In vitro and in silico evaluation of P-glycoprotein inhibition through 99m Tc-methoxyisobutylisonitrile uptake

4-{3-[(Pyridin-4-ylmethyl)amino]-[1,2,4]triazolo[4,3-b][1,2,4]triazin-6-yl}phenol: An improved anticancer agent in hepatocellular carcinoma and a selective MDR1/MRP modulator

Hepatocellular carcinoma is the most common type of primary liver cancer. However, multidrug resistance (MDR) is a major obstacle to the effective chemotherapy of cancer cells. This report documents the rational design, synthesis, and biological evaluation of a novel series of triazolotriazines substituted with CH2NH-linked pyridine for use as dual c-Met/MDR inhibitors. Compound 12g with IC50 of 3.06 μM on HepG2 cells showed more potency than crizotinib (IC50 = 5.15 μM) in the MTT assay. In addition, 12g inhibited c-Met kinase at a low micromolar level (IC50 = 0.052 μM). 12g significantly inhibited P-gp and MRP1/2 efflux pumps in both cancerous HepG2 and BxPC3 cells starting from the lower concentrations of 3 and 0.3 µM, respectively. 12g did not inhibit MDR1 and MRP1/2 in noncancerous H69 cholangiocytes up to the concentration of 30 and 60 µM, respectively. Current results highlighted that cancerous cells were more susceptible to the effect of 12g than normal cells, in which the inhibition occurred only at the highest concentrations, suggesting a further interest in 12g as a selective anticancer agent. Overall, 12g, as a dual c-Met and P-gp/MRP inhibitor, is a promising lead compound for developing a new generation of anticancer agents.

Discovery of Chalcone-Based Hybrid Structures as High Affinity and Site-Specific Inhibitors against SARS-CoV-2: A Comprehensive Structural Analysis Based on Various Host-Based and Viral Targets

Previous studies indicated that natural-based chalcones have significant inhibitory effects on the coronavirus enzymes 3CLpro and PLpro as well as modulation of some host-based antiviral targets (HBATs). In this study, a comprehensive computational and structural study was performed to investigate the affinity of our compound library consisting of 757 chalcone-based structures (CHA-1 to CHA-757) for inhibiting the 3CLpro and PLpro enzymes and against twelve selected host-based targets. Our results indicated that CHA-12 (VUF 4819) is the most potent and multi-target inhibitor in our chemical library over all viral and host-based targets. Correspondingly, CHA-384 and its congeners containing ureide moieties were found to be potent and selective 3CLpro inhibitors, and benzotriazole moiety in CHA-37 was found to be a main fragment for inhibiting the 3CLpro and PLpro. Surprisingly, our results indicate that the ureide and sulfonamide moieties are integral fragments for the optimum 3CLpro inhibition while occupying the S1 and S3 subsites, which is fully consistent with recent reports on the site-specific 3CLpro inhibitors. Finding the multi-target inhibitor CHA-12, previously reported as an LTD4 antagonist for the treatment of inflammatory pulmonary diseases, prompted us to suggest it as a concomitant agent for relieving respiratory symptoms and suppressing COVID-19 infection.

Recent Advances on P-Glycoprotein (ABCB1) Transporter Modelling with In Silico Methods

ABC transporters play a critical role in both drug bioavailability and toxicity, and with the discovery of the P-glycoprotein (P-gp), this became even more evident, as it plays an important role in preventing intracellular accumulation of toxic compounds. Over the past 30 years, intensive studies have been conducted to find new therapeutic molecules to reverse the phenomenon of multidrug resistance (MDR) ), that research has found is often associated with overexpression of P-gp, the most extensively studied drug efflux transporter; in MDR, therapeutic drugs are prevented from reaching their targets due to active efflux from the cell. The development of P-gp inhibitors is recognized as a good way to reverse this type of MDR, which has been the subject of extensive studies over the past few decades. Despite the progress made, no effective P-gp inhibitors to reverse multidrug resistance are yet on the market, mainly because of their toxic effects. Computational studies can accelerate this process, and in silico models such as QSAR models that predict the activity of compounds associated with P-gp (or analogous transporters) are of great value in the early stages of drug development, along with molecular modelling methods, which provide a way to explain how these molecules interact with the ABC transporter. This review highlights recent advances in computational P-gp research, spanning the last five years to 2022. Particular attention is given to the use of machine-learning approaches, drug-transporter interactions, and recent discoveries of potential P-gp inhibitors that could act as modulators of multidrug resistance.

