Traction Cytometry Assay: A Method to Quantify Traction Force Exerted by Cancer Cells on ECM

- Cells generate mechanical forces that act on an extracellular matrix. This force is called traction force. Cells exert traction forces to perform various tasks such as migration and proliferation.

Metastatic cancer cells exert greater traction forces than healthy cells; therefore, we perform a traction cytometry assay to measure the traction forces exerted by cells on elastic substrates. Begin by seeding the desired amount of colon cancer cells on a polyacrylamide hydrogel, a gel that mimics ECM in vitro. The gel comprises fibronectin proteins, which help cells to adhere to the surface, and fluorescent beads, which act as a marker for positional changes.

Incubate the cells for the desired period. The cells adhere to the gel and exert the traction force, which causes displacement of the fluorescent beads. Now, place the plate under a fluorescent microscope and take an image of the displaced fluorescent beads. Next, add the desired amount of trypsin to the plate to detach the cells and analyze the traction force exerted by the cells using appropriate software. In the following protocol, we will perform a traction force microscopy assay to analyze cellular traction of human colon ca