PNPLA3 is a triglyceride lipase that mobilizes polyunsaturated fatty acids to facilitate hepatic secretion of large-sized very low-density lipoprotein.

The I148M variant of PNPLA3 is closely associated with hepatic steatosis. Recent evidence indicates that the I148M mutant functions as an inhibitor of PNPLA2/ATGL-mediated lipolysis, leaving the role of wild-type PNPLA3 undefined. Despite showing a triglyceride hydrolase activity in vitro, PNPLA3 has yet to be established as a lipase in vivo. Here, we show that PNPLA3 preferentially hydrolyzes polyunsaturated triglycerides, mobilizing polyunsaturated fatty acids for phospholipid desaturation and enhancing hepatic secretion of triglyceride-rich lipoproteins. Under lipogenic conditions, mice with liver-specific knockout or acute knockdown of PNPLA3 exhibit aggravated liver steatosis and reduced plasma VLDL-triglyceride levels. Similarly, I148M-knockin mice show decreased hepatic triglyceride secretion during lipogenic stimulation. Our results highlight a specific context whereby the wild-type PNPLA3 facilitates the balance between hepatic triglyceride storage and secretion, and suggest the potential contribution of a loss-of-function by the I148M variant to the development of fatty liver disease in humans.

ABCA7 deficiency causes neuronal dysregulation by altering mitochondrial lipid metabolism.

ABCA7 loss-of-function variants are associated with increased risk of Alzheimer's disease (AD). Using ABCA7 knockout human iPSC models generated with CRISPR/Cas9, we investigated the impacts of ABCA7 deficiency on neuronal metabolism and function. Lipidomics revealed that mitochondria-related phospholipids, such as phosphatidylglycerol and cardiolipin were reduced in the ABCA7-deficient iPSC-derived cortical organoids. Consistently, ABCA7 deficiency-induced alterations of mitochondrial morphology accompanied by reduced ATP synthase activity and exacerbated oxidative damage in the organoids. Furthermore, ABCA7-deficient iPSC-derived neurons showed compromised mitochondrial respiration and excess ROS generation, as well as enlarged mitochondrial morphology compared to the isogenic controls. ABCA7 deficiency also decreased spontaneous synaptic firing and network formation in iPSC-derived neurons, in which the effects were rescued by supplementation with phosphatidylglycerol or NAD+ precursor, nicotinamide mononucleotide. Importantly, effects of ABCA7 deficiency on mitochondria morphology and synapses were recapitulated in synaptosomes isolated from the brain of neuron-specific Abca7 knockout mice. Together, our results provide evidence that ABCA7 loss-of-function contributes to AD risk by modulating mitochondria lipid metabolism.

Dhr96[1] mutation and maternal tudor[1] mutation increase life span and reduce the beneficial effects of mifepristone in mated female Drosophila.

Mating and receipt of male Sex Peptide hormone cause increased egg laying, increased midgut size and decreased life span in female Drosophila. Feeding mated females with the synthetic steroid mifepristone decreases egg production, reduces midgut size, and increases life span. Here, several gene mutations were assayed to investigate possible mechanisms for mifepristone action. Drosophila Dhr96 is a hormone receptor, and a key positive regulator of midgut lipid uptake and metabolism. Dhr96[1] null mutation increased female life span, and reduced the effects of mifepristone on life span, suggesting that Dhr96[1] mutation and mifepristone may act in part through the same mechanism. Consistent with this idea, lipidomics analysis revealed that mating increases whole-body levels of triglycerides and fatty-acids in triglycerides, and these changes are reversed by mifepristone. Maternal tudor[1] mutation results in females that lack the germ-line and produce no eggs. Maternal tudor[1] mutation increased mated female life span, and reduced but did not eliminate the effects of mating and mifepristone on life span. This indicates that decreased egg production may be related to the life span benefits of mifepristone, but is not essential. Mifepristone increases life span in w[1118] mutant mated females, but did not increase life span in w[1118] mutant virgin females. Mifepristone decreased egg production in w[1118] mutant virgin females, indicating that decreased egg production is not sufficient for mifepristone to increase life span. Mifepristone increases life span in virgin females of some, but not all, white[+] and mini-white[+] strains. Backcrossing of mini-white[+] transgenes into the w[1118] background was not sufficient to confer a life span response to mifepristone in virgin females. Taken together, the data support the hypothesis that mechanisms for mifepristone life span increase involve reduced lipid uptake and/or metabolism, and suggest that mifepristone may increase life span in mated females and virgin females through partly different mechanisms.

