DHA/EPA-Enriched Phosphatidylcholine Suppresses Tumor Growth and Metastasis via Activating Peroxisome Proliferator-Activated Receptor γ in Lewis Lung Cancer Mice

Efficient expression of OUC-Sb-lip2 in Yarrowia lipolytica and its comprehensive utilization in the enrichment of DHA and EPA from fish oil

Lipases are widely used in the modification of functional lipids, particularly in the enrichment of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In this study, a lipase named OUC-Sb-lip2 was expressed in Yarrowia lipolytica, achieving a promising enzyme activity of 472.6 U/mL by optimizing the culture medium, notably through olive oil supplementation. A significant proportion (58.8%) of the lipase activity was located in the cells, whereas 41.2% was secreted into the supernatant. Both whole-cell and immobilized OUC-Sb-lip2 were used to enrich DHA and EPA from fish oil. The whole-cell approach increased the DHA and EPA contents to 2.59 and 2.55 times that of the original oil, respectively. Similarly, the immobilized OUC-Sb-lip2 resulted in a 2.00-fold increase in DHA and an 1.99-fold increase in EPA after a 6-h hydrolysis period. Whole cell and the immobilized OUC-Sb-lip2 retained 48.7% and 52.7% of their activity after six cycles of reuse, respectively.

The ω-3 Polyunsaturated Fatty Acid Docosahexaenoic Acid Enhances NK-Cell Antitumor Effector Functions

ω-3 polyunsaturated fatty acids (PUFA) are known to directly repress tumor development and progression. In this study, we explored whether docosahexaenoic acid (DHA), a type of ω-3 PUFA, had an immunomodulatory role in inhibiting tumor growth in immunocompetent mice. The number of natural killer (NK) cells but not the number of T or B cells was decreased by DHA supplementation in various tissues under physiologic conditions. Although the frequency and number of NK cells were comparable, IFNγ production by NK cells in both the spleen and lung was increased in DHA-supplemented mice in the mouse B16F10 melanoma tumor model. Single-cell RNA sequencing revealed that DHA promoted effector function and oxidative phosphorylation in NK cells but had no obvious effects on other immune cells. Using Rag2-/- mice and NK-cell depletion by PK136 antibody injection, we demonstrated that the suppression of B16F10 melanoma tumor growth in the lung by DHA supplementation was dependent mainly on NK cells. In vitro experiments showed that DHA directly enhanced IFNγ production, CD107a expression, and mitochondrial oxidative phosphorylation (OXPHOS) activity and slightly increased proliferator-activated receptor gamma coactivator-1α (PGC-1α) protein expression in NK cells. The PGC-1α inhibitor SR-18292 in vitro and NK cell-specific knockout of PGC-1α in mice reversed the antitumor effects of DHA. In summary, our findings broaden the current knowledge on how DHA supplementation protects against cancer growth from the perspective of immunomodulation by upregulating PGC-1α signaling-mediated mitochondrial OXPHOS activity in NK cells.

Black phosphorus quantum dots induce myocardial inflammatory responses and metabolic disorders in mice

As an ultrasmall derivative of black phosphorus (BP) sheets, BP quantum dots (BP-QDs) have been effectively used in many fields. Currently, information on the cardiotoxicity induced by BP-QDs remains limited. We aimed to evaluate BP-QD-induced cardiac toxicity in mice. Histopathological examination of heart tissue sections was performed. Transcriptome sequencing, real-time quantitative PCR (RT‒qPCR), western blotting, and enzyme-linked immunosorbent assay (ELISA) assays were used to detect the mRNA and/or protein expression of proinflammatory cytokines, nuclear factor kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-AKT), peroxisome proliferator-activated receptor gamma (PPARγ), and glucose/lipid metabolism pathway-related genes. We found that heart weight and heart/body weight index (HBI) were significantly reduced in mice after intragastric administration of 0.1 or 1 mg/kg BP-QDs for 28 days. In addition, obvious inflammatory cell infiltration and increased cardiomyocyte diameter were observed in the BP-QD-treated groups. Altered expression of proinflammatory cytokines and genes related to the NF-κB signaling pathway further confirmed that BP-QD exposure induced inflammatory responses. In addition, BP-QD treatment also affected the PI3K-AKT, PPARγ, thermogenesis, oxidative phosphorylation, and cardiac muscle contraction signaling pathways. The expression of genes related to glucose/lipid metabolism signaling pathways was dramatically affected by BP-QD exposure, and the effect was primarily mediated by the PPAR signaling pathway. Our study provides new insights into the toxicity of BP-QDs to human health.

