Indolylarylsulfones as HIV-1 non-nucleoside reverse transcriptase inhibitors: new cyclic substituents at indole-2-carboxamide

New indolylarylsulfone derivatives bearing cyclic substituents at indole-2-carboxamide linked through a methylene/ethylene spacer were potent inhibitors of the WT HIV-1 replication in CEM and PBMC cells with inhibitory concentrations in the low nanomolar range. Against the mutant L100I and K103N RT HIV-1 strains in MT-4 cells, compounds 20, 24-26, 36, and 40 showed antiviral potency superior to that of NVP and EFV. Against these mutant strains, derivatives 20, 24-26, and 40 were equipotent to ETV. Molecular docking experiments on this novel series of IAS analogues have also suggested that the H-bond interaction between the nitrogen atom in the carboxamide chain of IAS and Glu138:B is important in the binding of these compounds. These results are in accordance with the experimental data obtained on the WT and on the mutant HIV-1 strains tested.     

Liposome-encapsulated doxorubicin reverses drug resistance by inhibiting P-glycoprotein in human cancer cells

The most frequent drawback of doxorubicin is the onset of drug resistance, due to the active efflux through P-glycoprotein (Pgp). Recently formulations of liposome-encapsulated doxorubicin have been approved for the treatment of tumors resistant to conventional anticancer drugs, but the molecular basis of their efficacy is not known. To clarify by which mechanisms the liposome-encapsulated doxorubicin is effective in drug-resistant cancer cells, we analyzed the effects of doxorubicin and doxorubicin-containing anionic liposomal nanoparticles ("Lipodox") on the drug-sensitive human colon cancer HT29 cells and on the drug-resistant HT29-dx cells. Interestingly, we did not detect any difference in drug accumulation and toxicity between free doxorubicin and Lipodox in HT29 cells, but Lipodox was significantly more effective than doxorubicin in HT29-dx cells, which are rich in Pgp. This effect was lost in HT29-dx cells silenced for Pgp and acquired by HT29 cells overexpressing Pgp. Lipodox was less extruded by Pgp than doxorubicin and inhibited the pump activity. This inhibition was due to a double effect: the liposome shell per se altered the composition of rafts in resistant cells and decreased the lipid raft-associated amount of Pgp, and the doxorubicin-loaded liposomes directly impaired transport and ATPase activity of Pgp. The efficacy of Lipodox was not increased by verapamil and cyclosporin A and was underwent interference by colchicine. Binding assays revealed that Lipodox competed with verapamil for binding Pgp and hampered the interaction of colchicine with this transporter. Site-directed mutagenesis experiments demonstrated that glycine 185 is a critical residue for the direct inhibitory effect of Lipodox on Pgp. Our work describes novel properties of liposomal doxorubicin, investigating the molecular bases that make this formulation an inhibitor of Pgp activity and a vehicle particularly indicated against drug-resistant tumors.     

Glucagon‐like peptide‐1 receptor activation stimulates hepatic lipid oxidation and restores hepatic signalling alteration induced by a high‐fat diet in nonalcoholic steatohepatitis

Background/Aims: High‐fat dietary intake and low physical activity lead to insulin resistance, nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Recent studies have shown an effect of glucagon‐like peptide‐1 (GLP‐1) on hepatic glucose metabolism, although GLP‐1 receptors (GLP‐1r) have not been found in human livers. The aim of this study was to investigate the presence of hepatic GLP‐1r and the effect of exenatide, a GLP‐1 analogue, on hepatic signalling. Methods: The expression of GLP‐1r was evaluated in human liver biopsies and in the livers of high‐fat diet‐treated rats. The effect of exenatide (100 nM) was evaluated in hepatic cells of rats fed 3 months with the high‐fat diet. Results: GLP‐1r is expressed in human hepatocytes, although reduced in patients with NASH. Similarly, in rats with NASH resulted from 3 months of the high‐fat diet, we found a decreased expression of GLP‐1r and peroxisome proliferator‐activated receptor γ (PPARγ), and reduced peroxisome proliferator‐activated receptor α (PPARα) activity. Incubation of hepatocytes with exenatide increased PPARγ expression, which also exerted an insulin‐sensitizing action by reducing JNK phosphorylation. Moreover, exenatide increased protein kinase A (PKA) activity, Akt and AMPK phosphorylation and determined a PKA‐dependent increase of PPARα activity. Conclusions: GLP‐1 has a direct effect on hepatocytes, by activating genes involved in fatty acid β‐oxidation and insulin sensitivity. GLP‐1 analogues could be a promising treatment approach to improve hepatic insulin resistance in patients with NAFLD/NASH.     

