Sphingosine kinase and sphingosine-1-phosphate receptor signaling pathway in inflammatory gastrointestinal disease and cancers: A novel therapeutic target

A comprehensive review of small molecules, targets, and pathways in ulcerative colitis treatment

Ulcerative colitis (UC), a chronic inflammatory bowel disease (IBD), poses significant clinical challenges because of its complex pathophysiology, long-term nature, and the limited efficacy of existing treatments. Small-molecule compounds, particularly those that are able to modulate inflammation-related signaling pathways and, in many cases, occur in nature, offer a promising alternative or supplement to conventional therapies. Studies on molecules for UC therapeutics reported in 1394 publications over the past 30 years were collected from the Web of Science (WOS) database. Only studies that verified therapeutic efficacy through animal experiments were included. Through an analysis of the molecular classes, structures, common targets, and pathways using network pharmacology, we identified 14 classes of compounds, 5 direct-target modules, and 3 crucial downstream pathways. Alkaloids, phenylpropanoids, flavonoids, and terpenes (and their derivatives) appeared most frequently and mainly targeted lipid metabolism, oxidative stress, immune regulation, signaling transduction, and cancer-related pathways. Notably, there has been an increasing trend of applying naturally sourced compounds in both preclinical and clinical trials, especially flavonoids, over the last five years. Although progress in UC research has been made, the majority of studies have focused on the overall therapeutic effects and biomarker alterations, with limited emphasis on the direct targets and underlying mechanisms. These findings highlight the need to explore novel small-molecule therapeutic strategies for UC, focusing on clearly defined targets and precise modes of action.

Colo-Protective Effects of Pentoxifylline Alone or in Combination With Mesalamine in Colitis Through Sphingosine Kinase 1/Sphingosine 1 Phosphate, and Zonula Occuldin 1 Pathways: New Molecular Approach

Multiple signaling pathways have been implicated in the pathogenesis of ulcerative colitis (UC), including Sphingosine Kinase 1 (SPHK)/Sphingosine-1-Phosphate (S1P), AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/NLR family pyrin domain-containing 3 (NLRP3), zonula occludens-1 (ZO-1), and signal transducer and activator of transcription 3 (STAT3). We aimed to investigate the Colo protective and anti-ulcerative effects of pentoxifylline (PTX) in a rat model of UC. Colitis was induced by intracolonic administration of 2 mL of 3% (v/v) acetic acid (AA). Thirty-five rats were randomly assigned to five groups (n = 7 each): normal control, colitis, mesalamine, PTX, and a combination of PTX plus mesalamine. Disease activity was assessed using the disease activity index, colon weight and length measurements, histological examination, and immunohistochemical detection of caspase-3. Colonic tissue homogenates were analyzed for interleukin-6 (IL-6), S1P, SPHK, mTOR, heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), AMPK, and STAT3 levels. Gene expression of ZO-1 and NLRP3 was also evaluated. Intracolonic AA induced marked functional, biochemical, and inflammatory damage to colonic tissue. Treatment with PTX, mesalamine, or their combination significantly attenuated these effects. Specifically, all treatments reduced levels of IL-6, S1P, SPHK, mTOR, STAT3, NLRP3, and caspase-3, while increasing levels of ZO-1, HO-1, Nrf2, and AMPK. The combination treatment group exhibited near-complete restoration of normal colonic architecture, characterized by intact crypt morphology and minimal fibrosis in the lamina propria. PTX attenuated inflammation, apoptosis, and oxidative stress in colitis, supporting its potential as an adjuvant therapy in UC management.

Unveiling gastric precancerous stages: metabolomic insights for early detection and intervention

BACKGROUND

Gastric precancerous lesions (GPL) represent a heterogeneous, multi-stage process that involves transition from a benign to a malignant state. To optimize prevention and intervention strategies, accurate methods must clearly distinguish between precancerous stages and predict progression risks at early stages.

METHODS

The metabolomic profiles of 188 GPL tissues and matched normal tissues were characterized using ultra-high-performance liquid chromatography-tandem mass spectrometry. Both multivariate and univariate statistical analyses were used to identify metabolomic features differentiating normal, atrophic, and intestinal metaplasia states in the stomach, followed by preliminary functional validation.

RESULTS

From experiments conducted on two cohorts, we established a reliable clinical gastric tissue metabolomic map, which clearly distinguished between normal, atrophic, and intestinalized gastric tissues. We then identified metabolic biomarkers that differentiated various GPL stages. Furthermore, key metabolites were validated in in vitro studies. Relative acyl group and glycerophospholipid abundance was higher in normal gastric tissue when compared to GPL, whereas organic acids were more prevalent in precancerous tissues than in normal tissues. A combination of glycerophosphocholine, tiglylcarnitine, malate, sphingosine, and γ-glutamylglutamic acid may serve as powerful biomarkers to distinguish normal tissue from GPL.

CONCLUSION

We used ultra-high-performance liquid chromatography with tandem mass spectrometry to effectively characterize metabolomic profiles in clinical gastric tissue samples. Key metabolites were identified and validated using targeted metabolomics. This study identified the metabolomic profiles of gastric tissues with atrophy and intestinal metaplasia of the gastric mucosa, uncovering and preliminarily validating key metabolites that may be used to assess high-risk populations and diagnose GPL, potentially advancing targeted gastric cancer prevention and treatment efforts.

Current Understanding of Therapeutic and Diagnostic Applications of Exosomes in Pancreatic Cancer

ABSTRACT

Unusual symptoms, rapid progression, lack of reliable early diagnostic biomarkers, and lack of efficient treatment choices are the ongoing challenges of pancreatic cancer. Numerous research studies have demonstrated the correlation between exosomes and various aspects of pancreatic cancer. In light of these facts, exosomes possess the potential to play functional roles in the treatment, prognosis, and diagnosis of the pancreatic cancer. In the present study, we reviewed the most recent developments in approaches for exosome separation, modification, monitoring, and communication. Moreover, we discussed the clinical uses of exosomes as less invasive liquid biopsies and drug carriers and their contribution to the control of angiogenic activity of pancreatic cancer. Better investigation of exosome biology would help to effectively engineer therapeutic exosomes with certain nucleic acids, proteins, and even exogenous drugs as their cargo. Circulating exosomes have shown promise as reliable candidates for pancreatic cancer early diagnosis and monitoring in high-risk people without clinical cancer manifestation. Although we have tried to reflect the status of exosome applications in the treatment and detection of pancreatic cancer, it is evident that further studies and clinical trials are required before exosomes may be employed as a routine therapeutic and diagnostic tools for pancreatic cancer.

Sex Disparity in Cancer: Role of Autophagy and Estrogen Receptors

Autophagy, a cellular process essential for maintaining homeostasis, plays a fundamental role in recycling damaged components and in adapting to stress. The dysregulation of autophagy is implicated in numerous human diseases, including cancer, where it exhibits a dual role as both a suppressor and a promoter, depending on the context and the stage of tumor development. The significant sex differences observed in autophagic processes are determined by biological factors, such as genetic makeup and sex hormones. Estrogens, through their interaction with specific receptors, modulate autophagy and influence tumor progression, therapy resistance, and the immune response to tumors. In females, the escape from X inactivation and estrogen signaling may be responsible for the advantages, in terms of lower incidence and longer survival, observed in oncology. Women often show better responses to traditional chemotherapy, while men respond better to immunotherapy. The action of sex hormones on the immune system could contribute to these differences. However, women experience more severe adverse reactions to anticancer drugs. The estrogen/autophagy crosstalk-involved in multiple aspects of the tumor, i.e., development, progression and the response to therapy-deserves an in-depth study, as it could highlight sex-specific mechanisms useful for designing innovative and gender-tailored treatments from the perspective of precision medicine.

Sphingosine-1-Phosphate Metabolic Pathway in Cancer: Implications for Therapeutic Targets

Cancer biology revolves around understanding how cells undergo uncontrolled proliferation leading to the formation of malignant tumors. Key aspects include self-sufficiency in growth signals, the lack of response to signals of growth inhibition, the evasion of apoptosis, sustained angiogenesis, the evasion of immune response, the capacity to invade and metastasize, and alterations in cellular metabolism. A vast amount of research, which is exponentially growing, over the past few decades highlights the role of sphingolipids in cancer. They act not only as structural membrane components but also as bioactive molecules that regulate cell fate in different physio-pathological conditions. In cancer, sphingolipid metabolism is dysregulated, contributing to tumor progression, metastasis, and drug resistance. In this review, we outline the impact of sphingosine-1-phosphate (S1P) as a key bioactive sphingolipid in cancer. We give an overview of its metabolism summarizing the role of S1P as an intracellular and extracellular mediator through specific plasma membrane receptors in different cancers. We also describe previous findings on how the disruption in the balance between S1P and ceramide (Cer) is common in cancer cells and can contribute to tumorigenesis and resistance to chemotherapy. We finally consider the potential of targeting the metabolic pathways of S1P as well as its receptors and transporters as a promising therapeutic approach in cancer treatments.

