Expression Of Sphingosine-1-phosphate Receptor 2 In Colorectal Cancer And Its Correlation With Cancer Invasion

AimSphingosine-1-phosphate(S1P)is a biologically active phospholipid that emerges as a regulator of cell growth,differentiation and apoptosis by binding to S1P receptors(S1PRs).There is substantial evidence that S1P signaling involved in the pathogenesis of a variety of diseases,including cancers.Recently studies showed that S1PR2 can inhibit growth and metastasis of tumor.However,little is known about the expression pattern of S1PRs and its effects on human colorectal cancer(CRC)metastasis.Here,we determined the role of S1PR2 in the metastasis of colorectal cancer and investigate the role of the S1P signaling in the metastasis of colon cancer cells and S1PRs expressed in CRC patient.Methods1.The level of SIP in patients and healthy individuals’ serum was quantified by enzyme-linked immunosorbent assay(ELISA).2.The expression of S1PRs and Sphingosine kinases(SphKs)mRNA levels in 55 colorectal patients was detected by quantitative real-time polymerase chain reaction(qRT-PCR).3.The expression of S1PR2 in 55 colorectal patients was detected on protein by western blot(WB)and Immunohistological analysis(IHC).4.The expression of S1PRs mRNA levels in two colon cancer cells with different malignancy was detected by quantitative real-time polymerase chain reaction(qRT-PCR).5.Methyl thiazolyl tetrazolium(MTT)assay and scratch assay were carried out for detecting the effect of exogenous addition of S1PR2 agonist S1P or S1PR2 antagonist JTE013 on the proliferation and migration of colon cancer cell.6.S1PR2-siRNA were used to determine the role of S1PR2 in the migration of colon cancer cell.Results1.The level of S1P in serum was significantly increased among CRC patients compare to healthy individuals(P<0.01).2.Relative mRNA expression level of S1PR2 was significantly down-regulated in tumor compare with normal tissue,whereas S1PR1 and SphK1 were up-regulated.3.WB results showed that in 58%(32/55 cases)patients presents a down-regulated S1PR2 expression in protein level.IHC results also indicated the expression level of S1PR2 was lower in 65.5%(36/55 cases)patients in tumor tissues compared with normal.4.SW480 with low malignancy that predominantly express S1PR2,LOVO with high malignancy that almost have no express of S1PR2.5.The exogenous addition of S1P,the natural ligand of the S1PRs has been shown to inhibited cancer cells proliferation and migration.Blockaged of S1PR2 by JTE013 significantly promoted the proliferation and migration of SW480.6.Inhibited the expression of S1PR2 by S1PR2-siRNA significantly promoted the migration of S W480.ConclusionsThe present study indicates that the expression levels of S1P receptors and Sphingosine kinases to be differences.The expression level of S1PR2 was significantly down-regulated in tumor compare with normal tissue,whereas S1PR1、4 and SphK1 were up-regulated.S1P can inhibit the proliferation and migration of colorectal cancer by S1PR2.