sphingosine-1-phosphate and Stomach-Neoplasms

Sphingosine-1-phosphate, a pleiotropic bioactive lipid mediator, is an important player in cancer progression. Previous studies suggested that sphingosine-1-phosphate produced by sphingosine kinase 1, which is activated by phosphorylation, plays important roles in the progression of disease and metastasis. The association between phospho-sphingosine-1-phosphate produced by sphingosine kinase 1 and clinical parameters in human gastric cancer have not been fully investigated to date.. We created phospho-sphingosine-1-phosphate produced by sphingosine kinase expression profiles by immunohistochemistry for 136 patients who underwent operative intervention for gastric cancer in 2007-2009. Phospho-sphingosine-1-phosphate produced by sphingosine kinase expression and compared clinicopathologic factors by univariate and multivariate analyses.. The univariate analysis revealed that phospho-sphingosine-1-phosphate produced by sphingosine kinase expression was correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, histologic type, and lymphatic invasion. The multivariate analysis revealed that the diffuse type (odds ratio 2.210; 95% confidence interval, 1.045-4.671, P=.038) and the presence of lymphatic invasion (odds ratio 3.697; 95% confidence interval, 1.161-8.483, P=.002) were associated independently with phospho-sphingosine-1-phosphate produced by sphingosine kinase expression in patients with gastric cancer. The 5-year rate of disease-specific survival was 79.3% in patients with phospho-sphingosine-1-phosphate produced by sphingosine kinasephospho-sphingosine-1-phosphate produced by sphingosine kinase-positive expression and 98.3% in those with phospho-sphingosine-1-phosphate produced by sphingosine kinase-negative expression (P=.002). In multivariate analysis, however, high phospho-sphingosine-1-phosphate produced by sphingosine kinase expression was not an independent prognostic factor for disease-specific survival (hazard ratio 5.540; 95% confidence interval, 0.717-42.81, P=.100).. We provide the first evidence that diffuse histologic type and lymphatic invasion were independently associated with high phospho-sphingosine-1-phosphate produced by sphingosine kinase expression in gastric cancer patients, indicating a role of sphingosine-1-phosphate in disease progression among patients with gastric cancer. (Surgery 2017;160:XXX-XXX.).

Topics: Adult; Aged; Aged, 80 and over; Female; Gastrectomy; Humans; Japan; Lymph Node Excision; Lymphatic Metastasis; Lysophospholipids; Male; Middle Aged; Neoplasm Invasiveness; Neoplasm Staging; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Retrospective Studies; Sphingosine; Stomach Neoplasms; Survival Rate

Sphingosine-1-phosphate (S1P) plays an important role in regulating many biological processes. Sphingosine-1-phosphate phosphatase 1 (SGPP1) can dephosphorylate S1P into sphingosine and tip the balance of sphingosine-S1P. Increased levels of sphingosine leads to a decrease in the ability of cell invasion as well as an increase in the ability of cell apoptosis. However, little is known regarding the effects of SGPP1 in gastric cancer. The present study examined the function of SGPP1 on gastric cancer cell lines as well as its clinical relevance in gastric cancer progression. Using immunohistochemistry and RT-qPCR techniques, the clinical significance of SGPP1 expression was analyzed in 288 paraffin-embedded gastric tissue specimens and 219 fresh gastric tissues, respectively. Transgenes encoding ribozymes to specifically target human SGPP1 (pEF-SGPP1) was constructed. Human gastric cancer cell lines (AGS and HGC27) were transfected with pEF-SGPP1 transgene and examined by functional analysis. SGPP1 was downregulated in gastric cancer tissues, compared with adjacent normal gastric tissues (p=0.034). SGPP1 mRNA levels in gastric cancer tissues were significantly decreased when compared with their adjacent non-cancerous tissues (p<0.001). Weakly expressed SGPP1 was positively correlated with the lymph node metastasis (p=0.005) and distant metastasis (p=0.031). Kaplan-Meier survival curves revealed that patients with SGPP1 positive expression had a significant increase in overall survival (OS) (p=0.034) and progression-free survival (PFS) (p=0.041). Multivariate analysis indicated the expression of SGPP1 was an independent prognostic factor in gastric cancer patients (p=0.041). In vitro experiments showed that knockdown of SGPP1 resulted in an increase in the invasion (2-fold) and migration (5-fold) of AGS and HGC27. The two gastric cancer cells transfected with pEF-SGPP1 exhibited a slower rate of growth with less adhesion. Thus, our findings provided evidence that SGPP1 may serve as a prognostic biomarker for patients with advanced gastric cancers.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Cell Line, Tumor; Cell Movement; Disease-Free Survival; Female; Gene Expression Regulation, Neoplastic; Humans; Kaplan-Meier Estimate; Lysophospholipids; Male; Membrane Proteins; Middle Aged; Phosphoric Monoester Hydrolases; Prognosis; RNA, Messenger; Sphingosine; Stomach Neoplasms; Transfection

