Parainfluenza Virus Infection Sensitizes Cancer Cells to DNA-Damaging Agents: Implications for Oncolytic Virus Therapy

Abstract

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.

Cytotoxicity, cellular uptake and apoptotic responses in human coronary artery endothelial cells exposed to ultrasmall superparamagnetic iron oxide nanoparticles

“…DNase I treatment conditions (15 U, 35 minutes at room temperature) used in this study resulted in DAPI‐stained nuclei in some cells. This result is comparable with other studies using similar DNase treatment conditions (Fox, Parks, & Dutch, ; Lebon et al, ; Zhang et al, ).…”

Histone Deacetylase Inhibitors Enhance Cell Killing and Block Interferon-Beta Synthesis Elicited by Infection with an Oncolytic Parainfluenza Virus

“…While at this point it is unclear how HDAC inhibitors promote P/V-CPI-medicated increases in caspases, there is a potential mechanism linked to scriptaid-induced decreases in cellular inhibitors of apoptosis. This is supported by our previous findings that expression of cIAP-1, XIAP, and survivin are all decreased by P/V-CPI- infection and that chemical inhibition of survivin (with YM155) or XIAP (with Embelin) enhanced killing of a P/V-CPI- persistently infected cell line [26].…”

“…We have previously shown that infection with the cytoplasmic-replicating RNA virus P/V-CPI-can sensitize airway cancer cells to chemotherapeutic DNA damaging agents through the modulation of DNA damage response pathways [26]. This prior finding led us to test the hypothesis that P/V-CPI- infection would also sensitize cancer cells to treatment with other chemotherapeutic agents that alter gene expression, DNA metabolism and stress responses.…”

“…While the P/V-CPI- virus is inherently cytopathic to cancer cells, we have recently shown that P/V-CPI- infection can sensitize cancer cells to further killing by treatment with cisplatin [26], a DNA adduct-inducing chemotherapy drug. Remarkably, infection with the cytoplasmic-replicating P/V-CPI- virus followed by cisplatin treatment led to increased damage to cellular DNA, along with enhanced caspase activation and death compared to treatment with the virus or drug alone [26]. The ability of P/V-CPI- to sensitize cells to cisplatin-induced death correlated with virus-induced defects in the cell’s ability to repair damaged DNA.…”

Inhibition of DNA Repair Mechanisms and Induction of Apoptosis in Triple Negative Breast Cancer Cells Expressing the Human Herpesvirus 6 U94

“…Impaired DNA repair machinery is likely to increase cancer cell killing by DNA-damaging chemotherapeutic drugs [50,51]. Therefore, we explored the possibility that U94 might act as a chemo-sensitizer molecule.…”