sphingosine-kinase and Stomach-Neoplasms

Gastric cancer peritoneal dissemination (GCPD) has been recognized as the most common form of metastasis in advanced gastric cancer (GC), and the survival is pessimistic. The injury of mesothelial cells plays an important role in GCPD. However, its molecular mechanism is not entirely clear. Here, we focused on the sphingosine kinase 1 (SPHK1) in human peritoneal mesothelial cells (HPMCs) which regulates HPMCs autophagy in GCPD progression. Initially, we analyzed SPHK1 expression immunohistochemically in 120 GC peritoneal tissues, and found high SPHK1 expression to be significantly associated with LC3B expression and peritoneal recurrence, leading to poor prognosis. Using a coculture system, we observed that GC cells promoted HPMCs autophagy and this process was inhibited by blocking TGF-β1 secreted from GC cells. Autophagic HPMCs induced adhesion and invasion of GC cells. We also confirmed that knockdown of SPHK1 expression in HPMCs inhibited TGF-β1-induced autophagy. In addition, SPHK1-driven autophagy of HPMCs accelerated GC cells occurrence of GCPD in vitro and in vivo. Moreover, we explored the relationship between autophagy and fibrosis in HPMCs, observing that overexpression of SPHK1 induced HPMCs fibrosis, while the inhibition of autophagy weakened HPMCs fibrosis. Taken together, our results provided new insights for understanding the mechanisms of GCPD and established SPHK1 as a novel target for GCPD.

Topics: Aged; Aged, 80 and over; Animals; Autophagy; Biomarkers; Cell Adhesion; Cell Line, Tumor; Disease Models, Animal; Female; Gene Expression Regulation; Humans; Immunohistochemistry; Male; Mice; Microtubule-Associated Proteins; Middle Aged; Models, Biological; Peritoneal Neoplasms; Phosphotransferases (Alcohol Group Acceptor); Prognosis; Stomach Neoplasms; Xenograft Model Antitumor Assays

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

We intended to clarify the role of sphingosine kinase 1 (SPHK1) in gastric cancer (GC) using both in vitro and in vivo assays. The study was designed to identify novel therapeutic targets for GC treatment. Differential analysis was utilized to dissect two gene expression omnibus series (GSE49515 and GSE79973) microarray data form Gene Expression Omnibus (GEO) (https://www.ncbi.nlm.nih.gov/geo/) dataset. MRNA and protein expressions were determined by quantitative polymerase chain reaction and Western blot, respectively. GC cell growth was measured by MTT assays and verified by in vivo analysis. Cell cycle and cell apoptosis were detected via flow cytometer observation. Cell migration and invasion were assessed by wound healing assays and Transwell assays. The targeting relationship between miRNA and SPHK1/S1PR1 was identified via dual-luciferase assay. Twenty-four common differentially expressed genes were screened out from two gene expression omnibus series (GSE49515 and GSE79973), among which SPHK1 was chosen for its higher fold change. We found elevated SPHK1 expression in GC tissues and cells, along with an increased concentration of SPHK1-generated sphingosine-1-phosphate (S1P) in both GC serum and tissue. SPHK1 knockdown significantly suppressed cell proliferation, migration, and invasion of MKN1 and KATO3 cells. It also blocked cell cycle and induced apoptosis in MKN1 and KATO3 cells. Silencing of SPHK1 also refrained tumor growth and inhibited S1P level. MiR-330-3p directly targeted SPHK1 and S1PR1. Overexpressed miR-330-3p in MKN1 cells repressed SPHK1 and S1PR1 expressions like their chemical inhibitors-SPHK1 inhibitors (FTY720) and S1PR1 inhibitors (VPC23019), and acted anti-tumor both in vitro and in vivo. Our study provides evidence that SPHK1 was promotive for GC tumor growth and cell biological behaviors, and that miR-330-3p targeted 3'-UTR of SPHK1 and inhibited its expression. SPHK1 was expected to become a new molecular marker and miR-330-3p a novel therapeutic target for GC. © 2018 IUBMB Life, 70(11):1164-1176, 2018.

