Sphingosine kinase 1 aggravates liver fibrosis by mediating macrophage recruitment and polarization.

BACKGROUND & AIMS: Sphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells (KCs) and hepatic stellate cells (HSCs) in liver fibrosis. Here, we aim to investigate the roles of SphK1 on hepatic macrophage recruitment and polarization in liver fibrosis. METHODS: Liver fibrosis was induced by carbon tetrachloride (CCl4) in wild-type and SphK1-/- mice to study the recruitment and polarization of macrophages. The effects of SphK1 originated from macrophages or other liver cell types on liver fibrosis were further strengthened by bone marrow transplantation (BMT). The direct effects of SphK1 on macrophage polarization were also investigated in vitro. Expression analysis of SphK1 and macrophage polarization index was conducted with human liver samples. RESULTS: SphK1 deletion attenuated the recruitment of hepatic macrophages along with reduced M1 and M2 polarization in mice induced by CCl4. SphK1 deficiency in endogenous liver cells attenuated macrophage recruitment via CCL2. Macrophage SphK1 activated the ASK1-JNK1/2-p38 signaling pathway to promote M1 polarization. Furthermore, macrophage SphK1 downregulated small ubiquitin-like modifier (SUMO) specific peptidase1 (SENP1) to decrease de-SUMOylation of Kruppel-like factor 4 (KLF4) to promote M2 polarization. Finally, we confirmed that SphK1 expression was elevated and positively correlated with macrophage M1 and M2 polarization in human fibrosis livers. CONCLUSIONS: Our findings demonstrated that SphK1 aggravated liver fibrosis by promoting macrophage recruitment and M1/M2 polarization. SphK1 in macrophages is a potential therapeutic target for the treatment of liver fibrosis.

Breast cancer colonization by Malassezia globosa accelerates tumor growth.

Malassezia globosa is a lipophilic basidiomycetous yeast that occurs abundantly in breast tumors and that may contribute to a shortened overall survival of breast cancer (BRAC) patients, suggesting that the yeast may participate in the carcinogenesis of BRAC. However, the mechanisms involved in the M. globosa-based acceleration of BRAC are unknown. Here, we show that M. globosa can colonize mammary tissue in 7,12-dimethylbenz[a] anthracene-induced mice. The abundance of M. globosa shortened the overall survival and increased the tumor incidence. Transcriptome data illustrated that IL-17A plays a key role in tumor growth due to M. globosa colonization, and tumor-associated macrophage infiltration was elevated during M. globosa colonization which triggers M2 polarization of macrophages via toll-like receptors 4/nuclear factor kappa-B (Nf-κB) signaling. Our results show that the expression of sphingosine kinase 1 (Sphk1) is increased in breast tumors after inoculation with M. globosa. Moreover, we discovered that Sphk1-specific small interfering RNA blocked the formation of lipid droplets, which can effectively alleviate the expression of the signal transducer and activator of the transcription 3 (STAT3)/Nf-κB pathway. Taken together, our results demonstrate that M. globosa could be a possible factor for the progression of BRAC. The mechanisms by which M. globosa promotes BRAC development involve the IL-17A/macrophage axis. Meanwhile, Sphk1 overexpression was induced by M. globosa infection, which also promoted the proliferation of MCF-7 cells.IMPORTANCELiterature has suggested that Malassezia globosa is associated with breast tumors; however, this association has not been confirmed. Here, we found that M. globosa colonizes in breast fat pads leading to tumor growth. As a lipophilic yeast, the expression of sphingosine kinase 1 (Sphk1) was upregulated to promote tumor growth after M. globosa colonization. Moreover, the IL-17A/macrophages axis plays a key role in mechanisms involved in the M. globosa-induced breast cancer acceleration from the tumor immune microenvironment perspective.

Concomitant targeting of FLT3 and SPHK1 exerts synergistic cytotoxicity in FLT3-ITD+ acute myeloid leukemia by inhibiting ß-catenin activity via the PP2A-GSK3ß axis.

