Action and Signaling of Lysophosphatidylethanolamine in MDA-MB-231 Breast Cancer Cells

Previously, we reported that lysophosphatidylethanolamine (LPE), a lyso-type metabolite of phosphatidylethanolamine, can increase intracellular Ca²⁺ ([Ca²⁺]_i) via type 1 lysophosphatidic acid (LPA) receptor (LPA₁) and CD97, an adhesion G-protein-coupled receptor (GPCR), in MDA-MB-231 breast cancer cells. Furthermore, LPE signaling was suggested as like LPA₁/CD97-G_i/o proteins-phospholipase C-IP₃-Ca²⁺ increase in these cells. In the present study, we further investigated actions of LPE not only in the [Ca²⁺]_i increasing effect but also in cell proliferation and migration in MDA-MB-231 breast cancer cells. We utilized chemically different LPEs and a specific inhibitor of LPA₁, AM-095 in comparison with responses in SK-OV3 ovarian cancer cells. It was found that LPE-induced Ca²⁺ response in MDA-MB-231 cells was evoked in a different manner to that in SK-OV3 cells in terms of structural requirements. AM-095 inhibited LPE-induced Ca²⁺ response and cell proliferation in MDA-MB-231 cells, but not in SK-OV3 cells, supporting LPA₁ involvement only in MDA-MB-231 cells. LPA had significant effects on cell proliferation and migration in MDA-MB-231 cells, whereas LPE had less or no significant effect. However, LPE modulations of MAPKs (ERK1/2, JNK and p38 MAPK) was not different to those by LPA in the cells. These data support the involvement of LPA₁ in LPE-induced Ca²⁺ response and cell proliferation in breast MDA-MB-231 cells but unknown GPCRs (not LPA₁) in LPE-induced responses in SK-OV3 cells. Furthermore, although LPE and LPA utilized LPA₁, LPA utilized more signaling cascades than LPE, resulting in stronger responses by LPA in proliferation and migration than LPE in MDA-MB-231 cells.