3, 3'- (3, 5-DCPBC) Down-Regulates Multiple Phosphokinase Dependent Signal Transduction Pathways in Malignant Melanoma Cells through Specific Diminution of EGFRY1086 Phosphorylation.

Melanoma is the most dangerous skin malignancy due to its strong metastatic potential with high mortality. Activation of crucial signaling pathways enforcing melanoma progression depends on phosphorylation of distinct tyrosine kinases and oxidative stress. We here investigated the effect of a bis-coumarin derivative [3, 3'- ((3″, 5'-Dichlorophenyl) methylene) bis (4-hydroxy-2H-chromen-2-one)] [3, 3'- (3, 5-DCPBC)] on human melanoma cell survival, growth, proliferation, migration, intracellular redox state, and deciphered associated signaling pathways. This derivative is toxic for melanoma cells and non-toxic for melanocytes, their benign counterpart, and fibroblasts. 3, 3'- (3, 5-DCPBC) inhibits cell survival, migration, and proliferation of different metastatic and non-metastatic melanoma cell lines through profound suppression of the phosphorylation of Epidermal Growth Factor receptor (EGFR) and proto-oncogene cellular sarcoma (c-SRC) related downstream pathways. Thus, 3, 3'- (3, 5-DCPBC) endowed with the unique property to simultaneously suppress phosphorylation of multiple downstream kinases, such as EGFR/JAK/STAT and EGFR/SRC and their corresponding transcription factors.

Circ_PIP5K1A regulates cisplatin resistance and malignant progression in non-small cell lung cancer cells and xenograft murine model via depending on miR-493-5p/ROCK1 axis.

BACKGROUND: Chemoresistance limits the therapeutic effect of cisplatin (DDP) on non-small cell lung cancer (NSCLC). Circular RNAs (circRNAs) function as important regulators in chemoresistance. This study aimed to explore the regulation of circRNA Phosphatidylinositol-4-Phosphate 5-Kinase Type 1 Alpha (circ_PIP5K1A) in DDP resistance. METHODS: The expression analysis of circ_PIP5K1A, micoRNA-493-5p (miR-493-5p) and Rho Associated Coiled-Coil Containing Protein Kinase 1 (ROCK1) was conducted through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell sensitivity was determined using 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell proliferation and cell viability were evaluated by colony formation assay and MTT assay, respectively. Cell cycle and apoptosis detection was performed via flow cytometry. Cell motility was examined by transwell migration or invasion assay. Dual-luciferase reporter assay was applied to confirm the target binding. ROCK1 protein level was assayed via Western blot. In vivo assay was carried out using xenograft model in mice. RESULTS: Circ_PIP5K1A level was abnormally increased in DDP-resistant NSCLC tissues and cells. Silencing circ_PIP5K1A reduced DDP resistance, proliferation, cell cycle progression and cell motility in DDP-resistant NSCLC cells. Circ_PIP5K1A directly interacted with miR-493-5p in NSCLC cells. The function of circ_PIP5K1A was dependent on the negative regulation of miR-493-5p. MiR-493-5p directly targeted ROCK1 and circ_PIP5K1A regulated the ROCK1 level via acting as a sponge of miR-493-5p. Overexpression of miR-493-5p inhibited chemoresistance and cancer progression by downregulating ROCK1 expression in DDP-resistant NSCLC cells. Circ_PIP5K1A regulated DDP sensitivity in vivo via the miR-493-5p/ROCK1 axis. CONCLUSION: These findings suggested that circ_PIP5K1A upregulated the ROCK1 expression to promote DDP resistance and cancer progression in NSCLC by sponging miR-493-5p.

Increased SPHK1 and HAS2 Expressions Correlate to Poor Prognosis in Pancreatic Cancer.