Substrate-Specific Function of PNPLA3 Facilitates Hepatic VLDL-Triglyceride Secretion During Stimulated Lipogenesis.

The I148M variant of PNPLA3 is strongly linked to hepatic steatosis. Evidence suggests a gain-of-function role for the I148M mutant as an ATGL inhibitor, leaving the physiological relevance of wild-type PNPLA3 undefined. Here we show that PNPLA3 selectively degrades triglycerides (TGs) enriched in polyunsaturated fatty acids (PUFAs) independently of ATGL in cultured cells and mice. Lipidomics and metabolite tracing analyses demonstrated that PNPLA3 mobilizes PUFAs from intracellular TGs for phospholipid desaturation, supporting hepatic secretion of TG-rich lipoproteins. Consequently, mice with liver-specific knockout or acute knockdown of PNPLA3 both exhibited aggravated liver steatosis and concomitant decreases in plasma VLDL-TG, phenotypes that manifest only under lipogenic conditions. I148M-knockin mice similarly displayed impaired hepatic TG secretion during lipogenic stimulation. Our results highlight a specific context whereby PNPLA3 facilitates the balance between hepatic TG storage and secretion and suggest the potential contributions of I148M variant loss-of-function to the development of hepatic steatosis in humans. Summary Statement: We define the physiological role of wild type PNPLA3 in maintaining hepatic VLDL-TG secretion.

HILPDA promotes NASH-driven HCC development by restraining intracellular fatty acid flux in hypoxia.

BACKGROUND & AIMS: The prevalence of non-alcoholic steatohepatitis (NASH)-driven hepatocellular carcinoma (HCC) is rising rapidly, yet its underlying mechanisms remain unclear. Herein, we aim to determine the role of hypoxia-inducible lipid droplet associated protein (HILPDA)/hypoxia-inducible gene 2 (HIG2), a selective inhibitor of intracellular lipolysis, in NASH-driven HCC. METHODS: The clinical significance of HILPDA was assessed in human NASH-driven HCC specimens by immunohistochemistry and transcriptomics analyses. The oncogenic effect of HILPDA was assessed in human HCC cells and in 3D epithelial spheroids upon exposure to free fatty acids and either normoxia or hypoxia. Lipidomics profiling of wild-type and HILPDA knockout HCC cells was assessed via shotgun and targeted approaches. Wild-type (Hilpdafl/fl) and hepatocyte-specific Hilpda knockout (HilpdaΔHep) mice were fed a Western diet and high sugar in drinking water while receiving carbon tetrachloride to induce NASH-driven HCC. RESULTS: In patients with NASH-driven HCC, upregulated HILPDA expression is strongly associated with poor survival. In oxygen-deprived and lipid-loaded culture conditions, HILPDA promotes viability of human hepatoma cells and growth of 3D epithelial spheroids. Lack of HILPDA triggered flux of polyunsaturated fatty acids to membrane phospholipids and of saturated fatty acids to ceramide synthesis, exacerbating lipid peroxidation and apoptosis in hypoxia. The apoptosis induced by HILPDA deficiency was reversed by pharmacological inhibition of ceramide synthesis. In our experimental mouse model of NASH-driven HCC, HilpdaΔHep exhibited reduced hepatic steatosis and tumorigenesis but increased oxidative stress in the liver. Single-cell analysis supports a dual role of hepatic HILPDA in protecting HCC cells and facilitating the establishment of a pro-tumorigenic immune microenvironment in NASH. CONCLUSIONS: Hepatic HILPDA is a pivotal oncometabolic factor in the NASH liver microenvironment and represents a potential novel therapeutic target. IMPACT AND IMPLICATIONS: Non-alcoholic steatohepatitis (NASH, chronic metabolic liver disease caused by buildup of fat, inflammation and damage in the liver) is emerging as the leading risk factor and the fastest growing cause of hepatocellular carcinoma (HCC), the most common form of liver cancer. While curative therapeutic options exist for HCC, it frequently presents at a late stage when such options are no longer effective and only systemic therapies are available. However, systemic therapies are still associated with poor efficacy and some side effects. In addition, no approved drugs are available for NASH. Therefore, understanding the underlying metabolic alterations occurring during NASH-driven HCC is key to identifying new cancer treatments that target the unique metabolic needs of cancer cells.

