The emerging role of FTY720 (Fingolimod) in cancer treatment

PLGA nanomedical consignation: A novel approach for the management of prostate cancer

The malignancy of the prostate is a complicated ailment which impacts millions of male populations around the globe. Despite the multitude of endeavour accomplished within this domain, modalities that are involved in the ameliorative management of predisposed infirmity are still relent upon non-specific and invasive procedures, thus imposing a detrimental mark on the living standard of the individual. Also, the orchestrated therapeutic interventions are still incompetent in substantiating a robust and unabridged therapeutic end point owing to their inadequate solubility, low bioavailability, limited cell assimilation, and swift deterioration, thereby muffling the clinical application of these existing treatment modalities. Nanotechnology has been employed in an array of modalities for the medical management of malignancies. Among the assortment of available nano-scaffolds, nanocarriers composed of a bio-decomposable and hybrid polymeric material like PLGA hold an opportunity to advance as standard chemotherapeutic modalities. PLGA-based nanocarriers have the prospect to address the drawbacks associated with conventional cancer interventions, owing to their versatility, durability, nontoxic nature, and their ability to facilitate prolonged drug release. This review intends to describe the plethora of evidence-based studies performed to validate the applicability of PLGA nanosystem in the amelioration of prostate malignancies, in conjunction with PLGA focused nano-scaffold in the clinical management of prostate carcinoma. This review seeks to explore numerous evidence-based studies confirming the applicability of PLGA nanosystems in ameliorating prostate malignancies. It also delves into the role of PLGA-focused nano-scaffolds in the clinical management of prostate carcinoma, aiming to provide a comprehensive perspective on these advancements.

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.

Therapeutic Potential of Fingolimod in Diabetes Mellitus and Its Chronic Complications

Diabetes mellitus is a metabolic disease characterized by elevated blood glucose due to a deficiency of insulin secretion and/or action. Long-term poor blood glucose control may lead to chronic damage and dysfunction of the heart, kidneys, eyes, and other organs. Therefore, it is important to develop treatments for diabetes and its chronic complications. Fingolimod is a structural sphingosine analogue and sphingosine-1-phosphate receptor modulator currently used for the treatment of relapsing-remitting multiple sclerosis. Several studies have shown that it has beneficial effects on the improvement of diabetes and its chronic complications. This paper reviews the therapeutic potential of Fingolimod in diabetes and its chronic complications, aiming to further guide future treatment strategies.

SPHK1/S1P/S1PR pathway promotes the progression of peritoneal fibrosis by mesothelial-mesenchymal transition

Long-term exposure to non-physiologically compatible dialysate inevitably leads to peritoneal fibrosis (PF) in patients undergoing peritoneal dialysis (PD), and there is no effective prevention or treatment for PF. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid produced after catalysis by sphingosine kinase (SPHK) 1/2 and activates signals through the S1P receptor (S1PR) via autocrine or paracrine. However, the role of SPHK1/S1P/S1PR signaling has never been elucidated in PF. In our research, we investigated S1P levels in peritoneal effluents and demonstrated the role of SPHK1/S1P/S1PR pathway in peritoneal fibrosis. It was found that S1P levels in peritoneal effluents were positively correlated with D/P Cr (r = 0.724, p < .001) and negatively correlated with 4 h ultrafiltration volume (r = -0.457, p < .001). S1PR1 and S1PR3 on peritoneal cells were increased after high glucose exposure in vivo and in vitro. Fingolimod was applied to suppress S1P/S1PR pathway. Fingolimod restored mouse peritoneal function by reducing interstitial hyperplasia, maintaining ultrafiltration volume, reducing peritoneal transport solute rate, and mitigating the protein expression changes of fibronectin, vimentin, α-SMA, and E-cadherin induced by PD and S1P. Fingolimod preserved the morphology of the human peritoneal mesothelial cells, MeT-5A, and moderated the mesothelial-mesenchymal transition (MMT) process. We further delineated that SPHK1 was elevated in peritoneal cells after high glucose exposure and suppression of SPHK1 in MeT-5A cells reduced S1P release. Overexpression of SPHK1 in MeT-5A cells increased S1P levels in the supernatant and fostered the MMT process. PF-543 treatment, targeting SPHK1, alleviated deterioration of mouse peritoneal function. In conclusion, S1P levels in peritoneal effluent were correlated with the deterioration of peritoneal function. SPHK1/S1P/S1PR pathway played an important role in PF.

The sphingosine-1-phosphate receptor 1 modulator ponesimod repairs cuprizone-induced demyelination and induces oligodendrocyte differentiation

Sphingosine-1-phosphate receptor (S1PR) modulators are clinically used to treat relapse-remitting multiple sclerosis (MS) and the early phase of progressive MS when inflammation still prevails. In the periphery, S1PR modulators prevent lymphocyte egress from lymph nodes, hence hampering neuroinflammation. Recent findings suggest a role for S1PR modulation in remyelination. As the Giα-coupled S1P1 subtype is the most prominently expressed S1PR in oligodendrocyte precursor cells (OPCs), selective modulation (functional antagonism) of S1P1 may have direct effects on OPC functionality. We hypothesized that functional antagonism of S1P1 by ponesimod induces remyelination by boosting OPC differentiation. In the cuprizone mouse model of demyelination, we found ponesimod to decrease the latency time of visual evoked potentials compared to vehicle conditions, which is indicative of functional remyelination. In addition, the Y maze spontaneous alternations test revealed that ponesimod reversed cuprizone-induced working memory deficits. Myelin basic protein (MBP) immunohistochemistry and transmission electron microscopy of the corpus callosum revealed an increase in myelination upon ponesimod treatment. Moreover, treatment with ponesimod alone or in combination with A971432, an S1P5 monoselective modulator, significantly increased primary mouse OPC differentiation based on O4 immunocytochemistry. In conclusion, S1P1 functional antagonism by ponesimod increases remyelination in the cuprizone model of demyelination and significantly increases OPC differentiation in vitro.

Mysterious sphingolipids: metabolic interrelationships at the center of pathophysiology

Metabolic pathways are complex and intertwined. Deficiencies in one or more enzymes in a given pathway are directly linked with genetic diseases, most of them having devastating manifestations. The metabolic pathways undertaken by sphingolipids are diverse and elaborate with ceramide species serving as the hubs of sphingolipid intermediary metabolism and function. Sphingolipids are bioactive lipids that serve a multitude of cellular functions. Being pleiotropic in function, deficiency or overproduction of certain sphingolipids is associated with many genetic and chronic diseases. In this up-to-date review article, we strive to gather recent scientific evidence about sphingolipid metabolism, its enzymes, and regulation. We shed light on the importance of sphingolipid metabolism in a variety of genetic diseases and in nervous and immune system ailments. This is a comprehensive review of the state of the field of sphingolipid biochemistry.

Risk of cancer with immunosuppressants compared to immunomodulators in multiple sclerosis: A nested case-control study within the French nationwide claims database

PURPOSE

The objective was to compare the risk of malignancies in real-world settings between exclusive immunosuppressant (IS) and immunomodulator (IM) use in multiple sclerosis (MS).

METHODS

A nested case-control study was designed within a new-user cohort of all patients with MS who initiated a first IM or IS between 2008 and 2014, and without cancer history, using the information of the SNDS nationwide French claims database. Incident cancer cases were matched with up to six controls on year of birth, sex, initiation date, and disease risk score of cancer. A conditional logistic regression (odds ratio [95% confidence interval]) was used to compare exclusive IS versus IM use during follow-up and according to three use durations.

RESULTS

From 28 720 newly treated patients with MS, 407 incident cancers were observed during the follow-up with 2324 matched controls. A significant increase in cancer risk was observed for IS compared with IM (1.36 [1.05, 1.77]), with similar increases for the first 2 years of use but not for ≥2 years (1.06 [0.65, 1.75]). Similar increase was also observed for IS with indications other than MS (1.37 [1.04, 1.81]) but not for IS indicated only in MS (1.03 [0.45, 2.34]).

