Influence of sphingolipid enzymes on blood glucose levels, development of diabetes, and involvement of pericytes.

AIMS: Sulfatide is a chaperone for insulin manufacturing in beta cells. Here we explore whether the blood glucose values normally could be associated with this sphingolipid and especially two of its building enzymes CERS2 and CERS6. Both T1D and T2D have low blood sulfatide levels, and insulin resistance on beta cells at clinical diagnosis. Furthermore, we examined islet pericytes for sulfatide, and beta-cell receptors for GLP-1, both of which are related to the insulin production. MATERIALS AND METHODS: We examined mRNA levels in islets from the DiViD and nPOD studies, performed genetic association analyses, and histologically investigated pericytes in the islets for sulfatide. RESULTS: Polymorphisms of the gene encoding the CERS6 enzyme responsible for synthesising dihydroceramide, a precursor to sulfatide, are associated with random blood glucose values in non-diabetic persons. This fits well with our finding of sulfatide in pericytes in the islets, which regulates the capillary blood flow in the islets of Langerhans, which is important for oxygen supply to insulin production. In the islets of newly diagnosed T1D patients, we observed low levels of GLP-1 receptors; this may explain the insulin resistance in their beta cells and their low insulin production. In T2D patients, we identified associated polymorphisms in both CERS2 and CERS6. CONCLUSIONS: Here, we describe several polymorphisms in sulfatide enzymes related to blood glucose levels and HbA1c in non-diabetic individuals. Islet pericytes from such persons contain sulfatide. Furthermore, low insulin secretion in newly diagnosed T1D may be explained by beta-cell insulin resistance due to low levels of GLP-1 receptors.

lncRNA CERS6-AS1 upregulates the expression of ANLN by sponging miR-424-5p to promote the progression and drug resistance of lung adenocarcinoma.

Long non-coding RNAs (lncRNAs) play a crucial role in tumor generation and progression. However, the exact functional significance and underlying molecular mechanism by which lncRNA CERS6-AS1 operates in the context of lung adenocarcinoma (LUAD) remain unknown. We aimed to evaluate the potential role of the CERS6-AS1/miR-424-5p/ANLN axis in the progression of LUAD through bioinformatics and cytobehavioral experiments, and to provide a new insight into the combined treatment of LUAD. Based on the TCGA database, the expression of CERS6-AS1 in pan-cancer was evaluated, and its prognostic performance in LUAD was evaluated by ROC curve, survival curve and COX analysis. In addition, quantification of CERS6-AS1 expression levels in LUAD patients and lung cancer cells using quantitative real-time polymerase chain reaction (RT-qPCR), and further validate the functional significance of CERS6-AS1 in promoting the proliferation, migration, and invasion abilities of lung cancer cells. The competitive endogenous RNA (ceRNA) network was constructed, and miR-424-5p inhibitors were applied to CERS6-AS1 knockdown cells. The potential downstream genes associated with the regulatory axis of CERS6-AS1/miR-424-5p were analyzed by PPI network and gene enrichment analysis (KEGG). Finally, we evaluated the prognostic value of high expression of ANLN in LUAD and its effects on immune cell infiltration, tumor mutation burden, chemotherapy response, and immunotherapy. CERS6-AS1 expression was significantly elevated in both LUAD patients and lung cancer cells. In the CERS6-AS1 knockdown assay, the proliferation, invasion, migration and epithelial-mesenchymal transformation (EMT) of cancer cells were significantly inhibited. Notably, there was a prominent upregulation of miR-424-5p expression in cells where CERS6-AS1 was knocked down. Co-transfection of siRNA and miR-424-5p inhibitors into lung cancer cells restored the restriction on lung cancer cells. Anillin (ANLN) has been identified as a potential target gene for miR-424-5p and as a prognostic and immune biomarker associated with immune cell infiltration and tumor mutational burden in LUAD. Additionally, ANLN impacts the efficacy of chemotherapy and immunotherapy in LUAD patients. This study reveals a novel regulatory mechanism in which CERS6-AS1 may contribute to the progression of LUAD by influencing the expression of ANLN as a competitive sponge for miR-424-5p.

Ceramide synthase 6 (CerS6) is upregulated in alcohol-associated liver disease and exhibits sex-based differences in the regulation of energy homeostasis and lipid droplet accumulation.

