novel therapeutic drugs for FTLD associated to GRN mutations.

Bone-Specific Alkaline Phosphatase Levels among Patients with Multiple Myeloma Receiving Various Therapy Options

OBJECTIVE

This study aimed to investigate the impact of the different therapy regimens used in multiple myeloma (MM) on bone-specific alkaline phosphatase (BALP) levels.

MATERIALS AND METHODS

One hundred and thirteen patients with MM were included in the study. Patients were grouped according to the regimens they received, as follows: group 1, melphalan and prednisolone (MP); group 2, vincristine, adriablastin, and dexamethasone (VAD); group 3, thalidomide plus dexamethasone; and group 4, bortezomib plus dexamethasone. BALP levels were measured before treatment and at the third and sixth months of treatment. A fifth group consisted of patients in the post-treatment remission period at study entry (no-treatment group).

RESULTS

The BALP levels at the third and sixth months of the treatment were significantly higher than the pre-treatment levels in the bortezomib and the no-treatment groups, whereas no significant difference was observed in the MP, VAD, and thalidomide groups.

CONCLUSION

Considering that BALP is a surrogate marker of bone formation, our study suggests that bortezomib more efficiently leads to the improvement of bone disease in myeloma than other treatment options.

Progranulin Deficiency Reduces CDK4/6/pRb Activation and Survival of Human Neuroblastoma SH-SY5Y Cells

Null mutations in GRN are associated with frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP). However, the influence of progranulin (PGRN) deficiency in neurodegeneration is largely unknown. In neuroblastoma cells, silencing of GRN gene causes significantly reduced cell survival after serum withdrawal. The following observations suggest that alterations of the CDK4/6/retinoblastoma protein (pRb) pathway, secondary to changes in PI3K/Akt and ERK1/2 activation induced by PGRN deficiency, are involved in the control of serum deprivation-induced apoptosis: (i) inhibiting CDK4/6 levels or their associated kinase activity by sodium butyrate or PD332991 sensitized control SH-SY5Y cells to serum deprivation-induced apoptosis without affecting survival of PGRN-deficient cells; (ii) CDK4/6/pRb seems to be downstream of the PI3K/Akt and ERK1/2 signaling pathways since their specific inhibitors, LY294002 and PD98059, were able to decrease CDK6-associated kinase activity and induce death of control SH-SY5Y cells; (iii) PGRN-deficient cells show reduced stimulation of PI3K/Akt, ERK1/2, and CDK4/6 activities compared with control cells in the absence of serum; and (iv) supplementation of recombinant human PGRN was able to rescue survival of PGRN-deficient cells. These observations highlight the important role of PGRN-mediated stimulation of the PI3K/Akt-ERK1/2/CDK4/6/pRb pathway in determining the cell fate survival/death under serum deprivation.