Department of Hygiene, Kawasaki Medical School, Kurashiki, Japan.
Int J Immunopathol Pharmacol. 2009 Oct-Dec;22(4):879-88. doi: 10.1177/039463200902200403.
YT-CB5, which had been continuously cultured with chrysotile B (CB)asbestos, showed impaired cytotoxicity with decreased expression of NKG2D and 2B4 NK cell-activating receptors. In the present study, the phosphorylation of extracellular signal-regulated kinase (ERK), which is known to induce degranulation downstream of many NK cell-activating receptors, was examined in YT-CB5 by flow cytometry and compared with the control line YT-Org. YT-CB5 exhibited impaired phosphorylation of ERK1/2 induced by the recognition of K562 cells, downstream of a process mediated by Src family kinase and phosphoinositide 3-kinase. YT-CB5 also exhibited impaired phosphorylation of ERK1/2 following incubation with K562 cells in the presence of anti-2B4 antibodies, where co-stimulation by 2B4 augmented the phosphorylation of ERK1/2 in YT-CB5 to a similar degree as in YT-Org. The phosphorylation of ERK1/2 induced by an inhibitor against phosphatase (PP) 1 and PP2A was also lower in YT-CB5 compared with YT-Org. Moreover, bead-bound antibodies to NKG2D, which contribute to cytotoxicity against K562 cells, induced negligible phosphorylation of ERK1/2 in YT-CB5, although antibodies to 2B4 induced a comparatively greater level of phosphorylation. Additionally, peripheral blood (PB-) NK cells with low expression of NKG2D showed lower phosphorylation of ERK1/2 mediated by anti-NKG2D antibodies compared with PB-NK cells with high expression of NKG2D. These results indicate that signal transduction events leading to the phosphorylation of ERK is impaired in YT-CB5 due to decreased expression of NKG2D. Further studies are required to clarify whether this suppressive effect of asbestos exposure on NK cells might promote lung cancer and mesothelioma in people who have inhaled asbestos.
YT-CB5 细胞株在含有温石棉的培养基中连续培养后，其细胞毒性减弱，NKG2D 和 2B4 等 NK 细胞激活受体的表达水平降低。本研究通过流式细胞术检测到 YT-CB5 细胞中已知可诱导多种 NK 细胞激活受体下游脱颗粒的细胞外信号调节激酶（ERK）磷酸化，与对照细胞株 YT-Org 进行比较。YT-CB5 细胞识别 K562 细胞后，ERK1/2 的磷酸化受到抑制，该过程由 Src 家族激酶和磷酸肌醇 3-激酶介导。在用抗 2B4 抗体孵育 K562 细胞时，YT-CB5 细胞中 ERK1/2 的磷酸化也受到抑制，2B4 的共刺激作用可使 YT-CB5 细胞中 ERK1/2 的磷酸化增强到与 YT-Org 相似的程度。与 YT-Org 相比，YT-CB5 细胞中 PP1 和 PP2A 抑制剂诱导的 ERK1/2 磷酸化水平也较低。此外，与 2B4 抗体相比，针对 NKG2D 的结合珠抗体诱导的对 K562 细胞的细胞毒性所导致的 ERK1/2 磷酸化程度可忽略不计，尽管 2B4 抗体诱导了相对更高水平的磷酸化。此外，与高表达 NKG2D 的 PB-NK 细胞相比，低表达 NKG2D 的 PB-NK 细胞通过抗 NKG2D 抗体介导的 ERK1/2 磷酸化水平较低。这些结果表明，由于 NKG2D 表达降低，导致 YT-CB5 细胞中 ERK 磷酸化的信号转导事件受损。需要进一步研究来阐明暴露于石棉对 NK 细胞的这种抑制作用是否会促进吸入石棉的人群患肺癌和间皮瘤。
