Dihydroceramide-desaturase-1-mediated caspase 9 activation through ceramide plays a pivotal role in palmitic acid-induced HepG2 cell apoptosis

Sphingolipid metabolism and regulated cell death in malignant melanoma

Malignant melanoma (MM) is a highly invasive and therapeutically resistant skin malignancy, posing a significant clinical challenge in its treatment. Programmed cell death plays a crucial role in the occurrence and progression of MM. Sphingolipids (SP), as a class of bioactive lipids, may be associated with many kinds of diseases. SPs regulate various forms of programmed cell death in tumors, including apoptosis, necroptosis, ferroptosis, and more. This review will delve into the mechanisms by which different types of SPs modulate various forms of programmed cell death in MM, such as their regulation of cell membrane permeability and signaling pathways, and how they influence the survival and death fate of MM cells. An in-depth exploration of the role of SPs in programmed cell death in MM aids in unraveling the molecular mechanisms of melanoma development and holds significant importance in developing novel therapeutic strategies.

Effect of Lard or Plus Soybean Oil on Markers of Liver Function in Healthy Subjects: A Randomized Controlled-Feeding Trial

Humans have consumed lard for thousands of years, but in recent decades, it has become much less popular because it is regarded as saturated fat. Animal studies showed that lard plus soybean oil (blend oil) was more advantageous for liver health than using either oil alone. This study aims to assess the effects of blend oil on liver function markers in healthy subjects. The 345 healthy subjects were randomized into 3 isoenergetic diet groups with different edible oils (30 g/day) (soybean oil, lard, and blend oil (50% lard and 50% soybean oil)) for 12 weeks. The reductions in both aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were greater in the blend oil group than in the two other groups (p = 0.001 and <0.001 for the interaction between diet group and time, respectively). The reductions in AST and ALT in the blend oil group were more significant compared with those in the soybean oil group (p < 0.001) or lard group (p < 0.001). There were no significant differences in the other liver function markers between the groups. Thus, blend oil was beneficial for liver function markers such as AST and ALT compared with soybean oil and lard alone, which might help prevent non-alcoholic fatty liver disease in the healthy population.

Protegrin-1 inhibits porcine ovarian granulosa cell apoptosis from H2O2-induced oxidative stress via the PERK/eIF2α/CHOP signaling pathway in vitro

In mammals, oxidative stress-induced apoptosis of granulosa cells is one of the major causes of follicular atresia, affecting ovarian physiological function. Protegrin-1 (PG-1) is an antimicrobial peptide with effective antimicrobial activity, immunomodulatory function, and porcine growth-promoting effects. PG-1 has been detected in porcine ovaries follicles. This study aimed to investigate the effect of PG-1 on oxidative stress-induced apoptosis of porcine ovarian granulosa cells and the underlying molecular mechanism. Granulosa cells were obtained from porcine follicles and treated with H₂O₂ to establish the oxidative stress model, and then treated with or without PG-1 (10 μg/mL). PG-1 significantly suppressed H₂O₂-induced apoptosis in granulosa cells after 24 h of treatment. Furthermore, these results revealed that PG-1 increased the mRNA and protein expression of anti-apoptotic B cell lymphoma/leukemia 2 (BCL2) and the BCL2/Bcl-2-associated X protein (BAX) ratio while decreasing the expression of pro-apoptotic BAX and active caspase-3. Using Western blot analysis, it was found that PG-1 decreased the phosphorylation of RNA-like endoplasmic reticulum kinase (PERK) and the α-subunit of eukaryotic initiation factor 2 (eIF2α) as well as the protein expression level of CCAAT enhancer-binding protein homologous protein (CHOP), all of which were increased by H₂O₂. Moreover, inhibitors against PERK and phospho-eIF2ɑ both suppressed the H₂O₂-induced granulosa cells apoptosis and enhanced the anti-apoptosis effect of PG-1. Taken together, our findings demonstrated that PG-1 inhibited porcine ovarian granulosa cell apoptosis from oxidative stress via the PERK/eIF2α/CHOP signaling pathway in vitro, which suggests the novel regulatory function of the antimicrobial peptide in the ovary.

