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

• Published in: PloS one Vol. 7; no. 5; p. e36506
• Main Authors: van Rikxoort, Marijke, Michaelis, Martin, Wolschek, Markus, Muster, Thomas, Egorov, Andrej, Seipelt, Joachim, Doerr, Hans Wilhelm, Cinatl, Jr, Jindrich
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.05.2012; Public Library of Science (PLoS)
• Subjects: Amino Acid Chloromethyl Ketones - pharmacology; Amino acids; Analysis; Animals; Antineoplastic Agents - pharmacology; Apoptosis; Apoptosis - drug effects; Avian flu; Biological response modifiers; Biology; Biotechnology; Blotting, Western; Cancer; Caspase; Caspase Inhibitors; Caspases - metabolism; Cell culture; Cell Line, Tumor; Cell Survival - drug effects; Cells, Cultured; Chemokines; Chlorocebus aethiops; Cisplatin; Cisplatin - pharmacology; Cysteine Proteinase Inhibitors - pharmacology; Cytokines; Cytotoxicity; Drugs; Extracellular signal-regulated kinase; Gene Deletion; Genes; Health aspects; Heat shock proteins; Humans; Immunostimulation; Infection; Infections; Influenza; Influenza A; Influenza A virus; Influenza A Virus, H1N1 Subtype - genetics; Influenza A Virus, H1N1 Subtype - growth & development; Influenza viruses; Interferon; Interleukin; Interleukin 15; Interleukin-15 - genetics; Interleukin-15 - metabolism; Interleukins; Killer cells; Kinases; Language; Lysis; Medicine; MEK inhibitors; Melanoma; Melanoma - genetics; Melanoma - pathology; Melanoma - virology; Metastasis; Mitogen-Activated Protein Kinase 1 - genetics; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - genetics; Mitogen-Activated Protein Kinase 3 - metabolism; Mutation; Natural killer cells; NS1 protein; Oncolysis; Oncolytic Viruses - genetics; Oncolytic Viruses - growth & development; Pandemics; Raf protein; Ras protein; Replication; RNA Interference; RNA-mediated interference; Signal transduction; Signaling; Tumors; Vero Cells; Viral Nonstructural Proteins - genetics; Virus Replication - drug effects; Viruses; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0036506

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.