A class of novel tubulin polymerization inhibitors exert effective anti-tumor activity via mitotic catastrophe

Design, synthesis, and bioevaluation of 1h-pyrrolo[3,2-c]pyridine derivatives as colchicine-binding site inhibitors with potent anticancer activities

A new series of 1H-pyrrolo[3,2-c]pyridine derivatives were designed and synthesised as colchicine-binding site inhibitors. Preliminary biological evaluations showed that most of the target compounds displayed moderate to excellent antitumor activities against three cancer cell lines (HeLa, SGC-7901, and MCF-7) in vitro. Among them, 10t exhibited the most potent activities against three cancer cell lines with IC50 values ranging from 0.12 to 0.21 μM. Tubulin polymerisation experiments indicated that 10t potently inhibited tubulin polymerisation at concentrations of 3 μM and 5 μM, and immunostaining assays revealed that 10t remarkably disrupted tubulin microtubule dynamics at a concentration of 0.12 μM. Furthermore, cell cycle studies and cell apoptosis analyses demonstrated that 10t at concentrations of 0.12 μM, 0.24 μM, and 0.36 μM significantly caused G2/M phase cell cycle arrest and apoptosis. The results of molecular modelling studies suggested that 10t interacts with tubulin by forming hydrogen bonds with colchicine sites Thrα179 and Asnβ349. In addition, the prediction of physicochemical properties disclosed that 10t conformed well to the Lipinski's rule of five.

Perspectives and mechanisms for targeting mitotic catastrophe in cancer treatment

Mitotic catastrophe is distinct from other cell death modes due to unique nuclear alterations characterized as multi and/or micronucleation. Mitotic catastrophe is a common and virtually unavoidable consequence during cancer therapy. However, a comprehensive understanding of mitotic catastrophe remains lacking. Herein, we summarize the anticancer drugs that induce mitotic catastrophe, including microtubule-targeting agents, spindle assembly checkpoint kinase inhibitors, DNA damage agents and DNA damage response inhibitors. Based on the relationships between mitotic catastrophe and other cell death modes, we thoroughly evaluated the roles played by mitotic catastrophe in cancer treatment as well as its advantages and disadvantages. Some strategies for overcoming its shortcomings while fully utilizing its advantages are summarized and proposed in this review. We also review how mitotic catastrophe regulates cancer immunotherapy. These summarized findings suggest that the induction of mitotic catastrophe can serve as a promising new therapeutic approach for overcoming apoptosis resistance and strengthening cancer immunotherapy.

Exploring Pyrrolo-Fused Heterocycles as Promising Anticancer Agents: An Integrated Synthetic, Biological, and Computational Approach

Five new series of pyrrolo-fused heterocycles were designed through a scaffold hybridization strategy as analogs of the well-known microtubule inhibitor phenstatin. Compounds were synthesized using the 1,3-dipolar cycloaddition of cycloimmonium N-ylides to ethyl propiolate as a key step. Selected compounds were then evaluated for anticancer activity and ability to inhibit tubulin polymerization in vitro. Notably, pyrrolo[1,2-a]quinoline 10a was active on most tested cell lines, performing better than control phenstatin in several cases, most notably on renal cancer cell line A498 (GI₅₀ 27 nM), while inhibiting tubulin polymerization in vitro. In addition, this compound was predicted to have a promising ADMET profile. The molecular details of the interaction between compound 10a and tubulin were investigated through in silico docking experiments, followed by molecular dynamics simulations and configurational entropy calculations. Of note, we found that some of the initially predicted interactions from docking experiments were not stable during molecular dynamics simulations, but that configurational entropy loss was similar in all three cases. Our results suggest that for compound 10a, docking experiments alone are not sufficient for the adequate description of interaction details in terms of target binding, which makes subsequent scaffold optimization more difficult and ultimately hinders drug design. Taken together, these results could help shape novel potent antiproliferative compounds with pyrrolo-fused heterocyclic cores, especially from an in silico methodological perspective.