OBJECTIVE: Alcohol-associated liver disease (ALD) is the leading cause of liver-related mortality worldwide. Current strategies to manage ALD focus largely on advanced stage disease, however, metabolic changes such as glucose intolerance are apparent at the earliest stage of alcoholic steatosis and increase the risk of disease progression. Ceramides impair insulin signaling and accumulate in ALD, and metabolic pathways involving ceramide synthase 6 (CerS6) are perturbed in ALD during hepatic steatosis. In this study, we aimed to investigate the role of CerS6 in ALD development and the relevance of CerS6 to human ALD. METHODS: C57BL/6 WT and CerS6 KO mice of both sexes were fed either a Lieber-DeCarli control (CON) or 15% ethanol (EtOH) diet for six weeks. In vivo metabolic tests including glucose and insulin tolerance tests (GTT and ITT) and energy expenditure were performed. The mice were euthanized, and serum and liver lipids and liver histology were examined. For in vitro studies, CerS6 was deleted in human hepatocytes, VL17A and cells were incubated with EtOH and/or C16:0-ceramides. RNAseq analysis was performed in livers from mice and human patients with different stages of ALD and diseased controls. RESULTS: After six weeks on an EtOH diet, CerS6 KO mice had reduced body weight, food intake, and %fat mass compared to WT mice. Energy expenditure increased in both male and female KO mice, however, was only statistically significant in male mice. In response to EtOH, WT mice developed mild hepatic steatosis, while steatosis was ameliorated in KO mice as determined by H&E and ORO staining. KO mice showed significantly decreased long-chain ceramide species, especially C16:0-ceramides, in the serum and liver tissues compared to WT mice. CerS6 deletion decreased serum TG and NEFA only in male not female mice. CerS6 deletion improved glucose tolerance and insulin resistance in EtOH-fed mice of both sexes. RNAseq analysis revealed that 74 genes are significantly upregulated and 66 genes are downregulated by CerS6 deletion in EtOH-fed male mice, with key network pathways including TG biosynthetic process, positive regulation of lipid localization, and fat cell differentiation. Similar to RNAseq results, absence of CerS6 significantly decreased mRNA expression of lipid droplet associated proteins in EtOH-fed mice. In vitro, EtOH stimulation significantly increased PLIN2 protein expression in VL17A cells while CerS6 deletion inhibited EtOH-mediated PLIN2 upregulation. C16:0-ceramide treatment significantly increased PLIN2 protein expression compared to CON. Notably, progression of ALD in humans was associated with increased hepatic CerS6 expression. CONCLUSIONS: Our findings demonstrate that CerS6 deletion improves glucose homeostasis in alcohol-fed mice and exhibits sex-based differences in the attenuation of EtOH-induced weight gain and hepatic steatosis. Additionally, we unveil that CerS6 plays a major role as a regulator of lipid droplet biogenesis in alcohol-induced intra-hepatic lipid droplet formation, identifying it as a putative target for early ALD management.

LASP1, CERS6, and Actin Form a Ternary Complex That Promotes Cancer Cell Migration.

CERS6 is associated with metastasis and poor prognosis in non-small cell lung cancer (NSCLC) patients through d18:1/C16:0 ceramide (C16 ceramide)-mediated cell migration, though the detailed mechanism has not been elucidated. In the present study, examinations including co-immunoprecipitation, liquid chromatography, and tandem mass spectrometry analysis were performed to identify a novel binding partner of CERS6. Among the examined candidates, LASP1 was a top-ranked binding partner, with the LIM domain possibly required for direct interaction. In accord with those findings, CERS6 and LASP1 were found to co-localize on lamellipodia in several lung cancer cell lines. Furthermore, silencing of CERS6 and/or LASP1 significantly suppressed cell migration and lamellipodia formation, whereas ectopic addition of C16 ceramide partially rescued those phenotypes. Both LASP1 and CERS6 showed co-immunoprecipitation with actin, with those interactions markedly reduced when the LASP1-CERS6 complex was abolished. Based on these findings, it is proposed that LASP1-CERS6 interaction promotes cancer cell migration.

LncRNA CERS6-AS1 Is a Tumor Promoter in Cervical Cancer by Sponging miR-195-5p.