Effect of the Force Field on Molecular Dynamics Simulations of the Multidrug Efflux Protein P-Glycoprotein

Molecular dynamics (MD) simulations have been used extensively to study P-glycoprotein (P-gp), a flexible multidrug transporter that is a key player in the development of multidrug resistance to chemotherapeutics. A substantial body of literature has grown from simulation studies that have employed various simulation conditions and parameters, including AMBER, CHARMM, OPLS, GROMOS, and coarse-grained force fields, drawing conclusions from simulations spanning hundreds of nanoseconds. Each force field is typically parametrized and validated on different data and observables, usually of small molecules and peptides; there have been few comparisons of force field performance on large protein-membrane systems. Here we compare the conformational ensembles of P-gp embedded in a POPC/cholesterol bilayer generated over 500 ns of replicate simulation with five force fields from popular biomolecular families: AMBER 99SB-ILDN, CHARMM 36, OPLS-AA/L, GROMOS 54A7, and MARTINI. We find considerable differences among the ensembles with little conformational overlap, although they correspond to similar extents to structural data obtained from electron paramagnetic resonance and cross-linking studies. Moreover, each trajectory was still sampling new conformations at a high rate after 500 ns of simulation, suggesting the need for more sampling. This work highlights the need to consider known limitations of the force field used (e.g., biases toward certain secondary structures) and the simulation itself (e.g., whether sufficient sampling has been achieved) when interpreting accumulated results of simulation studies of P-gp and other transport proteins.

Itraconazole synergistically increases therapeutic effect of paclitaxel and 99mTc-MIBI accumulation, as a probe of P-gp activity, in HT-29 tumor-bearing nude mice

P-glycoprotein (P-gp), is an important efflux pump involved in chemotherapy resistance in human colon cancer. We investigated the efficacy of itraconazole as a P-gp inhibitor and its therapeutic synergistic relationship to paclitaxel through 99mTc-MIBI accumulation in HT-29 tumor-bearing nude mice. Histopathological screening along with in vitro experiments was done for further assessment. Itraconazole successfully inhibited P-gp mediated 99mTc-MIBI efflux, increasing its in vitro accumulation in itraconazole-receiving dishes. Notably, the co-administration of itraconazole with paclitaxel significantly enhanced the in vitro cytotoxicity effect of paclitaxel in itraconazole + paclitaxel wells containing HT-29 cells. Compared to the control, tumor volume in mice treated with itraconazole, paclitaxel and itraconazole +paclitaxel showed growth suppression approximately by 36.21, 60.02, and 73.3% respectively. And compared to paclitaxel group, the nude mice co-treated with paclitaxel and itraconazole showed suppression of tumor growth by about 33.31 % at the end of the treatment period. Also the biodistribution result showed that the co-administration of itraconazole with paclitaxel raised the mean tumor radioactivity accumulation compared to control and paclitaxel group. When given paclitaxel alone, the ID% of hepatic and cardiac tissue was reduced while co-administration of itraconazole with paclitaxel increased 99mTc-MIBI accumulation in these organs. Furthermore, the histopathological findings confirmed the biodistribution results. These results demonstrate that although monotherapy with itraconazole or paclitaxel has anti-tumor activity against HT-29 human colorectal cancer, a synergistic anti-tumor activity can be achieved when itraconazole is co-administered with paclitaxel. Also, 99mTc-MIBI is an effective radiotracer for monitoring response to treatment in MDR tumors.