DHRS2-induced SPHK1 downregulation contributes to the cell growth inhibition by Trichothecin in colorectal carcinoma

BACKGROUND

Deregulation of lipid metabolism is one of the most prominent metabolic features in cancer. The activation of sphingolipid metabolic pathways affects the proliferation, invasion, angiogenesis, chemoresistance, and immune escape of tumors, including colorectal cancer (CRC). Dehydrogenase/reductase member 2 (DHRS2), which belongs to the short-chain dehydrogenase/reductase (SDR) family, has been reported to participate in the regulation of lipid metabolism and impact on cancer progression. Trichothecin (TCN) is a sesquiterpenoid metabolite originating from an endophytic fungus of the herbal plant Maytenus hookeri Loes. Studies have shown that TCN exerts a broad-spectrum antitumor activity.

METHODS

We evaluated the proliferative ability of CRC cells by CCK8 and colony formation assays. A metabolite profiling using liquid chromatography coupled with mass spectrometry (LC/MS) was adopted to identify the proximal metabolite changes linked to DHRS2 overexpression. RNA stability assay and RNA immunoprecipitation (RIP) experiments were applied to determine the post-transcriptional regulation of SPHK1 expression by DHRS2. We used flow cytometry to detect changes in cell cycle and cell apoptosis of CRC cells in the absence or presence of TCN.

RESULTS

We demonstrate that DHRS2 hampers the sphingosine kinases 1 (SPHK1)/sphingosine 1-phosphate (S1P) metabolic pathway to inhibit CRC cell growth. DHRS2 directly binds to SPHK1 mRNA to accelerate its degradation in a post-transcriptionally regulatory manner. Moreover, we illustrate that SPHK1 downregulation induced by DHRS2 contributes to TCN-induced growth inhibition of CRC.

CONCLUSIONS

The present study provides a mechanistic connection among metabolic enzymes, metabolites, and the malignant progression of CRC. Moreover, TCN could be developed as a potential pharmacological tool against CRC by the induction of DHRS2 and targeting SPHK1/S1P metabolic pathway.

The role of ACER2 in intestinal sphingolipid metabolism and gastrointestinal cancers

Sphingolipids, particularly sphingosine-1-phosphate (S1P), are bioactive lipids involved in regulating cellular processes such as proliferation, apoptosis, inflammation, and tumor progression. Alkaline ceramidase 2 (ACER2) plays a critical role in sphingolipid metabolism by catalyzing the hydrolysis of ceramide to sphingosine, which is subsequently converted to S1P. Dysregulation of ACER2 has been implicated in various gastrointestinal cancers, including colorectal cancer, gastric cancer, and hepatocellular carcinoma. ACER2-mediated sphingolipid signaling, particularly through the SphK/S1P pathway, influences cancer development by modulating immune responses, inflammation, and the balance between cell survival and death. This review examines the physiological functions of ACER2, and its role in sphingolipid metabolism, and its contribution to the pathogenesis of gastrointestinal cancers. Understanding the mechanisms by which ACER2 regulates tumor progression and immune modulation may open new avenues for targeted therapies in gastrointestinal malignancies.

Protective Role of Sphingosine-1-Phosphate During Radiation-Induced Testicular Injury

The impact of ionizing radiation on the male reproductive system is gaining increasing attention, particularly when it comes to testicular damage, which may result in decreased sperm quality and hormonal imbalances. Finding effective protective measures to mitigate testicular damage caused by radiation has become a focal point in the biomedical field. S1P, an essential biological signaling molecule, has garnered significant interest due to its multiple roles in regulating cellular functions and its protective effects against radiation-induced testicular injury. S1P not only effectively reduces the generation of ROS induced by radiation but also alleviates oxidative stress by enhancing the activity of antioxidant enzymes. Furthermore, S1P inhibits radiation-induced cell apoptosis by regulating the expression of anti-apoptotic and pro-apoptotic proteins. Additionally, S1P alleviates radiation-induced inflammation by inhibiting the production of inflammatory factors, thereby further protecting testicular tissue. In summary, S1P effectively reduces radiation-induced testicular damage through multiple mechanisms, offering a promising therapeutic approach to safeguard male reproductive health. Future research should explore the specific mechanisms of action and clinical application potential of S1P, aiming to contribute significantly to the prevention and treatment of radiation damage.

Targeting sphingosine 1-phosphate and sphingosine kinases in pancreatic cancer: mechanisms and therapeutic potential

Pancreatic cancer is known to be the most lethal cancer. Fewer new treatments are being developed for pancreatic cancer as compared to other cancers. The bioactive lipid S1P, which is mainly regulated by sphingosine kinase 1 (SK1) and sphingosine kinase 2 (SK2) enzymes, plays significant roles in pancreatic cancer initiation and exacerbation. S1P controls many signaling pathways to modulate the progression of pancreatic cancer through the G-coupled receptor S1PR1-5. Several papers reporting amelioration of pancreatic cancer via modulation of S1P levels or downstream signaling pathways have previously been published. In this paper, for the first time, we have reviewed the results of previous studies to understand how S1P and its receptors contribute to the development of pancreatic cancer, and whether S1P can be a therapeutic target. In addition, we have also reviewed papers dealing with the effects of SK1 and SK2, which are kinases that regulate the level of S1P, on the pathogenesis of pancreatic cancer. We have also listed available drugs that particularly focus on S1P, S1PRs, SK1, and SK2 for the treatment of pancreatic cancer. Through this review, we would like to suggest that the SK/S1P/S1PR signaling system can be an important target for treating pancreatic cancer, where a new treatment target is desperately warranted.

Role of Sphingosine-1-Phosphate Signaling Pathway in Pancreatic Diseases

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolic product produced via the phosphorylation of sphingosine by sphingosine kinases (SPHKs), serving as a powerful modulator of various cellular processes through its interaction with S1P receptors (S1PRs). Currently, this incompletely understood mechanism in pancreatic diseases including pancreatitis and pancreatic cancer, largely limits therapeutic options for these disorders. Recent evidence indicates that S1P significantly contributes to pancreatic diseases by modulating inflammation, promoting pyroptosis in pancreatic acinar cells, regulating the activation of pancreatic stellate cells, and affecting organelle functions in pancreatic cancer cells. Nevertheless, no review has encapsulated these advancements. Thus, this review compiles information about the involvement of S1P signaling in exocrine pancreatic disorders, including acute pancreatitis, chronic pancreatitis, and pancreatic cancer, as well as prospective treatment strategies to target S1P signaling for these conditions. The insights presented here possess the potential to offer valuable guidance for the implementation of therapies targeting S1P signaling in various pancreatic diseases.

Characterization of macrophages associated with human skin models exposed to UV radiation

Skin macrophages play important roles in the response to external stimuli. Human skin equivalents (HSEs) incorporating the human monocytic cell line THP-1 were fabricated to generate immunocompetent human skin models. These HSEs were used to investigate the influence of the skin microenvironment and ultraviolet A (UVA) on macrophages. Transcriptomic analysis revealed that THP-1 cells in HSEs were enriched in extracellular matrix interaction hallmark but downregulated in DNA replication hallmark. Upon UVA exposure, immunocompetent HSEs presented epidermal distortion and increased DNA double-strand breaks (DSBs). The genes associated with oxidative stress and the inflammatory response were significantly upregulated in THP-1 cells. When the photoprotective agent mycosporine-2-glycine from cyanobacteria was applied to HSEs, the incidence of UVA-induced DSBs was significantly lower, and inflammatory and UV response hallmarks were downregulated in THP-1 cells. Taken together, these results suggest that immunocompetent HSEs can be used to investigate the responses of skin-resident macrophages to external stimuli.

Mapping network connection and direction among symptoms of depression and anxiety in patients with chronic gastritis

Regarding neurophysiological and developmental findings, anxiety and depression are usual comorbidities of gastritis patients. However, research related to anxiety and depression among chronic gastritis patients was conducted on the disease level while ignoring symptoms. Hence, we rendered the network approach to reveal the symptoms of anxiety and depression among chronic gastritis patients. Three hundred and sixty-nine chronic gastritis patients (female = 139, Mage = 55.87 years) were asked to complete the Self-Rating Anxiety Scale and Self-Rating Depression Scale. Three symptom networks and one directed acyclic graph (DAG) network were formed. First, in the anxiety network of chronic gastritis patients, dizziness was the most influential symptom. In the depression network of chronic gastritis patients, depressed affect and psychomotor retardation were the influential symptoms. Second, panic, easy fatiguability, weakness, palpitation, depressed affect, tachycardia, fatigue, and psychomotor agitation bridged the anxiety-depression network of chronic gastritis patients. Third, DAG networks showed that anxiousness and hopelessness could trigger other symptoms in the anxiety-depression networks of chronic gastritis patients. The current study provided insightful information on patients with chronic gastritis by examining the structures of symptoms.

Repurposing metformin as adjuvant therapy in patients with ulcerative colitis treated with mesalamine: A randomized controlled double-blinded study

BACKGROUND

Ulcerative colitis (UC) is a type of inflammatory bowel disease associated with persistent inflammation. Animal studies proved the efficacy of metformin in UC.

AIM

To investigate the potential role of metformin and its protective pathways in patients with UC.

METHODS

This is a randomized, controlled, and double-blinded clinical trial that included 60 participants with mild to moderate UC and was divided randomly into two groups (n = 30). For 6 months, the mesalamine group received 1 g of mesalamine three times daily (t.i.d.). For six months, the metformin group received mesalamine 1 g t.i.d. and metformin 500 mg twice daily. A gastroenterologist evaluated patients at baseline and 6 months after starting the treatment in order to measure serum levels of zonulin, sphingosine 1 phosphate (S1P), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Biopsies from the colon were used to measure gene expression of zonula occuldin-1 (ZO-1), signal transducer and activator of factor-3 (STAT-3), and intracellular adhesion molecule-1 (ICAM-1). The numeric pain rating scale (NRS) and partial Mayo score were also assessed for each patient.

