Oncolytic effects of a novel influenza A virus expressing interleukin-15 from the NS reading frame.

Marijke Van Rikxoort,Thomas Muster,Hans Wilhelm Doerr,Markus Wolschek,Martin Michaelis,Andrej Egorov,Joachim Seipelt,Jindrich Cinatl,Brian Lichty

doi:10.1371/journal.pone.0036506

Marijke Van Rikxoort, Thomas Muster + Show 7 more

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https://doi.org/10.1371/journal.pone.0036506

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Journal: PloS one	Publication Date: May 1, 2012
Citations: 72	License type: CC BY 4.0

Affiliation: Goethe University Frankfurt

Abstract

Oncolytic influenza A viruses with deleted NS1 gene (delNS1) replicate selectively in tumour cells with defective interferon response and/or activated Ras/Raf/MEK/ERK signalling pathway. To develop a delNS1 virus with specific immunostimulatory properties, we used an optimised technology to insert the interleukin-15 (IL-15) coding sequence into the viral NS gene segment (delNS1-IL-15). DelNS1 and delNS1-IL-15 exerted similar oncolytic effects. Both viruses replicated and caused caspase-dependent apoptosis in interferon-defective melanoma cells. Virus replication was required for their oncolytic activity. Cisplatin enhanced the oncolytic activity of delNS1 viruses. The cytotoxic drug increased delNS1 replication and delNS1-induced caspase-dependent apoptosis. Interference with MEK/ERK signalling by RNAi-mediated depletion or the MEK inhibitor U0126 did not affect the oncolytic effects of the delNS1 viruses. In oncolysis sensitive melanoma cells, delNS1-IL-15 (but not delNS1) infection resulted in the production of IL-15 levels ranging from 70 to 1140 pg/mL in the cell culture supernatants. The supernatants of delNS1-IL-15-infected (but not of delNS1-infected) melanoma cells induced primary human natural killer cell-mediated lysis of non-infected tumour cells. In conclusion, we constructed a novel oncolytic influenza virus that combines the oncolytic activity of delNS1 viruses with immunostimulatory properties through production of functional IL-15. Moreover, we showed that the oncolytic activity of delNS1 viruses can be enhanced in combination with cytotoxic anti-cancer drugs.

Highlights

Oncolytic viruses destroy selectively tumour cells sparing nonmalignant cells [1]
The oncolytic effects of the oncolytic influenza A viruses deleted non-structural protein 1 (NS1) gene (delNS1), delNS1-IL-15, and the wildtype NS1 expressing IVR-116 virus were examined in four different melanoma cell lines: Colo-679, MeWo, IGR-39, and IPC298
DelNS1-IL-15 virus replicated in and induced death of interferon-defective melanoma cells to a similar extent like the non-modified delNS1 virus. These results demonstrate for the first time that the expression of foreign genes from the genome of oncolytic delNS1 viruses does not interfere with their antitumoural activity

Summary

Introduction

Oncolytic viruses destroy selectively tumour cells sparing nonmalignant (normal) cells [1]. This results in alterations of the activation status of many different signal transduction pathways, such as the Ras/ Raf/MEK/ERK or PI3K/AKT kinase pathways [2] as well as pathways involved in the antiviral response such as interferon signalling. These alterations render tumour cells susceptible to different (engineered) oncolytic viruses while normal cells are not affected by them. In order to enhance the anti-cancer properties of oncolytic viruses, so called ‘‘armed viruses’’ have been developed In addition to their oncolytic activities, these viruses encode for various gene products that exert anti-cancer effects. Other viruses encode for gene products that exert anti-angiogenic or immunostimmulatory effects [3,4,5,6]

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