UA62784 Is a Cytotoxic Inhibitor of Microtubules, not CENP-E

SummaryA recent screen for compounds that selectively targeted pancreatic cancer cells isolated UA62784. We found that UA62784 inhibits microtubule polymerization in vitro. UA62784 interacts with tubulin dimers ten times more potently than colchicine, vinblastine, or nocodazole. Competition experiments revealed that UA62784 interacts with tubulin at or near the colchicine-binding site. Nanomolar doses of UA62784 promote the accumulation of mammalian cells in mitosis, due to aberrant mitotic spindles, as shown by immunofluorescence and live cell imaging. Treatment of cancerous cell lines with UA62784 is lethal, following activation of apoptosis signaling. By monitoring mitotic spindle perturbations and apoptosis, we found that the effects of UA62784 and of some known microtubule-depolymerizing drugs are additive. Finally, high content screening of H2B-GFP HeLa cells revealed that low doses of UA62784 and vinblastine potentiate each other to inhibit proliferation

Synthesis and anticancer activity of novel 3,6-disubstituted 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole derivatives

AbstractThe development of new antitumor agents is one of the most pressing research areas in medicinal chemistry and medicine. The importance of triazole and thiadiazole rings as scaffolds present in a wide range of therapeutic agents has been well reported and has driven the synthesis of a large number of novel antitumor agents. The presence of these heterocycles furnishes extensive synthetic possibilities due to the presence of several reaction sites. Prompted by these data we designed, synthesized and evaluated a series of novel 3,6-disubstituted 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole derivatives as potential anticancer agents. We emphasized in the strategy of combining two chemically different but pharmacologically compatible molecules (the 1,2,4-triazole and 1,3,4 thiadiazole) in one frame. Several of the newly synthesized 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole derivatives showed substantial cytostatic and cytotoxic antineoplastic activity invitro, while they have produced relatively low acute toxicities invivo, giving potentially high therapeutic ratios. Insilico screening has revealed several protein targets including apoptotic protease-activating factor 1 (APAF1) and tyrosine-protein kinase HCK which may be involved in the biological activities of active analogues

Synthesis of alkaloids as glycosidase inhibitors from natural chiral sources

The main purpose of this work was the synthesis of polyhydroxylated pyrrolizidines and aza-C-disaccharide derivatives. These compounds, as azasugars show a great synthetic interest due to their biological activity, associated to their glycosidase and glycosyltransferase inhibition properties. The first goal of this work was to synthesize polyhydroxylated pyrrolizidines via 1,3-dipolar cycloadditions of chiral azomethine ylides. Azomethine ylides are generated in situ from the condensation reaction of chiral pyrrolidines with ethyl glyoxalate, through unstable iminium species. Two chiral pyrrolidines were used for this purpose, which have been synthesized from L-diethyl tartrate. In the cycloaddition reaction dimethyl fumarate, dimethyl maleate and N-phenyl maleimide were used as dipolarophiles. Interestingly the cycloadditions with dimethyl fumarate and dimethyl maleate gave the same cycloadduct. This result could be explained by the observed isomerisation of dimethyl maleate to dimethyl fumarate during the reaction. In all cases stucture elucidation of all cycloadducts was based on spectroscopic study, in particular 1H-NMR, and in one case on X-ray crystal structure analysis. Generally, the generated ylides react as anti-dipoles and give the desired pyrrolizidine derivatives through exo transition states with high diastereoselectivity. The second part of this work deals with the synthesis of aza-C-disaccharide derivatives, carrying a pyrrolidine unit. Our approach is based on the cycloaddition reaction of a chiral open chain nitrone and alkenes obtained from sugar precursors. Starting from D-ribose, we achieved nitrone synthesis with determined stereochemistry in all chiral centers. As dipolarophiles we chose alkenes that were easily prepared from D-glucose and D-galactose in good yields. Cycloaddition reactions of cis-alkenes proceeded in a diastereoselective manner and gave isoxazolidines suitable for building pyrrolidine rings. By this approach, two aza-C-disaccharide derivatives have been synthesized in high yields. Structure elucidation was based on spectroscopic data 1H-NMR, 13C-NMR and also on NOE, double resonance, COSY and ROESY experiments. Comparing to cis-alkenes obtained D-glucose and D-galactose, the cycloaddition reaction of a trans-alkene prepared from D-glucose, does not give the desired diastereoselectivity, and a mixture of four diastereomeric cycloadducts was obtained. It was possible to isolate and study only one of those cycloadducts, which was transformed to a new aza-C-disaccharide derivative. The third part of this work presents efforts to synthesize Hyacinthacine A3 and its epimers using as key reaction the Cope cyclisation of alkenyl-hydroxylamines. Unfortunately double nucleophilic substitution of dimesylate-derivatives by hydroxylamine did not give the desired alkenyl-hydroxylamines. The dimesylates were prepared from D-ribose and D-arabinose lactones using Grignard reagent addition reaction. In a variation of this procedure alkenyl-hydroxylamines were obtained from oxime’s reduction, without any significant diastereoselectivity. Aza-Cope cyclization of hydroxylamines gave the corresponding N-oxides, in a very complex reaction. At this point N-oxide isomers could not be isolated and our method was so aborted. The forth section presents efforts to synthesize aza-C-disaccharide derivatives, with a six- or a seven-member azasugar unit, using intermolecular 1,3-dipolar cycloaddition reaction of an appropriate-nitrone having an alkenyl substitute. The key step for nitrone synthesis was a vinyl-epoxide ring opening reaction by a sugar derived oxime. Unfortunately the intermolecular 1,3-dipolar cycloaddition reaction did not proceed and the alkenyl-nitrone did not give the desired isoxazolidines, in different reaction conditions, possibly for steric reasons

