p5091 and Multiple-Myeloma

Multiple myeloma is currently incurable, and the incidence rate is increasing year by year worldwide. Although in recent years the combined treatment plan based on proteasome inhibitors and immunomodulatory drugs has greatly improved the treatment effect of multiple myeloma, most patients still relapse and become resistant to current treatments. To solve this problem, scientists are committed to developing drugs with higher specificity, such as iberdomide, which is highly specific to ikaros and aiolos. This review aims to focus on the small molecular agents that are being researched/clinically used for the treatment of multiple myeloma, including the target mechanism, structure-activity relationship and application prospects of small molecular agents.

Topics: Animals; Antineoplastic Agents; Biomarkers, Tumor; Combined Modality Therapy; Deubiquitinating Enzymes; Drug Development; Drug Resistance; Histone Deacetylases; Humans; Ikaros Transcription Factor; Immunomodulating Agents; Models, Molecular; Morpholines; Multiple Myeloma; Phthalimides; Piperidones; Proteasome Inhibitors; Treatment Outcome; Ubiquitin-Protein Ligases

The Maf proteins, including c-Maf, MafA, and MafB, are critical transcription factors in myelomagenesis. Previous studies demonstrated that Maf proteins are processed by the ubiquitin-proteasome pathway, but the mechanisms remain elusive. This study applied MS to identify MafB ubiquitination-associated proteins and found that the ubiquitin-specific protease USP7 was present in the MafB interactome. Moreover, USP7 also interacted with c-Maf and MafA and blocked their polyubiquitination and degradation. Consistently, knockdown of USP7 resulted in Maf protein degradation along with increased polyubiquitination levels. The action of USP7 thus promoted Maf transcriptional activity as evidenced by luciferase assays and by the up-regulation of the expression of Maf-modulated genes. Furthermore, USP7 was up-regulated in myeloma cells, and it was negatively associated with the survival of myeloma patients. USP7 promoted myeloma cell survival, and when it was inhibited by its specific inhibitor P5091, myeloma cell lines underwent apoptosis. These results therefore demonstrated that USP7 is a deubiquitinase of Maf proteins and promotes MM cell survival in association with Maf stability. Given the significance of USP7 and Maf proteins in myeloma genesis, targeting the USP7/Maf axle is a potential strategy to the precision therapy of MM.

Topics: Apoptosis; Carcinogenesis; Cell Proliferation; Cell Survival; Female; Gene Expression Regulation, Neoplastic; HEK293 Cells; Humans; Maf Transcription Factors, Large; MafB Transcription Factor; Male; Multiple Myeloma; Polyubiquitin; Progression-Free Survival; Proteolysis; Proto-Oncogene Proteins c-maf; Thiophenes; Ubiquitin-Specific Peptidase 7; Ubiquitination

Bortezomib therapy has proven successful for the treatment of relapsed/refractory, relapsed, and newly diagnosed multiple myeloma (MM); however, dose-limiting toxicities and the development of resistance limit its long-term utility. Here, we show that P5091 is an inhibitor of deubiquitylating enzyme USP7, which induces apoptosis in MM cells resistant to conventional and bortezomib therapies. Biochemical and genetic studies show that blockade of HDM2 and p21 abrogates P5091-induced cytotoxicity. In animal tumor model studies, P5091 is well tolerated, inhibits tumor growth, and prolongs survival. Combining P5091 with lenalidomide, HDAC inhibitor SAHA, or dexamethasone triggers synergistic anti-MM activity. Our preclinical study therefore supports clinical evaluation of USP7 inhibitor, alone or in combination, as a potential MM therapy.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Boronic Acids; Bortezomib; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Dexamethasone; Drug Resistance, Neoplasm; Drug Therapy, Combination; Humans; Lenalidomide; Mice; Mice, SCID; Molecular Sequence Data; Multiple Myeloma; Neovascularization, Pathologic; Protease Inhibitors; Proto-Oncogene Proteins c-mdm2; Pyrazines; Random Allocation; Thalidomide; Thiophenes; Ubiquitin Thiolesterase; Ubiquitin-Specific Peptidase 7; Xenograft Model Antitumor Assays