RESULTS

When compared to the mesalamine group, the metformin group demonstrated a statistical decrease in serum IL-6, zonulin, TNF-α, SIP, gene expression of ICAM-1 and STAT-3, and a significant increase in colonic ZO-1 when compared to the mesalamine group. The metformin group also showed a significant decrease in NRS and partial Mayo score index in comparison with the mesalamine group.

CONCLUSION

Metformin may be a promising additional therapy for UC patients. Trial registration identifier: NCT05553704.

Bioactive sphingolipids as emerging targets for signal transduction in cancer development

Sphingolipids, crucial components of cellular membranes, play a vital role in maintaining cellular structure and signaling integrity. Disruptions in sphingolipid metabolism are increasingly implicated in cancer development. Key bioactive sphingolipids, such as ceramides, sphingosine-1-phosphate (S1P), ceramide-1-phosphate (C1P), and glycosphingolipids, profoundly impact tumor biology. They influence the behavior of tumor cells, stromal cells, and immune cells, affecting tumor aggressiveness, angiogenesis, immune modulation, and extracellular matrix remodeling. Furthermore, abnormal expression of sphingolipids and their metabolizing enzymes modulates the secretion of tumor-derived extracellular vesicles (TDEs), which are key players in creating an immunosuppressive tumor microenvironment, remodeling the extracellular matrix, and facilitating oncogenic signaling within in situ tumors and distant pre-metastatic niches (PMNs). Understanding the role of sphingolipids in the biogenesis of tumor-derived extracellular vesicles (TDEs) and their bioactive contents can pave the way for new biomarkers in cancer diagnosis and prognosis, ultimately enhancing comprehensive tumor treatment strategies.

S1P/S1PR1 signaling is involved in the development of nociceptive pain

Background

Pain is a complex perception involving unpleasant somatosensory and emotional experiences. However, the underlying mechanisms that mediate its different components remain unclear. Sphingosine-1-phosphate (S1P), a metabolite of sphingomyelin and a potent lipid mediator, initiates signaling via G protein-coupled receptors (S1PRs) on cell surfaces. It serves as a second messenger in cellular processes such as proliferation and apoptosis. Nevertheless, the neuropharmacology of sphingolipid signaling in pain conditions within the central nervous system remains largely unexplored and controversial.

Methods

Chronic nociceptive pain models were induced in vivo by intraplantar injection of 20 μL complete Freund's adjuvant (CFA) into the left hind paws. We assessed S1P and S1PR1 expression in the spinal cords of CFA model mice. Functional antagonists of S1PR1 or S1PR1-specific siRNA were administered daily following CFA model establishment. Paw withdrawal response frequency (PWF) and paw withdrawal latency (PWL) were measured to evaluate mechanical allodynia and thermal hyperalgesia, respectively. RT-PCR assessed interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α levels. Western blotting and immunofluorescence were used to analyze glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule (Iba1), STAT3, ERK, and p38 MAPK protein expression.

Results

In the chronic nociceptive pain model induced by CFA, S1P and S1PR1 expression levels were significantly elevated, leading to activation of spinal cord glial cells. S1PR1 activation also promoted MMP2-mediated cleavage of mature IL-1β. Additionally, S1PR1 activation upregulated phosphorylation of STAT3, ERK, and p38 MAPK in glial cells, profoundly impacting downstream signaling pathways and contributing to chronic nociceptive pain.

Conclusion

The S1P/S1PR1 axis plays a pivotal role in the cellular and molecular mechanisms underlying nociceptive pain. This signaling pathway modulates glial cell activation and the expression of pain-related genes (STAT3, ERK, p38 MAPK) and inflammatory factors in the spinal dorsal horn. These findings underscore the potential of targeting the S1P system for developing novel analgesic therapies.

Synergistic anticancer effects of doxorubicin and metformin combination therapy: A systematic review

INTRODUCTION

Doxorubicin (DOX) a chemotherapy drug often leads to the development of resistance, in cancer cells after prolonged treatment. Recent studies have suggested that using metformin plus doxorubicin could result in synergic effects. This study focuses on exploring the co-treat treatment of doxorubicin and metformin for various cancers.

METHOD

Following the PRISMA guidelines we conducted a literature search using different databases such as Embase, Scopus, Web of Sciences, PubMed, Science Direct and Google Scholar until July 2023. We selected search terms based on the objectives of this study. After screening a total of 30 articles were included.

RESULTS

The combination of doxorubicin and metformin demonstrated robust anticancer effects, surpassing the outcomes of monotherapy drug treatment. In vitro experiments consistently demonstrated inhibition of cancer cell growth and increased rates of cell death. Animal studies confirmed substantial reductions in tumor growth and improved survival rates, emphasizing the synergistic impact of the combined therapy. The research' discoveries collectively emphasize the capability of the co-treat doxorubicin-metformin as a compelling approach in cancer treatment, highlighting its potential to address medicate resistance and upgrade generally helpful results.

CONCLUSION

The findings of this study show that the combined treatment regimen including doxorubicin and metformin has significant promise in fighting cancer. The observed synergistic effects suggest that this combination therapy could be valuable, in a setting. This study highlights the need for clinical research to validate and enhance the application of the doxorubicin metformin regimen.

Signaling controversy and future therapeutical perspectives of targeting sphingolipid network in cancer immune editing and resistance to tumor necrosis factor-α immunotherapy

Anticancer immune surveillance and immunotherapies trigger activation of cytotoxic cytokine signaling, including tumor necrosis factor-α (TNF-α) and TNF-related apoptosis-inducing ligand (TRAIL) pathways. The pro-inflammatory cytokine TNF-α may be secreted by stromal cells, tumor-associated macrophages, and by cancer cells, indicating a prominent role in the tumor microenvironment (TME). However, tumors manage to adapt, escape immune surveillance, and ultimately develop resistance to the cytotoxic effects of TNF-α. The mechanisms by which cancer cells evade host immunity is a central topic of current cancer research. Resistance to TNF-α is mediated by diverse molecular mechanisms, such as mutation or downregulation of TNF/TRAIL receptors, as well as activation of anti-apoptotic enzymes and transcription factors. TNF-α signaling is also mediated by sphingosine kinases (SphK1 and SphK2), which are responsible for synthesis of the growth-stimulating phospholipid, sphingosine-1-phosphate (S1P). Multiple studies have demonstrated the crucial role of S1P and its transmembrane receptors (S1PR) in both the regulation of inflammatory responses and progression of cancer. Considering that the SphK/S1P/S1PR axis mediates cancer resistance, this sphingolipid signaling pathway is of mechanistic significance when considering immunotherapy-resistant malignancies. However, the exact mechanism by which sphingolipids contribute to the evasion of immune surveillance and abrogation of TNF-α-induced apoptosis remains largely unclear. This study reviews mechanisms of TNF-α-resistance in cancer cells, with emphasis on the pro-survival and immunomodulatory effects of sphingolipids. Inhibition of SphK/S1P-linked pro-survival branch may facilitate reactivation of the pro-apoptotic TNF superfamily effects, although the role of SphK/S1P inhibitors in the regulation of the TME and lymphocyte trafficking should be thoroughly assessed in future studies.

Cotton sphingosine kinase GhLCBK1 participates in fiber cell elongation by affecting sphingosine-1-phophate and auxin synthesis

Sphingolipids serve as essential components of biomembrane and possess significant bioactive properties. Sphingosine-1-phophate (S1P) plays a key role in plant resistance to stress, but its specific impact on plant growth and development remains to be fully elucidated. Cotton fiber cells are an ideal material for investigating the growth and maturation of plant cells. In this study, we examined the content and composition of sphingosine (Sph) and S1P throughout the progression of fiber cell development. The content of S1P elevated gradually during fiber elongation but declined during the transition stage. Exogenous application of S1P promoted fiber elongation while using of FTY720 (an antagonist of S1P), and DMS (an inhibitor of LCBK) hindered fiber elongation. Cotton Long Chain Base Kinase 1 (GhLCBK1) was notably expressed during the fiber elongation stage, containing all conserved domains of LCBK protein and localized in the endoplasmic reticulum. Overexpression GhLCBK1 increased the S1P content and promoted fiber elongation while retarded secondary cell wall (SCW) deposition. Conversely, downregulation of GhLCBK1 reduced the S1P levels, and suppressed fiber elongation, and accelerated SCW deposition. Transcriptome analysis revealed that upregulating GhLCBK1 or applying S1P induced the expression of GhEXPANSIN and auxin related genes. Furthermore, the levels of IAA were elevated and reduced in the fibers when up-regulating or down-regulating GhLCBK1, respectively. Our investigation demonstrated that GhLCBK1 and its product S1P facilitated the elongation of fiber cells by affecting auxin biosynthesis. This study contributes novel insights into the intricate regulatory pathways involved in fiber cell elongation, identifying GhLCBK1 as a potential target gene and laying the groundwork for enhancing fiber quality via genetic manipulation.

