Rincón Rafael, F Coira Isabel, Richieu Antoine, Attana Fedaa, Urwyler Muriel, Haider Shozeb, Bourquin Carole, Bertrand Philippe, Cuendet Muriel
School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, Geneva, Switzerland.
Cell Death Discov. 2025 Apr 15;11(1):176. doi: 10.1038/s41420-025-02465-1.
Multiple myeloma is a plasma cell malignancy with a poor prognosis despite the recent development of new therapeutic options. Histone deacetylase 6 (HDAC6) is overexpressed in multiple myeloma cells and may be involved in the acquisition of resistance to conventional anti-proteasome treatments. In addition to displaying a deacetylase catalytic activity, HDAC6 plays an essential role in the regulation of autophagy and cell death by recognizing ubiquitinated motifs from misfolded proteins through its C-terminal ZnF-UBP binding domain. These defective proteins are sent to the aggresome to facilitate their degradation by autophagy. Here, we explore the role of the ZnF-UBP binding domain of HDAC6 in the function of multiple myeloma cells. A non-functional ZnF-UBP domain containing a 2-residue mutation in the binding site was designed, and the absence of ubiquitin binding was confirmed in a cell-free assay. Molecular docking simulations and electrostatic calculations revealed a significant decrease in the electrostatic potential of the mutated peptide, which is crucial for the stability of the complex with ubiquitin. A multiple myeloma cell line containing the non-functional ZnF-UBP domain was then engineered. Although the deacetylase activity of HDAC6 was maintained in these cells, they showed reduced cell growth, impaired aggresome formation, and a dysregulated gene expression profile that was more pronounced than cells entirely deficient in HDAC6. These results indicate that a non-functional ZnF-UBP binding domain impacts the function of multiple myeloma cells. Based on these findings, a series of quinazolinylpropanoic acid derivatives was synthesized to explore the inhibitory activity of small molecules to this domain. We propose that ZnF-UBP binding domain inhibitors should be further evaluated as potential therapeutic agents in multiple myeloma.
多发性骨髓瘤是一种浆细胞恶性肿瘤，尽管最近有新的治疗方案出现，但其预后仍然很差。组蛋白去乙酰化酶6（HDAC6）在多发性骨髓瘤细胞中过度表达，可能参与了对传统抗蛋白酶体治疗产生耐药性的过程。除了具有去乙酰化酶催化活性外，HDAC6还通过其C末端的ZnF-UBP结合结构域识别错误折叠蛋白的泛素化基序，在自噬和细胞死亡的调节中发挥重要作用。这些有缺陷的蛋白质被送到聚集体中，以便通过自噬促进其降解。在这里，我们探讨了HDAC6的ZnF-UBP结合结构域在多发性骨髓瘤细胞功能中的作用。设计了一个在结合位点含有两个残基突变的无功能ZnF-UBP结构域，并在无细胞试验中证实了其缺乏泛素结合能力。分子对接模拟和静电计算表明，突变肽的静电势显著降低，这对与泛素形成复合物的稳定性至关重要。然后构建了一个含有无功能ZnF-UBP结构域的多发性骨髓瘤细胞系。尽管这些细胞中HDAC6的去乙酰化酶活性得以维持，但它们的细胞生长减缓，聚集体形成受损，基因表达谱失调，且这种失调比完全缺乏HDAC6的细胞更为明显。这些结果表明，无功能的ZnF-UBP结合结构域会影响多发性骨髓瘤细胞的功能。基于这些发现，合成了一系列喹唑啉基丙酸衍生物，以探索小分子对该结构域的抑制活性。我们建议，ZnF-UBP结合结构域抑制剂应作为多发性骨髓瘤的潜在治疗药物进行进一步评估。
