Frequently asked questions in drug combinations and the mass-action law-based answers

c-MET tyrosine kinase inhibitors reverse multidrug resistance in breast cancer cells by targeting ABCG2 transporter

BACKGROUND

Overcoming multidrug resistance (MDR), which is often caused by the overexpression of ATP binding cassette (ABC) transporters in cancer cells remains a major challenge for cancer treatment. Receptor tyrosine kinase inhibitors have demonstrated potential in reversing MDR. This study aimed to investigate the effects of c-MET RTKIs on the reversal of MDR induced by ABCG2 in breast cancer cells.

METHODS

MTT assay was employed to assess antiproliferative activity of c-MET inhibitors, including cabozantinib, crizotinib, and PHA665752. The accumulation of the fluorescent probe mitoxantrone was evaluated by flow cytometry. The drug-drug interaction in combination treatments was analyzed using CalcuSyn software.

RESULTS

The combination of cabozantinib, crizotinib, and PHA665752 with mitoxantrone resulted in synergistic effects in MDR cells. This was demonstrated by the mean CI values of 0.32 ± 0.07, 0.53 ± 0.05, and 0.59 ± 0.03, respectively. In the same cells, c-MET inhibitors enhanced the accumulation of mitoxantrone, with accumulation ratios ranging from 1.6 to 3.8, while no change was found in parental MCF-7 cells. Computational analysis revealed that the drug-binding region of ABCG2 transporters could be a viable target for these compounds.

CONCLUSION

c-MET inhibitors hold potential as effective agents for reversing MDR in ABCG2-medicated drug-resistant cancer cells.

Apoptotic Effect of Combinations of T-2, HT-2, and Diacetoxyscirpenol on Human Jurkat T Cells

Trichothecene type A mycotoxins, such as T-2, HT-2, and diacetoxyscirpenol (DAS), are known to induce cytotoxicity and apoptosis in different cell types. As all three Fusarium toxins may occur concomitantly in a given food or feed commodity, there is growing interest in the effect of such mycotoxin mixtures. This study aimed to identify the toxic interactions among T-2, HT-2, and DAS in a human Jurkat cell model. As a first step, an MTT assay was used to assess cytotoxicity after 24 h of cell exposure to individual mycotoxins and their mixtures. The results were used to calculate the combination index (CI), which indicates the nature of the mycotoxin interactions. In Jurkat T cells, the toxicity ranking for the individual mycotoxins was T-2 > HT-2 > DAS. The CI values of the dual and triple mycotoxin combinations calculated from the results of the MTT and reactive oxygen species assays showed synergistic effects at low concentrations and an apparent antagonism at very high concentrations for all combinations. The additional cytometric analyses confirmed the synergistic effects, as expected, following co-exposure to the three tested trichothecenes. As the lower toxin concentrations investigated reflect natural contamination levels in food and feeds, the synergistic effects identified should be considered in risk characterization for trichothecene exposure in humans and animals.

Combined Cytotoxic Effects of the Fungicide Azoxystrobin and Common Food-Contaminating Mycotoxins

This study assessed the cytotoxicity of the individual and combined exposure to the fungicide azoxystrobin (AZX) and the three common mycotoxins found in food: ochratoxin A (OTA), deoxynivalenol (DON), and T-2 toxin. Cytotoxic effects were evaluated using the resazurin and MTT assays in human hepatocarcinoma (HepG2) cells after 24 h of exposure, and the type of interaction between the compounds was determined using the isobologram method. Results showed that T-2 was the most cytotoxic compound, followed by DON, OTA, and AZX. The compound ratios in the mixture were calculated using three sublethal concentrations (IC50/2, IC50/4, and IC50/8) to achieve equal toxicity for each compound. Interaction analysis revealed that the nature of the interaction varied across components and concentrations. The AZX and DON mixture produced an antagonistic effect at all the analyzed effect levels. AZX and OTA or T2 mixtures, and tertiary combinations displayed antagonism at low effect values but additivity at high effect levels. Importantly, the quaternary mixture demonstrated synergism at all the effect levels. These findings highlight that the co-occurrence of fungicides and mycotoxins in food commodities can lead to complex exposure scenarios that may result in combined toxic effects on the organism.