Targeting Sphingosine-1-Phosphate Signaling in Breast Cancer

In recent years, newly emerging therapies, such as immune checkpoint inhibitors and antibody-drug conjugates, have further improved outcomes for breast cancer patients. However, recurrent and metastatic breast cancer often eventually develops resistance to these drugs, and cure is still rare. As such, the development of new therapies for refractory breast cancer that differ from conventional mechanisms of action is necessary. Sphingosine-1-phosphate (S1P) is a key molecule with a variety of bioactive activities, including involvement in cancer cell proliferation, invasion, and metastasis. S1P also contributes to the formation of the cancer microenvironment by inducing surrounding vascular- and lymph-angiogenesis and regulating the immune system. In this article, we outline the basic mechanism of action of S1P, summarize previous findings on the function of S1P in cancer cells and the cancer microenvironment, and discuss the clinical significance of S1P in breast cancer and the therapeutic potential of targeting S1P signaling.

SAA1 regulated by S1P/S1PR1 promotes the progression of ESCC via β-catenin activation

Serum amyloid A1 (SAA1), an inflammation-related molecule, is associated with the malignant progression of many tumors. This study aimed to investigate the role of SAA1 in the progression of esophageal squamous cell carcinoma (ESCC) and its molecular mechanisms. The expression of SAA1 in ESCC tissues and cell lines was analyzed using bioinformatics analysis, western blotting, and reverse transcription-quantitative PCR (RT‒qPCR). SAA1-overexpressing or SAA1-knockdown ESCC cells were used to assess the effects of SAA1 on the proliferation, migration, apoptosis of cancer cells and the growth of xenograft tumors in nude mice. Western blotting, immunofluorescence and RT‒qPCR were used to investigate the relationship between SAA1 and β-catenin and SAA1 and sphingosine 1-phosphate (S1P)/sphingosine 1-phosphate receptor 1 (S1PR1). SAA1 was highly expressed in ESCC tissues and cell lines. Overexpression of SAA1 significantly promoted the proliferation, migration and the growth of tumors in nude mice. Knockdown of SAA1 had the opposite effects and promoted the apoptosis of ESCC cells. Moreover, SAA1 overexpression promoted the phosphorylation of β-catenin at Ser675 and increased the expression levels of the β-catenin target genes MYC and MMP9. Knockdown of SAA1 had the opposite effects. S1P/S1PR1 upregulated SAA1 expression and β-catenin phosphorylation at Ser675 in ESCC cells. In conclusion, SAA1 promotes the progression of ESCC by increasing β-catenin phosphorylation at Ser675, and the S1P/S1PR1 pathway plays an important role in its upstream regulation.

How do sphingosine-1-phosphate affect immune cells to resolve inflammation?

Inflammation is an important immune response of the body. It is a physiological process of self-repair and defense against pathogens taken up by biological tissues when stimulated by damage factors such as trauma and infection. Inflammation is the main cause of high morbidity and mortality in most diseases and is the physiological basis of the disease. Targeted therapeutic strategies can achieve efficient toxicity clearance at the inflammatory site, reduce complications, and reduce mortality. Sphingosine-1-phosphate (S1P), a lipid signaling molecule, is involved in immune cell transport by binding to S1P receptors (S1PRs). It plays a key role in innate and adaptive immune responses and is closely related to inflammation. In homeostasis, lymphocytes follow an S1P concentration gradient from the tissues into circulation. One widely accepted mechanism is that during the inflammatory immune response, the S1P gradient is altered, and lymphocytes are blocked from entering the circulation and are, therefore, unable to reach the inflammatory site. However, the full mechanism of its involvement in inflammation is not fully understood. This review focuses on bacterial and viral infections, autoimmune diseases, and immunological aspects of the Sphks/S1P/S1PRs signaling pathway, highlighting their role in promoting intradial-adaptive immune interactions. How S1P signaling is regulated in inflammation and how S1P shapes immune responses through immune cells are explained in detail. We teased apart the immune cell composition of S1P signaling and the critical role of S1P pathway modulators in the host inflammatory immune system. By understanding the role of S1P in the pathogenesis of inflammatory diseases, we linked the genomic studies of S1P-targeted drugs in inflammatory diseases to provide a basis for targeted drug development.

The Sphingolipid-Modulating Drug Opaganib Protects against Radiation-Induced Lung Inflammation and Fibrosis: Potential Uses as a Medical Countermeasure and in Cancer Radiotherapy

Fibrosis is a chronic pathology resulting from excessive deposition of extracellular matrix components that leads to the loss of tissue function. Pulmonary fibrosis can follow a variety of diverse insults including ischemia, respiratory infection, or exposure to ionizing radiation. Consequently, treatments that attenuate the development of debilitating fibrosis are in desperate need across a range of conditions. Sphingolipid metabolism is a critical regulator of cell proliferation, apoptosis, autophagy, and pathologic inflammation, processes that are all involved in fibrosis. Opaganib (formerly ABC294640) is the first-in-class investigational drug targeting sphingolipid metabolism for the treatment of cancer and inflammatory diseases. Opaganib inhibits key enzymes in sphingolipid metabolism, including sphingosine kinase-2 and dihydroceramide desaturase, thereby reducing inflammation and promoting autophagy. Herein, we demonstrate in mouse models of lung damage following exposure to ionizing radiation that opaganib significantly improved long-term survival associated with reduced lung fibrosis, suppression of granulocyte infiltration, and reduced expression of IL-6 and TNFα at 180 days after radiation. These data further demonstrate that sphingolipid metabolism is a critical regulator of fibrogenesis, and specifically show that opaganib suppresses radiation-induced pulmonary inflammation and fibrosis. Because opaganib has demonstrated an excellent safety profile during clinical testing in other diseases (cancer and COVID-19), the present studies support additional clinical trials with this drug in patients at risk for pulmonary fibrosis.

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.

Accumulation of sphingosine kinase 2 protein induces malignant transformation in oral keratinocytes associated with stemness, autophagy, senescence, and proliferation

Sphingosine-1-phosphate (S1P) signaling has been widely explored as a therapeutic target in cancer. Sphingosine kinase 2 (SK2), one of the kinases that phosphorylate sphingosine, has a cell type and cell location-dependent mechanism of action, so the ability of SK2 to induce cell cycle arrest, apoptosis, proliferation, and survival is strongly influenced by the cell-context. In contrast to SK1, which is widely studied in different types of cancer, including head and neck cancer, the role of SK2 in the development and progression of oral cancer is still poorly understood. In order to elucidate SK2 role in oral cancer, we performed the overexpression of SK2 in non-tumor oral keratinocyte cell (NOK SK2) and in oral squamous cell carcinoma (HN12 SK2), and RNA interference for SK2 in another oral squamous cell carcinoma (HN13 shSK2). In our study we demonstrate for the first time that accumulation of SK2 can be a starting point for oncogenesis and transforms a non-tumor oral keratinocyte (NOK-SI) into highly aggressive tumor cells, even acting on cell plasticity. Furthermore, in oral metastatic cell line (HN12), SK2 contributed even more to the tumorigenesis, inducing proliferation and tumor growth. Our work reveals the intriguing role of SK2 as an oral tumor promoter and regulator of different pathways and cellular processes.

Sphingosine 1-phosphate combining with S1PR4 promotes regulatory T cell differentiation related to FAO through Nrf2/PPARα

Metabolism and metabolic processes have long been considered to shape the tumour immunosuppressive microenvironment. Recent research has demonstrated that T regulatory cells (Tregs) display high rates of fatty acid oxidation (FAO) and a relatively low rate of glycolysis. Sphingosine 1-phosphate (S1P), which is a G protein signalling activator involved in immune regulation and FAO modulation, has been implicated in Treg differentiation. However, the precise relation between Treg differentiation and S1P remains unclear. In this study, we isolated naïve CD4+ T cells from the spleens of 6-8-week-old BALB/c mice using magnetic bead sorting, which was used in our study for Treg differentiation. S1P stimulation was performed during Treg differentiation. We examined the oxygen consumption and palmitic acid metabolism of the differentiated Tregs and evaluated the expression levels of various proteins, including Nrf2, CPT1A, Glut1, ACC1 and PPARα, through Western blotting. Our results demonstrate that S1P promotes Treg differentiation and enhances FAO, and that the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and peroxisome proliferator-activated receptor α (PPARα) is upregulated. Furthermore, Nrf2 or PPARα knockdown dampened the Treg differentiation and FAO that were promoted by S1P, confirming that S1P can bind with S1PR4 to promote Treg differentiation through the Nrf2/PPARα signalling pathway, which may be related to FAO facilitation.

Sphingolipid-Based Synergistic Interactions to Enhance Chemosensitivity in Lung Cancer Cells

Tumor heterogeneity leads to drug resistance in cancer treatment with the crucial role of sphingolipids in cell fate and stress signaling. We analyzed sphingolipid metabolism and autophagic flux to study chemotherapeutic interactions on the A549 lung cancer model. Loaded cells with fluorescent sphingomyelin analog (BODIPY) and mCherry-EGFP-LC3B were used to track autophagic flux and assess cytotoxicity when cells are exposed to chemotherapy (epirubicin, cisplatin, and paclitaxel) together with sphingolipid pathway inhibitors and autophagy modulators. Our cell model approach employed fluorescent sphingolipid biosensors and a Gaussian Mixture Model of cell heterogeneity profiles to map the influence of chemotherapy on the sphingolipid pathway and infer potential synergistic interactions. Results showed significant synergy, especially when combining epirubicin with autophagy inducers (rapamycin and Torin), reducing cell viability. Cisplatin also synergized with a ceramidase inhibitor. However, paclitaxel often led to antagonistic effects. Our mapping model suggests that combining chemotherapies with autophagy inducers increases vesicle formation, possibly linked to ceramide accumulation, triggering cell death. However, the in silico model proposed ceramide accumulation in autophagosomes, and kinetic analysis provided evidence of sphingolipid colocalization in autophagosomes. Further research is needed to identify specific sphingolipids accumulating in autophagosomes. These findings offer insights into potential strategies for overcoming chemotherapy resistance by targeting the sphingolipid pathway.

