中文摘要：

背景与目的：SYUIQ-5是具有吲哚和喹啉结构的白叶藤碱衍生物，已有报道它能稳定和诱导G-四链体形成，抑制c—myc启动子和端粒酶活性。本实验主要研究SYUIQ-5对鼻咽癌细胞自噬的诱导作用及其机制。方法：用免疫印迹法检测SYUIQ-5处理前后鼻咽癌细胞株CNE1、CNE2和HONE1中微管相关蛋白轻链3（microtubule-associated protein 1 light chain3，LC3）、Akt、p-Akt以及自噬相关基因BNIP3（Bcl-2／adenocarcinoma E1819KD interacting protein 3）和Beclin1的蛋白表达水平。用逆转录-聚合酶链反应（RT—PCR）法检测鼻咽癌细胞中LC3和BNIP3的mRNA水平。用siRNA干扰BNIP3，检测BNIP3在SYUIQ-5诱导自噬过程中的作用。用共聚焦免疫荧光法观察FOXO3a的定位。结果：用0．25～2．0μ g／mL的SYUIQ-5处理鼻咽癌细胞CNE1、CNE2和HONE148h，其LC3的表达在蛋白和mRNA水平均明显增强，且呈浓度依赖性。SYUIQ-5能显著抑制CNE2细胞的p-Akt水平，总的Akt表达基本无变化。用3μg／mL SYUIQ-5作用CNE2细胞24h后，共聚焦免疫荧光观察可见FOXO3a由细胞浆移位到细胞核。SYUIQ-5处理的鼻咽癌细胞中自噬相关基因BNIP3蛋白显著增加，而Beclin1无明显变化。用siRNA干扰BNIP3表达后，SYUIQ-5诱导的LC3-II形成的功能受到抑制。结论：SYUXQ-5可能通过抑制Akt的激活，诱导FOXO3a移位到胞核，从而促进LC3的转录，诱导肿瘤细胞发生自噬性死亡。BNIP3也参与了SYUIQ-5诱导细胞自噬的过程。

英文摘要：

Background and Objective. As a new cryptolepine derivative containing indole and quinoline structures, SYUIQ-5 has been reported to induce and stabilize G-quadruplex, inhibit c-myc promoter and telomerase activity. This study was to investigate autophagy induced by a G-quadruplex ligand SYUIQ-5 and its mechanisms in nasopharyngeal cancer cells. Methods. The protein levels of microtubule-associated protein 1 light chain 3 （LC3）, Akt, p-Akt, autophagy-related genes BNIP3 （adenocarcinoma E1B19KD interacting protein 3） and Beclin1 were determined by Western blot in nasopharyngeal cancer cell lines CNE1, CNE2 and HONE1. The mRNA levels of LC3 and BNIP3 were detected using reverse transcription polymerase chain reaction （RT-PCR）. RNA interference was used to block the expression of BNIP3 and the effect of BNIP3 was evaluated in SYUIQ-5-induced autophagy. The localization of FOXO3a was observed using confocal immunofluorescence. Results. The protein and mRNA levels of LC3 in CNE1, CNE2 and HONE1 were up-regulated in a dose-dependent manner after being treated with 0.25-2μg/mL SYUIQ-5 for 48 h. Incubation of CNE2 cells with SYUIQ-5 markedly inhibited the phosphorylation of Akt, but did not statistically change the total Akt level. After incubation with 3μg/mL SYUIQ-5 for 24 h, nuclear translocation of FOXO3a was observed under confocal immunofluorescence in CNE2 cells. Autophagy-related gene BNIP3 was significantly elevated in nasopharyngeal cancer cells, whereas Beclinl was not significantly changed. Knockdown of BNiP3 expression using small interfering RNA caused LC3-11 down-regulation. Conclusion： SYUIQ-5 induces autophagy in cancer cells. This may be related to SYUIQ-5-mediated p-Akt down-regulation and FOXO3a nuclear translocation, which promot LC3 transcription. BNIP3 is involved in SYUIQ-5 induced autophagy.