Aza-Reversine Promotes Reprogramming of Lung (MRC-5) and Differentiation of Mesenchymal Cells into Osteoblasts

Reversine or 2-(4-morpholinoanilino)-N6-cyclohexyladenine was originally identified as a small organic molecule that induces dedifferentiation of lineage-committed mouse myoblasts, C2C12, and redirects them into lipocytes or osteoblasts under lineage-specific conditions (LISCs). Further, it was proven that this small molecule can induce cell cycle arrest and apoptosis and thus selectively lead cancer cells to cell death. Further studies demonstrated that reversine, and more specifically the C2 position of the purine ring, can tolerate a wide range of substitutions without activity loss. In this study, a piperazine analog of reversine, also known as aza-reversine, and a biotinylated derivative of aza-reversine were synthesized, and their potential medical applications were investigated by transforming the endoderm originates fetal lung cells (MRC-5) into the mesoderm originated osteoblasts and by differentiating mesenchymal cells into osteoblasts. Moreover, the reprogramming capacity of aza-reversine and biotinylated aza-reversine was investigated against MRC-5 cells and mesenchymal cells after the immobilization on PMMA/HEMA polymeric surfaces. The results showed that both aza-reversine and the biofunctionalized, biotinylated analog induced the reprogramming of MRC-5 cells to a more primitive, pluripotent state and can further transform them into osteoblasts under osteogenic culture conditions. These molecules also induced the differentiation of dental and adipose mesenchymal cells to osteoblasts. Thus, the possibility to load a small molecule with useful “information” for delivering that into specific cell targets opens new therapeutic personalized applications

Regioselective Ene-Type Allylic Chlorination of Electron-Rich Alkenes by Activated DMSO

A simple protocol involving the activation of DMSO by chlorotrimethysilane is described for the chemoselective chlorination of polyprenoids. The proposed protocol provides a versatile and scalable alternative to existing routes for accessing useful synthetic synthons for the synthesis of complex terpenoids

Synthesis and Anti-Angiogenic Activity of Novel c(RGDyK) Peptide-Based JH-VII-139-1 Conjugates

Peptide–drug conjugates are delivery systems for selective delivery of cytotoxic agents to target cancer cells. In this work, the optimized synthesis of JH-VII-139-1 and its c(RGDyK) peptide conjugates is presented. The low nanomolar SRPK1 inhibitor, JH-VII-139-1, which is an analogue of Alectinib, was linked to the ανβ3 targeting oligopeptide c(RGDyK) through amide, carbamate and urea linkers. The chemostability, cytotoxic and antiangiogenic properties of the synthesized hybrids were thoroughly studied. All conjugates retained mid nanomolar-level inhibitory activity against SRPK1 kinase and two out of four conjugates, geo75 and geo77 exhibited antiproliferative effects with low micromolar IC50 values against HeLa, K562, MDA-MB231 and MCF7 cancer cells. The activities were strongly related to the stability of the linkers and the release of JH-VII-139-1. In vivo zebrafish screening assays demonstrated the ability of the synthesized conjugates to inhibit the length or width of intersegmental vessels (ISVs). Flow cytometry experiments were used to test the cellular uptake of a fluorescein tagged hybrid in MCF7 and MDA-MB231 cells that revealed a receptor-mediated endocytosis process. In conclusion, most conjugates retained the inhibitory potency against SRPK1 as JH-VII-139-1 and demonstrated antiproliferative and antiangiogenic activities. Further animal model experiments are needed to uncover the full potential of such peptide conjugates in cancer therapy and angiogenesis-related diseases