BACKGROUND: Approximately 25-30% of patients with acute myeloid leukemia (AML) have FMS-like receptor tyrosine kinase-3 (FLT3) mutations that contribute to disease progression and poor prognosis. Prolonged exposure to FLT3 tyrosine kinase inhibitors (TKIs) often results in limited clinical responses due to diverse compensatory survival signals. Therefore, there is an urgent need to elucidate the mechanisms underlying FLT3 TKI resistance. Dysregulated sphingolipid metabolism frequently contributes to cancer progression and a poor therapeutic response. However, its relationship with TKI sensitivity in FLT3-mutated AML remains unknown. Thus, we aimed to assess mechanisms of FLT3 TKI resistance in AML. METHODS: We performed lipidomics profiling, RNA-seq, qRT-PCR, and enzyme-linked immunosorbent assays to determine potential drivers of sorafenib resistance. FLT3 signaling was inhibited by sorafenib or quizartinib, and SPHK1 was inhibited by using an antagonist or via knockdown. Cell growth and apoptosis were assessed in FLT3-mutated and wild-type AML cell lines via Cell counting kit-8, PI staining, and Annexin-V/7AAD assays. Western blotting and immunofluorescence assays were employed to explore the underlying molecular mechanisms through rescue experiments using SPHK1 overexpression and exogenous S1P, as well as inhibitors of S1P2, ß-catenin, PP2A, and GSK3ß. Xenograft murine model, patient samples, and publicly available data were analyzed to corroborate our in vitro results. RESULTS: We demonstrate that long-term sorafenib treatment upregulates SPHK1/sphingosine-1-phosphate (S1P) signaling, which in turn positively modulates ß-catenin signaling to counteract TKI-mediated suppression of FLT3-mutated AML cells via the S1P2 receptor. Genetic or pharmacological inhibition of SPHK1 potently enhanced the TKI-mediated inhibition of proliferation and apoptosis induction in FLT3-mutated AML cells in vitro. SPHK1 knockdown enhanced sorafenib efficacy and improved survival of AML-xenografted mice. Mechanistically, targeting the SPHK1/S1P/S1P2 signaling synergizes with FLT3 TKIs to inhibit ß-catenin activity by activating the protein phosphatase 2 A (PP2A)-glycogen synthase kinase 3ß (GSK3ß) pathway. CONCLUSIONS: These findings establish the sphingolipid metabolic enzyme SPHK1 as a regulator of TKI sensitivity and suggest that combining SPHK1 inhibition with TKIs could be an effective approach for treating FLT3-mutated AML.

Re-positioning of low dose paclitaxel against depressive-like behavior and neuroinflammation induced by lipopolysaccharide in rats: Crosstalk between NLRP3/caspase-1/IL-1ß and Sphk1/S1P/ NF-κB signaling pathways.

AIMS: Depression is a potentially fatal illness affecting millions of individuals worldwide, across all age groups. Neuroinflammation is a key factor in depression development. Paclitaxel (PXL), a well-known chemotherapeutic agent has been used as therapy for several types of cancer. This study aims to evaluate the ameliorative effect of low-dose PXL against lipopolysaccharide (LPS)-induced depression in rats. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were administrated a single dose of LPS (5 mg/kg, i.p.); 2 h later, rats received PXL (0.3 mg/kg, i.p. three times/week) for one week. KEY FINDINGS: Low-dose PXL alleviated LPS-induced depressive-like behavior in rats as evidenced by significantly improving behavioral changes in both forced swim test (FST) and open field test (OFT), successfully mitigated depletion of monoamines (serotonin, norepinephrine, and dopamine), in addition to markedly decreasing lipid peroxidation with antioxidant levels elevation in brain tissues. Low-dose PXL substantially decreased inflammation triggered by LPS in brain tissue via repressing the expression of NLRP3 and its downstream markers level, caspase-1 and IL-1ß jointly with a corresponding decrease in proinflammatory cytokine levels (TNF-α). Furthermore, low-dose PXL remarkably down-regulated Sphk1/S1P signaling pathway. Concurrent with these biochemical findings, there was a noticeable improvement in the brain tissue's histological changes. SIGNIFICANCE: These findings prove the role of low-dose PXL in treatment of LPS-induced neuroinflammation and depressive-like behavior through their anti-depressant, antioxidant and anti-inflammatory actions. The suggested molecular mechanism may entail focusing the interconnection among Sphk1/S1P, and NLRP3/caspase-1/IL-1ß signaling pathways. Hence PXL could be used as a novel treatment against LPS-induced depression.

S1P Signaling Genes as Prominent Drivers of BCR-ABL1-Independent Imatinib Resistance and Six Herbal Compounds as Potential Drugs for Chronic Myeloid Leukemia.