OBJECTIVE: CERS6 antisense RNA 1 (CERS6-AS1), a long non-coding RNA (lncRNA), plays a role in the malignant progression of a variety of cancers. However, it is unclear whether it affects the malignant behavior of cervical cancer (CC) cells. METHODS: CERS6-AS1 and miR-195-5p expression was estimated in CC via qRT-PCR. CCK-8, caspase-3 activity, scratch, and Transwell assays were performed to detect CC cell viability, caspase-3 activity, migration, and invasion in vitro. A tumor xenograft experiment was designed to study the growth of CC tumors in vivo. RIP and luciferase reporter experiments verified the relationship between CERS6-AS1 and miR-195-5p. RESULTS: CERS6-AS1 overexpression and poor miR-195-5p levels were observed in CC. Inhibition of CERS6-AS1 impaired the viability, invasion, and migration of CC cells, promoted apoptosis, and suppressed tumor growth. In terms of the underlying mechanism, CERS6-AS1, as a competitive endogenous RNA (ceRNA), participated in the regulation of miR-195-5p levels in CC cells. Functionally, miR-195-5p interference attenuated the inhibitory effect of CERS6-AS1 on the malignant behaviors of CC cells. CONCLUSION: CERS6-AS1 acts as an oncogene in CC, in vivo and in vitro, by negatively regulating miR-195-5p.

CERS6 antisense RNA 1 promotes colon cancer via upregulating mitochondrial calcium uniporter.

BACKGROUND: Colon cancer (CC) belongs to a common cancer of digestive system. Long non-coding RNAs (lncRNAs) are dysregulated in numerous cancers and affect their development. The function of lncRNA CERS6 antisense RNA 1 (CERS6-AS1) in CC remains unclear. MATERIALS AND METHODS: CERS6-AS1 expression in colon adenocarcinoma tissues and CC cell lines was assessed by The Cancer Genome Atlas database and quantitative real-time polymerase chain reaction analysis. The function of CERS6-AS1 in CC was analysed by 5-ethynyl-2'-deoxyuridine, colony formation, flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labelling, wound healing, Transwell and immunofluorescence assays. Mechanistic analyses including RNA pull down, RNA-binding protein immunoprecipitation and luciferase reporter assay revealed the interaction between RNAs. RESULTS: CERS6-AS1 expression was aberrantly upregulated in colon adenocarcinoma tissues and CC cell lines. CERS6-AS1 knockdown inhibited CC cell malignant phenotypes and in vivo tumour growth. CERS6-AS1 served as the competing endogenous RNA of microRNA-16-5p in CC, and microRNA-16-5p inhibition partly rescued the effects of CERS6-AS1 depletion on CC development. Mitochondrial calcium uniporter was targeted by microRNA-16-5p. Mitochondrial calcium uniporter upregulation completely remedied the influence of CERS6-AS1 silencing in CC progression. Moreover, CERS6-AS1 enhanced the stability of mitochondrial calcium uniporter messenger RNA via recruiting RNA-binding protein embryonic lethal abnormal vision like 1. CONCLUSION: CERS6-AS1 promotes the development of CC via upregulating mitochondrial calcium uniporter expression.

The role of lncRNA CERS6-AS1 in cancer and its molecular mechanisms: A systematic review and meta-analysis.

BACKGROUND: LncRNAs have the potential to play a regulatory role in different processes of cancer development and progression. We conducted a systematic review and meta-analysis of evidence on the clinical significance and prognostic value of lncRNA CERS6-AS1 in cancer. METHODS: This systematic review was conducted following PRISMA guidelines. Medline and Embase databases were searched using the relevant key terms covering lncRNA CERS6-AS1 and cancer. We pooled the estimated effect sizes and their 95 % confidence interval (CI) using random-effects models in STATA 16.0 (StataCorp, College Station, TX, USA). RESULTS: Eleven articles on pancreatic, colorectal, gastric, papillary thyroid, breast, and hepatocellular cancers fulfilled our eligibility criteria. Studies consistently found that lncRNA CERS6-AS1 expression is upregulated in all assessed cancers. Based on our meta-analysis, its aberrant expression was directly associated with unfavorable clinical outcomes, including higher stage (pooled Odds ratios (95 % CI): 3.15 (2.01-4.93; I2 = 0.0 %), tumor size (1.97 (1.27-3.05; I2 = 37.8 %), lymph node metastasis (6.48 (4.01-10.45; I2 = 0.40 %), and poor survival (Pooled log-rank test P-value < 0.001) in patients. Regarding potential mechanisms, functional studies revealed that LncRNA CERS6-AS1 is involved in cancer growth mainly by sponging miRNAs and regulating their downstream targets. CONCLUSION: Available evidence suggests that LncRNA CERS6-AS1 is upregulated in different cancers and has an oncogenic role. LncRNA CERS6-AS1 expression level might predict cancer prognosis, highlighting its potential application as a prognostic biomarker for cancer.

IGF2BP3 Worsens Lung Cancer through Modifying Long Non-coding RNA CERS6-AS1/microRNA-1202 Axis.