NSC95397 Is a Novel HIV-1 Latency-Reversing Agent

The latent viral reservoir represents one of the major barriers to curing HIV-1. Focus on the "kick and kill" (also called "shock and kill") approach, in which virus expression is reactivated, and then cells producing virus are selectively depleted, has led to the discovery of many latency-reversing agents (LRAs) that have furthered our understanding of the mechanisms driving HIV-1 latency and latency reversal. Thus far, individual compounds have yet to be robust enough to work as a therapy, highlighting the importance of identifying new compounds that target novel pathways and synergize with known LRAs. In this study, we identified a promising LRA, NSC95397, from a screen of ~4250 compounds. We validated that NSC95397 reactivates latent viral transcription and protein expression from cells with unique integration events and across different latency models. Co-treating cells with NSC95397 and known LRAs demonstrated that NSC95397 synergizes with different drugs under both standard normoxic and physiological hypoxic conditions. NSC95397 does not globally increase open chromatin, and bulk RNA sequencing revealed that NSC95397 does not greatly increase cellular transcription. Instead, NSC95397 downregulates pathways key to metabolism, cell growth, and DNA repair-highlighting the potential of these pathways in regulating HIV-1 latency. Overall, we identified NSC95397 as a novel LRA that does not largely alter global transcription, shows potential for synergy with known LRAs, and may act through novel pathways not previously recognized for their ability to modulate HIV-1 latency.

Antidepressant Sertraline Synergistically Enhances Paclitaxel Efficacy by Inducing Autophagy in Colorectal Cancer Cells

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. It is important to discover new therapeutic regimens for treating CRC. Depression is known to be an important complication of cancer diseases. Repurposing antidepressants into anticancer drugs and exploring the combinational efficacy of antidepressants and chemotherapy are potentially good options for developing CRC treatment regimens. In this study, sertraline, an antidepressant drug, and paclitaxel, an anticancer drug, were chosen to study their antitumor effects in the treatment of colorectal cancer, alone or in combination, and to explore their underlying mechanisms. The data showed that sertraline exerted a dose-dependent cytotoxic effect on MC38 and CT26 colorectal cancer cell lines with IC50 values of 10.53 μM and 7.47 μM, respectively. Furthermore, sertraline synergistically sensitized chemotherapeutic agent paclitaxel efficacy in CRC cells with combination index (CI) values at various concentrations consistently lower than 1. Sertraline remarkably augmented paclitaxel-induced autophagy by increasing autophagosome formation indicated by elevated LC3-II/I ratio and promoting autophagic flux by degrading autophagy cargo receptor SQSTM1/p62, which may explain the synergistically cytotoxic effect of sertraline and paclitaxel combination therapy on CRC cells. This study provides important evidence to support repurposing sertraline as an anticancer agent and suggests a novel combinational regimen for effectively treating CRC as well as in the simultaneous treatment of CRC and depression.

Multiaction Pt(IV) Prodrugs Releasing Cisplatin and Dasatinib Are Potent Anticancer and Anti-Invasive Agents Displaying Synergism between the Two Drugs

Herein, we describe the general design, synthesis, characterization, and biological activity of new multitargeting Pt(IV) prodrugs that combine antitumor cisplatin and dasatinib, a potent inhibitor of Src kinase. These prodrugs exhibit impressive antiproliferative and anti-invasive activities in tumor cell lines in both two-dimensional (2D) monolayers of cell cultures and three-dimensional (3D) spheroids. We show that the cisplatin moiety and dasatinib in the investigated Pt(IV) complexes are both involved in the mechanism of action in MCF7 breast cancer cells and act synergistically. Thus, combining dasatinib and cisplatin into one molecule, compared to using individual components in a mix, may bring several advantages, such as significantly higher activity in cancer cell lines and higher selectivity for tumor cells. Most importantly, Pt(IV)-dasatinib complexes hold significant promise for potential anticancer therapies by targeting epithelial-mesenchymal transition, thus preventing the spread and metastasis of tumors, a value unachievable by a simple combination of both individual components.

Enhancing therapeutic efficacy in breast cancer: a study on the combined cytotoxic effects of doxorubicin and MPC-3100

PURPOSE

Combination therapy is a strategy aimed at the combined use of agents targeting different mechanisms in cancer treatment. This study aimed to examine the cytotoxic and apoptotic effects of the traditional chemotherapeutic agent doxorubicin (DOX) and the next-generation HSP90 inhibitor MPC-3100 on breast cancer cell lines.

METHODS

Firstly, molecular docking analyses were performed, and then the MTT test was conducted to evaluate the individual and combined cytotoxic effects of DOX and MPC-3100 on MCF-7 and MDA-MB-231 breast cancer cell lines. The effect of two drugs combination was assessed by the Chou and Talalay approach. To further investigate the underlying molecular mechanism responsible for this synergistic effect, the gene expression levels of apoptotic and heat shock proteins (HSP), as well as the protein expression levels, were examined using quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Western Blotting, respectively.

