Effects of Radiation and High Glucose on Endothelial Dysfunction: an in vitro study

Endothelium is highly radiosensitive, multifunctional, and is the main component of the blood vessel wall. Both radiation and hyperglycaemia could cause endothelial dysfunction, which is the primary injury of radiation-induced and non-radiation-induced carotid atherosclerosis in post-radiotherapy (RT) head and neck carcinoma patients and diabetes patients, respectively. Commonly, some post-RT patients have diabetes simultaneously, leading them to suffer from the accumulative effects of radiation and hyperglycaemia. However, the underlying mechanisms of individual and combined effects of radiation and hyperglycaemia have not been revealed. Human umbilical vein endothelial cells (HUVECs) were used in the study to investigate the individual and combined effects of radiation and high glucose level on endothelial dysfunction in vitro, and possible signalling pathways involved. The cell viability, tube formation and protein levels, including nitric oxide synthesis (NOS), angiogenesis-related [focal adhesion kinase (FAK), vascular endothelial growth factors receptor (VEGFR)], and apoptosis (caspase-3)-related proteins at high/low glucose level combined with 0/8 Gy of radiation were being evaluated. Our findings suggested that radiation suppressed endothelial cell viability (p&lt;0.001), and the combined effects of radiation and high glucose-induced higher angiogenesis of endothelial cells. eNOS-mediated and FAK-mediated signalling transductions are the possible signalling pathways involved in radiation- and hyperglycaemia-induced endothelial dysfunction.血管内皮（endothelium）具有高度辐射敏感性与多功能性，是血管壁的主要构成组分。辐射与高血糖均可诱发内皮功能障碍，分别为放疗（radiotherapy, RT）后头颈部癌患者的辐射诱导性颈动脉粥样硬化，以及糖尿病患者非辐射诱导性颈动脉粥样硬化的始发损伤事件。临床中，部分放疗后患者可同时合并糖尿病，进而承受辐射与高血糖的双重累积损伤效应。然而，辐射与高血糖单独及联合作用的潜在分子机制尚未阐明。 本研究采用人脐静脉内皮细胞（Human umbilical vein endothelial cells, HUVECs），体外探究辐射与高糖单独及联合作用对内皮功能障碍的影响，以及潜在的相关信号通路。本研究评估了不同糖浓度（高/低糖）联合0 Gy、8 Gy辐射剂量处理下的细胞活力、管形成能力，以及相关蛋白表达水平，涵盖一氧化氮合酶（nitric oxide synthesis, NOS）、血管生成相关蛋白[黏着斑激酶（focal adhesion kinase, FAK）、血管内皮生长因子受体（vascular endothelial growth factors receptor, VEGFR）]以及半胱天冬酶-3（caspase-3）相关蛋白。 本研究结果显示，辐射可显著抑制内皮细胞活力（p<0.001），而辐射与高糖的联合作用则可增强内皮细胞的血管生成能力。辐射及高血糖诱导的内皮功能障碍，其潜在信号通路可能涉及内皮型一氧化氮合酶（endothelial nitric oxide synthase, eNOS）介导与FAK介导的信号转导过程。