Topics: Animals; Apoptosis; Carcinogens; Cell Cycle; Cell Movement; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; MicroRNAs; Phosphotransferases (Alcohol Group Acceptor); Prognosis; Stomach Neoplasms; Tumor Cells, Cultured; Up-Regulation; Xenograft Model Antitumor Assays

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

SKI-II has been reported as an inhibitor of sphingosine kinase 1 and has been extensively used to prove the involvement of sphingosine kinase and sphingosine-1-phosphate (Sphk1) in cellular processes. In the current study, we investigated the effects of SKI-II and its potential mechanisms in human gastric cancer SGC7901 cells. After treatment with SKI-II, cell growth, cell cycle distribution, apoptosis, expression of Sphk1, NF-κB, Bcl-2, Bax and p27 were assessed by MTT assay, flow cytometry, electron microscopy, immunocytochemistry and Western-blot assay, respectively. Our results showed that SKI-II markedly inhibited SGC7901 cell survival in a dose-dependent manner, reduced cell proliferation with accumulation of cells in the G0/G1 phase and induced apoptosis in the tumor cells. Furthermore, Western blotting and immunocytochemistry showed that the expression of p27 and Bax was increased significantly, but the expression of NF-κB, Bcl-2 and Sphk1 decreased by different degrees. These results indicate that SKI-II induced cell growth arrest and apoptosis. The increased apoptotic sensitivity of SGC7901 was correlated with NF-κB or Bcl-2/Bax activation.

Topics: Apoptosis; bcl-2-Associated X Protein; Cell Line, Tumor; Cell Proliferation; Cell Survival; Humans; NF-kappa B; Phosphotransferases (Alcohol Group Acceptor); Proliferating Cell Nuclear Antigen; Proto-Oncogene Proteins c-bcl-2; Stomach Neoplasms; Thiazoles

To explore the molecular mechanism of miR-124 suppressing the proliferation and invasion of gastric cancer cells.. SPHK1 3'UTR-luciferase vector was constructed and luciferase reporter gene assay was employed to examine the effect of miR-124 on luciferase activity. Human gastric cancer MGC-803 cells were transfected with miR-124 mimics, and then Western blot was performed to detect the expression of SPHK1 protein.. Luciferase reporter vector system confirmed that SPHK1 was a target gene of miR-124. Western blot showed that the expression of SPHK1 protein was inhibited by miR-124. After transfection of miR-124 mimics or SPHK1 siRNA for 12 h, 24 h and 48 h, respectively, MTT assay showed that the A values of the three groups were significantly different (P < 0.05), and it was in a time-dependent manner. After transfection of miR-124 mimics or SPHK1 siRNA for 24 h, transwell invasion assay showed that the number of transmembrane cells was 54.6 ± 8.3 in the SPHK1 siRNA group and 47.8 ± 6.6 in the miR-124 mimics group, both were significantly lower than 100.6 ± 11.3 of the control group (P < 0.05), indicating that SPHK1 siRNA can slow down the invasion of MGC-803 cells.. miR-124 can suppress the cell proliferation and invasion by targeting SPHK1 in gastric carcinoma.

Topics: Cell Line, Tumor; Cell Proliferation; Genetic Vectors; Humans; Luciferases; MicroRNAs; Neoplasm Invasiveness; Phosphotransferases (Alcohol Group Acceptor); Recombinant Proteins; RNA, Small Interfering; Stomach Neoplasms; Transfection