RESULTS

Based on the molecular docking results, it was observed that MPC-3100 specifically binds to the ATP binding pocket of Hsp90, exhibiting an estimated free binding energy of -7.9 kcal/mol. MTT results indicated that both DOX and MPC-3100, as well as their combination, exhibited dose-dependent cytotoxicity. The drug combination showed a synergistic effect on both MCF-7 and MDA-MB-231 cell lines. Finally, the investigated molecular mechanism demonstrated that the combination of DOX and MPC-3100 induced apoptosis in breast cancer cells more efficiently than either drug alone.

CONCLUSIONS

This study showed a possible coordinated mechanism of action between DOX and MPC-3100, pointing to the possibility of a more effective therapeutic strategy for breast cancer therapy.

Co-Delivery of an Innovative Organoselenium Compound and Paclitaxel by pH-Responsive PCL Nanoparticles to Synergistically Overcome Multidrug Resistance in Cancer

In this study, we designed the association of the organoselenium compound 5'-Seleno-(phenyl)-3'-(ferulic-amido)-thymidine (AFAT-Se), a promising innovative nucleoside analogue, with the antitumor drug paclitaxel, in poly(ε-caprolactone) (PCL)-based nanoparticles (NPs). The nanoprecipitation method was used, adding the lysine-based surfactant, 77KS, as a pH-responsive adjuvant. The physicochemical properties presented by the proposed NPs were consistent with expectations. The co-nanoencapsulation of the bioactive compounds maintained the antioxidant activity of the association and evidenced greater antiproliferative activity in the resistant/MDR tumor cell line NCI/ADR-RES, both in the monolayer/two-dimensional (2D) and in the spheroid/three-dimensional (3D) assays. Hemocompatibility studies indicated the safety of the nanoformulation, corroborating the ability to spare non-tumor 3T3 cells and human mononuclear cells of peripheral blood (PBMCs) from cytotoxic effects, indicating its selectivity for the cancerous cells. Furthermore, the synergistic antiproliferative effect was found for both the association of free compounds and the co-encapsulated formulation. These findings highlight the antitumor potential of combining these bioactives, and the proposed nanoformulation as a potentially safe and effective strategy to overcome multidrug resistance in cancer therapy.

Multitargeting Prodrugs that Release Oxaliplatin, Doxorubicin and Gemcitabine are Potent Inhibitors of Tumor Growth and Effective Inducers of Immunogenic Cell Death

A multitargeting prodrug (2) that releases gemcitabine, oxaliplatin, and doxorubicin in their active form in cancer cells is a potent cytotoxic agent with nM IC50s ; it is highly selective to cancer cells with mean selectivity indices to human (136) and murine (320) cancer cells. It effectively induces release of DAMPs (CALR, ATP & HMGB1) in CT26 cells facilitating more efficient phagocytosis by J774 macrophages than the FDA drugs or their co-administration. The viability of CT26 cells co-cultured with J774 macrophages and treated with 2 was reduced by 32 % compared to the non-treated cells, suggesting a synergistic antiproliferative effect between the chemical and immune reactions. 2 inhibited in vivo tumor growth in two murine models (LLC and CT26) better than the FDA drugs or their co-administration with significantly lower body weight loss. Mice inoculated with CT26 cells treated with 2 showed slightly better tumor free survival than doxorubicin.

Synergistic induction of apoptosis in liver cancer cells: exploring the combined potential of doxorubicin and XL-888

Combination therapy has been frequently preferred in treating various types of cancer in recent years. Targeted cancer therapy has also become one of the remarkable treatment modalities. Therefore, the aim of the study to investigate its cytotoxic and apoptotic effects on liver cancer cell lines by combining the classical chemotherapeutic drug doxorubicin (DOX) and a targeted agent, the new generation HSP90 inhibitor XL-888. The molecular docking method was used to predict the binding conformation of XL-888 on the human Hsp90. The single and combined cytotoxic effects of DOX and XL-888 on liver cancer cell lines HepG2 and HUH-7 were determined by MTT assay. The effect of the combined use of two drugs was evaluated using Chou and Talalay method. The levels of apoptotic genes and heat shock proteins gene and protein expression levels were investigated by quantitative real-time polymerase chain reaction and western blotting, respectively. Molecular docking results showed that XL-888 selectively binds to the ATP binding pocket of HSP90 with an estimated free binding energy of - 7.8 kcal/mol. DOX and XL-888 and their combination showed dose-dependent cytotoxic effect. The combination of drugs showed a synergistic effect on both cell lines. The results revealed that the combination of DOX and XL-888 potently induced apoptosis in liver cancer cell lines rather than using drugs alone. The combined treatment of DOX and XL-888 demonstrated synergistic cytotoxic and apoptotic effects on liver cancer cell lines, presenting a promising approach for combination therapy in liver cancer.

