Downregulation of type 3 inositol (1,4,5)-trisphosphate receptor decreases breast cancer cell migration through an oscillatory Ca 2+ signal.

Breast cancer remains a research priority due to its invasive phenotype. Although the role of ion channels in cancer is now well established, the role of inositol (1,4,5)-trisphosphate (IP3 ) receptors (IP3 Rs) remains enigmatic. If the three IP3 Rs subtypes expression have been identified in various cancers, little is known about their physiological role. Here, we investigated the involvement of IP3 R type 3 (IP3 R3 ) in the migration processes of three human breast cancer cell lines showing different migration velocities: the low-migrating MCF-7 and the highly migrating and invasive MDA-MB-231 and MDA-MB-435S cell lines. We show that a higher IP3 R3 expression level, but not IP3 R1 nor IP3 R2, is correlated to a stronger cell line migration capacity and a sustained calcium signal. Interestingly, silencing of IP3 R3 highlights an oscillating calcium signaling profile and leads to a significant decrease of cell migration capacities of the three breast cancer cell lines. Conversely, stable overexpression of IP3 R3 in MCF-7 cells significantly increases their migration capacities. This effect is completely reversed by IP3 R3 silencing. In conclusion, we demonstrate that IP3 R3 expression level increases the migration capacity of human breast cancer cells by changing the calcium signature.