SPHK1 expression is elevated in gastric cancer and is associated with shorter survival times for patients. However, the molecular mechanism of SPHK1 up-regulation in gastric cancer remains unclear. In the present study, we report that miR-124 down-regulated SPHK1 expression by directly targeting its 3'-untranslated region (3'-UTR) and that miR-124 expression was inversely correlated with SPHK1 expression in gastric cancer samples. Furthermore, we demonstrated that, similar to the effect of silencing SPHK1, up-regulation of miR-124 markedly inhibited proliferation and tumourigenicity of gastric cancer cells both in vitro and in vivo. This was found to be mechanistically associated with induction of cyclin-dependent kinase inhibitors p21$^{{\\rm Cip1}}$ and p27$^{{\\rm Kip1}}$, enhancement of the transcriptional activity of FOXO1 and suppression of AKT activity. Moreover, we showed that the re-introduction of SPHK1 (without the 3'-UTR), but not with the 3'-UTR, could abrogate the miR-124-mediated induction of p21$^{{\\rm Cip1}}$ and p27$^{{\\rm Kip1}}$, as well as rescue the miR-124-induced proliferation inhibition. Together, these results suggest that miR-124 has an important role in the suppression of gastric cancer and presents a novel mechanism of miRNA-mediated SPHK1 expression in cancer cells.

Topics: Adenocarcinoma; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Down-Regulation; Forkhead Box Protein O1; Forkhead Transcription Factors; Humans; In Vitro Techniques; MicroRNAs; Phosphotransferases (Alcohol Group Acceptor); Proto-Oncogene Proteins c-akt; Signal Transduction; Stomach Neoplasms

To study the effect of the sphingosine kinase 1 (SphK1) inhibitor N,N-dimethylsphingosine (DMS) in combination with chemotherapeutic drugs (DDP, 5-Fu, MMC) on the proliferation of gastric cancer cells (SGC7901) in vitro, and to evaluate whether SphK1 inhibitors could be used as synergetic agents in chemotherapy.. SGC7901 cells were incubated in vitro with DMS (1 micromol/L) and 5-Fu, DDP, MMC at different concentrations in combination or separately for 24 h. The effects on the growth and survival of SGC7901 cells were determined by MTT assay. The inhibition rates were assessed by response surface analysis and the interactive relationships between the combined drugs were evaluated on the basis of positive/negative values of the cross product coefficients in the response surface equation.. The growth inhibition rate of the gastric cancer cells by treatment with DMS (1 micromol/L) was (10.23 +/- 0.74)%. The growth inhibition rates of the gastric cancer cells treated with 5-Fu (1, 5 and 25 microg/ml) for 24 h were (9.95 +/- 3.24)%, (21.04 +/- 2.19)%, and (45.49 +/- 3.60)%, respectively. The growth inhibition rates of the gastric cancer cells treated with DDP (0.5, 2.5 and 12.5 microg/ml) for 24 h were (9.38 +/- 0.79)%, (19.61 +/- 0.90)%, and (29.83 +/- 0.54)%, respectively. The growth inhibition rates of the gastric cancer cells treated with MMC (0.1, 0.5 and 2.5 microg/ml) for 24 h were (15.35 +/- 0.77)%, (24.72 +/- 0.83)%, and (30.68 +/- 0.28)%, respectively. There were significant differences among the inhibition rates caused by different concentrations of the drugs (P < 0.05). When 1 micromol/L DMS was used in combination with 5-Fu (1, 5, and 25 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (16.76 +/- 0.41)%, (27.28 +/- 0.29)% and (52.56 +/- 3.60)%, respectively. When 1 micromol/L DMS was used in combination with DDP (0.5, 2.5, and 12.5 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (15.35 +/- 0.86)%, (25.57 +/- 0.27)%, (36.37 +/- 0.51)%, respectively. When 1 micromol/L DMS was used in combination with MMC (0.1, 0.5, and 2.5 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (21.02 +/- 0.28)%, (32.10 +/- 0.27)%, (36.36 +/- 0.28)%, respectively. There were also significant differences among the growth inhibition rates caused by different concentrations of the drugs alone and in combination groups (P < 0.05).. DMS can suppress the proliferation of SGC7901 cells in vitro, and there are evident synergetic effects when it is used in combination with chemotherapeutic drugs. The results of this study indicate that SphK1 inhibitors may become novel and promising chemotherapeutic sensitizers.

