Target Tubulin Research Articles

Synthesis, biological evaluation and mechanism study of a novel indole-pyridine chalcone derivative as antiproliferative agent against tumor cells through dual targeting tubulin and HK2

Synthesis, biological evaluation and mechanism study of a novel indole-pyridine chalcone derivative as antiproliferative agent against tumor cells through dual targeting tubulin and HK2

The mode of action of sorafenib in MDA-MB-231 breast carcinoma cells involves components of apoptotic, necroptotic and autophagy-dependent cell death pathways

We report the identification of an interesting mode of action by sorafenib (SF) (Nexavar) in triple-negative breast adenocarcinoma MDA-MB-231 cells. The dying cells presented features of apoptosis, such as externalization of phosphatidylserine and cleaved caspase-3, and autophagy-mediated cell death, such as formation of autophagosomes and autolysosomes, the overexpression of LC3-II, and the presence of LAMP1-positive vacuoles, while displaying insufficient autophagic flux. Components of endoplasmic reticulum stress (ER stress; PERK and CHOP) and of necroptosis (p-MLKL) were also elevated considerably. Investigating potential target proteins that could modulate this form of cell death, we next investigated the role of tubulin disruption, which is known to induce necroptosis, apoptosis, and autophagy-dependent cell death. Interactions of SF with purified tubulin were investigated in detail using a combination of cellular and biophysical assays, transmission electron microscopy, and computer simulations. A marked reduction in the intrinsic tryptophan fluorescence of tubulin, a concentration-dependent elevation of anilinonaphthalene sulfonate–tubulin complex fluorescence, electron micrographs of deformed in vitro–assembled microtubules, and disrupted and hyper-stabilized cellular microtubules evinced the ability of SF to target tubulin and disrupt cellular microtubules. Molecular docking and molecular dynamic simulations positioned the drug between the α and β subunits of tubulin with considerable stability (ΔGbind, −31.43 kcal/mol), suggesting that drug-induced perturbation of tubulin could contribute to this mode of cell death.

Palmitic acid causes hepatocyte inflammation by suppressing the BMAL1-NAD+-SIRT2 axis.

Palmitic acid is the most abundant saturated fatty acid in circulation and causes hepatocyte toxicity and inflammation. As saturated fatty acid can also disrupt the circadian rhythm, the present work evaluated the connection between clock genes and NAD+ dependent Sirtuins in protecting hepatocytes from lipid-induced damage. Hepatocytes (immortal cells PH5CH8, hepatoma cells HepG2) treated with higher doses of palmitic acid (400-600μM) showed typical features of steatosis accompanied with growth inhibition and increased level of inflammatory markers (IL-6 IL-8, IL-1α and IL-1β) together with decline in NAD+ levels. Palmitic acid treated hepatocytes showed significant decline in not only the protein levels of SIRT2 but also its activity as revealed by the acetylation status of its downstream targets (Tubulin and NF-ƙB). Additionally, the circadian expression of both SIRT2 and BMAL1 was inhibited in presence of palmitic acid in only the non-cancerous hepatocytes, PH5CH8 cells. Clinical specimens obtained from subjects with NASH-associated fibrosis, ranging from absent (F0) to cirrhosis (F4), showed a significant decline in levels of SIRT2 and BMAL1, especially in the cirrhotic liver. Ectopic expression of BMAL1 or activating SIRT2 by supplementation with nicotinamide riboside (precursor of NAD+) dampened the palmitic acid induced lipoinflammation and lipotoxicity more effectively in PH5CH8 cells as compared to HepG2 cells. Mechanistically, palmitic acid caused transcriptional suppression of SIRT2 by disrupting the chromatin occupancy of BMAL1 at its promoter site. Overall, the work suggested that SIRT2 is a clock-controlled gene that is transcriptionally regulated by BMAL1. In conclusion the activation of the BMAL1-NAD+-SIRT2 axis shows hepatoprotective effects by preventing lipotoxicity and dampening inflammation.