Role of sphingosine 1-phosphate (S1P) in sepsis-associated intestinal injury

Sphingosine-1-phosphate (S1P) is a widespread lipid signaling molecule that binds to five sphingosine-1-phosphate receptors (S1PRs) to regulate downstream signaling pathways. Sepsis can cause intestinal injury and intestinal injury can aggravate sepsis. Thus, intestinal injury and sepsis are mutually interdependent. S1P is more abundant in intestinal tissues as compared to other tissues, exerts anti-inflammatory effects, promotes immune cell trafficking, and protects the intestinal barrier. Despite the clinical importance of S1P in inflammation, with a very well-defined mechanism in inflammatory bowel disease, their role in sepsis-induced intestinal injury has been relatively unexplored. In addition to regulating lymphocyte exit, the S1P-S1PR pathway has been implicated in the gut microbiota, intestinal epithelial cells (IECs), and immune cells in the lamina propria. This review mainly elaborates on the physiological role of S1P in sepsis, focusing on intestinal injury. We introduce the generation and metabolism of S1P, emphasize the maintenance of intestinal barrier homeostasis in sepsis, and the protective effect of S1P in the intestine. We also review the link between sepsis-induced intestinal injury and S1P-S1PRs signaling, as well as the underlying mechanisms of action. Finally, we discuss how S1PRs affect intestinal function and become targets for future drug development to improve the translational capacity of preclinical studies to the clinic.

Targeting sphingosine 1-phosphate receptor 3 inhibits T-cell exhaustion and regulates recruitment of proinflammatory macrophages to improve antitumor efficacy of CAR-T cells against solid tumor

BACKGROUNDS

Chimeric antigen receptor (CAR)-modified T cells (CAR-T) are limited in solid tumors due to the hostile tumor microenvironment (TME). Combination therapy could be a promising approach to overcome this obstacle. Recent studies have shown that sphingosine 1-phosphate receptor (S1PR)3 has tremendous potential in regulating the immune environment. However, the functional significance of S1PR3 in T-cell-based immunotherapies and the molecular mechanisms have not been fully understood.

METHODS

Here, we studied the combination of EpCAM-specific CAR T-cell therapy with pharmacological blockade of S1PR3 against solid tumor. We have applied RNA sequencing, flow cytometry, ELISA, cellular/molecular immunological technology, and mouse models of solid cancers.

RESULTS

Our study provided evidence that S1PR3 high expression is positively associated with resistance to programmed cell death protein-1 (PD-1)-based immunotherapy and increased T-cell exhaustion. In addition, pharmacological inhibition of S1PR3 improves the efficacy of anti-PD-1 therapy. Next, we explored the possible combination of S1PR3 antagonist with murine EpCAM-targeted CAR-T cells in immunocompetent mouse models of breast cancer and colon cancer. The results indicated that the S1PR3 antagonist could significantly enhance the efficacy of murine EpCAM CAR-T cells in vitro and in vivo. Mechanistically, the S1PR3 antagonist improved CAR-T cell activation, regulated the central memory phenotype, and reduced CAR-T cell exhaustion in vitro. Targeting S1PR3 was shown to remodel the TME through the recruitment of proinflammatory macrophages by promoting macrophage activation and proinflammatory phenotype polarization, resulting in improved CAR-T cell infiltration and amplified recruitment of CD8+T cells.

CONCLUSIONS

This work demonstrated targeting S1PR3 could increase the antitumor activities of CAR-T cell therapy at least partially by inhibiting T-cell exhaustion and remodeling the TME through the recruitment of proinflammatory macrophages. These findings provided additional rationale for combining S1PR3 inhibitor with CAR-T cells for the treatment of solid tumor.

Sphingolipid Metabolism in Tumor Cells

Sphingolipids are a diverse family of complex lipids typically composed of a sphingoid base bound to a fatty acid via amide bond. The metabolism of sphingolipids has long remained out of focus of biochemical studies. Recently, it has been attracting an increasing interest of researchers because of different and often multidirectional effects demonstrated by sphingolipids with a similar chemical structure. Sphingosine, ceramides (N-acylsphingosines), and their phosphorylated derivatives (sphingosine-1-phosphate and ceramide-1-phosphates) act as signaling molecules. Ceramides induce apoptosis and regulate stability of cell membranes and cell response to stress. Ceramides and sphingoid bases slow down anabolic and accelerate catabolic reactions, thus suppressing cell proliferation. On the contrary, their phosphorylated derivatives (ceramide-1-phosphate and sphingosine-1-phosphate) stimulate cell proliferation. Involvement of sphingolipids in the regulation of apoptosis and cell proliferation makes them critically important in tumor progression. Sphingolipid metabolism enzymes and sphingolipid receptors can be potential targets for antitumor therapy. This review describes the main pathways of sphingolipid metabolism in human cells, with special emphasis on the properties of this metabolism in tumor cells.

A novel co-target of ACY1 governing plasma membrane translocation of SphK1 contributes to inflammatory and neuropathic pain

Previous studies validate that inhibiting sodium channel 1.8 (Nav1.8) effectively relieves inflammatory and neuropathic pain. However, Nav1.8 blockers have cardiac side effects in addition to analgesic effects. Here, we constructed a spinal differential protein expression profile using Nav1.8 knockout mice to screen common downstream proteins of Nav1.8 in inflammatory and neuropathic pain. We found that aminoacylase 1 (ACY1) expression was increased in wild-type mice compared to Nav1.8 knockout mice in both pain models. Moreover, spinal ACY1 overexpression induced mechanical allodynia in naive mice, while ACY1 suppression alleviated inflammatory and neuropathic pain. Further, ACY1 could interact with sphingosine kinase 1 and promote its membrane translocation, resulting in sphingosine-1-phosphate upregulation and the activation of glutamatergic neurons and astrocytes. In conclusion, ACY1 acts as a common downstream effector protein of Nav1.8 in inflammatory and neuropathic pain and could be a new and precise therapeutic target for chronic pain.

Pretreatment with Bifidobacterium longum BAA2573 ameliorates dextran sulfate sodium (DSS)-induced colitis by modulating gut microbiota

Objectives

Inflammatory bowel disease (IBD) is a chronic lifelong inflammatory disease. Probiotics such as Bifidobacterium longum are considered to be beneficial to the recovery of intestinal inflammation by interaction with gut microbiota. Our goals were to define the effect of the exclusive use of BAA2573 on dextran sulfate sodium (DSS)-induced colitis, including improvement of symptoms, alleviation of histopathological damage, and modulation of gut microbiota.

Methods

In the present study, we pretreated C57BL/6J mice with Bifidobacterium longum BAA2573, one of the main components in an over-the-counter (OTC) probiotic mixture BIFOTO capsule, before modeling with DSS. 16S rDNA sequencing and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based non-targeted metabolomic profiling were performed with the collected feces.

Results

We found that pretreatment of Bifidobacterium longum BAA2573 given by gavage significantly improved symptoms and histopathological damage in DSS-induced colitis mice. After the BAA2573 intervention, 57 genera and 39 metabolites were significantly altered. Pathway enrichment analysis demonstrated that starch and sucrose metabolism, vitamin B6 metabolism, and sphingolipid metabolism may contribute to ameliorating colitis. Moreover, we revealed that the gut microbiome and metabolites were interrelated in the BAA2573 intervention group, while Alistipes was the core genus.

Conclusion

Our study demonstrates the impact of BAA2573 on the gut microbiota and reveals a possible novel adjuvant therapy for IBD patients.

Current advancements and future perspectives of long noncoding RNAs in lipid metabolism and signaling

BACKGROUND

The investigation of lncRNAs has provided a novel perspective for elucidating mechanisms underlying diverse physiological and pathological processes. Compelling evidence has revealed an intrinsic link between lncRNAs and lipid metabolism, demonstrating that lncRNAs-induced disruption of lipid metabolism and signaling contribute to the development of multiple cancers and some other diseases, including obesity, fatty liver disease, and cardiovascular disease.

AIMOF REVIEW

The current review summarizes the recent advances in basic research about lipid metabolism and lipid signaling-related lncRNAs. Meanwhile, the potential and challenges of targeting lncRNA for the therapy of cancers and other lipid metabolism-related diseases are also discussed.

KEY SCIENTIFIC CONCEPT OF REVIEW

Compared with the substantial number of lncRNA loci, we still know little about the role of lncRNAs in metabolism. A more comprehensive understanding of the function and mechanism of lncRNAs may provide a new standpoint for the study of lipid metabolism and signaling. Developing lncRNA-based therapeutic approaches is an effective strategy for lipid metabolism-related diseases.

