Abstract
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive phospholipids that act as mitogens in various cancers. Both LPA and S1P activate G-protein coupled receptors (GPCRs). We examined the role of CCN1/CYR61, an inducible matricellular protein, in LPA-induced signal transduction in PC-3 human prostate cancer cells. We found that both LPA and S1P induced expression of CCN1 and CCN2 within 2-4 h. CCN1 was induced by 18:1-LPA, but not by 18:0-, 18:2-, or 18:3-LPAs. A free fatty acid receptor-4 agonist inhibited LPA-induced CCN1 induction. CCN1 appeared in the ECM within 2 h after LPA addition. LPA caused biphasic activation of Erk MAPK, with an initial peak at 10-20 min followed by a later phase after 6 h. LPA increased adhesion of PC-3 cells to culture substrates (standard culture plates, fibronectin, or extracellular matrix) at 2 h, an intermediate event between early and late LPA signals. Knockdown of CCN1 suppressed LPA-induced adhesion to ECM or fibronectin. ECM from CCN1 knockdown cells was a poor substrate for adhesion, as compared to ECM from control cells. These results suggest that CCN1 contributes to LPA responses in the tumor microenvironment. The LPA-CCN1 axis holds promise for the development of novel therapeutic strategies in cancer.