Fluorescence-Based Measurements of Store-Operated Ca ²⁺ Entry in Cancer Cells Using Fluo-4 and Confocal Live-Cell Imaging

The store-operated calcium entry (SOCE) is the predominant calcium entry mechanism in cancer cell and other non-exciting cells. In the last few years, there is rapidly accumulating evidence supporting that SOCE is dysregulated in many types of cancer. The hyperactive SOCE in tumor cells is spatially and temporally coded to promote cell proliferation, migration, and invasion. In this chapter, we describe two protocols to measure SOCE in tumor cells. The first protocol employs fluorescent microplate readers and could be adapted for high-throughput screening. The second protocol takes advantage of laser scanning confocal microscopy and can be used to resolve the high-resolution spatial and temporal coding of SOCE signals in single cells. These protocols are useful tools to uncover the dysregulation of SOCE signaling in tumor malignancy.