Latour Simon, Zanese Marion, Le Morvan Valérie, Vacher Anne-Marie, Menard Nelly, Bijou Fontanet, Durrieu Francoise, Soubeyran Pierre, Savina Ariel, Vacher Pierre, Bresson-Bepoldin Laurence
Institut Bergonié, Comprehensive Cancer Centre, F-33000 Bordeaux, France.
Department of Life and Health Sciences, University of Bordeaux, F-33076 Bordeaux, France.
Cancers (Basel). 2019 Mar 1;11(3):291. doi: 10.3390/cancers11030291.
GA101/obinutuzumab is a novel type II anti-CD20 monoclonal antibody (mAb), which is more effective than rituximab (RTX) in preclinical and clinical studies when used in combination with chemotherapy. Ca signaling was shown to play a role in RTX-induced cell death. This report concerns the effect of GA101 on Ca signaling and its involvement in the direct cell death induced by GA101. We reveal that GA101 triggered an intracellular Ca increase by mobilizing intracellular Ca stores and activating Orai1-dependent Ca influx in non-Hodgkin lymphoma cell lines and primary B-Cell Chronic Lymphocytic Leukemia (B-CLL) cells. According to the cell type, Ca was mobilized from two distinct intracellular compartments. In Raji, BL2, and B-CLL cells, GA101 induced a Ca release from lysosomes, leading to the subsequent lysosomal membrane permeabilization and cell death. Inhibition of this calcium signaling reduced GA101-induced cell death in these cells. In SU-DHL-4 cells, GA101 mobilized Ca from the endoplasmic reticulum (ER). Inhibition of ER replenishment, by blocking Orai1-dependent Ca influx, led to an ER stress and unfolded protein response (UPR) which sensitized these cells to GA101-induced cell death. These results revealed the central role of Ca signaling in GA101's action mechanism, which may contribute to designing new rational drug combinations improving its clinical efficacy.
GA101/奥滨尤妥珠单抗是一种新型的II型抗CD20单克隆抗体（mAb），在临床前和临床研究中，与化疗联合使用时，其疗效优于利妥昔单抗（RTX）。研究表明，Ca信号在RTX诱导的细胞死亡中发挥作用。本报告关注GA101对Ca信号的影响及其在GA101诱导的直接细胞死亡中的作用。我们发现，GA101通过动员细胞内Ca储存并激活非霍奇金淋巴瘤细胞系和原发性B细胞慢性淋巴细胞白血病（B-CLL）细胞中依赖Orai1的Ca内流，触发细胞内Ca增加。根据细胞类型的不同，Ca从两个不同的细胞内区室被动员。在Raji、BL2和B-CLL细胞中，GA101诱导溶酶体释放Ca，导致随后的溶酶体膜通透性增加和细胞死亡。抑制这种钙信号可减少GA101在这些细胞中诱导的细胞死亡。在SU-DHL-4细胞中，GA101从内质网（ER）动员Ca。通过阻断依赖Orai1的Ca内流来抑制ER补充，会导致ER应激和未折叠蛋白反应（UPR），从而使这些细胞对GA101诱导的细胞死亡敏感。这些结果揭示了Ca信号在GA101作用机制中的核心作用，这可能有助于设计新的合理药物组合以提高其临床疗效。
