Figure 7

Overview of the role of Orai1 in BCSC spheroid formation. MDA-MB-231-derived breast cancer stem cells (BCSC) overexpress Orai1 and exhibit a significant agonist-evoked Ca²⁺ mobilization, leading to an efficient spheroid (mammosphere) formation. BCSC derived from Orai1-deficient cells shows attenuated agonist-induced Ca²⁺ mobilization, as well as spheroid-forming capability, thus revealing the functional role of Orai1 in these cells. Expression of Orai1α or Orai1β in Orai1-deficient BCSC rescue both histamine-stimulated Ca²⁺ mobilization and the spheroid-forming ability with similar efficiency, which indicates that both Orai1 variants support BCSC function equally well.