Triplex metallohelices have enantiomer-dependent mechanisms of action in colon cancer cells

Self-assembled enantiomers of an asymmetric di-iron metallohelix differ in their antiproliferative activities against HCT116 colon cancer cells such that the compound with Λ-helicity at the metals becomes more potent than the Δ compound with increasing exposure time. From concentration- and temperature-dependent ⁵⁷Fe isotopic labelling studies of cellular accumulation we postulate that while the more potent Λ enantiomer undergoes carrier-mediated efflux, for Δ the process is principally equilibrative. Cell fractionation studies demonstrate that both enantiomers localise in a similar fashion; compound is observed mostly within the cytoskeleton and/or genomic DNA, with significant amounts also found in the nucleus and membrane, but with negligible concentration in the cytosol. Cell cycle analyses using flow cytometry reveal that the Δ enantiomer induces mild arrest in the G₁ phase, while Λ causes a very large dose-dependent increase in the G₂/M population at a concentration significantly below the relevant IC₅₀. Correspondingly, G₂-M checkpoint failure as a result of Λ-metallohelix binding to DNA is shown to be feasible by linear dichroism studies, which indicate, in contrast to the Δ compound, a quite specific mode of binding, probably in the major groove. Further, spindle assembly checkpoint (SAC) failure, which could also be responsible for the observed G₂/M arrest, is established as a feasible mechanism for the Λ helix via drug combination (synergy) studies and the discovery of tubulin and actin inhibition. Here, while the Λ compound stabilizes F-actin and induces a distinct change in tubulin architecture of HCT116 cells, Δ promotes depolymerization and more subtle changes in microtubule and actin networks.

Synergistic Encapsulation of Paclitaxel and Sorafenib by Methoxy Poly(Ethylene Glycol)-b-Poly(Caprolactone) Polymeric Micelles for Ovarian Cancer Therapy

Ovarian cancer has a high mortality rate due to difficult detection at an early stage. It is necessary to develop a novel anticancer treatment that demonstrates improved efficacy while reducing toxicity. Here, using the freeze-drying method, micelles encapsulating paclitaxel (PTX) and sorafenib (SRF) with various polymers were prepared, and the optimal polymer (mPEG-b-PCL) was selected by measuring drug loading (%), encapsulation efficiency (%), particle size, polydispersity index, and zeta potential. The final formulation was selected based on a molar ratio (PTX:SRF = 1:2.3) with synergistic effects on two ovarian cancer cell lines (SKOV3-red-fluc, HeyA8). In the in vitro release assay, PTX/SRF micelles showed a slower release than PTX and SRF single micelles. In pharmacokinetic evaluation, PTX/SRF micelles showed improved bioavailability compared to PTX/SRF solution. In in vivo toxicity assays, no significant differences were observed in body weight between the micellar formulation and the control group. The anticancer effect of PTX/SRF combination therapy was improved compared to the use of a single drug. In the xenografted BALB/c mouse model, the tumor growth inhibition rate of PTX/SRF micelles was 90.44%. Accordingly, PTX/SRF micelles showed improved anticancer effects compared to single-drug therapy in ovarian cancer (SKOV3-red-fluc).

DBDPE and ZnO NPs synergistically induce neurotoxicity of SK-N-SH cells and activate mitochondrial apoptosis signaling pathway and Nrf2-mediated antioxidant pathway

Decabromodiphenyl ethane (DBDPE), a new brominated flame retardant, could negatively affect neurobehavior and pose health risks to humans. Humans are also exposed to widely used nanomaterials. This study investigated the combined toxic effects and action types of DBDPE and Zinc oxide nanoparticles (ZnO NPs) on human neuroblastoma SK-N-SH cells and the toxicity mechanisms. DBDPE inhibited the viability of SK-N-SH cells by 21.87% at 25 mg/L. ZnO NPs synergistically exacerbated the toxic effects of DBDPE. DBDPE and ZnO NPs caused excessive ROS production and inhibition of antioxidant enzyme (SOD and GSH) activity in cells, thus causing oxidative cellular damage. Moreover, DBDPE and ZnO NPs caused apoptosis by disrupting mitochondrial kinetic homeostasis, reducing mitochondrial membrane potential (MMP), increasing cytochrome C release and regulating Bax/Bcl-2 and Caspase-3 mRNA and protein expression. DBDPE and ZnO NPs increased the mRNA expression of nuclear factor erythroid 2- related factor (Nrf2) and its downstream genes. The molecular mechanisms revealed that oxidative stress, apoptosis and mitochondrial dysfunction were the critical factors in combined cytotoxicity. The bioinformatics analysis further indicated that co-exposure affected Nrf2 activation, apoptotic factors expression and mitochondrial fusion. The findings enrich the risk perception of neurotoxicity caused by DBDPE and ZnO NPs.