Recent advances in the treatment of IBD: Targets, mechanisms and related therapies

Inflammatory bowel disease (IBD), as a representative inflammatory disease, currently has multiple effective treatment options available and new therapeutic strategies are being actively explored to further increase the treatment options for patients with IBD. Furthermore, biologic agents and small molecule drugs developed for ulcerative colitis (UC) and Crohn's disease (CD) have evolved toward fewer side effects and more accurate targeting. Novel inhibitors that target cytokines (such as IL-12/23 inhibitors, PDE4 inhibitors), integrins (such as integrin inhibitors), cytokine signaling pathways (such as JAK inhibitors, SMAD7 blocker) and cell signaling receptors (such as S1P receptor modulator) have become the preferred treatment choice for many IBD patients. Conventional therapies such as 5-aminosalicylic acid, corticosteroids, immunomodulators and anti-tumor necrosis factor agents continue to demonstrate therapeutic efficacy, particularly in combination with drug therapy. This review integrates research from chemical, biological and adjuvant therapies to evaluate current and future IBD therapies, highlighting the mechanism of action of each therapy and emphasizing the potential of development prospects.

Polyamine metabolism patterns characterized tumor microenvironment, prognosis, and response to immunotherapy in colorectal cancer

BACKGROUND

Changes in Polyamine metabolism (PAM) have been shown to establish a suppressive tumor microenvironment (TME) and substantially influence the progression of cancer in the recent studies. However, newly emerging data have still been unable to fully illuminate the specific effects of PAM in human cancers. Here, we analyzed the expression profiles and clinical relevance of PAM genes in colorectal cancer (CRC).

METHODS

Based on unsupervised consensus clustering and principal component analysis (PCA) algorithm, we designed a scoring model to evaluate the prognosis of CRC patients and characterize the TME immune profiles, with related independent immunohistochemical validation cohort. Through comparative profiling of cell communities defined by single cell sequencing data, we identified the distinct characteristics of polyamine metabolism in the TME of CRC.

RESULTS

Three PAM patterns with distinct prognosis and TME features were recognized from 1224 CRC samples. Moreover, CRC patients could be divided into high- and low-PAMscore subgroups by PCA-based scoring system. High PAMscore subgroup were associated to more advanced stage, higher infiltration level of immunosuppressive cells, and unfavorable prognosis. These results were also validated in CRC samples from other public CRC datasets and our own cohort, which suggested PAM genes were ideal biomarkers for predicting CRC prognosis. Notably, PAMscore also corelated with microsatellite instability-high (MSI-H) status, higher tumor mutational burden (TMB), and increased immune checkpoint gene expression, implying a potential role of PAM genes in regulating response to immunotherapy. To further confirm above results, we demonstrated a high-resolution landscape of TME and cell-cell communication network in different PAM patterns using single cell sequencing data and found that polyamine metabolism affected the communication between cancer cells and several immune cells such as T cells, B cells and myeloid cells.

CONCLUSION

In total, our findings highlighted the significance of polyamine metabolism in shaping the TME and predicting the prognosis of CRC patients, providing novel strategies for immunotherapy and the targeting polyamine metabolites.

Prognosis-related metabolic genes in the development of colorectal cancer progress and perspective

Colorectal cancer (CRC) is one of the most commonplace malignant tumors in the world. The occurrence and development of CRC are involved in numerous events. Metabolic reprogramming is one of the hallmarks of cancer and is convoluted and associated with carcinogenesis. Lots of metabolic genes are involved in the occurrence and progression of CRC. Study methods combining tumor genomics and metabolomics are more likely to explore this field in depth. In this mini-review, we make the latest progress and future prospects into the different molecular mechanisms of seven prognosis-related metabolic genes, we screened out in previous research, involved in the occurrence and development of CRC.

Sphingosine-1-Phosphate Recruits Macrophages and Microglia and Induces a Pro-Tumorigenic Phenotype That Favors Glioma Progression

Glioblastoma is the most aggressive brain tumor in adults. Treatment failure is predominantly caused by its high invasiveness and its ability to induce a supportive microenvironment. As part of this, a major role for tumor-associated macrophages/microglia (TAMs) in glioblastoma development was recognized. Phospholipids are important players in various fundamental biological processes, including tumor-stroma crosstalk, and the bioactive lipid sphingosine-1-phosphate (S1P) has been linked to glioblastoma cell proliferation, invasion, and survival. Despite the urgent need for better therapeutic approaches, novel strategies targeting sphingolipids in glioblastoma are still poorly explored. Here, we showed that higher amounts of S1P secreted by glioma cells are responsible for an active recruitment of TAMs, mediated by S1P receptor (S1PR) signaling through the modulation of Rac1/RhoA. This resulted in increased infiltration of TAMs in the tumor, which, in turn, triggered their pro-tumorigenic phenotype through the inhibition of NFkB-mediated inflammation. Gene set enrichment analyses showed that such an anti-inflammatory microenvironment correlated with shorter survival of glioblastoma patients. Inhibition of S1P restored a pro-inflammatory phenotype in TAMs and resulted in increased survival of tumor-bearing mice. Taken together, our results establish a crucial role for S1P in fine-tuning the crosstalk between glioma and infiltrating TAMs, thus pointing to the S1P-S1PR axis as an attractive target for glioma treatment.

Unveiling the biological role of sphingosine-1-phosphate receptor modulators in inflammatory bowel diseases

Inflammatory bowel disease (IBD) is chronic inflammation of the gastrointestinal tract that has a high epidemiological prevalence worldwide. The increasing disease burden worldwide, lack of response to current biologic therapeutics, and treatment-related immunogenicity have led to major concerns regarding the clinical management of IBD patients and treatment efficacy. Understanding disease pathogenesis and disease-related molecular mechanisms is the most important goal in developing new and effective therapeutics. Sphingosine-1-phosphate (S1P) receptor (S1PR) modulators form a class of oral small molecule drugs currently in clinical development for IBD have shown promising effects on disease improvement. S1P is a sphingosine-derived phospholipid that acts by binding to its receptor S1PR and is involved in the regulation of several biological processes including cell survival, differentiation, migration, proliferation, immune response, and lymphocyte trafficking. T lymphocytes play an important role in regulating inflammatory responses. In inflamed IBD tissue, an imbalance between T helper (Th) and regulatory T lymphocytes and Th cytokine levels was found. The S1P/S1PR signaling axis and metabolism have been linked to inflammatory responses in IBD. S1P modulators targeting S1PRs and S1P metabolism have been developed and shown to regulate inflammatory responses by affecting lymphocyte trafficking, lymphocyte number, lymphocyte activity, cytokine production, and contributing to gut barrier function.

S1PR1/S1PR3-YAP signaling and S1P-ALOX15 signaling contribute to an aggressive behavior in obesity-lymphoma

BACKGROUND

Excess body weight has been found to associate with an increased risk of lymphomas and some metabolic pathways are currently recognized in lymphomagenesis. Bioactive lipid metabolites such as sphingosine-1-phosphate (S1P) have been proposed to play an important role linking obesity and lymphomas. However, the underlying mechanism(s) of S1P signaling in obesity-lymphomagenesis have not been well addressed.

METHODS

The gene expression of sphingosine kinase (SPHK), lymphoma prognosis, and S1P production were analyzed using Gene Expression Omnibus (GEO) and human lymphoma tissue array. Obesity-lymphoma mouse models and lymphoma cell lines were used to investigate the S1P/SPHK-YAP axis contributing to obesity-lymphomagenesis. By using the mouse models and a monocyte cell line, S1P-mediated polarization of macrophages in the tumor microenvironment were investigated.

RESULTS

In human study, up-regulated S1P/SPHK1 was found in human lymphomas, while obesity negatively impacted progression-free survival and overall survival in lymphoma patients. In animal study, obesity-lymphoma mice showed an aggressive tumor growth pattern. Both in vivo and in vitro data suggested the existence of S1P-YAP axis in lymphoma cells, while the S1P-ALOX15 signaling mediated macrophage polarization towards TAMs exacerbated the lymphomagenesis. In addition, treatment with resveratrol in obesity-lymphoma mice showed profound effects of anti-lymphomagenesis, via down-regulating S1P-YAP axis and modulating polarization of macrophages.

CONCLUSION

S1P/S1PR initiated the feedback loops, whereby S1P-S1PR1/S1PR3-YAP signaling mediated lymphomagenesis contributing to tumor aggressive growth, while S1P-ALOX15 signaling mediated TAMs contributing to immunosuppressive microenvironment in obesity-lymphoma. S1P-targeted therapy could be potentially effective and immune-enhancive against obesity-lymphomagenesis.

Dexmedetomidine (Dex) exerts protective effects on rat neuronal cells injured by cerebral ischemia/reperfusion via regulating the Sphk1/S1P signaling pathway

AIM

To investigate the influence of dexmedetomidine (Dex) on cerebral ischemia/reperfusion (I/R)-injured rat neuronal cells by regulating the Sphk1/S1P pathway.

METHODS

The rats were divided into the following groups, with 18 rats in each group categorized on the basis of random number tables: sham (Sham), I/R (I/R), Dex, Sphk1 inhibitor (PF-543), and Dex together with the Sphk1 agonist phorbol-12-myristate-13-acetate (Dex+PMA). The neurological functions of the rats were assessed by the Longa scoring system at 24 h post reperfusion. The area of brain infarction was inspected using 2,3,5-triphenyltetrazolium chloride staining, and the water content of brain tissue was determined by the dry-wet weight method. The morphology of neurons in the CA1 region of the rat hippocampus was inspected using Nissl staining, while the apoptosis of neurons in this region was detected by terminal-deoxynucleotidyl transferase mediated nick end labeling staining. The Sphk1 and S1P protein levels were determined by immunofluorescence and western blotting, respectively.

