Abstract 3948: Simultaneousin vivoPTEN rescue and KRAS silencing in cancer therapy

Background : The tumor suppressor PTEN and the KRAS oncogene play essential roles in tumorigenesis. PTEN mutations and resulting loss of function are common across variety of tumors and influence tumor cell proliferation. KRAS mutations occur in > 40% of cancer and have been associated with increased tumorigenicity. In numerous cancers, cooperative interactions between KRAS mutations and PTEN loss have been reported to promote metastatic development. However, to date there is no effective treatment for inhibiting KRAS activity or rescuing PTEN function in cancers. We investigated a new technique for simultaneous PTEN rescue and silencing of KRAS that may have therapeutic potential in PTEN/KRAS mutated pancreatic and other cancers. Methods : ADGN-technology is based on short amphipathic peptides that form stable neutral nanoparticles through non-covalent electrostatic and hydrophobic interactions with a large panel of nucleic acids. Self-assembled ADGN/nucleic acid nanoparticles remain stable over time in serum and plasma conditions. ADGN peptide complexes with wt PTEN mRNA or siRNA targeting KRAS were evaluated on pancreas (PANC1), ovarian (SKOV3), prostate (PC3) and glioblastoma (U25) cell lines. PTEN, KRAS and AKT phosphorylation were evaluated by western blot. Cell proliferation and apoptosis activation were determined by flow cytometry and Tunel assay. In-vivo Efficacy of IV-administered ADGN-peptides complexed with PTEN mRNA (0.25 mg/kg) and/or KRAS siRNA (0.5 mg/kg) was tested in PANC1-LUC mouse xenografts. Cytokine response to ADGN-nucleic acid complexes were measured in blood samples using Luminex cytokine 20 plex. Results : ADGN-mediated delivery of wt PTEN mRNA, rescued PTEN function in the cell-lines tested. Restoring PTEN resulted in ~90% reduction of cell proliferation, 3-8 fold activation of cell apoptosis, reduction of AKT phosphorylation and cell cycle arrest in G1. ADGN-nanoparticles containing wt PTEN mRNA resulted in tumor growth inhibition (TGI) of 80%. ADGN-mediated delivery of siRNA targeting KRAS, induced knock-down of KRAS expression by 60-70% in the cell-lines and significantly reduced viability by 50-70%. ADGN-nanoparticles containing siRNA KRAS resulted in a TGI of 50%. Combination mRNA PTEN and siRNAs KRAS ADGN nanoparticles, resulted in a TGI of 90% in PANC1 xenografts and also slowed development of distant metastates. No nonspecific cytokine response was observed following administration of ADGN-nucleic acid complexes.Conclusions: ADGN-peptides complexed with mRNA and/or siRNA were effective in targeting mutated PTEN and KRAS both invitro and invivo. This suggests a new strategy for targeting both tumor suppressors and oncogenes. Citation Format: Gilles Divita, Veronique Josserand, Melanie Guidetti, Neil Desai. Simultaneous in vivo PTEN rescue and KRAS silencing in cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3948.