An optimized genome-wide, virus-free CRISPR screen for mammalian cells

Pooled CRISPR screens have been widely applied to mammalian and other organisms to elucidate the interplay between genes and phenotypes of interest. The most popular method for delivering the CRISPR components into mammalian cells is lentivirus based. However, because lentivirus is not always an option, virus-free protocols are starting to emerge. Here, we demonstrate an improved virus-free, genome-wide CRISPR screening platform for Chinese hamster ovary cells with 75,488 gRNAs targeting 15,028 genes. Each gRNA expression cassette in the library is precisely integrated into a genomic landing pad, resulting in a very high percentage of single gRNA insertions and minimal clonal variation. Using this platform, we perform a negative selection screen on cell proliferation that identifies 1,980 genes that affect proliferation and a positive selection screen on the toxic endoplasmic reticulum stress inducer, tunicamycin, that identifies 77 gene knockouts that improve survivability.

Phenolics-Enriched Fraction of Pterospermum Lanceifolium Roxb. efficiently Reverses the Hepatocellular Carcinoma in NDEA-Induced HCC Rats

Hepatocellular Carcinoma is one of the most frequently diagnosed cancer and highly refractory for chemotherapeutics agents. Therefore, the study aims to explore the new therapeutic agents for HCC. Phenolics rich fraction of leaves of P. lanceifolium was studied against hepatic cancer cell lines (HepG2) and NDEA-induced HCC rat model system. The obtained results showed that PLE induces reactive oxygen species (ROS) generation and chromatin condensation in nucleus and, alters the mitochondrial membrane potential (MMP) in HepG2 cell lines. The acridine orange/propidium iodide analysis and annexin-V FITC/PI analysis confirms that PLE induces apoptosis-mediated cell death in HepG2-cell lines. In In Vivo analysis, the administration of PLE in NDEA-induced rats declined the elevated biochemicals markers (ALT, AST, ALP, and GGT), interleukins, TNF-α, α-fetoprotein, carcinoembryonic antigen, and total bilirubin. PLE reinstated the level of antioxidant enzyme (GSH, GST, catalase, SOD, and GPX) and the expression of pro-apoptotic (p53, caspase-3, caspase-9, and Bax) and anti-apoptotic (Bcl-2) genes in a dose-dependent manner. The GC-MS analysis of Pterospermum lanceifolium fraction (PLE) represents the presence of palmitic acid, myristic acid, β-sitosterol, and catechin as major bioactive phytocompounds. The study discloses the new lead for HCC that can be further useful for development of new chemopreventive agent.

Role of dihydroceramides in the progression of acute-on-chronic liver failure in rats

Background

Previously, dihydroceramide (d18:0/24:0) (dhCer (d18:0/24:0)) was reported to be a potential biomarker for acute-on-chronic liver failure (ACLF) prognosis. In this study, we further explored the role of dhCer (d18:0/24:0) in the progression of ACLF to validate the biomarker using ACLF rat model.

Methods

ACLF rats were sacrificed at 4 and 8 h post-D-galactosamine (D-gal)/lipopolysaccharide (LPS) administration to investigate the liver biochemical markers, prothrombin time and liver histopathology. Change in dhCer and other sphingolipids levels were investigated by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Rats were treated with N-(4-hydroxyphenyl) retinamide (4-HPR) to examine the mortality rate and its role in improving ACLF.

Results

LPS/D-gal administration resulted in significant elevation in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Prothrombin time was prolonged and histopathological examination showed abnormality. HPLC-MS/MS results showed total dhCer levels in ACLF group (64.10 ± 8.90 pmol/100 μL, 64.22 ± 6.78 pmol/100 μL for 4 and 8 h, respectively) were decreased significantly compared with control group (121.61 ± 23.09 pmol/100 μL) (P < 0.05). In particular, dhCer (d18:0/24:0), dhCer (d18:0/20:0), and dhCer (d18:0/22:0) levels were decreased. Treatment with 4-HPR significantly increased the levels of dhCers, including dhCer (d18:0/24:0) compared with ACLF group, for the level of dhCer (d18:0/24:0) in 4-HPR group was 20.10 ± 8.60 pmol/100 μL and the level of dhCer (d18:0/24:0) in ACLF group was 9.74 ± 2.99 pmol/100 μL (P < 0.05). This was associated with reduced mortality rate and prolonged survival time. The ALT and AST in 4-HPR group were significantly decreased compared with ACLF group. The prothrombin time of 4-HPR group (41.49 s) was significantly lower than the prothrombin time of ACLF group (57.96 s) (P < 0.05). 4-HPR also decreased plasma ammonia levels slightly, as the plasma ammonia levels in 4-HPR group and ACLF group were 207.37 ± 60.43, 209.15 ± 60.43 μmol/L, respectively. Further, 4-HPR treatment improved histopathological parameters.