Resistance to chemotherapy is common in gastroesophageal cancer. Mechanisms of resistance are incompletely characterised and there are no predictive biomarkers in clinical practice for cytotoxic drugs. We used new cell line models to characterise novel chemotherapy resistance mechanisms and validated them in tumour specimens to identify new targets and biomarkers for gastroesophageal cancer.. Cell lines were selected for resistance to oxaliplatin, cisplatin and docetaxel and gene expression examined using Affymetrix Exon 1.0 ST arrays. Leads were validated by qRT-PCR and HPLC of tumour metabolites. Protein expression and pharmacological inhibition of lead target SPHK1 was evaluated in independent cell lines, and by immunohistochemistry in gastroesophageal cancer patients.. Genes with differential expression in drug resistant cell lines compared to the parental cell line they were derived from, were identified for each drug resistant cell line. Biological pathway analysis of these gene lists, identified over-represented pathways, and only 3 pathways - lysosome, sphingolipid metabolism and p53 signalling- were identified as over-represented in these lists for all three cytotoxic drugs investigated. The majority of genes differentially expressed in chemoresistant cell lines from these pathways, were involved in metabolism of glycosphingolipids and sphingolipids in lysosomal compartments suggesting that sphingolipids might be important mediators of cytotoxic drug resistance in gastroeosphageal cancers . On further investigation, we found that drug resistance (IC50) was correlated with increased sphingosine kinase 1(SPHK1) mRNA and also with decreased sphingosine-1-phosphate lysase 1(SGPL1) mRNA. SPHK1 and SGPL1 gene expression were inversely correlated. SPHK1:SGPL1 ratio correlated with increased cellular sphingosine-1-phosphate (S1P), and S1P correlated with drug resistance (IC50). High SPHK1 protein correlated with resistance to cisplatin (IC50) in an independent gastric cancer cell line panel and with survival of patients treated with chemotherapy prior to surgery but not in patients treated with surgery alone. Safingol a SPHK1 inhibitor, was cytotoxic as a single agent and acted synergistically with cisplatin in gastric cancer cell lines.. Agents that inhibit SPHK1 or S1P could overcome cytotoxic drug resistance in gastroesophageal cancer. There are several agents in early phase human trials including Safingol that could be combined with chemotherapy or used in patients progressing after chemotherapy.

Topics: Aldehyde-Lyases; Antineoplastic Agents; Cell Line, Tumor; Drug Resistance, Neoplasm; Esophageal Neoplasms; Female; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Lysophospholipids; Male; Phosphotransferases (Alcohol Group Acceptor); Real-Time Polymerase Chain Reaction; RNA, Neoplasm; Signal Transduction; Sphingosine; Stomach Neoplasms

We previously reported that sphingosine kinase 1 (SphK1), an enzyme that catalyzes the production of sphingosine-1-phosphate (SIP), is upregulated in human gastric cancer and predicts poor clinical outcome. In the present study, we used known differential effects of UV irradiation on human MGC-803 gastric cancer cells to determine their effect on SphK1 activity. Ectopic expression of SphK1 in MGC-803 gastric cancer cells markedly enhanced their resistance to UV irradiation, whereas silencing endogenous SphK1 with shRNAs weakened this ability. Furthermore, these anti-apoptotic effects were significantly associated with decrease of Bim, an apoptosis-related protein. We further demonstrated that SphK1 could downregulate the transcriptional activity of forkhead box O3a (FoxO3a) by inducing its phosphorylation, which was found to be associated with the PI3K/Akt signaling. Taken together, our study supports the theory that SphK1 confers resistance to apoptosis in gastric cancer cells via the Akt/FoxO3a/Bim pathway.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Carcinoma; Cell Line, Tumor; Down-Regulation; Forkhead Box Protein O3; Forkhead Transcription Factors; Gene Expression Regulation, Neoplastic; Gene Silencing; Humans; Lysophospholipids; Membrane Proteins; Phosphatidylinositol 3-Kinases; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering; Signal Transduction; Sphingosine; Stomach Neoplasms; Ultraviolet Rays; Up-Regulation

Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are lysophospholipid mediators of diverse cellular processes important for cancer progression. S1P is produced by two sphingosine kinases, SphK1 and SphK2. Expression of SphK1 is elevated in many cancers. Here, we report that LPA markedly enhanced SphK1 mRNA and protein in gastric cancer MKN1 cells but had no effect on SphK2. LPA also up-regulated SphK1 expression in other human cancer cells that endogenously express the LPA(1) receptor, such as DLD1 colon cancer cells and MDA-MB-231 breast cancer cells, but not in HT29 colon cancer cells or MDA-MB-453 breast cancer cells, which do not express the LPA(1) receptor. An LPA(1) receptor antagonist or down-regulation of its expression prevented SphK1 and S1P(3) receptor up-regulation by LPA. LPA transactivated the epidermal growth factor receptor (EGFR) in these cells, and the EGFR inhibitor AG1478 attenuated the increased SphK1 and S1P(3) expression induced by LPA. Moreover, down-regulation of SphK1 attenuated LPA-stimulated migration and invasion of MNK1 cells yet had no effect on expression of neovascularizing factors, such as interleukin (IL)-8, IL-6, urokinase-type plasminogen activator (uPA), or uPA receptor induced by LPA. Finally, down-regulation of S1P(3), but not S1P(1), also reduced LPA-stimulated migration and invasion of MKN1 cells. Collectively, our results suggest that SphK1 is a convergence point of multiple cell surface receptors for three different ligands, LPA, EGF, and S1P, which have all been implicated in regulation of motility and invasiveness of cancer cells.