Discovery of potential natural dihydroorotate dehydrogenase inhibitors and their synergism with brequinar via integrated molecular docking, dynamic simulations and in vitro approach

The critical function of dihydroorotate dehydrogenase (DHODH) in pyrimidine synthesis attracted a great interest throughout beyond decades. Inhibitors of human DHODH (hDHODH) have validated efficacy for remedy of many immunological diseases. Brequinar and leflunomide are examples of such compounds. However, most of such immunosuppressive medications suffer from a lot of side effects and accompanied by adverse metabolic disturbances and toxicities. So that, immunomodulation utilizing natural products received the attention of many researchers. In this study, computer-aided molecular docking, molecular dynamic (MD) simulations and biochemical testing were utilized to find new pharmacologically active chemical entities from natural sources to combat immunosuppressive diseases. More specifically, Glide docking was used for a structure-based virtual screening of in-house 3D database of compounds retrieved from some traditionally known immunomodulatory plants surveyed from literature. The top five scored plants were found to be Zingiber officinale, Curcuma longa, Glycyrrhiza glabra, Allium sativum and Olea europaea. In vitro hDHODH inhibitory assays illustrated the ability of Allium sativum and silymarin standard hits; specifically, silibinin, to significantly inhibit the hDHODH enzyme. Molecular docking and MD simulations revealed a strong binding of the discovered hits within the active site. Following that, the most promising hits were tested separately with brequinar in a fixed-ratio combination setting to assess their combined effects on hDHODH catalytic inhibition. The binary combination of silibinin and brequinar revealed that in this combination, brequinar could be utilized at a dose 9.33-fold less when compared to its single-use to produce 99% inhibition for hDHODH enzyme. These findings confirmed that this binary mixture is an excellent combination providing better therapeutic effects and lower side effects.

In vitro antiviral effects of GS-441524 and itraconazole combination against feline infectious peritonitis virus

Feline infectious peritonitis virus (FIPV: virulent feline coronavirus) causes a fatal disease called feline infectious peritonitis (FIP) in wild and domestic cat species. Recent studies identified several antiviral drugs that are effective against FIPV. Drug combination is one of the important strategies in the development of novel treatments for viral infections. GS-441524, a nucleoside analog, and itraconazole, a triazole antifungal drug, have been reported that have antiviral effect against FIPV. This study aims to investigate whether the combination of GS-441524 and itraconazole has synergic antiviral effect against FIPV. The antiviral effect was measured by plaque reduction assay using felis catus whole fatus-4 cell. The plaque reduction of GS-441524 against type I FIPVs increased as the concentration of itraconazole increased. The similar result was obtained for type II FIPV. In addition, the calculated combination index (CI) demonstrated that there was a strong synergy between GS-441524 and itraconazole. It is concluded that the combination of GS-441524 and itraconazole may enhance the individual effect of each drug against replication of type I FIPVs and may contribute to development more effective treatment strategy for FIP.

Overcoming MDR by Associating Doxorubicin and pH-Sensitive PLGA Nanoparticles Containing a Novel Organoselenium Compound-An In Vitro Study

In this study, we developed PLGA nanoparticles (NPs) as an effective carrier for 5'-Se-(phenyl)-3-(amino)-thymidine (ACAT-Se), an organoselenium compound, nucleoside analogue that showed promising antitumor activity in vitro. The PLGA NPs were prepared by the nanoprecipitation method and modified with a pH-responsive lysine-based surfactant (77KL). The ACAT-Se-PLGA-77KL-NPs presented nanometric size (around 120 nm), polydispersity index values < 0.20 and negative zeta potential values. The nanoencapsulation of ACAT-Se increased its antioxidant (DPPH and ABTS assays) and antitumor activity in MCF-7 tumor cells. Hemolysis study indicated that ACAT-Se-PLGA-77KL-NPs are hemocompatible and that 77KL provided a pH-sensitive membranolytic behavior to the NPs. The NPs did not induce cytotoxic effects on the nontumor cell line 3T3, suggesting its selectivity for the tumor cells. Moreover, the in vitro antiproliferative activity of NPs was evaluated in association with the antitumor drug doxorubicin. This combination result in synergistic effect in sensitive (MCF-7) and resistant (NCI/ADR-RES) tumor cells, being especially able to successfully sensitize the MDR cells. The obtained results suggested that the proposed ACAT-Se-loaded NPs are a promising delivery system for cancer therapy, especially associated with doxorubicin.