Imatinib (IM), a breakthrough in chronic myeloid leukemia (CML) treatment, is accompanied by discontinuation challenges owing to drug intolerance. Although BCR-ABL1 mutation is a key cause of CML resistance, understanding mechanisms independent of BCR-ABL1 is also important. This study investigated the sphingosine-1-phosphate (S1P) signaling-associated genes (SphK1 and S1PRs) and their role in BCR-ABL1-independent resistant CML, an area currently lacking investigation. Through comprehensive transcriptomic analysis of IM-sensitive and IM-resistant CML groups, we identified the differentially expressed genes and found a notable upregulation of SphK1, S1PR2, and S1PR5 in IM-resistant CML. Functional annotation revealed their roles in critical cellular processes such as proliferation and GPCR activity. Their network analysis uncovered significant clusters, emphasizing the interconnectedness of the S1P signaling genes. Further, we identified interactors such as BIRC3, TRAF6, and SRC genes, with potential implications for IM resistance. Additionally, receiver operator characteristic curve analysis suggested these genes' potential as biomarkers for predicting IM resistance. Network pharmacology analysis identified six herbal compounds-ampelopsin, ellagic acid, colchicine, epigallocatechin-3-gallate, cucurbitacin B, and evodin-as potential drug candidates targeting the S1P signaling genes. In summary, this study contributes to efforts to better understand the molecular mechanisms underlying BCR-ABL1-independent CML resistance. Moreover, the S1P signaling genes are promising therapeutic targets and plausible new innovation avenues to combat IM resistance in cancer clinical care in the future.

SPHK1 Promotes Pancreatic Cancer Lymphangiogenesis Through the Activation of ERK in LECs.

Lymphatic metastasis is related to an unsatisfactory prognosis in pancreatic cancer. Sphingosine kinase 1 (SPHK1) is an oncogene in cancer. However, the potential effect of SPHK1 on the lymphangiogenesis of pancreatic cancer is little known. In this study, the expression level and role of SPHK1 in pancreatic cancer were evaluated to explore the underlying mechanism involved. The expression of SPHK1 and the lymphatic vessel density (LVD) in pancreatic cancer patient tissue were investigated by immunohistochemistry. The role of SPHK1 in lymphangiogenesis was verified in vitro. Elevated expression of SPHK1 was strongly related to high LVD in pancreatic cancer patient tissue. Silencing of SPHK1 in pancreatic cancer cells observably inhibited lymphangiogenesis. Furthermore, the downregulation of SPHK1 markedly attenuated the phosphorylation of extracellular signal-regulated kinase in lymphatic endothelial cells. This study revealed that SPHK1 might play a crucial role in pancreatic cancer lymphangiogenesis.

Influence of SphK1 on Inflammatory Responses in Lipopolysaccharide-Challenged RAW 264.7 Cells.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are serious respiratory disorders caused by a variety of intrapulmonary and extrapulmonary factors. Their incidence is increasing year by year, with high morbidity and mortality rates and lack of effective treatment. Inflammation plays a crucial role in ALI development, with sphingosine kinase 1 (SphK1) being a pivotal enzyme influencing sphingolipid metabolism and participating in inflammatory responses. However, the specific impact and the signaling pathway underlying SphK1 in lipopolysaccharide (LPS)-induced ALI/ARDS are poorly understood. This investigation aimed to explore the influence of SphK1 on inflammation and delve into the mechanistic aspects of inflammation in RAW 264.7 cells during LPS-induced ALI, which is of great importance in providing new targets and strategies for ALI/ARDS treatment.

Kaempferol mitigates sepsis-induced acute lung injury by modulating the SphK1/S1P/S1PR1/MLC2 signaling pathway to restore the integrity of the pulmonary endothelial cell barrier.

Sepsis-induced acute lung injury (SALI) is the common complication of sepsis, resulting in high incidence and mortality rates. The primary pathogenesis of SALI is the interplay between acute inflammation and endothelial barrier damage. Studies have shown that kaempferol (KPF) has anti-sepsis properties. Sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P) signaling pathway's significance in acute lung damage and S1P receptor 1 (S1PR1) agonists potential in myosin light chain 2 (MLC2) phosphorylation are documented. Whether KPF can regulate the SphK1/S1P/S1PR1/MLC2 signaling pathway to protect the lung endothelial barrier remains unclear. This study investigates the KPF's therapeutic effects and molecular mechanisms in repairing endothelial cell barrier damage in both LPS-induced sepsis mice and human umbilical vein endothelial cells (HUVECs). KPF significantly reduced lung tissue damage and showed anti-inflammatory effects by decreasing IL-6 and TNF-α synthesis in the sepsis mice model. Further, KPF administration can reduce the high permeability of the LPS-induced endothelial cell barrier and alleviate lung endothelial cell barrier injury. Mechanistic studies showed that KPF pretreatment can suppress MLC2 hyperphosphorylation and decrease SphK1, S1P, and S1PR1 levels. The SphK1/S1P/S1PR1/MLC2 signaling pathway controls the downstream proteins linked to endothelial barrier damage, and the Western blot (WB) showed that KPF raised the protein levels. These proteins include zonula occludens (ZO)-1, vascular endothelial (VE)-cadherin and Occludin. The present work revealed that in mice exhibiting sepsis triggered by LPS, KPF strengthened the endothelial barrier and reduced the inflammatory response. The SphK1/S1P/S1PR1/MLC2 pathway's modulation is the mechanism underlying this impact.