CONCLUSIONS

Compared with IM, a 37% increase in cancer risk was observed for IS with indications other than MS and used for a short duration (≤2 years) but not for IS indicated only in MS. The absence of risk for prolonged exposure of IS with indications other than MS is not in favor of a causal relation with these drugs.

SET-PP2A complex as a new therapeutic target in KMT2A (MLL) rearranged AML

KMT2A-rearranged (KMT2A-R) is an aggressive and chemo-refractory acute leukemia which mostly affects children. Transcriptomics-based characterization and chemical interrogation identified kinases as key drivers of survival and drug resistance in KMT2A-R leukemia. In contrast, the contribution and regulation of phosphatases is unknown. In this study we uncover the essential role and underlying mechanisms of SET, the endogenous inhibitor of Ser/Thr phosphatase PP2A, in KMT2A-R-leukemia. Investigation of SET expression in acute myeloid leukemia (AML) samples demonstrated that SET is overexpressed, and elevated expression of SET is correlated with poor prognosis and with the expression of MEIS and HOXA genes in AML patients. Silencing SET specifically abolished the clonogenic ability of KMT2A-R leukemic cells and the transcription of KMT2A targets genes HOXA9 and HOXA10. Subsequent mechanistic investigations showed that SET interacts with both KMT2A wild type and fusion proteins, and it is recruited to the HOXA10 promoter. Pharmacological inhibition of SET by FTY720 disrupted SET-PP2A interaction leading to cell cycle arrest and increased sensitivity to chemotherapy in KMT2A-R-leukemic models. Phospho-proteomic analyses revealed that FTY720 reduced the activity of kinases regulated by PP2A, including ERK1, GSK3β, AURB and PLK1 and led to suppression of MYC, supporting the hypothesis of a feedback loop among PP2A, AURB, PLK1, MYC, and SET. Our findings illustrate that SET is a novel player in KMT2A-R leukemia and they provide evidence that SET antagonism could serve as a novel strategy to treat this aggressive leukemia.

Clinical Potential of Immunotherapies in Subarachnoid Hemorrhage Treatment: Mechanistic Dissection of Innate and Adaptive Immune Responses

Subarachnoid hemorrhage (SAH), classified as a medical emergency, is a devastating and severe subtype of stroke. SAH induces an immune response, which further triggers brain injury; however, the underlying mechanisms need to be further elucidated. The current research is predominantly focused on the production of specific subtypes of immune cells, especially innate immune cells, post-SAH onset. Increasing evidence suggests the critical role of immune responses in SAH pathophysiology; however, studies on the role and clinical significance of adaptive immunity post-SAH are limited. In this present study, we briefly review the mechanistic dissection of innate and adaptive immune responses post-SAH. Additionally, we summarized the experimental studies and clinical trials of immunotherapies for SAH treatment, which may form the basis for the development of improved therapeutic approaches for the clinical management of SAH in the future.

Red-Light-Activatable AND-Gated Antitumor Immunosuppressant

Immunosuppressants are emerging as promising candidates for cancer therapy with lower cytotoxicity compared to traditional chemotherapy drugs; yet, the intrinsic side effects such as immunosuppression remain a critical concern. Herein, we introduce a photoactivatable antitumor immunosuppressant called dmBODIPY-FTY720 (BF) that shows no cytotoxicity but can be temporally and locally activated by deep-red light illumination to induce tumor cell apoptosis. To further reduce potential side effects, we integrate BF with another classic photosensitizer called methylene blue (MB) that is activated under the same wavelength of deep-red light (>650 nm) and successfully establish a red-light-activatable AND Boolean logic gate through a mechanism that we found to be synergetic apoptotic induction. At further decreased dosages, deep-red light illumination does not induce cell death in the presence of either BF or MB, but significant cancer cell death is triggered in the presence of both drugs. Therefore, the dosage of BF is further reduced, which will be highly beneficial to minimize any potential side effects of BF. This AND-gated strategy has been successfully applied in vivo for effective suppression of hepatocarcinoma tumors in living mice.

Evaluation of Temozolomide and Fingolimod Treatments in Glioblastoma Preclinical Models

Glioblastomas are malignant brain tumors which remain lethal due to their aggressive and invasive nature. The standard treatment combines surgical resection, radiotherapy, and chemotherapy using Temozolomide, albeit with a minor impact on patient prognosis (15 months median survival). New therapies evaluated in preclinical translational models are therefore still required to improve patient survival and quality of life. In this preclinical study, we evaluated the effect of Temozolomide in different models of glioblastoma. We also aimed to investigate the efficacy of Fingolimod, an immunomodulatory drug for multiple sclerosis also described as an inhibitor of the sphingosine-1-phosphate (S1P)/S1P receptor axis. The effects of Fingolimod and Temozolomide were analyzed with in vitro 2D and 3D cellular assay and in vivo models using mouse and human glioblastoma cells implanted in immunocompetent or immunodeficient mice, respectively. We demonstrated both in in vitro and in vivo models that Temozolomide has a varied effect depending on the tumor type (i.e., U87MG, U118MG, U138MG, and GL261), demonstrating sensitivity, acquired resistance, and purely resistant tumor phenotypes, as observed in patients. Conversely, Fingolimod only reduced in vitro 2D tumor cell growth and increased cytotoxicity. Indeed, Fingolimod had little or no effect on 3D spheroid cytotoxicity and was devoid of effect on in vivo tumor progression in Temozolomide-sensitive models. These results suggest that the efficacy of Fingolimod is dependent on the glioblastoma tumor microenvironment. Globally, our data suggest that the response to Temozolomide varies depending on the cancer model, consistent with its clinical activity, whereas the potential activity of Fingolimod may merit further evaluation.

Actin-binding protein Filamin B regulates the cell-surface retention of endothelial sphingosine 1-phosphate receptor 1

Sphingosine 1-phosphate receptor 1 (S1PR1) is a G protein-coupled receptor essential for vascular development and postnatal vascular homeostasis. When exposed to sphingosine 1-phosphate (S1P) in the blood of ∼1 μM, S1PR1 in endothelial cells retains cell-surface localization, while lymphocyte S1PR1 shows almost complete internalization, suggesting the cell-surface retention of S1PR1 is endothelial cell-specific. To identify regulating factors that function to retain S1PR1 on the endothelial cell surface, here we utilized an enzyme-catalyzed proximity labeling technique followed by proteomic analyses. We identified Filamin B (FLNB), an actin-binding protein involved in F-actin cross-linking, as a candidate regulating protein. We show FLNB knockdown by RNA interference induced massive internalization of S1PR1 into early endosomes, which was partially ligand-dependent and required receptor phosphorylation. Further investigation showed FLNB was also important for the recycling of internalized S1PR1 back to the cell surface. FLNB knockdown did not affect the localization of S1PR3, another S1P receptor subtype expressed in endothelial cells, nor did it affect localization of ectopically expressed β2-adrenergic receptor. Functionally, we show FLNB knockdown in endothelial cells impaired S1P-induced intracellular phosphorylation events and directed cell migration and enhancement of the vascular barrier. Taken together, our results demonstrate that FLNB is a novel regulator critical for S1PR1 cell-surface localization and thereby proper endothelial cell function.

Autophagy and Breast Cancer: Connected in Growth, Progression, and Therapy

Despite an increase in the incidence of breast cancer worldwide, overall prognosis has been consistently improving owing to the development of multiple targeted therapies and novel combination regimens including endocrine therapies, aromatase inhibitors, Her2-targeted therapies, and cdk4/6 inhibitors. Immunotherapy is also being actively examined for some breast cancer subtypes. This overall positive outlook is marred by the development of resistance or reduced efficacy of the drug combinations, but the underlying mechanisms are somewhat unclear. It is interesting to note that cancer cells quickly adapt and evade most therapies by activating autophagy, a catabolic process designed to recycle damaged cellular components and provide energy. In this review, we discuss the role of autophagy and autophagy-associated proteins in breast cancer growth, drug sensitivity, tumor dormancy, stemness, and recurrence. We further explore how autophagy intersects and reduces the efficacy of endocrine therapies, targeted therapies, radiotherapy, chemotherapies as well as immunotherapy via modulating various intermediate proteins, miRs, and lncRNAs. Lastly, the potential application of autophagy inhibitors and bioactive molecules to improve the anticancer effects of drugs by circumventing the cytoprotective autophagy is discussed.

