Down-regulation of the AKT/GSK3β/β-catenin signalling pathway by the triterpene ursolic acid induced intrinsic apoptosis in human soft tissue sarcomas (original) (raw)
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Biophysical Journal, 2009
Sphingolipids are key lipid regulators of cell viability: ceramide is one of the key molecules in inducing programmed cell death (apoptosis), whereas other sphingolipids, such as ceramide 1-phosphate, are mitogenic. The thermotropic and structural behavior of binary systems of N-hexadecanoyl-D-erythro-ceramide (C 16 -ceramide) or N-hexadecanoyl-D-erythro-ceramide-1-phosphate (C 16 -ceramide-1-phosphate; C 16 -C1P) with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was studied with DSC and deuterium nuclear magnetic resonance ( 2 H-NMR). Partial-phase diagrams (up to a mole fraction of sphingolipids X ¼ 0.40) for both mixtures were constructed based on DSC and 2 H-NMR observations. For C 16 -ceramide-containing bilayers DSC heating scans showed already at X cer ¼ 0.025 a complex structure of the main-phase transition peak suggestive of lateral-phase separation. The transition width increased significantly upon increasing X cer , and the upper-phase boundary temperature of the mixture shifted to~65 C at X cer ¼ 0.40. The temperature range over which 2 H-NMR spectra of C 16 -ceramide/DPPC-d 62 mixtures displayed coexistence of gel and liquid crystalline domains increased from~10 for X cer ¼ 0.1 to~21 for X cer ¼ 0.4. For C16-C1P/DPPC mixtures, DSC and 2 H-NMR observations indicated that two-phase coexistence was limited to significantly narrower temperature ranges for corresponding C1P concentrations. To complement these findings, C 16 -ceramide/1-palmitoyl-2oleoyl-sn-glycero-3-phosphocholine (POPC) and C16-C1P/POPC mixtures were also studied by 2 H-NMR and fluorescence techniques. These observations indicate that DPPC and POPC bilayers are significantly less perturbed by C 16 -C1P than by C 16 -ceramide and that C 16 -C1P is miscible within DPPC bilayers at least up to X C1P ¼ 0.30.
Trans Interactions between Galactosylceramide and Cerebroside Sulfate across Apposed Bilayers
Biophysical Journal, 2000
The two glycosphingolipids galactosylceramide (GalC) and its sulfated form, cerebroside sulfate (CBS), are present at high concentrations in the multilayered myelin sheath and are involved in carbohydrate-carbohydrate interactions between the lipid headgroups. In order to study the structure of the complex of these two glycolipids by Fourier transform infrared (FTIR) spectroscopy, GalC dispersions were combined with CBS dispersions in the presence and absence of Ca2+. The FTIR spectra indicated that a strong interaction occurred between these glycolipids even in the absence of Ca2+. The interaction resulted in dehydration of the sulfate, changes in the intermolecular hydrogen bonding interactions of the sugar and other oxygens, decreased intermolecular hydrogen bonding of the amide C
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2013
We have in this study investigated the composition, structure and spectroscopical properties of multilamellar vesicles composed of a phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and up to 10 mol% of triolein (TO), a triglyceride. We found in agreement with previous results that the mixtures with 10 mol% TO spontaneously separate into two distinct phases, heavy (HF) and light (LF), with different densities and found this also to be the case for 2 and 5 mol% TO. The compositions of the two phases were investigated by quantitative lipid mass spectrometric analysis, and with this method we found that TO had a solubility maximum of about 4 mol% in the HF, whereas it was markedly up-concentrated in the LF. Electron paramagnetic resonance spectroscopy indicated POPC membranes of all tested concentrations of TO in both phases to be almost unperturbed by the presence of TO and to exist as vesicular structures containing entrapped water. Bilayer structure of the membranes was supported by small angle X-ray scattering that showed the membranes to form a lamellar phase. Fluorescence spectroscopy with the polarity sensitive dye Nile red revealed, that the LF samples with more than 5 mol% TO contained pure TO domains. These observations are consistent with an earlier MD simulation study by us and our co-workers suggesting triglycerides to be located in lens shaped, blister-like domains between the two lipid bilayer leaflets (Khandelia et al. (2010) [26]).
