LL37-Derived Fragments Improve the Antibacterial Potential of Penicillin G and Ampicillin against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infections are a severe threat to public health. Antimicrobial peptides (AMPs) are novel and potential antimicrobials with specific antibacterial mechanisms. Our aim was to study the potential of LL37, FK16, and FK13 to enhance the anti-MRSA activity of antibiotics in vitro, particularly penicillin G and ampicillin. Our results showed that FK16 and FK13 have more synergistic inhibitory effects to MRSA strains when combined with penicillin G and ampicillin. In addition, AMPs exhibited strong membrane permeabilizing properties, and membrane permeabilizing effects can provide a possible explanation for the improved antibacterial effects of antibiotics, since permeabilizing AMPs have the potential to increase the access of antibiotics. To further study the electrostatic interactions among cationic AMPs with negatively charged bacteria, we measured the zeta potentials of three MRSA strains and also neutralized three MRSA strains with the addition of cationic AMPs. Further, we demonstrated the connection between membrane permeabilization and zeta potential neutralization. Finally, we treated MRSA strains with AMPs and characterized the MICs of penicillin G and ampicillin. FK16 was the most promising AMP among the three AMPs, since exposure to FK16 decreased the MICs of both penicillin G and ampicillin for all MRSA strains and also demonstrated more synergistic combinations when combined with antibiotics. AMP exposure and subsequent membrane permeabilization provide a possible pathway to re-sensitize drug-resistant bacteria to traditional antibiotics. Re-sensitization may help preserve the effectiveness of traditional antibiotics, thus providing a potential new strategy for fighting MRSA infections.

IFNα primes cancer cells for Fusicoccin-induced cell death via 14-3-3 PPI stabilization

The natural product family of the fusicoccanes (FCs) has been shown to display anti-cancer activity, especially when combined with established therapeutic agents. FCs stabilize 14-3-3 protein-protein interactions (PPIs). Here, we tested combinations of a small library of FCs with interferon α (IFNα) on different cancer cell lines and report a proteomics approach to identify the specific 14-3-3 PPIs that are induced by IFNα and stabilized by FCs in OVCAR-3 cells. Among the identified 14-3-3 target proteins are THEMIS2, receptor interacting protein kinase 2 (RIPK2), EIF2AK2, and several members of the LDB1 complex. Biophysical and structural biology studies confirm these 14-3-3 PPIs as physical targets of FC stabilization, and transcriptome as well as pathway analyses suggest possible explanations for the observed synergistic effect of IFNα/FC treatment on cancer cells. This study elucidates the polypharmacological effects of FCs in cancer cells and identifies potential targets from the vast interactome of 14-3-3s for therapeutic intervention in oncology.

Huperzia serrata Extract 'NSP01' With Neuroprotective Effects-Potential Synergies of Huperzine A and Polyphenols

Huperzia serrata (Thunb.) Trevis is widely used in traditional asiatic medicine to treat many central disorders including, schizophrenia, cognitive dysfunction, and dementia. The major alkaloid, Huperzine A (HA), of H. serrata is a well-known competitive reversible inhibitor of acetylcholinesterase (AChE) with neuroprotective effects. Inspired by the tradition, we developed a green one-step method using microwave assisted extraction to generate an extract of H. serrata, called NSP01. This green extract conserves original neuropharmacological activity and chemical profile of traditional extract. The neuroprotective activity of NSP01 is based on a precise combination of three major constituents: HA and two phenolic acids, caffeic acid (CA) and ferulic acid (FA). We show that CA and FA potentiate HA-mediated neuroprotective activity. Importantly, the combination of HA with CA and FA does not potentiate the AChE inhibitory property of HA which is responsible for its adverse side effects. Collectively, these experimental findings demonstrated that NSP01, is a very promising plant extract for the prevention of Alzheimer's disease and memory deficits.

