ALA-PDT对SW480结肠癌细胞周期阻滞作用及对G_1/S关卡调控因子的影响

Involvement of G_1/S checkpoint regulators during photodynamic-therapy-mediated cell cycle arrest in human colon carcinoma SW480 cells

目的:了解光动力疗法对结肠癌SW480细胞的周期阻滞作用与G1/S关卡调控因子之间的联系. 方法:对体外培养的SW480结肠癌细胞进行ALA-PDT实验,使用流式细胞仪技术观测基于δ-氨基乙酰丙酸的光动力疗法对SW480细胞的细胞周期阻滞作用,应用免疫细胞化学技术检测光动力疗法对G1/S关卡调控因子Chk2,P21wAF1/Cip1/Sdi1,CyclinD1蛋白表达的影响. 结果:基于δ-氨基乙酰丙酸的光动力疗法可在其作用后早期诱导SW480细胞产生G0-G1细胞周期阻滞,G0/G1期比例显著增加,而S期和G2/M期比例明显下降,且呈时间依赖性变化;光动力作用诱导SW480细胞G1/S关卡调控因子Chk2,P21wAF1/Cip1/Sdi1蛋白表达增高,降低CyclinD1 蛋白表达,与G1/S期阻滞进程相一致,均呈时间依赖性变化. 结论:基于δ-氨基乙酰丙酸的光动力疗法可诱导SW480 细胞产生G0-G1细胞周期阻滞,光动力疗法对SW480细胞的G0-G1期阻滞作用与其对多个G1/S关卡调控因子的调节事件有关.

AIM: To investigate the involvement of G1/S regulators during ALA-PDT-mediated cell cycle arrest. METHODS: Colon carcinoma SW480 cells were treated with 1 mmol/L ALA and 6 h later irradiated with 9 J/cm2 631 nm light from a laser. The analysis of cell cycle arrest by ALA-PDT was performed by flow cytometry. The effect of ALA-PDT on G1/S cell cycle regulators Chk2, CyclinD1 and P21WAF1/Cip1/Sdi1 was examined by using immunocy-tochemical technique. RESULTS: ALA-PDT resulted in G0-G1 phase arrest of the tumor cell cycle in post-PDT in a time-dependent manner. Immunocytochemical analysis revealed that PDT resulted in an induction of G1/S checkpoint regulation factors such as Chk2 and P21WAF1/Cip1/Sdi1, and a down-regulation of CyclinD1 in a time-dependent manner. CONCLUSION: ALA-PDT causes G0-G1 phase arrest of SW480 cell cycle in post-PDT earlier period; PDT-medi-ated induction of G1/S checkpoint regulators Chk2 and P21WAF1/Cip1/Sdi1 results in the imposition of artificial checkpoint at G1-S checkpoint thereby leading to an arrest of cells in G0-G1 phase of the cell cycle through inhibition in cyclinD1 in a time-dependent manner.