Dietary Fats High in Linoleic Acids Impair Antitumor T-cell Responses by Inducing E-FABP-Mediated Mitochondrial Dysfunction.

The most recent American Dietary Guidelines (2020-2025) recommend shifting dietary fats from solid saturated fats to unsaturated oils. Dietary oils contain different compositions of unsaturated fatty acids (UFA). Oleic acid (OA) and linoleic acid (LA) are the most common UFA in dietary oils. How individual UFA in oils regulate immune cell function and cancer risk remains unclear. Here we demonstrated that high-fat diets (HFD) rich either in OA or LA induced a similar degree of murine obesity, but the LA-rich HFD specifically promoted mammary tumor growth. LA impaired antitumor T-cell responses by promoting naïve T-cell apoptosis and inhibiting TNFα production. While exogenous OA and LA were taken up by T cells with similar efficacy, only LA induced significant mitochondrial reactive oxygen species production and lipid peroxidation. Importantly, naïve T cells predominantly expressed epidermal fatty acid binding protein (E-FABP), which is central in facilitating LA mitochondrial transport and cardiolipin incorporation. Genetic depletion of E-FABP rescued LA-impaired T-cell responses and suppressed LA-rich HFD-associated mammary tumor growth. Collectively, these data suggest that dietary oils high in LA promote mammary tumors by inducing E-FABP-mediated T-cell dysfunction. SIGNIFICANCE: These findings suggest that modulation of dietary oil composition and inhibition of E-FABP activity may represent novel strategies to enhance T-cell function in the prevention and treatment of obesity-associated cancers.

The impact of camptothecin-encapsulated poly(lactic-co-glycolic acid) nanoparticles on the activity of cytochrome P450 in vitro.

BACKGROUND: Poly(lactic-co-glycolic acid) (PLGA) has emerged as a promising anticancer drug delivery scaffold. Camptothecin (CPT) has been fabricated into a variety of nanosized formulations to improve drug action. We report an experimental study on the effect of CPT-encapsulated PLGA (PLGA-CPT) nanoparticles (NPs) on drug-metabolizing cytochrome P450 enzyme, CYP3A4. MATERIALS AND METHODS: PLGA-CPT NPs were prepared by a single emulsion-solvent evaporation method. RESULTS: Transmission electron micrography showed that the NPs had a round and regular shape with a mean diameter of 94.6±5.7 nm. An in vitro drug release study showed that CPT was continuously released for 48 h. PLGA-CPT NPs showed greater cytotoxic effects on the HepG2 cell line compared with an equal dose of free CPT. Correlation with 4-h uptake data suggested that this was due to a higher cellular uptake amount of CPT from PLGA-CPT NPs than from free CPT. PLGA-CPT NPs tended to inhibit CYP3A4 activity isolated from HepG2 cells. However, PLGA-CPT NPs had no effect on the CYP3A4 mRNA levels. Furthermore, the interaction between PLGA-CPT NPs and CYP3A4 was investigated by ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy. CONCLUSION: Taken together, the results demonstrate that CYP3A4 may be inhibited by PLGA-CPT NPs and interference with biotransformation should be considered when using NPs as drug delivery vesicles.

Apoptosis induction in K562 human myelogenous leukaemia cells is connected to the modulation of Wnt/ß-catenin signalling by BHX, a novel pyrazoline derivative.

