MicroRNA-Attenuated Clone of Virulent Semliki Forest Virus Overcomes Antiviral Type I Interferon in Resistant Mouse CT-2A Glioma.
Glioblastoma is a terminal disease with no effective treatment currently available. Among the new therapy candidates are oncolytic viruses capable of selectively replicating in cancer cells, causing tumor lysis and inducing adaptive immune responses against the tumor. However, tumor antiviral responses, primarily mediated by type I interferon (IFN-I), remain a key problem that severely restricts viral replication and oncolysis. We show here that the Semliki Forest virus (SFV) strain SFV4, which causes lethal encephalitis in mice, is able to infect and replicate independent of the IFN-I defense in mouse glioblastoma cells and cell lines originating from primary human glioblastoma patient samples. The ability to tolerate IFN-I was retained in SFV4-miRT124 cells, a derivative cell line of strain SFV4 with a restricted capacity to replicate in neurons due to insertion of target sites for neuronal microRNA 124. The IFN-I tolerance was associated with the viral nsp3-nsp4 gene region and distinct from the genetic loci responsible for SFV neurovirulence. In contrast to the naturally attenuated strain SFV A7(74) and its derivatives, SFV4-miRT124 displayed increased oncolytic potency in CT-2A murine astrocytoma cells and in the human glioblastoma cell lines pretreated with IFN-I. Following a single intraperitoneal injection of SFV4-miRT124 into C57BL/6 mice bearing CT-2A orthotopic gliomas, the virus homed to the brain and was amplified in the tumor, resulting in significant tumor growth inhibition and improved survival.


OBJECTIVE
Although progress has been made in development of replicative oncolytic viruses, information regarding their overall therapeutic potency in a clinical setting is still lacking. This could be at least partially dependent on the IFN-I sensitivity of the viruses used. Here, we show that the conditionally replicating SFV4-miRT124 virus shares the IFN-I tolerance of the pathogenic wild-type SFV, thereby allowing efficient targeting of a glioma that is refractory to naturally attenuated therapy vector strains sensitive to IFN-I. This is the first evidence of orthotopic syngeneic mouse glioma eradication following peripheral alphavirus administration. Our findings indicate a clear benefit in harnessing the wild-type virus replicative potency in development of next-generation oncolytic alphaviruses.
A. I. Virtanen Institute for Molecular Sciences, Department of Biotechnology and Molecular Medicine, University of Eastern Finland, Kuopio, Finland.
Miika
M
Martikainen
A. I. Virtanen Institute for Molecular Sciences, Department of Biotechnology and Molecular Medicine, University of Eastern Finland, Kuopio, Finland.
Minna
M
Niittykoski
Neurosurgery of NeuroCenter, Kuopio University Hospital, Kuopio, Finland.
Mikael
M
von und zu Fraunberg
Neurosurgery of NeuroCenter, Kuopio University Hospital, Kuopio, Finland.
Arto
A
Immonen
Neurosurgery of NeuroCenter, Kuopio University Hospital, Kuopio, Finland.
Susanna
S
Koponen
A. I. Virtanen Institute for Molecular Sciences, Department of Biotechnology and Molecular Medicine, University of Eastern Finland, Kuopio, Finland.
Maartje
M
van Geenen
Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
Markus
M
Vähä-Koskela
Department of Virology, University of Helsinki, and Helsinki University Hospital, Helsinki, Finland.
Erkko
E
Ylösmäki
Neurosurgery of NeuroCenter, Kuopio University Hospital, Kuopio, Finland.
Juha E
JE
Jääskeläinen
Department of Virology, University of Helsinki, and Helsinki University Hospital, Helsinki, Finland.
Kalle
K
Saksela
A. I. Virtanen Institute for Molecular Sciences, Department of Biotechnology and Molecular Medicine, University of Eastern Finland, Kuopio, Finland ari.hinkkanen@uef.fi.
Ari
A
Hinkkanen
D000368:Aged; D000818:Animals; D001932:Brain Neoplasms / Q000276:immunology / Q000401:mortality / Q000628:therapy* / Q000821:virology; D045744:Cell Line, Tumor; D002999:Clone Cells; D019008:Drug Resistance, Neoplasm; D005260:Female; D005786:Gene Expression Regulation; D005909:Glioblastoma / Q000276:immunology / Q000401:mortality / Q000628:therapy* / Q000821:virology; D006801:Humans; D007370:Interferon Type I / Q000235:genetics / Q000276:immunology*; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000276:immunology*; D009474:Neurons / Q000276:immunology / Q000473:pathology / Q000821:virology; D050130:Oncolytic Virotherapy / Q000379:methods; D050504:Oncolytic Viruses / Q000502:physiology*; D012672:Semliki forest virus / Q000502:physiology*; D015398:Signal Transduction; D016019:Survival Analysis; D047368:Tumor Burden; D014779:Virus Replication
D007370:Interferon Type I; C509207:MIRN124 microRNA, human; D035683:MicroRNAs