Conclusions

DhCer, especially dhCer (d18:0/24:0), is involved in the progression of ACLF. Increasing the levels of dhCer can reduce the mortality rate of ACLF rats and alleviate liver injury.

Vaticanol C, a phytoalexin, induces apoptosis of leukemia and cancer cells by modulating expression of multiple sphingolipid metabolic enzymes

Resveratrol (RSV) has recently attracted keen interest because of its pleiotropic effects. It exerts a wide range of health-promoting effects. In addition to health-promoting effects, RSV possesses anti-carcinogenic activity. However, a non-physiological concentration is needed to achieve an anti-cancer effect, and its in vivo bioavailability is low. Therefore, the clinical application of phytochemicals requires alternative candidates that induce the desired effects at a lower concentration and with increased bioavailability. We previously reported a low IC₅₀ of vaticanol C (VTC), an RSV tetramer, among 12 RSV derivatives (Ito T. et al, 2003). However, the precise mechanism involved remains to be determined. Here, we screened an in-house chemical library bearing RSV building blocks ranging from dimers to octamers for cytotoxic effects in several leukemia and cancer cell lines and their anti-cancer drug-resistant sublines. Among the compounds, VTC exhibited the highest cytotoxicity, which was partially inhibited by a caspase 3 inhibitor, Z-VAD-FMK. VTC decreased the expression of sphingosine kinase 1, sphingosine kinase 2 and glucosylceramide synthase by transcriptional or post-transcriptional mechanisms, and increased cellular ceramides/dihydroceramides and decreased sphingosine 1-phosphate (S1P). VTC-induced sphingolipid rheostat modulation (the ratio of ceramide/S1P) is thought to be involved in cellular apoptosis. Indeed, exogenous S1P addition modulated VTC cytotoxicity significantly. A combination of SPHK1, SPHK2, and GCS chemical inhibitors induced sphingolipid rheostat modulation, cell growth suppression, and cytotoxicity similar to that of VTC. These results suggest the involvement of sphingolipid metabolism in VTC-induced cytotoxicity, and indicate VTC is a promising prototype for translational research.

Melatonin attenuates palmitic acid-induced mouse granulosa cells apoptosis via endoplasmic reticulum stress

BACKGROUND

Palmitic acid (PA), the main component of dietary saturated fat, causes apoptosis in many cell types, including mouse granulosa cell. Melatonin, an important endogenous hormone, has beneficial effects on female reproductive processes. Since elevated PA levels are present in follicular fluid (FF) of patients with infertility and are shown to be toxic for granulosa cells, we investigated the molecular mechanisms of PA toxicity in mouse granulosa cells and explored the effects of melatonin on PA-induced apoptosis.

METHODS

Granulosa cells from immature female mice were cultured for 24 h in medium containing PA and/or melatonin. Then, the effects of PA alone or combined with melatonin on viability, apoptosis and endoplasmic reticulum (ER) stress in granulosa cells were detected by methyl thiazolyl tetrazolium (MTT) assay, flow cytometry assay and western blot. After 48 h of PA and/or melatonin treatment, the concentrations of estradiol (E2) and progesterone (P4) in the culture supernatants were measured with ELISA kits.

