Discovery of novel 2-aryl-3-sulfonamido-pyridines (HoAns) as microtubule polymerization inhibitors with potent antitumor activities

A novel amino-pyrimidine inhibitor suppresses tumor growth via microtubule destabilization and Bmi-1 down-regulation

Colorectal cancer (CRC), one of the diseases posing a threat to global health, according to the latest data, is the third most common cancer globally and the second leading cause of cancer-related deaths. The development and refinement of novel structures of small molecular compounds play a crucial role in tumor treatment and overcoming drug resistance. In this study, our objective was to screen and characterize novel compounds for overcoming drug resistance via the B Lymphoma Mo-MLV insertion region 1 (Bmi-1) reporter screen assay. The stable cell line harboring the Bmi-1 reporter gene was utilized to screen 300 compounds, leading to the identification of an amino-pyrimidine compound, APD-94. In vitro, APD-94 markedly inhibited cancer cell proliferation and decreased Bmi-1 expression at both the RNA and protein levels. In vivo, APD-94 repressed the growth of HT29 cell xenografts in NOD/SCID mice without notable side effects. Flow cytometry results demonstrated that APD-94 induced G2/M phase arrest and apoptosis in cells. APD-94 was identified as a novel inhibitor of microtubule polymerization by directly targeting the tubulin. Furthermore, APD-94 was more effective in overcoming the resistance to paclitaxel in paclitaxel-resistant A549/Tax cells. This bifunctional inhibitor is a promising candidate drug for CRC treatment.

Design, synthesis, and antitumor evaluation of quinazoline-4-tetrahydroquinoline chemotypes as novel tubulin polymerization inhibitors targeting the colchicine site

We designed, synthesized, and evaluated the antitumor activity of a series of novel quinazoline-4-(6-methoxytetrahydroquinoline) analogues. Among the tested compounds, 4a4 exhibited the most potent antiproliferative activities across four human cancer cell lines with half-maximal inhibitory concentration (IC50) values ranging from 0.4 to 2.7 nM, more potent than the lead compound. The 2.71 Å resolution co-crystal structure of 4a4 with tubulin (PDB code: 8YER) confirmed its critical binding at the colchicine site. Moreover, 4a4 inhibited the polymerization of tubulin, colony formation, and tumor cell migration, while inducing G2/M phase arrest and apoptosis. In vivo, 4a4 significantly delayed primary tumor growth in the SKOV3 xenograft model without obvious side effect. Our research enhances the structure-activity relationships (SARs) understanding of the quinazoline-4-tetrahydroquinoline scaffold and provides new insights for potential structural optimization and the development of novel colchicine binding site inhibitors (CBSIs).

Dual-target inhibitors of colchicine binding site for cancer treatment

Colchicine binding site inhibitors (CBSIs) have attracted much attention due to their antitumor efficacies and the advantages of inhibiting angiogenesis and overcoming multidrug resistance. However, no CBSI has been currently approved for cancer treatment due to the insufficient efficacies, serious toxicities and poor pharmacokinetic properties. Design of dual-target inhibitors is becoming a potential strategy for cancer treatment to improve anticancer efficacy, decrease adverse events and overcome drug resistance. Therefore, we reviewed dual-target inhibitors of colchicine binding site (CBS), summarized the design strategies and the biological activities of these dual-target inhibitors, expecting to provide inspiration for developing novel dual inhibitors based on CBS.

Discovery of polymethoxyphenyl-pyridines bearing amino side chains as tubulin colchicine-binding site inhibitors

Nineteen TH03 analogues were designed and synthesized as tubulin colchicine-binding site inhibitors with potent antiproliferative activities. Among these compounds, 3,5-dimethoxyphenylpyridines 8j bearing a 4-methoxybenzyl aniline side-chain displayed the best antiproliferative activities against glioma (U87MG and U251). In addition, the trimethoxyphenylpyridine 8o bearing a 4-methyl-N-methyl aniline side-chain showed the best antiproliferative activities against colon carcinoma and lung cancer with the lowest IC₅₀ value (0.09 µM < IC₅₀ < 0.86 µM). Compared with CA-4, Compounds 8j and 8o displayed lower cytotoxicities toward normal cells but higher antiproliferative activities against RKO (IC₅₀ = 0.15 µM and 0.09 µM respectively), NCI-H1299 (IC₅₀ = 0.73 µM and 0.14 µM respectively), and A549 cells (IC₅₀ = 0.86 µM and 0.37 µM respectively). Further investigations revealed that 8o shows higher tubulin polymerization inhibitory activity (IC₅₀ = 3.1 ± 0.5 µM) than colchicine (IC₅₀ = 8.6 ± 0.2 µM), and induced cell cycle arrest at the G2/M phase and cellular apoptosis through disrupting the microtubule network.

Novel substituted 5-methyl-4-acylaminoisoxazoles as antimitotic agents: Evaluation of selectivity to LNCaP cancer cells

A series of novel antimitotic agents was designed using the replacement of heterocyclic cores in two tubulin-targeting lead molecules with the acylated 4-aminoisoxazole moiety. Target compounds were synthesized via heterocyclization of β-aryl-substituted vinylketones by tert-butyl nitrite in the presence of water as a key step. 4-Methyl-N-[5-methyl-3-(3,4,5-trimethoxyphenyl)isoxazol-4-yl]benzamide (1aa) was found to stimulate partial depolymerization of microtubules of human lung carcinoma A549 cells at a high concentration of 100 µM and to totally inhibit cell growth (IC₅₀  = 0.99 µM) and cell viability (IC₅₀  = 0.271 µM) in the nanomolar to submicromolar concentration range. These data provide evidence of the multitarget profile of the cytotoxic action of compound 1aa. The SAR study demonstrated that the 3,4,5-trimethoxyphenyl residue is the key structural parameter determining the efficiency both towards tubulin and other molecular targets. The cytotoxicity of 3-methyl-N-[5-methyl-3-(3,4,5-trimethoxyphenyl)isoxazol-4-yl]benzamide (1ab) to the androgen-sensitive human prostate adenocarcinoma cancer cell line LNCaP (IC₅₀  = 0.301 µM) was approximately one order of magnitude higher than that to the conditionally normal cells lines WI-26 VA4 (IC₅₀  = 2.26 µM) and human umbilical vein endothelial cells (IC₅₀  = 5.58 µM) and significantly higher than that to primary fibroblasts (IC₅₀  > 75 µM).

Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

Recently, the development of nanocatalysts based on naturally occurring polysaccharides has received a lot of attention. Chitosan (CS), as a biodegradable and biocompatible polysaccharide, is considered to be an excellent template for the design of a hybrid biopolymer-based metal oxide nanocomposite. In this case, lanthanum oxide nanoparticles doped with chitosan at different weight percentages (5, 10, 15, and 20 wt% CS/La2O3) were prepared via a simple solution casting method. The prepared CS/La2O3 nanocomposite solutions were cast in a Petri dish in order to produce the developed catalyst, which was shaped as a thin film. The structural features of the hybrid nanocomposite film were studied by FTIR, SEM, and XRD analytical tools. FTIR spectra confirmed the presence of the major characteristic peaks of chitosan, which were modified by interaction with La2O3 nanoparticles. Additionally, SEM graphs showed dramatic morphological changes on the surface of chitosan, which is attributed to surface adsorption with La2O3 molecules. The prepared CS/La2O3 nanocomposite film (15% by weight) was investigated as an effective, recyclable, and heterogeneous base catalyst in the synthesis of pyridines and pyrazoles. The nanocomposite used was sufficiently stable and was collected and reused more than three times without loss of catalytic activity.