PPARγ Modulators in Lung Cancer: Molecular Mechanisms, Clinical Prospects, and Challenges

Lung cancer is one of the most lethal malignancies worldwide. Peroxisome proliferator-activated receptor gamma (PPARγ, NR1C3) is a ligand-activated transcriptional factor that governs the expression of genes involved in glucolipid metabolism, energy homeostasis, cell differentiation, and inflammation. Multiple studies have demonstrated that PPARγ activation exerts anti-tumor effects in lung cancer through regulation of lipid metabolism, induction of apoptosis, and cell cycle arrest, as well as inhibition of invasion and migration. Interestingly, PPARγ activation may have pro-tumor effects on cells of the tumor microenvironment, especially myeloid cells. Recent clinical data has substantiated the potential of PPARγ agonists as therapeutic agents for lung cancer. Additionally, PPARγ agonists also show synergistic effects with traditional chemotherapy and radiotherapy. However, the clinical application of PPARγ agonists remains limited due to the presence of adverse side effects. Thus, further research and clinical trials are necessary to comprehensively explore the actions of PPARγ in both tumor and stromal cells and to evaluate the in vivo toxicity. This review aims to consolidate the molecular mechanism of PPARγ modulators and to discuss their clinical prospects and challenges in tackling lung cancer.

Oral Supplementation of Phosphatidylcholine Attenuates the Onset of a Diet-Induced Metabolic Dysfunction-Associated Steatohepatitis in Female C57BL/6J Mice

BACKGROUND & AIMS

Changes in phosphatidylcholine levels in the liver have been associated with the development of metabolic dysfunction-associated steatotic liver disease. Here, the effects of supplementing phosphatidylcholine on the development of early signs of metabolic dysfunction-associated steatohepatitis were assessed.

METHODS

Male and female C57BL/6J mice were fed a liquid control or a fructose-, fat-, and/or cholesterol-rich diet for 7 or 8 weeks. The diets of female mice were fortified ± phosphatidylcholine (12.5 mg/g diet). In liver tissue and portal blood, indices of liver damage, inflammation, and bacterial endotoxemia were measured. J774A.1 cells and human monocytes preincubated with phosphatidylcholine (0.38 mmol/L) were challenged with lipopolysaccharide (50-100 ng/mL) ± the peroxisome proliferator-activated receptor γ (PPARγ) activator pioglitazone (10 μmol/L) or ± a liver receptor homolog 1 (LRH-1) antagonist 1-(3'-[1-(2-[4-morpholinyl]ethyl)-1H-pyrazol-3-yl]-3-biphenylyl)ethanon (1-10 μmol/L).

RESULTS

In fructose-, fat-, and/or cholesterol-rich diet-fed mice the development of fatty liver and the beginning of inflammation were associated with significantly lower hepatic phosphatidylcholine levels when compared with controls. Supplementing phosphatidylcholine significantly attenuated the development of fatty liver and inflammation, being associated with protection against the induction of PPARγ2, and activation of nuclear factor of κ light polypeptide gene enhancer in B-cell inhibitor α whereas Lrh1 expression was unchanged. The protective effects of phosphatidylcholine on the lipopolysaccharide-induced activation of J774A.1 cells and human monocytes were attenuated significantly by the PPARγ activator pioglitazone and the LRH-1 antagonist.

CONCLUSIONS

Our data suggest that phosphatidylcholine levels in the liver are lower in early metabolic dysfunction-associated steatohepatitis in mice and that supplementation of phosphatidylcholine can diminish the development of metabolic dysfunction-associated steatotic liver disease through mechanisms involving LRH-1/PPARγ2/ nuclear factor κ-light-chain enhancer of activated B-cell signaling.

DHA supplementation and pregnancy complications

Docosahexaenoic acid (DHA) supplementation is recommended for women during pregnancy because of its neurological, visual, and cognitive effects. Previous studies have suggested that DHA supplementation during pregnancy may prevent and treat certain pregnancy complications. However, there are contradictions in the current related studies, and the specific mechanism by which DHA acts remains unclear. This review summarizes the research on the relationship between DHA intake during pregnancy and preeclampsia, gestational diabetes mellitus, preterm birth, intrauterine growth restriction, and postpartum depression. Furthermore, we explore the impact of DHA intake during pregnancy on the prediction, prevention, and treatment of pregnancy complications as well as its impact on offspring neurodevelopment. Our results suggest that there is limited and controversial evidence for the protective effect of DHA intake on pregnancy complications, with the exception of preterm birth and gestational diabetes mellitus. However, additional DHA supplementation may improve long-term neurodevelopmental outcomes in the offspring of women with pregnancy complications.

