Exploring baculovirus-mediated gene therapy targeting humanin in experimental CNS tumors

PIDRE, MATÍAS L.; GOTTARDO, MARÍA FLORENCIA; ABRIL MARCHESINI; ZUCCATO CAMILA; ASAD ANTONELLA; MA. LAURA PÉREZ VIDAKOVICS; NICOLA CANDIA, ALEJANDRO JAVIER; SOFÍA SAGRIPANTI; CANDOLFI M; SEILICOVICH, ADRIANA; ROMANOWSKI VICTOR

Congreso; XV Congreso Nacional de Virología; 2019

Spanish Society for Virology

AcMNPV, the prototype baculovirus, does not infect vertebrates, but can efficiently transduce DNA in a wide variety of cells. Humanin (HN) is a mitochondrial-derived peptide that plays a cytoprotective role in several cell types and also promotes autophagy. We have previously shown that inhibition of endogenous HNr (a rat homolog of human HN) expression induces apoptosis in a pituitary somatolactotrope tumor cell line (GH3) using a shRNA against HN/HNr delivered by a recombinant AcMNPV (Ac-shHNr). Ac-shHNr also expresses dTomato as a reporter gene. Moreover, intratumor injection of Ac-shHNr reduced tumor growth of GH3 mouse tumor models and increased their survival. In this study we further evaluated the use of AcMNPV for transgene delivery in tumors of the CNS, i.e. experimental prolactinoma and glioblastoma (GB) by exploring transduction efficiency, neurotoxicity, apoptosis and autophagy induction. Materials & MethodsNude mice were injected subcutaneously (s.c.) with 3 × 106 GH3 cells, and C57BL/6 mice were injected intracraneally (i.c.) with 2x104 syngeneic GL26 GB cells. Three weeks after inoculation, animals were injected intratumorally with 108 PFUs of recombinant or control baculovirus for pituitary tumors or 109 PFUs for glioblastoma. Naïve mice were also injected in the brain to assess neurotoxicity. Transduction efficiency (dTomato), apoptosis (TUNEL) and autophagy induction (immunofluorecence) were assessed after 5 or 15 days. HN expression and effect on chemosensitivity were also determined after transduction of GB cells in vitro.ResultsWe detected AcMNPV-mediated expression of reporter and HN genes in the naïve brain and the intracranial tumors without signs of neurotoxicity. Ac-shHNr induced apoptosis and increased the sensivity of GB cells to chemotherapeutic drugs cisplatin and temozolomide. Local injection of Ac-shHNr increased the apoptotic rate in GH3 tumors. Finally, we determined that Ac-shHNr treatment decreased expression levels of LC3 and ATG17, suggesting that Ac-shHNr can also inhibit autophagy in pituitary tumors. Discussion & ConclusionOur results suggest that silencing of endogenous HN using baculoviral vectors induces apoptosis of tumor cells, leading to inhibition of tumor growth. Therefore, the use of baculovirus vectors could be a promising alternative and a complement for the treatment of tumors of the CNS.