Topics: Antibiotics, Antineoplastic; Antimetabolites, Antineoplastic; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cisplatin; Drug Synergism; Enzyme Inhibitors; Fluorouracil; Humans; Mitomycin; Phosphotransferases (Alcohol Group Acceptor); Sphingosine; Stomach Neoplasms

Evidence has pointed to the role of sphingosine in cellular differentiation, cell growth, and apoptosis. The present study investigated sphingosine-induced apoptosis in human gastric cancer cells.. Well differentiated MKN-28 and poorly differentiated MKN-45 human gastric cancer cells were cultured. MTT assay, TUNEL staining, Western blotting, and assay of caspase-3, -8, and -9 activities were carried out in cells transfected with and without the siRNA to silence the protein kinase C (PKC)-δ-targeted gene.. Sphingosine induced apoptosis in MKN-28 cells, with the potential much greater than for MKN-45 cells. Transfection with the siRNA to silence the PKC-δ-targeted gene (PKC-δ siRNA) into MKN-28 cells significantly reduced presence of sphingosine-dependent protein kinase (SDK) in association with reduced PKC-δ expression. Sphingosine-induced apoptosis in MKN-28 cells was prevented by transfecting with the PKC-δ siRNA. Sphingosine promoted SDK production from PKC-δ and increased phosphorylated 14-3-3 protein for MKN-28 cells, but such effects were not found with MKN-45 cells. Moreover, sphingosine perturbed mitochondrial membrane potentials and activated caspase-3 and caspase-9 in MKN-28 cells, which were also inhibited by transfecting with the PKC-δ siRNA.. The results of the present study indicate that sphingosine induces apoptosis in well differentiated MKN-28 human gastric cancer cells by increasing SDK production from PKC-δ, to phosphorylate 14-3- 3 protein, thereby causing disruption of mitochondrial membrane potentials and activating caspase-9 followed by the effector caspase-3.

Topics: 14-3-3 Proteins; Apoptosis; Caspase 3; Caspase 9; Cell Line, Tumor; Enzyme Activation; Gastric Mucosa; Humans; Membrane Potential, Mitochondrial; Phosphotransferases (Alcohol Group Acceptor); Protein Kinase C-delta; Sphingosine; Stomach; Stomach Neoplasms

Sphingosine kinase 1 (Sphk1), a lipid kinase implicated in cell transformation and tumor growth, is overexpressed in gastric cancer and is linked with a poor prognosis. The biological relevance of Sphk1 expression in gastric cancer is unclear. Here, we studied the functional significance of Sphk1 as a novel molecular target for gastric cancer by using an antisense oligonucleotide approach in vitro and in vivo. Gastric cancer cell lines (MKN28 and N87) were treated with Sphk1 with locked nucleic acid-antisense oligonucleotides (LNA-ASO). Sphk1 target regulation, cell growth, and apoptosis were assessed for single-agent Sphk1 LNA-ASO and for combinations with doxorubicin. Athymic nude mice xenografted with gastric cancer cells were treated with Sphk1 LNA and assessed for tumor growth and Sphk1 target regulation, in vivo. In vitro, nanomolar concentrations of Sphk1 LNA-ASO induced an approximately two-fold reduction in Sphk1 mRNA in both the cell lines. This resulted in a 1.6-fold increase in apoptosis and inhibited the growth of gastric cancer cells by more than 50% (P < 0.05). The combination of Sphk1 LNA-ASO with doxorubicin resulted in significant chemosensitization. In vivo, Sphk1 LNA-ASO displayed neither mRNA target regulation in xenografts nor antitumor activity in two independent nude mouse xenograft models. In conclusion, the potent single-agent activity and the synergistic effect of Sphk1 LNA-ASO in combination with chemotherapy in vitro highlight Sphk1 as a biologically relevant molecular target for gastric cancer. Further studies are warranted to overcome the challenge of delivering Sphk1-targeting RNA-therapeutics to solid tumors in vivo.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Doxorubicin; Drug Synergism; Female; Humans; Mice; Mice, Nude; Molecular Targeted Therapy; Oligonucleotides, Antisense; Phosphotransferases (Alcohol Group Acceptor); Stomach Neoplasms; Transfection