OBJECTIVES: The goal of this study was to explore the effects of BHX on human chronic myeloid leukaemia (CML) cells and to elucidate the underlying molecular mechanism. MATERIALS AND METHODS: CML cell line K562 cells were treated with BHX. The effects of BHX on cell proliferation, apoptosis and cell cycle were detected. Subsequently, the caspase, ATP activity, Ca2+ , ROS and mitochondrial membrane potential (MMP) levels treated with various concentrations of BHX were analysed. The variation of relevant proteins and genes was detected. Further, toxicity of BHX on peripheral blood cells, bone marrow-nucleated cells (BMNC) and organ index were investigated on mice. RESULTS: Results showed that BHX suppressed K562 cell proliferation in a dose-dependent manner and induced apoptosis and G0/G1 phase arrest. BHX induced mitochondria-mediated apoptosis, which was associated with downregulation of MMP, activation of caspase-3 and caspase-9, generation of intracellular ROS and elevation of Ca2+ in K562 cells. In treated cells, ATP levels were decreased, expression of total ß-catenin, phosphorylated ß-catenin and ß-catenin in the nucleus was decreased, and expression of cell cycle-related proteins was decreased. Further analysis revealed that BHX lowered the transcriptional level of ß-catenin. Lastly, BHX treatment significantly reduced the number of white blood cells, but had no effect on BMNC and organ index. CONCLUSIONS: These findings provide further insight into the potential use of BHX as an anti-cancer agent against human leukaemia.

A pro-angiogenic degradable Mg-poly(lactic-co-glycolic acid) implant combined with rhbFGF in a rat limb ischemia model.

Site-specific controlled release of exogenous angiogenic growth factors, such as recombinant human basic fibroblast growth factor (rhbFGF), has become a promising approach to improve peripheral vascular disease. Here, we have developed an implant composed of spiral magnesium (Mg) and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The encapsulated protein could release continually for 4weeks with well preserved bioactivity. We compared the angiogenic effect produced by Mg-PLGA-rhbFGF with that of a PLGA implant loaded with rhbFGF (PLGA-rhbFGF). The incorporation of Mg in the implant raised the microclimate pH in the polymer, which preserved the stability of rhbFGF. Mg-PLGA-rhbFGF exhibited advantages over PLGA-rhbFGF implant in terms of a cytocompatibility evaluation. An in vivo angiogenesis test further confirmed the efficacy of released rhbFGF. HE, CD31 and α-SMA staining revealed that the controlled release of rhbFGF from the Mg-PLGA-rhbFGF implant was superior in promoting angiogenesis compared with that of the PLGA-rhbFGF implant. Four weeks post-implantation, the capillary density of the Mg-PLGA-rhbFGF group was significantly higher than that of the PLGA-rhbFGF, control and the normal group (p<0.05, p<0.01 and p<0.01, respectively). Furthermore, the limb blood perfusion ratios of the Mg-PLGA-rhbFGF and PLGA-rhbFGF groups were dramatically increased, at 99.1±2.9% and 80.7±3.2%, respectively, whereas the ischemic limb did not recover in the control group. The biocompatibility of the implants was also evaluated. In conclusion, Mg-PLGA-based, sustained local delivery of rhbFGF promotes post-ischemic angiogenesis and blood flow recovery. The results suggest potential therapeutic usefulness of Mg-PLGA-rhbFGF for tissue ischemia. STATEMENT OF SIGNIFICANCE: Magnesium (Mg)-based implant has been already used in patients with critical limb ischemia. Site-specific controlled release of recombinant human basic fibroblast growth factor (rhbFGF), has become a promising approach to improve peripheral vascular disease. We report here on a novel combination implant composed of spiral magnesium and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The preparation method does not involve any complex processes and results in a high encapsulation efficiency (approximately 100%). The degradation of metal Mg raise the microclimate pH in the PLGA polymer, which could well preserve the bioactivity of rhbFGF incorporated in the implant. Mg-PLGA-based, sustained local delivery of rhbFGF promotes post-ischemic angiogenesis and blood flow recovery in rat limb ischemic model. This work marks the first report for controlled release of rhbFGF in combination with metal Mg, and suggests potential therapeutic usefulness of Mg-PLGA-rhbFGF for tissue ischemia.