RESULTS

In this study, we explored the effects of melatonin on cell viability and apoptosis in PA-treated mouse granulosa cells and uncovered the signaling pathways involved in these processes. Our results showed that 200-800 μM PA treatment reduces cell viability, induces cell apoptosis, enhances the expression of apoptosis-related genes (Caspase 3 and B-cell lymphoma-2 (BCL-2) associated X protein (BAX)), and activates the expression of ER stress marker genes (glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP)). Melatonin treatment (1-10 μM) suppresses 400 μM PA-induced cell viability decrease, cell apoptosis, Caspase 3 activation, and BAX, CHOP, and GRP78 expression. In addition, we found that 10 μM melatonin successfully attenuated the 400 μM PA-induced estrogen (E2) and progesterone (P4) decreases.

CONCLUSIONS

This study suggests that PA triggers cell apoptosis via ER stress and that melatonin protects cells against apoptosis by inhibiting ER stress in mouse granulosa cells.

Survival of Lymphoma-Bearing Mice by Pachycereus marginatus Cactus Extracts and Elucidation of Bioactive Compounds

Cancer is one of the leading causes of death worldwide and commonly becomes resistant to chemotherapy, therefore, it is important to search for and evaluate novel sources of nontoxic antitumor agents. The cactus Pachycereus marginatus is native to Mexico and is traditionally recommended to treat gastrointestinal infections. Tumor-bearing mice survival, liver function, and histopathology by P. marginatus extracts and the in vitro effects of isolated compounds lophenol, β-sitosterol, and palmitic acid were investigated, using the L5178Y-R lymphoma murine model. In vivo oral administration of the aqueous partition at 0.5 mg/kg caused 60% survival at 60 days, without altering liver parenchyma and enzymes, as compared with 40% survival induced by vincristine (0.05 mg/kg), and no survival of tumor-bearing mice without treatment. Furthermore, P. marginatus n-hexane extract, lophenol, β-sitosterol, and palmitic acid compounds caused up to 89%, 73%, and 83% in vitro cytotoxicity to L5178Y-R cells, respectively. These results may support the evaluation of P. marginatus extracts and bioactive compounds in clinical studies.

Sphingomyelin synthase 2 promotes an aggressive breast cancer phenotype by disrupting the homoeostasis of ceramide and sphingomyelin

Breast cancer is the most common type of carcinoma in women worldwide, but the mechanisms underlying tumour development and progression remain unclear. Sphingomyelin synthase 2 (SGMS2) is a crucial regulator involved in ceramide (Cer) and sphingomyelin (SM) homoeostasis that is mostly studied for its role in lipid metabolism. Our primary study indicated that high SGMS2 expression is associated with breast cancer metastasis. Gain- and loss-of-function assays in vitro and in vivo revealed that SGMS2 promotes cancer cell proliferation by suppressing apoptosis through a Cer-associated pathway and promotes cancer cell invasiveness by enhancing epithelial-to-mesenchymal transition (EMT) initiation through the TGF-β/Smad signalling pathway. Further study determined that SGMS2 activated the TGF-β/Smad signalling pathway primarily by increasing TGF-β1 secretion, which was likely associated with aberrant expression of SM. Thus, our findings indicate that SGMS2-mediated activation of the TGF-β/Smad signalling pathway is important in breast cancer progression, which provides new insight into the mechanisms underlying breast cancer metastasis and suggests a possible anticancer therapy for breast cancer.

Palmitic acid induces human osteoblast-like Saos-2 cell apoptosis via endoplasmic reticulum stress and autophagy

Palmitic acid (PA) is the most common saturated long-chain fatty acid in food that causes cell apoptosis. However, little is known about the molecular mechanisms of PA toxicity. In this study, we explore the effects of PA on proliferation and apoptosis in human osteoblast-like Saos-2 cells and uncover the signaling pathways involved in the process. Our study showed that endoplasmic reticulum (ER) stress and autophagy are involved in PA-induced Saos-2 cell apoptosis. We found that PA inhibited the viability of Saos-2 cells in a dose- and time-dependent manner. At the same time, PA induced the expression of ER stress marker genes (glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP)), altered autophagy-related gene expression (microtubule-associated protein 1 light chain 3 (LC3), ATG5, p62, and Beclin), promoted apoptosis-related gene expression (Caspase 3 and BAX), and affected autophagic flux. Inhibiting ER stress with 4-PBA diminished the PA-induced cell apoptosis, activated autophagy, and increased the expression of Caspase 3 and BAX. Inhibiting autophagy with 3-MA attenuated the PA and ER stress-induced cell apoptosis and the apoptosis-related gene expression (Caspase 3 and BAX), but seemed to have no obvious effects on ER stress, although the CHOP expression was downregulated. Taken together, our results suggest that PA-induced Saos-2 cell apoptosis is activated via ER stress and autophagy, and the activation of autophagy depends on the ER stress during this process.

