5-氨基乙酰丙酸介导的光动力学对裸鼠人胃癌移植瘤的治疗作用

目的观察5-氨基乙酰丙酸（5-ALA）介导的光动力学治疗对裸鼠人胃癌移植瘤的治疗作用。探索5-ALA介导的光动力学（PDT）治疗胃癌的可能机制。方法以MGC-803人胃癌细胞制备裸鼠人胃癌移植瘤模型：整体荧光成像系统下观察动物瘤体发出的荧光信号：测量荷瘤对照组、单纯激光组、单纯5-ALA组和5-ALA介导的PDT治疗组治疗后第1、3、7、14、21天的裸鼠肿瘤大小并计算肿瘤体积：末次测量后切除肿瘤行病理检查和透射电镜观察，TUNEL法检测组织细胞凋亡。结果常规方法培养MGC一803人胃癌细胞并接种裸鼠．可以成功制备出裸鼠人胃癌移植瘤的模型：荷瘤裸鼠肿瘤组织在特定波长的荧光激发下可发出特有的红色荧光。荷瘤对照组、单纯激光组、单纯5-ALA组和5-ALA介导的PDT治疗组治疗后第1、3、7、14、21天4组间的肿瘤体积差异有统计学意义（肚1003．086，P=0．000），PDT治疗组明显小于其他3组；病理检查提示．PDT治疗后肿瘤细胞大片凝固性坏死；透射电镜观察提示，PDT治疗组肿瘤组织存在大量死亡细胞及部分凋亡细胞：TUNEL法检测发现，PDT治疗组的肿瘤组织凋亡指数显著高于其他3组（χ^2=18．237．P=0．000）。结论5-ALA介导的PDT对于裸鼠人胃癌移植瘤具有明显的治疗效果．而单纯给予5-ALA或激光辐射对肿瘤无明显抑制作用；肿瘤细胞的坏死及凋亡是5-ALA介导的PDT产生细胞毒作用的重要机制。

Effect of 5-aminolevulinic acid-mediated photodynamic therapy on human gastric cancer xenografts in nude mice in vivo

Objective To investigate the effect of 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) on human gastric cancer xenografts in vivo and to explore its potential tumoreidal mechanism. Methods Cultured MGC-803 human gastric cancer cells were injected below the skins of the nude mice to develop the tumor model. The tumor-bearing nude mice were examined under the Leica LT-9MACIMSYSPULS to detect the fluorescence. The tumor volume of day 1, 3, 7, 14, 21 after treatment were measured, and its histological changes were also studied. The tissues of the tumors in nude mice of the control group, light group, 5-ALA group and PDT group were examined with the electron microscope and apoptosis was detected by TUNEL assay. Results The tumor model was successfully developed. The tumor in the nude mice emited the red fluorescence under the Leica LT-9MACIMSYSPULS. The tumor volumes were (0.189±0.010)cm3, (0.183±0.011)cm3, (0.185±0.019) cm3, (0.182±0.015)cm3 for the control group, light group, 5-ALA group, PDT group, respectively at day 1 after treatment, while at day 3, (0.294±0.010)cm3, (0.280±0.013)cm3, (0.278±0.016)cm3, (0.183±0.014)cm3;at day 7, (0.409±0.016)cm3, (0.411±0.009)cm3, (0.407±0.015)cm3, (0.221±0.008)cm3;at day 14, (0.970±0.055)cm3 (0.976±0.054)cm3, (0.981±0.032)cm3, (0.318±0.005)cm3;at day 21, (1.495±0.059)cm3, (1.513±0.057)cm3, ( 1.524±0.063)cm3, (0.446±0.042)cm3(F=1003.086, P=0.000). The histology demonstrated that most tumor blood vessels were congested and necrosis developed after PDT while not in the control group, light group and 5-ALA group. Necrosis and apoptosis were observed in the cells of the tumors of the PDT group examined by TUNEL and electron microscope while not in the cells of the tumors of the other groups. Conclusions 5-aminolevulinic acid-mediated photodynamic therapy (PDT) can induce injury to human gastric cancer xenografts and inhibit the tumor growth while light only and 5-ALA only can not. 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) appears to be a promising therapy for human gastric cancer, whose mechanism involves in the destruction of the tumors partly by apoptosis other than necrosis.