Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, and Clinical Cooperation Group (CCG) "Innate Immunity in Tumor Biology", Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Munich, Germany.
PLoS One. 2012;7(7):e41341. doi: 10.1371/journal.pone.0041341. Epub 2012 Jul 19.
We have previously reported that human recombinant granzyme B (grB) mediates apoptosis in membrane heat shock protein 70 (Hsp70)-positive tumor cells in a perforin-independent manner.
METHODOLOGY/PRINCIPAL FINDINGS: Optical imaging of uptake kinetics revealed co-localization of grB with recycling endosomes (Rab9/11) as early as 5 min after internalization, with late endosomes (Rab7) after 30 min, and the lysosomal compartment (LAMP1/2) after 60 to 120 min. Active caspase-3-mediated apoptosis was induced in mouse CT26 monolayer cells and 3D tumor spheroids, but not in normal mouse endothelial cells. Granzyme B selectively reduced the proportion of membrane Hsp70-positive cells in CT26 tumor spheroids. Consecutive i.v. injections of recombinant human grB into mice bearing membrane Hsp70-positive CT26 tumors resulted in significant tumor suppression, and a detailed inspection of normal mouse organs revealed that the administration of anti-tumoral concentrations of grB elicited no clinicopathological changes.
CONCLUSIONS/SIGNIFICANCE: These findings support the future clinical evaluation of human grB as a potential adjuvant therapeutic agent, especially for treating immunosuppressed patients that bear membrane Hsp70-positive tumors.
我们之前曾报道过，人重组颗粒酶 B（grB）以穿孔素非依赖性方式介导膜热休克蛋白 70（Hsp70）阳性肿瘤细胞的凋亡。
方法/主要发现：摄取动力学的光学成像显示，grB 早在内化后 5 分钟就与再循环内体（Rab9/11）共定位，30 分钟后与晚期内体（Rab7）共定位，60 至 120 分钟后与溶酶体区室（LAMP1/2）共定位。在小鼠 CT26 单层细胞和 3D 肿瘤球体中诱导了活性 caspase-3 介导的凋亡，但在正常小鼠内皮细胞中没有诱导。颗粒酶 B 选择性降低 CT26 肿瘤球体中膜 Hsp70 阳性细胞的比例。连续静脉注射重组人 grB 到携带膜 Hsp70 阳性 CT26 肿瘤的小鼠中，导致显著的肿瘤抑制，对正常小鼠器官的详细检查表明，给予抗肿瘤浓度的 grB 不会引起临床病理变化。
结论/意义：这些发现支持将来将人 grB 作为潜在的辅助治疗剂进行临床评估，特别是用于治疗携带膜 Hsp70 阳性肿瘤的免疫抑制患者。
