4 research outputs found
Lithocholic Acid Is an Eph-ephrin Ligand Interfering with Eph-kinase Activation
Eph-ephrin system plays a central role in a large variety of human cancers. In
fact, alterated expression and/or de-regulated function of Eph-ephrin system
promotes tumorigenesis and development of a more aggressive and metastatic
tumour phenotype. In particular EphA2 upregulation is correlated with tumour
stage and progression and the expression of EphA2 in non-trasformed cells
induces malignant transformation and confers tumorigenic potential. Based on
these evidences our aim was to identify small molecules able to modulate
EphA2-ephrinA1 activity through an ELISA-based binding screening. We identified
lithocholic acid (LCA) as a competitive and reversible ligand inhibiting
EphA2-ephrinA1 interaction (Ki = 49 µM). Since each
ephrin binds many Eph receptors, also LCA does not discriminate between
different Eph-ephrin binding suggesting an interaction with a highly conserved
region of Eph receptor family. Structurally related bile acids neither inhibited
Eph-ephrin binding nor affected Eph phosphorylation. Conversely, LCA inhibited
EphA2 phosphorylation induced by ephrinA1-Fc in PC3 and HT29 human prostate and
colon adenocarcinoma cell lines (IC50 = 48 and
66 µM, respectively) without affecting cell viability or other receptor
tyrosine-kinase (EGFR, VEGFR, IGFR1β, IRKβ) activity. LCA did not
inhibit the enzymatic kinase activity of EphA2 at 100 µM (LANCE method)
confirming to target the Eph-ephrin protein-protein interaction. Finally, LCA
inhibited cell rounding and retraction induced by EphA2 activation in PC3 cells.
In conclusion, our findings identified a hit compound useful for the development
of molecules targeting ephrin system. Moreover, as ephrin signalling is a key
player in the intestinal cell renewal, our work could provide an interesting
starting point for further investigations about the role of LCA in the
intestinal homeostasis
Photon asymmetry measurements of γ→ p→ π0p for Eγ= 320-650 MeV
High-statistics measurements of the photon asymmetry Σ for the γ→ p→ π0p reaction have been made in the center-of-mass energy range W= 1214 - 1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry results with recent cross-section measurements from Mainz to calculate the profile functions, Σˇ (= σ0Σ) , and perform a moment analysis. Comparison with calculations from the Bonn-Gatchina model shows that the precision of the data is good enough to further constrain the higher partial waves, and there is an indication of interference between the very small F-waves and the N(1520) 3 / 2 - and N(1535) 1 / 2 - resonances