Epigenetics in Multiple Myeloma

The Genetic and Molecular Drivers of Multiple Myeloma: Current Insights, Clinical Implications, and the Path Forward

Background

Multiple myeloma (MM) is a hematological malignancy characterized by the clonal proliferation of malignant plasma cells within the bone marrow. The disease's complexity is underpinned by a variety of genetic and molecular abnormalities that drive its progression.

Methods

This review was conducted through a state-of-The-art literature search, primarily utilizing PubMed to gather peer-reviewed articles. We focused on the most comprehensive and cited studies to ensure a thorough understanding of the genetic and molecular landscapes of MM.

Results

We detail primary and secondary alterations such as translocations, hyperdiploidy, single nucleotide variants (SNVs), copy number alterations (CNAs), gene fusions, epigenetic modifications, non-coding RNAs, germline predisposing variants, and the influence of the tumor microenvironment (TME). Our analysis highlights the heterogeneity of MM and the challenges it poses in treatment and prognosis, emphasizing the distinction between driver mutations, which actively contribute to oncogenesis, and passenger mutations, which arise due to genomic instability and do not contribute to disease progression.

Conclusion & Future Perspectives

We report key controversies and challenges in defining the genetic drivers of MM, and examine their implications for future therapeutic strategies. We discuss the importance of systems biology approaches in understanding the dependencies and interactions among these alterations, particularly highlighting the impact of double and triple-hit scenarios on disease outcomes. By advancing our understanding of the molecular drivers and their interactions, this review sets the stage for novel therapeutic targets and strategies, ultimately aiming to improve clinical outcomes in MM patients.

Identification of MicroRNAs With In Vivo Efficacy in Multiple Myeloma-related Xenograft Models

BACKGROUND/AIM

Multiple myeloma is a B-cell neoplasm, which can spread within the marrow of the bones forming many small tumors. In advanced disease, multiple myeloma can spread to the blood as plasma cell leukemia. In some cases, a localized tumor known as plasmacytoma is found within a single bone. Despite the approval of several agents such as melphalan, corticosteroids, proteasome inhibitors, thalidomide-based immuno-modulatory agents, histone deacetylase inhibitors, a nuclear export inhibitor and monoclonal antibodies daratuzumab and elatuzumab, the disease presently remains uncurable.

MATERIALS AND METHODS

In order to define new targets and treatment modalities we searched the literature for microRNAs, which increase or inhibit in vivo efficacy in multiple-myeloma-related xenograft models.

RESULTS AND CONCLUSION

We identified six up-regulated and twelve down-regulated miRs, which deserve further preclinical validation.

Anti-VEGF Drugs in the Treatment of Multiple Myeloma Patients

The interaction between the bone marrow microenvironment and plasma cells plays an essential role in multiple myeloma progression and drug resistance. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway in vascular endothelial cells activates and promotes angiogenesis. Moreover, VEGF activates and promotes vasculogenesis and vasculogenic mimicry when it interacts with VEGF receptors expressed in precursor cells and inflammatory cells, respectively. In myeloma bone marrow, VEGF and VEGF receptor expression are upregulated and hyperactive in the stromal and tumor cells. It has been demonstrated that several antiangiogenic agents can effectively target VEGF-related pathways in the preclinical phase. However, they are not successful in treating multiple myeloma, probably due to the vicarious action of other cytokines and signaling pathways. Thus, the simultaneous blocking of multiple cytokine pathways, including the VEGF/VEGFR pathway, may represent a valid strategy to treat multiple myeloma. This review aims to summarize recent advances in understanding the role of the VEGF/VEGFR pathway in multiple myeloma, and mainly focuses on the transcription pathway and on strategies that target this pathway.

Promoter hypermethylation influences the suppressive role of long non-coding RNA MEG3 in the development of multiple myeloma

Methylation is a fundamental regulator of gene transcription. Long non-coding RNA maternally expressed 3 (MEG3) inhibits cell proliferation in various types of cancer. However, the molecular mechanisms of MEG3 methylation in the regulation of multiple myeloma (MM) are unknown. In the present study, MEG3 upregulation was negatively associated with the International Staging System (ISS) status of the bone marrow samples of 39 patients with MM. MEG3 overexpression in an MM cell line resulted in elevated p53 expression. Furthermore, the results of methylation-specific PCR revealed that the abnormal methylation status of the MEG3 promoter region was present in eight of the 39 bone marrow samples collected. Treatment of the MM cell line with the DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) resulted in tumor cell proliferation inhibition, apoptosis induction and G₀/G₁ cell cycle arrest. Furthermore, 5-Aza-CdR decreased aberrant hypermethylation of the MEG3 promoter and increased the expression of MEG3. However, 5-Aza-CdR exerted no effect on p53 expression. To the best of our knowledge, the present study is the first to report that the demethylation reagent 5-Aza-CdR may serve as a therapeutic agent in MM by upregulating MEG3 expression. However, the mechanism of action was independent of p53 expression.

Bone Marrow Stromal Cells-Induced Drug Resistance in Multiple Myeloma

Multiple myeloma is a B-cell lineage cancer in which neoplastic plasma cells expand in the bone marrow and pathophysiological interactions with components of microenvironment influence many biological aspects of the malignant phenotype, including apoptosis, survival, proliferation, and invasion. Despite the therapeutic progress achieved in the last two decades with the introduction of a more effective and safe new class of drugs (i.e., immunomodulators, proteasome inhibitors, monoclonal antibodies), there is improvement in patient survival, and multiple myeloma (MM) remains a non-curable disease. The bone marrow microenvironment is a complex structure composed of cells, extracellular matrix (ECM) proteins, and cytokines, in which tumor plasma cells home and expand. The role of the bone marrow (BM) microenvironment is fundamental during MM disease progression because modification induced by tumor plasma cells is crucial for composing a "permissive" environment that supports MM plasma cells proliferation, migration, survival, and drug resistance. The "activated phenotype" of the microenvironment of multiple myeloma is functional to plasma cell proliferation and spreading and to plasma cell drug resistance. Plasma cell drug resistance induced by bone marrow stromal cells is mediated by stress-managing pathways, autophagy, transcriptional rewiring, and non-coding RNAs dysregulation. These processes represent novel targets for the ever-increasing anti-MM therapeutic armamentarium.

Scriptaid inhibits cell survival, cell cycle, and promotes apoptosis in multiple myeloma via epigenetic regulation of p21

Multiple myeloma (MM) is an extremely serious plasma cell malignancy. Despite the recent introduction of chemotherapies such as bortezomib and lenalidomide, it remains an incurable disease due to the high rate of relapse and the development of drug resistance. Epigenetic regulation is closely related to MM progression, but the epigenetic modification mechanism of MM cell apoptosis has remained unclear. As a novel histone deacetylase inhibitor (HDACi), Scriptaid's possible roles in MM progression have not been explored. Herein, we found that Scriptaid decreased several human MM cell viabilities in a dose-dependent manner. Scriptaid was also able to dose dependently and significantly induce MM cell cycle arrest at the G₂/M phase. Moreover, Scriptaid facilitates p21 transcriptional activities by mediating H3Ac gene-activated modification, eventually leading to MM cell apoptosis. Overall, our results show that Scriptaid is an inducer of MM cell death, suggesting the possibility for Scriptaid-mediated therapeutics to cure refractory/relapsed MM.