OBJECTIVE: SPHK1 and HAS2 have been reported to play important roles in tumorigenesis and development. However, their expression and prognostic value in pancreatic cancer (PC) remain unclear. This study is aimed at investigating the expression of SPHK1 and HAS2 on the prognosis of pancreatic cancer. MATERIALS AND METHODS: The expression of SPHK1 and HAS2 in pancreatic cancer tissues was analyzed through TCGA and GTEx databases and validated by qRT-PCR and Western blot in pancreatic cancer cell lines. χ 2 test was used to explore the correlation of the SPHK1 and HAS2 expressions with clinical characteristics. Kaplan-Meier survival analysis and ROC curve were used to evaluate the prognostic and diagnostic roles of SPHK1 and HAS2 in pancreatic cancer. Additionally, Spearman correlation analysis was applied to assess the correlation between the SPHK1 and HAS2 in pancreatic cancer. GO analysis and KEGG analysis were applied to explore the possible signaling pathway that SPHK1 and HAS2 coregulated genes mediated. RESULTS: The expression of SPHK1 and HAS2 was markedly upregulated in pancreatic cancer tissue and cell lines, respectively. Furthermore, there was a significant positive correlation between SPHK1 and HAS2 expressions. ROC curves showed that SPHK1 combine with HAS2 has good diagnostic value in pancreatic cancer patients with 85% sensitivity and 99.4% specificity. Kaplan-Meier analysis showed that increased expression of SPHK1 and HAS2 was significantly associated with short overall survival (OS) of pancreatic cancer patients. GO and KEGG results revealed that SPHK1 and HAS2 mainly involved cell proliferation and invasion mediated by extracellular matrix- (ECM-) receptor interaction, focal adhesion, and PI3K-AKT signaling pathways. CONCLUSIONS: Overexpression of SPHK1 and HAS2 could be important markers for the prognosis of pancreatic cancer.

Distribution and localization of phosphatidylinositol 5-phosphate, 4-kinase alpha and beta in the brain.

Phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2 ) is critical for synaptic vesicle docking and fusion and generation of the second messengers, diacylglycerol and inositol-1,4,5-trisphosphate. PI-4,5-P2 can be generated by two families of kinases: type 1 phosphatidylinositol-4-phosphate 5-kinases, encoded by PIP5K1A, PIP5K1B and PIP5K1C, and type 2 phosphatidylinositol-5-phosphate 4-kinases, encoded by PIP4K2A, PIP4K2B, and PIP4K2C. While the roles of the type 1 enzymes in brain function have been extensively studied, the roles of the type 2 enzymes are poorly understood. Using selective antibodies validated by genetic deletion of pip4k2a or pip4k2b in mouse brain, we characterized the location of the enzymes, PI5P4Kα and PI5P4Kß, encoded by these genes. In mice, we demonstrate that PI5P4Kα is expressed in adulthood, whereas PI5P4Kß is expressed early in development. PI5P4Kα localizes to white matter tracts, especially the corpus callosum, and at a low level in neurons, while PI5P4Kß is expressed in neuronal populations, especially hippocampus and cortex. Dual labeling studies demonstrate that PI5P4Kα co-localizes with the oligodendrocyte marker, Olig2, whereas PI5P4Kß co-localizes with the neuronal marker, NeuN. Ultrastructural analysis demonstrates that both kinases are contained in axon terminals and dendritic spines adjacent to the synaptic membrane, which support a potential role in synaptic transmission. Immunoperoxidase analysis of macaque and human brain tissue demonstrate a conserved pattern for PI5P4Kα and PI5P4Kß. These results highlight the diverse cell-autonomous expression of PI5P4Kα and PI5P4Kß and support further exploration into their role in synaptic function in the brain.

Undecaprenol kinase: Function, mechanism and substrate specificity of a potential antibiotic target.

The bifunctional undecaprenol kinase/phosphatase (UdpK) is a small, prokaryotic, integral membrane kinase, homologous with Escherichia coli diacylglycerol kinase and expressed by the dgkA gene. In Gram-positive bacteria, UdpK is involved in the homeostasis of the bacterial undecaprenoid pool, where it converts undecaprenol to undecaprenyl phosphate (C55P) and also catalyses the reverse process. C55P is the universal lipid carrier and critical to numerous glycopolymer and glycoprotein biosynthetic pathways in bacteria. DgkA gene expression has been linked to facilitating bacterial growth and survival in response to environmental stressors, as well being implicated as a resistance mechanism to the topical antibiotic bacitracin, by providing an additional route to C55P. Therefore, identification of UdpK inhibitors could lead to novel antibiotic treatments. A combination of homology modelling and mutagenesis experiments on UdpK have been used to identify residues that may be involved in kinase/phosphatase activity. In this review, we will summarise recent work on the mechanism and substrate specificity of UdpK.

