Quantitative approaches for the mechanistic analysis of tumor cell killing by cytotoxic lymphocytes

Sloan Kettering Institute For Cancer Research, New York NY

Investigators

Abstract

Cytotoxic T cells function by selectively destroying virally infected or cancerous target cells. In recent years, this targeted killing capacity has emerged as a core component of several promising immunotherapeutic strategies to fight cancer. A better understanding of how cytotoxic T cells operate is therefore not only of biological interest but also of potential clinical relevance. T cells kill by first forming a close cell-cell interface, called an immunological synapse, with their targets. They then secrete a mixture of toxic proteins into the synapse, which damage the target's plasma membrane and intracellular contents. Recent biophysical studies have indicated that T cells exert a substantial amount of mechanical force across the synapse, which could potentially alter the shape and physical properties of the target cell. The experiments in this research will investigate the hypothesis that these forces boost killing by enhancing the activity of the toxic proteins secreted into the synapse. The idea that mechanical force and chemical signals cooperate in this manner is quite unappreciated and could represent an important new concept in the understanding of intercellular communication and immune function. The principal investigator will also develop a paid summer internship program in mechanobiology targeting female students at both the high school and university levels to provide them an entryway into a research career. The studies will focus on potential synergy between synaptic forces and the secreted cytolytic molecule perforin, which forms proteinaceous pores on the target cell membrane. Preliminary results suggest that synapse formation increases target cell membrane tension, thereby potentiating perforin pore formation. Biophysical methods will be merged with immunological assays in order to investigate this hypothesis. Polyacrylamide hydrogel substrates will be used to explore the relationship between target cell tension and perforin pore formation. Optical trap methodology will be used to quantify the effects of synapse formation on membrane tension. Finally, polydimethylsiloxine micropillar arrays will be used to examine the spatiotemporal coordination of force exertion and perforin secretion. The successful completion of these research goals could establish mechanopotentiation (i.e. the synergy between physical and chemical signals) as an important avenue for intercellular communication, which would broadly influence current conceptions and future studies of cell-cell interactions and mechanobiology.