BCL2 Family Inhibitors in the Biology and Treatment of Multiple Myeloma

Toll-like receptor signaling in multiple myeloma cells promotes the expression of pro-survival genes B-cell lymphoma 2 and MYC and modulates the expression of B-cell maturation antigen

Infections are common in plasma cell cancer multiple myeloma (MM) due to disease-related immune deficiencies and cancer treatment. Myeloma cells express Toll-like receptors (TLRs), and TLR activation has been shown to induce proliferative and pro-survival signals in cancer cells. MM is a complex and heterogeneous disease, and expression levels of TLRs as well as downstream signaling components are likely to differ between patients. Here, we show that in a large cohort of patients, TLR1, TLR4, TLR6, TLR9, and TLR10 are the most highly expressed in primary CD138+ cells. Using an MM cell line expressing TLR4 and TLR9 as a model, we demonstrate that TLR4 and TLR9 activation promoted the expression of well-established pro-survival and oncogenes in MM such as MYC, IRF4, NFKB, and BCL2. TLR4 and TLR9 activation inhibited the efficacy of proteasome inhibitors bortezomib and carfilzomib, drugs used in the treatment of MM. Inhibiting the autophagosome-lysosome protein degradation pathway by hydroxychloroquine (HCQ) diminished the protective effect of TLR activation on proteasome inhibitor-induced cytotoxicity. We also found that TLR signaling downregulated the expression of TNFRSF17, the gene encoding for B-cell maturation antigen (BCMA). MYC, BCL2, and BCL2L1 were upregulated in approximately 50% of primary cells, while the response to TLR signaling in terms of TNFRSF17 expression was dichotomous, as an equal fraction of patients showed upregulation and downregulation of the gene. While proteasome inhibitors are part of first-line MM treatment, several of the new anti-MM immune therapeutic drugs target BCMA. Thus, TLR activation may render MM cells less responsive to commonly used anti-myeloma drugs.

Methylcrotonyl-CoA carboxylase subunit 1 (MCCA) regulates multidrug resistance in multiple myeloma

AIMS

This study aimed to investigate the effect and mechanism of methylcrotonyl-CoA carboxylase subunit 1 (MCCA) on multidrug resistance in multiple myeloma (MM).

MATERIALS AND METHODS

The apoptosis kit and CCK-8 reagent were used to detect drug-induced cell apoptosis and viability. Immunoprecipitation, immunofluorescence staining, and protein structural simulation were used to detect the interaction between MCCA and Bad. Immunodeficient mice were injected with ARD cells and treated with bortezomib. Changes in tumor burden were recorded by bioluminescence imaging, and κ light chain content in the blood of mice was detected by enzyme-linked immunoassay.

KEY FINDINGS

Patients with high MCCA expression from a primary MM dataset had superior overall survival. After treatment with different anti-MM drugs, MCCA knockdown MM (MCCA-KD) cells had higher survival rates than control knockdown (CTR-KD) cells (p < 0.05). Mechanistic studies have revealed that MCCA-KD cells had dysfunctional mitochondria with decreased Bax and Bad levels and increased Bcl-xl and Mcl-1 levels. Furthermore, that MCCA and Bad demonstrated protein-protein interactions. The half-life of Bad in MCCA-KD cells is significantly shorter than that in CTR-KD cells (7.34 vs. 2.42 h, p < 0.05). In a human MM xenograft mouse model, we confirmed that MCCA-KD tumors had a poor response to anti-MM drugs in vivo. Finally, we showed that MCCA might contribute to multidrug resistance in different human cancers, particularly in solid tumors.

SIGNIFICANCE

Our findings demonstrated a novel function of MCCA in multidrug resistance. The lack of MCCA expression promoted antiapoptotic cell signaling in MM cells.