BACKGROUND: Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) can epigenetically regulate lung cancer progression, but its regulatory mechanism in the disease lacks sufficient exploration. OBJECTIVE: The study was conducted to probe the regulatory function of IGF2BP3 in lung cancer via modulating the long non-coding RNA CERS6-AS1/microRNA-1202 (CERS6- AS1/miR-1202) axis. METHODS: Clinical samples were collected to evaluate IGF2BP3, CERS6-AS1, miR-1202 and glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5) levels. The interactions among IGF2BP3, CERS6-AS1, miR-1202 and GDPD5 were assessed. IGF2BP3-, CERS6-AS1-, and miR-1202-related constructs were transfected into lung cancer cells to determine cell biological functions. Cell tumor formation ability was further detected in vivo. RESULTS: High expression of IGF2BP3, CERS6-AS1 and GDPD5, and low expression of miR-1202 levels were witnessed in lung cancer tissues. Suppression of IGF2BP3 restrained lung cancer progression. IGF2BP3 positively modulated CERS6-AS1 to regulate miR-1202-targeted GDPD5. Inhibition of CERS6-AS1 or promotion of miR-1202 depressed lung cancer aggravation. CERS6-AS1 silencing or miR-1202 overexpression reversed the impacts induced by IGF2BP3 on lung cancer. CONCLUSION: IGF2BP3 facilitates the development of lung cancer cells via binding to the CERS6-AS1 promoter and down-regulating miR-1202, which may be related to GDPD5 upregulation.

Ceramide Synthase 6 Mediates Triple-Negative Breast Cancer Response to Chemotherapy Through RhoA- and EGFR-Mediated Signaling Pathways.

PURPOSE: Limited treatment options and lack of treatment sensitivity biomarkers make the clinical management of triple-negative breast cancer (TNBC) challenging. Ceramide synthase 6 (CERS6) generates ceramides, which are key intermediates in sphingolipid biosynthesis and play important roles in cancer progression and resistance. METHODS: CERS6 was analyzed to determine its potential as a treatment sensitivity biomarker. CERS6 levels were determined in patients with breast cancer, and the roles and downstream signaling of CERS6 were analyzed using cellular and biochemical assays. RESULTS: Analysis of CERS6 expression in 195 patients with TNBC and their clinical response to chemotherapy revealed that individuals with CERS6 overexpression experienced significantly inferior responses to chemotherapy than those without CERS6 overexpression. Functional analysis demonstrated that although CERS6 overexpression did not affect TNBC cell growth and migration, it conferred chemoresistance. CERS6 inhibition significantly reduced growth, migration, and survival by suppressing the RhoA- and EGFR-mediated signaling pathways. Compared to control cells, CERS6-depleted cells were consistently less viable at different concentrations of chemotherapeutic agents. CONCLUSION: Our study is the first to demonstrate that CERS6 may serve as a treatment sensitivity biomarker in patients with TNBC in response to chemotherapy. In addition, our findings suggested that CERS6 may be a therapeutic target for TNBC treatment.

Exercise Promotes Pro-Apoptotic Ceramide Signaling in a Mouse Melanoma Model.

Ceramides are essential sphingolipids that mediate cell death and survival. Low ceramide content in melanoma is one mechanism of drug resistance. Thus, increasing the ceramide content in tumor cells is likely to increase their sensitivity to cytotoxic therapy. Aerobic exercise has been shown to modulate ceramide metabolism in healthy tissue, but the relationship between exercise and ceramide in tumors has not been evaluated. Here, we demonstrate that aerobic exercise causes tumor cell apoptosis and accumulation of pro-apoptotic ceramides in B16F10 but not BP melanoma models using mice. B16F10 tumor-bearing mice were treated with two weeks of moderate treadmill exercise, or were control, unexercised mice. A reverse-phase protein array was used to identify canonical p53 apoptotic signaling as a key pathway upregulated by exercise, and we demonstrate increased apoptosis in tumors from exercised mice. Consistent with this finding, pro-apoptotic C16-ceramide, and the ceramide generating enzyme ceramide synthase 6 (CerS6), were higher in B16F10 tumors from exercised mice, while pro-survival sphingosine kinase 1 (Sphk1) was lower. These data suggest that exercise contributes to B16F10 tumor cell death, possibly by modulating ceramide metabolism toward a pro-apoptotic ceramide/sphingosine-1-phosphate balance. However, these results are not consistent in BP tumors, demonstrating that exercise can have different effects on tumors of different patient or mouse origin with the same diagnosis. This work indicates that exercise might be most effective as a therapeutic adjuvant with therapies that kill tumor cells in a ceramide-dependent manner.

