ABSTRACT
To address the scarcity of direct comparison of botulinum neurotoxin serotypes activity on smooth versus striatal muscle, we have studied the action of BoNT/A1 and BoNT/B1 on ex vivo preparations of both muscle types. We have set up and characterized a model of neurogenic contractions in the isolated mouse bladder, and used this model to explore the effects of the two serotypes on contractions evoked by electrical field stimulation. Both toxins were also tested in the mouse phrenic nerve hemidiaphragm assay, to compare their potency in smooth versus striated muscle. The characterization of the model of neurogenic contractions in the isolated mouse bladder indicates that about half of the activity is driven by purinergic signaling, and about half by cholinergic signaling. Furthermore, we find that BoNT/B1 is more potent than BoNT/A1 in inhibiting activity in the mouse detrusor smooth muscle preparation, but that both toxins have comparable potency on the striated muscle activity of the phrenic nerve hemidiaphragm model. We also show that these findings are mouse strain independent. In conclusion, the established mouse bladder detrusor smooth muscle model is able to discriminate between different botulinum neurotoxin serotypes and could be a useful preclinical tool to explore the pathophysiology of bladder overactivity, as well as the effects of new therapeutic candidates. It is interesting to note that the high proportion of purinergic transmission driving detrusor contractions in this model is similar to that seen in neurodetrusor overactivity disease, making this model relevant with regard to pathophysiological interest.
ABSTRACT
The 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) catalyze the interconversion between the oxidized and reduced forms of androgens and estrogens at the 17 position. The 17beta-HSD type 1 enzyme (17beta-HSD1) catalyzes the reduction of estrone (E1) to estradiol and is expressed in malignant breast cells. Inhibitors of this enzyme thus have potential as treatments for hormone dependent breast cancer. Syntheses and biological evaluation of novel non-steroidal inhibitors designed to mimic the E1 template are reported using information from potent steroidal inhibitors. Of the templates investigated biphenyl ethanone was promising and led to inhibitors with IC(50) values in the low micromolar range.
Subject(s)
17-Hydroxysteroid Dehydrogenases/antagonists & inhibitors , Drug Design , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , 17-Hydroxysteroid Dehydrogenases/metabolism , Cell Line, Tumor , Enzyme Inhibitors/chemistry , Humans , Molecular Structure , Structure-Activity RelationshipABSTRACT
A series of 4-arylimidazole carbamates was synthesized and their binding affinities to the site-2 sodium (Na+) channel were determined. SAR studies led to the identification of compound 10, a potent Na+ channel blocker which was efficacious in pain models in vivo.
Subject(s)
Carbamates/chemical synthesis , Carbamates/pharmacology , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Pain/drug therapy , Pain/etiology , Peripheral Nervous System Diseases/complications , Sodium Channel Blockers/chemical synthesis , Sodium Channel Blockers/pharmacology , Animals , Batrachotoxins , Binding, Competitive/drug effects , Carrageenan , Humans , Hyperalgesia/chemically induced , Hyperalgesia/drug therapy , Indicators and Reagents , Microsomes/drug effects , Microsomes/metabolism , Rats , Sodium/metabolism , Structure-Activity Relationship , Synaptosomes/drug effects , Synaptosomes/metabolism , Veratridine/pharmacologyABSTRACT
A large number of hormones and local agonists activating guanine-binding protein-coupled receptors (GPCR) play a major role in cancer progression. Here, we characterize the new imidazo-pyrazine derivative BIM-46174, which acts as a selective inhibitor of heterotrimeric G-protein complex. BIM-46174 prevents the heterotrimeric G-protein signaling linked to several GPCRs mediating (a) cyclic AMP generation (Galphas), (b) calcium release (Galphaq), and (c) cancer cell invasion by Wnt-2 frizzled receptors and high-affinity neurotensin receptors (Galphao/i and Galphaq). BIM-46174 inhibits the growth of a large panel of human cancer cell lines, including anticancer drug-resistant cells. Exposure of cancer cells to BIM-46174 leads to caspase-3-dependent apoptosis and poly(ADP-ribose) polymerase cleavage. National Cancer Institute COMPARE analysis for BIM-46174 supports its novel pharmacologic profile compared with 12,000 anticancer agents. The growth rate of human tumor xenografts in athymic mice is significantly reduced after administration of BIM-46174 combined with either cisplatin, farnesyltransferase inhibitor, or topoisomerase inhibitors. Our data validate the feasibility of targeting heterotrimeric G-protein functions downstream the GPCRs to improve anticancer chemotherapy.