Cancer Resistance Is Mediated by the Upregulation of Several Anti-Apoptotic Gene Products via the Inducible Nitric Oxide Synthase/Nitric Oxide Pathway: Therapeutic Implications

Significance: Several therapeutic strategies for cancer treatments have been developed with time, and significant milestones have been achieved recently. However, with these novel therapies, not all cancer types respond and in the responding cancer types only a subset is affected. The failure to respond is principally the result that these cancers develop several mechanisms of resistance. Thus, a focus of current research investigations is to unravel the various mechanisms that regulate resistance and identify suitable targets for new therapeutics. Recent Advances: Hence, many human cancer types have been reported to overexpress the inducible nitric oxide synthase (iNOS) and it has been suggested that iNOS/nitric oxide (NO) plays a pivotal role in the regulation of resistance. We have postulated that iNOS overexpression or NO regulates the overexpression of pivotal anti-apoptotic gene products such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma extra large (Bcl-xL), myeloid cell leukemia-1 (Mcl-1), and survivin. In this report, we describe the various mechanisms, transcriptional, post-transcriptional, and post-translational, by which iNOS/NO regulates the expression of the above anti-apoptotic gene products. Critical Issues: The iNOS/NO-mediated regulation of the four gene products is not the same with both specific and overlapping pathways. Our findings are, in large part, validated by bioinformatic analyses demonstrating, in several cancers, several direct correlations between the expression of iNOS and each of the four examined anti-apoptotic gene products. Future Directions: We have proposed that targeting iNOS may be highly efficient since it will result in the underexpression of multiple anti-apoptotic proteins and shifting the balance toward the proapoptotic gene products and reversal of resistance. Antioxid. Redox Signal. 39, 853-889.

Simultaneously Targeting Two Coupled Signalling Molecules in the Mesenchymal Stem Cell Support Efficiently Sensitises the Multiple Myeloma Cell Line H929 to Bortezomib

Several studies have shown that diverse components of the bone marrow (BM) microenvironment play a central role in the progression, pathophysiology, and drug resistance in multiple myeloma (MM). In particular, the dynamic interaction between BM mesenchymal stem cells (BM-MSC) and MM cells has shown great relevance. Here we showed that inhibiting both PKC and NF-κB signalling pathways in BM-MSC reduced cell survival in the MM cell line H929 and increased its susceptibility to the proteasome inhibitor bortezomib. PKC-mediated cell survival inhibition and bortezomib susceptibility induction were better performed by the chimeric peptide HKPS than by the classical enzastaurin inhibitor, probably due to its greatest ability to inhibit cell adhesion and its increased capability to counteract the NF-κB-related signalling molecules increased by the co-cultivation of BM-MSC with H929 cells. Thus, inhibiting two coupled signalling molecules in BM-MSC was more effective in blocking the supportive cues emerging from the mesenchymal stroma. Considering that H929 cells were also directly susceptible to PKC and NF-κB inhibition, we showed that treatment of co-cultures with the HKPS peptide and BAY11-7082, followed by bortezomib, increased H929 cell death. Therefore, targeting simultaneously connected signalling elements of BM-MSC responsible for MM cells support with compounds that also have anti-MM activity can be an improved treatment strategy.

Management of Relapsed-Refractory Multiple Myeloma in the Era of Advanced Therapies: Evidence-Based Recommendations for Routine Clinical Practice

Multiple myeloma (MM) is the second most common hematologic malignancy in adults worldwide. Over the past few years, major therapeutic advances have improved progression-free and overall survival, as well as quality of life. Despite this recent progress, MM remains incurable in the vast majority of cases. Patients eventually relapse and become refractory to multiple drug classes, making long-term management challenging. In this review, we will focus on the treatment paradigm of relapsed/refractory MM (RRMM) in the era of advanced therapies emphasizing the available novel modalities that have recently been incorporated into routine practice, such as chimeric antigen receptor T-cell therapy, bispecific antibodies, and other promising approaches. We will also discuss major factors that influence the selection of appropriate drug combinations or cellular therapies, such as relapse characteristics, and other disease and patient related parameters. Our goal is to provide insight into the currently available and experimental therapies for RRMM in an effort to guide the therapeutic decision-making process.