Design, Synthesis, and Biological Evaluation of Heterocyclic-Fused Pyrimidine Chemotypes Guided by X-ray Crystal Structure with Potential Antitumor and Anti-multidrug Resistance Efficacy Targeting the Colchicine Binding Site

Herein, a series of quinazoline and heterocyclic fused pyrimidine analogues were designed and synthesized based on the X-ray co-crystal structure of lead compound 3a, showing efficacious antitumor activities. Two analogues, 15 and 27a, exhibited favorable antiproliferative activities, which were more potent than lead compound 3a by 10-fold in MCF-7 cells. In addition, 15 and 27a exhibited potent antitumor efficacy and tubulin polymerization inhibition in vitro. 15 reduced the average tumor volume by 80.30% (2 mg/kg) in the MCF-7 xenograft model and 75.36% (4 mg/kg) in the A2780/T xenograft model, respectively. Most importantly, supported by structural optimization and Mulliken charge calculation, X-ray co-crystal structures of compounds 15, 27a, and 27b in complex with tubulin were resolved. In summary, our research provided the rational design strategy of colchicine binding site inhibitors (CBSIs) based on X-ray crystallography with antiproliferation, antiangiogenesis, and anti-multidrug resistance properties.

Discovery and biological evaluation of 4,6-pyrimidine analogues with potential anticancer agents as novel colchicine binding site inhibitors

Novel 4,6-pyrimidine analogues were designed and synthesized as colchicine binding site inhibitors (CBSIs) with potent antiproliferative activities. Among them, compound 17j has the most potent activities against 6 human cancer cell lines with IC₅₀ values from 1.1 nM to 4.4 nM, which was 76 times higher than the lead compound 3 in A549 cells. The co-crystal structure of 17j in complex with tubulin confirms the key binding mode at the colchicine binding site. Moreover, 17j inhibited the tubulin polymerization in biochemical assays, depolymerized cellular microtubules, induced the G2/M arrest, inhibited the cell migration, and promoted the initiation of apoptosis. In vivo, 17j effectively inhibits primary tumor growth with tumor growth inhibition rates of 42.51% (5 mg/kg) and 65.42% (10 mg/kg) in A549 xenograft model. Taken together, 17j represents a promising new generation of CBSIs.

Design and synthesis of new trimethoxylphenyl-linked combretastatin analogues loaded on diamond nanoparticles as a panel for ameliorated solubility and antiproliferative activity

A new series of vinyl amide-, imidazolone-, and triazinone-linked combretastatin A-4 analogues have been designed and synthesised. These compounds have been evaluated for their cytotoxic activity against MDA-MB-231 breast cancer cells. The triazinone-linked combretastatin analogues (6 and 12) exhibited the most potent cytotoxic activity, in sub-micromolar concentration compared with combretastatin A-4 as a reference standard. The results of β-tubulin polymerisation inhibition assay appear to correlate well with the ability to inhibit β-tubulin polymerisation. Additionally, these compounds were subjected to biological assays relating to cell cycle aspects and apoptosis induction. In addition, the most potent compound 6 was loaded on PEG-PCL modified diamond nanoparticles (PEG-PCL-NDs) and F4 was picked as the optimum formula. F4 exhibited enhanced solubility and release over the drug suspension. In the comparative cytotoxic activity, PEG-PCL modified F4 was capable of diminishing the IC50 by around 2.89 times for nude F4, while by 3.48 times relative to non-formulated compound 6.

Discovery of pyrimidine-bridged CA-4 CBSIs for the treatment of cervical cancer in combination with cisplatin with significantly reduced nephrotoxicity