RESULTS

Compared to the I/R group, rats in the Dex, PF-543, and Dex+PMA groups had a significantly lower neurological function score, as well as lower brain water content and a decreased infarction area. Moreover, the apoptotic index of the neurons and the Sphk1 and S1P levels in the hippocampal CA1 region were significantly lower in these groups (p<0.05). PMA, an agonist of Sphk1, was able to reverse the protective effects of Dex on I/R-induced neuronal cell injury.

CONCLUSION

Dex could protect cerebral I/R-induced neuronal cell injury by suppressing the Sphk1/S1P signaling pathway.

Integrating HPLC-Q-TOF-MS/MS, network pharmacology and experimental validation to decipher the chemical substances and mechanism of modified Gui-shao-liu-jun-zi decoction against gastric cancer

Background and aim

Gastric cancer (GC) is a common malignant tumor worldwide. Modified Gui-shao-liu-jun-zi decoction (mGSLJZ) is a clinically effective traditional Chinese medicine (TCM) compound in GC treatment. This study aimed to analyze main chemical substances of mGSLJZ and investigate active ingredients and molecular mechanism of mGSLJZ against GC.

Experimental procedure

HPLC-Q-TOF-MS/MS was used to analyze chemical substances of mGSLJZ, and potential active ingredients were screened from TCMSP. The target set of mGSLJZ for GC was obtained based on SwissTargetPrediction. The PPI network was constructed to screen out core targets. GO and KEGG enrichment analyses were conducted to identify BPs, CCs, MFs and pathways. The "active ingredient-core target-pathway" regulatory network was constructed to obtain core substances. Subsequently, Oncomine, Proteinatlas and molecular docking were performed to validate these findings. The cell experiments were conducted to confirm the anti-GC effects of mGLSJZ.

Results and conclusion

Forty-one potential active ingredients were filtered out from 120 chemical substances in mGSLJZ, including various organic acids and flavonoids. The top 10 key targets, 20 related pathways and 6 core medicinal substances were obtained based on network pharmacology analysis. Molecular docking results indicated that the core substances and key targets had good binding activities. The cell experiments validated that mGSLJZ and the core substances inhibited the proliferation in multiple GC cells and that mGLSJZ restrained the migration of GC. Meanwhile, the top 5 targets and top 2 pathways were verified. The rescue experiments demonstrated that mGSLJZ suppressed the proliferation and migration of GC through the PI3K/AKT/HIF-1 pathway.

Identification of Critical Modules and Biomarkers of Ulcerative Colitis by Using WGCNA

Background

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon and rectum that has no exact cause and is characterized by relapsing and remitting episodes. We aimed to find biomarkers of UC and its causes.

Methods

We got GSE73661 from the GEO database and used WGCNA to find DEGs that were expressed in the same way in both normal and UC samples. To identify the co-expression modules, we used Weighted Gene Co-Expression Network Analysis. Next, we selected genes that were both DEGs and parts of main modules. Later, three datasets were used to find the hub genes, and qRT-PCR was utilized to confirm the in-silico findings. Additionally, we analyzed the connection between the hub genes and the filtration of immune cells in UC. Using the databases, we made predictions about the miRNAs and lncRNAs that regulate the hub genes and predicted possible therapeutic drugs.

Results

We found 822 DEGs and three main modules related to immunity, endoplasmic reticulum, and metabolism. Using another three datasets and human samples to confirm the mRNA expression of these genes in UC patients, XBP1 and PLPP1 were selected as hub genes, and had excellent diagnostic potential. According to the findings of the immune infiltration, patients with UC exhibited a larger proportion of immune cells. And hub genes, particularly XBP1, were closely linked to a number of immune cell infiltrations. Based on the databases and hub genes, a lncRNA-miRNA-mRNA network, including two miRNAs (miR-214-3p and miR-93-5p), two hub genes, and 124 lncRNAs, and potential therapeutic medicine were identified.

Conclusion

We found two new genes, XBP1 and PLPP1, that are involved in UC and can help diagnose and measure the disease. XBP1 also relates to clinical scores and immune cells. We suggested a gene network and possible drugs based on them.

Targeting SPHK1/S1PR3-regulated S-1-P metabolic disorder triggers autophagic cell death in pulmonary lymphangiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM), a progressive pulmonary disease exclusively affecting females, is caused by defects or mutations in the coding gene tuberous sclerosis complex 1 (TSC1) or TSC2, causing the mammalian target of rapamycin complex 1 (mTORC1) activation and autophagy inhibition. Clinically, rapamycin shows limited cytocidal effects, and LAM recurs after drug withdrawal. In this study, we demonstrated that TSC2 negatively regulated the sphingolipid metabolism pathway and the expressions of sphingosine kinase 1 (SPHK1) and sphingosine-1-phosphate receptor 3 (S1PR3) were significantly elevated in LAM patient-derived TSC2-deficient cells compared to TSC2-addback cells, insensitive to rapamycin treatment and estrogen stimulation. Knockdown of SPHK1 showed reduced viability, migration and invasion in TSC2-deficient cells. Selective SPHK1 antagonist PF543 potently suppressed the viability of TSC2-deficient cells and induced autophagy-mediated cell death. Meanwhile, the cognate receptor S1PR3 was identified to mediating the tumorigenic effects of sphingosine-1-phosphate (S1P). Treatment with TY52156, a selective antagonist for S1PR3, or genetic silencing using S1PR3-siRNA suppressed the viability of TSC2-deficient cells. Both SPHK1 and S1PR3 inhibitors markedly exhibited antitumor effect in a xenograft model of TSC2-null cells, restored autophagy level, and triggered cell death. Together, we identified novel rapamycin-insensitive sphingosine metabolic signatures in TSC2-null LAM cells. Therapeutic targeting of aberrant SPHK1/S1P/S1PR3 signaling may have potent therapeutic benefit for patients with TSC/LAM or other hyperactive mTOR neoplasms with autophagy inhibition.

Expression Profile of Sphingosine Kinase 1 Isoforms in Human Cancer Tissues and Cells: Importance and Clinical Relevance of the Neglected 1b-Isoform

Background

Overexpression of sphingosine kinase 1 (SphK1) is casually associated with many types of cancer, and inhibitors of SphK1 sensitize tumors to chemotherapy. SphK1 is expressed as two major isoforms, SphK1a and SphK1b. To date, no information has been reported on the SphK1 isoform expression profile and its clinical relevance.

Objective

The objective is to examine the expression profile of the SphK1a and SPhK1b isoforms in human cancer and noncancer tissues and cell lines and explore their clinical relevance.

Methods

We used PCR to qualitatively examine the expression profile of these two isoforms in breast, liver, and prostate cancer tissues plus paired adjacent tissues and in 11 cancer and normal cell lines (breast, cervical, bone, prostate, colon, brain, mesothelioma tumor and benign, and human kidney cells).

Results

We found that SphK1a was ubiquitously expressed in all cancer cells and tissues tested; in contrast, SphK1b was only expressed in selective cell types in breast, prostate, and lung cancer.

Conclusions

Our data suggest that SphK1a is important for generic SphK1/S1P functions, and SphK1b mediates specialized and/or unique pathways in a specific type of tissue and could be a biomarker for cancer. This discovery is important for future SphK1-related cancer research and may have clinical implications in drug development associated with SphK1-directed cancer treatment.

Dietary Inflammatory Nutrients and Esophageal Squamous Cell Carcinoma Risk: A Case-Control Study

We conducted a case-control study (532 cases and 532 control) in Chinese adults to investigate the independent and interactive effects of dietary nutrients (pro- or anti-inflammation) on Esophageal Squamous Cell Carcinoma (ESCC) risk. Dietary data were collected using a food questionnaire survey that included 171 items. Two algorithms, the Least Absolute Shrinkage and Selector Operation (LASSO) and Bayesian Kernel Machine Regression (BKMR) were employed to select indicators and evaluate the interactive effect of nutrients' mixture on ESCC risk. Thirteen nutrients were selected, including three pro-inflammatory nutrients (protein, fat and carbohydrate) and ten anti-inflammatory nutrients (fiber, Vitamin A, riboflavin, niacin, Vitamin C, Fe, Se, MUFA, n-3 PUFA and n-6 PUFA). Single-exposure effects of fat, carbohydrate and fiber significantly contributed to ESCC risk. The pro-inflammatory nutrients' submodel discovered that the combined effect was statistically associated with increased ESCC risk. In addition, a higher fat level was significantly associated with ESCC risk. On the contrary, for fiber and riboflavin, the anti-inflammatory nutrients' submodel delineated a significant negative effect on the risk of ESCC. Our result implies that dietary nutrients and their inflammatory traits significantly impacted ESCC occurrence. Additional studies are warranted to verify our findings.