SphK1 deficiency ameliorates the development of atherosclerosis by inhibiting the S1P/S1PR3/Rhoa/ROCK pathway.

BACKGROUND AND AIMS: S1P is an important factor regulating the function of the vascular endothelial barrier. SphK1 is an important limiting enzyme for the synthesis of S1P. However, the role of the SphK1/S1P-mediated vascular endothelial barrier function in atherosclerosis has not been fully revealed. This study explored the roles and mechanisms of SphK1 on atherosclerosis in vivo and in vitro. METHODS: In vivo, ApoE-/- and SphK1-/-ApoE-/- mice were fed a high-fat diet to induce atherosclerosis. In vitro, ox-LDL induced HUVECs to establish a cell model. Aortic histological changes were measured by H&E staining, Oil Red O staining, EVG staining, Sirius scarlet staining, immunofluorescence, and Evans Blue Assay. Western blotting was performed to explore the specific mechanism. RESULTS: We validated that deficiency of SphK1 resulted in a marked amelioration of atherosclerosis, as indicated by the decreased lipid accumulation, inflammatory factors, oxidative stress, aortic plaque area, inflammatory factor infiltration, VCAM-1 expression, and vascular endothelial permeability. Moreover, deficiency of SphK1 downregulated the expression of aortic S1PR3, Rhoa, ROCK, and F-actin. The results of administration with the SphK1 inhibitor PF-543 and the S1PR3 inhibitor VPC23019 in vitro further confirmed the conclusion that deficiency of SphK1 reduced S1P level and S1PR3 protein expression, inhibited Rhoa/ROCK signaling pathway, regulated protein expression of F-actin, improved vascular endothelial dysfunction and permeability, and exerted anti-atherosclerotic effects. CONCLUSIONS: This study revealed that deficiency of SphK1 relieved vascular endothelial barrier function in atherosclerosis mice via SphK1/S1P/S1PR signaling pathway.

Dihydromyricetin ameliorates diabetic renal fibrosis via regulating SphK1 to suppress the activation of NF-κB pathway.

Dihydromyricetin (DHM) is a flavonoid from vine tea with broad pharmacological benefits, which improve inflammation by blocking the NF-κB pathway. A growing body of research indicates that chronic kidney inflammation is vital to the pathogenesis of diabetic renal fibrosis. Sphingosine kinase-1 (SphK1) is a key regulator of diabetic renal inflammation, which triggers the NF-κB pathway. Hence, we evaluated whether DHM regulates diabetic renal inflammatory fibrosis by acting on SphK1. Here, we demonstrated that DHM effectively suppressed the synthesis of fibrotic and inflammatory adhesion factors like ICAM-1, and VCAM-1 in streptozotocin-treated high-fat diet-induced diabetic mice and HG-induced glomerular mesangial cells (GMCs). Moreover, DHM significantly suppressed NF-κB pathway activation and reduced SphK1 activity and protein expression under diabetic conditions. Mechanistically, the results of molecular docking, molecular dynamics simulation, and cellular thermal shift assay revealed that DHM stably bound to the binding pocket of SphK1, thereby reducing sphingosine-1-phosphate content and SphK1 enzymatic activity, which ultimately inhibited NF-κB DNA binding, transcriptional activity, and nuclear translocation. In conclusion, our data suggested that DHM inhibited SphK1 phosphorylation to prevent NF-κB activation thus ameliorating diabetic renal fibrosis. This supported the clinical use and further drug development of DHM as a potential candidate for treating diabetic renal fibrosis.

MSC Promotes the Secretion of Exosomal lncRNA KLF3-AS1 to Regulate Sphk1 Through YY1-Musashi-1 Axis and Improve Cerebral Ischemia-Reperfusion Injury.

