Comprehensive gene and microRNA expression profiling reveals a role for miRNAs in the oncogenic roles of SphK1 in papillary thyroid cancer

Integrative roles of sphingosine kinase in liver pathophysiology

Bioactive sphingolipids and enzymes that metabolize sphingolipid-related substances have been considered as critical messengers in various signaling pathways. One such enzyme is the crucial lipid kinase, sphingosine kinase (SphK), which mediates the conversion of sphingosine to the potent signaling substance, sphingosine-1-phosphate. Several studies have demonstrated that SphK metabolism is strictly regulated to maintain the homeostatic balance of cells. Here, we summarize the role of SphK in the course of liver disease and illustrate its effects on both physiological and pathological conditions of the liver. SphK has been implicated in a variety of liver diseases, such as steatosis, liver fibrosis, hepatocellular carcinoma, and hepatic failure. This study may advance the understanding of the cellular and molecular foundations of liver disease and establish therapeutic approaches via SphK modulation.

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.

Circulating Exosomal miR-144-3p from Crohn’s Disease Patients Inhibits Human Umbilical Vein Endothelial Cell Function by Targeting FN1

Background

Crohn's disease (CD) is a chronic nonspecific inflammatory disease with unknown pathogenesis and vascular changes associated with the progression of CD. Many studies have shown that miRNAs participate in the development of CD. However, the effect of miRNAs in circulating exosomes on vascular endothelial cells in CD has not been investigated. Our study is aimed at identifying the differential miRNAs in circulating exosomes in CD and exploring their potential roles in human umbilical vein endothelial cells (HUVECs).

Methods

In our study, exosomes were extracted from circulating blood to identify differential miRNAs. After in vitro transfection of HUVECs with miR-144-3p mimics and inhibitors and the corresponding controls, cell counting kit-8, wound healing, Transwell migration, and tube formation assays were performed to study the viability, migration, and angiogenesis of HUVECs. Furthermore, bioinformatics analysis was used to predict miRNA targets. Western blotting was used to determine protein expression. In addition, exogenous supplementation with the fibronectin 1 (FN1) protein rescued the effects of miR-144-3p on changes in cell function in vitro.

Results

miR-144-3p was significantly increased in circulating exosomes of patients with CD compared with those in the control group. The promotion or inhibition of miR-144-3p correspondingly abolished or accelerated cell viability, migration, and angiogenesis. FN1 is a significant target of miR-144-3p, and exogenous FN1 administration improved the function of HUVECs in vitro.

Conclusions

Circulating exosomal miR-144-3p from patients with active CD contributes to vascular endothelial dysfunction by affecting the gene expression of FN1. These findings suggested that circulating exosomal miR-144-3p could be a potential biological marker for CD.

MicroRNAs in Papillary Thyroid Cancer: What Is New in Diagnosis and Treatment

Introduction

Papillary thyroid cancer (PTC) accounts for up to 80% of thyroid malignancies. New diagnostic and therapeutic options are suggested including innovative molecular methods. MicroRNAs (miRNAs) are nonprotein coding single-stranded RNAs that regulate many cell processes. The aim of the present study is to review the deregulated miRNAs associated with PTCs.

Methods

A bibliographic research was conducted, resulting in 272 articles referred to miRNAs and PTC. Regarding our exclusion criteria, 183 articles were finally included in our review.

Results

A remarkably large number of miRNAs have been found to be deregulated during PTC manifestation in the literature. The deregulated miRNAs are detected in tissue samples, serum/plasma, and FNA samples of patients with PTC. These miRNAs are related to several molecular pathways, involving genes and proteins responsible for important biological processes. MiRNA deregulation is associated with tumor aggressiveness, including larger tumor size, multifocality, extrathyroidal extension, lymphovascular invasion, lymph node and distant metastasis, and advanced tumor node metastasis stage.

Conclusion

MiRNAs are proposed as new diagnostic and therapeutic tools regarding PTC. They could be essential biomarkers for PTC diagnosis applied in serum and FNA samples, while their contribution to prognosis is of great importance.

Interaction of microRNAs with sphingosine kinases, sphingosine-1 phosphate, and sphingosine-1 phosphate receptors in cancer

