Utilization of extracellular lipids by HT29/219 cancer cells in culture

Medicinal Activities and Nanomedicine Delivery Strategies for Brucea javanica Oil and Its Molecular Components

Brucea javanica oil (BJO) is widely used in traditional Chinese medicine to treat various types of cancer and inflammatory diseases. There is significant interest in understanding the medicinal activities of BJO and its molecular components, especially quassinoids, and in exploring how they can be incorporated into nanomedicine delivery strategies for improved application prospects. Herein, we cover the latest progress in developing different classes of drug delivery vehicles, including nanoemulsions, liposomes, nanostructured lipid carriers, and spongosomes, to encapsulate BJO and purified quassinoids. An introduction to the composition and medicinal activities of BJO and its molecular components, including quassinoids and fatty acids, is first provided. Application examples involving each type of drug delivery vehicle are then critically presented. Future opportunities for nanomedicine delivery strategies in the field are also discussed and considered within the context of translational medicine needs and drug development processes.

Alpha linolenic acid and oleic acid additively down-regulate malignant potential and positively cross-regulate AMPK/S6 axis in OE19 and OE33 esophageal cancer cells

OBJECTIVE

Both oleic acid (OA) and alpha-linolenic acid (ALA) have been proposed to down-regulate cell proliferation of prostate, breast, and bladder cancer cells. However, direct evidence that OA and/or ALA suppresses to the development of esophageal cancer has not been studied. Also, no previous studies have evaluated how OA and/or ALA regulates malignant potential (cell proliferation, migration, colony formation and adhesion) and intracellular signaling pathways, and whether their effects might be synergistic and/or additive in esophageal cancer cells has not yet been elucidated.

MATERIALS/METHODS

We conducted in vitro studies and evaluated whether OA and ALA alone or in combination may regulate malignant potential in OE19 and OE33 esophageal cancer cell lines.

RESULTS

Both OA and ALA significantly down-regulated cell proliferation, adhesion and/or migration. OA and/or ALA did not change the number of colonies but decrease colony sizes when compared to control. Also, we observed that OA and/or ALA positively cross-regulates the expression levels of AMPK/S6 axis. Moreover, OA and ALA up-regulated tumor suppressor genes (p53, p21, and p27) and these effects are abolished by AMPK siRNA administration. Importantly, we observed that these effects are additively regulated by OA and ALA in combination when compared to control in OE19 and OE33 esophageal cancer cell lines.

CONCLUSIONS

Our novel mechanistic studies provide evidence for an important role for OA and ALA in esophageal cancer, and suggest that OA and/or ALA might be useful agents in the management or chemoprevention of esophageal cancer.

Serum-induced differentiation of human meibomian gland epithelial cells

PURPOSE

We hypothesize that culturing immortalized human meibomian gland epithelial cells in serum-containing medium will induce their differentiation. The purpose of this investigation was to begin to test our hypothesis, and explore the impact of serum on gene expression and lipid accumulation in human meibomian gland epithelial cells.

METHODS

Immortalized and primary human meibomian gland epithelial cells were cultured in the presence or absence of serum. Cells were evaluated for lysosome and lipid accumulation, polar and neutral lipid profiles, and gene expression.

RESULTS

Our results support our hypothesis that serum stimulates the differentiation of human meibomian gland epithelial cells. This serum-induced effect is associated with a significant increase in the expression of genes linked to cell differentiation, epithelium development, the endoplasmic reticulum, Golgi apparatus, vesicles, and lysosomes, and a significant decrease in gene activity related to the cell cycle, mitochondria, ribosomes, and translation. These cellular responses are accompanied by an accumulation of lipids within lysosomes, as well as alterations in the fatty acid content of polar and nonpolar lipids. Of particular importance, our results show that the molecular and biochemical changes of immortalized human meibomian gland epithelial cells during differentiation are analogous to those of primary cells.

CONCLUSIONS

Overall, our findings indicate that immortalized human meibomian gland epithelial cells may serve as an ideal preclinical model to identify factors that control cellular differentiation in the meibomian gland.

