PDF(Pubmed)
Abstract：
Venetoclax and obinutuzumab are becoming frontline therapies for chronic lymphocytic leukemia (CLL) patients. Unfortunately, drug resistance still occurs, and the combination could be immunosuppressive. Lysosomes have previously been identified as a target for obinutuzumab cytotoxicity in CLL cells, but the mechanism remains unclear. In addition, studies have shown that lysosomotropic agents can cause synergistic cell death in vitro when combined with the BTK inhibitor, ibrutinib, in primary CLL cells. This indicates that targeting lysosomes could be a treatment strategy for CLL. In this study, we have shown that obinutuzumab induces lysosome membrane permeabilization (LMP) and cathepsin D release in CLL cells. Inhibition of cathepsins reduced obinutuzumab-induced cell death in CLL cells. We further determined that the lysosomotropic agent siramesine in combination with venetoclax increased cell death in primary CLL cells through an increase in reactive oxygen species (ROS) and cathepsin release. Siramesine treatment also induced synergistic cytotoxicity when combined with venetoclax. Microenvironmental factors IL4 and CD40L or incubation with HS-5 stromal cells failed to significantly protect CLL cells from siramesine- and venetoclax-induced apoptosis. We also found that siramesine treatment inhibited autophagy through reduced autolysosomes. Finally, the autophagy inhibitor chloroquine failed to further increase siramesine-induced cell death. Taken together, lysosome-targeting drugs could be an effective strategy in combination with venetoclax to overcome drug resistance in CLL.
摘要：
Venetoclax和obinutuzumab正在成为慢性淋巴细胞白血病（CLL）患者的一线治疗方法。不幸的是,耐药性仍然存在，这种组合可能具有免疫抑制作用。溶酶体先前已被确定为CLL细胞中obinutuzumab细胞毒性的靶标，但机制尚不清楚。此外,研究表明，当与BTK抑制剂联合使用时，溶酶体激动剂可以在体外引起协同细胞死亡，伊布替尼,在原代CLL细胞中。这表明靶向溶酶体可能是CLL的治疗策略。在这项研究中,我们已经证明奥比妥珠单抗诱导CLL细胞中溶酶体膜透化(LMP)和组织蛋白酶D释放.组织蛋白酶的抑制减少了CLL细胞中奥比妥珠单抗诱导的细胞死亡。我们进一步确定，与维奈托克联合使用的溶菌药西拉米西汀通过增加活性氧（ROS）和组织蛋白酶的释放来增加原代CLL细胞的细胞死亡。当与维奈托克联用时,西拉美辛治疗也诱导协同细胞毒性。微环境因素IL4和CD40L或与HS-5基质细胞孵育未能显着保护CLL细胞免受西拉西汀和维奈托克诱导的凋亡。我们还发现西拉美辛治疗通过减少自体溶酶体抑制自噬。最后,自噬抑制剂氯喹未能进一步增加西拉美辛诱导的细胞死亡.一起来看,溶酶体靶向药物与维奈托克联合使用可能是克服CLL耐药性的有效策略。
