Abstract 990: Improving TRAIL therapy response in pancreatic cancer by replenishment of miR-145
Authors: Setua Saini , Khan Sheema , Dan Nirnoy , Yallapu Murali M. , Kumari Sonam , Behrman Stephen W. , Jaggi Meena , Chauhan Subhash C. 
Published: August 2019

Background: Pancreatic cancer (PanCa) is a third leading cause of cancer related deaths in US. Unlike other cancers, PanCa is highly resistant to TNF-related apoptosis-inducing ligand (TRAIL) that emerges as one of the most-promising therapy in clinical trials. Our group has previously identified microRNA-145 (miR-145) is downregulated in PanCa, the restoration of which inhibits tumor growth and enhances gemcitabine sensitivity. In this study, we have observed that miR-145 restoration in PanCa cells renders them sensitive to TRAIL treatment. Therefore, we have engineered unique superparamagnetic nanoparticles (SPs) for co-delivering miR-145 and TRAIL for improving TRAIL response in PanCa cells.

Methods: PanCa cells, HPAF-II and AsPC1 were used in the study. A precipitation approach was employed to develop the SP formulation, which was conjugated with miR-145 and pEGFP-TRAIL. Particles were investigated for size, physico-chemical characterization (Dynamic light scattering) and the complexation of miR-145 and pEGFP-TRAIL by gel retardation assay. The formulation was investigated for functional assays, such as, proliferation (MTT), invasion (Matrigel), migration (Boyden chamber), colony and spheroid formation assays. Western blotting and immunofluorescence assays were used to investigate the effects of miR-145 restoration and death receptor activation in cells. The effect of nanoformulation on the tumor growth was investigated using xenograft mice model.

Results: The results in this study demonstrate that acquired resistance to TRAIL in PanCa cells can be minimized with the replenishment of miR-145 expression. Our SP nanoparticles were engineered to co-deliver miR-145 and TRAIL to PanCa cells, which resulted in simultaneous restoration of miR-145 and inhibition of acquired resistance to TRAIL. Combined actions of miR-145 and TRAIL markedly improve TRAIL-induced apoptotic effects in PanCa cells through the activation of an extrinsic apoptosis pathway as indicated by activation of DR5, FLIP, FADD and enhanced expression of caspase-8/3. The co-delivery of miR-145 and TRAIL using SP nanoparticles inhibited tumorigenic characteristics of PanCa cells, which include proliferation, invasion, migration and clonogenicity. The results were reciprocated and got further confirmed with the inhibition of tumorsphere formation and in vivo tumorigenicity in xenograft mice. Immunohistochemical staining of excised tumor tissues demonstrate an activation of death receptor pathway and subsequent expression of apoptotic markers.

Conclusion: The study provides novel insights on two facades- how resistance of cancer cells to TRAIL-based pro-apoptotic therapies can be tackled, and how efficient intracellular delivery of TRAIL can be achieved using a nanotechnology platform. Our results suggest that TRAIL resistance can be overcome by co-delivery of miR-145 and TRAIL using SP nanoparticles.

Citation Format: Saini Setua, Sheema Khan, Nirnoy Dan, Murali M. Yallapu, Sonam Kumari, Stephen W. Behrman, Meena Jaggi, Subhash C. Chauhan. Improving TRAIL therapy response in pancreatic cancer by replenishment of miR-145 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 990.