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背景与目的:三磷酸腺苷结合转运蛋白G超家族成员2(adenosine triphosphate-binding cassette superfamily G member 2,ABCG2)在多种肿瘤细胞中表达,能通过外排抗癌药物参与肿瘤耐药。本研究的目的旨在探讨人胶质瘤细胞对焦脱镁叶绿酸甲酯(pyropheophorbide-a methyl ester,MPPa)介导的光动力疗法(photodynamic therapy,PDT)杀伤效应的敏感性及其与ABCG2的关系。方法:选取处于对数生长期的胶质瘤细胞株U87、A172,分别经MPPa-PDT或MPPa-PDT+烟曲霉毒素C(fumitremorgin C,FTC)处理后,采用CCK-8法检测细胞活性;采用蛋白[质]印迹法(Western blot)检测细胞内ABCG2的表达;流式细胞技术法检测未光照前各组细胞内MPPa的含量;AnnexinⅤ-FITC/PI双染流式细胞术检测细胞凋亡率;DCFH-DA染色观察细胞内活性氧(reactive oxygen species,ROS)的产生。结果:MPPa-PDT能抑制A172、U87细胞的活性,且呈一定的光能量依赖性,A172达到半数致死量所需光能量密度为U87的8倍;A172较U87细胞对MPPa-PDT不敏感;A172细胞内高表达的ABCG2影响MPPa在细胞内的聚集;抑制ABCG2后,不仅可以增强MPPa-PDT对A172细胞的杀伤作用,同时可增加MPPa-PDT触发产生的ROS的量及细胞对MPPa的摄取。结论:人胶质瘤细胞株A172对MPPa-PDT相对不敏感,并且产生这种现象的机制可能是ABCG2外排MPPa,减少MPPa的细胞内聚集,进而减弱光敏剂活化后对肿瘤细胞的杀伤作用。
BACKGROUND & OBJECTIVE: Adenosine triphosphate-binding cassette superfamily G member 2 (ABCG2) is expressed in various tumor cells and can be involved in tumor drug resistance through efflux of anticancer drugs. The aim of this study was to investigate the sensitivity of human glioma cells to the photodynamic therapy (PDT) -mediated killing effect of pyropheophorbide-a methyl ester (MPPa) and their association with ABCG2 Relationship. Methods: Glioma cell lines U87 and A172 at logarithmic growth phase were selected and treated with MPPa-PDT or MPPa-PDT + fumitremorgin C (FTC) respectively. Cell viability was determined by CCK-8 assay. Western blot was used to detect the expression of ABCG2 in cells. Flow cytometry was used to detect the MPPa content in cells before irradiation. AnnexinⅤ-FITC / PI double staining was used to detect the apoptosis rate DCFH-DA staining was used to observe the production of intracellular reactive oxygen species (ROS). MPPa-PDT could inhibit the activity of A172 and U87 cells, and showed a certain optical energy dependence. The light energy density needed to reach the median lethal dose of A172 was 8 times that of U87. A172 was less sensitive to MPPa-PDT than U87 cells. ABCG2 overexpression in A172 cells affected MPPa accumulation in the cells. Inhibition of ABCG2 could not only enhance the killing effect of MPPa-PDT on A172 cells, but also increase the amount of ROS induced by MPPa-PDT and the uptake of MPPa by cells . CONCLUSION: The human glioma cell line A172 is relatively insensitive to MPPa-PDT, and the mechanism of this phenomenon may be that the efflux of ABCG2 is MPPa, which decreases the MPPa intracellular accumulation and then attenuates the killing effect of photosensitizer on tumor cells .