Subject(s)
Cysteine/analogs & derivatives , Heterotrimeric GTP-Binding Proteins/antagonists & inhibitors , Imidazoles/pharmacology , Animals , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Cycle/drug effects , Cell Growth Processes/drug effects , Cell Line, Tumor , Cysteine/pharmacology , Drug Screening Assays, Antitumor , Female , GTP-Binding Protein alpha Subunits/antagonists & inhibitors , GTP-Binding Protein alpha Subunits/metabolism , GTP-Binding Protein beta Subunits/antagonists & inhibitors , GTP-Binding Protein beta Subunits/metabolism , GTP-Binding Protein gamma Subunits/antagonists & inhibitors , GTP-Binding Protein gamma Subunits/metabolism , HL-60 Cells , Heterotrimeric GTP-Binding Proteins/metabolism , Humans , Mice , Neoplasm Invasiveness , Xenograft Model Antitumor AssaysABSTRACT
BN80927 belongs to a novel family of camptothecin analogs, the homocamptothecins, developed on the concept of topoisomerase I (Topo I) inhibition and characterized by a stable seven-membered beta-hydroxylactone ring. Preclinical data reported here show that BN80927 retains Topo I poisoning activity in cell-free assay (DNA relaxation) as well as in living cells, in which in vivo complexes of topoisomerase experiments and quantification of DNA-protein-complexes stabilization, have confirmed the higher potency of BN80927 as compared with the Topo I inhibitor SN38. In addition, BN80927 inhibits Topo II-mediated DNA relaxation in vitro but without cleavable-complex stabilization, thus indicating catalytic inhibition. Moreover, a Topo I-altered cell line (KBSTP2), resistant to SN38, remains sensitive to BN80927, suggesting that a part of the antiproliferative effects of BN80927 are mediated by a Topo I-independent pathway. This hypothesis is also supported by in vitro data showing an antiproliferative activity of BN80927 on a model of resistance related to the noncycling state of cells (G(0)-G(1) synchronized). In cell growth assays, BN80927 is a very potent antiproliferative agent as shown by IC(50) values consistently lower than those of SN38 in tumor cell lines as well as in their related drug-resistant lines. BN80927 shows high efficiency in vivo in tumor xenograft studies using human androgen-independent prostate tumors PC3 and DU145. Altogether, these data strongly support the clinical development of BN80927.
Subject(s)
Antineoplastic Agents/pharmacology , Camptothecin/analogs & derivatives , Camptothecin/pharmacology , Prostatic Neoplasms/drug therapy , Adenocarcinoma/blood , Adenocarcinoma/drug therapy , Adenocarcinoma/enzymology , Adenocarcinoma/pathology , Animals , Camptothecin/blood , Cell Division/drug effects , Cell Line, Tumor , DNA Topoisomerases, Type I/metabolism , DNA Topoisomerases, Type II/metabolism , DNA, Superhelical/drug effects , DNA, Superhelical/metabolism , Drug Screening Assays, Antitumor , Drug Stability , Enzyme Inhibitors/pharmacology , HL-60 Cells , Humans , K562 Cells , Male , Mice , Mice, Nude , Neoplasms, Hormone-Dependent/drug therapy , Neoplasms, Hormone-Dependent/pathology , Prostatic Neoplasms/blood , Prostatic Neoplasms/enzymology , Prostatic Neoplasms/pathology , Topoisomerase I Inhibitors , Topoisomerase II Inhibitors , Xenograft Model Antitumor AssaysABSTRACT
A series of 2-alkyl-4-arylimidazoles were prepared and their binding affinities to the site-2 sodium (Na+) channel were determined. SAR studies led to highly potent Na+ channel blockers.