CERS6-AS1 Facilitates Oncogenesis and Restrains Ferroptosis in Papillary Thyroid Carcinoma by Serving as a ceRNA through miR-497-5p/LASP1 Axis.

OBJECTIVE: The purpose of this study was to explore the function and mechanism of LncRNA CERS6-AS1 on papillary thyroid cancer. MATERIALS: CERS6-AS1, miR-497-5p, and LASP1 expression in papillary thyroid cancer tissues and cells were detected by RT-PCR. The relationship between CERS6-AS1 expression and clinical characteristics was analyzed, and overall survival was evaluated via Kaplan-Meier analysis. Cell activity was tested by cell counting kit-8, cell reactive oxygen species was detected by DCFH-DA method, and cell iron ion was detected by iron analysis kit. The relationship among CERS6-AS1, miR-497-5p, and LASP1 was confirmed by luciferase reporter gene detection, RNA pull-down detection, and RIP detection. The expression of related proteins was assessed by western blot or immunohistochemistry. RESULTS: High level of CERS6-AS1 and LASP1 was detected in papillary thyroid cancer tissues and cells and predicted poor prognosis. In contrast, miR-497-5p was decreased in papillary thyroid cancer tissues and cells, which was positively correlated with prognosis. Silencing CERS6-AS1 suppressed cell viability and increased ferroptosis in papillary thyroid cancer. LASP1 was modulated by CERS6-AS1 through sponging miR-497-5p. Up-regulation of LASP1 or silencing miR-497-5p could weaken the effect of CERS6-AS1 on papillary thyroid cancer cells. Silencing CERS6-AS1 restrained the growth of xenografted tumors. CONCLUSION: Our findings demonstrated that down-regulation of CERS6-AS1 reduced cell viability and amplified cell ferroptosis by modulating the miR-497-5p/LASP1 axis in papillary thyroid cancer.

Danhe granule ameliorates nonalcoholic steatohepatitis and fibrosis in rats by inhibiting ceramide de novo synthesis related to CerS6 and CerK.

ETHNOPHARMACOLOGICAL RELEVANCE: Danhe granule (DHG) is used by Chinese doctors to treat blood stasis, phlegm and dampness. Its lipid-lowering ability has been investigated in our previous research. However, the anti-liver inflammatory and fibrotic effects and mechanism of action of DHG in non-alcoholic steatohepatitis (NASH) have not been explored. AIM OF THE STUDY: To evaluate the ameliorative effects of DHG on liver inflammation and fibrosis in a methionine/choline-deficient (MCD) diet-induced NASH rat model, and its underlying mechanism. MATERIALS AND METHODS: Sprague-Dawley rats were fed an MCD diet for two weeks and then treated with or without DHG by oral gavage for eight weeks. Their body weight and liver index were measured. The serum alanine aminotransferase (ALT) and aspartate transaminase (AST) activities as well as the liver triglyceride (TG) and free fatty acid (FFA) levels were tested using reagent kits. Inflammatory cytokines, including Tnf-α, Il-ß and Il-6, and fibrosis genes, including Acta2, Col1a1, Col1a2 and Tgf-ß were examined by real-time quantitative PCR (RT-qPCR). Hematoxylin-eosin (H&E), Oil Red O, Masson's and Sirius Red staining were used to observe liver changes. The plasma and liver ceramide levels were analyzed using HPLC-QQQ-MS/MS. The expression of serine palmitoyl-CoA transferase (Spt), ceramide synthase 6 (Cers6), dihydroceramide desaturase 1 (Des1), glucosylceramide synthase (Gcs), and ceramide kinase (Cerk) mRNA was assayed by RT-qPCR, while the protein expression of CerS6, DES1, GCS, CerK, and casein kinase 2α (CK2α) was tested by western blotting (WB). CerS6 degradation was evaluated using a cycloheximide (CHX) assay in vitro. RESULTS: The liver index decreased by 20% in DHG groups and the serum ALT and AST decreased by approximately 50% and 30%, respectively in the DHG-H group. The liver Oil Red O staining, TG, and FFA changes showed that DHG reduced hepatic lipid accumulation by approximately 30% in NASH rats. H&E, Masson's and Sirius Red staining and the mRNA levels of Tnf-α, Il-ß, Il-6, Acta2, Col1a1, Col1a2 and Tgf-ß revealed that DHG alleviated liver inflammation and fibrosis in NASH rats. The ceramide (Cer 16:0), and hexosylceramide (HexCer 16:0, HexCer 18:0, HexCer 22:0, HexCer 24:0 and HexCer 24:1) levels decreased by approximately 17-56% in the plasma of the DHG-M and H rats. The Cer 16:0 content in the liver decreased by 20%, 50%, and 70% with the DHG-L, M, and H treatments; additionally, the dhCer 16:0, Cer 18:0, HexCer 18:0, HexCer 20:0 Cer 22:0-1P, Cer 24:0-1p, Cer 24:1-1p, and Cer 26:1-1p levels decreased in the DHG groups. The mRNA and protein expression levels of DES1, GCS, Cerk, CerS6, and CHX assay indicated that DHG decreased the mRNA and protein expression levels of CerK and reduced CerS6 protein expression by promoting its degradation. Additionally, DHG attenuated the protein expression of CK2α which could increase CerS6 enzymatic activity by phosphorylating its C-terminal region. CONCLUSION: DHG ameliorated the levels of liver FFA and TG and inflammation and fibrosis in MCD-induced rats, which were associated with decreasing ceramide species in the plasma and liver by reducing the expression levels of CerS6 and CerK.