S1P1 Threonine 236 Phosphorylation Mediates the Invasiveness of Triple-Negative Breast Cancer and Sensitivity to FTY720

Hyperactive sphingosine 1-phosphate (S1P) signaling is associated with a poor prognosis of triple-negative breast cancer (TNBC). Despite recent evidence that links the S1P receptor 1 (S1P1) to TNBC cell survival, its role in TNBC invasion and the underlying mechanisms remain elusive. Combining analyses of human TNBC cells with zebrafish xenografts, we found that phosphorylation of S1P receptor 1 (S1P1) at threonine 236 (T236) is critical for TNBC dissemination. Compared to luminal breast cancer cells, TNBC cells exhibit a significant increase of phospho-S1P1 T236 but not the total S1P1 levels. Misexpression of phosphorylation-defective S1P1 T236A (alanine) decreases TNBC cell migration in vitro and disease invasion in zebrafish xenografts. Pharmacologic disruption of S1P1 T236 phosphorylation, using either a pan-AKT inhibitor (MK2206) or an S1P1 functional antagonist (FTY720, an FDA-approved drug for treating multiple sclerosis), suppresses TNBC cell migration in vitro and tumor invasion in vivo. Finally, we show that human TNBC cells with AKT activation and elevated phospho-S1P1 T236 are sensitive to FTY720-induced cytotoxic effects. These findings indicate that the AKT-enhanced phosphorylation of S1P1 T236 mediates much of the TNBC invasiveness, providing a potential biomarker to select TNBC patients for the clinical application of FTY720.

Fingolimod ameliorates chronic experimental autoimmune neuritis by modulating inflammatory cytokines and Akt/mTOR/NF-κB signaling

OBJECTIVE

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disease that targets the myelin sheaths of the peripheral nerves. Fingolimod is a sphingosine 1 phosphate (S1P) receptor antagonist with a high affinity for S1P receptors through the Akt-mTOR pathway, and prior research has suggested that it might be helpful in autoimmune illnesses.

METHODS

Chronic experimental autoimmune neuritis (c-EAN) was induced by immunizing Lewis rats with the S-palm P0(180-199) peptide, and then the treatment group was intraperitoneally injected with fingolimod (1 mg/kg) daily. Hematoxylin and eosin staining was used to assess the severity of nerve injury. Immunohistochemistry staining showed that fingolimod's anti-inflammatory effects on c-EAN rats might be realized through the NF-κB signaling pathway. Tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-1beta (IL-1β), interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), and intercellular adhesion molecule-1 (ICAM-1) were measured to evaluate the inflammation levels, and pAkt, p-S6, and p-p65 were used to measure the abundance of downstream activation markers to determine whether the Akt/mTOR/NF-κB signaling pathway was activated in the c-EAN model.

RESULTS

Fingolimod treatment reduced the inflammatory reaction and the expression of NF-κB in sciatic nerves. It also decreased the mRNA levels of the proinflammatory cytokines TNF-α, IFN-γ, IL-1β, IL-6, iNOS, and ICAM-1 and pAkt, p-S6, and p-p65, representing the Akt/mTOR/NF-κB signaling pathway.

CONCLUSION

Our data showed that fingolimod could improve the disease course, alleviate the decrease in inflammation, and reduce proinflammatory cytokines through the Akt/mTOR/NF-κB axis in c-EAN rats, which could be beneficial for the development of CIDP-related research.

Adverse effect of FTY720P on colonic Na+ /K+ ATPase is mediated via ERK, p38MAPK, PKC, and PI3K

FTY720P, an analogue of sphingosine 1-phosphate, has emerged lately as a potential causative agent of inflammatory bowel disease, in which electrolytes movements driven by the sodium gradient established by the Na⁺ /K⁺ ATPase are altered. We showed previously in Caco-2 cells, a 50% FTY720P-induced decrease in the ATPase activity, mediated via S1PR2 and PGE2. This work aims at delineating the mechanism underlying PGE2 release and at investigating if the ATPase inhibition is due to changes in its abundance. The activity of the ATPase and the localization of a GFP-tagged Na⁺ /K⁺ -ATPase α₁ -subunit were assessed in cells treated with 7.5 nM FTY720P. The involvement of ERK, p38 MAPK, PKC, and PI3K was studied in cells treated with 7.5 nM FTY720P or 1 nM PGE2 in presence of their inhibitors, or by determining changes in the protein expression of their activated phosphorylated forms. Imaging data showed ∼30% reduction in the GFP-tagged Na⁺ /K⁺ ATPase at the plasma membrane. Both FTY720P and PGE2 showed, respectively, 50% and 60% reduction in ATPase activity that disappeared when p38 MAPK, PKC, and PI3K were inhibited individually but not with ERK inhibition. The effect of FTY720P was imitated by PMA, an activator of PKC. Western blotting revealed inhibition of ERK by FTY720P. It was concluded that FTY720P, through activation of S1PR2, downregulates the Na⁺ /K⁺ ATPase by inhibiting ERK, which in turn activates p38 MAPK leading to the sequential activation of PKC and PI3K, PGE2 release, and a decrease in the Na⁺ /K⁺ ATPase activity and membrane abundance.

Photonic and magnetic materials for on-demand local drug delivery

Nanomedicine has been considered a promising tool for biomedical research and clinical practice in the 21st century because of the great impact nanomaterials could have on human health. The generation of new smart nanomaterials, which enable time- and space-controlled drug delivery, improve the limitations of conventional treatments, such as non-specific targeting, poor biodistribution and permeability. These smart nanomaterials can respond to internal biological stimuli (pH, enzyme expression and redox potential) and/or external stimuli (such as temperature, ultrasound, magnetic field and light) to further the precision of therapies. To this end, photonic and magnetic nanoparticles, such as gold, silver and iron oxide, have been used to increase sensitivity and responsiveness to external stimuli. In this review, we aim to report the main and most recent systems that involve photonic or magnetic nanomaterials for external stimulus-responsive drug release. The uniqueness of this review lies in highlighting the versatility of integrating these materials within different carriers. This leads to enhanced performance in terms of in vitro and in vivo efficacy, stability and toxicity. We also point out the current regulatory challenges for the translation of these systems from the bench to the bedside, as well as the yet unresolved matter regarding the standardization of these materials.

Plasma membrane phospholipid phosphatase-related proteins as pleiotropic regulators of neuron growth and excitability

Neuronal plasma membrane proteins are essential for integrating cell extrinsic and cell intrinsic signals to orchestrate neuronal differentiation, growth and plasticity in the developing and adult nervous system. Here, we shed light on the family of plasma membrane proteins phospholipid phosphatase-related proteins (PLPPRs) (alternative name, PRGs; plasticity-related genes) that fine-tune neuronal growth and synaptic transmission in the central nervous system. Several studies uncovered essential functions of PLPPRs in filopodia formation, axon guidance and branching during nervous system development and regeneration, as well as in the control of dendritic spine number and excitability. Loss of PLPPR expression in knockout mice increases susceptibility to seizures, and results in defects in sensory information processing, development of psychiatric disorders, stress-related behaviors and abnormal social interaction. However, the exact function of PLPPRs in the context of neurological diseases is largely unclear. Although initially described as active lysophosphatidic acid (LPA) ecto-phosphatases that regulate the levels of this extracellular bioactive lipid, PLPPRs lack catalytic activity against LPA. Nevertheless, they emerge as atypical LPA modulators, by regulating LPA mediated signaling processes. In this review, we summarize the effects of this protein family on cellular morphology, generation and maintenance of cellular protrusions as well as highlight their known neuronal functions and phenotypes of KO mice. We discuss the molecular mechanisms of PLPPRs including the deployment of phospholipids, actin-cytoskeleton and small GTPase signaling pathways, with a focus on identifying gaps in our knowledge to stimulate interest in this understudied protein family.