A Ferrocene-Functionalized Covalent Organic Framework for Enhancing Chemodynamic Therapy via Redox Dyshomeostasis

Chemodynamic therapy (CDT), which induces cell death by decomposing high levels of H₂ O₂ in tumor cells into highly toxic ·OH, is recognized as a promising antineoplastic approach. However, current CDT approaches are often restricted by the highly controlled and upregulated cellular antioxidant defense. To enhance ·OH-induced cellular damage by CDT, a covalent organic framework (COF)-based, ferrocene (Fc)- and glutathione peroxidase 4 (GPX4) inhibitor-loaded nanodrug, RSL3@COF-Fc (2b), is fabricated. The obtained 2b not only promotes in situ Fenton-like reactions to trigger ·OH production in cells, but also attenuates the repair mechanisms under oxidative stress via irreversible covalent GPX4 inhibition. As a result, these two approaches synergistically result in massive lipid peroxide accumulation, subsequent cell damage, and ultimately ferroptosis, while not being limited by intracellular glutathione. It is believed that this research provides a paradigm for enhancing reactive oxygen species-mediated oncotherapy through redox dyshomeostasis and may provide new insights for developing COF-based nanomedicine.

Effect of Piperine in Combination with Gamma Radiation on A549 Cells

Background Lung cancer is a major constrain that increases mortality globally. Radiotherapy is one of the treatment modalities against lung cancer. A high dose of targeted radiation is required to achieve the treatment efficacy of cell killing. After radiotherapy, eventual tumor progression and therapy resistance are still a consequence of patient who undertakes nonsurgical radiation therapy. Piperine, a plant alkaloid, has been known to enhance the action of the anticancer drugs in various drug-resistant cancer cells. The aim of the current in vitro study was to study the effect of piperine on radiosensitizing property against A549 cells.

Methods In vitro radiosensitizing activity of piperine was elucidated on A549 cells using MTT (3-(4, 5-dimethylthiazol-2-yl)-25-diphenyltetrazolium bromide) assay. CompuSyn analysis was used to compute the combination index values to analyze the combinatory effect of piperine and radiation

Results and Conclusion We observed that piperine increased tumor cell killing in combination with the γ-radiation in vitro. However, further studies are warranted to understand the molecular mechanism of the radiosensitizing action of piperine.

Poly-(Lactic-co-Glycolic) Acid Nanoparticles for Synergistic Delivery of Epirubicin and Paclitaxel to Human Lung Cancer Cells

Combination therapy using chemically distinct drugs has appeared as one of the promising strategies to improve anticancer treatment efficiency. In the present investigation, poly-(lactic-co-glycolic) acid (PLGA) nanoparticles electrostatically conjugated with polyethylenimine (PEI)-based co-delivery system for epirubicin and paclitaxel (PLGA-PEI-EPI-PTX NPs) has been developed. The PLGA-PEI-EPI-PTX NPs exhibited a monodispersed size distribution with an average size of 240.93 ± 12.70 nm as measured through DLS and 70.8-145 nm using AFM. The zeta potential of 41.95 ± 0.65 mV from -17.45 ± 2.15 mV further confirmed the colloidal stability and PEI modification on PLGA nanoparticles. Encapsulation and loading efficiency along with in vitro release of drug for nanoparticles were done spectrophotometrically. The FTIR analysis of PLGA-PEI-EPI-PTX NPs revealed the involvement of amide moiety between polymer PLGA and PEI. The effect of nanoparticles on the cell migration was also corroborated through wound healing assay. The MTT assay demonstrated that PLGA-PEI-EPI-PTX NPs exhibited considerable anticancer potential as compared to the naïve drugs. Further, p53 protein expression analysed through western blot showed enhanced expression. This study suggests that combination therapy using PLGA-PEI-EPI-PTX NPs represent a potential approach and could offer clinical benefits in the future for lung cancer patients.

Mixture effects of chemicals: The difficulty to choose appropriate mathematical models for appropriate conclusions

Many different approaches have been proposed to evaluate and predict mixture effects. From a regulatory perspective, several guidance documents have been recently published and provide a strategy for mixture risk assessment based on valuable frameworks to investigate potential synergistic effects. However, some methodological aspects, e.g. for considering mathematical models, are not sufficiently defined. Therefore, the aim of this study was to examine the usefulness of five main mathematical models for mixture effect interpretation: theoretical additivity (TA), concentration addition (CA), independent action (IA), Chou-Talalay (CT), and a benchmark dose approach (BMD) were tested using a fictional data set depicting scenarios of additivity, synergism and antagonism. The synergism and antagonism scenarios were split in x-axis and y-axis synergism/antagonism, meaning a shift of the curve on x-axis or y-axis. The BMD approach was the only model which showed a perfect correspondence for dose addition. Regarding synergism and antagonism, all approaches correspond well for the x-axis synergism and antagonism with only few exceptions. In contrast, some limitations were observed in the particular scenarios of y-axis synergism and antagonism. Therefore our results show that each model has advantages and disadvantages, and that therefore no single model appears the best one for all kinds of application. We would recommend instead the parallel use of different models to increase confidence in the result of mixture effect evaluation.