Tetrahydrocarbazoles incorporating 5-arylidene-4-thiazolinones as potential antileukemia and antilymphoma targeting tyrosine kinase and tubulin polymerase enzymes: Design, synthesis, structural, biological and molecular docking studies

Finding effective and selective anticancer agents is a top medical priority due to high clinical treatment demand. However, current anticancer agents have serious side effects and resistance development remains a big concern. This creates an urgent need for new multitarget drugs that could solve these problems. Tetrahydrocarbazoles and 5-arylidene-4-thiazolinones have always attracted researchers for their multifaced anticancer activities and the possibility to be easily derivatized. Thereby, herein we report the combination of the two scaffolds to provide compounds 9a-j and 10a-j that were fully characterized and their tautomeric form was confirmed by crystal structure. 9a-j and 10a-j wereassessedfor invitro antiproliferative activityusing SRB assay against a panel of seven human cancer cell lines with doxorubicin as the standard. The results revealed that the cell lines derived from leukemia (Jurkat) and lymphoma (U937) are the most sensitive. Compounds 9d, 10e, 10g, and 10f revealed the highest potency (IC50 = 3.11–11.89 μM) with much lower effects on normal lymphocytes cell line (IC50 > 50 µM). The results show that modifications at 6th position of the THC and the nature of the substituent at the arylidene moiety affect the activity. To exploit the mode of action, 9d, 10e, 10f, and 10g were evaluated as VEGFR-2 and EGFR inhibitors. 10e is the most potent (IC50 0.26 and 0.14 μM) against both enzymes. It also induced G0-G1-phase cell cycle arrest and apoptosis. While 10g exhibited higher potency (IC50 9.95 μM) than vincristine (IC50 15.63 μM) against tubulin. A molecular docking study was carried out to understand the interactions between 10e, 10g and their targets. This study reveals 10e and 10g as possible candidates for developing multitarget anticancer agents against leukemia and lymphoma.

Scaffold overlay of flavonoid-inspired molecules: Discovery of 2,3-diaryl-pyridopyrimidin-4-imine/ones as dual hTopo-II and tubulin targeting anticancer agents

Almost half of all medicines approved by the U.S. Food and Drug Administration have been found to be developed based on inspiration from natural products (NPs). Here, we report a novel strategy of scaffold overlaying of scaffold-hopped analogs of bioactive flavones and isoflavones and installation of drug-privileged motifs, which has led to discovery of anticancer agents that surpass the functional efficiency of the original NPs. The analogs, 2,3-diaryl-pyridopyrimidin-4-imine/ones were efficiently synthesized by an approach of a nitrile-stabilized quaternary ammonium ylide as masked synthon and Pd-catalyzed activation–arylation methods. Compared to the NPs, these NP-analogs exhibited differentiated functions; dual inhibition of human topoisomerase-II (hTopo-II) enzyme and tubulin polymerization, and pronounced antiproliferative effect against various cancer cell lines, including numerous drug-resistant cancer cells. The most active compound 5l displayed significant inhibition of migration ability of cancer cells and blocked G1/S phase transition in cell cycle. Compound 5l caused pronounced effect in expression patterns of various key cell cycle regulatory proteins; up-regulation of apoptotic proteins, Bax, Caspase 3 and p53, and down-regulation of apoptosis-inhibiting proteins, BcL-xL, Cyclin D1, Cyclin E1 and NF-κB, which indicates high efficiency of the molecule 5l in apoptosis-signal axis interfering potential. Cheminformatics analysis revealed that 2,3-diaryl-pyridopyrimidin-4-imine/ones occupy a distinctive drug-relevant chemical space that is seldom represented by natural products and good physicochemical, ADMET and pharmacokinetic-relevant profile. Together, the anticancer potential of the investigated analogs was found to be much more efficient compared to the original natural products and two anticancer drugs, Etoposide (hTopo-II inhibitor) and 5-Flurouracile (5-FU).