Harnessing the power of sphingolipids: Prospects for acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive, heterogenous malignancy characterized by clonal expansion of bone marrow-derived myeloid progenitor cells. While our current understanding of the molecular and genomic landscape of AML has evolved dramatically and opened avenues for molecularly targeted therapeutics to improve upon standard intensive induction chemotherapy, curative treatments are elusive, particularly in older patients. Responses to current AML treatments are transient and incomplete, necessitating the development of novel treatment strategies to improve outcomes. To this end, harnessing the power of bioactive sphingolipids to treat cancer shows great promise. Sphingolipids are involved in many hallmarks of cancer of paramount importance in AML. Leukemic blast survival is influenced by cellular levels of ceramide, a bona fide pro-death molecule, and its conversion to signaling molecules such as sphingosine-1-phosphate and glycosphingolipids. Preclinical studies demonstrate the efficacy of therapeutics that target dysregulated sphingolipid metabolism as well as their combinatorial synergy with clinically-relevant therapeutics. Thus, increased understanding of sphingolipid dysregulation may be exploited to improve AML patient care and outcomes. This review summarizes the current knowledge of dysregulated sphingolipid metabolism in AML, evaluates how pro-survival sphingolipids promote AML pathogenesis, and discusses the therapeutic potential of targeting these dysregulated sphingolipid pathways.

Fingolimod exerts in vitro anticancer activity against hepatocellular carcinoma cell lines via YAP/TAZ suppression

Hepatocellular carcinoma (HCC) remains a notably global health challenge with high mortality rates and poor prognosis. The deregulation of the Hippo signalling pathway, especially the overexpression and activation of downstream effector Yes-associated protein (YAP), has been demonstrated to result in the rapid malignant evolution of HCC. In this context, multiple efforts have been dedicated to targeting YAP for HCC therapy, but effective YAP inhibitors are still lacking. In this study, through a YAP-TEAD (8×GTIIC) luciferase reporter assay, we identified fingolimod, an immunomodulatory drug approved for the treatment of multiple sclerosis, as a novel YAP inhibitor. Fingolimod suppressed the proliferation of HCC cell lines by downregulating the protein levels as well as the trans-activating function of YAP. Overall, our current study not only identifies fingolimod as a novel YAP-targeting in hibitor, but also indicates that this clinically-approved drug could be utilized as a potential and feasible therapeutic drug for HCC.

The key role of sphingolipid metabolism in cancer: New therapeutic targets, diagnostic and prognostic values, and anti-tumor immunotherapy resistance

Biologically active sphingolipids are closely related to the growth, differentiation, aging, and apoptosis of cancer cells. Some sphingolipids, such as ceramides, are favorable metabolites in the sphingolipid metabolic pathway, usually mediating antiproliferative responses, through inhibiting cancer cell growth and migration, as well as inducing autophagy and apoptosis. However, other sphingolipids, such as S1P, play the opposite role, which induces cancer cell transformation, migration and growth and promotes drug resistance. There are also other sphingolipids, as well as enzymes, played potentially critical roles in cancer physiology and therapeutics. This review aimed to explore the important roles of sphingolipid metabolism in cancer. In this article, we summarized the role and value of sphingolipid metabolism in cancer, including the distribution of sphingolipids, the functions, and their relevance to cancer diagnosis and prognosis. We also summarized the known and potential antitumor targets present in sphingolipid metabolism, analyzed the correlation between sphingolipid metabolism and tumor immunity, and summarize the antitumor effects of natural compounds based on sphingolipids. Through the analysis and summary of sphingolipid antitumor therapeutic targets and immune correlation, we aim to provide ideas for the development of new antitumor drugs, exploration of new therapeutic means for tumors, and study of immunotherapy resistance mechanisms.

Therapeutic Potential of Fingolimod and Dimethyl Fumarate in Non-Small Cell Lung Cancer Preclinical Models

New therapies are required for patients with non-small cell lung cancer (NSCLC) for which the current standards of care poorly affect the patient prognosis of this aggressive cancer subtype. In this preclinical study, we aim to investigate the efficacy of Fingolimod, a described inhibitor of sphingosine-1-phosphate (S1P)/S1P receptors axis, and Dimethyl Fumarate (DMF), a methyl ester of fumaric acid, both already approved as immunomodulators in auto-immune diseases with additional expected anti-cancer effects. The impact of both drugs was analyzed with in vitro cell survival analysis and in vivo graft models using mouse and human NSCLC cells implanted in immunocompetent or immunodeficient mice, respectively. We demonstrated that Fingolimod and DMF repressed tumor progression without apparent adverse effects in vivo in three preclinical mouse NSCLC models. In vitro, Fingolimod did not affect either the tumor proliferation or the cytotoxicity, although DMF reduced tumor cell proliferation. These results suggest that Fingolimod and DMF affected tumor progression through different cellular mechanisms within the tumor microenvironment. Fingolimod and DMF might uncover potential therapeutic opportunities in NSCLC.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

Role of Sphingolipids in Multiple Myeloma Progression, Drug Resistance, and Their Potential as Therapeutic Targets

Multiple myeloma (MM) is an incapacitating hematological malignancy characterized by accumulation of cancerous plasma cells in the bone marrow (BM) and production of an abnormal monoclonal protein (M-protein). The BM microenvironment has a key role in myeloma development by facilitating the growth of the aberrant plasma cells, which eventually interfere with the homeostasis of the bone cells, exacerbating osteolysis and inhibiting osteoblast differentiation. Recent recognition that metabolic reprograming has a major role in tumor growth and adaptation to specific changes in the microenvironmental niche have led to consideration of the role of sphingolipids and the enzymes that control their biosynthesis and degradation as critical mediators of cancer since these bioactive lipids have been directly linked to the control of cell growth, proliferation, and apoptosis, among other cellular functions. In this review, we present the recent progress of the research investigating the biological implications of sphingolipid metabolism alterations in the regulation of myeloma development and its progression from the pre-malignant stage and discuss the roles of sphingolipids in in MM migration and adhesion, survival and proliferation, as well as angiogenesis and invasion. We introduce the current knowledge regarding the role of sphingolipids as mediators of the immune response and drug-resistance in MM and tackle the new developments suggesting the manipulation of the sphingolipid network as a novel therapeutic direction for MM.

Splicing deregulation, microRNA and Notch aberrations: fighting the three-headed dog to overcome drug resistance in malignant mesothelioma

INTRODUCTION

Malignant mesothelioma (MMe) is an aggressive rare cancer of the mesothelium, associated with asbestos exposure. MMe is currently an incurable disease at all stages mainly due to resistance to treatments. It is therefore necessary to elucidate key mechanisms underlying chemoresistance, in an effort to exploit them as novel therapeutic targets.

AREAS COVERED

Chemoresistance is frequently elicited by microRNA (miRNA) alterations and splicing deregulations. Indeed, several miRNAs, such as miR-29c, have been shown to exert oncogenic or oncosuppressive activity. Alterations in the splicing machinery might also be involved in chemoresistance. Moreover, the Notch signaling pathway, often deregulated in MMe, plays a key role in cancer stem cells formation and self-renewal, leading to drug resistance and relapses.

EXPERT OPINION

The prognosis of MMe in patients varies among different tumors and patient characteristics, and novel biomarkers and therapies are warranted. This work aims at giving an overview of MMe, with a special focus on state-of-the-art treatments and new therapeutic strategies against vulnerabilities emerging from studies on epigenetics factors. Besides, this review is also the first to discuss the interplay between miRNAs and alternative splicing as well as the role of Notch as new promising frontiers to overcome drug resistance in MMe.

Sphingolipids and Lymphomas: A Double-Edged Sword

Lymphomas are a highly heterogeneous group of hematological neoplasms. Given their ethiopathogenic complexity, their classification and management can become difficult tasks; therefore, new approaches are continuously being sought. Metabolic reprogramming at the lipid level is a hot topic in cancer research, and sphingolipidomics has gained particular focus in this area due to the bioactive nature of molecules such as sphingoid bases, sphingosine-1-phosphate, ceramides, sphingomyelin, cerebrosides, globosides, and gangliosides. Sphingolipid metabolism has become especially exciting because they are involved in virtually every cellular process through an extremely intricate metabolic web; in fact, no two sphingolipids share the same fate. Unsurprisingly, a disruption at this level is a recurrent mechanism in lymphomagenesis, dissemination, and chemoresistance, which means potential biomarkers and therapeutical targets might be hiding within these pathways. Many comprehensive reviews describing their role in cancer exist, but because most research has been conducted in solid malignancies, evidence in lymphomagenesis is somewhat limited. In this review, we summarize key aspects of sphingolipid biochemistry and discuss their known impact in cancer biology, with a particular focus on lymphomas and possible therapeutical strategies against them.