Synthesis and Biological Assessment of 2-Hydroxyiminoethanones as Anti-Inflammatory and β-Amyloid Aggregation Inhibitors

Alzheimer’s disease (AD) is a neuroinflammatory based pathologic state in which β-amyloid aggregates are major devastating agents. In this study, a series of 2-hydroxyiminoethanones were synthesized and evaluated as anti-inflammatory in carrageenan and formalin tests and inhibitors of β-amyloid aggregation. Compounds 1-10b were synthesized through a two-step reaction. Results: Compounds 1-5b showed more β-amyloid disaggregation ability than reference drugs rifampicin and donepezil and compound 2b was the best compound in this series and could reduce the extent of amyloid aggregation to 50.9%. Interestingly, compounds 1b and 3b showed significant anti-inflammatory activity in carrageenan-induced paw edema compared to control group and equivalent to the reference drug indomethacin. 2-Hydeoxyiminoethanones are privileged scaffold for further drug research and development as anti-neuroinflammatory and neuroprotective agents.

Potentiation of Low-Dose Doxorubicin Cytotoxicity by Affecting P-Glycoprotein through Caryophyllane Sesquiterpenes in HepG2 Cells: an in Vitro and in Silico Study

Doxorubicin represents a valuable choice for different cancers, although the severe side effects occurring at the high effective dose limits its clinical use. In the present study, potential strategies to potentiate low-dose doxorubicin efficacy, including a metronomic schedule, characterized by a short and repeated exposure to the anticancer drug, and the combination with the natural chemosensitizing sesquiterpenes β-caryophyllene and β-caryophyllene oxide, were assessed in human hepatoma HepG2 cells. The involvement of P-glycoprotein (P-gp) in the HepG2–chemosensitization to doxorubicin was evaluated. Also, the direct interaction of caryophyllene sesquiterpenes with P-gp was characterized by molecular docking and dynamic simulation studies. A metronomic schedule allowed us to enhance the low-dose doxorubicin cytotoxicity and the combination with caryophyllane sesquiterpenes further potentiated this effect. Also, an increased intracellular accumulation of doxorubicin and rhodamine 123 induced by caryophyllane sesquiterpenes was found, thus suggesting their interference with P-gp function. A lowered expression of P-gp induced by the combinations, with respect to doxorubicin alone, was observed too. Docking studies found that the binding site of caryophyllane sesquiterpene was next to the ATP binding domain of P-gp and that β-caryophyllene possessed the stronger binding affinity and higher inhibition potential calculated by MM-PBSA. Present findings strengthen our hypothesis about the potential chemosensitizing power of caryophyllane sesquiterpenes and suggest that combining a chemosensitizer and a metronomic schedule can represent a suitable strategy to overcome drawbacks of doxorubicin chemotherapy while exploiting its powerful activity.

Synthesis and Anticancer Activity of Benzimidazole/Benzoxazole Substituted Triazolotriazines in Hepatocellular Carcinoma

BACKGROUND

Receptor Tyrosine Kinases (RTK) are the main family of cell surface receptors for growth factors, hormones and cytokines which are responsible for cell growth and differentiation and are considered as an important therapeutic target in cancer.

OBJECTIVE

The aim of this study was to design, synthesise and conduct the biological evaluation of benzimidazole/ benzoxazole substituted triazolotriazines as new anticancer agents.

METHODS

A series of benzimidazolyl and benzoxazolyl-linked triazolotriazines 8a-e and 9a-e were synthesized as receptor tyrosine kinase inhibitors. Target compounds were evaluated in HGF-induced cell proliferation assay in A549, MCF-7, HepG2 and MDA-MB-231 cancer cells.

RESULTS

Hepatocellular carcinoma was the most sensitive cell line towards the tested compounds and 8e was the most potent one on HepG2 cells with an IC50 value of 5.13µM which was close to crizotinib (HepG2 IC50 = 4.35µM) as a standard c-Met kinase inhibitor. c-Met kinase assay of 8e showed that this compound is not capable of inhibiting this enzyme and subsequently molecular docking confirmed the low affinity of 8e towards c- Met active site and its possible anticancer mechanism through VEGFR-2 inhibition.

CONCLUSION

Further in silico predictions revealed that 8e can be a drug candidate with favorable pharmacokinetic properties.