Lysophosphatidylcholine-DHA Specifically Induces Cytotoxic Effects of the MDA-MB-231 Human Breast Cancer Cell Line In Vitro-Comparative Effects with Other Lipids Containing DHA

Docosahexaenoic acid (DHA, C22:6 ω-3) is a dietary polyunsaturated fatty acid that has an important role in human health. Epidemiological studies linked a high intake of DHA to a reduced risk of certain cancers. Recently, attention focused on how the lipid carrier in which DHA is delivered, i.e., esterified on acylglycerols, phospholipids, or free, affects its biological effects. However, studies comparing the effects of these different forms for DHA supply to cancer cells in vitro are limited. In this study, the effect of free DHA and five lipids carrying one to three DHA chains (LPC-DHA, PC-DHA, MAG-DHA, DAG-DHA and TAG-DHA) on the viability of the MDA-MB-231 breast cancer cell line was compared. Our results revealed a strong structure-function relationship of DHA-carrying lipids on the viability of MDA-MB-231 cells. Glycerophosphocholine-based lipids are the most effective DHA carriers in reducing the viability of MDA-MB-231 cells, with LPC-DHA being more effective (IC₅₀ = 23.7 µM) than PC-DHA (IC₅₀ = 67 µM). The other tested lipids are less toxic (MAG-DHA, free DHA) or even not toxic (DAG-DHA, TAG-DHA) under our conditions. Investigating the mechanism of cell death induced by LPC-DHA revealed increased oxidative stress and membrane cell damage.

Lipid biomarkers that reflect postoperative recurrence risk in lung cancer patients who smoke: a case-control study

BACKGROUND

The risk of postoperative recurrence is higher in lung cancer patients who smoke than non-smokers. However, objective evaluation of the postoperative recurrence risk is difficult using conventional pathological prognostic factors because of their lack of reproducibility. Consequently, novel objective biomarkers that reflect postoperative risk in lung cancer patients who smoke must be identified. Because cigarette smoking and oncogenesis alter lipid metabolism in lung tissue, we hypothesized that the lipid profiles in lung cancer tissues are influenced by cigarette smoking and can reflect the postoperative recurrence risk in smoking lung cancer patients. This study aimed to identify lipid biomarkers that reflect the smoking status and the postoperative recurrence risk.

METHODS

Primary tumor tissues of lung adenocarcinoma (ADC) (n = 26) and squamous cell carcinoma (SQCC) (n = 18) obtained from surgery were assigned to subgroups according to the patient's smoking status. The ADC cohort was divided into never smoker and smoker groups, while the SQCC cohort was divided into moderate smoker and heavy smoker groups. Extracted lipids from the tumor tissues were subjected to liquid chromatography-tandem mass spectrometry analysis. Lipids that were influenced by smoking status and reflected postoperative recurrence and pathological prognostic factors were screened.

RESULTS

Two and 12 lipid peaks in the ADC and SQCC cohorts showed a significant positive correlation with the Brinkman index, respectively. Among them, in the ADC cohort, a higher lipid level consisted of three phosphatidylcholine (PC) isomers, PC (14:0_18:2), PC (16:1_16:1), and PC (16:0_16:2), was associated with a shorter recurrence free period (RFP) and a greater likelihoods of progressed T-factor (≥ pT2) and pleural invasion. In the SQCC cohort, a lower m/z 736.5276 level was associated with shorter RFP and greater likelihood of recurrence.

CONCLUSIONS

From our data, we propose three PC isomers, PC (14:0_18:2), PC (16:1_16:1), and PC (16:0_16:2), and a lipid peak of m/z 736.5276 as novel candidate biomarkers for postoperative recurrence risk in lung ADC and SQCC patients who are smokers.

