Sulfated Polysaccharides from Macroalgae Are Potent Dual Inhibitors of Human ATP-Hydrolyzing Ectonucleotidases NPP1 and CD39

Extracellular ATP mediates proinflammatory and antiproliferative effects via activation of P2 nucleotide receptors. In contrast, its metabolite, the nucleoside adenosine, is strongly immunosuppressive and enhances tumor proliferation and metastasis. The conversion of ATP to adenosine is catalyzed by ectonucleotidases, which are expressed on immune cells and typically upregulated on tumor cells. In the present study, we identified sulfopolysaccharides from brown and red sea algae to act as potent dual inhibitors of the main ATP-hydrolyzing ectoenzymes, ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1) and ecto-nucleoside triphosphate diphosphohydrolase-1 (NTPDase1, CD39), showing nano- to picomolar potency and displaying a non-competitive mechanism of inhibition. We showed that one of the sulfopolysaccharides tested as a representative example reduced adenosine formation at the surface of the human glioblastoma cell line U87 in a concentration-dependent manner. These natural products represent the most potent inhibitors of extracellular ATP hydrolysis known to date and have potential as novel therapeutics for the immunotherapy of cancer

1-methylnicotinamide and its structural analog 1,4-dimethylpyridine for the prevention of cancer metastasis

Background: 1-methylnicotinamide (1-MNA), an endogenous metabolite of nicotinamide, has recently gained interest due to its anti-inflammatory and anti-thrombotic activities linked to the COX-2/PGI2 pathway. Given the previously reported anti-metastatic activity of prostacyclin (PGI2), we aimed to assess the effects of 1-MNA and its structurally related analog, 1,4-dimethylpyridine (1,4-DMP), in the prevention of cancer metastasis. Methods: All the studies on the anti-tumor and anti-metastatic activity of 1-MNA and 1,4-DMP were conducted using the model of murine mammary gland cancer (4T1) transplanted either orthotopically or intravenously into female BALB/c mouse. Additionally, the effect of the investigated molecules on cancer cell-induced angiogenesis was estimated using the matrigel plug assay utilizing 4T1 cells as a source of pro-angiogenic factors. Results: Neither 1-MNA nor 1,4-DMP, when given in a monotherapy of metastatic cancer, influenced the growth of 4T1 primary tumors transplanted orthotopically; however, both compounds tended to inhibit 4T1 metastases formation in lungs of mice that were orthotopically or intravenously inoculated with 4T1 or 4T1-luc2-tdTomato cells, respectively. Additionally, while 1-MNA enhanced tumor vasculature formation and markedly increased PGI2 generation, 1,4-DMP did not have such an effect. The anti-metastatic activity of 1-MNA and 1,4-DMP was further confirmed when both agents were applied with a cytostatic drug in a combined treatment of 4T1 murine mammary gland cancer what resulted in up to 80 % diminution of lung metastases formation. Conclusions: The results of the studies presented below indicate that 1-MNA and its structural analog 1,4-DMP prevent metastasis and might be beneficially implemented into the treatment of metastatic breast cancer to ensure a comprehensive strategy of metastasis control

Characterization of the interactions between various hexadecylmannoside-phospholipid model membranes with the lectin Concanavalin A

The specific interaction of Concanavalin A (ConA) with glycolipid-containing model membranes was investigated using (a) surface pressure-time (Pi-t) curves, (b) epifluorescence microscopy connected to a film balance, (c) atomic force microscopy (AFM) of the monofilms after Langmuir-Blodgett (LB) transfer and (d) quartz crystal microbalance (QCMB) weight-quantification of the adhered protein on the glycolipid model membrane. The adsorption of ConA on a model membrane was mannose-specific and concentration-dependent in the range 1-50% (1% was the lower detection limit, whereas above 30% saturation began). Adsorption kinetics was followed by QCMB and Pi-t measurements. Saturation was reached after 1 h. Hydrophilic spacers were introduced between the alkyl chain and the mannose headgroup of the ConA ligands. The quantity of specific ConA-adhesion increased with spacer length and also the adhesion kinetics was accelerated using protruding ligands. With AFM it was possible to detect morphological differences of mixed hexadecylmannoside-1,2-distearyl-sn-glycero-3-phosphocholine (DSPC) films in dependence on spacer length of the glycolipid before and after molecular contact with ConA

