新型光敏药物对胃癌MGC803细胞的光动力学治疗研究

A new photodynamic therapy drug toward gastric cancer MGC803 cell

目的探讨一种新型光敏药物对人胃癌细胞MGC803的光动力学治疗（PDT）作用及其机制。方法采用bleaching光漂白法评价中国医学科学院生物医学工程研究所纳米与分子设计实验室合成的新型光敏药物（药物A）的光稳定性：MTT法检测药物A对MGC803细胞的杀伤作用；共聚焦激光显微镜（LSCM）观察药物在MGC803细胞内定位情况：Hoechst染色和流式细胞术（Annexin Ⅴ／PI双染）检测PDT后细胞死亡方式。结果光照实验表明，药物A对光比较稳定：MTT结果显示，药物A自身对MGC803细胞无暗毒性作用（P〉0．05），单纯光照本身对细胞生长亦无任何影响（P〉0．05），但光照后药物A对MGC803细胞有强烈杀伤作用（P〈0．05），半数致死剂量LD加值为1．74μmol／L，当药物A浓度为3．12μmol／L时，细胞存活率为（17．3±1．8）％，浓度继续增加药效不再增加：LSCM观察显示，药物定位于MGC803细胞溶酶体内；Hoechst染色和AnnexinⅤ／PI双染表明．细胞死亡方式主要为坏死。结论药物A是一种能够有效杀伤胃癌MGC803细胞的新型光敏药物。

Objective To investigate the treatment efficiency of a new photodynamic therapeutic （PDT） drug synthesized by our laboratory toward MGC803 cells and related mechanisms. Methods Bleaching method was used to evaluate the photostability of drug upon repetitive illumination. MTT assay was used to determine the ability of new drug killing MGC803 cells after PDT. Laser scanning confocal microscopy （LSCM） was applied to investigate the subcellular localization of drug in MGCS03 cells （mitochondria and/or lysosomes）. Hoechst staining and flow cytometry （Annexin V/PI double-staining） were performed to detect the death mode of MGC803 cells after PDT. Results This new PDT drug had good stability to light irradiation after repetitive illumination. MTr assay showed no cytotoxicity towards MGC803 cells only by drug or only by irradiation（P〉0.05）, but intense lethal effect was observed with drug and light combination （P〈0.05）. The phototoxicity of medicine increased with the elevation of concentration, the LD50 was 1.74 μmol/L, and reaching plateau at the concentration of 3.12 μmol/L, even increasing the concentration. LSCM found that drug localized in lysosomes of MGC803 cells. Hoechst staining showed that the death mode of cells was mainly necrosis and Annexin V/PI double- staining proved this result further. Conclusion This new PDT drug is an effective PDT sensitizer for MGC803 cells and the death mode of cells is mainly necrosis.