Stroke remains the 3rd leading cause of long-term disability globally. Over the past decade, mesenchymal stem cell (MSC) transplantation has been proven as an effective therapy for ischemic stroke. However, the mechanism of MSC-derived exosomal lncRNAs during cerebral ischemia/reperfusion (I/R) remains ambiguous. The oxygen-glucose deprivation/reoxygenation (OGD/R) and middle cerebral artery occlusion (MCAO) rat model were generated. MSCs were isolated and characterized by flow cytometry and histochemical staining, and MSC exosomes were purified and characterized by transmission electron microscopy, flow cytometry and Western blot. Western blot, RT-qPCR and ELISA assay were employed to examine the expression or secretion of key molecules. CCK-8 and TUNEL assays were used to assess cell viability and apoptosis. RNA immunoprecipitation and RNA pull-down were used to investigate the direct association between krüppel-like factor 3 antisense RNA 1 (KLF3-AS1) and musashi-1(MSI1). Yin Yang 1 (YY1)-mediated transcriptional regulation was assessed by chromatin immunoprecipitation and luciferase assays. The histological changes and immunoreactivity of key molecules in brain tissues were examined by H&E and immunohistochemistry. MSCs were successfully isolated and exhibited directionally differential potentials. MSC exosomal KLF3-AS1 alleviated OGD/R-induced inflammation in SK-N-SH and SH-SY5Y cells via modulating Sphk1. Mechanistical studies showed that MSI1 positively regulated KLF3-AS1 expression through its direct binding to KLF3-AS1. YY1 was identified as a transcription activator of MSI1 in MSCs. Functionally, YY1/MSI1 axis regulated the release of MSC exosomal KLF3-AS1 to modulate sphingosine kinase 1 (Sphk1)/NF-κB pathway, thereby ameliorating OGD/R- or cerebral I/R-induced injury. MSCs promote the release of exosomal KLF3-AS1 to regulate Sphk1 through YY1/MSI axis and improve cerebral I/R injury.

Integrated network pharmacology and metabolomics reveal vascular protective effects of Ilex pubescens on thromboangiitis obliterans.

BACKGROUND: Ilex pubescens Hook. et Arn (IP), traditionally known for its properties of promoting blood circulation, swelling and pain relief, heat clearing, and detoxification, has been used in the treatment of thromboangiitis obliterans (TAO). Despite its traditional applications, the specific mechanisms by which IP exerts its therapeutic effects on TAO remain unclear. AIM OF THE STUDY: This study aims to uncover the underlying mechanisms in the therapeutic effects of IP on TAO, employing network pharmacology and metabolomic approaches. METHODS: In this study, a rat TAO model was established by injecting sodium laurate through the femoral artery, followed by the oral administration of IP for 7 days. Plasma coagulation parameters were measured to assess the therapeutic effects of IP. The potential influence on the femoral artery and gastrocnemius muscle was histopathologically evaluated. Network pharmacology was employed to predict relevant targets and model pathways for TAO. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) was used for the metabolic profile analysis of rat plasma. Immunohistochemistry (IHC) was used to verify the mechanisms by which IP promotes blood circulation in TAO. RESULTS: The study revealed that IP improved blood biochemical function in TAO and played a significant role in vascular protection and maintaining normal blood vessels and gastrocnemius morphologies. Network pharmacology showed that IP compounds play a therapeutic role in modulating lipids and atherosclerosis. Metabolomic analysis revealed that the pathways involved in sphingolipid metabolism and steroid biosynthesis were significantly disrupted. The joint analysis showed a strong correlation between lysophosphatidylcholine and IP components, including triterpenoid and iridoid components, which support the curative action of IP through the modulation of sphingolipid metabolism. Furthermore, decreased expression levels of SPHK1/S1PR1, TNF-α, IL-1ß, and IL-6 were observed in the IP-treated group, suggesting that IP exerts a protective effect on the vasculature primarily by regulating of the SPHK1/S1PR1 signaling pathway. CONCLUSION: In this study, we found that IP protects the vasculature against injury and treats TAO by regulating the steady-state disturbance of the sphingolipid pathway. These findings suggest that IP promotes vasculature by modulating sphingolipid metabolism and SPHK1/S1PR1 signaling pathway and reduce levels of inflammatory factors, offering new insights into its therapeutic potential.

The dual role of 20(S)-protopanaxadiol in alleviating pulmonary fibrosis through the gut-lung axis.