Fingolimod (FTY720), a Sphinogosine-1-Phosphate Receptor Agonist, Mitigates Choroidal Endothelial Proangiogenic Properties and Choroidal Neovascularization

Neovascular or wet age-related macular degeneration (nAMD) causes vision loss due to inflammatory and vascular endothelial growth factor (VEGF)-driven neovascularization processes in the choroid. Due to the excess in VEGF levels associated with nAMD, anti-VEGF therapies are utilized for treatment. Unfortunately, not all patients have a sufficient response to such therapies, leaving few if any other treatment options for these patients. Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator found in endothelial cells that participates in modulating barrier function, angiogenesis, and inflammation. S1P, through its receptor (S1PR1) in endothelial cells, prevents illegitimate sprouting angiogenesis during vascular development. In the present paper, we show that, in choroidal endothelial cells, S1PR1 is the most abundantly expressed S1P receptor and agonism of S1PR1-prevented choroidal endothelial cell capillary morphogenesis in culture. Given that nAMD pathogenesis draws from enhanced inflammation and angiogenesis as well as a loss of barrier function, we assessed the impact of S1PR agonism on choroidal neovascularization in vivo. Using laser photocoagulation rupture of Bruch’s membrane to induce choroidal neovascularization, we show that S1PR non-selective (FTY720) and S1PR1 selective (CYM5442) agonists significantly inhibit choroidal neovascularization in this model. Thus, utilizing S1PR agonists to temper choroidal neovascularization presents an additional novel use for these agonists presently in clinical use for multiple sclerosis as well as other inflammatory diseases.

Molecular Pharmacology and Novel Potential Therapeutic Applications of Fingolimod

Fingolimod is a well-tolerated, highly effective disease-modifying therapy successfully utilized in the management of multiple sclerosis. The active metabolite, fingolimod-phosphate, acts on sphingosine-1-phosphate receptors (S1PRs) to bring about an array of pharmacological effects. While being initially recognized as a novel agent that can profoundly reduce T-cell numbers in circulation and the CNS, thereby suppressing inflammation and MS, there is now rapidly increasing knowledge on its previously unrecognized molecular and potential therapeutic effects in diverse pathological conditions. In addition to exerting inhibitory effects on sphingolipid pathway enzymes, fingolimod also inhibits histone deacetylases, transient receptor potential cation channel subfamily M member 7 (TRMP7), cytosolic phospholipase A2α (cPLA2α), reduces lysophosphatidic acid (LPA) plasma levels, and activates protein phosphatase 2A (PP2A). Furthermore, fingolimod induces apoptosis, autophagy, cell cycle arrest, epigenetic regulations, macrophages M1/M2 shift and enhances BDNF expression. According to recent evidence, fingolimod modulates a range of other molecular pathways deeply rooted in disease initiation or progression. Experimental reports have firmly associated the drug with potentially beneficial therapeutic effects in immunomodulatory diseases, CNS injuries, and diseases including Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, and even cancer. Attractive pharmacological effects, relative safety, favorable pharmacokinetics, and positive experimental data have collectively led to its testing in clinical trials. Based on the recent reports, fingolimod may soon find its way as an adjunct therapy in various disparate pathological conditions. This review summarizes the up-to-date knowledge about molecular pharmacology and potential therapeutic uses of fingolimod.

FTY720 in resistant human epidermal growth factor receptor 2-positive breast cancer

The prognosis of patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer has considerably improved. However, no reliable treatment besides anti-HER2 strategies has been available. FTY720, a small-molecule compound used for treating refractory multiple sclerosis, has been reported to have beneficial effects against cancers. We therefore evaluated the efficacy of FTY720 in trastuzumab-resistant breast cancer cells and investigated the possible mechanism involved. This study evaluated morphological changes after FTY720 treatment. Antiproliferative WST-1 assays and LDH Cytotoxicity Assay Kits were used to determine the treatment effects of drugs, whereas Western blot analysis was used to evaluate protein expression. Apoptotic events were investigated through annexin V staining and TUNEL assays using flow cytometry. FTY720 was effective in trastuzumab-resistant breast cancer cell lines despite the presence of PIK3CA mutation. Studied on a xenograft mouse model, FTY720-treated groups had statistically significantly poorer HCC1954 xenograft growth in vivo compared with the control group. Our findings suggest that FTY720 can overcome resistance to trastuzumab therapy in patients with HER2-positive breast cancer, with FTY720 plus trastuzumab might offer even better efficacy in vitro and in vivo.

Lysosome‑targeted drug combination induces multiple organelle dysfunctions and non‑canonical death in pancreatic cancer cells

Pancreatic cancer is one of the leading causes of cancer-related mortality and has the lowest 5-year survival rate. Therefore, novel strategies are urgently required to treat pancreatic cancer. Pancreatic ductal adenocarcinoma (PDAC) cells rely on enhanced lysosomal function for survival and proliferation to facilitate the degradation of contents accumulated via autophagy and macropinocytosis. Previously, we have reported that the combination of epidermal growth factor receptor/HER2 inhibitor lapatinib and sphingosine analog fingolimod (FTY720) confers a significant cytostatic effect in lung cancer cells. In the present study, the combined effects of these drugs on PDAC cell lines, BxPC-3, KP-4, PANC-1 and MIA PaCa-2, were examined. It was observed that FTY720 enhanced the lapatinib-induced cytotoxic effect and caused non-canonical and lysosome-dependent death in PDAC cells. Lapatinib and FTY720 induced lysosomal swelling and inhibited lysosomal acidification. Combination treatment with lapatinib and FTY720 increased lysosomal membrane permeability, induced mitochondrial depolarization, induced endoplasmic reticulum stress and disturbed intracellular calcium homeostasis. Additionally, the cytotoxic effect of lapatinib was enhanced by hydroxychloroquine or the CDK4/6 inhibitor abemaciclib, both of which induce lysosomal dysfunction. Collectively, these results indicated that the lysosome-targeted drug combination induces multiple organelle dysfunction and exerts a marked cytotoxic effect in PDAC cells.

Differential Expression of the Sphingolipid Pathway Is Associated with Sensitivity to the PP2A Activator FTY720 in Colorectal Cancer Cell Lines

Protein phosphatase 2A (PP2A) is a ubiquitously expressed intracellular serine/threonine phosphatase. Deregulation of PP2A is a common event associated with adenocarcinomas of the colon and rectum. We have previously shown that breast cancer cell lines are sensitive to the PP2A activator FTY720, and that sensitivity is predicted by high Aurora kinase A (AURKA) mRNA expression. In this study, we hypothesized that high relative AURKA expression could predict sensitivity to FTY720-induced apoptosis in colorectal cancer (CRC). The CRC cell lines NCI H716, COLO320DM, DLD-1, SW480, and HT-29 show a high relative AURKA expression as compared to LS411N, T84, HCT116, SW48, and LOVO. Following viability assays, LS411N, T84, HCT116, and SW480 were shown to be sensitive to FTY720, whereas DLD-1 and HT-29 were non-sensitive. Hence, AURKA mRNA expression does not predict sensitivity to FTY720 in CRC cell lines. Differentially expressed genes (DEGs) were obtained by comparing the sensitive CRC cell lines (LS411N and HCT116) against the non-sensitive (HT-29 and DLD-1). We found that 253 genes were significantly altered in expression, and upregulation of CERS4, PPP2R2C, GNAZ, PRKCG, BCL2, MAPK12, and MAPK11 suggests the involvement of the sphingolipid signaling pathway, known to be activated by phosphorylated-FTY720. In conclusion, although AURKA expression did not predict sensitivity to FTY720, it is evident that specific CRC cell lines are sensitive to 5 µM FTY720, potentially because of the differential expression of genes involved in the sphingolipid pathway.