The MET Oncogene Is a Functional Marker of a Glioblastoma Stem Cell Subtype

The existence of treatment-resistant cancer stem cells contributes to the aggressive phenotype of glioblastoma. However, the molecular alterations that drive stem cell proliferation in these tumors remain unknown. In this study, we found that expression of the MET oncogene was associated with neurospheres expressing the gene signature of mesenchymal and proneural subtypes of glioblastoma. Met expression was almost absent from neurospheres expressing the signature of the classical subtype and was mutually exclusive with amplification and expression of the EGF receptor (EGFR) gene. Met-positive and Met-negative neurospheres displayed distinct growth factor requirements, differentiated along divergent pathways, and generated tumors with distinctive features. The Met(high) subpopulation within Met-pos neurospheres displayed clonogenic potential and long-term self-renewal ability in vitro and enhanced growth kinetics in vivo. In Met(high) cells, the Met ligand HGF further sustained proliferation, clonogenicity, expression of self-renewal markers, migration, and invasion in vitro. Together, our findings suggest that Met is a functional marker of glioblastoma stem cells and a candidate target for identification and therapy of a subset of glioblastomas. Cancer Res; 72(17); 4537-50. ?2012 AACR.     

Ex vivo response to mucosal bacteria and muramyl dipeptide in inflammatory bowel disease

AIM To evaluate how mucosal bacteria impact on the spontaneous and muramyl dipeptide(MDP)-induced inflammation in Crohn's disease(CD) and ulcerative colitis(UC).METHODS Colonic mucosal biopsies were collected from children with active or remissive CD, UC and controls. Two tissue samples were taken from inflamed mucosal segments(in patients with active disease) or from noninflamed mucosa [in patients in remission or in healthy controls(HC)]. Experiments were performed in the presence or absence of antibiotics, to assess whether the disease-associated microbiota can modulate the cytokine response ex vivo. For this purpose, each specimen was half-cut to compare spontaneous and MDP-induced inflammation in the presence of live bacteria(LB) or antibiotics. After 24 h of culture, an array of 17 cytokines was assessed in supernatants. Statistical analyses were performed to find significant differences in single cytokines or in patterns of cytokine response in the different groups. RESULTS We demonstrated that subjects with CD display a spontaneous production of inflammatory cytokines including granulocyte-colony stimulating factor(G-CSF), interleukin(IL) 6, IL8, IL10 and IL12, that was not significantly influenced by the addition of antibiotics. UC specimens also displayed a trend of increased spontaneous secretion of several cytokines, which however was not significant due to broader variability among patients. After the addition of antibiotics, spontaneous IL8 secretion was significantly higher in UC than in controls. In HC, a trend towards the weakening of spontaneous IL8 production was observed in the presence of live mucosal bacteria with respect to the presence of antibiotics. In contrast, in the presence of LB UC showed an increasing trend of spontaneous IL8 production, while MDP stimulation resulted in lower IL8 production in the presence of antibiotics. We also showed that subjects with CD seem to have a lowered production of IL8 in response to MDP in the presence of LB. Only with the addition of antibiotics, likely reducing the contribution of LB, multivariate statistical analysis could identify the combination of measures of G-CSF, tumor necrosis factor alpha, IL4 and IL17 as a good discriminator between CD and UC.CONCLUSION We showed that the presence of LB or antibiotics can significantly influence the inflammatory response ex vivo in inflammatory bowel diseases.