Discovery of Novel N-Heterocyclic-Fused Deoxypodophyllotoxin Analogues as Tubulin Polymerization Inhibitors Targeting the Colchicine-Binding Site for Cancer Treatment

Design and bio-evaluation of novel millepachine derivatives targeting tubulin colchicine binding site for treatment of osteosarcoma

Microtubules are recognized as an appealing target for cancer treatment. We designed and synthesized of novel tubulin colchicine binding site inhibitors based on millepachine. Biological evaluation revealed compound 5h exhibited significant antiproliferative activity against osteosarcoma cell U2OS and MG-63. And compound 5h also remarkably inhibited tubulin polymerization. Further investigations indicated compound 5h not only arrest U2OS cells cycle at the G2/M phases, but also induced U2OS cells apoptosis in dose-dependent manners. Moreover, compound 5h was verified to inhibit cell migration and angiogenesis of HUVECs, induce mitochondrial membrane potential decreased and promoted the elevation of ROS levels. Furthermore, compound 5h exhibited remarkable effects on tumor growth in vivo, and the TGI rate was up to 84.94 % at a dose of 20 mg/kg without obvious toxicity. These results indicated that 5h may be an appealing tubulin inhibitor for treatment of osteosarcoma.

Isolation and biomimetic synthesis of phenylpropionyl phenylethylamines from Chloranthus henryi

In this study, ten phenylpropionyl phenylethylamines, including five previously undescribed ones (1a/b, 2a/b, and 3), five known analogues (4-8), and two established phenylpropanoids precursors (9, 10) were isolated from the aerial parts of Chloranthus henryi Hemsl. Their structures, including absolute configurations, were determined by high-resolution mass spectrometry, enantio-separation, electronic circular dichroism calculation, and single crystal diffraction. Compounds 1a and 1b were the first examples of natural hetero-[2 + 2] cycloaddition products between phenylpropionyl phenylethylamine and phenylpropene. The plausible hetero-[2 + 2] biosynthesis pathway was confirmed by a photocatalytic biomimetic synthesis in eight steps, which also led to the production of three other potential natural homo-[2 + 2] adducts (1'a/b, 2', and 3'). Bioactivity screening indicated that these adducts bear medium inhibitory activity on nitric oxide generation, with IC50 values of 6-35 μM in RAW 264.7 macrophages.

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 Novel Isoquinoline Analogues as Dual Tubulin Polymerization/V-ATPase Inhibitors with Immunogenic Cell Death Induction

Cancer immunotherapy has revolutionized clinical advances in a variety of cancers. Due to the low immunogenicity of the tumor, only a few patients can benefit from it. Specific microtubule inhibitors can effectively induce immunogenic cell death and improve immunogenicity of the tumor. A series of isoquinoline derivatives based on the natural products podophyllotoxin and diphyllin were designed and synthesized. Among them, F10 showed robust antiproliferation activity against four human cancer cell lines, and it was verified that F10 exerted antiproliferative activity by inhibiting tubulin and V-ATPase. Further studies indicated that F10 is able to induce immunogenic cell death in addition to apoptosis. Meanwhile, F10 inhibited tumor growth in an RM-1 homograft model with enhanced T lymphocyte infiltration. These results suggest that F10 may be a promising lead compound for the development of a new generation of microtubule drugs.

Discovery of novel coumarin-based derivatives as inhibitors of tubulin polymerization targeting the colchicine binding site with potent anti-gastric cancer activities

In this work, a series of novel coumarin-based derivatives were designed and synthesized as tubulin polymerization inhibitors targeting the colchicine binding site, and their antiproliferative activities against MGC-803, HCT-116 and KYSE30 cells were evaluated. Among them, the compound I-3 (MY-1442) bearing a 6-methoxy-1,2,3,4-tetrahydroquinoline group exhibited most potent inhibitory activities on MGC-803 (IC50 = 0.034 μM), HCT-116 (IC50 = 0.081 μM) and KYSE30 cells (IC50 = 0.19 μM). Further mechanism studies demonstrated that compound I-3 (MY-1442) could directly bind to the colchicine binding site of β-tubulin to inhibit tubulin polymerization and microtubules at the cellular level. The results of molecular docking indicated there were well binding interactions between compound I-3 (MY-1442) and the colchicine binding site of β-tubulin. Compound I-3 (MY-1442) also exhibited effective anti-proliferation, pro-apoptosis, and anti-migration abilities against gastric cancer cells MGC-803. Additionally, compound I-3 (MY-1442) could regulate the expression of cell cycle- and apoptosis-related proteins. Importantly, compound I-3 (MY-1442) could significantly inhibit tumor growth in the MGC-803 xenograft tumor model with a TGI rate of 65.5 % at 30 mg/kg/day. Taken together, this work suggested that the coumarin skeleton exhibited great potential to be a key pharmacophore of tubulin polymerization inhibitors for the discovery of anticancer agents.