A Dansyl-Modified Sphingosine Kinase Inhibitor DPF-543 Enhanced De Novo Ceramide Generation

Sphingosine-1-phosphate (S1P) synthesized by sphingosine kinase (SPHK) is a signaling molecule, involved in cell proliferation, growth, differentiation, and survival. Indeed, a sharp increase of S1P is linked to a pathological outcome with inflammation, cancer metastasis, or angiogenesis, etc. In this regard, SPHK/S1P axis regulation has been a specific issue in the anticancer strategy to turn accumulated sphingosine (SPN) into cytotoxic ceramides (Cers). For these purposes, there have been numerous chemicals synthesized for SPHK inhibition. In this study, we investigated the comparative efficiency of dansylated PF-543 (DPF-543) on the Cers synthesis along with PF-543. DPF-543 deserved attention in strong cytotoxicity, due to the cytotoxic Cers accumulation by ceramide synthase (CerSs). DPF-543 exhibited dual actions on Cers synthesis by enhancing serine palmitoyltransferase (SPT) activity, and by inhibiting SPHKs, which eventually induced an unusual environment with a high amount of 3-ketosphinganine and sphinganine (SPA). SPA in turn was consumed to synthesize Cers via de novo pathway. Interestingly, PF-543 increased only the SPN level, but not for SPA. In addition, DPF-543 mildly activates acid sphingomyelinase (aSMase), which contributes a partial increase in Cers. Collectively, a dansyl-modified DPF-543 relatively enhanced Cers accumulation via de novo pathway which was not observed in PF-543. Our results demonstrated that the structural modification on SPHK inhibitors is still an attractive anticancer strategy by regulating sphingolipid metabolism.

Unraveling the mechanisms of chemotherapy-induced damage to human primordial follicle reserve: road to developing therapeutics for fertility preservation and reversing ovarian aging

Among the investigated mechanisms of chemotherapy-induced damage to human primordial follicle reserve are induction of DNA double-strand breaks (DSBs) and resultant apoptotic death, stromal-microvascular damage and follicle activation. Accumulating basic and translational evidence suggests that acute exposure to gonadotoxic chemotherapeutics, such as cyclophosphamide or doxorubicin, induces DNA DSBs and triggers apoptotic death of primordial follicle oocytes within 12-24 h, resulting in the massive loss of ovarian reserve. Evidence also indicates that chemotherapeutic agents can cause microvascular and stromal damage, induce hypoxia and indirectly affect ovarian reserve. While it is possible that the acute reduction of the primordial follicle reserve by massive apoptotic losses may result in delayed activation of some primordial follicles, this is unlikely to be a predominant mechanism of loss in humans. Here, we review these mechanisms of chemotherapy-induced ovarian reserve depletion and the potential reasons for the discrepancies among the studies. Based on the current literature, we propose an integrated hypothesis that explains both the acute and delayed chemotherapy-induced loss of primordial follicle reserve in the human ovary.

Synthesis and Biological Evaluation of Fingolimod Derivatives as Antibacterial Agents

We recently identified fingolimod as a potent antibiofilm compound by screening FDA-approved drugs. To study if the antibacterial activity of fingolimod could be further improved and to explore in-depth structure-activity relationships, we synthesized 28 novel fingolimod derivatives and evaluated their efficacy against Staphylococcus aureus grown in planktonic/single cell and biofilms. The most effective derivatives were tested on preformed S. aureus biofilms and against Gram-negative bacteria Acinetobacter baumannii and Pseudomonas aeruginosa, using fingolimod as the reference compound. Seven derivatives were more effective against S. aureus, while five other derivatives showed improved activity against P. aeruginosa and/or A. baumannii, with no apparent change in cytotoxicity on human cells. The most interesting derivatives, compounds 43 and 55, displayed a broader spectrum of antibacterial activity, possibly exerted by the change of the para-hydrocarbon chain to a meta position for 43 and by an additional hydroxyl group for 55.

Ceramide Metabolism Enzymes-Therapeutic Targets against Cancer

Sphingolipids are both structural molecules that are essential for cell architecture and second messengers that are involved in numerous cell functions. Ceramide is the central hub of sphingolipid metabolism. In addition to being the precursor of complex sphingolipids, ceramides induce cell cycle arrest and promote cell death and inflammation. At least some of the enzymes involved in the regulation of sphingolipid metabolism are altered in carcinogenesis, and some are targets for anticancer drugs. A number of scientific reports have shown how alterations in sphingolipid pools can affect cell proliferation, survival and migration. Determination of sphingolipid levels and the regulation of the enzymes that are implicated in their metabolism is a key factor for developing novel therapeutic strategies or improving conventional therapies. The present review highlights the importance of bioactive sphingolipids and their regulatory enzymes as targets for therapeutic interventions with especial emphasis in carcinogenesis and cancer dissemination.

The targetable nanoparticle BAF312@cRGD-CaP-NP represses tumor growth and angiogenesis by downregulating the S1PR1/P-STAT3/VEGFA axis in triple-negative breast cancer

Background

Overexpressed vascular endothelial growth factor A (VEGFA) and phosphorylated signal transducer and activator of transcription 3 (P-STAT3) cause unrestricted tumor growth and angiogenesis of breast cancer (BRCA), especially triple-negative breast cancer (TNBC). Hence, novel treatment strategy is urgently needed.

Results

We found sphingosine 1 phosphate receptor 1 (S1PR1) can regulate P-STAT3/VEGFA. Database showed S1PR1 is highly expressed in BRCA and causes the poor prognosis of patients. Interrupting the expression of S1PR1 could inhibit the growth of human breast cancer cells (MCF-7 and MDA-MB-231) and suppress the angiogenesis of human umbilical vein endothelial cells (HUVECs) via affecting S1PR1/P-STAT3/VEGFA axis. Siponimod (BAF312) is a selective antagonist of S1PR1, which inhibits tumor growth and angiogenesis in vitro by downregulating the S1PR1/P-STAT3/VEGFA axis. We prepared pH-sensitive and tumor-targeted shell-core structure nanoparticles, in which hydrophilic PEG2000 modified with the cyclic Arg-Gly-Asp (cRGD) formed the shell, hydrophobic DSPE formed the core, and CaP (calcium and phosphate ions) was adsorbed onto the shell; the nanoparticles were used to deliver BAF312 (BAF312@cRGD-CaP-NPs). The size and potential of the nanoparticles were 109.9 ± 1.002 nm and − 10.6 ± 0.056 mV. The incorporation efficacy for BAF312 was 81.4%. Results confirmed BAF312@cRGD-CaP-NP could dramatically inhibit tumor growth and angiogenesis in vitro and in MDA-MB-231 tumor-bearing mice via downregulating the S1PR1/P-STAT3/VEGFA axis.

Conclusions

Our data suggest a potent role for BAF312@cRGD-CaP-NPs in treating BRCA, especially TNBC by downregulating the S1PR1/P-STAT3/VEGFA axis.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00904-6.

The Impact of Dietary Sphingolipids on Intestinal Microbiota and Gastrointestinal Immune Homeostasis

The large surfaces of gastrointestinal (GI) organs are well adapted to their diverse tasks of selective nutritional uptake and defense against the external environment. To maintain a functional balance, a vast number of immune cells is located within the mucosa. A strictly regulated immune response is required to impede constant inflammation and to maintain barrier function. An increasing prevalence of GI diseases has been reported in Western societies over the past decades. This surge in GI disorders has been linked to dietary changes followed by an imbalance of the gut microbiome, leading to a chronic, low grade inflammation of the gut epithelium. To counteract the increasing health care costs associated with diseases, it is paramount to understand the mechanisms driving immuno-nutrition, the associations between nutritional compounds, the commensal gut microbiota, and the host immune response. Dietary compounds such as lipids, play a central role in GI barrier function. Bioactive sphingolipids (SLs), e.g. sphingomyelin (SM), sphingosine (Sph), ceramide (Cer), sphingosine-1- phosphate (S1P) and ceramide-1-phosphate (C1P) may derive from dietary SLs ingested through the diet. They are not only integral components of cell membranes, they additionally modulate cell trafficking and are precursors for mediators and second messenger molecules. By regulating intracellular calcium levels, cell motility, cell proliferation and apoptosis, SL metabolites have been described to influence GI immune homeostasis positively and detrimentally. Furthermore, dietary SLs are suggested to induce a shift in the gut microbiota. Modes of action range from competing with the commensal bacteria for intestinal cell attachment to prevention from pathogen invasion by regulating innate and immediate defense mechanisms. SL metabolites can also be produced by gut microorganisms, directly impacting host metabolic pathways. This review aims to summarize recent findings on SL signaling and functional variations of dietary SLs. We highlight novel insights in SL homeostasis and SL impact on GI barrier function, which is directly linked to changes of the intestinal microbiota. Knowledge gaps in current literature will be discussed to address questions relevant for understanding the pivotal role of dietary SLs on chronic, low grade inflammation and to define a balanced and healthy diet for disease prevention and treatment.