Inhibition of ATP citrate lyase induces triglyceride accumulation with altered fatty acid composition in cancer cells

De novo lipogenesis is activated in most cancers and several lipogenic enzymes have been implicated as therapeutic targets. Here, we demonstrate a novel function of the lipogenic enzyme, ATP citrate lyase (ACLY), in lipid metabolism in cancer cells. ACLY depletion by small interfering RNAs caused growth suppression and/or apoptosis in a subset of cancer cell lines. To investigate the effect of ACLY inhibition on lipid metabolism, metabolome and transcriptome analysis was performed. ACLY depletion blocks the fatty acid chain elongation from C16 to C18 in triglyceride (TG), but not in other lipid classes. Meanwhile, wild-type ACLY overexpression enhanced fatty acid elongation of TG, whereas an inactive mutant ACLY did not change it. ACLY depletion-mediated blockade of fatty acid elongation was coincident with downregulation of long-chain fatty acid elongase ELOVL6, which resides in endoplasmic reticulum (ER). Paradoxically, ACLY depletion-mediated growth suppression was associated with TG accumulation. ACLY depletion downregulated the expression of carnitine palmitoyltransferase 1A, which is a mitochondrial fatty acid transporter. Consistent with this finding, metabolome analysis revealed that ACLY positively regulates the carnitine system, which plays as an essential cofactor for fatty acid transport across mitochondrial membrane. AICAR, an activator of mitochondrial fatty acid oxidation (FAO), significantly reduced ACLY depletion-mediated TG accumulation. These data indicate that inhibition of ACLY might affect both fatty acid elongation in ER and FAO in mitochondria, thereby explaining the TG accumulation with altered fatty acid composition. This phenotype may be a hallmark of growth suppression mediated by ACLY inhibition.

Comparison of metabolite profiles in U87 glioma cells and mesenchymal stem cells

Gas chromatography-mass spectrometry (GC-MS) profiles were generated from U87 glioma cells and human mesenchymal stem cells (hMSC). 37 metabolites representing glycolysis intermediates, TCA cycle metabolites, amino acids and lipids were selected for a detailed analysis. The concentrations of these metabolites were compared and Pearson correlation coefficients were used to calculate the relationship between pairs of metabolites. Metabolite profiles and correlation patterns differ significantly between the two cell lines. These profiles can be considered as a signature of the underlying biochemical system and provide snap-shots of the metabolism in mesenchymal stem cells and tumor cells.

A 13C nuclear magnetic resonance study of free fatty acid incorporation in acylated lipids in differentiating preadipocytes

To understand the role of free fatty acid (FFA) incorporation in the accumulation of lipids in the adipocyte and ultimately in the development of obesity, 13C nuclear magnetic resonance was used to study lipid metabolism in differentiating preadipocytes. The incorporation of 13C=O-labeled FFA into cellular lipids in primary cultured rat preadipocytes and 3T3L1 preadipocytes at different stages of differentiation was monitored by the 13C carbonyl chemical shift. Significant incorporation of palmitic acid into phosphatidylcholine in both the alpha and beta acyl chain positions was found in cells at early stages of differentiation. At later differentiation stages or after extended incubation periods, most of the 13C=O signals were found in the triacylglycerol (TG) molecules. Unsaturated 13C=O-labeled acyl chains were detected in the TG molecules when cells were incubated with saturated 13C=O-labeled FFA, indicating that intracellular dehydrogenation had occurred in the 13C=O-labeled palmitoyl chain. By using 13C-labeled methyl myristate as an internal intensity reference, incorporation of 13C FFA into each acyl chain position of the major intracellular lipids was determined quantitatively.

Comparison of linoleic acid and eicosapentaenoic acid incorporation into human breast cancer cells

To gain some insight into the mechanisms involved in the opposing effects of linoleic acid (LA) and eicosapentaenoic acid (EPA) on the growth and invasiveness of MDA-MB-435 human breast cancer cells, the dynamics of the uptake by cells and the incorporation of [14C]LA and [14C]EPA into major lipid and phospholipid pools, as well as the effects of unlabeled EPA or LA on the uptake and distribution of [14C]LA or [14C]EPA, respectively, were examined. Cells were exposed to [14C]LA (1.28 micrograms/mL) or [14C]EPA (1.0 micrograms/mL) and unlabeled EPA or LA, respectively, at 0, 1, 4 and 16 micrograms/mL for 24 h in serum-free media. The uptake of each fatty acid (FA) was linear over time and was not affected by the presence of the opposing FA. For both FA, 80-90% was incorporated into the phospholipid fraction with the remaining 10-20% in neutral lipids. The relative distribution profile of [14C]LA among the phospholipid classes indicated a preferential incorporation into phosphatidylcholine (65%), whereas [14C]EPA was mostly found in phosphatidylethanolamine (58%). In the presence of unlabeled EPA or LA at various concentrations, corresponding dose-dependent shifts of [14C]LA or [14C]EPA from the phospholipid to the neutral lipid pool were noted, which did not alter the relative distribution of the FA among the phospholipid classes. Exogenous exposure to EPA or LA increased its content in membrane phospholipids while concurrently decreasing LA or EPA content, respectively, in a dose-dependent manner. Arachidonic acid content of membrane phospholipids remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)