CERS6-AS1 contributes to the malignant phenotypes of colorectal cancer cells by interacting with miR-15b-5p to regulate SPTBN2.

Accumulating evidence indicates that long noncoding RNAs (lncRNAs) act as tumor promoters or suppressors in various types of cancer. Previous investigations suggest that ceramide synthase 6 (CERS6) antisense RNA 1 (CERS6-AS1) acts as an oncogene in breast cancer; however, its role in colorectal cancer is unknown. This study aimed to explore the molecular mechanism of CERS6-AS1 in colorectal cancer. Gene expression in colorectal cancer was examined using reverse transcription-quantitative polymerase chain reaction and western blot analyses. The viability and proliferation of colorectal cancer cells were measured by Cell Counting Kit-8 assays and colony formation assays. The migratory and invasive capacities of the colorectal cancer cells were assessed by Transwell assay. Cell stemness was examined by sphere-formation assay. Mechanistically, RNA pull-down assays, RNA immunoprecipitation assays, and luciferase reporter assays were performed to explore the relationship among CERS6-AS1, miR-15b-5p and spectrin beta, non-erythrocytic 2 (SPTBN2). Moreover, a xenograft tumor model was established to investigate the role of CERS6-AS1 in vivo. We found that CERS6-AS1 and SPTBN2 were highly expressed in colorectal cancer tissues and cells. CERS6-AS1 depletion inhibited cell viability, proliferation, migration, and invasion; the epithelial-mesenchymal transition process and stemness. It suppressed xenograft tumor growth in colorectal cancer. Moreover, SPTBN2 levels were positively regulated by CERS6-AS1 and negatively regulated by miR-15b-5p in colorectal cancer cells. Rescue assays revealed that SPTBN2 reversed the inhibitory effect of CERS6-AS1 deficiency on the malignant behaviors of colorectal cancer cells. Overall, the lncRNA CERS6-AS1 facilitates malignant phenotypes of colorectal cancer cells by targeting miR-15b-5p to upregulate SPTBN2.

CERS6-AS1 promotes cell proliferation and represses cell apoptosis in pancreatic cancer via miR-195-5p/WIPI2 axis.

Pancreatic cancer (PC) is a lethal malignancy that threatens human health. Long noncoding RNAs (lncRNAs) act as important mediators in PC development. Our study aimed to investigate the function and mechanism of lncRNA ceramide synthase 6 antisense RNA 1 (CERS6-AS1) in PC. As shown by RT-qPCR, CERS6-AS1 was significantly upregulated in PC cells and tissues. Silencing CERS6-AS1 suppressed PC cell viability and proliferation while enhancing cell apoptosis according to colony formation assays, EdU assays, and flow cytometry analyses. Mechanistically, CERS6-AS1 interacted with miR-195-5p to elevate the expression level of the WD repeat domain phosphoinositide interacting 2 (WIPI2), which is a downstream target gene of miR-195-5p in PC. Moreover, miR-195-5p expression was negatively associated with CERS6-AS1 expression (or WIPI2 expression) in PC tissues. Rescue assays revealed that WIPI2 overexpression rescued the effects of CERS6-AS1 deficiency on cell viability, proliferation, and apoptosis. In summary, CERS6-AS1 facilitates PC cell proliferation while inhibiting PC cell apoptosis by upregulating WIPI2 via miR-195-5p. This study might provide promising insight into the role of CERS6-AS1 in PC development.