Targeting the Sphingosine Kinase/Sphingosine-1-Phosphate Signaling Axis in Drug Discovery for Cancer Therapy

Sphingolipid metabolites have emerged as critical players in the regulation of various physiological processes. Ceramide and sphingosine induce cell growth arrest and apoptosis, whereas sphingosine-1-phosphate (S1P) promotes cell proliferation and survival. Here, we present an overview of sphingolipid metabolism and the compartmentalization of various sphingolipid metabolites. In addition, the sphingolipid rheostat, a fine metabolic balance between ceramide and S1P, is discussed. Sphingosine kinase (SphK) catalyzes the synthesis of S1P from sphingosine and modulates several cellular processes and is found to be essentially involved in various pathophysiological conditions. The regulation and biological functions of SphK isoforms are discussed. The functions of S1P, along with its receptors, are further highlighted. The up-regulation of SphK is observed in various cancer types and is also linked to radio- and chemoresistance and poor prognosis in cancer patients. Implications of the SphK/S1P signaling axis in human pathologies and its inhibition are discussed in detail. Overall, this review highlights current findings on the SphK/S1P signaling axis from multiple angles, including their functional role, mechanism of activation, involvement in various human malignancies, and inhibitor molecules that may be used in cancer therapy.

A genome-scale CRISPR Cas9 dropout screen identifies synthetically lethal targets in SRC-3 inhibited cancer cells

Steroid receptor coactivator 3 (SRC-3/NCoA3/AIB1), is a key regulator of gene transcription and it plays a central role in breast cancer (BC) tumorigenesis, making it a potential therapeutic target. Beyond its function as an important regulator of estrogen receptor transcriptional activity, SRC-3 also functions as a coactivator for a wide range of other transcription factors, suggesting SRC-3 inhibition can be beneficial in hormone-independent cancers as well. The recent discovery of a potent SRC-3 small molecule inhibitor, SI-2, enabled the further development of additional related compounds. SI-12 is an improved version of SI-2 that like SI-2 has anti-proliferative activity in various cancer types, including BC. Here, we sought to identify gene targets, that when inhibited in the presence of SI-12, would lead to enhanced BC cell cytotoxicity. We performed a genome-scale CRISPR-Cas9 screen in MCF-7 BC cells under conditions of pharmacological pressure with SI-12. A parallel screen was performed with an ER inhibitor, fulvestrant, to shed light on both common and distinct activities between SRC-3 and ERα inhibition. Bearing in mind the key role of SRC-3 in tumorigenesis of other types of cancer, we extended our study by validating potential hits identified from the MCF-7 screen in other cancer cell lines.

Targeted nanomedicine modalities for prostate cancer treatment

Prostate cancer (PC) is the second most common cause of death amongst men in the USA. Therapy of PC has been transformed in the past decade by introducing novel therapeutics, advanced functional imaging and diagnostic approaches, next generation sequencing, as well as improved application of existing therapies in localized PC. Treatment of PC at the different stages of the disease may include surgery, androgen deprivation therapy (ADT), chemotherapy and radiation therapy. However, although ADT has proven efficacious in PC treatment, its effectiveness may be temporary, as these tumors frequently develop molecular mechanisms of therapy resistance, which allow them to survive and proliferate even under conditions of testosterone deprivation, inhibition of androgen receptor signaling, or cytotoxic drug treatment. Importantly, ADT was found to induce key alterations which frequently result in the formation of metastatic tumors displaying a therapy refractory phenotype. Hence, to overcome these serious therapeutic impediments, novel PC cell-targeted therapeutic strategies are being developed. These include diverse platforms enabling specific enhanced antitumor drug uptake and increased intracellular accumulation. Studies have shown that these novel treatment modalities lead to enhanced antitumor activity and diminished systemic toxicity due to the use of selective targeting and decreased drug doses. The underlying mechanism of targeting and internalization is based upon the interaction between a selective ligand, conjugated to a drug-loaded nanoparticle or directly to an anti-cancer drug, and a specific plasma membrane biomarker, uniquely overexpressed on the surface of PC cells. Another targeted therapeutic approach is the delivery of unique anti-oncogenic signaling pathway-based therapeutic drugs, which are selectively cytotoxic to PC cells. The current paper reviews PC targeted modalities reported in the past 6 years, and discusses both the advantages and limitations of the various targeted treatment strategies.

Exploring Metabolic Adaptations to the Acidic Microenvironment of Osteosarcoma Cells Unveils Sphingosine 1-Phosphate as a Valuable Therapeutic Target

Simple Summary

By studying the role of tumor acidosis in osteosarcoma, we have identified a novel lipid signaling pathway that is selectively activated in acid-induced highly metastatic cell subpopulation. Furthermore, when combined to low-serine/glycine diet, the targeting of this acid-induced lipid pathway by the FDA-approved drug FTY720 significantly impaired tumor growth. This new knowledge will provide a giant leap in the understanding of the molecular mechanisms responsible for sarcoma relapses and metastasis. Finally, we paved the way to the recognition of a novel biomarker, as our data provided evidence of significantly high circulating levels in the serum of osteosarcoma patients of S1P, a lipid member of the identified acid-driven metabolic pathway.

Abstract

Acidity is a key player in cancer progression, modelling a microenvironment that prevents immune surveillance and enhances invasiveness, survival, and drug resistance. Here, we demonstrated in spheroids from osteosarcoma cell lines that the exposure to acidosis remarkably caused intracellular lipid droplets accumulation. Lipid accumulation was also detected in sarcoma tissues in close proximity to tumor area that express the acid-related biomarker LAMP2. Acid-induced lipid droplets-accumulation was not functional to a higher energetic request, but rather to cell survival. As a mechanism, we found increased levels of sphingomyelin and secretion of the sphingosine 1-phosphate, and the activation of the associated sphingolipid pathway and the non-canonical NF-ĸB pathway, respectively. Moreover, decreasing sphingosine 1-phosphate levels (S1P) by FTY720 (Fingolimod) impaired acid-induced tumor survival and migration. As a confirmation of the role of S1P in osteosarcoma, we found S1P high circulating levels (30.8 ± 2.5 nmol/mL, n = 17) in the serum of patients. Finally, when we treated osteosarcoma xenografts with FTY720 combined with low-serine/glycine diet, both lipid accumulation (as measured by magnetic resonance imaging) and tumor growth were greatly inhibited. For the first time, this study profiles the lipidomic rearrangement of sarcomas under acidic conditions, suggesting the use of anti-S1P strategies in combination with standard chemotherapy.

