褪黑素对体外培养的视网膜母细胞瘤HXO-RB44细胞增生活性的影响察

目的 探讨褪黑素（MLT）对视网膜母细胞瘤(RB)HXO-RB44细胞增生活性的影响及相关机制。方法 利用四氮唑化合物（MTT）比色法，观察不同浓度的MLT对RB HXO-RB44细胞增生活性的影响；利用10-10、10-9、10-8、10-7 mmol/L的MLT对RB HXO-RB44分别进行干预，采用Hoechst荧光染色观察细胞凋亡的形态学变化；利用流式细胞仪测定不同浓度的MLT干预24 h后，RB HXO-RB44细胞内活性氧（ROS）的表达、细胞周期与凋亡情况。结果 浓度为10-7 mmol/L以下的MLT对HXO-RB44细胞并无抑制作用（P值均＞0.05）。10-6 mmol/L以上的MLT能够显著抑制HXO-RB44细胞增生（P＜0.01）。浓度为10-6、10-5、10-4 mmol/L的MLT干预后，随药物浓度的升高，HXO-RB44细胞内ROS的表达逐渐升高。Hoechst染色显示：不同浓度的褪黑素分别作用于培养的HXO-RB44细胞4、8、12、24 h后，细胞核固缩、核碎裂增多，细胞凋亡的程度随着MLT浓度的增大而加重。流式细胞仪检测：药物干预后，G0/G1期细胞明显增多，S期细胞减少，G2/M期细胞相对增多，随着MLT浓度的升高，HXO-RB44细胞凋亡率明显升高。结论 浓度大于10-6 mmol/L的MLT能够有效地抑制HXO-RB44细胞增生，其抑制效率随药物浓度的升高和作用时间的延长而增强；MLT的抗细胞增殖作用可能与其诱导HXO-RB44细胞内的活性氧产生、阻滞细胞周期于G0/G1期并诱导细胞凋亡有关。

The effects of melatonin on the proliferative activity of retinoblastoma cell line HXO-RB44

Objective To investigate inhibited effects of melatonin (MLT) on proliferative activity of retinoblastoma cell line HXO-RB44 and its related mechanism. Methods HXO-RB44 cells were treated by MLT of different concentration (10-10, 10-9, 10-8, 10-7 mmol/L. Cell counting and tetrazolium dye-reduction assay (MTT) were used to determine the effect of MLT on the survival and proliferation of HXO-RB44 cells. Apoptotic nuclei were further analyzed by Hoechst-PI fluorescence staining. Flow eytometry was used to measure the fluorescent intensity of ROS, cell cycle distribution and apoptosis. Results 10-6 mmol/L (or exceed) of MLT could inhibit the proliferation of HXO-RB44 cells in vitro while 10-7 mmol/L (or below) of MLT couldn't. With the increase of MLT concentration from 10-10 mmol/L to 10-7mmol/L, HXO-RB44 cells gradually increased the expression of ROS. Hoechst staining showed that 4, 8, 12 and 24 hours after the incubation with MLT, the nuclear pyknosis and nuclear fragmentation increased in HXO-RB44 cells. The extent of apoptosis was proportional to the concentrations of MLT. Flow cytometry revealed that with the increasing of MLT concentration, G0/G1and G2/M phase cells increased, S phase cells decreased. The apoptotic rate was also increased. Conclusion 10-6 M of MLT could inhibit the proliferation of HXO-RB44 cells. This effect may relate to the increased ROS expression, cell cycle arrest at G0/G1phase and apoptosis of HXO-RB44 cells.