To explore the clinical significance of sphingosine kinase 1 (SPHK1) in the invasion, metastasis and prognosis of gastric cancer.. Immunohistochemistry was employed to analyze the expression of SPHK1 in 206 clinicopathologically characterized gastric cancer cases from January 2001 to December 2005 at Zhejiang Provincial People's Hospital.. SPHK1 protein was detected in 3 (7.5%) of 40 human non-tumor mucosa. All samples expressed the protein at a low level. SPHK1 protein was detected in 181 (87.9%) of 206 human gastric cancer cases. An elevated expression of SPHK1 protein was detected in 126 (61.2%) tumors. And SPHK1 protein was up-regulated in gastric cancer lesions compared with adjacent noncancerous tissues (P = 0.001). The expression of SPHK1 was correlated with the depth of invasion, lymph node metastasis, distant metastasis and TNM stage (P = 0.039, 0.003, 0.020, 0.003). In stages I-II and III, the 5-year survival rate of the patients with a high expression of SPHK1 was significantly lower than those with a low expression (53.6% (15/28) vs 68.6% (24/35), 7.8% (6/77) vs 30.8% (12/39), P = 0.009, 0.006). In stage IV, the expression of SPHK1 was not correlated with the 5-year survival rate (P > 0.05). Further multivariate analysis suggested that lymph node metastasis, distant metastasis, TNM stage and the up-regulation of SPHK1 were independent prognostic indicators for gastric cancer.. The expression of SPHK1 in gastric cancer is significantly associated with lymph node metastasis, distant metastasis and a poor prognosis. SPHK1 may become a useful marker of predicting tumor progression and prognosis.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Female; Humans; Lymphatic Metastasis; Male; Middle Aged; Neoplasm Invasiveness; Neoplasm Staging; Phosphotransferases (Alcohol Group Acceptor); Prognosis; Stomach Neoplasms

In MKN1 gastric cancer cells, lysophosphatidic acid (LPA) upregulates expression of sphingosine kinase 1 (SphK1) and its downregulation or inhibition suppresses LPA mediated proliferation. Although LPA activates numerous signaling pathways downstream of its receptors, including extracellular-signal-regulated kinase 1/2, p38, JNK, and Akt, and the transactivation of the epidermal growth factor receptor, pharmacological and molecular approaches demonstrated that only activation of ERK1, in addition to the CCAAT/enhancer-binding protein β transcription factor, is involved in transcriptional upregulation of SphK1 by LPA. Our data implicate ERK1 as an important mediator of LPA signaling leading to upregulation of SphK1 and point to SphK1 and sphingosine-1-phosphate production as potential therapeutic targets in gastric cancer.

Topics: CCAAT-Enhancer-Binding Protein-beta; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Lysophospholipids; Mitogen-Activated Protein Kinase 3; Phosphotransferases (Alcohol Group Acceptor); Protein Kinase Inhibitors; Stomach Neoplasms; Transcription, Genetic; Transcriptional Activation; Up-Regulation

The present study was to investigate the clinical significance of sphingosine kinase 1 (SPHK1), an oncoenzyme, in the development and progression of gastric cancer.. mRNA and protein levels of SPHK1 expression in normal gastric epithelial cells, gastric cancer cell lines, and paired gastric cancer lesions and the adjacent noncancerous tissues were examined using reverse transcription-PCR and Western blotting. Immunohistochemistry was employed to analyze SPHK1 expression in 175 clinicopathologically characterized gastric cancer cases. Statistical analyses were applied to derive prognostic and diagnostic associations.. Levels of SPHK1 mRNA and protein were higher in gastric cancer cell lines than in normal gastric epithelial cells. SPHK1 protein level was up-regulated in gastric cancer lesions compared with that in the paired adjacent noncancerous tissues. Gastric cancer tissues from 115 of 175 (65.7%) patients revealed high level of SPHK1 protein expression in contrast to the undetectable or marginally detectable expression of SPHK1 in the adjacent noncancerous gastric tissues. Significantly different expression levels of SPHK1 were found in patients at different clinical stages (P=0.003), T classification (P=0.035), and M classification (P=0.020). Patients with higher SPHK1 expression had shorter overall survival time, whereas those with lower SPHK1 expression survived longer. Further multivariate analysis suggested that SPHK1 up-regulation was an independent prognostic indicator for the disease.. SPHK1 protein could be a useful marker for the prognosis of gastric cancer. Further study on the potential use of SPHK1 as a therapeutic target is also warranted.