BACKGROUND: Pulmonary Fibrosis (PF) is a progressive lung disease characterized by the diffuse interstitial tissue, leading to severe breathing difficulties. The existing treatment methods are primarily aimed at slowing the progression of the disease, underscoring the urgent need to discover new drug interventions targeting novel sites. The "gut-lung axis" represents a complex bidirectional communication system where the gut microbiota not only influences lung immunity but also responds to lung-derived signals. Recent advances have uncovered that alterations in gut microbiota composition can significantly impact respiratory diseases, offering new insights into their pathogenesis and potential therapeutic approaches. METHODS: This study is based on the fundamental concepts of the lung-gut axis and our previous research, further exploring the potential mechanisms of 20(S)-Protopanaxadiol (PPD) in ginseng against PF. We utilized a bleomycin-induced mouse model of PF and employed metabolomics and 16S rRNA sequencing to investigate the pathways through which PPD regulates the pulmonary fibrosis process via the gut-lung axis. Finally, we employed strategies such as antibiotic-induced microbiota disruption and fecal microbiota transplantation (FMT) to provide a comprehensive perspective on how PPD regulates pulmonary fibrosis through gut microbiota. RESULTS: The results of the bleomycin (BLM) mouse model of PF proved that PPD can directly act on the glycolysis- related metabolic reprogramming process in lung and the AMPK/STING pathway to improve PF. Combined the analysis of gut microbiota and related metabolites, we found that PPD can regulate the process of PF through the gut-lung axis target points G6PD and SPHK1. FMT and antibiotic-induced microbiota disruption further confirmed intermediate effect of gut microbiota in PF process and the treatment of PPD. Our study suggests that PPD can alleviate the process of pulmonary fibrosis either by directly acting on the lungs or by regulating the gut microbiota. CONCLUSION: This study positions PPD as a vanguard in the therapeutic landscape for pulmonary fibrosis, offering a dual mechanism of action that encompasses both modulation of gut microbiota and direct intervention at molecular targets. These insights highlight the immense therapeutic potential of harnessing the gut-lung axis.

TCF12 Transcriptionally Activates SPHK1 to Induce Osteosarcoma Angiogenesis by Promoting the S1P/S1PR4/STAT3 Axis.

Transcription factor 12 (TCF12) is a known oncogene in many cancers. However, whether TCF12 can regulate malignant phenotypes and angiogenesis in osteosarcoma is not elucidated. In this study, we demonstrated increased expression of TCF12 in osteosarcoma tissues and cell lines. High TCF12 expression was associated with metastasis and poor survival rate of osteosarcoma patients. Knockdown of TCF12 reduced the proliferation, migration, and invasion of osteosarcoma cells. TCF12 was found to bind to the promoter region of sphingosine kinase 1 (SPHK1) to induce transcriptional activation of SPHK1 expression and enhance the secretion of sphingosine-1-phosphate (S1P), which eventually resulted in the malignant phenotypes of osteosarcoma cells. In addition, S1P secreted by osteosarcoma cells promoted the angiogenesis of HUVECs by targeting S1PR4 on the cell membrane to activate the STAT3 signaling pathway. These findings suggest that TCF12 may induce transcriptional activation of SPHK1 to promote the synthesis and secretion of S1P. This process likely enhances the malignant phenotypes of osteosarcoma cells and induces angiogenesis via the S1PR4/STAT3 signaling pathway.