New Benzylidene‐Triazole Tethered Coumarin Molecular Hybrids: Synthesis, SAR, Molecular Modelling Simulations Targeting Tubulin α/β Dimer and its Antimicrobial Evaluation

AbstractA series of new 7‐{3‐[3‐(Benzylidene‐amino)‐[1,2,4]triazole‐1‐yl]‐propoxy}‐4‐methyl‐chromen‐2‐one molecular hybrids 7(a–k) were synthesized using molecular hybridization approach. The synthesized new benzylidene‐triazole tethered coumarin molecular hybrids were characterized by spectroscopic studies and elemental analysis. The coumarin molecular hybrids have been explored for their antifungal efficacy in terms of tubulin inhibitors using molecular modelling studies against tubulin alphabeta hetero dimer protein. The results clearly demonstrated strong binding affinity of coumarin molecular hybrids with indole substituted and 2,4‐dihydroxy substituted as antagonists with respective binding scores of −10.5 and −10.7 kcal/mol towards tubulin alphabeta hetero dimer protein which was higher in comparison to standards griseofulvin (−8.2 kcal/mol) and fluconazole (−8.1 kcal/mol). In addition, broth dilution method was used to conduct in‐vitro antifungal studies against three fungal strains namely Candida albicans, Aspergillus niger and Aspergillus fumigatus. The results obtained clearly illustrate the antifungal activity of indole and 2,4‐dihydroxy substituted compounds which are consistent with docking simulations. Out of all the synthesized molecular hybrids, indole and 2,4‐dihydroxy substituted compounds depict outstanding antifungal activity with Minimum Inhibitory Concentration (MIC) value of 31.25 μg/ml and 62.5 μg/ml towards C.albicans and with MIC value of 31.25 for both these molecules towards A.niger in each case which is quite higher than griseofulvin and fluconazole respectively. Present work clearly demonstrates the potential efficacy of synthesized indole and 2,4‐dihydroxy substituted coumarin molecular hybrids to be considered as lead compounds for the development of new agents against resistant strains for the treatment of fungal infection.

Oxindoline Containing Thiazolidine‐4‐one Tethered Triazoles Act as Antimitotic Agents by Targeting Microtubule Dynamics

AbstractOxindoline containing thiazolidine‐4‐ones linked triazole hybrids (24 a–l) series were synthesized by multistep synthesis and tested for their cytotoxic activity against four human cancer cell lines. Significantly higher susceptibility was observed in liver (HepG2) cancer cells. Among them conjugates 24 c and 24 e exhibited promising cytotoxicity with IC50 values of 1.64 μM, and 2.07 μM respectively when compared to the standard 5‐fluorouracil (IC50=20.8 μM) against the HepG2 cell line. Later on, these compounds changed the morphology of HepG2 cells and significantly inhibited colony formation in HepG2 in a dose‐dependent manner. The scratch assay divulged that these compounds decreased wound size and inhibited cell migration. Interestingly, they induced the cell cycle arrest at the S phase. Moreover, the DCFDA assay indicated ROS production proportionate to compound dose and AO/Eb staining revealed increased apoptotic cell count with higher doses. The tubulin polymerization assay reveals that they inhibited the microtubules and acted as antimitotic agents. In‐silico results of these conjugates also support their tubulin inhibitory properties. Interestingly, these compounds have adequate ADME‐toxicity parameters. Based on free energy calculation results, it was observed that these inhibitors influence the conformational flexibility of the target tubulin protein.

Synthesis of Some New Coumarin-thiazolidine-2,4-dione-1,2,3-triazole Hybrids as Tubulin Targeting Anti-Lung Cancer Agents

Synthesis of Some New Coumarin-thiazolidine-2,4-dione-1,2,3-triazole Hybrids as Tubulin Targeting Anti-Lung Cancer Agents

Design and synthesis of novel 3-amino-5-phenylpyrazole derivatives as tubulin polymerization inhibitors targeting the colchicine-binding site

As the basic unit of microtubules, tubulin is one of the most important targets in the study of anticarcinogens. A novel series of 3-amino-5-phenylpyrazole derivatives were designed and synthesized, and evaluates for their biological activities. Among them, a majority of compounds exerted excellent inhibitory activities against five cancer cell lines in vitro. Especially, compound 5b showed a strong antiproliferative activity against MCF-7 cells, with IC50 value of 38.37 nM. Further research indicated that compound 5b can inhibit the polymerization of tubulin targeting the tubulin colchicine-binding sites. Furthermore, 5b could arrest MCF-7 cells at the G2/M phase and induce MCF-7 cells apoptotic in a dose-dependent and time-dependent manners, and regulate the level of related proteins expression. Besides, compound 5b could inhibit the cancer cell migration and angiogenesis. In addition, 5b could inhibit tumor growth in MCF-7 xenograft model without obvious toxicity. All these results indicating that 5b could be a promising antitumor agent targeting tubulin colchicine-binding site and it was worth further study.

