Akhlynina T V, Rosenkranz A A, Jans D A, Sobolev A S
Department of Biomembranes, Research Center of Molecular Diagnostics and Therapy, Moscow, Russia.
Cancer Res. 1995 Mar 1;55(5):1014-9.
Photodynamic therapy has been applied quite extensively over the last few years, whereby the activation of photosensitizers by light causes the production of reactive oxygen species such as singlet oxygen, which is cytotoxic. The goal of this study was the enhancement of the photodynamic activity of photosensitizers through their delivery to specific, sensitive intracellular compartments of target cells. We synthesized a BSA-insulin-chlorin e6 conjugate that bound specifically to the insulin receptors (EC50, 1 nM) of the human hepatoma cell line PLC/PRF/5 and could be internalized by receptor-mediated endocytosis. Photodynamic activity, as assessed by various tests, indicated EC50s at about 100 times lower concentrations of conjugate compared to free chlorin e6 itself; and lower doses of irradiation were necessary to activate the conjugate compared to free chlorin e6. Inhibition of endocytosis of the conjugate abrogated the enhanced photodynamic activity of the conjugate above that of free chlorin e6. Endocytosis and subsequent localization around and in the cell nucleus of the BSA-insulin-chlorin e6 conjugate could be visualized using both FITC-labeled conjugate and 2',7'-dichlorofluorescin diacetate, a fluorescent indicator of the production of active oxygen species due to chlorin e6 activation. It was concluded that photodynamic activity of the conjugate is higher than that of free chlorin e6 through its receptor-mediated delivery into sensitive intracellular compartments.
在过去几年中，光动力疗法已得到广泛应用，即通过光激活光敏剂会产生如单线态氧等活性氧物质，这些物质具有细胞毒性。本研究的目标是通过将光敏剂递送至靶细胞特定的、敏感的细胞内区室来增强其光动力活性。我们合成了一种牛血清白蛋白 - 胰岛素 - 二氢卟吩e6共轭物，它能特异性结合人肝癌细胞系PLC/PRF/5的胰岛素受体（半数有效浓度为1 nM），并可通过受体介导的内吞作用进入细胞。通过各种测试评估光动力活性，结果表明与游离二氢卟吩e6相比，共轭物在约低100倍的浓度下就达到半数有效浓度；与游离二氢卟吩e6相比，激活共轭物所需的照射剂量更低。抑制共轭物的内吞作用会消除共轭物高于游离二氢卟吩e6的增强光动力活性。使用异硫氰酸荧光素标记的共轭物和二氯荧光素二乙酸酯（一种由于二氢卟吩e6激活而产生活性氧物质的荧光指示剂），可以观察到牛血清白蛋白 - 胰岛素 - 二氢卟吩e6共轭物的内吞作用及其在细胞核周围和细胞核内的后续定位。得出的结论是，共轭物通过受体介导的方式递送至敏感的细胞内区室，其光动力活性高于游离二氢卟吩e6。
