Epac increases melanoma cell migration by a heparan sulfate-related mechanism

Abstract

2009.-Melanoma, the most malignant form of human skin cancer, has a poor prognosis due to its strong metastatic ability. It was recently demonstrated that Epac, an effector molecule of cAMP, is involved in regulating cell migration; however, the role of Epac in melanoma cell migration remains unclear. We thus examined whether Epac regulates cell migration and metastasis of melanoma. Epac activation, by either specific agonist or overexpression of Epac, increased melanoma cell migration. Deletion of endogenous Epac with small interfering RNA decreased basal melanoma cell migration. These data suggested a major role of Epac in melanoma cell migration. Epac-induced cell migration was mediated by translocation of syndecan-2, a cell-surface heparan sulfate proteoglycan, to lipid rafts. This syndecan-2 translocation was regulated by tubulin polymerization via the Epac/phosphoinositol-3 kinase pathway. Epacinduced cell migration was also regulated by the production of heparan sulfate, a major extracellular matrix. Epac-induced heparan sulfate production was attributable to the increased expression of N-deacetylase/N-sulfotransferase-1 (NDST-1) accompanied by an increased NDST-1 translation rate. Finally, Epac overexpression enhanced lung colonization of melanoma cells in mice. Taken together, these data indicate that Epac regulates melanoma cell migration/ metastasis mostly via syndecan-2 translocation and heparan sulfate production. metastasis; phosphoinositol-3 kinase; N-deacetylase/N-sulfotransferase-1

Exchange Protein Directly Activated by Cyclic AMP Increases Melanoma Cell Migration by a Ca2+-Dependent Mechanism

“…These results suggest that Ca 2+ -dependent cell migration occurs first, followed by heparan sulfate-related cell migration. Regarding the status of Epac activation, our data suggest that the heparan sulfate-related mechanism is involved in both basal and Epac-activated conditions (9), but the Ca 2+ -dependent mechanism participates only in an Epac-activated condition. Melanoma cell migration was reduced under both basal and Epac-activated conditions with inhibition of molecules involved in the heparan sulfate-related mechanism (9).…”

“…Because Epac1 expression was higher in SK-Mel-187 than in SK-Mel-2, these data suggest that Epac1 expression positively correlates, at least in part, with Rap1 activation, and the resultant Ca 2+ elevation in melanoma. We previously reported that heparan sulfate is involved in Epac-induced melanoma cell migration (9). Using SK-Mel-2 cells, we showed that Epac mediates cell migration via increased heparan sulfate production.…”

“…5B). Again, ablation of PLCε and IP 3 R1 did not reduce basal migration whereas ablation of Epac1 did, suggesting the involvement of another mechanism in Epac1-induced cell migration, i.e., the heparan sulfaterelated mechanism (9). Taken together, these data suggested that Epac increases melanoma cell migration via the PLCε/ IP 3 R/Ca 2+ signaling pathway, and it occurs only under Epacactivated conditions.…”

“…Immunocytochemistry was performed as we previously described (9). Cells grown on glass coverslips were fixed, permeabilized, and incubated sequentially with primary antibodies for MHCIIA or S100A4 and respective secondary antibodies.…”

“…In cancer cells, reports show that Epac mediates cell adhesion in Ovcar3 cells (5), apoptosis (6), and growth arrest (7) in B lymphoma cells, formation of embryonic vasculogenic networks in melanoma cells (8), and proliferation of prostate carcinoma cells (7). We have previously reported that Epac increases melanoma cell migration by a heparan sulfate-related mechanism (9). Additionally, we found that Epac could also increase melanoma cell migration without significantly increasing heparan sulfate production, suggesting the existence of a heparan sulfate-independent mechanism in Epac-induced melanoma cell migration.…”