Type I Phosphatidylinositol-4-Phosphate 5-Kinases α and γ Play a Key Role in Targeting HIV-1 Pr55Gag to the Plasma Membrane.

HIV-1 assembly occurs principally at the plasma membrane (PM) of infected cells. Gag polyprotein precursors (Pr55Gag) are targeted to the PM, and their binding is mediated by the interaction of myristoylated matrix domain and a PM-specific phosphoinositide, the phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. The major synthesis pathway of PI(4,5)P2 involves the activity of phosphatidylinositol-4-phosphate 5-kinase family type 1 composed of three isoforms (PIP5K1α, PIP5K1ß, and PIP5K1γ). To examine whether the activity of a specific PIP5K1 isoform determines proper Pr55Gag localization at the PM, we compared the cellular behavior of Pr55Gag in the context of PIP5K1 inhibition using siRNAs that individually targeted each of the three isoforms in TZM-bl HeLa cells. We found that downregulation of PIP5K1α and PIP5K1γ strongly impaired the targeting of Pr55Gag to the PM with a rerouting of the polyprotein within intracellular compartments. The efficiency of Pr55Gag release was thus impaired through the silencing of these two isoforms, while PIP5K1ß is dispensable for Pr55Gag targeting to the PM. The PM mistargeting due to the silencing of PIP5K1α leads to Pr55Gag hydrolysis through lysosome and proteasome pathways, while the silencing of PIP5K1γ leads to Pr55Gag accumulation in late endosomes. Our findings demonstrated that, within the PIP5K1 family, only the PI(4,5)P2 pools produced by PIP5K1α and PIP5K1γ are involved in the Pr55Gag PM targeting process.IMPORTANCE PM specificity of Pr55Gag membrane binding is mediated through the interaction of PI(4,5)P2 with the matrix (MA) basic residues. It was shown that overexpression of a PI(4,5)P2-depleting enzyme strongly impaired PM localization of Pr55Gag However, cellular factors that control PI(4,5)P2 production required for Pr55Gag-PM targeting have not yet been characterized. In this study, by individually inhibiting PIP5K1 isoforms, we elucidated a correlation between PI(4,5)P2 metabolism pathways mediated by PIP5K1 isoforms and the targeting of Pr55Gag to the PM of TZM-bl HeLa cells. Confocal microscopy analyses of cells depleted from PIP5K1α and PIP5K1γ show a rerouting of Pr55Gag to various intracellular compartments. Notably, Pr55Gag is degraded by the proteasome and/or by the lysosomes in PIP5K1α-depleted cells, while Pr55Gag is targeted to endosomal vesicles in PIP5K1γ-depleted cells. Thus, our results highlight, for the first time, the roles of PIP5K1α and PIP5K1γ as determinants of Pr55Gag targeting to the PM.

Sphingosine kinase-2 is overexpressed in large granular lymphocyte leukaemia and promotes survival through Mcl-1.

Sphingolipid metabolism is increasingly recognised as a therapeutic target in cancer due to its regulation of cell proliferation and apoptosis. The sphingolipid rheostat is proposed to control cell fate through maintaining balance between pro-apoptotic and pro-survival sphingolipids. This balance is regulated by metabolising enzymes involved in sphingolipid production. One such enzyme, sphingosine kinase-2 (SPHK2), produces pro-survival sphingosine 1-phosphate (S1P) by phosphorylation of pro-apoptotic sphingosine. Elevated SPHK2 has been found in multiple cancer types and contributes to cell survival, chemotherapeutic resistance and apoptosis resistance. We have previously shown elevation of S1P in large granular lymphocyte (LGL) leukaemia serum and cells isolated from patients. Here, we examined SPHK2 expression in LGL leukaemia and found SPHK2 mRNA and protein upregulation in a majority of LGL leukaemia patient samples. Knockdown of SPHK2 with siRNA in LGL leukaemia cell lines decreased proliferation. Additionally, the use of ABC294640 or K145, both SPHK2-specific inhibitors, decreased viability of LGL leukaemia cell lines. ABC294640 selectively induced apoptosis in LGL cell lines and freshly isolated LGL leukaemia patient cells compared to normal controls. Mechanistically, SPHK2 inhibition downregulated pro-survival myeloid cell leukaemia-1 (Mcl-1) protein through proteasomal degradation. Targeting of SPHK2 therefore provides a novel therapeutic approach for the treatment of LGL leukaemia.

