Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK.
Department of Oncology and Metabolism, Sheffield Myeloma Research Team, Medical School, University of Sheffield, Sheffield, UK.
Oncogene. 2020 Jul;39(27):5001-5014. doi: 10.1038/s41388-020-1345-x. Epub 2020 Jun 10.
Proteasome inhibitors have provided a significant advance in the treatment of multiple myeloma (MM). Consequently, there is increasing interest in developing strategies to target E3 ligases, de-ubiquitinases, and/or ubiquitin receptors within the ubiquitin proteasome pathway, with an aim to achieve more specificity and reduced side-effects. Previous studies have shown a role for the E3 ligase HUWE1 in modulating c-MYC, an oncogene frequently dysregulated in MM. Here we investigated HUWE1 in MM. We identified elevated expression of HUWE1 in MM compared with normal cells. Small molecule-mediated inhibition of HUWE1 resulted in growth arrest of MM cell lines without significantly effecting the growth of normal bone marrow cells, suggesting a favorable therapeutic index. Studies using a HUWE1 knockdown model showed similar growth inhibition. HUWE1 expression positively correlated with MYC expression in MM bone marrow cells and correspondingly, genetic knockdown and biochemical inhibition of HUWE1 reduced MYC expression in MM cell lines. Proteomic identification of HUWE1 substrates revealed a strong association of HUWE1 with metabolic processes in MM cells. Intracellular glutamine levels are decreased in the absence of HUWE1 and may contribute to MYC degradation. Finally, HUWE1 depletion in combination with lenalidomide resulted in synergistic anti-MM activity in both in vitro and in vivo models. Taken together, our data demonstrate an important role of HUWE1 in MM cell growth and provides preclinical rationale for therapeutic strategies targeting HUWE1 in MM.
蛋白酶体抑制剂在多发性骨髓瘤 (MM) 的治疗中取得了重大进展。因此，人们越来越感兴趣的是开发针对泛素蛋白酶体途径中的 E3 连接酶、去泛素酶和/或泛素受体的策略，旨在实现更高的特异性和降低副作用。先前的研究表明，E3 连接酶 HUWE1 在调节 c-MYC 中发挥作用，c-MYC 是 MM 中经常失调的癌基因。在这里，我们研究了 HUWE1 在 MM 中的作用。我们发现 MM 中 HUWE1 的表达升高，与正常细胞相比。小分子介导的 HUWE1 抑制导致 MM 细胞系生长停滞，而对正常骨髓细胞的生长没有明显影响，表明治疗指数良好。使用 HUWE1 敲低模型的研究表明类似的生长抑制。HUWE1 表达与 MM 骨髓细胞中的 MYC 表达呈正相关，相应地，HUWE1 的遗传敲低和生化抑制降低了 MM 细胞系中的 MYC 表达。HUWE1 底物的蛋白质组学鉴定表明 HUWE1 与 MM 细胞中的代谢过程密切相关。在没有 HUWE1 的情况下，细胞内谷氨酰胺水平降低，可能导致 MYC 降解。最后，HUWE1 耗竭与来那度胺联合使用在体外和体内模型中均产生协同抗 MM 活性。总之，我们的数据表明 HUWE1 在 MM 细胞生长中起着重要作用，并为针对 MM 中 HUWE1 的治疗策略提供了临床前依据。