A series of pyrimidine-bridged CA-4 derivatives (9a-u) targeting colchicine site were designed, synthesized and evaluated. Among them, the most potent compound 9j showed favorable anti-proliferative activities against a panel of cervical cancer cells (IC₅₀ = 0.09-0.15 μM) and tubulin polymerization inhibitory activity (IC₅₀ = 4.6 μM). Meanwhile, compound 9j exhibited superior anti-proliferative activity against cisplatin-resistant HeLa/DDP and SiHa/DDP cells than CA-4 and cisplatin. Particularly, the combination of 30 mg/kg 9j with 3 mg/kg cisplatin resulted in a 73% tumor suppression rate in HeLa xenograft model and reduced the renal dysfunction and injuries caused by high doses of cisplatin. Moreover, 9j was highly selective over the normal human proximal tubular cells (HK-2 cells, IC₅₀ = 188 μM). Mechanism studies revealed that 9j could disrupt tubulin polymerization and vasculature, arrest the cell cycle at the G₂/M phase, induce apoptosis, and suppress clonogenesis and migration in HeLa cells. Further druggability characterization in terms of pharmacokinetic profile, acute toxicity, and hERG inhibition confirmed 9j could serve as a promising and safe combination agent for cervical cancer therapy.

Pyrazoline derivatives as tubulin polymerization inhibitors with one hit for Vascular Endothelial Growth Factor Receptor 2 inhibition

In this work, to check the effect of the transposition of the rings in typical patterns, a series of pyrazoline derivatives 3a-3t bearing the characteristic 3,4,5-trimethoxy phenyl and thiophene moieties were synthesized and evaluated as tubulin polymerization inhibitors. Basically, as the concise output of our design, a majority of the synthesized compounds showed potency in inhibiting the tubulin polymerization. The top hit, 3q, exhibited potent anti-proliferation activity on cancer cell lines. It was comparable on tubulin-polymerization inhibition with the positive control Colchicine but lower toxic. The VEGFR2 inhibitory potency was introduced occasionally. The flow cytometry assay confirmed the apoptotic procedure and the confocal imaging revealed the tubulin-microtubule dynamics pattern. The anti-cancer mechanism of 3q was similar to Colchicine but not exactly the same on forming multi-polar spindles. The docking simulation visualized the possible binding patterns of 3q into tubulin and VEGFR2, respectively. The results inferred that further investigations on the transposition of the rings might lead to the improvement of tubulin polymerization inhibitory activity and the steadily introduction of the VEGFR2 inhibition.

Discovery of Anticancer Agents from 2-Pyrazoline-Based Compounds

As nitrogen-containing five-membered heterocyclic structural units, the substituted pyrazole derivatives have a broad spectrum of pharmacological activities, especially 4,5-dihydro-1H-pyrazoles that also commonly known as 2-pyrazolines. Since 2010, considerable studies have been found that the 2-pyrazoline derivatives possess potent anticancer activities. In the present review, it covers the pyrazoline derivatives reported by literature from 2010 till date (2010-2019). This review aims to establish the relationship between the anticancer activities variation and different substituents introduced into a 2-pyrazoline core, which could provide important pharmacophore clues for the discovery of new anticancer agents containing 2-pyrazoline scaffold.

Pyrazol(in)e derivatives of curcumin analogs as a new class of anti-Trypanosoma cruzi agents

Aim: We report the synthesis and biological evaluation of a small library of 15 functionalized 3-styryl-2-pyrazolines and pyrazoles, derived from curcuminoids, as trypanosomicidal agents. Methods & results: The compounds were prepared via a cyclization reaction between the corresponding curcuminoids and the appropriate hydrazines. All of the derivatives synthesized were investigated for their trypanosomicidal activities. Compounds 4a and 4e showed significant activity against epimastigotes of Trypanosoma cruzi, with IC₅₀ values of 5.0 and 4.2 μM, respectively, accompanied by no toxicity to noncancerous mammalian cells. Compound 6b was found to effectively inhibit T. cruzi triosephosphate isomerase. Conclusion: The up to 16-fold higher potency of these derivatives compared with their curcuminoid precursors makes them a promising new family of T. cruzi inhibitors.

