Cao Bin, Shi Qintong, Wang Wengong
Department of cardiothoracic surgery, Nanjing Drum Tower Hospital, Nanjing 210008, China.
J Thorac Dis. 2015 Apr;7(4):711-9. doi: 10.3978/j.issn.2072-1439.2015.04.01.
High expression of Sirtuin type 1 (SIRT1) exists in some cancer cells. However, it is still unclear whether SIRT1 affects the sensitivity of esophageal cancer cells to cisplatin. This study was designed to explore the relationship between SIRT1 expression and resistance of esophageal squamous cell carcinoma (ESCC) cells to cisplatin and reveal the underlying mechanism.
The tissue samples of 68 ESCC patients were collected from Nanjing Drum Tower Hospital, China. All the patients had undergone cisplatin based combination chemotherapy. The expression of SIRT1and Noxa in tissue samples were analyzed by quantitative real-time reverse PCR (qRT-PCR) and Western blot. Human ESCC cell line (ECa9706 cells) was cultured and a cisplatin-resistant subline (ECa9706-CisR cells) was established by continuous exposure to cisplatin at different concentrations. The expression of SIRT1 and Noxa in both cell lines was analyzed by qRT-PCR and Western blot. siRNA technology was utilized to down-regulate the SIRT1 expression in ECa9706-CisR cells. The influence of SIRT1 silence on sensitivity of ECa9706-CisR cells to cisplatin was confirmed using CCK-8 assay and flow cytometry. Furthermore, the level change of Noxa after SIRT1 silence in ECa9706-CisR cells was determined by qRT-PCR and Western blot.
SIRT1 and Noxa expression in chemo-resistant patients was significantly increased and decreased respectively, compared with chemo-sensitive patients. SIRT1 expression in ECa9706-CisR cells was significantly increased with a lower Noxa level, compared with normal ECa9706 cells. Cisplatin 5 µM could cause proliferation inhibition, G2/M phase arrest and apoptosis in ECa9706-CisR cells and these effects could be enhanced dramatically by SIRT1 silencing. Moreover, Noxa expression was increased after treated with SIRT1 siRNA.
Over-expression of SIRT1 may cause resistance of ESCC cells to cisplatin through the mechanism involved with Noxa expression.
1型沉默调节蛋白（SIRT1）在某些癌细胞中高表达。然而，SIRT1是否影响食管癌细胞对顺铂的敏感性仍不清楚。本研究旨在探讨SIRT1表达与食管鳞状细胞癌（ESCC）细胞对顺铂耐药性之间的关系，并揭示其潜在机制。
收集中国南京鼓楼医院68例ESCC患者的组织样本。所有患者均接受了以顺铂为基础的联合化疗。通过定量实时逆转录PCR（qRT-PCR）和蛋白质免疫印迹法分析组织样本中SIRT1和Noxa的表达。培养人ESCC细胞系（ECa9706细胞），通过连续暴露于不同浓度的顺铂建立顺铂耐药亚系（ECa9706-CisR细胞）。通过qRT-PCR和蛋白质免疫印迹法分析两种细胞系中SIRT1和Noxa的表达。利用小干扰RNA（siRNA）技术下调ECa9706-CisR细胞中SIRT1的表达。使用细胞计数试剂盒-8（CCK-8）检测法和流式细胞术确定SIRT1沉默对ECa9706-CisR细胞对顺铂敏感性的影响。此外，通过qRT-PCR和蛋白质免疫印迹法测定ECa9706-CisR细胞中SIRT1沉默后Noxa的水平变化。
与化疗敏感患者相比，化疗耐药患者中SIRT1和Noxa的表达分别显著升高和降低。与正常ECa9706细胞相比，ECa9706-CisR细胞中SIRT1表达显著升高，Noxa水平较低。5 μM顺铂可导致ECa9706-CisR细胞增殖抑制、G2/M期阻滞和凋亡，而SIRT1沉默可显著增强这些效应。此外，用SIRT1 siRNA处理后Noxa表达增加。
SIRT1的过表达可能通过与Noxa表达相关的机制导致ESCC细胞对顺铂耐药。