Topics: Adult; Aged; Biomarkers, Tumor; Cell Line, Tumor; Disease Progression; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Middle Aged; Phosphotransferases (Alcohol Group Acceptor); Prognosis; RNA, Messenger; Stomach Neoplasms

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

To investigate whether alphastatin could inhibit human gastric cancer growth and furthermore whether sphingosine kinase (SPK) activity is involved in this process.. Using migration assay, MTT assay and Matrigel assay, the effect of alphastatin on vascular endothelial cells (ECs) was evaluated in vitro. SPK and endothelial differentiation gene (EDG)-1, -3, -5 mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). SPK activity assay was used to evaluate the effect of alphastatin on ECs. Matrigel plug assay in nude mice was used to investigate the effect of alphastatin on angiogenesis in vivo. Female nude mice were subcutaneously implanted with human gastric cancer cells (BGC823) for the tumor xenografts studies. Micro vessel density was analyzed in Factor VIII-stained tumor sections by the immunohistochemical SP method.. In vitro, alphastatin inhibited the migration and tube formation of ECs, but had no effect on proliferation of ECs. RT-PCR analysis demonstrated that ECs expressed SPK and EDG-1, -3, -5 mRNAs. In vivo, alphastatin sufficiently suppressed neovascularization of the tumor in the nude mice. Daily administration of alphastatin produced significant tumor growth suppression. Immunohistochemical studies of tumor tissues revealed decreased micro vessel density in alphastatin-treated animals as compared with controls.. Downregulating ECs SPK activity may be one of the mechanisms that alphastatin inhibits gastric cancer angiogenesis. Alphastatin might be a useful and relatively nontoxic adjuvant therapy in the treatment of gastric cancer.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cells, Cultured; Drug Screening Assays, Antitumor; Endothelium, Vascular; Female; Fibrinogen; Gene Expression Regulation, Enzymologic; Humans; Mice; Mice, Nude; Neovascularization, Pathologic; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; RNA, Messenger; Stomach Neoplasms

To study the interactions between human gastric carcinoma cell (HGCC) and human vascular endothelial cell (HVEC), and if the expression of sphingosine kinase(SPK) gene was involved in these interactions.. The specific inhibitor to SPK, dimethyl sphingosine (DMS), was added acting on HGCC and HVEC, then the cell proliferation was measured by MTT. The conditioned mediums (CMs) of HGCC and HVEC were prepared. The CM of one kind of cell was added to the other kind of cell, and the cell proliferation was measured by MTT. After the action of CM, the cellular expression of SPK gene in mRNA level was detected with in situ hybridization(ISH).. DMS could almost completely inhibit the proliferation of HGCC and HVEC. The growth inhibitory rates could amount to 97.21 %, 83.42 %, respectively (P<0.01). The CM of HGCC could stimulate the growth of HVEC (2.70+/-0.01, P<0.01) while the CM of HVEC could inhibit the growth of HGCC (52.97+/-0.01 %, P<0.01). There was no significant change in the mRNA level of SPK gene in one kind of cell after the action of the CM of the other kind of cell.. SPK plays a key role in regulating the proliferation of HGCC and HVEC. There exist complicated interactions between HGCC and HVEC. HGCC can significantly stimulate the growth of HVEC while HVEC can significantly inhibit the growth of HGCC. The expression of SPK gene is not involved in the interactions.

Topics: Cell Communication; Cell Division; Cell Line; Culture Media, Conditioned; Endothelium, Vascular; Enzyme Inhibitors; Gene Expression; Humans; Phosphotransferases (Alcohol Group Acceptor); RNA, Messenger; RNA, Neoplasm; Sphingosine; Stomach Neoplasms; Tumor Cells, Cultured