Tubulin Inhibitors Binding to Colchicine-Site: A Review from 2015 to 2019

Due to the three domains of the colchicine-site which is conducive to the combination with small molecule compounds, colchicine-site on the tubulin has become a common target for antitumor drug development, and accordingly, a large number of tubulin inhibitors binding to the colchicine-site have been reported and evaluated over the past years. In this study, tubulin inhibitors targeting the colchicine-site and their application as antitumor agents were reviewed based on the literature from 2015 to 2019. Tubulin inhibitors were classified into ten categories according to the structural features, including colchicine derivatives, CA-4 analogs, chalcone analogs, coumarin analogs, indole hybrids, quinoline and quinazoline analogs, lignan and podophyllotoxin derivatives, phenothiazine analogs, N-heterocycle hybrids and others. Most of them displayed potent antitumor activity, including antiproliferative effects against Multi-Drug-Resistant (MDR) cell lines and antivascular properties, both in vitro and in vivo. In this review, the design, synthesis and the analysis of the structure-activity relationship of tubulin inhibitors targeting the colchicine-site were described in detail. In addition, multi-target inhibitors, anti-MDR compounds, and inhibitors bearing antitumor activity in vivo are further listed in tables to present a clear picture of potent tubulin inhibitors, which could be beneficial for medicinal chemistry researchers.

Progress of tubulin polymerization activity detection methods

Tubulin, an important target in tumor therapy, is one of the hotspots in the field of antineoplastic drugs in recent years, and it is of great significance to design and screen new inhibitors for this target. Natural products and chemical synthetic drugs are the main sources of tubulin inhibitors. However, due to the variety of compound structure types, it has always been difficult for researchers to screen out polymerization inhibitors with simple operation, high efficiency and low cost. A large number of articles have reported the screening methods of tubulin inhibitors and their biological activity. In this article, the biological activity detection methods of tubulin polymerization inhibitors are reviewed. Thus, it provides a theoretical basis for the further study of tubulin polymerization inhibitors and the selection of methods for tubulin inhibitors.

Discovery of new indole-based 1,2,4-triazole derivatives as potent tubulin polymerization inhibitors with anticancer activity

Thirty-six novel indole-based 1,2,4-triazole derivatives were designed and synthesized through the molecular hybrid strategy.

Insight on [1,3]thiazolo[4,5-e]isoindoles as tubulin polymerization inhibitors

A series of [1,3]thiazolo[4,5-e]isoindoles has been synthesized through a versatile and high yielding multistep sequence. Evaluation of the antiproliferative activity of the new compounds on the full NCI human tumor cell line panel highlighted several compounds that are able to inhibit tumor cell proliferation at micromolar-submicromolar concentrations. The most active derivative 11g was found to cause cell cycle arrest at the G2/M phase and induce apoptosis in HeLa cells, following the mitochondrial pathway, making it a lead compound for the discovery of new antimitotic drugs.

Molecular targets and anticancer activity of quinoline-chalcone hybrids: literature review

α,β-Unsaturated chalcone moieties and quinoline scaffolds play an important role in medicinal chemistry, especially in the identification and development of potential anticancer agents. The multi-target approach or hybridization is considered as a promising strategy in drug design and discovery. Hybridization may improve the affinity and potency while simultaneously decreasing the resistance and/or side effects. The conjugation of quinolines with chalcones has been a promising approach to the identification of potential anticancer agents. Most of these hybrids showed anticancer activities through the inhibition of tubulin polymerization, different kinases, topoisomerases, or by affecting DNA cleavage activity. Accordingly, this class of compounds can be classified based on their molecular modes of action. In this article, the quinolone-chalcone hybrids with potential anticancer activity have been reviewed. This class of compounds might be helpful for the design, discovery and development of new and potential multi-target anticancer agents or drugs.