DHA- and EPA-Enriched Phosphatidylcholine Suppress Human Lung Carcinoma 95D Cells Metastasis via Activating the Peroxisome Proliferator-Activated Receptor γ

The antineoplastic effects of docosahexaenoic acid-containing phosphatidylcholine (DHA-PC) and eicosapentaenoic acid-containing phosphatidylcholine (EPA-PC) were explored, and their underlying mechanisms in the human lung carcinoma 95D cells (95D cells) were investigated. After treatment of 95D cells with DHA-PC or EPA-PC, cell biological behaviors such as growth, adhesion, migration, and invasion were studied. Immunofluorescence and western blotting were carried out to assess underlying molecular mechanisms. Results showed that 95D cells proliferation and adherence in the DHA-PC or EPA-PC group were drastically inhibited than the control group. DHA-PC and EPA-PC suppressed the migration and invasion of 95D cells by disrupting intracellular F-actin, which drives cell movement. The protein expression of PPARγ was induced versus the control group. Furthermore, critical factors related to invasion, including matrix metallopeptidase 9 (MMP9), heparanase (Hpa), and vascular endothelial growth factor (VEGF), were drastically downregulated through the PPARγ/NF-κB signaling pathway. C-X-C chemokine receptor type 4 (CXCR4) and cofilin were significantly suppressed via DHA-PC and EPA-PC through the PPARγ/phosphatase and tensin homolog (PTEN)/serine-threonine protein kinase (AKT) signaling pathway. DHA-PC and EPA-PC reversed the PPARγ antagonist GW9662-induced reduction of 95D cells in migration and invasion capacity, suggesting that PPARγ was directly involved in the anti-metastasis efficacy of DHA-PC and EPA-PC. In conclusion, DHA-PC and EPA-PC have great potential for cancer therapy, and the antineoplastic effects involve the activation of PPARγ. EPA-PC showed more pronounced antineoplastic effects than DHA-PC, possibly due to the more robust activation of PPARγ by EPA-PC.

The association between circulating docosahexaenoic acid and lung cancer: A Mendelian randomization study

BACKGROUND

Lung cancer is a malignant tumor with a high incidence, it is vital to identify modifiable and avoidable risk factors for primary prevention, which can significantly lower the risk of cancer by preventing exposure to hazards and altering risky behavior. Some observational studies suggest that an increase in docosahexaenoic acid (DHA) consumption can reduce lung cancer risk. However, interpretation of these observational findings is difficult due to residual confounding or reverse causality. To evaluate the link between DHA and lung cancer, we have undertaken this analysis to examine the causal association between DHA and the risk of lung cancer using a two-sample Mendelian randomization (MR) framework.

METHODS

We performed a two-sample MR analysis to evaluate the causal effect of plasma DHA levels on lung cancer risk. For the exposure data, we extracted genetic variants as instrumental variables (IVs) that are strongly associated with DHA from a large-scale genome-wide association study (GWAS). We obtained the corresponding effect estimates for IVs on the risk of lung cancer with 11,348 cases and 15,861 controls. Finally, we applied Mendelian randomization analysis to obtain preliminary MR results and performed sensitivity analyses to verify the robustness of our results.

RESULTS

According to the primary MR estimates and further sensitivity analyses, a higher serum DHA level was associated with a higher risk of lung cancer [OR = 1.159, 95% CI (1.04-1.30), P = 0.01]. For lung adenocarcinoma, the results also showed a close correlation between the DHA level and lung adenocarcinoma [OR = 1.277, 95% CI (1.09-1.50), P = 0.003], but it was not statistically significant for squamous cell carcinoma [OR = 1.071, 95% CI (0.89-1.29), P = 0.467].

CONCLUSIONS

Our study revealed that plasma DHA is positively associated with the risk of lung cancer overall, especially for lung adenocarcinoma. This study provides new information to develop dietary guidelines for primary lung cancer prevention.

Comparative Study of Docosahexaenoic Acid with Different Molecular Forms for Promoting Apoptosis of the 95D Non-Small-Cell Lung Cancer Cells in a PPARγ-Dependent Manner