Topics: Blotting, Western; Breast Neoplasms; Cell Movement; Cell Proliferation; Chemotaxis; Colonic Neoplasms; ErbB Receptors; Humans; Interleukin-6; Interleukin-8; Lysophospholipids; Neoplasm Invasiveness; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysophosphatidic Acid; Receptors, Lysosphingolipid; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sphingosine; Stomach Neoplasms; Transcriptional Activation; Tumor Cells, Cultured; Up-Regulation; Urokinase-Type Plasminogen Activator

Sphingosine 1-phosphate (S1P) is a bioactive lysophospholipid, derived from activated platelet, that is known to induce diverse cellular responses through at least five G-protein-coupled receptors on various cell types. Abnormal platelet and coagulation activation is often seen in patients with gastric cancer. However, neither the effects of this platelet-derived mediator S1P nor the distribution of S1P receptors on the gastric cancer cell are fully understood. The aim of this study was to examine the possible role of S1P and its receptors in the progression of gastric cancer.. We characterized the expression profiles of S1P receptors in nine human gastric cancer cell lines and evaluated the relationship between the responses to S1P and its receptor expression on cell migration by modified Boyden chamber and cell proliferation by MTS assay.. Northern blotting analysis has revealed that S1P2 was expressed in all gastric cancer cell lines to varying degrees, and S1P3 was expressed in four cell lines. S1P1 expression was weak, and no significant expression of either S1P4 or S1P5 was detected. The addition of S1P markedly stimulated the migration of MKN1 and HCG-27 that dominantly expressed S1P3, and the effect was potently inhibited by pertussis toxin or wortmannin. In contrast, SIP significantly inhibited the migration of AZ-521 that expressed S1P2 exclusively. This indicates that the balance between S1P2- and S1P3-mediated signals might be critical in determining the metastatic response of gastric cancer cells to S1P. S1P elicited weak but significant antiproliferative effects on all of the three cell lines, although the effects were not major. In these cells, S1P induced extracellular signal-regulated kinase (ERK) phosphorylation with transient Akt dephosphorylation that may cause the weak effects on proliferation.. Our results suggest that the S1P receptor expression may critically determine the biological behavior of gastric cancers and thus therapeutic interventions directed at each S1P receptor might be clinically effective in preventing metastasis in gastric cancer.

Topics: Cell Division; Cell Line, Tumor; Cell Movement; Down-Regulation; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; Lysophospholipids; Pertussis Toxin; Phosphatidylinositol 3-Kinases; Phosphorylation; Proto-Oncogene Proteins c-akt; Receptors, Lysosphingolipid; Sphingosine; Stomach Neoplasms

The ligand-less receptor HER2/neu (erbB-2) has been proposed as a prognostic marker of gastric cancer that correlates with poor clinical outcome, indicating that HER2 signals play an important role in gastric cancer progression. This study demonstrated that two major natural lysophospholipids, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), induce rapid and transient phosphorylation of HER2 in two human gastric cancer cell lines, MKN28 and MKN74 cells. We also revealed that tyrosine phosphorylation of HER2 induced by both lysophospholipids was significantly attenuated by two inhibitors, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, AG1478, and a broad-spectrum matrix metalloproteinase inhibitor, GM6001. This suggests that the pathway of HER2 transactivation induced by these lysophospholipids is dependent on the proteolytically released EGFR ligands. Our results indicate that LPA and S1P act upstream of HER2 in gastric cancer cells, and thus may act as potent stimulators of gastric cancer.

Topics: Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors; ErbB Receptors; Genes, erbB-2; Humans; Lysophospholipids; Metalloendopeptidases; Phosphorylation; Protein-Tyrosine Kinases; Receptor, ErbB-2; Sphingosine; Stomach Neoplasms; Transcriptional Activation; Tumor Cells, Cultured

Receptor tyrosine kinases (RTKs) are transactivated by the stimulation of G protein-coupled receptors (GPCRs). Sphingosine 1-phosphate (S1P), a ligand of GPCR, is known as a tumor-promoting lipid, but its signaling pathways are not fully understood. We here demonstrated that S1P induces rapid and transient tyrosine phosphorylation of epidermal growth factor receptor (EGFR) and c-Met in gastric cancer cells, both of which have been proposed as prognostic markers of gastric cancers. The pathway of S1P-induced c-Met transactivation is Gi-independent and matrix metalloproteinase-independent, which differs from that of EGFR transactivation. Our results indicate that S1P acts upstream of various RTKs and thus may act as a potent stimulator of gastric cancer.

Topics: Blotting, Western; Cell Line, Tumor; ErbB Receptors; Humans; Lysophospholipids; Models, Biological; Phosphorylation; Precipitin Tests; Proto-Oncogene Proteins c-met; Sphingosine; Stomach Neoplasms; Transcriptional Activation; Tyrosine