Anticancer Activity of Triazolo-Thiadiazole Derivatives and Inhibition of AKT1 and AKT2 Activation

The fusion of 1,2,4-triazole and 1,3,4-thiadiazole rings results in a class of heterocycles compounds with an extensive range of pharmacological properties. A series of 1,2,4-triazolo[3,4-b]-1,2,4-thiadiazoles was synthesized and tested for its enzyme inhibition potential and anticancer activity. The results show that 1,2,4-triazolo[3,4-b]-1,2,4-thiadiazoles display potent anticancer properties in vitro against a panel of cancer cells and in vivo efficacy in HT-29 human colon tumor xenograft in CB17 severe combined immunodeficient (SCID) mice. Preliminary mechanistic studies revealed that KA25 and KA39 exhibit time- and concentration-dependent inhibition of Akt Ser-473 phosphorylation. Molecular modeling experiments indicated that 1,2,4-triazolo[3,4-b]-1,2,4-thiadiazoles bind well to the ATP binding site in Akt1 and Akt2. The low acute toxicity combined with in vitro and in vivo anticancer activity render triazolo[3,4-b]thiadiazoles KA25, KA26, and KA39 promising cancer therapeutic agents

Discovery of steroidal lactam conjugates of POPAM-NH2 with potent anticancer activity

Aim: Steroidal prodrugs of nitrogen mustards such as estramustine and prednimustine have proven effective anticancer agents in clinical use since the 1970s. In this work, we aimed to develop steroidal prodrugs of the novel nitrogen mustard POPAM-NH2. POPAM-NH2 is a melphalan analogue that was coupled with three different steroidal lactams. Methodology: The new conjugates were preclinically tested for anticancer activity against nine human and one rodent cancer experimental models, in vitro and in vivo. Results & conclusion: All the steroidal alkylators showed high antitumor activity, in vitro and in vivo, in the experimental systems tested. Moreover, these hybrid compounds showed by far superior anticancer activity compared with the alkylating agents, melphalan and POPAM-NH2. [GRAPHICS]

Azasteroid Alkylators as Dual Inhibitors of AKT and ERK Signaling for the Treatment of Ovarian Carcinoma

(1) Background: Previous findings show that lactam steroidal alkylating esters display improved therapeutic efficacy with reduced toxicity. The aim of this study was to evaluate the anticancer activity of two newly synthesized aza-steroid alkylators (ENGA-L06E and ENGA-L08E) against human ovarian carcinoma cells, and consequently, the dual inhibition of RAS/PI3K/AKT and RAS/RAF/MEK/ERK signaling pathways, both of which are closely associated with ovarian cancer; (2) Methods: The in vitro cytostatic and cytotoxic effects of ENGA-L06E and ENGA-L08E were evaluated in a panel of five human ovarian cancer cell lines, as well as in in vivo studies. ENGA-L06E and ENGA-L08E, in addition to another two aniline-mustard alkylators, POPAM and melphalan (L-PAM), were utilized in order to determine the acute toxicity and antitumor efficacy on two human ovarian xenograft models. Also, in silico studies were performed in order to investigate the dual inhibition of ENGA-L06E and ENGA-L08E on RAS/PI3K/AKT and RAS/RAF/MEK/ERK signaling pathways; (3) Results: Both, in vitro and in vivo studies demonstrated that ENGA-L06E and ENGA-L08E were significantly more effective with a lower toxicity profile in comparison to POPAM and L-PAM alkylators. Moreover, in silico studies demonstrated that the two new aza-steroid alkylators could act as efficient inhibitors of the phosphorylation of AKT and ERK1/2 molecules; and (4) Conclusions: Both ENGA-L06E and ENGA-L08E demonstrated high anticancer activity through the inhibition of the PI3K-AKT and KRAS-ERK signaling pathways against human ovarian carcinoma, and thus constituting strong evidence towards further clinical development