Biophysical Society Conference | Estes Park 2023

Membrane Budding and Fusion

Tuesday Speaker Abstracts

SENSITIZATION OF CANCER CELLS TO FAS-INDUCED APOPTOSIS THROUGH ENDOCYTOSIS INHIBITION

Comert Kural 1 ; 1 Ohio State University, Physics, Columbus, OH, USA

Fas (CD95/APO-1) is a transmembrane death receptor that transmits apoptotic signals upon binding its ligand and forming a death-inducing signaling complex (DISC). The intracellular trafficking of Fas receptors, including their recycling from endosomes to the plasma membrane, plays a crucial role in the ligand-induced assembly of DISC. Despite being highly expressed in tumor cells, insufficient expression of these receptors on the cell surface renders cancer cells insensitive to Fas-induced apoptosis. In this study, we demonstrate that inhibiting endocytosis enhances the formation of Fas microaggregates on the plasma membrane, thereby sensitizing cancer cells to Fas-induced apoptosis. We have identified Fasudil, a vasodilator widely used in clinical practice, which effectively slows down endocytosis by increasing plasma membrane tension. In combination with exogenous soluble Fas ligand (sFasL), Fasudil significantly enhances apoptosis in cancerous cells, while exhibiting a notably weaker synergistic effect in nonmalignant cells. Furthermore, the combination of sFasL and Fasudil effectively impedes the growth of glioblastoma cells in embryonic stem cell-derived brain organoids and induces tumor regression in a xenograft U87 tumor model in nude mice. These findings underscore the strong potential of sFasL treatment as an apoptosis-directed cancer therapy when the formation of Fas microaggregates is augmented through the inhibition of endocytosis dynamics. Wenting Zhao 1,2 ; Huanwen Mu 1 ; Xinwen Miao 1 ; Xiangfu Guo 1 ; 1 Nanyang Technological University, School of Chemistry, Chemical Engineering and Biotechnology, Singapore, Singapore 2 Nanyang Technological University, Institute for Digital Molecular Analytics and Science (IDMxS), Singapore, Singapore Cellular processes induce significant topographical changes in the membrane components of a cell, including the plasma membrane and nuclear envelope. However, visualizing these changes, which often occur on the scale of tens to hundreds of nanometers, can be physically challenging. In this talk, we will present our work in developing patterns of vertically-aligned nanostructures as a tool to generate pre-defined membrane topography both in live cells and in vitro using synthetic lipid or cell-derived membrane vesicles. We will demonstrate examples of topography guided assembly of membrane-associated proteins and lipids, and discuss their connection to diseases. Specifically, we will explore the use of topography engineering to study curvature guided membrane clustering of oncogenic Ras proteins, preferential assembly of viral non structural proteins for viral replication complex formation, and adhesion complex reorganization and protein condensation in immune cells. These studies shed light on how cells generate and control small-scale deformations to harbor or facilitate functional assemblies and pave the way to more comprehensive understanding of membrane geometry control in cells under physiological and pathological conditions. NANOSCALE MEMBRANE TOPOGRAPHY ENGINEERING: IN CELLS, IN VITRO AND IN BETWEEN

32