Objective To investigate the interactions between melanoma-derived exosomes and the microenvironment.Methods The exosomes were isolated from the culture medium of mouse melanoma cells and then co-cuhured with mesenchymal stromal cells (MSC) after identification.Immunofluorescence assay was performed to observe the exosomes engulfed by MSC.CCK-8 and transwell assays were used to evaluate the proliferation and migration of MSC.Effects of the exosomes on the expression of α-smooth muscle actin (α-SMA) in MSC were analyzed by Western blot.Results Co-culture of MSC with melanoma cell-derived exosomes enhanced the proliferation and migration of MSC as well as the expression of α-SMA.All of the changes mediated by the exosomes could be blocked by using the inhibitor of TGF-β receptor.Conclusion Melanoma cell-derived exosomes enhanced the proliferation and migration of MSC as well as the expression of α-SMA through TGF-β signaling pathway,which provided an advantageous microenvironment for melanoma progression.

To investigate the neuroprotective effect and possible mechanism of masitinib on cerebral ischemia-reperfusion injury in rats, healthy adult male Sprague-Dawley rats were divided into sham group (n = 12), model group (n = 12), masitinib low dosage group (n = 12), masitinib middle dosage group (n = 12), and masitinib high dosage group (n = 12). All rats was subjected to middle cerebral artery occlusion (MCAO) for two hours and reperfusion except sham group, and received treatment twice per day for 7 days once reperfusion started.Neurological score, infarct volume, and brain water content were detected; some autophagic markers, apoptotic and inflammatory cytokines were evaluated by Western blot and PCR after 7 d of reperfusion. Treatment with masitinib significantly ameliorated neurologic deficit, infarct volume and brain water after I/R injury. Masitinib also decreased the ratio of LC3II/I and the expression of Beclin-1 and increased the expression of p62 in the brain tissues of rats with I/R injury.Furthermore, it could inhibit apoptosis-related proteins and NF-κB expression. Masitinib could relieve the cerebral ischemia-reperfusion injury in rats through inhibiting autophagy and apoptosis.

Uch37 is a de-ubiquitinating enzyme that is activated by Rpn13 and involved in the proteasomal degradation of proteins. The full-length Uch37 was shown to exhibit low iso-peptidase activity and is thought to be auto-inhibited. Structural comparisons revealed that within a homo-dimer of Uch37, each of the catalytic domains was blocking the other's ubiquitin (Ub)-binding site. This blockage likely prevented Ub from entering the active site of Uch37 and might form the basis of auto-inhibition. To understand the mode of auto-inhibition clearly and shed light on the activation mechanism of Uch37 by Rpn13, we investigated the Uch37-Rpn13 complex using a combination of mutagenesis, biochemical, NMR, and small-angle X-ray scattering (SAXS) techniques. Our results also proved that Uch37 oligomerized in solution and had very low activity against the fluorogenic substrate ubiquitin-7-amino-4-methylcoumarin (Ub-AMC) of de-ubiquitinating enzymes. Uch37Δ(Hb,Hc,KEKE), a truncation removal of the C-terminal extension region (residues 256-329) converted oligomeric Uch37 into a monomeric form that exhibited iso-peptidase activity comparable to that of a truncation-containing the Uch37 catalytic domain only. We also demonstrated that Rpn13C (Rpn13 residues 270-407) could disrupt the oligomerization of Uch37 by sequestering Uch37 and forming a Uch37-Rpn13 complex. Uch37 was activated in such a complex, exhibiting 12-fold-higher activity than Uch37 alone. Time-resolved SAXS (TR-SAXS) and FRET experiments supported the proposed mode of auto-inhibition and the activation mechanism of Uch37 by Rpn13. Rpn13 activated Uch37 by forming a 1:1 stoichiometric complex in which the active site of Uch37 was accessible to Ub.
Binding Sites ; Catalytic Domain ; Chromatography, Gel ; Crystallography, X-Ray ; Humans ; Membrane Glycoproteins ; chemistry ; genetics ; metabolism ; Nuclear Magnetic Resonance, Biomolecular ; Protein Binding ; Protein Conformation ; Protein Multimerization ; Scattering, Small Angle ; Ubiquitin Thiolesterase ; chemistry ; genetics ; metabolism ; Ultracentrifugation

To synthesize a series of 3-, 4-, and/or 11-trihydroxy modified bergenin derivatives and evaluated their cytotoxic activity in vitro. The phenolic hydroxyl groups of bergenin were protected by benzyl groups with benzyl bromide. Treatment of dibenzyl bergenin with the corresponding acid in the presence of EDC·HCl and DMAP in CH2Cl2, followed by hydrogenation over Pd/C catalysts, afforded derivatives of bergenin esters. All of the target compounds were identified by IR, MS, and (1)H NMR. Twenty-six novel and three known derivatives of bergenin esters were synthesized. Their cytotoxicity values were evaluated by the MTT assay on the inhibition of DU-145 and BGC-823 cells in vitro. Several triply-substituted (3a, 4a, 5a, 6a, 7a) and doubly-substituted (8b, 9b) bergenin derivatives exhibited higher cytotoxic activity than bergenin. The result showed that the size of substituents and the lipophilicity of the bergenin esters displayed an important role on their cytotoxic activity.
Antineoplastic Agents, Phytogenic ; chemical synthesis ; pharmacology ; therapeutic use ; Benzopyrans ; pharmacology ; therapeutic use ; Cell Line, Tumor ; Dipterocarpaceae ; chemistry ; Humans ; Male ; Molecular Structure ; Phytotherapy ; Plant Extracts ; pharmacology ; therapeutic use ; Prostatic Neoplasms ; drug therapy ; Stomach Neoplasms ; drug therapy ; Structure-Activity Relationship