The Sphkl/SlP pathway regulates angiogenesis via NOS/NO synthesis following cerebral ischemia-reperfusion.

AIMS: Sphingosine kinase 1 (Sphk1) and the signaling molecule sphingosine-1-phosphate (S1P) are known to be key regulators of a variety of important biological processes, such as neovascularization. Nitric oxide (NO) is also known to play a role in vasoactive properties, whether Sphk1/S1P signaling is able to alter angiogenesis in the context of cerebral ischemia-reperfusion injury (IRI), and whether such activity is linked with NO production, however, remains uncertain. METHODS: We used immunofluorescence to detect the expression of Sphk1 and NOS in cerebral epithelial cells (EC) after IR or oxygen-glucose deprivation (OGDR). Western blotting was used to detect the Sphk1 and NOS protein levels in brain tissues or HBMECs. Adenovirus transfection was used to inhibit Sphk1 and NOS. An NO kit was used to detect NO contents in brain tissues and epithelial cells. Tube formation assays were conducted to measure angiogenesis. RESULTS: We determined that EC used in a model of cerebral IRI expressed Sphk1, and that inhibiting this expression led to decreased expression of two isoforms of NO synthase (eNOS and iNOS), as well as to decrease neovascularization density and NO production following injury. In HBMECs, knocking down Sphk1 markedly reduced NO production owing to reduced eNOS activity, and inhibiting eNOS directly similarly decreased NO production in a manner which could be reversed via exogenously treating cells with S1P. We further found that knocking down Sphk1 reduced HBMEC eNOS expression, in addition to decreasing the adhesion, migration, and tube formation abilities of these cells under OGDR conditions. CONCLUSIONS: Based on these results, we therefore postulate that Sphk1/S1P signaling is able to mediate angiogenesis following cerebral IRI via the regulation of eNOS activity and NO production. As such, targeting these pathways may potentially represent a novel means of improving patient prognosis in those suffering from cerebral IRI.

miRNA-103 promotes chondrocyte apoptosis by down-regulation of Sphingosine kinase-1 and ameliorates PI3K/AKT pathway in osteoarthritis.

OBJECTIVES: The aim of the present study was to determine the effects of miRNA-103 on chondrocyte apoptosis and molecular mechanisms in osteoarthritis (OA) progression. METHODS: The cell proliferation, apoptosis, and recovery ability were measured by cell counting kit-8 (CCK-8), flow cytometry, and wound healing assays. The interaction of miRNA-103 and Sphingosine kinase-1 (SPHK1) were determined by using luciferase reporter assay. The expression of mRNA and proteins were measured by qRT-PCR and Western blot. OA rat model was established by surgery stimulation. RESULTS: miRNA-103 expression was significantly increased in the cartilage of OA patients and surgery-induced OA rat models. miRNA-103 transfection into primary rat chondrocytes reduced SPHK1 expression, induced apoptosis, inhibited cell proliferation, and impeded scratch assay wound closure. Moreover, expression of total AKT, and p-AKT were significantly reduced in miRNA-103-overexpressing chondrocytes while SPHK1 up-regulation increased the expression of phosphatidylinsitol-3-kinase (PI3K) and p-AKT, and reversed the proliferation suppression induced by the miRNA-103 mimic. CONCLUSIONS: Our studies suggest that miRNA-103 contributes to chondrocyte apoptosis, promoting OA progression by down-regulation of PI3K/AKT pathway through the reduction in SPHK1 activity.

miR-199a-3p targets ETNK1 to promote invasion and migration in gastric cancer cells and is associated with poor prognosis.

