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.

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.

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.

lncRNA CERS6-AS1 as ceRNA promote cell proliferation of breast cancer by sponging miR-125a-5p to upregulate BAP1 expression.

Long noncoding RNAs (lncRNAs) can act as oncogene and tumor suppressor genes in many types of cancers including breast cancer (BC). Our previous study has indicated microRNA (miR)-125a-5p was downregulated and function as a tumor suppressor in BC. However, its upstream regulation mechanism is still unclear. In this study, we used bioinformatics algorithms, RNA pulldown assay, and dual-luciferase reports assay to predict and confirm lncRNA CERS6-AS1 interacted with miR-125a-5p. Then we found CERS6-AS1 was upregulated in BC tissues. Experimental results of tumor growth in nude mice show that CERS6-AS1 promotes tumor growth. Furthermore, CERS6-AS1 regulated BC susceptibility gene 1-associated protein 1 (BAP1) expression via sponging miR-125a-5p via Western blot analysis and quantitative polymerase chain reaction arrays. Finally, we showed that miR-125a-5p had opposing effects to those of CERS6-AS1 on BC cells, demonstrating that CERS6-AS1 may promote cell proliferation and inhibit cell apoptosis via sponging miR-125a-5p. Our results indicated CERS6-AS1 promote BC cell proliferation and inhibit cell apoptosis via sponging miR-125a-5p to upregulate BAP1 expression.

A novel role for ceramide synthase 6 in mouse and human alcoholic steatosis.

Perilipin 2 (PLIN2) is a lipid-droplet protein that is up-regulated in alcoholic steatosis and associated with hepatic accumulation of ceramides, bioactive lipids implicated in alcoholic liver disease pathogenesis. The specific role of ceramide synthetic enzymes in the regulation of PLIN2 and promotion of hepatocellular lipid accumulation is not well understood. We examined the effects of pharmacologic ceramide synthesis inhibition on hepatic PLIN2 expression, steatosis, and glucose and lipid homeostasis in mice with alcoholic steatosis and in ethanol-incubated human hepatoma VL17A cells. In cells, pharmacologic inhibition of ceramide synthase reduced lipid accumulation by reducing PLIN2 RNA stability. The subtype ceramide synthase (CerS)6 was specifically up-regulated in experimental alcoholic steatosis in vivo and in vitro and was up-regulated in zone 3 hepatocytes in human alcoholic steatosis. In vivo ceramide reduction by inhibition of de novo ceramide synthesis reduced PLIN2 and hepatic steatosis in alcohol-fed mice, but only de novo synthesis inhibition, not sphingomyelin hydrolysis, improved glucose tolerance and dyslipidemia. These findings implicate CerS6 as a novel regulator of PLIN2 and suggest that ceramide synthetic enzymes may promote the earliest stage of alcoholic liver disease, alcoholic steatosis.-Williams, B., Correnti, J., Oranu, A., Lin, A., Scott, V., Annoh, M., Beck, J., Furth, E., Mitchell, V., Senkal, C. E., Obeid, L., Carr, R. M. A novel role for ceramide synthase 6 in mouse and human alcoholic steatosis.

CerS6 regulates cisplatin resistance in oral squamous cell carcinoma by altering mitochondrial fission and autophagy.

Chemoresistance remains a challenge in the effective treatment of solid tumors, including oral squamous cell carcinoma (OSCC). Mitochondrial dynamics and autophagy have recently been implicated in the chemoresistance of cancer cells. The neutralization of ceramide is also associated with multidrug resistance, and ceramide synthase 6 (CerS6) is known to induce apoptosis. However, whether CerS6 regulates chemoresistance in OSCC is not clearly understood. Therefore, we investigated the role of CerS6 in the susceptibility of OSCC cells to cisplatin. In this study, we observed that cisplatin-resistant OSCC cells process lower levels of fission-state mitochondria and cell apoptosis than cisplatin-sensitive cells, and autophagy was activated in cisplatin-resistant OSCC cells. We found lower CerS6 expression in cisplatin-resistant OSCC cells. Overexpression of CerS6 with lentivirus-encoded CerS6 complementary DNA in cisplatin-resistant OSCC cells increased cisplatin sensitivity. Overexpression of CerS6 enhanced mitochondrial fission and apoptosis and attenuated cisplatin-induced autophagy in cisplatin-resistant OSCC cells. Further investigation indicated that CerS6 might function through altering calpain expression to enhance cisplatin sensitivity. Cisplatin-resistant OSCC cells xenografted onto a nude mouse model confirmed that CerS6 enhanced cisplatin chemotherapy sensitivity to reduce tumor volume. These data indicate that CerS6 could mediate an effective response to cisplatin in chemoresistant OSCC.

