IP3R3 silencing induced actin cytoskeletal reorganization through ARHGAP18/RhoA/mDia1/FAK pathway in breast cancer cell lines.

Cell morphology is altered in the migration process, and the underlying cytoskeleton remodeling is highly dependent of intracellular Ca2+ concentration. Many calcium channels are known to be involved in migration. Inositol 1,4,5-trisphosphate receptor (IP3R) was demonstrated to be implicated in breast cancer cells migration, but its involvement in morphological changes during the migration process remains unclear. In the present work, we showed that IP3R3 expression was correlated to cell morphology. IP3R3 silencing induced rounding shape and decreased adhesion in invasive breast cancer cell lines. Moreover, IP3R3 silencing decreased ARHGAP18 expression, RhoA activity, Cdc42 expression and Y861FAK phosphorylation. Interestingly, IP3R3 was able to regulate profilin remodeling, without inducing any myosin II reorganization. IP3R3 silencing revealed an oscillatory calcium signature, with a predominant oscillating profile occurring in early wound repair. To summarize, we demonstrated that IP3R3 is able to modulate intracellular Ca2+ availability and to coordinate the remodeling of profilin cytoskeleton organization through the ARHGAP18/RhoA/mDia1/FAK pathway.

Angiogenesis Inhibition by a Short 13 Amino Acid Peptide Sequence of Tetrastatin, the α4(IV) NC1 Domain of Collagen IV.

Angiogenesis is defined as the formation of new capillaries by sprouting from the pre-existing microvasculature. It occurs in physiological and pathological processes particularly in tumor growth and metastasis. α1, α2, α3, and α6 NC1 domains from type IV collagen were reported to inhibit tumor angiogenesis. We previously demonstrated that the α4 NC1 domain from type IV collagen, named Tetrastatin, inhibited tumor growth in a mouse melanoma model. The inhibitory activity was located in a 13 amino acid sequence named QS-13. In the present paper, we demonstrate that QS-13 decreases VEGF-induced-angiogenesis in vivo using the Matrigel plug model. Fluorescence molecular tomography allows the measurement of a 65% decrease in Matrigel plug angiogenesis following QS-13 administration. The results are confirmed by CD31 microvessel density analysis on Matrigel plug slices. QS-13 peptide decreases Human Umbilical Vein Endothelial Cells (HUVEC) migration and pseudotube formation in vitro. Relevant QS-13 conformations were obtained from molecular dynamics simulations and docking. A putative interaction of QS-13 with α5ß1 integrin was investigated. The interaction was confirmed by affinity chromatography, solid phase assay, and surface plasmon resonance. QS-13 binding site on α5ß1 integrin is located in close vicinity to the RGD binding site, as demonstrated by competition assays. Collectively, our results suggest that QS-13 exhibits a mighty anti-angiogenic activity that could be used in cancer treatment and other pathologies with excessive angiogenesis such as hemangioma, psoriasis or diabetes.

Downregulation of type 3 inositol (1,4,5)-trisphosphate receptor decreases breast cancer cell migration through an oscillatory Ca2+ 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 (IP3Rs) remains enigmatic. If the three IP3Rs subtypes expression have been identified in various cancers, little is known about their physiological role. Here, we investigated the involvement of IP3R type 3 (IP3R3) 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 IP3R3 expression level, but not IP3R1 nor IP3R2, is correlated to a stronger cell line migration capacity and a sustained calcium signal. Interestingly, silencing of IP3R3 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 IP3R3 in MCF-7 cells significantly increases their migration capacities. This effect is completely reversed by IP3R3 silencing. In conclusion, we demonstrate that IP3R3 expression level increases the migration capacity of human breast cancer cells by changing the calcium signature.