Chen Yirong, Tao Yuchen, Hu Kexin, Lu Jiahui
Department of Hematology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200071, China.
Heliyon. 2023 Sep 2;9(9):e19806. doi: 10.1016/j.heliyon.2023.e19806. eCollection 2023 Sep.
Bortezomib (BTZ), a selective proteasome inhibitor, exhibits a significant efficacy in the therapy of multiple myeloma (MM) partly through triggering endoplasmic reticulum (ER) stress-dependent apoptosis. However, sensitivity to BTZ varies greatly among patients. ER stress functions as a double-edged sword in regulating cell survival depending on cell context and ER stress extent. The major aim of this study was to investigate whether GRP78 inhibitor, HA15, increased the therapeutic effect of BTZ on MM to through further increasing ER stress and shifting the balance towards cell apoptosis. The biological role of BTZ and HA15 was assessed using Cell counting kit- (CCK-) 8, colony formation, and Terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labelling (TUNEL) assay. We found that BTZ combined with HA15 remarkably decreased MM cell viability more effective than BTZ monotherapy, though low dose of HA15 did not exhibit a significant cytotoxicity to MM cells. BTZ combined with HA15 also repressed colony formation ability of MM cell and accelerated MM cell apoptosis compared with BTZ monotherapy. Mechanistically, HA15 synergized with BTZ to trigger ER stress, as evidence by significantly increased expression of ER stress markers (GRP78, ATF4, CHOP, and XBP1). Importantly, unfolded protein response (UPR) inhibitor significantly damaged the effect of BTZ combined with HA15 on accelerating MM cell death. , combination treatment with BTZ and HA15 inhibited tumor growth more effective than BTZ alone, whereas these effects were blocked by UPR inhibitor. Taken together, these results demonstrate that ER stress is a critical pathway in regulating MM cell survival, and that combination treatment with BTZ and HA15 may be an effective strategy to treat MM patients that fail to respond to BTZ monotherapy.
硼替佐米（BTZ）是一种选择性蛋白酶体抑制剂，在多发性骨髓瘤（MM）治疗中显示出显著疗效，部分原因是通过触发内质网（ER）应激依赖性凋亡。然而，患者对BTZ的敏感性差异很大。内质网应激在调节细胞存活中起着双刃剑的作用，这取决于细胞环境和内质网应激程度。本研究的主要目的是探讨GRP78抑制剂HA15是否通过进一步增加内质网应激并使平衡向细胞凋亡倾斜来增强BTZ对MM的治疗效果。使用细胞计数试剂盒（CCK）-8、集落形成和末端脱氧核苷酸转移酶（TdT）dUTP缺口末端标记（TUNEL）试验评估了BTZ和HA15的生物学作用。我们发现，BTZ与HA15联合使用比BTZ单药治疗更显著地降低MM细胞活力，尽管低剂量的HA15对MM细胞没有显著的细胞毒性。与BTZ单药治疗相比，BTZ与HA15联合使用还抑制了MM细胞的集落形成能力并加速了MM细胞凋亡。机制上，HA15与BTZ协同触发内质网应激，内质网应激标志物（GRP78、ATF4、CHOP和XBP1）的表达显著增加证明了这一点。重要的是，未折叠蛋白反应（UPR）抑制剂显著破坏了BTZ与HA15联合使用对加速MM细胞死亡的作用。此外，BTZ与HA15联合治疗比单独使用BTZ更有效地抑制肿瘤生长，而这些作用被UPR抑制剂阻断。综上所述，这些结果表明内质网应激是调节MM细胞存活的关键途径，并且BTZ与HA15联合治疗可能是治疗对BTZ单药治疗无反应的MM患者的有效策略。