Plantaginis semen ameliorates diabetic kidney disease via targeting the sphingosine kinase 1/sphingosine-1-phosphate pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Plantaginis Semen (PS) is widely utilized as a common herb in several Asian countries, particularly China, due to its diuretic, anti-hypertensive, anti-hyperlipidemic, and anti-hyperglycemic properties. Furthermore, it is acknowledged for its ability to mitigate renal complications associated with metabolic syndrome. Despite its extensive usage, there is limited systematic literature elucidating its therapeutic mechanisms, thus emphasizing the necessity for comprehensive investigations in this field. AIM: This study aims to comprehensively evaluate the therapeutical potential of PS in treating diabetic kidney disease (DKD) and to elucidate the underlying mechanisms through in vivo and in vitro models. METHODS: The main composition of PS were characterized using the UPLC-QTOF-MS method. For the in vivo investigation, a mouse model mediated by streptozocin (STZ) associated with a high-fat diet (HFD) and unilateral renal excision was established. The mice were split into 6 groups (n = 8): control group (CON group), DKD group, low-dose of Plantago asiatica L. seed extract group (PASE-L group, 3 g/kg/d), medium-dose of PASE group (PASE-M, 6 g/kg/d), high-dose of PASE group (PASE-H, 9 g/kg/d), and positive drug group (valsartan, VAS group, 12 mg/kg/d). After 8 weeks of treatment, the damage induced by DKD was evaluated by using relevant parameters of urine and blood. Furthermore, indicators of inflammation and factors associated with the SphK1-S1P signaling pathway were investigated. For the in vitro study, the cell line HBZY-1 was stimulated by high glucose (HG), they were then co-cultured with different concentrations of PASE, and the corresponding associated inflammatory and sphingosine kinase 1/sphingosine-1-phosphate (SphK1-S1P) factors were examined. RESULTS: A total of 59 major components in PS were identified, including flavonoids, iridoids, phenylethanol glycosides, guanidine derivatives, and fatty acids. In the mouse model, PS was found to significantly improve body weight, decrease fasting blood glucose (FBG) levels, increased glucose tolerance and insulin tolerance, improved kidney-related markers compared to the DKD group, pathological changes in the kidneys also improved dramatically. These effects showed a dose-dependent relationship, with higher PASE concentrations yielding significantly better outcomes than lower concentrations. However, the effects of the low PASE concentration were not evident for some indicators. In the cellular model, the high dose of PASE suppressed high glucose (HG) stimulated renal mesangial cell proliferation, suppressed inflammatory factors and NF-κB, and decreased the levels of fibrillin-1(FN-1) and collagen IV(ColIV). CONCLUSION: Our results indicate that PS exerts favorable therapeutic effects on DKD, with the possible mechanisms including the inhibition of inflammatory pathways, suppression of mRNA levels and protein expressions of SphK1 and S1P, consequently leading to reduced overexpression of FN-1 and ColIV, thereby warranting further exploration.

A Crosstalk between the Receptor Tyrosine Kinase-Like Orphan Receptors ROR1/2 and S1P Signaling Pathways in Lung Cancer.

OBJECTIVE: Availability of multimodal treatment strategies, including targeted therapies and immunotherapies, have improved the survival of non-small cell lung carcinoma (NSCLC). However, some patients still progress or respond poorly due to inherent resistance, acquired resistance, or lack of druggable driver mutations. Sphingosine-1-phosphate (S1P) and receptor tyrosine kinase-like orphan receptor (ROR1/2) signaling pathways are activated during lung carcinogenesis. METHODS: In this study, we have evaluated the crosstalk of S1P and ROR1/2 signaling pathways in lung cancer cells. RESULTS: S1P treatment of lung cancer cells decreases ROR1 and ROR2 transcript levels. While treatment with PF-543, a pharmacological SphK1 inhibitor or genetic knockdown of SPHK1 by shRNA, raises ROR1 and ROR2. Furthermore, simultaneous inhibition of SphK1 along with ROR1 reduced the migration of lung cancer cells. CONCLUSION: These findings demonstrate the reciprocal regulation of both pathways, suggesting that both pathways have an inverse relation i.e, in the absence of one pathway, another pathway may take charge of the other pathway. Therefore, simultaneously targeting both pathways could serve as a potential therapeutic target for lung cancer treatment.

Sphingolipid metabolism controls mammalian heart regeneration.

Utilization of lipids as energy substrates after birth causes cardiomyocyte (CM) cell-cycle arrest and loss of regenerative capacity in mammalian hearts. Beyond energy provision, proper management of lipid composition is crucial for cellular and organismal health, but its role in heart regeneration remains unclear. Here, we demonstrate widespread sphingolipid metabolism remodeling in neonatal hearts after injury and find that SphK1 and SphK2, isoenzymes producing the same sphingolipid metabolite sphingosine-1-phosphate (S1P), differently regulate cardiac regeneration. SphK2 is downregulated during heart development and determines CM proliferation via nuclear S1P-dependent modulation of histone acetylation. Reactivation of SphK2 induces adult CM cell-cycle re-entry and cytokinesis, thereby enhancing regeneration. Conversely, SphK1 is upregulated during development and promotes fibrosis through an S1P autocrine mechanism in cardiac fibroblasts. By fine-tuning the activity of each SphK isoform, we develop a therapy that simultaneously promotes myocardial repair and restricts fibrotic scarring to regenerate the infarcted adult hearts.

The emerging roles of sphingosine 1-phosphate and SphK1 in cancer resistance: a promising therapeutic target.