Characterization of the interactions between various hexadecylmannoside-phospholipid model membranes with the lectin Concanavalin A

The specific interaction of Concanavalin A (ConA) with glycolipid-containing model membranes was investigated using (a) surface pressure-time (Pi-t) curves, (b) epifluorescence microscopy connected to a film balance, (c) atomic force microscopy (AFM) of the monofilms after Langmuir-Blodgett (LB) transfer and (d) quartz crystal microbalance (QCMB) weight-quantification of the adhered protein on the glycolipid model membrane. The adsorption of ConA on a model membrane was mannose-specific and concentration-dependent in the range 1-50% (1% was the lower detection limit, whereas above 30% saturation began). Adsorption kinetics was followed by QCMB and Pi-t measurements. Saturation was reached after 1 h. Hydrophilic spacers were introduced between the alkyl chain and the mannose headgroup of the ConA ligands. The quantity of specific ConA-adhesion increased with spacer length and also the adhesion kinetics was accelerated using protruding ligands. With AFM it was possible to detect morphological differences of mixed hexadecylmannoside-1,2-distearyl-sn-glycero-3-phosphocholine (DSPC) films in dependence on spacer length of the glycolipid before and after molecular contact with ConA

The relation between human hair follicle density and touch perception

Unmyelinated low threshold C-tactile fibers moderate pleasant aspects of touch. These fibers respond optimally to stroking stimulation of the skin with slow velocities (1-10 cm/s). Low threshold mechanoreceptors are arranged around hair follicles in rodent skin. If valid also in humans, hair follicle density (HFD) may relate to the perceived pleasantness of stroking tactile stimulation. We conducted two studies that examined the relation between HFD and affective touch perception in humans. In total, 138 healthy volunteers were stroked on the forearm and rated the pleasantness and intensity. Stimulation was performed by a robotic tactile stimulator delivering C-tactile optimal (1, 3, 10 cm/s) and non-optimal (0.1, 0.3, 30 cm/s) stroking velocities. Additionally, a measure of discriminative touch was applied in study 2. HFD of the same forearm was determined using the Cyanoacrylate Skin Stripping Method (CSSM), which we validated in a pretest. Women had higher HFD than men, which was explained by body size and weight. Furthermore, women rated affective touch stimuli as more pleasant and had higher tactile acuity. Depilation did not affect touch perception. A weak relationship was found between the C-tactile specific aspects of affective touch perception and HFD, and the hypothesis of HFD relating to pleasant aspects of stroking only received weak support.Funding Agencies|German Research Foundation (DFG) [CR 479/1-1]; Swedish Research Council; German Research Foundation; Open Access Publication Funds of the TU Dresden</p

Model membrane studies for characterization of different antibiotic activities of lipopeptides from Pseudomonas

Lipopeptides (LPs) are a structurally diverse class of amphipathic natural products that were in the past mainly known for their surfactant properties. However, the recent discovery of their antimicrobial and cytotoxic bioactivities have fueled and renewed the interest in this compound class. Propelled by the antimicrobial potential of this compound class, in this study a range of six underinvestigated LPs from Pseudomonads were examined with respect to their antibiotic activities towards bacteria. The assays revealed that only the glycosylated lipodipeptide SB-253514, produced by Pseudomonas strain SH-C52, showed significant antibacterial activity. Since the bioactivity of LPs is commonly attributed to membrane interactions, we analyzed the molecular interactions between the LPs and bacteria-like lipid model membranes in more detail via complementary biophysical approaches. Application of the quartz crystal microbalance (QCM) showed that all LPs possess a high binding affinity towards the model membranes. Despite their similar membrane affinity, monolayer studies displayed different tendencies of LPs to incorporate into the membrane. The degree of membrane incorporation could be correlated with specific structural features of the investigated LPs, such as distance between the peptidic macrocycle and the fatty acid, but did not fully reflect their respective antibacterial activity. Cyclic voltammetry (CV) experiments further demonstrated that SB-253514 showed no membrane permeabilization effects at inhibitory concentrations. Collectively, these results suggests that the antibacterial activity of SB-253514 cannot be explained by an unspecific detergent-like mechanism generally proposed for amphiphilic molecules but instead appears to occur via a defined structural target