Simulating sharp gradients for short-term, Ca(2+) transients and long-term chemotaxis in cancer cells

Rapid progress in the elucidation of candidate genes and proteins that play a role in disease processes such as cancer has been possible with widespread use of genomics and proteomics in the last ten years. It is becoming important to adapt the knowledge gained from mass analytical techniques to visual techniques that enable spatial-temporal discernment of molecular events. This is significant, particularly for the study of pathways that regulate dynamic processes such as cell migration or early events associated with differentiation such as Ca(2+) signaling. This paper describes the use of techniques that create sharp growth factor gradients suitable for local activation of cell surface receptors. The methods involve retardation of the direct flow to create steep gradients at the surface plane where cells are grown. These methods are shown to be suitable for rapid biological assays such as Ca(2+) transients that occur within 1 min of receptor activation, demonstrating that the speed and level of Ca(2+) transients are related to gradient strength. A microfabricated chamber is also determined to be suitable for longer-term analyses such as cancer cell chemotaxis.