Discovery of the cereblon-recruiting tubulin PROTACs effective in overcoming Taxol resistance in vitro and in vivo

Overexpression of β3-tubulin is a common occurrence in human tumors and is associated with resistance to microtubule-targeting agents. PROTAC strategy has demonstrated significant potential in overcoming drug resistance. Herein, we report the discovery of W13 as the first PROTAC against tubulin, which was created by connecting a CRBN ligand to the widely recognized microtubule-destabilizing agent CA-4. Notably, it retains the inhibitory activity of the parental CA-4 and further exhibits substantial degradation of α/β/β3-tubulin in both A549 and A549/Taxol cell lines. The degradation of tubulin was subsequently verified to be mediated by the ubiquitin-proteasome system. Importantly, tumor xenograft research clearly showed W13's promising antitumor activity against human lung cancer. Taken together, the discovery of W13 demonstrated the practicality and feasibility of PROTAC targeting tubulin, hence establishing a potential therapeutic approach for treating NSCLC caused by the overexpression of β3-tubulin.

Docking and Pharmacokinetic Studies for Screening Terpenoids from Erythroxylum Species as Anticancer Agents

Background: Cancer still remains a disease of concern with various side effects of synthetic chemotherapeutic agents. Hence, there is a continued need to develop safer therapies with fewer side effects. Erythroxylum species is a widely available source of various phytoconstituents, especially terpenoids. Objective: To carry out the docking studies of a few terpenoids on validated targets like EGFR, VEGFR, CDK, and tubulin protein which are overexpressed in many types of cancers, and to estimate the pharmacokinetic and drug-likeness properties of these molecules using in silico techniques. Materials: Protein structures were retrieved from Protein Data Bank, and the terpenoids were docked on each of the protein targets using Autodock 4.2. SwissADME was used to predict the pharmacokinetic and drug-likeness properties. Results: Compounds show good binding affinity and inhibition constant for all targets except for tubulin, where few ligands could bind. They exhibit an excellent pharmacokinetic profile, and no significant violations in drug-likeness parameters were observed. Conclusion: Compound 2 was found to be the most active agent against VEGFR, CDK, and tubulin, whereas compound 7 was most effective at EGFR. These compounds can be continued for further studies.

Biological evaluation of [4-(4-aminophenyl)-1-(4-fluorophenyl)-1H-pyrrol-3-yl](3,4,5-trimethoxyphenyl)methanone as potential antineoplastic agent in 2D and 3D breast cancer models.

Targeting tubulin polymerization and depolymerization represents a promising approach to treat solid tumors. In this study, we investigated the molecular mechanisms underlying the anticancer effects of a structurally novel tubulin inhibitor, [4-(4-aminophenyl)-1-(4-fluorophenyl)-1H-pyrrol-3-yl](3,4,5-trimethoxyphenyl)methanone (ARDAP), in two- and three-dimensional MCF-7 breast cancer models. At sub-cytotoxic concentrations, ARDAP showed a marked decrease in cell proliferation, colony formation, and ATP intracellular content in MCF-7 cells, by acting through a cytostatic mechanism. Additionally, drug exposure caused blockage of the epithelial-to-mesenchymal transition (EMT). In 3D cell culture, ARDAP negatively affected tumor spheroid growth, with inhibition of spheroid formation and reduction of ATP concentration levels. Notably, ARDAP exposure promoted the differentiation of MCF-7 cells by inducing: (i) expression decrease of Oct4 and Sox2 stemness markers, both in 2D and 3D models, and (ii) downregulation of the stem cell surface marker CD133 in 2D cell cultures. Interestingly, treated MCF7 cells displayed a major sensitivity to cytotoxic effects of the conventional chemotherapeutic drug doxorubicin. In addition, although exhibiting growth inhibitory effects against breast cancer cells, ARDAP showed insignificant harm to MCF10A healthy cells. Collectively, our results highlight the potential of ARDAP to emerge as a new chemotherapeutic agent or adjuvant compound in chemotherapeutic treatments.

