Posttranslational modification of Aurora A-NSD2 loop contributes to drug resistance in t(4;14) multiple myeloma

Acquired Bortezomib Resistance in Multiple Myeloma: From Mechanisms to Strategy

OPINION STATEMENT

Multiple myeloma (MM) is a heterogeneous plasma cell tumor with a survival period of several months to over ten years. Despite the development of various new drugs, MM is still incurable and recurs repeatedly. Bortezomib, a landmark event in the history of MM treatment, has dramatically improved the prognosis of patients with MM. Although proteasome inhibitors (PIs) represented by bortezomib, have greatly prolonged MM survival, unfortunately, almost all MM will develop bortezomib resistance, leading to relapse with a shorter survival. It has been reported that both the tumor microenvironment and myeloma cells drive bortezomib resistance. Multiple treatment methods have been attempted to overcome bortezomib resistance, but unfortunately, there has been no breakthrough. It is believed that the key resistance mechanism has not yet been discovered. A deeper understanding of the mechanism of bortezomib resistance and strategies to overcome it can help identify key resistance mechanisms and further improve the prognosis of MM.

Histone lysine methylation modifiers controlled by protein stability

Histone lysine methylation is pivotal in shaping the epigenetic landscape and is linked to cell physiology. Coordination of the activities of multiple histone lysine methylation modifiers, namely, methyltransferases and demethylases, modulates chromatin structure and dynamically alters the epigenetic landscape, orchestrating almost all DNA-templated processes, such as transcription, DNA replication, and DNA repair. The stability of modifier proteins, which is regulated by protein degradation, is crucial for their activity. Here, we review the current knowledge of modifier-protein degradation via specific pathways and its subsequent impact on cell physiology through epigenetic changes. By summarizing the functional links between the aberrant stability of modifier proteins and human diseases and highlighting efforts to target protein stability for therapeutic purposes, we aim to promote interest in defining novel pathways that regulate the degradation of modifiers and ultimately increase the potential for the development of novel therapeutic strategies.

The significant others of aurora kinase a in cancer: combination is the key

AURKA is predominantly famous as an essential mitotic kinase. Recent findings have also established its critical role in a plethora of other biological processes including ciliogenesis, mitochondrial dynamics, neuronal outgrowth, DNA replication and cell cycle progression. AURKA overexpression in numerous cancers is strongly associated with poor prognosis and survival. Still no AURKA-targeted drug has been approved yet, partially because of the associated collateral toxicity and partly due to its limited efficacy as a single agent in a wide range of tumors. Mechanistically, AURKA overexpression allows it to phosphorylate numerous pathological substrates promoting highly aggressive oncogenic phenotypes. Our review examines the most recent advances in AURKA regulation and focuses on 33 such direct cancer-specific targets of AURKA and their associated oncogenic signaling cascades. One of the common themes that emerge is that AURKA is often involved in a feedback loop with its substrates, which could be the decisive factor causing its sustained upregulation and hyperactivation in cancer cells, an Achilles heel not exploited before. This dynamic interplay between AURKA and its substrates offers potential opportunities for targeted therapeutic interventions. By targeting these substrates, it may be possible to disrupt this feedback loop to effectively reverse AURKA levels, thereby providing a promising avenue for developing safer AURKA-targeted therapeutics. Additionally, exploring the synergistic effects of AURKA inhibition with its other oncogenic and/or tumor-suppressor targets could provide further opportunities for developing effective combination therapies against AURKA-driven cancers, thereby maximizing its potential as a critical drug target.

NSD family proteins: Rising stars as therapeutic targets

Epigenetic modifications, including DNA methylation and histone post-translational modifications, intricately regulate gene expression patterns by influencing DNA accessibility and chromatin structure in higher organisms. These modifications are heritable, are independent of primary DNA sequences, undergo dynamic changes during development and differentiation, and are frequently disrupted in human diseases. The reversibility of epigenetic modifications makes them promising targets for therapeutic intervention and drugs targeting epigenetic regulators (e.g., tazemetostat, targeting the H3K27 methyltransferase EZH2) have been applied in clinical therapy for multiple cancers. The NSD family of H3K36 methyltransferase enzymes-including NSD1 (KMT3B), NSD2 (MMSET/WHSC1), and NSD3 (WHSC1L1)-are now receiving drug development attention, with the exciting advent of an NSD2 inhibitor (KTX-1001) advancing to Phase I clinical trials for relapsed or refractory multiple myeloma. NSD proteins recognize and catalyze methylation of histone lysine marks, thereby regulating chromatin integrity and gene expression. Multiple studies have implicated NSD proteins in human disease, noting impacts from translocations, aberrant expression, and various dysfunctional somatic mutations. Here, we review the biological functions of NSD proteins, epigenetic cooperation related to NSD proteins, and the accumulating evidence linking these proteins to developmental disorders and tumorigenesis, while additionally considering prospects for the development of innovative epigenetic therapies.

Epigenetic Alterations as Vital Aspects of Bortezomib Molecular Action

Bortezomib (BTZ) is widely implemented in the treatment of multiple myeloma (MM). Its main mechanism of action is very well established. BTZ selectively and reversibly inhibits the 26S proteasome. More precisely, it interacts with the chymotryptic site of the 20S proteasome and therefore inhibits the degradation of proteins. This results in the intracellular accumulation of misfolded or otherwise defective proteins leading to growth inhibition and apoptosis. As well as interfering with the ubiquitin-proteasome complex, BTZ elicits various epigenetic alterations which contribute to its cytotoxic effects as well as to the development of BTZ resistance. In this review, we summarized the epigenetic alterations elicited by BTZ. We focused on modifications contributing to the mechanism of action, those mediating drug-resistance development, and epigenetic changes promoting the occurrence of peripheral neuropathy. In addition, there are therapeutic strategies which are specifically designed to target epigenetic changes. Herein, we also reviewed epigenetic agents which might enhance BTZ-related cytotoxicity or restore the sensitivity to BTZ of resistant clones. Finally, we highlighted putative future perspectives regarding the role of targeting epigenetic changes in patients exposed to BTZ.

A novel glycolysis-related gene signature for predicting the prognosis of multiple myeloma

Background: Metabolic reprogramming is an important hallmark of cancer. Glycolysis provides the conditions on which multiple myeloma (MM) thrives. Due to MM's great heterogeneity and incurability, risk assessment and treatment choices are still difficult. Method: We constructed a glycolysis-related prognostic model by Least absolute shrinkage and selection operator (LASSO) Cox regression analysis. It was validated in two independent external cohorts, cell lines, and our clinical specimens. The model was also explored for its biological properties, immune microenvironment, and therapeutic response including immunotherapy. Finally, multiple metrics were combined to construct a nomogram to assist in personalized prediction of survival outcomes. Results: A wide range of variants and heterogeneous expression profiles of glycolysis-related genes were observed in MM. The prognostic model behaved well in differentiating between populations with various prognoses and proved to be an independent prognostic factor. This prognostic signature closely coordinated with multiple malignant features such as high-risk clinical features, immune dysfunction, stem cell-like features, cancer-related pathways, which was associated with the survival outcomes of MM. In terms of treatment, the high-risk group showed resistance to conventional drugs such as bortezomib, doxorubicin and immunotherapy. The joint scores generated by the nomogram showed higher clinical benefit than other clinical indicators. The in vitro experiments with cell lines and clinical subjects further provided convincing evidence for our study. Conclusion: We developed and validated the utility of the MM glycolysis-related prognostic model, which provides a new direction for prognosis assessment, treatment options for MM patients.