Janus Compounds, 5-Chloro-N⁴-methyl-N⁴-aryl-9H-pyrimido[4,5-b]indole-2,4-diamines, Cause Both Microtubule Depolymerizing and Stabilizing Effects

Thermosensitive Betulinic Acid-Loaded Magnetoliposomes: A Promising Antitumor Potential for Highly Aggressive Human Breast Adenocarcinoma Cells Under Hyperthermic Conditions

PURPOSE

Breast cancer presents one of the highest rates of prevalence around the world. Despite this, the current breast cancer therapy is characterized by significant side effects and high risk of recurrence. The present work aimed to develop a new therapeutic strategy that may improve the current breast cancer therapy by developing a heat-sensitive liposomal nano-platform suitable to incorporate both anti-tumor betulinic acid (BA) compound and magnetic iron nanoparticles (MIONPs), in order to address both remote drug release and hyperthermia-inducing features. To address the above-mentioned biomedical purposes, the nanocarrier must possess specific features such as specific phase transition temperature, diameter below 200 nm, superparamagnetic properties and heating capacity. Moreover, the anti-tumor activity of the developed nanocarrier should significantly affect human breast adenocarcinoma cells.

METHODS

BA-loaded magnetoliposomes and corresponding controls (BA-free liposomes and liposomes containing no magnetic payload) were obtained through the thin-layer hydration method. The quality and stability of the multifunctional platforms were physico-chemically analysed by the means of RAMAN, scanning electron microscopy-EDAX, dynamic light scattering, zeta potential and DSC analysis. Besides this, the magnetic characterization of magnetoliposomes was performed in terms of superparamagnetic behaviour and heating capacity. The biological profile of the platforms and controls was screened through multiple in vitro methods, such as MTT, LDH and scratch assays, together with immunofluorescence staining. In addition, CAM assay was performed in order to assess a possible anti-angiogenic activity induced by the test samples.

RESULTS

The physico-chemical analysis revealed that BA-loaded magnetoliposomes present suitable characteristics for the purpose of this study, showing biocompatible phase transition temperature, a diameter of 198 nm, superparamagnetic features and heating capacity. In vitro results showed that hyperthermia induces enhanced anti-tumor activity when breast adenocarcinoma MDA-MB-231 cells were exposed to BA-loaded magnetoliposomes, while a low cytotoxic rate was exhibited by the non-tumorigenic breast epithelial MCF 10A cells. Moreover, the in ovo angiogenesis assay endorsed the efficacy of this multifunctional platform as a good strategy for breast cancer therapy, under hyperthermal conditions. Regarding the possible mechanism of action of this multifunctional nano-platform, the immunocytochemistry of the MCF7 and MDA-MB-231 breast carcinoma cells revealed a microtubule assembly modulatory activity, under hyperthermal conditions.

CONCLUSION

Collectively, these findings indicate that BA-loaded magnetoliposomes, under hyperthermal conditions, might serve as a promising strategy for breast adenocarcinoma treatment.

Pyrido-Fused Deazapurine Bases: Synthesis and Glycosylation of 4-Substituted 9H-Pyrido[2',3':4,5]- and Pyrido[4',3':4,5]pyrrolo[2,3-d]pyrimidines

Two isomeric sets of 4-substituted pyridopyrrolopyrimidine nucleobases were prepared through nucleophilic substitutions or cross-coupling reactions of 4-chloropyridopyrrolopyrimidines. The corresponding 4-amino-pyridopyrrolopyrimidines were glycosylated with 5-O-tritylribose using the modified Mitsunobu protocol. Several examples of the title heterocycles showed blue or green fluorescence. Testing of the pyridopyrrolopyrimidine nucleobases for the cytotoxic effect revealed micromolar activity of 4-benzofuryl derivatives in both series, preferentially in multidrug-resistant cancers.

4-Pyridinio-1,4-Dihydropyridines as Calcium Ion Transport Modulators: Antagonist, Agonist, and Dual Action

A set of six new 4-pyridinio-1,4-dihydropyridine (1,4-DHP) compounds has been synthesized. The calcium channel modulating activity of these compounds was evaluated in an aorta vascular smooth muscle cell line (A7R5), in an isolated rat aortic ring model, and in human neuroblastoma cell lines (SH-SY5Y). The antagonistic effect of these 1,4-DHP was tested by modulating the impact of carbachol-dependent mobilization of intracellular Ca²⁺ in SH-SY5Y cells. The intracellular free Ca²⁺ concentration was measured in confluent monolayers of SH-SY5Y cells and A7R5 cells with the Ca²⁺-sensitive fluorescent indicator Fluo-4 NW. Only four compounds showed calcium channel blocking activity in SH-SY5Y and A7R5 cells as well as in the aortic ring model. Among them, compound 3 was the most active calcium channel antagonist, which had 3 times higher activity on carbachol-activated SH-SY5Y cells than amlodipine. Two of the compounds were inactive. Compound 4 had 9 times higher calcium agonist activity than the classic DHP calcium agonist Bay K8644. The intracellular mechanism for the action of compound 4 using inhibitor analysis was elucidated. Nicotinic as well as muscarinic receptors were not involved. Sarcoplasmic reticulum (ER) Ca²⁺ (SERCA) stores were not affected. Ryanodine receptors (RyRs), another class of intracellular Ca²⁺ releasing channels, participated in the agonist response evoked by compound 4. The electrooxidation data suggest that the studied compounds could serve as antioxidants in OS.

Novel colchicine conjugate with unusual effect on the microtubules of cancer cells

Colchicine derivative bearing substituted bispidine moiety, namely N-{7-(3,7-Di-(tert-butoxycarbonyl)-1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonan-9-yl)-oxy-7-oxoheptanoyl}-N-deacetylcolchicine, was synthesized and tested for its effect on the net of microtubules (MT) in lung cancer cells A549. The compound induced not only MT depolymerization but stimulated the formation of small tubulin aggregates and long tubulin fibrils localized mainly around nuclei. The assemblies were morphologically different from tubulin clusters induced by structurally related anticancer agent tubuloclustin. The biotests data demonstrate that the depolymerization takes place for both pure tubulin and tubulin in cellulo, while fibrils are formed only in the cells. The research data of structure–activity relationship for several similar colchicine derivatives synthesized in the work give evidence for the proposition that the initial conjugate may interact not only with tubulin and MT in the cells, but also with MT-associated proteins, involved in the process of tubulin polymerization. The ability to affect simultaneously MAP – tubulin interactions opens attractive prospects in the design of novel anticancer agents.

Design and Antiproliferative Evaluation of Novel Sulfanilamide Derivatives as Potential Tubulin Polymerization Inhibitors

A series of sulfanilamide-1,2,3-triazole hybrids were designed by a molecular hybridization strategy and evaluated for antiproliferative activity against three selected cancer cell lines (MGC-803, MCF-7 and PC-3). The detailed structure-activity relationships for these sulfanilamide-1,2,3-triazole hybrids were investigated. All these sulfanilamide-1,2,3-triazole hybrids exhibited moderate to potent activity against all cell lines. In particular 4-methyl-N-((1-(3-phenoxybenzyl)-1H-1,2,3-triazol-4-yl)methyl)benzenesulfonamide (11f) showed the most potent inhibitory effect against PC-3 cells, with an IC₅₀ value of 4.08 μM. Furthermore, the tubulin polymerization inhibitory activity in vitro of compound 11f was 2.41 μM. These sulfanilamide hybrids might serve as bioactive fragments for developing more potent antiproliferative agents.