Repurposing existing drugs for the treatment of COVID-19/SARS-CoV-2 infection: A review describing drug mechanisms of action

The outbreak of a novel coronavirus (SARS-CoV-2) has caused a major public health concern across the globe. SARS-CoV-2 is the seventh coronavirus that is known to cause human disease. As of September 2020, SARS-CoV-2 has been reported in 213 countries and more than 31 million cases have been confirmed, with an estimated mortality rate of ∼3%. Unfortunately, a drug or vaccine is yet to be discovered to treat COVID-19. Thus, repurposing of existing cancer drugs will be a novel approach in treating COVID-19 patients. These drugs target viral replication cycle, viral entry and translocation to the nucleus. Some can enhance innate antiviral immune response as well. Hence this review focuses on comprehensive list of 22 drugs that work against COVID-19 infection. These drugs include fingolimod, colchicine, N4-hydroxycytidine, remdesivir, methylprednisone, oseltamivir, icatibant, perphanizine, viracept, emetine, homoharringtonine, aloxistatin, ribavirin, valrubicin, famotidine, almitrine, amprenavir, hesperidin, biorobin, cromolyn sodium, and antibodies- tocilzumab and sarilumab. Also, we provide a list of 31 drugs that are predicted to function against SARS-CoV-2 infection. In summary, we provide succinct overview of various therapeutic modalities. Among these 53 drugs, based on various clinical trials and literature, remdesivir, nelfinavir, methylpredinosolone, colchicine, famotidine and emetine may be used for COVID-19. SIGNIFICANCE: It is of utmost important priority to develop novel therapies for COVID-19. Since the effect of SARS-CoV-2 is so severe, slowing the spread of diseases will help the health care system, especially the number of visits to Intensive Care Unit (ICU) of any country. Several clinical trials are in works around the globe. Moreover, NCI developed a recent and robust response to COVID-19 pandemic. One of the NCI's goals is to screen cancer related drugs for identification of new therapies for COVID-19. https://www.cancer.gov/news-events/cancer-currents-blog/2020/covid-19-cancer-nci-response?cid=eb_govdel.

Sphingosine Kinase 1 Signaling in Breast Cancer: A Potential Target to Tackle Breast Cancer Stem Cells

Sphingosine kinases (SPHKs) are conserved lipid enzymes that catalyze the formation of sphingosine-1-phosphate (S1P) through ATP-dependent phosphorylation of sphingosine. Two distinct SPHK isoforms, namely SPHK1 and SPHK2, have been identified to date, and the former has been implicated for its oncogenic roles in cancer development and progression. While SPHK1 signaling axis has been extensively studied in non-stem breast cancer cells, recent evidence has emerged to suggest a role of SPHK1 in regulating cancer stem cells (CSCs). With the clinical implications of CSCs in disease relapse and metastasis, it is believed that therapeutic approaches that can eradicate both non-stem cancer cells and CSCs could be a key to cancer cure. In this review, we first explore the oncogenic functions of sphingosine kinase 1 in human cancers and summarize current research findings of SPHK1 signaling with a focus on breast cancer. We also discuss the therapeutic potentials and perspectives of targeting SPHK1 signaling in breast cancer and cancer stem cells. We aim to offer new insights and inspire future studies looking further into the regulatory functions of SPHK1 in CSC-driven tumorigenesis, uncovering novel therapeutic avenues of using SPHK1-targeted therapy in the treatment of CSC-enriched refractory cancers.

The Tumorigenic Effect of Sphingosine Kinase 1 and Its Potential Therapeutic Target

Sphingosine kinase 1 (SPHK1) regulates cell proliferation and survival by converting sphingosine to the signaling mediator sphingosine 1-phosphate (S1P). SPHK1 is widely overexpressed in most cancers, promoting tumor progression and is associated with clinical prognosis. Numerous studies have explored SPHK1 as a promising target for cancer therapy. However, due to insufficient knowledge of SPHK1 oncogenic mechanisms, its inhibitors’ therapeutic potential in preventing and treating cancer still needs further investigation. In this review, we summarized the metabolic balance regulated by the SPHK1/S1P signaling pathway and highlighted the oncogenic mechanisms of SPHK1 via the upregulation of autophagy, proliferation, and survival, migration, angiogenesis and inflammation, and inhibition of apoptosis. Drug candidates targeting SPHK1 were also discussed at the end. This review provides new insights into the oncogenic effect of SPHK1 and sheds light on the future direction for targeting SPHK1 as cancer therapy.

Resistance and Overcoming Resistance in Breast Cancer

The incidence and mortality of breast cancer (BC) have increased in recent years, and BC is the main cause of cancer-related death in women worldwide. One of the most significant clinical problems in the treatment of patients with BC is the development of therapeutic resistance. Therefore, elucidating the molecular mechanisms involved in drug resistance is critical. The therapeutic decision for the management of patients with BC is based not only on the assessment of prognostic factors but also on the evaluation of clinical and pathological parameters. Although this has been a successful approach, some patients relapse and/or eventually develop resistance to treatment. This review is focused on recent studies on the possible biological and molecular mechanisms involved in both response and resistance to treatment in BC. Additionally, emerging treatments that seek to overcome resistance and reduce side effects are also described. A greater understanding of the mechanisms of action of treatments used in BC might contribute not only to the enhancement of our understanding of the mechanisms involved in the development of resistance but also to the optimization of the existing treatment regimens.

Cis-acting lnc-eRNA SEELA directly binds histone H4 to promote histone recognition and leukemia progression

Background

Long noncoding enhancer RNAs (lnc-eRNAs) are a subset of stable eRNAs identified from annotated lncRNAs. They might act as enhancer activity-related therapeutic targets in cancer. However, the underlying mechanism of epigenetic activation and their function in cancer initiation and progression remain largely unknown.

Results

We identify a set of lncRNAs as lnc-eRNAs according to the epigenetic signatures of enhancers. We show that these lnc-eRNAs are broadly activated in MLL-rearranged leukemia (MLL leukemia), an aggressive leukemia caused by a chromosomal translocation, through a mechanism by which the HOXA cluster initiates enhancer activity, and the epigenetic reader BRD4 cooperates with the coregulator MLL fusion oncoprotein to induce transcriptional activation. To demonstrate the functional roles of lnc-eRNAs, two newly identified lnc-eRNAs transcribed from the SEELA eRNA cluster (SEELA), SEELA1 and SEELA2, are chosen for further studies. The results show that SEELA mediated cis-activated transcription of the nearby oncogene Serine incorporate 2 (SERINC2) by directly binding to the K31 amino acid (aa) of histone H4. Chromatin-bound SEELA strengthens the interaction between chromatin and histone modifiers to promote histone recognition and oncogene transcription. Further studies show that the SEELA-SERINC2 axis regulated aspects of cancer metabolism, such as sphingolipid synthesis, to affect leukemia progression.

Conclusions

This study shows that lnc-eRNAs are epigenetically activated by cancer-initiating oncoproteins and uncovers a cis-activating mechanism of oncogene transcription control based on lnc-eRNA-mediated epigenetic regulation of enhancer activity, providing insights into the critical roles of lnc-eRNAs in cancer initiation and progression.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13059-020-02186-x.

Therapeutic potential of Fingolimod in triple negative breast cancer preclinical models

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Fingolimod represses triple negative breast cancer cells survival in vitro by inducing cell apoptosis.

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Fingolimod represses triple negative breast cancer progression in orthotopic graft murine in vivo models.

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Fingolimod represses spleen and liver metastases without affecting lung metastasis in murine in vivo models.

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In contrast with Cisplatin, Fingolimod is well tolerated in murine in vivo models.

Surgery followed by a chemotherapy agent is the first-line treatment for breast cancer patients. Nevertheless, new targets are required for women with triple-negative breast cancer (TNBC) in order to improve the treatment of this aggressive cancer subtype. Multiple pro-inflammatory molecules including lipid-based substances such as sphingosine-1-phosphate (S1P) promote cancer progression. In this preclinical study, we aim to investigate the efficacy of Fingolimod, an inhibitor of S1P / S1P receptors axis, already approved as an immunomodulator in multiple sclerosis.

The impact of Fingolimod was analyzed using in vitro 2D and 3D cell survival analysis and in vivo orthotopic graft models, using mouse and human TNBC cells implanted in immunocompetent or immunodeficient mice, respectively. Resection of the tumor primary mass was also performed to mimic the clinical standard of care.

We demonstrated that Fingolimod repressed tumor cell survival in vitro. We also showed in preclinical mouse TNBC models that Fingolimod repressed tumor progression and liver and spleen metastases without apparent adverse effects on the animals. Our data indicate that Fingolimod induces tumor cells apoptosis and thereby represses tumor progression.

Globally, our data suggest that Fingolimod merits further evaluation as a potential therapeutic opportunity for TNBC.