BHX, a novel pyrazoline derivative, inhibits breast cancer cell invasion by reversing the epithelial-mesenchymal transition and down-regulating Wnt/ß-catenin signalling.

The novel pyrazoline derivative, BHX, has recently been shown to exhibit potent anti-tumour activity by blocking the Wnt/ß-catenin signalling pathway. However, its effect on breast cancer growth and invasion are unknown. Our results show that BHX suppresses MDA-MB-231 cell viability and colony formation in a dose-dependent manner, and induces apoptosis and G0/G1 phase arrest. BHX-treated breast cancer cells showed morphological characteristics of cells undergoing apoptosis. Furthermore, BHX inhibited cell migration and invasion, which was associated with increased E-cadherin mRNA and protein expression, and down-regulation of SNAIL and vimentin. In addition, BHX induced the generation of intracellular ROS and decreased ß-catenin protein and mRNA expression. We used a mouse xenograft model to investigate the effects of BHX in vivo, where the growth of MDA-MB-231 xenografted tumours was suppressed in nude mice treated continuously with BHX for 21 days. Finally, the rat plasma concentration of BHX was measured by ultra-performance liquid-chromatography tandem mass spectrometry and the pharmacokinetic parameters of BHX were processed by non-compartmental analysis. In conclusion, BHX merits further study as a novel therapeutic small molecule for the treatment of breast cancer.

Effects of nanoparticle size on antitumor activity of 10-hydroxycamptothecin-conjugated gold nanoparticles: in vitro and in vivo studies.

Gold nanoparticles (AuNPs) have emerged as a promising anticancer drug delivery scaffold. However, some controversial points still require further investigation before clinical use. A complete understanding of how animal cells interact with drug-conjugated AuNPs of well-defined sizes remains poorly understood. In this study, we prepared a series of 10-hydroxycamptothecin (HCPT)-AuNP conjugates of different sizes and compared their cytotoxic effect in vitro and antitumor effect in vivo. Transmission electron micrographs showed that the NPs had a round, regular shape with a mean diameter of ~10, 25, and 50 nm. An in vitro drug release study showed that HCPT was continuously released for 120 hours. HCPT-AuNPs showed greater cytotoxic effects on the MDA-MB-231 cell line compared with an equal dose of free HCPT. Notably, HCPT-AuNPs of an average diameter of 50 nm (HCPT-AuNPs-50) had the greatest effect. Furthermore, administration of HCPT-AuNPs-50 showed the most tumor-suppressing activity against MDA-MB-231 tumor in mice among all treatment groups. The results indicate that AuNPs not only act as a carrier but also play an active role in mediating biological effects. This work gives important insights into the design of nanoscale delivery and therapeutic systems.

OX26 modified hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) nanoparticles: synthesis, characterization and evaluation of its brain delivery ability.

A novel nanoparticles-based brain drug delivery system made of hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) which was surface functionalized with transferrin antibody (OX26) was prepared. Hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) was synthesized, characterized and applied to prepare nanoparticles by means of double emulsion solvent evaporation technique. Transmission electron micrograph and dynamic light scattering showed that nanoparticles had a round and regular shape with a mean diameter of 170 ± 20 nm. Surface chemical composition was detected by X-ray photoelectron spectroscopy. Endomorphins, as a model drug, was encapsulated in the nanoparticles. In vitro drug release study showed that endomorphins was released continuously for 72 h. Cellular uptake study showed that the uptake of nanoparticles by the brain microvascular endothelial cells was both time- and concentration-dependant. Further uptake inhibition study indicated that the uptake of nanoparticles was via a caveolae-mediated endocytic pathway. In vivo endomorphins brain delivery ability was evaluated based upon the rat model of chronic constriction injury of sciatic nerve. OX26 modified nanoparticles had achieved better analgesic effects, compared with other groups. Thus, OX26 modified hyperbranched polyglycerol-conjugated poly(lactic-co-glycolic acid) nanoparticles may be a promising brain drug delivery carrier.