AL amyloidosis clonal plasma cells are regulated by microRNAs and dependent on anti-apoptotic BCL2 family members

BACKGROUND

Noncoding RNAs such as microRNAs (miRNAs) have attracted attention as biological pathway regulators, which differ from chromosomal translocations and gene point mutations. Their involvement in the molecular mechanisms underlying light chain (AL) amyloidosis pathogenesis is yet to be elucidated.

AIMS

To decipher specific miRNA expression profile in AL-amyloidosis and to examine how miRNAs are involved in AL pathogenesis.

METHODS

The expression profile of miRNAs and mRNA from bone marrow (BM)-derived CD138+ cells were determined using the NanoString nCounter assay and RNA-Seq, respectively. The effect of aberrantly expressed miRNAs on potential molecular targets was analyzed by qRT-PCR, Western blot, Mito-potential assay, and Annexin-PI staining.

RESULTS

Genes which were significantly differentially expressed between AL-amyloidosis and MM, were found to be involved in cell growth and apoptotic mechanisms. Specifically, BCL2L1, MCL1, and BCL2 were upregulated in AL-amyloidosis compared with MM and controls. The levels of miR-181a-5p and miR-9-5p, which regulate the above-mentioned genes, were lower in BM samples from AL-amyloidosis compared with controls, providing a mechanism for BCL2 family gene upregulation. When miR-9-5p and miR-181a-5p were overexpressed in ALMC1 cells, BCL2L1, MCL1, and BCL2 were downregulated and induced apoptosis. Treatment of ALMC-1 cells with venetoclax, (BCL-2 inhibitor), resulted in the upregulation of those miRNAs, the downregulation of BCL2, MCL1, and BCL2L1 mRNA and protein levels, and subsequent apoptosis.

CONCLUSION

Our findings suggest that miR-9-5p and miR-181a-5p act as tumor-suppressors whose downregulation induces anti-apoptotic mechanisms underlying the pathogenesis of AL-amyloidosis. The study highlights the post-transcriptional regulation in AL-amyloidosis and provides pathogenetic evidence for the potential use of BCL-2 inhibitors in this disease.

Guidelines for non-transplant chemotherapy for treatment of systemic AL amyloidosis: EHA-ISA working group

BACKGROUND

This guideline has been developed jointly by the European Society of Haematology and International Society of Amyloidosis recommending non-transplant chemotherapy treatment for patients with AL amyloidosis.

METHODS

A review of literature and grading of evidence as well as expert recommendations by the ESH and ISA guideline committees.

RESULTS AND CONCLUSIONS

The recommendations of this committee suggest that treatment follows the clinical presentation which determines treatment tolerance tempered by potential side effects to select and modify use of drugs in AL amyloidosis. All patients with AL amyloidosis should be considered for clinical trials where available. Daratumumab-VCD is recommended from most untreated patients (VCD or VMDex if daratumumab is unavailable). At relapse, the two guiding principles are the depth and duration of initial response, use of a class of agents not previously exposed as well as the limitation imposed by patients' fitness/frailty and end organ damage. Targeted agents like venetoclax need urgent prospective evaluation. Future prospective trials should include advanced stage patients to allow for evidence-based treatment decisions. Therapies targeting amyloid fibrils or those reducing the proteotoxicity of amyloidogenic light chains/oligomers are urgently needed.