PURPOSE: To investigate the prognostic significance of miR-199a-3p and its role in invasion and metastasis in gastric cancer. METHODS: miR-199a-3p expression in 436 formalin-fixed and 39 frozen gastric cancer tissues was investigated by in situ hybridization and RT-PCR, respectively. The role of miR-199a-3p in the migration and invasion of gastric cancer cells was determined in overexpression and inhibitor studies using transwell assays and the SGC-7901, BGC-823 and MGC-803 gastric cancer cells lines. The effect of miR-199a-3p expression on ethanolamine kinase 1 (ETNK1) levels was determined by western botting. RESULTS: miR-199a-3p was significantly up-regulated in AGS, SGC-7901, BGC-823 and MGC-803 gastric cancer cells, when compared with GES-1 non-malignant gastric epithelial cells. In situ hybridization studies revealed that human non-tumor gastric mucosa samples were negative for miR-199a-3p expression, while 162 of 436 (37.16%) cases of gastric cancer demonstrated positive expression. miR-199a-3p overexpression was associated with tumor size, Lauren classification, depth of invasion, lymph node and distant metastasis, TNM stage and prognosis. In patients with I, II and III stage tumors, high miR-199a-3p expression was associated with a significantly lower 5-year survival rate. miR-199a-3p overexpression was associated with increased cell migration and invasion. ETNK1 expression was inhibited following miR-199a-3p overexpression in BGC-823 and SGC-7901 cells, and elevated following miR-199a-3p suppression in MGC-803 cells. CONCLUSION: miR-199a-3p is highly expressed in gastric cancer, and correlates with invasion, metastasis and prognosis. miR-199a-3p regulates the invasion and migration of gastric cancer cells by targeting ETNK1. Consequently, miR-199a-3p may serve as a prognostic indicator in gastric cancer.

Resveratrol (3, 5, 4'-Trihydroxy-trans-Stilbene) Attenuates a Mouse Model of Multiple Sclerosis by Altering the miR-124/Sphingosine Kinase 1 Axis in Encephalitogenic T Cells in the Brain.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) (RES) is a naturally-derived phytoestrogen found in the skins of red grapes and berries and has potential as a novel and effective therapeutic agent. In the current study, we investigated the role of microRNA (miRNA) in RES-mediated attenuation of experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. Administration of RES effectively decreased disease severity, including inflammation and central nervous system immune cell infiltration. miRNA microarray analysis revealed an altered miRNA profile in encephalitogenic CD4+ T cells from EAE mice exposed to RES treatment. Additionally, bioinformatics and in silico pathway analysis suggested the involvement of RES-induced miRNA in pathways and processes that regulated cellular proliferation. Additional studies confirmed that RES affected cell cycle progression and apoptosis in activated T cells, specifically in the brain. RES treatment significantly upregulated miR-124 during EAE, while suppressing associated target gene, sphingosine kinase 1 (SK1), and this too was specific to mononuclear cells in the brains of treated mice, as peripheral immune cells remained unaltered upon RES treatment. Collectively, these studies demonstrate that RES treatment leads to amelioration of EAE development through mechanism(s) potentially involving suppression of neuroinflammation via alteration of the miR-124/SK1 axis, thereby halting cell-cycle progression and promoting apoptosis in activated encephalitogenic T cells. Graphical Abstract Resveratrol alters the miR-124/sphingosine kinase 1 (SK1) axis in encephalitogenic T cells, promotes cell-cycle arrest and apoptosis, and decreases neuroinflammation in experiemental autoimmune encephalomyelitis (EAE).

Links between accelerated replicative cellular senescence and down-regulation of SPHK1 transcription.