Synergistic lethal mutagenesis of hepatitis C virus

Lethal mutagenesis is an antiviral approach that consists in extinguishing a virus by an excess of mutations acquired during replication in the presence of a mutagenic agent, often a nucleotide analogue. One of its advantages is its broad spectrum nature that renders the strategy potentially effective against emergent RNA viral infections. Here we describe synergistic lethal mutagenesis of hepatitis C virus (HCV) by a combination of favipiravir (T-705) and ribavirin. Synergy has been documented over a broad range of analogue concentrations using the Chou-Talalay method as implemented in the CompuSyn graphics, with average dose reduction index (DRI) above 1 (68.02±101.6 for favipiravir, and 5.83±6.07 for ribavirin), and average combination indices (CI) below 1 (0.52±0.28). Furthermore, analogue concentrations that individually did not extinguish high fitness HCV in ten serial infections, when used in combination they extinguished high fitness HCV in one to two passages. Although both analogues display a preference for G→A and C→U transitions, deep sequencing analysis of mutant spectra indicated a different preference of the two analogues for the mutation sites, thus unveiling a new possible synergy mechanism in lethal mutagenesis. Prospects of synergy among mutagenic nucleotides as a strategy to confront emerging viral infections are discussed.

The antitrypanosomal diarylamidines, diminazene and pentamidine, show anthelmintic activity against Haemonchus contortus in vitro

Parasitic nematodes pose a major threat to livestock production worldwide. The blood-feeding parasite Haemonchus contortus is a key small-ruminant pathogen that causes anaemia, and thereby seriously impacts animal health and production. Control of this parasite relies largely upon broad-spectrum anthelmintics, but new drugs are urgently needed to combat the threat of widespread multidrug resistance. Repurposing drugs can accelerate the development pipeline by reducing costs and risks, and can be an effective way of quickly bringing new antiparasitic drugs to market. Diarylamidine compounds such as pentamidine and diminazene have been employed in the treatment of trypanosomiasis and leishmaniasis in both human and veterinary settings, but their activity against parasitic worms has not yet been reported. We screened a small panel of diarylamidine compounds against H. contortus to assess their potential to be repurposed as anthelmintic drugs. Pentamidine and diminazene inhibited H. contortus larval development at low micromolar concentrations (IC₅₀ 4.9 μM and 16.1 μM, respectively, in a drug-susceptible isolate) with no existing cross-resistance in two multidrug resistant isolates and a monepantel-resistant isolate. Combinations of pentamidine with commercial anthelmintics showed additive activity, with no significant synergism detected. Pentamidine and diminazene showed different life-stage patterns of activity; both were active against early stage larvae in development assays, but only diminazene was active against the infective L3 stage in migration assays. This suggests some differences in uptake of the two drugs across the nematode cuticle, or differences in the nature and expression patterns of their molecular targets. As pentamidine and diminazene have been reported to be potent inhibitors of mammalian acid-sensing ion channels (ASIC), we tested the activity of known ASIC inhibitors against H. contortus to probe whether these channels may represent potential anthelmintic targets in nematodes. Remarkably, the spider-venom peptide Hi1a, a potent inhibitor of ASIC1a, inhibited H. contortus larval development with an IC₅₀ of 22.9 ± 1.9 μM. This study highlights the potential use of diarylamidines as anthelmintics, although their activity needs to be confirmed in vivo. In addition, our demonstration that ASIC inhibitors have anthelmintic activity raises the possibility that this family of ion channels may represent a novel anthelmintic target.

Adrenomedullin blockade suppresses sunitinib-resistant renal cell carcinoma growth by targeting the ERK/MAPK pathway

PURPOSE

To evaluate the mechanisms underlying sunitinib resistance in RCC and to identify targets that may be used to overcome this resistance.

