5-氨基乙酰丙酸介导的光动力学治疗胃癌的实验研究

目的探讨5-氨基乙酰丙酸(5-ALA)介导的光动力学对人胃癌细胞MGC-803的治疗作用.方法将不同浓度的5-ALA加入细胞培养基中,随之给予相同剂量的激光辐射;之后用固定浓度的5-ALA处理细胞,并给予不同剂量的激光辐射.MTT法测定细胞生存率.结果在相同的辐射剂量下,经0.25、0.5、1.0、2.0、4.0 mmol/L的5-ALA处理的细胞生存率分别为(70.07±5.37)%、(50.04±4.99)%、(34.53±5.30)%、(26.89±4.44)%和23.90%±2.80%,除2.0和4.0 mmol/L5-ALA两组间外,其余各组间具有显著性差异(F=266.39,P＜0.001).在相同的5-ALA的浓度下,辐射剂量为6.25、12.5、25.0、50.0、100 J/cm2的细胞生存率分别为(83.50±10.43)%、(67.96±9.23)%、(33.80±8.26)%、(23.31±5.98)%和(14.96±3.50)%,各组之间有显著性差异(F=226.31,P＜0.0001).而单用5-ALA处理细胞,对应于其浓度为0.25、0.5、1.0、2.0,和4.0 mmol/L时的细胞生存率分别为(96.46±6.72)%、(97.48±5.27)%、(98.33±6.67)%、(99.47±6.97)%和(95.66±7.72)%,各浓度之间无显著性差异(F=0.79,P=0.5383).单纯激光辐射,其剂量为6.25、12.5、25.0、50.0、100.0 J/cm2时的细胞生存率也无显著性差异(F=0.61,P=0.6551).结论在较低的浓度范围内,5-ALA介导的光动力学治疗对人胃癌MGC-803细胞的杀伤作用随着5-ALA浓度的增加而增加,在较高浓度时则存在饱和现象,杀伤力与光剂量成正比.单纯激光不能产生光动力效应,5-ALA本身对细胞无毒性作用.5-ALA介导的光动力学治疗是很有希望的胃癌治疗方法.

Effect of photodynamic therapy with 5-aminolevulinic acid on human gastric cancer cells in vitro

Objective To investigate the effect of 5-aminolevulinic acid(5-ALA)-mediated photodynamic therapy(PDT) on MGC-803 human gastric cancer cells in vitro.Methods MGC-803 human gastric cancer cells were treated with 5-ALA at various concentrations followed by laser irradiation.The cells were also treated with 5-ALA at the same concentration before laser exposure at various doses.PDT-induced phototoxicity of the cells was determined by MTT assay.Results After laser exposure of the cells at the same dose(25.0 J/cm2),the cell survival rates decreased significantly with incubation of the cells with 5-ALA at 0.25,0.5,1.0,2.0 and 4.0 mmol/L,respectively(F=266.39,P<0.001),but 2.0 and 4.0 mmol/L ALA showed no significant difference in lowering the cell survival rates(P>0.05).Following treatment with the same 5-ALA concentration(1 mmol/L),the cell survival rates decreased in response to increased laser doses(at 6.25,12.5,25.0,50.0,and 100 J/cm2,respectively,F=226.31,P<0.0001).Without laser exposure,the survival rate of the cells did not significantly change for different 5-ALA concentrations(F=0.79,P=0.5383),nor did it undergo obvious variation in response to different laser doses without 5-ALA incubation(F=0.61,P=0.6551).Conclusions The damage of MGC-803 cells by PDT increases with 5-ALA concentration within a relative lower range and is proportional to the laser doses delivered.Without 5-ALA treatment,the laser at the chosen dose cannot produce photodynamic effect and ALA itself is nontoxic.ALA-mediated PDT appears to be a promising therapy for gastric cancer.