Novel Tetrazole Derivatives Targeting Tubulin Endowed with Antiproliferative Activity against Glioblastoma Cells.

Increasing awareness of the structure of microtubules has made tubulin a relevant target for the research of novel chemotherapies. Furthermore, the particularly high sensitivity of glioblastoma multiforme (GBM) cells to microtubule disruption could open new doors in the search for new anti-GBM treatments. However, the difficulties in developing potent anti-tubulin drugs endowed with improved pharmacokinetic properties necessitates the expansion of medicinal chemistry campaigns. The application of an ensemble pharmacophore screening methodology helped to optimize this process, leading to the development of a new tetrazole-based tubulin inhibitor. Considering this scaffold, we have synthesized a new family of tetrazole derivatives that achieved remarkable antimitotic effects against a broad panel of cancer cells, especially against GBM cells, showing high selectivity in comparison with non-tumor cells. The compounds also exerted high aqueous solubility and were demonstrated to not be substrates of efflux pumps, thus overcoming the main limitations that are usually associated with tubulin binding agents. Tubulin polymerization assays, immunofluorescence experiments, and flow cytometry studies demonstrated that the compounds target tubulin and arrest cells at the G2/M phase followed by induction of apoptosis. The docking experiments agreed with the proposed interactions at the colchicine site and explained the structure-activity relationships.

Modified Podophyllotoxin Phenoxyacetamide Phenylacetate Derivatives: Tubulin/AKT1 Dual-Targeting and Potential Anticancer Agents for Human NSCLC.

Cancer is a major disease threatening human health worldwide, among which non-small-cell lung cancer (NSCLC) is the most deadly. Clinically, almost all anticancer drugs eventually fail to consistently benefit patients due to serious drug resistance. AKT is a key effector of the PI3K/AKT/mTOR pathway, which is closely related to the occurrence, development, and drug resistance of tumors. Herein, we first designed and synthesized 20 kinds of novel hybrid molecules targeting both tubulin and AKT based on a podophyllotoxin (PPT) skeleton through computer-aided drug design. By CCK8 assay, we screened the compound D1-1 (IC50 = 0.10 μM) with the strongest inhibitory activity against H1975 cells, and its activity was 100 times higher than PPT (IC50 = 12.56 μM) and 300 times higher than gefitinib (IC50 = 32.15 μM). Affinity analysis results showed that D1-1 not only retained the tubulin targeting of PPT but also showed strong AKT targeting. Subsequent pharmacological experiments showed that D1-1 significantly inhibited the proliferation and metastasis of H1975 cells and slightly induced their apoptosis by inhibiting both tubulin polymerization and the AKT pathway activation. Collectively, these data demonstrate that the novel hybrid molecule D1-1 may be an excellent lead compound for the treatment of human NSCLC as a dual inhibitor of tubulin and AKT.

Indolyl-chalcone derivatives trigger apoptosis in cisplatin-resistant mesothelioma cells through aberrant tubulin polymerization and deregulation of microtubule-associated proteins.

