Department of Otorhinolaryngology, University Medical Center Regensburg, Franz-Josef-Strauß-Allee 11, 93053, Regensburg, Germany.
Department of Orthopedic Surgery, Division of Experimental Orthopedics, University Medical Center Regensburg, Biopark I / ZMB, Am Biopark 9, 93053, Regensburg, Germany.
Clin Oral Investig. 2018 Jul;22(6):2251-2262. doi: 10.1007/s00784-017-2323-8. Epub 2018 Jan 6.
Head and neck squamous cell carcinoma (HNSCC) shows increased radioresistance due to the manipulation of homeostatic mechanisms like the heat shock response. This study intended to comparatively analyze effects of ionizing radiation on different HNSCC cell lines (PCI) and normal human dermal fibroblasts (NHFs) and human dermal microvascular endothelial cells (HDMECs) to uncover differences in radiation coping strategies.
Proliferation (BrdU assay), apoptosis (caspase 3/7) and intracellular protein expression of heat shock protein (HSP)-70, and phosphorylated and total HSP27, determined by enzyme-linked immunosorbent assay (ELISA), were analyzed after exposure to increasing doses of ionizing radiation (2, 6, and 12 Gray, Gy).
Cell count decreased dose-dependently, but PCI cell lines consistently showed higher numbers compared to NHF and HDMEC. Likewise, high doses reduced cell proliferation, but low-dose radiation (2 Gy) instead increased proliferation in PCI 9 and 52. Apoptosis was not detectable in PCI cell lines. Basic HSP70 expression was high in PCI cells with little additional increase by irradiation. PCI cells yielded high basic total HSP27 concentrations but irradiation dose-dependently increased HSP27 in HDMEC, NHF, and PCI cells. Phosphorylated HSP27 concentrations were highest in NHF.
PCI cell lines showed higher resistance to dose-dependent reduction in cell number, proliferation, and protection from apoptosis compared to NHF and HDMEC. In parallel, we observed a high basic and radiation-induced expression of intracellular HSP70 leading to the assumption that the radioresistance of PCI cells is conferred by HSP70.
HNSCC use HSP to escape radiation-induced apoptosis and certain subtypes might increase proliferation after low-dose irradiation.
头颈部鳞状细胞癌（HNSCC）由于热休克反应等稳态机制的调控，表现出增强的放射抗性。本研究旨在比较分析电离辐射对不同 HNSCC 细胞系（PCI）和正常人类皮肤成纤维细胞（NHF）和人真皮微血管内皮细胞（HDMEC）的影响，以揭示辐射应对策略的差异。
通过酶联免疫吸附试验（ELISA）测定细胞增殖（BrdU 测定）、细胞凋亡（caspase 3/7）和热休克蛋白（HSP）-70、磷酸化和总 HSP27 的细胞内蛋白表达，在暴露于不同剂量的电离辐射（2、6 和 12 Gy）后进行分析。
细胞计数呈剂量依赖性下降，但 PCI 细胞系的细胞数始终高于 NHF 和 HDMEC。同样，高剂量降低细胞增殖，但低剂量辐射（2 Gy）反而增加了 PCI 9 和 52 的增殖。在 PCI 细胞系中未检测到细胞凋亡。基础 HSP70 表达在 PCI 细胞中较高，照射后略有增加。PCI 细胞产生高基础总 HSP27 浓度，但 HSP27 随辐射剂量增加在 HDMEC、NHF 和 PCI 细胞中增加。磷酸化 HSP27 浓度在 NHF 中最高。
与 NHF 和 HDMEC 相比，PCI 细胞系表现出更高的抵抗剂量依赖性细胞数量减少、增殖和抗凋亡的能力。平行地，我们观察到细胞内 HSP70 的基础表达和辐射诱导表达均较高，这导致我们假设 PCI 细胞的放射抗性是由 HSP70 赋予的。
HNSCC 利用 HSP 逃避辐射诱导的细胞凋亡，某些亚型在低剂量照射后可能会增加增殖。