Vaginal lipidomics of women with vulvovaginal candidiasis and cytolytic vaginosis: A non-targeted LC-MS pilot study

Objective

To characterize the lipid profile in vaginal discharge of women with vulvovaginal candidiasis, cytolytic vaginosis, or no vaginal infection or dysbiosis.

Design

Cross-sectional study.

Setting

Genital Infections Ambulatory, Department of Tocogynecology, University of Campinas, Campinas, São Paulo–Brazil.

Sample

Twenty-four women were included in this study: eight with vulvovaginal candidiasis, eight with cytolytic vaginosis and eight with no vaginal infections or dysbiosis (control group).

Methods

The lipid profile in vaginal discharge of the different study groups was determined by liquid chromatography-mass spectrometry and further analyzed with MetaboAnalyst 3.0 platform.

Main outcome measures

Vaginal lipids concentration and its correlation with vulvovaginal candidiasis and cytolytic vaginosis.

Results

PCA, PLS-DA and hierarchical clustering analyses indicated 38 potential lipid biomarkers for the different groups, correlating with oxidative stress, inflammation, apoptosis and integrity of the vaginal epithelial tissue. Among these, greater concentrations were found for Glycochenodeoxycholic acid-7-sulfate, O-adipoylcarnitine, 1-eicosyl-2-heptadecanoyl-glycero-3-phosphoserine, undecanoic acid, formyl dodecanoate and lipoic acid in the vulvovaginal candidiasis group; N–(tetradecanoyl)-sphinganine, DL-PPMP, 1-oleoyl-cyclic phosphatidic, palmitic acid and 5-aminopentanoic acid in the cytolytic vaginosis group; and 1-nonadecanoyl-glycero-3-phosphate, eicosadienoic acid, 1-stearoyl-cyclic-phosphatidic acid, 1-(9Z,12Z-heptadecadienoyl)-glycero-3-phosphate, formyl 9Z-tetradecenoate and 7Z,10Z-hexadecadienoic acid in the control group.

Conclusions

Lipids related to oxidative stress and apoptosis were found in higher concentrations in women with vulvovaginal candidiasis and cytolytic vaginosis, while lipids related to epithelial tissue integrity were more pronounced in the control group. Furthermore, in women with cytolytic vaginosis, we observed higher concentrations of lipids related to bacterial overgrowth.

Cytotoxic effect of Kalanchoe flammea and induction of intrinsic mitochondrial apoptotic signaling in prostate cancer cells

ETHNOPHARMACOLOGICAL IMPORTANCE

Kalanchoe flammea Stapf (Crassulaceae) is a medicinal plant grown in the South of Mexico (State of Tabasco), which is commonly used in traditional medicine for the treatment of fever, wounds, inflammation, and cancer.

AIM OF THE STUDY

To establish the potential of K. flammea for the treatment of prostate cancer, evaluating its cytotoxic activity, its probable mechanism of action, and carrying out some toxicological safety studies.

MATERIALS AND METHODS

The cytotoxic activity of the ethyl acetate extract of K. flammea (Kf-EtOAc) was evaluated in several cell lines of prostate cancer by MTT viability assay. The cellular death mechanism was studied by evaluating the translocation of phosphatidylserine (Annexin V); overproduction of reactive oxygen species [2'-7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) assay]; release of Cytochrome C; activation of caspase-3 and -9, and regulation of Bcl-2, XIAP, and PKCε proteins by Western Blot analysis. For the evaluation of the safety of Kf-EtOAc, the Ames test, Micronucleus assay, and acute toxicity study were determined.