Design, synthesis and biological evaluation of novel 5,6,7-trimethoxy-N-aryl-2-styrylquinolin-4-amines as potential anticancer agents and tubulin polymerization inhibitors

A new series of styrylquinolines was designed and synthesized as anticancer agents and tubulin polymerization inhibitors. The in vitro anticancer activity of the synthesized quinolines was evaluated against four human cancer cell lines including A-2780 (human ovarian carcinoma), A-2780/RCIS (cisplatin resistant human ovarian carcinoma), MCF-7 (human breast cancer cells), MCF-7/MX (mitoxantrone resistant human breast cancer cells) and normal Huvec cells. Generally, among the forty-eight newly synthesized quinolines, compounds possessing N-trimethoxy phenyl showed stronger cytotoxic activity with IC₅₀ values ranging from 0.38 to 5.01 μM against all four cancer cell lines. Compounds 9VII-c and 9IV-c showed significant cytotoxic activity on A-2780 cancer cells, stronger than the other compounds and comparable to reference drug CA-4. Compound 9IV-c possessing 3,4-dimethoxystyryl and N-trimethoxy phenyl groups demonstrated potent cytotoxic effects with IC₅₀ values ranging from 0.5 to 1.66 µM on resistant cancer cells as well as their parental cells. Annexin V binding staining assay in A-2780 and MCF-7/MX cancer cells, revealed that compound 9IV-c induced early and late apoptosis. Compounds 9IV-c and 9VII-b, inhibited tubulin polymerization similar to CA4. Finally, molecular docking studies of 9IV-c and 9VII-b into the colchicine-binding site of tubulin displayed the possible interactions of these compounds with tubulin.

Design, synthesis and biological evaluation of resveratrol-cinnamoyl derivates as tubulin polymerization inhibitors targeting the colchicine binding site

A novel series of resveratrol-cinnamoyl hybrids as tubulin polymerization inhibitors were designed and synthesized, and evaluated for their anti-proliferative activities against A549, MCF-7, HepG2, HeLa and MDA-MB-231 five cancer cell lines. Most designed compounds showed better anti-proliferative activities. Particularly, compound 6h exhibited the potent anti-proliferative activities with the IC₅₀ value of 0.12, 0.016, 0.44, 0.37 and 0.78 μΜ against A549, MCF-7, HepG2, HeLa and MDA-231, respectively, which was superior to that of reference drug colchicine. Besides, compound 6h displayed a remarkable inhibition of tubulin polymerization and a great potency to compete with [³H] colchicine in binding to tubulin. Further studies indicated that compound 6h could induce the MCF-7 cells arrest in the G2/M phase. What' more, compound 6h induced cell apoptosis in a dose-dependent manner, and regulated the expression level of apoptosis-related proteins. These results revealed that compound 6h is a promising tubulin polymerization inhibitor for treatment of cancer and it is worthy of further exploitation.

Highlights in Resistance Mechanism Pathways for Combination Therapy

Combination chemotherapy has been a mainstay in cancer treatment for the last 60 years. Although the mechanisms of action and signaling pathways affected by most treatments with single antineoplastic agents might be relatively well understood, most combinations remain poorly understood. This review presents the most common alterations of signaling pathways in response to cytotoxic and targeted anticancer drug treatments, with a discussion of how the knowledge of signaling pathways might support and orient the development of innovative strategies for anticancer combination therapy. The ultimate goal is to highlight possible strategies of chemotherapy combinations based on the signaling pathways associated with the resistance mechanisms against anticancer drugs to maximize the selective induction of cancer cell death. We consider this review an extensive compilation of updated known information on chemotherapy resistance mechanisms to promote new combination therapies to be to discussed and tested.

Anticancer sulfonamide hybrids that inhibit bladder cancer cells growth and migration as tubulin polymerisation inhibitors

Novel sulfonamide-dithiocarbamate hybrids were designed and synthesised via the molecular hybridisation strategy. Among them, compound 13d displayed a potent activity with IC₅₀ values of 0.9, 0.7, 1.9 and 2.6 µM against UM-UC-3, RT-112, RT4 and T24. Compound 13d inhibited the migration and regulated the migration-related markers (E-cadherin, N-cadherin, Vimentin, Snail and Slung) against RT-112 cells in a concentration dependent manner. By the tubulin polymerisation assay in vitro and immunostaining assay, compound 13d was identified as a novel tubulin polymerisation inhibitor. Intragastric administration of compound 13d could inhibit the growth of RT-112 cells in vivo in a xenograft mouse model with the low toxicity, indicating that it may be a leading candidate with antitumor properties to treat bladder cancer.