Department of Gastroenterology, PLA. The Military General Hospital of Beijing, Beijing, China.
J Dig Dis. 2012 Mar;13(3):143-152. doi: 10.1111/j.1751-2980.2011.00563.x.
In previous studies cellular prion protein (PrPc) is confirmed to be involved in multidrug resistance (MDR) of gastric cancer. Although octarepeat peptides are important functional domains of PrPc and are closely related to the transport of Cu2+/Zn2+ and antioxidative function, the significance in MDR remains unknown. We aimed to investigate the role of octarepeat peptides in gastric cancer MDR.
Small interfering RNA (siRNA) against PrPc were transfected into adriamycin-resistant gastric cancer cell lines to inhibit the expression of wild type PrPc, and then constructs encoding PrPc without octarepeat peptides and PrPc without the fifth repeat peptide were transfected, respectively, to establish the cell models. In vitro drug sensitivity, cell apoptosis, measurement of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (GSH), as well as changes in glutathione S-transferase (GST) were detected.
In vitro drug sensitivity test showed that octarepeat peptides could modulate the drug resistance of gastric cancer cells, but the deletion of the fifth repeat peptide had no effect. Specifically, the anti-apoptotic capacity of gastric cancer cells decreased significantly when the octarepeat peptides of PrPc was absent. Moreover, the activities of total SOD, Cu2+/Zn2+-SOD, GSH-Px, GSH, and GST detected in different stressing periods revealed that cells lacking octarepeat peptides of PrPc exhibited weakened responses to stress. However, absence of the fifth repeat peptide did not exert any effect on stress response.
The octarepeat peptides of prion is responsible for MDR in gastric cancer cells while the fifth repeat peptide is not.
在之前的研究中已证实细胞朊蛋白（PrPc）参与胃癌多药耐药（MDR）。尽管八重复肽是 PrPc 的重要功能域，与 Cu2+/Zn2+的转运和抗氧化功能密切相关，但它们在 MDR 中的意义尚不清楚。本研究旨在探讨八重复肽在胃癌 MDR 中的作用。
用小干扰 RNA（siRNA）转染阿霉素耐药胃癌细胞系，抑制野生型 PrPc 的表达，然后分别转染不含八重复肽和不含第 5 重复肽的 PrPc 构建体，建立细胞模型。检测细胞的体外药物敏感性、细胞凋亡、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）和谷胱甘肽（GSH）的测定，以及谷胱甘肽 S-转移酶（GST）的变化。
体外药敏试验表明，八重复肽可调节胃癌细胞的耐药性，但缺失第 5 重复肽则无影响。具体来说，当 PrPc 的八重复肽缺失时，胃癌细胞的抗凋亡能力显著下降。此外，在不同应激期检测到的总 SOD、Cu2+/Zn2+-SOD、GSH-Px、GSH 和 GST 的活性表明，缺乏 PrPc 八重复肽的细胞对应激的反应能力减弱。然而，缺失第 5 重复肽对应激反应没有影响。
朊蛋白的八重复肽负责胃癌细胞的 MDR，而第 5 重复肽则不负责。
