Abstract LB-060: A novel target for genetic silencing of AXL mediates taxane resistance, invasion, and migration in uterine cancer

Abstract

Abstract Objectives: We investigated the role of AXL expression in chemotherapy response in uterine papillary serous cancer, and sought to reverse chemoresistance through inactivation of AXL. Methods: In vitro cell viability (XTT) assays were performed to confirm response to chemotherapy in AN3CA (taxane sensitive) and ARK1 (taxane resistant) uterine cell lines. AXL knockdown by siRNA was performed with either a traditional transfection reagent (DharmaFECT) or with a novel serum-stable, cell-penetrating, endosomolytic amphipathic peptide delivery system (p5RHH). Following knockdown of AXL using siRNA and p5RHH, chemotherapy response was assessed by XTT assay and invasion and migration assays were performed. Cell viability assays were analyzed using multiple t-tests. P < 0.05 was considered statistically significant. Results: Expression of AXL was found to be associated with a worse prognosis in uterine cancer. Chemoresistance was validated with XTT assays for AN3CA and ARK1. Western blotting confirmed over-expression of AXL in the chemoresistant cell line, and lack of AXL expression in its chemosensitive counterparts. Reversal of paclitaxel resistance was achieved in ARK1 cells genetically by silencing AXL with shRNA. The novel delivery system, p5RHH, combined to siAXL, was shown to inactivate AXL in ARK1 cells at the RNA and protein level to a similar extent as traditional transfection technique (8.4-fold vs 8.7-fold decrease for RNA, respectively; 67% vs 83% knockdown at 48h and 84% vs 97% knockdown at 96 hours for protein, respectively). Reversal of paclitaxel resistance was achieved in ARK1 cells therapeutically and genetically using the p5RHH-siAXL complex. With AXL silencing using the p5RHH-siAXL complex, tumor cell invasion was inhibited by greater than 40%, and tumor cell migration was inhibited by greater than 60%. Conclusions: AXL expression is associated with chemoresistance in a uterine papillary serous cancer cells. Genetic inactivation of AXL in a taxane-resistant uterine cancer cells reverses chemoresistance. A novel siRNA nano-particle delivery system was successfully utilized to mimic genetic inactivation resulting in improved chemotherapy response and decreased invasion and migration. Citation Format: Marguerite Palisoul, Mai Nguyen, Hua Pan, Anne Lohrey, Samuel Wickline, Matthew Powell, David Mutch, Katherine Fuh. A novel target for genetic silencing of AXL mediates taxane resistance, invasion, and migration in uterine cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-060.