Applied Surface Science, 2017
Investigating the mechanism of action of drugs whose pharmaceutical activity is associated with cell membranes is fundamental to comprehending the biochemical and biophysical processes that occur on membrane surfaces. In this work, we investigated the interaction of an ester-type derivative of uridine, 3',4',6'-trimyristoyl uridine, with models for cell membranes formed by lipid monolayers at the air-water interface. For that, selected lipids have been chosen in order to mimic tumorigenic and non-tumorigenic cells. For mixed monolayers with 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2dihexadecanoyl-sn-glycero-3-phospho-L-serine (DPPS), the surface pressure-area isotherms exhibited a noticeable shift to lower areas in relation to the areas predicted for ideal mixtures, indicating a condensation of the monolayer structure. Changes in the viscoelastic properties of the interfacial film could be inferred by analyzing the compressibility modulus of the monolayer. Structural and morphological changes were also evidenced by using vibrational spectroscopy and Brewster angle microscopy, respectively, with distinctive effects on DPPC and DPPS. As conclusion we can state that the lipid composition of the monolayer modulates the interaction with this lipophilic drug, which may have important implications in understanding how this drug acts on specific sites of the cellular membrane.
Biophysical Journal, 2005
Quantitative structures of the fully hydrated fluid phases of dimyristoylphosphatidylcholine (DMPC) and dilauroylphosphatidylcholine (DLPC) were obtained at 30°C. Data for the relative form factors F(q z ) for DMPC were obtained using a combination of four methods. 1), Volumetric data provided F(0). 2), Diffuse x-ray scattering from oriented stacks of bilayers provided relative form factors jF(q z )j for high q z , 0.22 , q z , 0.8 Å ÿ1 . 3), X-ray scattering from extruded unilamellar vesicles with diameter 600 Å provided jF(q z )j for low q z , 0.1 , q z , 0.3 Å ÿ1 . 4), Previous measurements using a liquid crystallographic x-ray method provided jF(2ph/D)j for h ¼ 1 and 2 for a range of nearly fully hydrated D-spacings. The data from method 4 overlap and validate the new unilamellar vesicles data for DMPC, so method 4 is not required for DLPC or future studies. We used hybrid electron density models to obtain structural results from these form factors. Comparison of the model electron density profiles with that of gel phase DMPC provides areas per lipid A, 60.6 6 0.5 Å 2 for DMPC and 63.2 6 0.5 Å 2 for DLPC. Constraints on the model provided by volume measurements and component volumes obtained from simulations put the electron density profiles r(z) and the corresponding form factors F(q z ) on absolute scales. Various thicknesses, such as the hydrophobic thickness and the steric thickness, are obtained and compared to literature values.
Ceramide-platform formation and -induced biophysical changes in a fluid phospholipid membrane
Molecular Membrane Biology, 2006
To understand the formation and properties of ceramide-enriched domains in cell membranes, the biophysical properties of the binary system palmitoyloleoylphosphatidylcholine (POPC)/palmitoylceramide were thoroughly characterized. Diverse fluorescent probes and parameters were necessary to unravel the complexity of this apparently simple system. For the first time, a complete phase diagram is reported, characterizing the lamellar phases of these mixtures, and providing a quantitative framework integrating biophysical and biological studies. The diagram suggests that in resting cells no ceramide domains exist, but upon apoptotic stimuli, platforms may form. Moreover, our data show that 2 mol% of Cer strongly affects the POPC fluid matrix, suggesting that a small increase in Cer levels can significantly affect cell membrane properties. In this work, we also show that Cer domains, formed in conditions similar to physiological, are extremely ordered and rigid. The domains composition is estimated from the phase diagram and their large size was concluded from fluorescence resonance energy transfer. Dynamic light scattering and electron microscopy were used to characterize the system morphology, which is highly dependent on ceramide content and includes vesiculation and tubular structure formation.
Colloids and Surfaces B: Biointerfaces, 2005
The surface pressure (π)-area (A), the surface potential (V)-A and the dipole moment (µ ⊥)-A isotherms were obtained for six cerebrosides of LLC-2, LLC-2-1, LLC-2-8, LLC-2-10, LLC-2-12, and LLC-2-15, which were isolated from Linckia laevigata, and two-component monolayers of two different cerebrosides (LLC-2 and LLC-2-8) with phospholipid of dipalmitoylphosphatidylcholine (DPPC) on a subphase of 0.15 M sodium chloride solution as a function of cerebroside compositions in the two-component systems by employing the Wilhelmy method, the ionizing electrode method, and the fluorescence microscopy. The new finding was that LLC-2 showed a stable and liquid expanded type film. Four of them (LLC-2-8,-10,-12, and-15) had the phase transition from the liquid-expanded (LE) to the liquid-condensed (LC) states at 298.2 K. The apparent molar quantity changes (s γ , h γ , and u γ) on their phase transition on 0.15 M at 298.2 K were calculated. The miscibility of cerebroside and phospholipid in the two-component monolayers was examined by plotting the variation of the molecular area and the surface potential as a function of the cerebroside molar fraction (X cerebroside), using the additivity rule. From the AX cerebroside and V m-X phospholipid plots, a partial molecular surface area (PMA) and an apparent partial molecular surface potential (APSP) were determined at the discrete surface pressure. The PMA and APSP with the mole fraction were extensively discussed for the miscible systems. Judging from the two-dimensional phase diagrams, these were found to be one type, a positive azeotropic type; all the cerebrosides were miscible with DPPC. Furthermore, assuming a regular surface mixture, the Joos equation for the analysis of the collapse pressure of two-component monolayers allowed calculation of the interaction parameter (ξ) and the interaction energy (− ε) between the cerebrosides and DPPC. The miscibility of cerebroside and phospholipid components in the monolayer state was also supported by fluorescence microscopy.