Triptolide Inhibits the Biological Processes of HUVECs and HepG2 Cells via the Serine Palmitoyltransferase Long Chain Base Subunit 2/Sphingosine-1-Phosphate Signaling Pathway

Triptolide (TP) has demonstrated innumerous biological effects and pharmacological potential against different cancer types. Hepatocellular carcinoma has a high incidence in men, and its incidence is increasing year by year. Studies have shown that angiogenesis plays an important role in the formation of tumors and that angiogenesis is closely related to tumor growth and metastasis. Deregulation of sphingolipids signaling has been associated with several pathological conditions, including cancer. In the present study, we aimed at exploring the potential molecular mechanism of TP's antivascular and antitumor effects in vitro from the perspective of sphinolipids. Human umbilical vein endothelial cells (HUVECs) and HepG2 cells were, respectively, treated with different concentrations of TP and transfected. Then, the effect of HUVECs on HepG2 cells was investigated using a three-dimensional coculture model system. CCK-8 assay was performed for cell proliferation. Cell migration and invasion abilities were assessed using the transwell assay. Cell adhesion and tube formation were detected by Matrigel. RT-PCR and western blotting were used to detect the mRNA and protein expression. The S1P production was measured via ELISA assay. Our results showed that TP inhibited HUVECs and HepG2 cells proliferation, migration, invasion, adhesion, angiogenesis, and serine palmitoyltransferase long chain base subunit 2 (SPTLC2) expression; upregulating SPTLC2 facilitated the proliferation, migration, invasion, adhesion, angiogenesis, and sphingosine-1-phosphate (S1P) production of HUVECs and HepG2 cells, while interfering with SPTLC2 expression inhibited them; HUVECs facilitated the proliferation, migration, invasion, S1P production, S1PR1, and S1PR2 expression of HepG2 cells, while S1PR3 expression was decreased. In conclusion, SPTLC2 may be associated with the antivascular and antitumor effects of TP, and SPTLC2 is expected to become a new marker for tumor therapy. HUVECs can promote the proliferation, migration, and invasion of HepG2 cells, which may be related to the S1P/sphingosine-1-phosphate receptor (S1PR) signaling pathway.

The Sphingosine Kinase 2 Inhibitor Opaganib Protects Against Acute Kidney Injury in Mice

Introduction

Acute kidney injury (AKI) is a common multifactorial adverse effect of surgery, circulatory obstruction, sepsis or drug/toxin exposure that often results in morbidity and mortality. Sphingolipid metabolism is a critical regulator of cell survival and pathologic inflammation processes involved in AKI. Opaganib (also known as ABC294640) is a first-in-class experimental drug targeting sphingolipid metabolism that reduces the production and activity of inflammatory cytokines and, therefore, may be effective to prevent and treat AKI.

Methods

Murine models of AKI were used to assess the in vivo efficacy of opaganib including ischemia-reperfusion (IR) injury induced by either transient bilateral occlusion of renal blood flow (a moderate model) or nephrectomy followed immediately by occlusion of the contralateral kidney (a severe model) and lipopolysaccharide (LPS)-induced sepsis. Biochemical and histologic assays were used to quantify the effects of oral opaganib treatment on renal damage in these models.

Results

Opaganib suppressed the elevations of creatinine and blood urea nitrogen (BUN), as well as granulocyte infiltration into the kidneys, of mice that experienced moderate IR from transient bilateral ligation. Opaganib also markedly decreased these parameters and completely prevented mortality in the severe renal IR model. Additionally, opaganib blunted the elevations of BUN, creatinine and inflammatory cytokines following exposure to LPS.

Conclusion

The data support the hypotheses that sphingolipid metabolism is a key mediator of renal inflammatory damage following IR injury and sepsis, and that this can be suppressed by opaganib. Because opaganib has already undergone clinical testing in other diseases (cancer and Covid-19), the present studies support conducting clinical trials with this drug with surgical or septic patients at risk for AKI.

Sphingosine kinase 1 promotes tumor immune evasion by regulating the MTA3-PD-L1 axis

Immune checkpoint blockade (ICB) exhibits considerable benefits in malignancies, but its overall response rate is limited. Previous studies have shown that sphingosine kinases (SPHKs) are critical in the tumor microenvironment (TME), but their role in immunotherapy is unclear. We performed integrative analyses including bioinformatics analysis, functional study, and clinical validation to investigate the role of SPHK1 in tumor immunity. Functionally, we demonstrated that the inhibition of SPHK1 significantly suppressed tumor growth by promoting antitumor immunity in immunocompetent melanoma mouse models and tumor T-cell cocultures. A mechanistic analysis revealed that MTA3 functions as the downstream target of SPHK1 in transcriptionally regulating tumor PD-L1. Preclinically, we found that anti-PD-1 monoclonal antibody (mAb) treatment significantly rescued tumor SPHK1 overexpression or tumor MTA3 overexpression-mediated immune evasion. Significantly, we identified SPHK1 and MTA3 as biological markers for predicting the efficacy of anti-PD-1 mAb therapy in melanoma patients. Our findings revealed a novel role for SPHK1 in tumor evasion mediated by regulating the MTA3-PD-L1 axis, identified SPHK1 and MTA3 as predictors for assessing the efficacy of PD-1 mAb treatment, and provided a therapeutic possibility for the treatment of melanoma patients.

Metabolomic transition trajectory and potential mechanisms of N-nitrosomethylbenzylamine induced esophageal squamous cell carcinoma in rats

Esophageal squamous cell carcinoma (ESCC) is an environment-relevant malignancy with a high mortality. Nitrosamines, a class of nitrogen-containing environmental carcinogens, are widely suggested as a risk factor for ESCC. However, how nitrosamines affect metabolic regulation to promote ESCC tumorigenesis is largely unknown. In this study, the transition trajectory of serum metabolism in the course of ESCC induced by N-nitrosomethylbenzylamine (NMBA) in rats was depicted by an untargeted metabolomic analysis, and the potential molecular mechanisms were revealed. The results showed that the metabolic alteration in rats was slight at the basal cell hyperplasia (BCH) stage, while it became apparent when the esophageal lesion developed into dysplasia (DYS) or more serious conditions. Moreover, serum metabolism of severe dysplasia (S-DYS) showed more similar characteristics to that of carcinoma in situ (CIS) and invasive cancer (IC). Aberrant nicotinate (NA) and nicotinamide (NAM) metabolism, tryptophan (TRP) metabolism, and sphingolipid metabolism could be the key players favoring the malignant transformation of esophageal epithelium induced by NMBA. More particularly, NA and NAM metabolism in the precancerous stages and TRP metabolism in the cancerous stages were demonstrated to replenish NAD⁺ in different patterns. Furthermore, both the IDO1-KYN-AHR axis mediated by TRP metabolism and the SPHK1-S1P-S1PR1 axis by sphingolipid metabolism provided an impetus to create the pro-inflammatory yet immune-suppressive microenvironment to facilitate the esophageal tumorigenesis and progression. Together, these suggested that NMBA exerted its carcinogenicity via more than one pathway, which may act together to produce combination effects. Targeting these pathways may open up the possibility to attenuate NMBA-induced esophageal carcinogenesis. However, the interconnection between different metabolic pathways needs to be specified further. And the integrative and multi-level systematic research will be conducive to fully understanding the mechanisms of NMBA-induced ESCC.

Inhibition of Sphingosine Kinase Activity Enhances Immunogenic Cell Surface Exposure of Calreticulin Induced by the Synthetic Cannabinoid 5-epi-CP-55,940

Background: Endogenous and synthetic cannabinoids have been shown to induce cancer cell death through the accumulation of the sphingolipid, ceramide (Cer). Recently, we have demonstrated that Cer accumulation enhances the induction of immunogenic cell death (ICD). Objectives: The primary objective of this study was to demonstrate that (±) 5-epi CP 55,940 (5-epi), a by-product of the chemical synthesis of the synthetic cannabinoid CP 55,940, induces ICD in colorectal cancer (CRC) cells, and that modulation of the sphingolipid metabolic pathway through inhibition of the sphingosine kinases (SphKs) enhances these effects. Methods: A cell culture model system of human CRC cell lines was employed to measure the cell surface and intracellular production of markers of ICD. The effects of 5-epi, alone and in combination with SphK inhibitors, on production of Cer through the de novo sphingolipid synthesis pathway were measured by Liquid Chromatography - Tandem Mass Spectrometry (LC/MS/MS)-based sphingolipidomic analysis. Cell surface exposure of calreticulin (ectoCRT), a hallmark of ICD, was measured by flow cytometry. Examination of the effects of 5-epi, alone and in combination with SphK inhibitors, on the intracellular signaling pathway associated with ICD was conducted by immunoblot analysis of human CRC cell lines. Results: Sphingolipidomic analysis indicated that 5-epi induces the de novo sphingolipid synthetic pathway. 5-epi dose dependently induces cell surface exposure of ectoCRT, and inhibition of Cer metabolism through inhibition of the SphKs significantly enhances 5-epi-induced ectoCRT exposure in multiple CRC cell lines. 5-epi induces and SphK inhibition enhances activation of the cell death signaling pathway associated with ICD. Conclusions: This study is the first demonstration that cannabinoids can induce the cell surface expression of ectoCRT, and potentially induce ICD. Moreover, this study reinforces our previous observation of a role for Cer accumulation in the induction of ICD and extends this observation to the cannabinoids, agents not typically associated with ICD. Inhibition of SphKs enhanced the 5-epi-induced signaling pathways leading to ICD and production of ectoCRT. Overexpression of SphK1 has previously been associated with chemotherapy resistance. Thus, targeting the SphKs has the potential to reverse chemotherapy resistance and simultaneously enhance the antitumor immune response through enhancement of ICD induction.