We have identified a mechanism to diminish the proliferative capacity of cells during cell expansion using human adiposederived stromal cells (hAD-SCs) as a model of replicative senescence. hAD-SCs of high-passage numbers exhibited a reduced proliferative capacity with accelerated cellular senescence. Levels of key bioactive sphingolipids were significantly increased in these senescent hAD-SCs. Notably, the transcription of sphingosine kinase 1 (SPHK1) was down-regulated in hAD-SCs at high-passage numbers. SPHK1 knockdown as well as inhibition of its enzymatic activity impeded the proliferation of hAD-SCs, with concomitant induction of cellular senescence and accumulation of sphingolipids, as seen in high-passage cells. SPHK1 knockdown-accelerated cellular senescence was attenuated by co-treatment with sphingosine-1-phosphate and an inhibitor of ceramide synthesis, fumonisin B1, but not by treatment with either one alone. Together, these results suggest that transcriptional down-regulation of SPHK1 is a critical inducer of altered sphingolipid profiles and enhances replicative senescence during multiple rounds of cell division. [BMB Reports 2019; 52(3): 220-225].

Regulation of ABCA1-mediated cholesterol efflux by sphingosine-1-phosphate signaling in macrophages.

Sphingolipid and cholesterol metabolism are closely associated at the structural, biochemical, and functional levels. Although HDL-associated sphingosine-1-phosphate (S1P) contributes to several HDL functions, and S1P signaling regulates glucose and lipid metabolism, no study has addressed the involvement of S1P in cholesterol efflux. Here, we show that sphingosine kinase (Sphk) activity was induced by the LXR agonist 22(R)-hydroxycholesterol and required for the stimulation of ABCA1-mediated cholesterol efflux to apolipoprotein A-I. In support, pharmacological Sphk inhibition and Sphk2 but not Sphk1 deficiency abrogated efflux. The involved mechanism included stimulation of both transcriptional and functional ABCA1 regulatory pathways and depended for the latter on the S1P receptor 3 (S1P3). Accordingly, S1P3-deficient macrophages were resistant to 22(R)-hydroxycholesterol-stimulated cholesterol efflux. The inability of excess exogenous S1P to further increase efflux was consistent with tonic S1P3 signaling by a pool of constitutively generated Sphk-derived S1P dynamically regulating cholesterol efflux. In summary, we have established S1P as a previously unrecognized intermediate in LXR-stimulated ABCA1-mediated cholesterol efflux and identified S1P/S1P3 signaling as a positive-feedback regulator of cholesterol efflux. This constitutes a novel regulatory mechanism of cholesterol efflux by sphingolipids.

Overexpression of Human Mutant PANK2 Proteins Affects Development and Motor Behavior of Zebrafish Embryos.

Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a genetic and early-onset neurodegenerative disorder characterized by iron accumulation in the basal ganglia. It is due to mutations in Pantothenate Kinase 2 (PANK2), an enzyme that catalyzes the phosphorylation of vitamin B5, first and essential step in coenzyme A (CoA) biosynthesis. Most likely, an unbalance of the neuronal levels of this important cofactor represents the initial trigger of the neurodegenerative process, yet a complete understanding of the connection between PANK2 malfunctioning and neuronal death is lacking. Most PKAN patients carry mutations in both alleles and a loss of function mechanism is proposed to explain the pathology. When PANK2 mutants were analyzed for stability, dimerization capacity, and enzymatic activity in vitro, many of them showed properties like the wild-type form. To further explore this aspect, we overexpressed the wild-type protein, two mutant forms with reduced kinase activity and two retaining the catalytic activity in zebrafish embryos and analyzed the morpho-functional consequences. While the wild-type protein had no effects, all mutant proteins generated phenotypes that partially resembled those observed in pank2 and coasy morphants and were rescued by CoA and vitamin B5 supplementation. The overexpression of PANK2 mutant forms appears to be associated with perturbation in CoA availability, irrespective of their catalytic activity.

Characterizing Sphingosine Kinases and Sphingosine 1-Phosphate Receptors in the Mammalian Eye and Retina.

