Signal Pathway Study Of Inhibitory Effects Of S1P On Migration Of Cancer Cells Via S1PR2

Cancer is one of the major diseases endangering health and known to be regulated by a lot of signaling pathways. There are five SIP receptors on cell membrane, including S1PR1, S1PR2, S1PR3, S1PR4 and S1PR5.They can be activated by SIP, mediate cell signaling pathways and regulate cell physiological functions such as cell proliferation, migration, apoptosis and angiogenesis etc. These receptors, which are transmembrane proteins, can couple with different types of G protein to activate downstream signaling molecules. Cancer metastasis is one of the important causes leading to the deterioration and recurrence of cancer. It has been reported that the migration of endothelial cells could be inhibited by S1PR2 as well as the migration of smooth muscle cells which results in suppression of atherosclerosis. We suspect that the effect of S1PR2 on migration of tumor cells may have a great influence on tumor metastasis. Thus, it is important to explore the role of S1PR2 in tumor cell migration and its signaling pathway for tumor treatment research. In this study, Real Time PCR was performed to detect S1PRs expression in a variety of cells. Human gastric cancer cells, including SGC-7901 and BGC-803, which endogenous S1PR2 expression level is high, were stimulated by SIP to detect their cell migrations with Micro Chemotaxis Chamber. JTE-013, an antagonist of S1PR2, was used to pretreat cells and then migrations of these cells stimulated by SIP were detected to explore the role of S1PR2 in tumor cell migration. The entire coding region of S1PR2 was cloned and ligated into the mammalian expression vector pIRES-EGFP. To construct the cell model, S1PR2 overexpression vector was transfected into A549 cells in which S1PR2 endogenous expression is low. In order to further confirm the role of S1PR2 in tumor cell migration, A549 cells transfected with S1PR2 overexpression vector were stimulated by S1P to detect cell migrations. The signaling pathways of S1PR2 inhibiting cell migration were explored in SGC-7901 cells, in which endogenous expression is high, by pretreating cells with different kinds of signaling molecular inhibitors including:PTX, an inhibitor of Gi; PD98059, an inhibitor of ERK; Y27632, an inhibitor of Rho kinase; BAY, an inhibitor of NF-κB. The results showed that S1PR3 was highly expressed in A549 cells, HCT-116 cells, HO-8910 cells and A2780 cells, and had a higher expression than S1PR2. However S1PR2 expression in gastric cancer cells that we detected was high. When stimulated by SIP, cell migration was inhibited, and this inhibition could be eliminated by JTE-013, suggesting S1PR2 inhibits migration of SGC-7901 cells via SIP. The ability of cell migration inhibited by SIP/S1PR2 was restored when cells were pretreated with the inhibitors PTX, PD98059, Y27632 or BAY, suggesting Gi protein, ERK, Rho kinase (ROCK) and NF-κB were involved in the inhibition of cell migration caused by S1P/S1PR2. Our study demonstrates that S1PR2 plays a role in the inhibition of cancer cell migration, and it may be a potential molecular target in future treatment for cancer.