Design, synthesis and evaluation of dihydro-1H-indene derivatives as novel tubulin polymerisation inhibitors with anti-angiogenic and antitumor potency

Angiogenesis plays an important role in tumour generation and progression, which is used to supply nutrients and metastasis. Herein, a series of novel dihydro-1H-indene derivatives were designed and evaluated as tubulin polymerisation inhibitors by binding to colchicine site, exhibiting anti-angiogenic activities against new vessel forming. Through structure-activity relationships study, compound 12d was found to be the most potent derivative possessing the antiproliferative activity against four cancer lines with IC50 values among 0.028-0.087 µM. Compound 12d bound to colchicine site on tubulin and inhibited tubulin polymerisation in vitro. In addition, compound 12d induced cell cycle arrest at G2/M phase, stimulated cell apoptosis, inhibited tumour metastasis and angiogenesis. Finally, the results of in vivo assay suggested that compound 12d could prevent tumour generation, inhibit tumour proliferation and angiogenesis without obvious toxicity. Collectively, all these findings suggested that compound 12d is a novel tubulin polymerisation inhibitor deserving further research.

Rh(III)-Catalyzed Reaction of 4-Diazoisochroman-3-imines with (2-Formylaryl)boronic Acids To Access a Straightforward Construction of 5H-Isochromeno[3,4-c]isoquinolines

An Rh(III)-catalyzed one-pot synthesis of 5H-isochromeno[3,4-c]isoquinolines from readily available 4-diazoisochroman-3-imines and (2-formylphenyl)boronic acids is reported. The cascade annulation involves a Rh(III)-catalyzed cross-coupling and an intramolecular nucleophilic addition-elimination process. A series of biologically important 5H-isochromeno[3,4-c]isoquinolines were obtained in good to excellent yields. The method can be extended to synthesize 7H-isochromeno[3,4-b]thieno[3,2-d]pyridines and 7H-isochromeno[3,4-b]thieno[2,3-d]pyridines from the corresponding heteroaryl boronic acids.

Fused Imidazopyrazine-Based Tubulin Polymerization Inhibitors Inhibit Neuroblastoma Cell Function

Targeting the colchicine binding site on tubulin is a promising approach for cancer treatment to overcome the limitations of current tubulin polymerization inhibitors. New classes of colchicine binding site inhibitors (CBSIs) are continually being uncovered; however, balancing metabolic stability and cellular potency remains an issue that needs to be resolved. Therefore, we designed and synthesized a series of novel fused imidazopyridine and -pyrazine CBSIs and evaluated their cellular activity, metabolic stability, and tubulin-binding properties. Evidence shows that the imidazo[1,2-a]pyrazine series are effective against neuroblastoma cell lines marked by MYCN amplification. Further assessment shows that a combination of an imidazo[1,2-a]pyrazine core with a trimethoxyphenyl ring D results in the highest cellular activity and binding characteristics compared with a dichloromethoxyphenyl or difluoromethoxyphenyl ring D. However, the metabolic stability of compounds with a dichloromethoxyphenyl or difluoromethoxyphenyl ring D is significantly higher than that of those containing a trimethoxyphenyl ring D, suggesting that improved metabolic stability is achieved with a moderate impact on potency.

Discovery of a novel Coumarin-Dihydroquinoxalone derivative MY-673 as a tubulin polymerization inhibitor capable of inhibiting the ERK pathway with potent anti-gastric cancer activities

As a class of microtubule targeting agents, colchicine binding site inhibitors (CBSIs) are considered as promising drug candidates for cancer therapy. However, due to adverse reactions, there are currently no CBSIs approved by FDA for cancer treatment. Therefore, extensive efforts are still encouraged to find novel CBSIs with different chemical structures and better anticancer efficacies. In this work, we designed and synthesized a new coumarin-dihydroquinoxalone derivative, MY-673, and evaluated its anticancer potency in vitro and in vivo. We confirmed that MY-673 was a potent CBSI that it not only inhibited tubulin polymerization, but also exhibited significant inhibitory potency on the growth of 13 cancer cells with IC₅₀ values from 11.7 nM to 395.9 nM. Based on the results of kinase panel screening, MY-673 could inhibit ERK (extracellular regulated protein kinases) pathways-related kinases. We further confirmed that MY-673 could inhibit ERK signaling pathway in MGC-803 and HGC-27 cells, and then affected the expression level of SMAD4 protein in TGF-β (transforming growth factor β) /SMAD (small mother against decapentaplegic) signaling pathway using the western blotting assay. In addition, compound MY-673 could effectively inhibit cell proliferation, migration and induce cell apoptosis. We also further confirmed the in vivo efficacy of MY-673 in inhibiting tumor growth using the MGC-803 xenograft tumor model. At 20 mg/kg, the TGI rate was 85.9%, and it did not cause obvious toxicity to the main organs of mice. Together, the results we report here indicated that MY-673 was a promising CBSI for cancer treatment, which was capable of inhibiting the ERK pathway with potent antiproliferative activities in vitro and in vivo.