Single-molecule manipulation and detection platform for studying cancer cell chemotaxis

Chemotaxis of cancer cells is an essential component of tumor dissemination. The chemotactic response is comprised of three separate steps, including chemosensing, polarization and locomotion. We present an innovative approach on chemotaxis assay to address cancer cell chemotaxis. We applied a high-resolution optical tweezers system to manipulate epidermal growth factor (EGF)-coated beads positioned close to the filopodia, to locally stimulate HT29 cells expressing the EGF receptor (EGFR). We demonstrated that membrane protrusion at the leading edge induced by an EGF chemotaxis occurred at about 30∼40 s. In addition, the present observation revealed that the locomotion of HT29 cell depended on whether the HT29 cell sensed the presence of the chemoattractant EGF. We anticipate the proposed approach based on optical tweezers, together with the platform at single-cell level, could be applied to build a quick screening method for detection and treatment evaluation of many types of cancer during chemotaxis.