Bcl-xL activity influences outcome of the mitotic arrest

Microtubule-targeting (MT) drugs taxanes and vinca alkaloids are widely used as chemotherapeutic agents against different tumors for more than 30 years because of their ability to block mitotic progression by disrupting the mitotic spindle and activating the spindle assembly checkpoint (SAC) for a prolonged period of time. However, responses to mitotic arrest are different—some cells die during mitotic arrest, whereas others undergo mitotic slippage and survive becoming able for proliferation. Using normal fibroblasts and several cancer cell types we determined two critical doses, T1 and T2, of mitotic inhibitors (nocodazole, Taxol, and vinorelbine). T1 is the maximal dose cells can tolerate undergoing normal division, and T2 is the minimal mitostatic dose, wherein &gt; 90% of mitotic cells are arrested in mitosis. In all studied cell lines after treatment with mitotic inhibitors in a dose above T2 cells had entered mitosis either die or undergo mitotic slippage. We show that for all three drugs used cell death during mitotic arrest and after slippage proceeded via mitochondria-dependent apoptosis. We determined two types of cancer cells: sensitive to mitotic arrest, that is, undergoing death in mitosis (DiM) frequently, and resistant to mitotic arrest, that is, undergoing mitotic slippage followed by prolonged survival. We then determined that inhibition of Bcl-xL, but not other anti-apoptotic proteins of the Bcl-2 group that regulate MOMP, make resistant cells susceptible to DiM induced by mitotic inhibitors. Combined treatment with MT drugs and highly specific Bcl-xL inhibitors A-1155643 or A-1331852 allows achieving 100% DiM in a time significantly shorter than maximal duration of mitotic arrest in all types of cultured cells tested. We further examined efficacy of sequential treatment of cultured cells using mitotic inhibitors followed by inhibitors of Bcl-xL anti-apoptotic protein and for the first time show that sensitivity to Bcl-xL inhibitors rapidly declines after mitotic slippage. Thus sequential use of mitotic inhibitors and inhibitors of Bcl-xL anti-apoptotic protein will be efficient only if the Bcl-xL inhibitor will be added before mitotic slippage occurs or soon afterward. The combined treatment proposed might be an efficient approach to anti-cancer therapy.

Exploring the current molecular landscape and management of multiple myeloma patients with the t(11;14) translocation

Multiple myeloma (MM) is a genetically complex disease. The key myeloma-initiating genetic events are hyperdiploidy and translocations involving the immunoglobulin heavy chain (IgH) enhancer on chromosome 14, which leads to the activation of oncogenes (e.g., CCND1, CCND3, MAF, and MMSET). The t(11;14) translocation is the most common in MM (15%–20%) and results in cyclin D1 (CCND1) upregulation, which leads to kinase activation and tumor cell proliferation. Notably, t(11;14) occurs at a higher rate in patients with plasma cell leukemia (40%) and light chain amyloidosis (50%). Patients with myeloma who harbor the t(11;14) translocation have high levels of the anti-apoptotic protein B-cell lymphoma 2 (BCL2). Multiple studies demonstrated that the presence of t(11;14) was predictive of BCL2 dependency, suggesting that BCL2 could be a target in this subtype of myeloma. Venetoclax, an oral BCL2 inhibitor, has shown remarkable activity in treating relapsed/refractory MM patients with t(11;14) and BCL2 overexpression, either as monotherapy or in combination with other anti-myeloma agents. In this review, we describe the molecular defects associated with the t(11;14), bring into question the standard cytogenetic risk of myeloma patients harboring t(11;14), summarize current efficacy and safety data of targeted venetoclax-based therapies, and discuss the future of individualized or precision medicine for this unique myeloma subgroup, which will guide optimal treatment.

Gene expression profiling and in vitro functional studies reveal RAD54L as a potential therapeutic target in multiple myeloma

Background

Current advances in the molecular biology of multiple myeloma (MM) are not sufficient to fully delineate the genesis and development of this disease.

Objective

This study aimed to identify molecular targets underlying MM pathogenesis.

Methods

mRNA expression profiling for 29 samples (19 MM samples, 7 MM cell lines and 3 controls) were obtained using microarray. We evaluated the in vitro effects of RAD54L gene silencing on the proliferation, apoptosis and cell cycle distribution in KMS-28BM human MM cells using siRNA approach. Cell proliferation was determined by MTS assay while apoptosis and cell cycle distribution were analysed with flow cytometry. Gene and protein expression was evaluated using RT-qPCR and ELISA, respectively.

