Abstract PR09: Polymeric mechanical amplifiers of tumor apoptosis

Abstract

Abstract Regulation of receptor-mediated phenomenon at the nanoscale in a controlled manner remains a challenge for a broad range of fields, including cell biology, medicine, and bioengineering. Fluid forces play a crucial role in receptor-mediated signaling necessary for physiological function, while materials such as nanoparticles have demonstrated potential for spatiotemporal control of cellular signaling. Here, we have developed polymeric mechanical amplifiers that tether to the cell surface and increase receptor-mediated apoptosis in the presence of physiological fluid flow. The mechanical amplifiers consist of both non-degradable and biodegradable polymer nanoparticles that are tethered to the surface of tumor cells via polyethylene glycol (PEG) linkers. Tethered nanoparticles, in the presence of fluid shear forces observed in vivo, increased the therapeutic effect of a TNF superfamily death ligand (TRAIL) on colon and prostate tumor cells by as much as 50% compared to soluble TRAIL treatment alone, while exerting negligible toxic effects on normal cells. Increasing the number of nanoparticles conjugated to the tumor cell surface enhanced TRAIL-mediated apoptosis under fluid shear exposure, while the therapeutic effect under static conditions was not altered. Our results suggest that the enhanced therapeutic response using polymeric nanoparticles is both receptor-mediated apoptosis-specific and does not affect doxorubicin efficacy. Inhibition studies indicate the response is caspase signaling-dependent, and increased tumor cell death receptor expression in the presence of shear forces is also observed. We show that targeted polymeric nanoparticles delivered to tumor cells in vivo mechanically amplified a subsequent treatment of soluble TRAIL, and reduced both circulating tumor cells in blood and overall tumor cell burden in vivo by over 90%. We conclude that surface-bound polymeric nanoparticles enhance receptor-mediated apoptosis in the presence of physiological shear forces, and represents a potentially new application for a broad range of nanotechnologies to maximize the capacity of receptor-mediated signaling and function in the presence of a ligand. This abstract is also being presented as Poster B35. Citation Format: Michael John Mitchell, Robert Langer. Polymeric mechanical amplifiers of tumor apoptosis. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr PR09.