Sphingosine-1-phosphate (S1P), a pleiotropic lipid mediator, participates in various cellular processes during tumorigenesis, including cell proliferation, survival, drug resistance, metastasis, and angiogenesis. S1P is formed by two sphingosine kinases (SphKs), SphK1 and SphK2. The intracellularly produced S1P is delivered to the extracellular space by ATP-binding cassette (ABC) transporters and spinster homolog 2 (SPNS2), where it binds to five transmembrane G protein-coupled receptors to mediate its oncogenic functions (S1PR1-S1PR5). MicroRNAs (miRNAs) are small non-coding RNAs, 21-25 nucleotides in length, that play numerous crucial roles in cancer, such as tumor initiation, progression, apoptosis, metastasis, and angiogenesis via binding to the 3'-untranslated region (3'-UTR) of the target mRNA. There is growing evidence that various miRNAs modulate tumorigenesis by regulating the expression of SphKs, and S1P receptors. We have reviewed various roles of miRNAs, SphKs, S1P, and S1P receptors (S1PRs) in malignancies and how notable miRNAs like miR-101, miR-125b, miR-128, and miR-506, miR-1246, miR-21, miR-126, miR499a, miR20a-5p, miR-140-5p, miR-224, miR-137, miR-183-5p, miR-194, miR181b, miR136, and miR-675-3p, modulate S1P signaling. These tumorigenesis modulating miRNAs are involved in different cancers including breast, gastric, hepatocellular carcinoma, prostate, colorectal, cervical, ovarian, and lung cancer via cell proliferation, invasion, angiogenesis, apoptosis, metastasis, immune evasion, chemoresistance, and chemosensitivity. Therefore, understanding the interaction of SphKs, S1P, and S1P receptors with miRNAs in human malignancies will lead to better insights for miRNA-based cancer therapy.

Epigenetic signature associated with thyroid cancer progression and metastasis

Thyroid cancer is not among the top cancers in terms of diagnosis or mortality but it still ranks fifth among the cancers diagnosed in women. Infact, women are more likely to be diagnosed with thyroid cancer than the males. The burden of thyroid cancer has dramatically increased in last two decades in China and, in the United States, it is the most diagnosed cancer in young adults under the age of twenty-nine. All these factors make it worthwhile to fully understand the pathogenesis of thyroid cancer. Towards this end, microRNAs (miRNAs) have constantly emerged as the non-coding RNAs of interest in various thyroid cancer subtypes on which there have been numerous investigations over the last decade and half. This comprehensive review takes a look at the current knowledge on the topic with cataloging of miRNAs known so far, particularly related to their utility as epigenetic signatures of thyroid cancer progression and metastasis. Such information could be of immense use for the eventual development of miRNAs as therapeutic targets or even therapeutic agents for thyroid cancer therapy.

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.

Relationship between Sphk1/S1P and microRNAs in human cancers

Sphingosine kinases type 1 (SphK1) is a key enzyme in the phosphorylation of sphingosine to sphingosine 1-phosphate (S1P). Different abnormalities in SphK1 functions may correspond with poor prognosis in various cancers. Additionally, upregulated SphK1/S1P could promote cancer cell proliferation, angiogenesis, mobility, invasion, and metastasis. MicroRNAs as conserved small noncoding RNAs play major roles in cancer initiation, progression, metastasis, etc. Their posttranscriptionally mechanisms could affect the development of cancer growth or tumorigenesis suppression. The growing number of studies has described that various microRNAs can be regulated by SphK1, and its expression level can also be regulated by microRNAs. In this review, the relationship of SphK1 and microRNA functions and their interaction in human malignancies have been discussed. Based on them novel treatment strategies can be introduced.

Regulatory effect of miR-144-3p on the function of human trabecular meshwork cells and fibronectin-1

Role of microRNA (miR)-144-3p in regulating the function of human trabecular meshwork cells (HTMCs) and fibronectin-1 (FN-1) was investigated. HTM cell lines were divided into five groups, of which four groups established oxidative stress HTMC models and one served as a control group. The four model groups were transfected with miR-144-3p independent sequence, inhibitory sequence, over-expression sequence, and the blank group received no transfection. In addition, 40 primary open angle glaucoma patients treated in Xuzhou No. 1 People's Hospital were included in the observation group, and 40 healthy individuals were enrolled as a normal group. RT-qPCR was used for the detection of miR-144-3p expression in serum and cells of patients and healthy people in each group, western blot analysis for FN-1 expression in cells, CCK-8 kit for cell proliferation, and Transwell for cell invasion. The expression of serum miR-144-3p in the observation group was significantly lower than that in the normal group (P<0.05). The cell optical density value in the over-expression group was significantly higher than that in the other groups (P<0.05), and in the inhibition group was significantly lower than that in the other groups (P<0.05). The number of cell-penetration in the over-expression group was significantly higher than that in the other groups (P<0.05). The expression of FN-1 protein in the over-expression group was significantly lower than that in the other four groups (P<0.05), and the expression in the inhibition group was significantly higher than that in the other four groups (P<0.05). The over-expression of miR-144-3p promotes proliferation and invasion of HTMCs by inhibiting the expression of FN-1 in inoxidative stress HTMCs, and is a potential target for glaucoma treatment.

