Real-time monitoring of estrogen-regulated gene expression in single, living breast cancer cells: a new paradigm for the study of molecular dynamics.

Elucidation of the molecular mechanisms underlying the development and progression of breast cancer has been hindered by two considerations. First, mammary tumor cells exhibit a considerable degree of morphological and functional heterogeneity. Thus, the conventional strategy of measuring a population response may not provide an accurate reflection of the behavior of the functional unit: an individual cell. Second, important regulatory events are generally separated in time, yet the strategies we use to monitor them are usually static as opposed to dynamic. With these considerations in mind, it would appear that a system for studying this problem should ideally combine the resolving power of single-cell analysis with a dynamic paradigm for making multiple measurements of gene expression from the same, living cell. This report summarizes our efforts at developing, validating, and optimizing such a system for monitoring hormone-driven gene expression in T47-D human breast cancer cells.