Fox Candace R, Parks Griffith D
University of Central Florida College of Medicine, Orlando, Florida, USA.
University of Central Florida College of Medicine, Orlando, Florida, USA
J Virol. 2018 Mar 14;92(7). doi: 10.1128/JVI.01948-17. Print 2018 Apr 1.
A parainfluenza virus 5 (PIV5) with mutations in the P/V gene (P/V-CPI) is restricted for spread in normal cells but not in cancer cells and is effective at reducing tumor burdens in mouse model systems. Here we show that P/V-CPI infection of HEp-2 human laryngeal cancer cells results in the majority of the cells dying, but unexpectedly, over time, there is an emergence of a population of cells that survive as P/V-CPI persistently infected (PI) cells. P/V-CPI PI cells had elevated levels of basal caspase activation, and viability was highly dependent on the activity of cellular inhibitor-of-apoptosis proteins (IAPs) such as Survivin and XIAP. In challenge experiments with external inducers of apoptosis, PI cells were more sensitive to cisplatin-induced DNA damage and cell death. This increased cisplatin sensitivity correlated with defects in DNA damage signaling pathways such as phosphorylation of Chk1 and translocation of damage-specific DNA binding protein 1 (DDB1) to the nucleus. Cisplatin-induced killing of PI cells was sensitive to the inhibition of wild-type (WT) p53-inducible protein 1 (WIP1), a phosphatase which acts to terminate DNA damage signaling pathways. A similar sensitivity to cisplatin was seen with cells during acute infection with P/V-CPI as well as during acute infections with WT PIV5 and the related virus human parainfluenza virus type 2 (hPIV2). Our results have general implications for the design of safer paramyxovirus-based vectors that cannot establish PI as well as the potential for combining chemotherapy with oncolytic RNA virus vectors. There is intense interest in developing oncolytic viral vectors with increased potency against cancer cells, particularly those cancer cells that have gained resistance to chemotherapies. We have found that infection with cytoplasmically replicating parainfluenza virus can result in increases in the killing of cancer cells by agents that induce DNA damage, and this is linked to alterations to DNA damage signaling pathways that balance cell survival versus death. Our results have general implications for the design of safer paramyxovirus-based vectors that cannot establish persistent infection, the repurposing of drugs that target cellular IAPs as antivirals, and the combined use of DNA-damaging chemotherapy agents in conjunction with oncolytic RNA virus vectors.
一种在P/V基因中存在突变的副流感病毒5型（PIV5，即P/V-CPI）在正常细胞中传播受限，但在癌细胞中不受限，并且在小鼠模型系统中能有效减轻肿瘤负担。在此我们表明，P/V-CPI感染人喉癌细胞系HEp-2会导致大多数细胞死亡，但出乎意料的是，随着时间推移，会出现一群作为P/V-CPI持续感染（PI）细胞存活下来的细胞群体。P/V-CPI PI细胞的基础半胱天冬酶激活水平升高，其活力高度依赖于细胞凋亡抑制蛋白（IAPs）如生存素（Survivin）和X连锁凋亡抑制蛋白（XIAP）的活性。在用外部凋亡诱导剂进行的挑战实验中，PI细胞对顺铂诱导的DNA损伤和细胞死亡更敏感。这种对顺铂敏感性的增加与DNA损伤信号通路的缺陷相关，如细胞周期检查点激酶1（Chk1）的磷酸化以及损伤特异性DNA结合蛋白1（DDB1）向细胞核的转位。顺铂诱导的PI细胞杀伤对野生型（WT）p53诱导蛋白1（WIP1）的抑制敏感，WIP1是一种磷酸酶，作用是终止DNA损伤信号通路。在P/V-CPI急性感染期间的细胞以及野生型PIV5和相关病毒人副流感病毒2型（hPIV2）急性感染期间的细胞中，也观察到了对顺铂的类似敏感性。我们的结果对于设计无法建立持续感染的更安全的基于副粘病毒的载体以及将化疗与溶瘤RNA病毒载体联合使用的潜力具有普遍意义。人们对开发对癌细胞，特别是那些对化疗产生抗性的癌细胞具有更强效力的溶瘤病毒载体有着浓厚兴趣。我们发现，细胞质复制的副流感病毒感染可导致诱导DNA损伤的药物对癌细胞杀伤作用增强，这与平衡细胞存活与死亡的DNA损伤信号通路改变有关。我们的结果对于设计无法建立持续感染的更安全的基于副粘病毒的载体、将靶向细胞IAPs的药物重新用作抗病毒药物以及将DNA损伤化疗药物与溶瘤RNA病毒载体联合使用具有普遍意义。