Malignant pleural mesothelioma (MPM) is a neoplasm with dismal prognosis and notorious resistance to the standard therapeutics cisplatin and pemetrexed. Chalcone derivatives are efficacious anti-cancer agents with minimal toxicity and have, therefore, gained pharmaceutical interest. Here, we investigated the efficacy of CIT-026 and CIT-223, two indolyl-chalcones (CITs), to inhibit growth and viability of MPM cells and defined the mechanism by which the compounds induce cell death. The effects of CIT-026 and CIT-223 were analyzed in five MPM cell lines, using viability, immunofluorescence, real-time cell death monitoring, and tubulin polymerization assays, along with siRNA knockdown. Phospho-kinase arrays and immunoblotting were used to identify signaling molecules that contribute to cell death. CIT-026 and CIT-223 were toxic in all cell lines at sub-micromolar concentrations, in particular in MPM cells resistant to cisplatin and pemetrexed, while normal fibroblasts were only modestly affected. Both CITs targeted tubulin polymerization via (1) direct interaction with tubulin and (2) phosphorylation of microtubule regulators STMN1, CRMP2 and WNK1. Formation of aberrant tubulin fibers caused abnormal spindle morphology, mitotic arrest and apoptosis. CIT activity was not reduced in CRMP2-negative and STMN1-silenced MPM cells, indicating that direct tubulin targeting is sufficient for toxic effects of CITs. CIT-026 and CIT-223 are highly effective inducers of tumor cell apoptosis by disrupting microtubule assembly, with only modest effects on non-malignant cells. CITs are potent anti-tumor agents against MPM cells, in particular cells resistant to standard therapeutics, and thus warrant further evaluation as potential small-molecule therapeutics in MPM.

Identification of pyrrolo[3′,4’:3,4]cyclohepta[1,2-d][1,2]oxazoles as promising new candidates for the treatment of lymphomas

Unsatisfactory outcomes for relapsed/refractory lymphoma patients prompt continuing efforts to develop new therapeutic strategies. Our previous studies on pyrrole-based anti-lymphoma agents led us to synthesize a new series of twenty-six pyrrolo[3′,4':3,4]cyclohepta[1,2-d] [1,2]oxazole derivatives and study their antiproliferative effects against a panel of four non-Hodgkin lymphoma cell lines. Several candidates showed significant anti-proliferative effects, with IC50's reaching the sub-micromolar range in at least one cell line, with compound 3z demonstrating sub-micromolar growth inhibitory effects towards the entire panel. The VL51 cell line was the most sensitive, with an IC50 value of 0.10 μM for 3z.Our earlier studies had shown that tubulin was a prominent target of many of our oxazole derivatives. We therefore examined their effects on tubulin assembly and colchicine binding. While 3u and 3z did not appear to target tubulin, good activity was observed with 3d and 3p.Molecular docking and molecular dynamics simulations allowed us to rationalize the binding mode of the synthesized compounds toward tubulin. All ligands exhibited a better affinity for the colchicine site, confirming their specificity for this binding pocket. In particular, a better affinity and free energy of binding was observed for 3d and 3p. This result was confirmed by experimental data, indicating that, although both 3d and 3p significantly affected tubulin assembly, only 3d showed activity comparable to that of combretastatin A-4, while 3p was about 4-fold less active.Cell cycle analysis showed that compounds 3u and especially 3z induced a block in G2/M, a strong decrease in S phase even at low compound concentrations and apoptosis through the mitochondrial pathway. Thus, the mechanism of action of 3u and 3z remains to be elucidated.Very high selectivity toward cancer cells and low toxicity in human peripheral blood lymphocytes were observed, highlighting the good potential of these agents in cancer therapy and encouraging further exploration of this compound class to obtain new small molecules as effective lymphoma treatments.

Structure optimization of an F-indole-chalcone (FC116) on 4-methoxyphenyl group and therapeutic potential against colorectal cancers with low cytotoxicity

Advanced metastatic colorectal cancers (CRCs) are regarded as a challenge in clinical cancer therapy. Our previous studies have demonstrated that a representative fluoro-substituted indole-chalcone (FC116), was obtained to display highly potent activity against CRC using multiple in vitro and in vivo mouse models by targeting microtubules. However, several problems, such as low dose tolerance and highly toxic to the brain and colon, low solubility unsuitable for intravenous (i.v.) administration, are still existed and limit further development. Herein, we developed two series of FC116 derivatives on the 4-methoxyphenyl group by a structure-based design strategy. Among them, FC11619 with an amino terminus maintained the in vitro cytotoxicity against HCT-116 CRC in a low nanomolar range. This compound could induce G2/M phase arrest via regulating cyclin B1 expression, produce excess reactive oxygen species (ROS), and target tubulin in CRC cells. In vivo, FC11619 significantly suppressed tumor growth, achieving 65.3 and 73.4 % at doses of 5 and 10 mg/kg/d (i.v., 21 d), which were much better than 54.1% of Taxol at 7 mg/kg. In addition, this compound showed better in vivo tolerance compared to that of FC116 (only 3 mg/kg tolerance, intraperitoneal, i.p.), and no major organ-related toxicity, especially no apparent degenerated neurons, intestinal obstruction in clinical Taxol standard therapy. Taken together, the 4-amino-substitutedphenyl indole-chalcones represent lead compounds as chemotherapy of CRC for further drug development in this field.