RESULTS

Reanalysis of transcriptome microarray datasets (GSE64052 and GSE76068) showed that adrenomedullin expression was increased in sunitinib-resistant tumors. And adrenomedullin expression was increased in sunitinib-resistant tumor xenografts, accompanied by upregulation of phospho-ERK levels. However, blocking adrenomedullin inhibited sunitinib-resistant tumor growth. Treatment of RCC cells with sunitinib and ADM22-52 was superior to monotherapy with either agent. Additionally, adrenomedullin upregulated cAMP and activated the ERK/MAPK pathway, promoting cell proliferation, while knockdown of adrenomedullin inhibited RCC cell growth and invasion in vitro.

MATERIALS AND METHODS

We searched the Gene Expression Omnibus (GEO) database to find data regarding sunitinib-resistant RCC. These data were subsequently reanalyzed to identify targets that contribute to sunitinib resistance, and adrenomedullin upregulation was found to mediate sunitinib resistance in RCC. Then, we created an RCC mouse xenograft model. Mice were treated with sunitinib, an adrenomedullin receptor antagonist (ADM22-52), a MEK inhibitor (PD98059) and different combinations of these three drugs to investigate their effects on tumor growth. RCC cells (786-0) were cultured in vitro and treated with an ADM22-52 or PD98059 to determine whether adrenomedullin activates the ERK/MAPK pathway. Adrenomedullin was knocked down in 786-0 cells via siRNA, and the effects of this knockdown on cell were subsequently investigated.

CONCLUSIONS

Adrenomedullin plays an important role in RCC resistance to sunitinib treatment. The combination of sunitinib and an adrenomedullin receptor antagonist may result in better outcomes in advanced RCC patients.

Onionin A inhibits ovarian cancer progression by suppressing cancer cell proliferation and the protumour function of macrophages

It is well known that tumour-associated macrophages (TAMs) play an important role in tumour development by modulating the tumour microenvironment, and targeting of protumour activation or the M2 polarization of TAMs is expected to be an effective therapy for cancer patients. We previously demonstrated that onionin A (ONA), a natural low molecular weight compound isolated from onions, has an inhibitory effect on M2 macrophage polarization. In the present study, we investigated whether ONA had a therapeutic anti-ovarian cancer effect using in vitro and in vivo studies. We found that ONA reduced the extent of ovarian cancer cell proliferation induced by co-culture with human macrophages. In addition, we also found that ONA directly suppressed cancer cell proliferation. A combinatorial effect with ONA and anti-cancer drugs was also observed. The activation of signal transducer and activator of transcription 3 (STAT3), which is involved in cell proliferation and chemo-resistance, was significantly abrogated by ONA in ovarian cancer cells. Furthermore, the administration of ONA suppressed cancer progression and prolonged the survival time in a murine ovarian cancer model under single and combined treatment conditions. Thus, ONA is considered useful for the additional treatment of patients with ovarian cancer owing to its suppression of the protumour activation of TAMs and direct cytotoxicity against cancer cells.

Combined Effects of Lipophilic Phycotoxins (Okadaic Acid, Azapsiracid-1 and Yessotoxin) on Human Intestinal Cells Models

Phycotoxins are monitored in seafood because they can cause food poisonings in humans. Phycotoxins do not only occur singly but also as mixtures in shellfish. The aim of this study was to evaluate the in vitro toxic interactions of binary combinations of three lipophilic phycotoxins commonly found in Europe (okadaic acid (OA), yessotoxin (YTX) and azaspiracid-1 (AZA-1)) using the neutral red uptake assay on two human intestinal cell models, Caco-2 and the human intestinal epithelial crypt-like cells (HIEC). Based on the cytotoxicity of individual toxins, we studied the interactions between toxins in binary mixtures using the combination index-isobologram equation, a method widely used in pharmacology to study drug interactions. This method quantitatively classifies interactions between toxins in mixtures as synergistic, additive or antagonistic. AZA-1/OA, and YTX/OA mixtures showed increasing antagonism with increasing toxin concentrations. In contrast, the AZA-1/YTX mixture showed increasing synergism with increasing concentrations, especially for mixtures with high YTX concentrations. These results highlight the hazard potency of AZA-1/YTX mixtures with regard to seafood intoxication.

Co-delivery of protein and small molecule therapeutics using nanoparticle-stabilized nanocapsules

Combination therapy employing proteins and small molecules provides access to synergistic treatment strategies. Co-delivery of these two payloads is challenging due to the divergent physicochemical properties of small molecule and protein cargos. Nanoparticle-stabilized nanocapsules (NPSCs) are promising for combination treatment strategies since they have the potential to deliver small molecule drugs and proteins simultaneously into the cytosol. In this study, we loaded paclitaxel into the hydrophobic core of the NPSC and self-assembled caspase-3 and nanoparticles on the capsule surface. The resulting combination NPSCs showed higher cytotoxicity than either of the single agent NPSCs, with synergistic action established using combination index values.