Cancer is a leading cause of death in worldwide. Growing evidence has shown that docosahexaenoic acid (DHA) has ameliorative effects on cancer. However, the effects of DHA-enriched phosphatidylcholine (DHA-PC) and efficacy differences between DHA-PC, DHA-triglyceride (DHA-TG), and DHA- ethyl esters (DHA-EE) on cancer cells had not been studied. In this study, 95D lung cancer cells in vitro were used to determine the effects and underlying mechanisms of DHA with different molecular forms. The results showed that DHA-PC and DHA-TG treatment significantly inhibited the growth of 95D cells by 53.7% and 33.8%, whereas DHA-EE had no significantly effect. Morphological analysis showed that DHA-PC and DHA-TG prompted promoted cell contraction, increased concentration of cell heterochromatin, vacuolization of cytoplasm, and edema of endoplasmic reticulum and mitochondria. TUNEL and AO/EB staining indicated that both DHA-PC and DHA-TG promoted cell apoptosis, in which DHA-PC performed better than DHA-TG. Mechanistically, DHA-PC and DHA-TG treatment up-regulated the PPARγ and RXRα signal, inhibited the expression of NF-κB and Bcl-2, and enhanced the expression of Bax and caspase-3, thereby promoting cell apoptosis. In conclusion, DHA-PC exerted superior effects to DHA-TG and DHA-EE in promoting apoptosis in 95D non-small-cell lung cancer cells. These data provide new evidence for the application of DHA in treatment of cancer.

Elevated serum phosphatidylcholine (16:1/22:6) levels promoted by fish oil and vitamin D3 are highly correlated with biomarkers of non-alcoholic fatty liver disease in Chinese subjects

Phosphatidylcholine (16:1/22:6) was associated with improving inflammation and lipid metabolism.

Short-term supplementation of DHA-enriched phospholipids attenuates the nephrotoxicity of cisplatin without compromising its antitumor activity in mice

Cisplatin is one of the most effective chemotherapeutic agents used for the treatment of a wide variety of cancers. However, cisplatin has been associated with nephrotoxicity, which limits its application in clinical treatment. Various studies have indicated the protective effect of phospholipids against acute kidney injury. However, no study has focused on the different effects of phospholipids with different fatty acids on cisplatin-induced nephrotoxicity and on the combined effects of phospholipids and cisplatin in tumour-bearing mice. In the present study, the potential renoprotective effects of phospholipids with different fatty acids against cisplatin-induced nephrotoxicity were investigated by determining the serum biochemical index, renal histopathological changes, protein expression level and oxidative stress. The results showed that docosahexaenoic acid-enriched phospholipids (DHA-PL) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) could alleviate cisplatin-induced nephrotoxicity by regulating the caspase signaling pathway, the SIRT1/PGC1α pathway, and the MAPK (mitogen-activated protein kinase) signaling pathway and by inhibiting oxidative stress. In particular, DHA-PL exhibited a better inhibitory effect on oxidative stress and apoptosis compared to EPA-PL. Furthermore, DHA-PL exhibited an additional effect with cisplatin on the survival of ascitic tumor-bearing mice. These findings suggested that DHA-PL are one kind of promising supplement for the alleviation of cisplatin-induced nephrotoxicity without compromising its antitumor activity.

Biological action of docosahexaenoic acid in a 3D tissue-engineered psoriatic skin model: Focus on the PPAR signaling pathway

N-3 polyunsaturated fatty acids (n-3 PUFAs), and in particular docosahexaenoic acid (DHA), have many beneficial metabolic effects, including reducing epidermal thickness in patients with psoriasis. The positive impacts of DHA in psoriasis could be mediated by its interactions with the PPAR signaling pathway, as well as by its secretion of anti-inflammatory bioactive metabolites, but the detailed metabolism is still not understood. In the present study, we evaluated the influence of DHA on the main features of psoriasis and its effects on the PPAR signaling pathway, in a psoriatic in vitro skin model. Healthy and psoriatic skin substitutes were produced according to the tissue-engineered self-assembly method, using culture media supplemented with 10 μM of DHA. The presence of DHA led to a reduction in the abnormal cell differentiation of psoriatic keratinocytes, seen in the increased expression of filaggrin and keratin 10. DHA was incorporated into the membrane phospholipids of the epidermis and transformed principally into eicosapentaenoic acid (EPA). Furthermore, the addition of DHA into the culture medium led to a decrease in the levels of lipid mediators derived from n-6 PUFAs, mainly prostaglandin E₂ (PGE₂) and 12-hydroxyeicosatetraenoic acid (12-HETE). Finally, DHA supplementation rebalanced the expression of PPAR receptors and caused a decrease in the secretion of TNF-α. Altogether, our results show that DHA possesses the ability to attenuate the psoriatic characteristics of psoriatic skin substitutes, mostly by restoring epidermal cell differentiation and proliferation, as well as by reducing inflammation.