Results

Microarray results revealed a total of 5124 differentially expressed genes (DEGs), in which 2696 and 2428 genes were up-regulated and down-regulated in MM compared to the normal controls, respectively (fold change ≥ 2.0; P < 0.05). Up-regulated genes (RAD54L, DIAPH3, SHCBP1, SKA3 and ANLN) and down-regulated genes (HKDC1, RASGRF2, CYSLTR2) have never been reported in association with MM. Up-regulation of RAD54L was further verified by RT-qPCR (P < 0.001). In vitro functional studies revealed that RAD54L gene silencing significantly induced growth inhibition, apoptosis (small changes) and cell cycle arrest in G0/G1 phase in KMS-28BM (P < 0.05). Silencing of RAD54L also decreased its protein level (P < 0.05).

Conclusions

This study has identified possible molecular targets underlying the pathogenesis of MM. For the first time, we reveal RAD54L as a potential therapeutic target in MM, possibly functioning in the cell cycle and checkpoint control.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13258-022-01272-7.

Transcriptomic Analysis in Multiple Myeloma and Primary Plasma Cell Leukemia with t(11;14) Reveals Different Expression Patterns with Biological Implications in Venetoclax Sensitivity

Simple Summary

The growing interest in BCL2 inhibitors for the treatment of multiple myeloma (MM) has led to the need for biomarkers that are able to predict patient’s sensitivity to the drug. The presence of the chromosomal translocation t(11;14) in MM is mainly associated with sensitivity to venetoclax and good prognosis. The incidence of t(11;14) largely increases in primary Plasma Cell Leukemia (pPCL) in association with an unfavorable outcome. Currently, data concerning pPCL sensitivity to venetoclax are virtually absent. In this context, we investigated the transcriptome of MM and pPCL with t(11;14), evidencing that the two clinical entities are likely responsive to venetoclax based on different molecular programs, thus prompting further studies to elucidate better novel potential predictive biomarkers.

Abstract

Mechanisms underlying the pathophysiology of primary Plasma Cell Leukemia (pPCL) and intramedullary multiple myeloma (MM) need to be further elucidated, being potentially relevant for improving therapeutic approaches. In such a context, the MM and pPCL subgroups characterized by t(11;14) deserve a focused investigation, as the presence of the translocation is mainly associated with sensitivity to venetoclax. Herein, we investigated a proprietary cohort of MM and pPCL patients, focusing on the transcriptional signature of samples carrying t(11;14), whose incidence increases in pPCL in association with an unfavorable outcome. In addition, we evaluated the expression levels of the BCL2-gene family members and of a panel of B-cell genes recently reported to be associated with sensitivity to venetoclax in MM. Moreover, transcriptional analysis of lncRNAs in the two clinical settings led to the identification of several differentially expressed transcripts, among which the SNGH6 deregulated lncRNA might be relevant in the pathogenesis and prognosis of pPCL with t(11;14). Overall, our data suggest that MMs and pPCLs with t(11;14) might be responsive to venetoclax based on different molecular programs, prompting further studies to elucidate better novel potential predictive biomarkers.

Role of 1q21 in Multiple Myeloma: From Pathogenesis to Possible Therapeutic Targets

Multiple myeloma (MM) is characterized by an accumulation of malignant plasma cells (PCs) in the bone marrow (BM). The amplification of 1q21 is one of the most common cytogenetic abnormalities occurring in around 40% of de novo patients and 70% of relapsed/refractory MM. Patients with this unfavorable cytogenetic abnormality are considered to be high risk with a poor response to standard therapies. The gene(s) driving amplification of the 1q21 amplicon has not been fully studied. A number of clear candidates are under investigation, and some of them (IL6R, ILF2, MCL-1, CKS1B and BCL9) have been recently proposed to be potential drivers of this region. However, much remains to be learned about the biology of the genes driving the disease progression in MM patients with 1q21 amp. Understanding the mechanisms of these genes is important for the development of effective targeted therapeutic approaches to treat these patients for whom effective therapies are currently lacking. In this paper, we review the current knowledge about the pathological features, the mechanism of 1q21 amplification, and the signal pathway of the most relevant candidate genes that have been suggested as possible therapeutic targets for the 1q21 amplicon.