Sphingosine 1-phosphate (S1P) signaling regulates numerous biological processes including neurogenesis, inflammation and neovascularization. However, little is known about the role of S1P signaling in the eye. In this study, we characterize two sphingosine kinases (SPHK1 and SPHK2), which phosphorylate sphingosine to S1P, and three S1P receptors (S1PR1, S1PR2 and S1PR3) in mouse and rat eyes. We evaluated sphingosine kinase and S1P receptor gene expression at the mRNA level in various rat tissues and rat retinas exposed to light-damage, whole mouse eyes, specific eye structures, and in developing retinas. Furthermore, we determined the localization of sphingosine kinases and S1P receptors in whole rat eyes by immunohistochemistry. Our results unveiled unique expression profiles for both sphingosine kinases and each receptor in ocular tissues. Furthermore, these kinases and S1P receptors are expressed in mammalian retinal cells and the expression of SPHK1, S1PR2 and S1PR3 increased immediately after light damage, which suggests a function in apoptosis and/or light stress responses in the eye. These findings have numerous implications for understanding the role of S1P signaling in the mechanisms of ocular diseases such as retinal inflammatory and degenerative diseases, neovascular eye diseases, glaucoma and corneal diseases.

Transforming Growth Factor ß1 (TGF-ß1) Appears to Promote Coronary Artery Disease by Upregulating Sphingosine Kinase 1 (SPHK1) and Further Upregulating Its Downstream TIMP-1.

BACKGROUND Transforming growth factor (TGF)-ß1 is involved in the pathogenesis of coronary artery disease (CAD), but the mechanism of its action remains unclear. Our study aimed to investigate the role of TGF-ß1 in CAD and to explore the possible mechanisms. MATERIAL AND METHODS A total of 60 CAD patients and 54 healthy people were included in this study. Blood samples were drawn from each participant to prepare serum. ELISA was utilized to measure serum level of TGF-ß1. TGF-ß1 expression vector, TGF-ß1 siRNA, and TIMP-1 siRNA were transfected into human primary coronary artery endothelial cell (HCAEC) line cells, and expression of TGF-ß1 sphingosine kinase 1 (SPHK1) and TIMP metallopeptidase inhibitor 1 (TIMP-1) was detected by Western blot. Cell apoptosis was detected by MTT assay. RESULTS Serum level of TGF-ß1 was specifically higher in patients with CAD than in healthy controls. Serum levels of active TGF-ß1 can be used to effectively distinguish CAD patients from healthy controls. TGF-ß1 overexpression promoted the apoptosis of HCAEC and TGF-ß1 siRNA silencing inhibited the apoptosis of HCAEC. TGF-ß1 overexpression also promoted the expression of SPHK1 and TIMP-1. SPHK1 overexpression upregulated TIMP-1 but it showed no significant effects on TGF-ß1. TIMP-1 overexpression showed no significant effects on TGF-ß1 or SPHK1. SPHK1 inhibitor and TIMP-1 silencing reduced the enhancing effects of TGF-ß1 overexpression on cell apoptosis. CONCLUSIONS TGF-ß1 appears to promote CAD through the induction of cell apoptosis by upregulating SPHK1 expression and further upregulating its downstream TIMP-1.

MiR-363-3p suppresses tumor growth and metastasis of colorectal cancer via targeting SphK2.

Aberrant expression of miR-363-3p is seen in a wide array of cancers. The exact function of miR-363-3p in colorectal cancer (CRC), and the underlying mechanisms remain undefined. In the current study, we observed a down-regulation of miR-363-3p in CRC tissues, along with a strong correlation between low miR-363-3p levels and clinico-pathological parameters like tumor stage and lymph node metastasis. Ectopic overexpression of miR-363-3p in HT29 and HCT116 cell lines effectively inhibited cell proliferation and metastasis, and promoted apoptosis. Concurrently, miR-363-3p inhibition facilitated cell proliferation and suppressed apoptosis. Consistent with the in vitro findings, tumor growth and metastasis were also suppressed by the overexpression of miR-363-3p in vivo. Furthermore, miR-363-3p overexpression resulted in a significant decrease in SphK2 mRNA and protein levels, while miR-363-3p inhibition elevated SphK2 levels in CRC cell lines. Overexpression of SphK2 significantly abrogated the effects of miR-363-3p on cell growth, apoptosis, and metastasis. Taken together, our findings establish miR-363-3p as a potential tumor suppressor in CRC with SphK2 as its downstream target.

Genetic Association and Expression Analyses of the Phosphatidylinositol-4-Phosphate 5-Kinase (PIP5K1C) Gene in Alcohol Use Disorder-Relevance for Pain Signaling and Alcohol Use.