Long non-coding RNA CERS6-AS1 plays a prognostic role in promoting the progression of gastric cancer.

This study aims to investigate the potential clinical function of long non-coding RNA CERS6-AS1 (lncRNA CERS6-AS1) integrated miR-567 in gastric cancer. The expression of CERS6-AS1 in gastric cancer tissues was detected through RT-qPCR in contrast to the normal tissues. The correlation between the expression of lncRNA CERS6-AS1 and the characteristics of clinical data was analyzed. Kaplan-Meier curve was used to assess the survival analysis, while Cox proportional hazards model multivariate analysis was performed to evaluate the prognostic risk factors of gastric cancer to verify the prognostic possibility of CERS6-AS1. The expression of CERS6-AS1 in different gastric cancer cells was detected, being the development of gastric cancer cells after knockdown CERS6-AS1 studied using CCK-8, Transwell migration, and invasion detection methods. The targeting effect and interaction between CERS6-AS1 and miR-567 through biological analysis and luciferase activity detection. The expression of lncRNA CERS6-AS1 was elevated in gastric cancer tissues and cells. The results of this study demonstrate that the condition of gastric cancer patients was related to the expression of CERS6-AS1, and therefore CERS6-AS1 might be a prognostic factor for the progression of gastric cancer. In addition, the ability of gastric cancer cells to proliferate, migrate and invade could be reduced by knockdown CERS6-AS1. After CERS6-AS1 knockdown, the expression level of miR-567 in gastric cancer tissues decreased, while the expression level of miR-567 increased. In conclusion, lncRNA CERS6-AS1 might promote the progression of gastric cancer and had the potential as a prognostic marker of gastric cancer.

AKT1/FOXP3 axis-mediated expression of CerS6 promotes p53 mutant pancreatic tumorigenesis.

Ceramide synthases (CerSs) catalyze the formation of ceramides from sphingoid bases and acyl-CoA substrates. Increasing evidence suggests that cancer cells generally exhibit altered sphingolipid metabolism in the tumorigenesis of multiple cancers. However, there is no evidence that CerSs are associated with pancreatic ductal carcinoma (PDAC). In the present study, we examined CerS expression in clinical tissue and conducted data mining to investigate the clinical significance of CerSs in the TCGA-PAAD database. We found that high CerS6 expression positively correlated with progression and predicted worse prognosis in PDAC patients, establishing CerS6 as a potential biomarker for PDAC. Furthermore, CerS6 promoted cell proliferation, colony formation and invasion by producing C16-ceramide and was required for tumor formation. Mechanistically, AKT1 interacted with and phosphorylated FOXP3 at S418, which decreased the binding of FOXP3 to the CERS6 promoter and in turn induced CerS6 expression by reconstituting an activated state on the CERS6 promoter. The AKT1/FOXP3 axis mediated the CerS6 expression and promoted p53 mutant pancreatic tumorigenesis by producing excessive C16-ceramide, which induced the accumulation of mutant p53. Thus, our study explores the relationship between PI3K/AKT signaling and sphingolipid metabolism, revealing an oncogenic role for CerS6, which may represent a potential target for PDAC treatment.

CEBPγ facilitates lamellipodia formation and cancer cell migration through CERS6 upregulation.

Ceramide synthase 6 (CERS6) promotes lung cancer metastasis by stimulating cancer cell migration. To examine the underlying mechanisms, we performed luciferase analysis of the CERS6 promoter region and identified the Y-box as a cis-acting element. As a parallel analysis of database records for 149 non-small-cell lung cancer (NSCLC) cancer patients, we screened for trans-acting factors with an expression level showing a correlation with CERS6 expression. Among the candidates noted, silencing of either CCAAT enhancer-binding protein γ (CEBPγ) or Y-box binding protein 1 (YBX1) reduced the CERS6 expression level. Following knockdown, CEBPγ and YBX1 were found to be independently associated with reductions in ceramide-dependent lamellipodia formation as well as migration activity, while only CEBPγ may have induced CERS6 expression through specific binding to the Y-box. The mRNA expression levels of CERS6, CEBPγ, and YBX1 were positively correlated with adenocarcinoma invasiveness. YBX1 expression was observed in all 20 examined clinical lung cancer specimens, while 6 of those showed a staining pattern similar to that of CERS6. The present findings suggest promotion of lung cancer migration by possible involvement of the transcription factors CEBPγ and YBX1.

Aging-dependent mitochondrial dysfunction mediated by ceramide signaling inhibits antitumor T cell response.