New insights into the roles and regulation of SphK2 as a therapeutic target in cancer chemoresistance

Chemoresistance is a complicated process developed by most cancers and accounts for the majority of relapse and metastasis in cancer. The main mechanisms of chemoresistance phenotype include increased expression and/or activated drug efflux pumps, altered DNA repair, altered metabolism of therapeutics as well as impaired apoptotic signaling pathways. Aberrant sphingolipid signaling has also recently received considerable attention in chemoresistance. Sphingolipid metabolites regulate main biological processes such as apoptosis, cell survival, proliferation, and differentiation. Two sphingosine kinases, SphK1 and SphK2, convert sphingosine to sphingosine-1-phosphate, an antiapoptotic bioactive lipid mediator. Numerous evidence has revealed the involvement of activated SphK1 in tumorigenesis and resistance, however, contradictory results have been found for the role of SphK2 in these functions. In some studies, overexpression of SphK2 suppressed cell growth and induced apoptosis. In contrast, some others have shown cell proliferation and tumor promotion effect for SphK2. Our understanding of the role of SphK2 in cancer does not have a sufficient integrity. The main focus of this review will be on the re-evaluation of the role of SphK2 in cell death and chemoresistance in light of our new understanding of molecular targeted therapy. We will also highlight the connections between SphK2 and the DNA damage response. Finally, we will provide our insight into the regulatory mechanisms of SphKs by two main categories, micro and long, noncoding RNAs as the novel players of cancer chemoresistance.

The sphingosine kinase-1/sphingosine-1-phosphate axis in cancer: Potential target for anticancer therapy

Sphingolipid metabolites, such as ceramide, sphingosine and sphingosine-1-phosphate (S1P), play many important roles in cellular activities. Ceramide and sphingosine inhibit cell proliferation and induce cell apoptosis while S1P has the opposite effect. Maintaining a metabolic balance of sphingolipids is essential for growth and development of cells. Sphingosine kinase (SPHK) is an important regulator for keeping this balance. It controls the level of S1P and plays important roles in proliferation, migration, and invasion of cancer cells and tumor angiogenesis. There are two isoenzymes of sphingosine kinase, SPHK1 and SPHK2. SPHK1 is ubiquitously expressed in most cancers where it promotes survival and proliferation, while SPHK2 is restricted to only certain tissues and its functions are not well characterized. SPHK1 is currently considered as a novel target for the treatment of cancers. Targeting SPHK1 would provide new strategies for cancer treatment and improve the prognosis of cancer patients. Here we review and summarize the current research findings on the SPHK1-S1P axis in cancer from many aspects including structure, expression, regulation, mechanism, and potential inhibitors.

SPHK1 promotes metastasis of thyroid carcinoma through activation of the S1P/S1PR3/Notch signaling pathway

Thyroid carcinoma is characterized by an aggressive behavior, lack of effective targeted therapies and a high rate of relapse. Sphingosine kinase 1 (SPHK1) has been reported to be a critical regulatory factor in the progression of thyroid carcinoma, but the correlation between SPHK1 and clinical prognosis of patients with thyroid carcinoma has remained to be fully elucidated. The present study aimed to systematically assess the roles of SPHK1 in thyroid carcinoma metastasis and further investigate the possible underlying mechanisms. First, the expression of SPHK1 was detected in tissue samples from 53 thyroid carcinoma patients and in thyroid carcinoma cell lines by reverse transcription-quantitative polymerase chain reaction analysis. Furthermore, the level of phospho-(p)-SPHK1 was immunohistochemically detected in human thyroid carcinoma tissue samples. The activity of SPHK1 was measured with a commercial SPHK1 Activity Assay kit. A sphingosine-1-phosphate (S1P) competitive ELISA kit was used to determine the extracellular S1P levels. The metastatic potential was assessed by a Transwell assay. In addition, the association between SPHK1 and clinicopathological features of the patients was analyzed. The results indicated that the expression of SPHK1 in thyroid carcinoma samples was significantly higher than in paired adjacent normal thyroid tissues. High levels of SPHK1 were positively correlated with poor overall survival and progression-free survival. Downregulation of SPHK1 by lentiviral vector expressing SPHK1 small interfering (si)RNA evidently repressed Notch signaling and reduced the migration and invasion of thyroid carcinoma cells in vitro and in a NOD/SCID mouse model. Furthermore, inhibition of SPHK1 by siRNA or treatment with SPHK1 inhibitor 5C sensitized thyroid carcinoma to cisplatin and doxorubicin. In addition, it was demonstrated that silencing of SPHK1 effectively inhibits processes associated with thyroid carcinoma metastasis through the Notch signaling pathway, and SPHK1 may therefore represent a potential therapeutic target in thyroid carcinoma. In conclusion, the present study indicated that high levels of p-SPHK1 were positively correlated with high levels of S1P which in turn promoted thyroid carcinoma metastasis via the S1P/S1P receptor 3/Notch signaling pathway, suggesting possible prognostic markers and therapeutic targets.