BACKGROUND: The gene encoding phosphatidylinositol-4-phosphate 5-kinase (PIP5K1C) has been recently implicated in pain regulation. Interestingly, a recent cross-tissue and cross-phenotypic epigenetic analysis identified the same gene in alcohol use disorder (AUD). Given the high comorbidity between AUD and chronic pain, we hypothesized that genetic variation in PIP5K1C might contribute to susceptibility to AUD. METHODS: We conducted a case-control association study of genetic variants in PIP5K1C. Association analyses of 16 common PIP5K1C single nucleotide polymorphisms (SNPs) were conducted in cases and controls of African (427 cases and 137 controls) and European ancestry (488 cases and 324 controls) using standard methods. In addition, given the prominent role of the opioid system in pain signaling, we investigated the effects of acute alcohol exposure on PIP5K1C expression in humanized transgenic mice for the µ-opioid receptor that included the OPRM1 A118G polymorphism, a widely used mouse model to study analgesic response to opioids in pain. PIP5K1C expression was measured in the thalamus and basolateral amygdala (BLA) in mice after short-term administration (single 2 g/kg dose) of alcohol or saline using immunohistochemistry and analyzed by 2-way analysis of variance. RESULTS: In the case-control association study using an NIAAA discovery sample, 8 SNPs in PIP5K1C were significantly associated with AUD in the African ancestry (AA) group (p < 0.05 after correction; rs4807493, rs10405681, rs2074957, rs10432303, rs8109485, rs1476592, rs10419980, and rs4432372). However, a replication analysis using an independent sample (N = 3,801) found no significant associations after correction for multiple testing. In the humanized transgenic mouse model with the OPRM1 polymorphism, PIP5K1C expression was significantly different between alcohol and saline-treated mice, regardless of genotype, in both the thalamus (p < 0.05) and BLA (p < 0.01). CONCLUSIONS: Our discovery sample shows that genetic variants in PIP5K1C are associated with AUD in the AA group, and acute alcohol exposure leads to up-regulation of PIP5K1C, potentially explaining a mechanism underlying the increased risk for chronic pain conditions in individuals with AUD.

Triple Negative Breast Cancer Depends on Sphingosine Kinase 1 (SphK1)/Sphingosine-1-Phosphate (S1P)/Sphingosine 1-Phosphate Receptor 3 (S1PR3)/Notch Signaling for Metastasis.

BACKGROUND Triple negative breast cancer (TNBC) has a more aggressive recurrence. Previous reports have demonstrated that sphingosine kinase 1 (SphK1) is a crucial regulator of breast cancer progression. However, the correlation of SphK1 with clinical prognosis has been poorly investigated. Thus, we aimed to elaborate the role of SphK1 in TNBC metastasis. MATERIAL AND METHODS We first determined the level of SphK1 in breast cancer tissue samples and breast cancer cells. Furthermore, the expression of HER2 and phosphor-SphK1 (pSphK1) in human breast cancer tissue samples was determined by immunohistochemical analysis. Associations between SphK1 and clinical parameters of tumors were analyzed. The activity of SphK1 was measured by fluorescence analysis. Extracellular sphingosine-1-phosphate (S1P) was detected using an ELISA kit. Associations between SphK1 and metastasis potential were analyzed by Transwell assay. RESULTS Levels of SphK1 in TNBC patients were significantly higher than levels in other patients with other breast tumors. The expression of SphK1 was positively correlated with poor overall survival (OS) and progression-free survival (PFS), as well as poor response to 5-FU and doxorubicin. The depression of SphK1 thus could repress the Notch signaling pathway, reduce migration, and invasion of TNBC cells in vivo and in vitro. Furthermore, silencing of SphK1 by Ad-SPHK1-siRNA or SphK1 inhibitor PF543 sensitized TNBCs to 5-FU and doxorubicin. Our results also indicated that SphK1 inhibition could effectively counteracts tumors metastasis via Notch signaling pathways, indicating a potentially anti-tumor strategy in TNBC. CONCLUSIONS We found that elevated levels of pSphK1 were positive correlation with high expression of S1P, which in turn promoted metastasis of TNBC through S1P/S1PR3/Notch signaling pathway.