Cancer chemoresistance is a problematic dilemma that significantly restrains numerous cancer management protocols. It can promote cancer recurrence, spreading of cancer, and finally, mortality. Accordingly, enhancing the responsiveness of cancer cells towards chemotherapies could be a vital approach to overcoming cancer chemoresistance. Tumour cells express a high level of sphingosine kinase-1 (SphK1), which acts as a protooncogenic factor and is responsible for the synthesis of sphingosine-1 phosphate (S1P). S1P is released through a Human ATP-binding cassette (ABC) transporter to interact with other phosphosphingolipids components in the interstitial fluid in the tumor microenvironment (TME), provoking communication, progression, invasion, and tumor metastasis. Also, S1P is associated with several impacts, including anti-apoptotic behavior, metastasis, mesenchymal transition (EMT), angiogenesis, and chemotherapy resistance. Recent reports addressed high levels of S1P in several carcinomas, including ovarian, prostate, colorectal, breast, and HCC. Therefore, targeting the S1P/SphK signaling pathway is an emerging therapeutic approach to efficiently attenuate chemoresistance. In this review, we comprehensively discussed S1P functions, metabolism, transport, and signaling. Also, through a bioinformatic framework, we pointed out the alterations of SphK1 gene expression within different cancers with their impact on patient survival, and we demonstrated the protein-protein network of SphK1, elaborating its sparse roles. Furthermore, we made emphasis on different machineries of cancer resistance and the tight link with S1P. We evaluated all publicly available SphK1 inhibitors and their inhibition activity using molecular docking and how SphK1 inhibitors reduce the production of S1P and might reduce chemoresistance, an approach that might be vital in the course of cancer treatment and prognosis.

The Oncogenic Lipid Sphingosine-1-Phosphate Impedes the Phagocytosis of Tumor Cells by M1 Macrophages in Diffuse Large B Cell Lymphoma.

BACKGROUND: A total of 30-40% of diffuse large B cell lymphoma (DLBCL) patients will either not respond to the standard therapy or their disease will recur. The first-line treatment for DLBCL is rituximab and combination chemotherapy. This treatment involves the chemotherapy-induced recruitment of tumor-associated macrophages that recognize and kill rituximab-opsonized DLBCL cells. However, we lack insights into the factors responsible for the recruitment and functionality of macrophages in DLBCL tumors. METHODS: We have studied the effects of the immunomodulatory lipid sphingosine-1-phosphate (S1P) on macrophage activity in DLBCL, both in vitro and in animal models. RESULTS: We show that tumor-derived S1P mediates the chemoattraction of both monocytes and macrophages in vitro and in animal models, an effect that is dependent upon the S1P receptor S1PR1. However, S1P inhibited M1 macrophage-mediated phagocytosis of DLBCL tumor cells opsonized with the CD20 monoclonal antibodies rituximab and ofatumumab, an effect that could be reversed by an S1PR1 inhibitor. CONCLUSIONS: Our data show that S1P signaling can modulate macrophage recruitment and tumor cell killing by anti-CD20 monoclonal antibodies in DLBCL. The administration of S1PR1 inhibitors could enhance the phagocytosis of tumor cells and improve outcomes for patients.

Transcriptome and Lipidomic Analysis Suggests Lipid Metabolism Reprogramming and Upregulating SPHK1 Promotes Stemness in Pancreatic Ductal Adenocarcinoma Stem-like Cells.

Cancer stem cells (CSCs) are considered to play a key role in the development and progression of pancreatic ductal adenocarcinoma (PDAC). However, little is known about lipid metabolism reprogramming in PDAC CSCs. Here, we assigned stemness indices, which were used to describe and quantify CSCs, to every patient from the Cancer Genome Atlas (TCGA-PAAD) database and observed differences in lipid metabolism between patients with high and low stemness indices. Then, tumor-repopulating cells (TRCs) cultured in soft 3D (three-dimensional) fibrin gels were demonstrated to be an available PDAC cancer stem-like cell (CSLCs) model. Comprehensive transcriptome and lipidomic analysis results suggested that fatty acid metabolism, glycerophospholipid metabolism, and, especially, the sphingolipid metabolism pathway were mostly associated with CSLCs properties. SPHK1 (sphingosine kinases 1), one of the genes involved in sphingolipid metabolism and encoding the key enzyme to catalyze sphingosine to generate S1P (sphingosine-1-phosphate), was identified to be the key gene in promoting the stemness of PDAC. In summary, we explored the characteristics of lipid metabolism both in patients with high stemness indices and in novel CSLCs models, and unraveled a molecular mechanism via which sphingolipid metabolism maintained tumor stemness. These findings may contribute to the development of a strategy for targeting lipid metabolism to inhibit CSCs in PDAC treatment.