Design, Synthesis and Biological Evaluation of Imidazole-Substituted/Fused Aryl Derivatives Targeting Tubulin Polymerization as Anticancer Agents

AbstractThe development of new pharmacologically active molecules targeting tubulin polymerization has recently attracted great interest in research groups. In efforts to develop new potent anticancer compounds, imidazole-tethered/fused pharmacologically active aryl derivatives possessing different substitution patterns targeting tubulin polymerization have been rationally designed and synthesized. The target molecules (P1-5 and KG1-5) were synthesized by multistep syntheses involving the reaction of intermediate 2-aminophenyl-tethered imidazoles with appropriate reactants in the presence of p-TsOH under different conditions. The synthesized compounds displayed moderate to good cytotoxicity, comparable to that of colchicine, against four cancer cell lines (MCF-7, MD-MBA-231, A549, and HCT-116). Compounds P2 and P5, with an imidazoloquinoxaline moiety, emerged as potential leads with cytotoxicity profiles against these cell lines similar to colchicine. Compounds P2 and P5 arrested cell division at the G2/M phase and prevented cancerous cell growth through induced apoptosis. These results favored the hypothesis that the compounds might act by binding to the colchicine binding site, which was further confirmed with the help of a tubulin polymerization inhibition assay. The results encourage the further exploration of imidazoloquinoxalines as promising leads that deserve advanced clinical investigation.

Cytotoxic monoaryl furazanopyrazines with microtubule destabilizing activity in the sea urchin embryo model

Biological activity of monoaryl furazanopyrazines (FPs), known as high-energy molecules, is scarcely explored. A series of monoaryl FPs was synthesized by condensation of arylglyoxals with diaminofurazane. The targeted compounds at low micromolar concentrations inhibited growth of human cancer cells in NCI60 screen. Further evaluation using a sea urchin embryo model revealed that antiproliferative activity of monoaryl FPs could be associated with targeting tubulin and microtubule destabilization, systemic (nonspecific) toxicity, or both. Introduction of hydroxy group into pyrazine ring of monoaryl FPs yielded inactive molecules.

Sabizabulin, a Potent Orally Bioavailable Colchicine Binding Site Agent, Suppresses HER2+ Breast Cancer and Metastasis.

HER2+ breast cancer accounts for 15% of all breast cancer cases. Current frontline therapy for HER2+ metastatic breast cancer relies on targeted antibodies, trastuzumab and pertuzumab, combined with microtubule inhibitors in the taxane class (paclitaxel or docetaxel). It is well known that the clinical efficacy of taxanes is limited by the development of chemoresistance and hematological and neurotoxicities. The colchicine-binding site inhibitors (CBSIs) are a class of promising alternative agents to taxane therapy. Sabizabulin (formerly known as VERU-111) is a potent CBSI that overcomes P-gp-mediated taxane resistance, is orally bioavailable, and inhibits tumor growth and distant metastasis in triple negative breast cancer (TNBC). Herein, we demonstrate the efficacy of sabizabulin in HER2+ breast cancer. In vitro, sabizabulin inhibits the proliferation of HER2+ breast cancer cell lines with low nanomolar IC50 values, inhibits clonogenicity, and induces apoptosis in a concentration-dependent manner. In vivo, sabizabulin inhibits breast tumor growth in the BT474 (ER+/PR+/HER2+) xenograft model and a HER2+ (ER-/PR-) metastatic patient-derived xenograft (PDX) model, HCI-12. We demonstrate that sabizabulin is a promising alternative agent to target tubulin in HER2+ breast cancer with similar anti-metastatic efficacy to paclitaxel, but with the advantage of oral bioavailability and lower toxicity than taxanes.