Chemico-Biological Interactions, 2018
Background: PPAR-δ is a transcription factor which has crucial roles in stimulating oligodendroglial differentiation and myelination and its activation was also shown to differentiate malignant C6 glioma cells into oligodendrocytes. Objective: One of the ligands of PPAR-δ is erucic acid (EA), an edible omega-9 fatty acid consumed more by Asian populations and exists highly in Chinese womens milk. There exist epidemiological evidence that pediatric brain tumor incidence is among the lowest in the Chinese population. EA is also an ingredient of Lorenzo's oil used against adrenoleukodystrophy, a pediatric demyelinating disease. EA was inappropriately assumed as a strong cardiotoxin based on Spanish oil syndrome, caused by toxic-aniline dye refined rapeseed oil. In this study, we studied whether EA is capable to block growth of C6 glioma cells and modify cardiotoxicity of doxorubicin. Materials and Methods: We studied effects of EA on the 3-dimensional appearance of the adherent cells, soft agar colony formation and S-phase in the 3-dimensional spheroids in C6 glioma cell cultures. We also investigated the effects of EA on hepatic and cardiac toxicity of doxorubicin. Results: EA decreased in vitro growth of C6 glioma cells at therapeutically achievable concentrations. EA effects were more prominent in 3D-assays (soft agar colonies and spheroids) and induced cell fusions in monolayer cultures. EA decreased S-phase inhibitory potency of doxorubicin (DOX), yet augmented its efficacy to induce a senescent morphology (as assessed by scanning electron microscopy) in monolayer and to increase iNOS and eNOS expression in spheroids. In our study, EA reduced DOX-induced necrosis in mice heart and liver and induced healthier morphology of heart mitochondria (as assessed by transmission electron microscopy); yet intercalated disks (ID) were more disturbed with DOX+EA. Conclusions: Both the antitumor and cardiac effects of EA may associate with the cell-to-cell contact mechanisms. Combining systemic EA with intrathecal DOXchemotherapy via Ommaya reservoirs may reduce DOX concentrations in systemic circulation, hinder toxic interactions with EA and induce selective kill of glioma cells.
Bioorganic Chemistry, 2019
Biological membranes are one of the most important elements of living cells determining their permeability to the active compounds. Still, little is known about the drug-membrane interactions in terms of pharmacological properties of potential drugs. Chemoprevention based on natural compounds is becoming a strong trend in modern oncopharmacology, and p-coumaric acid (p-CoA) is one such compound with tentative anticancer activity. The microelectrophoretic mobility measurements and electrochemical impedance spectroscopy were applied to study the effects of p-CoA on electrical properties of liposomes, spherical bilayers, and human glioblastoma cell membranes. Our results demonstrated that after treatment with p-CoA, the surface charge of LBC3, LN-229 and LN-18 cell lines was significantly changed in alkaline pH solutions, but not in acidic pH solutions. In contrast, no changes in surface charge density values were registered for phosphatidylethanolamine liposomal membranes and A172 cell membranes after p-CoA treatment. The impedance data showed an increase in values of both the electrical capacitance and the electrical resistance, indicating that p-CoA can be partially inserted into the phosphatidylcholine bilayers. The MTT assay showed cell line-dependent cytotoxic effect of p-CoA. Further molecular analyses revealed the ATP depletion and gene transcription modulation, which might indicate organelle membrane-crossing potential of p-CoA. These results suggest, that changes in surface charge of membranes of living cells not only might be potential predictor of membrane permeability, but also indicate differential composition of cell membranes in various cell lines. Thus further multidirectional analyses are required to implement electrochemical methods as standard testing procedures during drug development process.