Polyphenols, an important class of natural products, are widely distributed in plant-based foods. These compounds are endowed with several biological activities and exert protective effects in various physiopathological contexts, including cancer. We herein investigated novel potential mechanisms of action of polyphenols, focusing on the proteasome, which has emerged as an attractive therapeutic target in cancers such as multiple myeloma. We carried out a structure-based virtual screening study using the DrugBank database as a repository of FDA-approved polyphenolic molecules. Starting from 86 polyphenolic compounds, based on the theoretical binding affinity and the interactions established with key residues of the chymotrypsin binding site, we selected 2 promising candidates, namely Hesperidin and Diosmin. The further assessment of the biologic activity highlighted, for the first time, the capability of these two molecules to inhibit the β5-proteasome activity and to exert anti-tumor activity against proteasome inhibitor-sensitive or resistant multiple myeloma cell lines.

Mitochondria are highly dynamic organelles that integrate metabolic regulation, signal transduction, and programmed cell death with their canonical role in adenosine triphosphate (ATP) production. Their ability to undergo continuous remodeling through the opposing processes of fusion and fission is essential for maintaining cellular homeostasis, preserving organelle quality control, and enabling adaptive responses to metabolic and oxidative stress. Among the core regulators of mitochondrial dynamics, the dynamin-related guanosine triphosphatase (GTPase) OPA1 plays a central role in inner membrane fusion, cristae architecture maintenance, bioenergetic efficiency, and the modulation of redox balance and apoptotic signaling. Accumulating evidence indicates that dysregulation of OPA1 expression or activity contributes to the initiation and progression of multiple malignancies, underscoring its importance in tumor cell survival, proliferation, metabolic adaptation, and resistance to stress. Here, we summarize current knowledge on OPA1 dysregulation in cancer and, based on preliminary, unpublished in silico analyses, we highlight the growing relevance of OPA1 as a therapeutic target, particularly through its GTPase domain and the still understudied Interface 7. Overall, these findings outline how integrated computational approaches could potentially guide the identification of novel OPA1 modulators, offering a conceptual framework that highlights OPA1 as a promising, yet still largely underexplored, target in oncology.

Background: Histone deacetylase 6 (HDAC6) is a unique class IIb HDAC isozyme characterized by two catalytic domains and a zinc finger ubiquitin-binding domain. It plays critical roles in various cellular processes, including protein degradation, autophagy, immune regulation, and cytoskeletal dynamics. Due to its multifunctional nature and overexpression in several cancer types, HDAC6 has emerged as a promising therapeutic target. Methods: In this study, we employed a ligand-based pharmacophore modeling approach using a structurally diverse set of known HDAC6 inhibitors. This was followed by the virtual screening of over 140,000 commercially available compounds from both the MolPort and Asinex databases. The screening workflow incorporated pharmacophore filtering, molecular docking, and molecular dynamic (MD) simulations. Binding free energies were estimated using Molecular Mechanics Generalized Born Surface Area (MM-GBSA) analysis to prioritize top candidates. A fluorometric enzymatic assay was used to measure HDAC6 activity, while cell viability assay by Cell Titer Glo was used to assess the anti-tumor activity against drug-sensitive and -resistant multiple myeloma (MM) cells. Western blotting was used to evaluate the acetylation of tubulin or histone H4 after treatment with selected compounds. Results: Three promising compounds were identified based on stable binding conformations and favorable interactions within the HDAC6 catalytic pocket. Among them, Molecular Mechanics Generalized Born Surface Area (MM-GBSA) analysis identified Compound 10 (AKOS030273637) as the top theoretical binder, with a ΔG_bind value of −45.41 kcal/mol. In vitro enzymatic assays confirmed its binding to the HDAC6 catalytic domain and inhibitory activity. Functional studies on MM cell lines, including drug-resistant variants, showed that Compound 10 reduced cell viability. Increased acetylation of α-tubulin, a substrate of HDAC6, likely suggested on-target mechanism of action. Conclusions: Compound 10, featuring a benzyl 4-[4-(hydroxyamino)-4-oxobutylidene] piperidine-1-carboxylate scaffold, demonstrates potential drug-like properties and a predicted bidentate zinc ion coordination, supporting its potential as an HDAC6 inhibitor for further development in hematologic malignancies.