Ceramide synthase 6 predicts the prognosis of human gastric cancer: It functions as an oncoprotein by dysregulating the SOCS2/JAK2/STAT3 pathway.

Although gastric cancer (GC) is one of the most common cancers, knowledge of its development, and carcinogenesis is limited. The present study explored the involvement of ceramide synthase 6 (CERS6) in GC carcinogenesis and prognosis. RT-PCR, immunoblotting, and immunohistochemistry were used to examine the expression of CERS6. Transfection and small hairpin RNA technology were used to investigate the effect of CERS6 manipulation on cell proliferation and spread as well as the underlying mechanism. Moreover, xenograft proliferation was employed to explore the influence of CERS6 on tumor growth in animals. It was found that overexpression of CERS6 was significantly correlated with several clinicopathologic parameters and poor disease-free survival. The overexpression and silencing of CERS6 in GC cells facilitated and suppressed cell proliferation and spread as well as xenograft proliferation, respectively. Mechanistic studies further revealed that CERS6 influenced cell proliferation and spread by regulating cell cycle control and metastasis-related protein through the SOCS2/JAK2/STAT3 signaling pathway. Collectively, this study suggests that CERS6 overexpression could be a useful biomarker for predicting the outcomes of GC patients and that CERS6 targeting represents a potential modality for treating GC.

Folate stress induces apoptosis via p53-dependent de novo ceramide synthesis and up-regulation of ceramide synthase 6.

We have investigated the role of ceramide in the cellular adaptation to folate stress induced by Aldh1l1, the enzyme involved in the regulation of folate metabolism. Our previous studies demonstrated that Aldh1l1, similar to folate deficiency, evokes metabolic stress and causes apoptosis in cancer cells. Here we report that the expression of Aldh1l1 in A549 or HCT116 cells results in the elevation of C16-ceramide and a transient up-regulation of ceramide synthase 6 (CerS6) mRNA and protein. Pretreatment with ceramide synthesis inhibitors myriocin and fumonisin B1 or siRNA silencing of CerS6 prevented C16-ceramide accumulation and rescued cells supporting the role of CerS6/C16-ceramide as effectors of Aldh1l1-induced apoptosis. The CerS6 activation by Aldh1l1 and increased ceramide generation were p53-dependent; this effect was ablated in p53-null cells. Furthermore, the expression of wild type p53 but not transcriptionally inactive R175H p53 mutant strongly elevated CerS6. Also, this dominant negative mutant prevented accumulation of CerS6 in response to Aldh1l1, indicating that CerS6 is a transcriptional target of p53. In support of this mechanism, bioinformatics analysis revealed the p53 binding site 3 kb downstream of the CerS6 transcription start. Interestingly, ceramide elevation in response to Aldh1l1 was inhibited by silencing of PUMA, a proapoptotic downstream effector of p53 whereas the transient expression of CerS6 elevated PUMA in a p53-dependent manner indicating reciprocal relationships between ceramide and p53/PUMA pathways. Importantly, folate withdrawal also induced CerS6/C16-ceramide elevation accompanied by p53 accumulation. Overall, these novel findings link folate and de novo ceramide pathways in cellular stress response.

Inactivation of ceramide synthase 6 in mice results in an altered sphingolipid metabolism and behavioral abnormalities.

The N-acyl chain length of ceramides is determined by the specificity of different ceramide synthases (CerS). The CerS family in mammals consists of six members with different substrate specificities and expression patterns. We have generated and characterized a mouse line harboring an enzymatically inactive ceramide synthase 6 (CerS6KO) gene and lacz reporter cDNA coding for ß-galactosidase directed by the CerS6 promoter. These mice display a decrease in C16:0 containing sphingolipids. Relative to wild type tissues the amount of C16:0 containing sphingomyelin in kidney is ∼35%, whereas we find a reduction of C16:0 ceramide content in the small intestine to about 25%. The CerS6KO mice show behavioral abnormalities including a clasping abnormality of their hind limbs and a habituation deficit. LacZ reporter expression in the brain reveals CerS6 expression in hippocampus, cortex, and the Purkinje cell layer of the cerebellum. Using newly developed antibodies that specifically recognize the CerS6 protein we show that the endogenous CerS6 protein is N-glycosylated and expressed in several tissues of mice, mainly kidney, small and large intestine, and brain.

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.

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.

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.

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.

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 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.

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.