Department of Medicine, Cancer Therapy and Research Center, Institute for Drug Development, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
Cell Death Dis. 2013 Jul 18;4(7):e728. doi: 10.1038/cddis.2013.259.
Activating mutation of KRas is a genetic alteration that occurs in the majority of pancreatic tumors and is therefore an ideal therapeutic target. The ability of reoviruses to preferentially replicate and induce cell death in transformed cells that express activated Ras prompted the development of a reovirus-based formulation for cancer therapy called Reolysin. We hypothesized that Reolysin exposure would trigger heavy production of viral products leading to endoplasmic reticular (ER) stress-mediated apoptosis. Here, we report that Reolysin treatment stimulated selective reovirus replication and decreased cell viability in KRas-transformed immortalized human pancreatic duct epithelial cells and pancreatic cancer cell lines. These effects were associated with increased expression of ER stress-related genes, ER swelling, cleavage of caspase-4, and splicing of XBP-1. Treatment with ER stress stimuli including tunicamycin, brefeldin A, and bortezomib (BZ) augmented the anticancer activity of Reolysin. Cotreatment with BZ and Reolysin induced the simultaneous accumulation of ubiquitinated and viral proteins, resulting in enhanced levels of ER stress and apoptosis in both in vitro and in vivo models of pancreatic cancer. Our collective results demonstrate that the abnormal protein accumulation induced by the combination of Reolysin and BZ promotes heightened ER stress and apoptosis in pancreatic cancer cells and provides the rationale for a phase I clinical trial further investigating the safety and efficacy of this novel strategy.
KRas 激活突变是一种在大多数胰腺肿瘤中发生的遗传改变，因此是一个理想的治疗靶点。呼肠孤病毒能够优先在表达激活 Ras 的转化细胞中复制并诱导细胞死亡，这促使人们开发了一种名为 Reolysin 的基于呼肠孤病毒的癌症治疗制剂。我们假设 Reolysin 暴露会引发大量病毒产物的产生，导致内质网 (ER) 应激介导的细胞凋亡。在这里，我们报告 Reolysin 处理刺激了选择性呼肠孤病毒复制，并降低了 KRas 转化的永生化人胰腺导管上皮细胞和胰腺癌细胞系的细胞活力。这些效应与 ER 应激相关基因表达增加、ER 肿胀、半胱天冬酶-4 的切割和 XBP-1 的剪接有关。用 ER 应激刺激物（包括衣霉素、布雷菲德菌素 A 和硼替佐米 (BZ)）处理增强了 Reolysin 的抗癌活性。BZ 和 Reolysin 的共同处理诱导了泛素化和病毒蛋白的同时积累，导致胰腺癌细胞中 ER 应激和细胞凋亡水平增强，无论是在体外还是体内的胰腺癌模型中。我们的综合结果表明，Reolysin 和 BZ 的组合诱导的异常蛋白积累促进了胰腺癌细胞中的 ER 应激和细胞凋亡，并为进一步研究这种新策略的安全性和疗效的 I 期临床试验提供了依据。
