Anwesha Sarkar

SU-F-SPS-08: Measuring the Interaction Of DDR Cell Receptors and Extracellular Matrix Collagen in Prostate Cells

PURPOSE Discoidin domain receptors (DDR) have recently been recognized as important players in cancer progression. DDRs are cell receptors that interact with collagen, an extracellular matrix (ECM) protein. However the detailed mechanism of their interaction is unclear. Here we attempted to examine their interaction in terms of structural (surface topography), mechanical (rupture force), and kinetic (binding probability) information on the single molecular scale with the use of atomic force microscopy (AFM). METHODS The Quantitative Nano-mechanical property Mapping (QNM) mode of AFM allowed to assess the cells in liquid growth media at their optimal physiological while being viable. Human benign prostate hyperplasia (BPH-1) cell line was genetically regulated to suppress DDR expression (DDR- cells) and was compared with naturally DDR expressing cells (DDR+). RESULTS Binding force measurements (n = 1000) were obtained before and after the two groups were treated with fibronectin (FN), an integrin-inhibiting antibody to block the binding of integrin. The quantification indicates that cells containing DDR bind with collagen at a most probable force of 80.3-83.0 ±7.6 pN. The probability of them binding is 0.167 when other interactions (mainly due to integrin-collagen binding) are minimized. CONCLUSION Together with further force measurements at different pulling speeds will determine dissociation rate, binding distance and activation barrier. These parameters in benign cells provides some groundwork in understanding DDRs behavior in various cell microenvironments such as in malignant tumor cells. Funding supported by Richard Barber Interdisciplinary Research Program of Wayne State University.