RESULTS

Kf-EtOAc exhibited selective cytotoxic activity against prostate cell lines as follows: PC-3, LNCaP, and PrEC (IC₅₀ = 1.36 ± 0.05; 2.06 ± 0.02, and 127.05 ± 0.07 μg/mL, respectively). The F82-P2 fraction (rich in coumaric acid and palmitic acid) obtained by bioassay-guided fractionation of Kf-EtOAc also demonstrated selective cytotoxic activity against PC-3 cells (IC₅₀ = 1.05 ± 0.06 μg/mL). Kf-EtOAc induces apoptosis by the intrinsic pathway; this mechanism of cell death was confirmed after observing that the extract produces phosphatidylserine translocation, overproduction of reactive oxygen species, release of Cytochrome C at mitochondrial level, and activation of caspase-3 and -9. It was also observed that Kf-EtOAc produces significant downregulation of apoptosis-related proteins Bcl-2, XIAP, and PKCε and induces DNA fragmentation and cell cycle arrest. In addition, Kf-EtOAc is non-genotoxic in vitro by Ames test and non-genotoxic in vivo by Micronucleus assay, and no signs of toxicity or death were reported after the administration of a single acute exposure of 2000 mg/kg.

CONCLUSION

K. flammea is a potential candidate for the development of new drugs for the treatment of prostate cancer. However, to propose their use in clinical trials, additional studies are required to understand their pharmacokinetic behavior, as well as the development of a suitable pharmaceutical form.

Non-alcoholic fatty liver disease: Insights from sphingolipidomics

Non-alcoholic fatty liver disease (NAFLD) is a major clinical concern and its treatment consumes abundant resources. While accumulation of lipids in hepatocytes initiates the disease, this in itself is not necessarily harmful; rather, initiation of inflammation and subsequent fibrosis and cirrhosis are critical steps in NAFLD pathology. Mechanisms linking lipid overload to downstream disease progression are not fully understood; however, bioactive lipid metabolism may underlie instigation of proinflammatory signaling. With the advent of high-throughput, sensitive, and quantitative mass spectrometry-based methods for assessing lipid profiles in NAFLD, several trends have emerged, including that increases in specific sphingolipids correlate with the transition from the relatively benign condition of simple fatty liver to the much more concerning inflamed state. Continued studies that implement sphingolipid profiling will enable the extrapolations of candidate enzymes and pathways involved in NAFLD, either in biopsies or plasma from human samples, and also in animal models, from which data are much more abundant. While most data thus far are derived from targeted lipidomics approaches, unbiased, semi-quantitative approaches hold additional promise for furthering our understanding of sphingolipids as markers of and players in NAFLD.

Effect of triptolide on expression of Bax/Bcl-2 and cleaved Caspase 3 in HCT116 cells

AIM

To investigate the effect of triptolide (TP) on the expression of Bax/B cell lymphoma/leukmia-2 (Bcl-2) and cleaved Caspase 3 in HCT116 cells and the mechanism of TP induced apoptosis.

METHODS

HCT116 cells were divided into six groups and treated with 5, 10, 20, 30, 40, and 80 nmol/L TP, respectively. HCT116 cells treated with PBS were used control cells. After HCT116 cells were exposed to TP for 24 h, 48 h or 72 h, MTT assay was used for estimating the survival rates of HCT116 cells, flow cytometry (FCM) was applied to test the effects of TP on cell apoptosis, and Western blot was used for testing the expression of Bcl-2, Bax, Caspase 3, and activated Caspase 3.

RESULTS

TP could inhibit the proliferation of HCT116 cells. The survival rates of HCT116 cells decreased with the increase in the concentration and treatment time of TP. The survival rates were 4.25%, 13.6%, 34.4%, 43.8% and 44.5%, respectively, for cells exposed to 5, 10, 20, 30, and 40 nmol/L TP for 48h. The expression of Bcl-2 was decreased with the increase in the concentration of TP. Additionally, the level of Bax was decreased in the cytoplasm but increased in mitochondria, indicating that TP can promote Bax translocation from the cytoplasm to mitochondria. TP reduced the level of Caspase 3 in a concentration dependent manner; however, cleaved Caspase 3 level was increased.

CONCLUSION

TP can induce apoptosis of HCT116 cells by inhibiting the expression of Bcl-2, increasing the expression of Bax, and promoting the activation of Caspase 3.