Antineoplastic Cytotoxicity and Immune Adjuvancy of a Recombinant Oncolytic Poliovirus

Our group has pioneered the development of a live-attenuated poliovirus, called PVSRIPO, for the purpose of targeting cancer. Despite clinical progress, the cancer selective cytotoxicity and immunotherapeutic potential of PVSRIPO has not yet been mechanistically dissected. Defining such mechanisms may inform its clinical application.

Herein I describe the discovery of a mechanism by which the MAP-Kinase Interacting Kinases (MNKs) regulate PVSRIPO cytotoxicity in cancer. In doing so, I delineate a novel, intricate network connecting the MNK and mTOR signaling pathway that regulates activity of a splicing kinase called the Ser-Arg Rich Protein Kinase (SRPK), and define SRPK as an impediment to IRES mediated translation. Moreover, I demonstrate that MNK regulates mTORC1 associations that determine its substrate proximity and thus, activity. In a collaborative effort, we found that PVSRIPO oncolysis produces antigen specific, cytolytic anti-tumor immunity in an in vitro human system and that much of the observed adjuvancy is due to the direct infection of dendritic cells (DCs) by the virus itself; implicating PVSRIPO as a potent adjuvant. In summary, oncogenic signaling in part through MNK leads to cancer specific cytotoxicity by PVSRIPO that engages an inflammatory environment conducive to DC activation and antigen specific T cell antigen immunity.