10] Probing redox activity of human breast cells by scanning electrochemical microscopy

Abstract

As a specific application of scanning electrochemical microscope (SECM), intrinsic redox reactivity is compared to topographies of metastatic and nonmetastatic human breast cell lines. One of the many properties that distinguish these cell lines is the expression level of protein kinase Cα (PKCα), a redox-sensitive enzyme that has been linked with motility and metastasis of various cell types. MCF-10A cells are nontransformed, nonmetastatic cells that express very low levels of PKCα. When MCF- 10A cells are genetically engineered to overproduce PKCα, these normally nonmotile cells exhibit a high degree of motility (renamed as 11α cells). The SECM is used to measure and compare the redox reactivity of MCF-10A cells, 11α cells, and overtly metastatic MDA-MB-231 human breast cells (which also express high levels of PKCα). With respect to the kinetics of transmembrane charge transfer by a variety of redox mediators, nonmotile and motile cells exhibit distinct and reproducible differences. The measurements of redox reactivity may help define a property of human breast cells that distinguishes nonmetastatic and metastatic cells. In addition to redox reactivity, other chemical processes occurring in living cells (for example, diffusion of oxygen or pumping of H + across the membrane) can be detected with potentiometric or amperometric electrodes and imaged with submicrometer spatial resolution.