We lack a mechanistic understanding of aging-mediated changes in mitochondrial bioenergetics and lipid metabolism that affect T cell function. The bioactive sphingolipid ceramide, induced by aging stress, mediates mitophagy and cell death; however, the aging-related roles of ceramide metabolism in regulating T cell function remain unknown. Here, we show that activated T cells isolated from aging mice have elevated C14/C16 ceramide accumulation in mitochondria, generated by ceramide synthase 6, leading to mitophagy/mitochondrial dysfunction. Mechanistically, aging-dependent mitochondrial ceramide inhibits protein kinase A, leading to mitophagy in activated T cells. This aging/ceramide-dependent mitophagy attenuates the antitumor functions of T cells in vitro and in vivo. Also, inhibition of ceramide metabolism or PKA activation by genetic and pharmacologic means prevents mitophagy and restores the central memory phenotype in aging T cells. Thus, these studies help explain the mechanisms behind aging-related dysregulation of T cells' antitumor activity, which can be restored by inhibiting ceramide-dependent mitophagy.

Long non-coding RNA CERS6-AS1 facilitates the oncogenicity of pancreatic ductal adenocarcinoma by regulating the microRNA-15a-5p/FGFR1 axis.

The long non-coding RNA CERS6 antisense RNA 1 (CERS6-AS1) has critical regulatory roles in breast cancer progression. Here, we determined CERS6-AS1 expression in pancreatic ductal adenocarcinoma (PDAC) and the roles of CERS6-AS1 in PDAC carcinogenesis. The mechanisms underlying the regulatory actions of CERS6-AS1 in PDAC cells were elucidated in detail. CERS6-AS1 expression was evidently increased in PDAC tissues and cell lines. Patients with PDAC having high CERS6-AS1 expression had shorter overall survival periods than those having low CERS6-AS1 expression. Functionally, the knockdown of CERS6-AS1 attenuated the proliferation, migration, and invasion and stimulated apoptosis of PDAC cells in vitro. Additionally, CERS6-AS1 depletion decreased PDAC tumor growth in vivo. Mechanistically, CERS6-AS1 could competitively bind to microRNA-15a-5p (miR-15a-5p) and effectively work as a molecular sponge in PDAC cells, resulting in the upregulation of fibroblast growth factor receptor 1 (FGFR1), a direct target of miR-15a-5p. Rescue experiments revealed that miR-15a-5p downregulation or FGFR1 restoration rescued the effects of CERS6-AS1 knockdown on the behaviors of PDAC cells. In conclusion, CERS6-AS1 promoted the oncogenicity of PDAC by serving as a competing endogenous RNA to sequester miR-15a-5p and increase FGFR1 expression, which highlights the potential of the CERS6-AS1/miR-15a-5p/FGFR1 pathway as an effective target for cancer therapy.

Ceramide synthase 6 predicts poor prognosis and activates the AKT/mTOR/4EBP1 pathway in high-grade serous ovarian cancer.

Objective: Ovarian cancer is one of the most common gynecological malignancies worldwide, and its mortality rate ranks first among gynecologic cancers. Ceramide synthases are closely related to cancer development. In this study, we investigated the role of ceramide synthase 6 (CerS6) in the development of serous ovarian cancer. Methods: Expression of CerS6 in cancerous and healthy ovarian tissue was assessed by database analysis and immunohistochemistry. The biological role of CerS6 in serous ovarian cancer cells was assessed by CerS6 knockdown followed by cell counting, colony formation, transwell migration, wound healing, and flow cytometry assays and measurement of tumor proliferation in nude mice. Signaling pathway components were analyzed by Western blotting. Gene enrichment was analyzed by GSEA and R, and RNA sequencing was used to compare the transcriptomes of serous ovarian cancer cells with and without CerS6 knockdown. Results: High CerS6 expression in ovarian cancer tissues was closely related to poor prognosis. Knockdown of CerS6 inhibited serous ovarian cancer cell proliferation, invasion, and metastasis and promoted their apoptosis. In addition, CerS6 knockdown increased the proportion of serous ovarian cancer cells in G2/M phase. CerS6 regulates cell cycle through the AKT/mTOR/4EBP1 signaling pathway, which affects cell proliferation and metastasis. The GSEA, R, and RNA sequencing analyses showed that knocking down CerS6 significantly affects cell cycle in serous ovarian cancer cells. Conclusions: CerS6 may have an oncogenic role in ovarian cancer and may represent a new prognostic marker and therapeutic target for serous ovarian cancer.