The Enhanced Efficacy of Intracellular Delivery of Doxorubicin/C6-Ceramide Combination Mediated by the F3 Peptide/Nucleolin System Is Supported by the Downregulation of the PI3K/Akt Pathway

Simple Summary

Targeted nanomedicine-based approaches that aim at the simultaneous delivery of synergistic drug combinations to multiple cellular populations are of high relevance for tackling heterogeneity on solid tumors. Considering that cancer stem cells (CSC) may originate from non-stem cancer cells, single-drug regimens targeting only one of these cell populations could enable tumors to evade treatments. As such, the identification of a common marker, such as nucleolin, might result in a therapeutic advantage. The results herein generated suggested a transversal role of nucleolin in the internalization of F3 peptide-targeted pegylated pH-sensitive liposomes into bulk ovarian cancer cells, including putative CSC-enriched ovarian cells. The intracellular delivery of a drug combination such as the one tested herein was relevant in the context of cell lines with higher intrinsic resistances to doxorubicin. The enhanced efficacy of the F3 peptide-targeted liposomal combination of doxorubicin/C6-ceramide was supported by the downregulation of the Akt pathway, within a specific range of basal level of expression.

Abstract

Targeting multiple cellular populations is of high therapeutic relevance for the tackling of solid tumors heterogeneity. Herein, the ability of pegylated and pH-sensitive liposomes, functionalized with the nucleolin-binding F3 peptide and containing doxorubicin (DXR)/C6-ceramide synergistic combination, to target, in vitro, ovarian cancer, including ovarian cancer stem cells (CSC), was assessed. The underlying molecular mechanism of action of the nucleolin-mediated intracellular delivery of C6-ceramide to cancer cells was also explored. The assessment of overexpression of surface nucleolin expression by flow cytometry was critical to dissipate differences identified by Western blot in membrane/cytoplasm of SKOV-3, OVCAR-3 and TOV-112D ovarian cancer cell lines. The former was in line with the significant extent of uptake into (bulk) ovarian cancer cells, relative to non-targeted and non-specific counterparts. This pattern of uptake was recapitulated with putative CSC-enriched ovarian SKOV-3 and OVCAR-3 sub-population (EpCAM^high/CD44^high). Co-encapsulation of DXR:C6-ceramide into F3 peptide-targeted liposomes improved cytotoxic activity relative to liposomes containing DXR alone, in an extent that depended on the intrinsic resistance to DXR and on the incubation time. The enhanced cytotoxicity of the targeted combination was mechanistically supported by the downregulation of PI3K/Akt pathway by C6-ceramide, only among the nucleolin-overexpressing cancer cells presenting a basal p-Akt/total Akt ratio lower than 1.

Structural Bases for the Synergistic Inhibition of Human Thymidylate Synthase and Ovarian Cancer Cell Growth by Drug Combinations

Simple Summary

Drug combinations may help overcome drug resistance, a relevant cause of failure of ovarian cancer therapy. However, designing successful combinations requires a lengthy preclinical validation process. We have analyzed combinations of 5-fluorouracil and raltitrexed, two anticancer drugs that target thymidylate synthase, a key enzyme for the nucleotide synthesis. We have observed administration sequence specific and synergistic combined effects of the two drugs against cisplatin sensitive and resistant ovarian cancer cells. However, the focus of this work was to show that a high stability of the complex of the enzyme with the two drugs, as highlighted by X-ray crystallography, and synergistic inhibition of the enzyme represent indicators, if not prerequisites, for this drug combination to be synergistically active against sensitive and resistant ovarian cancer cells. We thus propose that structural and mechanistic information acquired during the preclinical research can help predict a successful therapeutic application of a drug combination.

Abstract

Combining drugs represent an approach to efficiently prevent and overcome drug resistance and to reduce toxicity; yet it is a highly challenging task, particularly if combinations of inhibitors of the same enzyme target are considered. To show that crystallographic and inhibition kinetic information can provide indicators of cancer cell growth inhibition by combinations of two anti-human thymidylate synthase (hTS) drugs, we obtained the X-ray crystal structure of the hTS:raltitrexed:5-fluorodeoxyuridine monophosphate (FdUMP) complex. Its analysis showed a ternary complex with both molecules strongly bound inside the enzyme catalytic cavity. The synergistic inhibition of hTS and its mechanistic rationale were consistent with the structural analysis. When administered in combination to A2780 and A2780/CP ovarian cancer cells, the two drugs inhibited ovarian cancer cell growth additively/synergistically. Together, these results support the idea that X-ray crystallography can provide structural indicators for designing combinations of hTS (or any other target)-directed drugs to accelerate preclinical research for therapeutic application.

Combination of Ginsenosides Rb2 and Rg3 Promotes Angiogenic Phenotype of Human Endothelial Cells via PI3K/Akt and MAPK/ERK Pathways

Shexiang Baoxin Pill (SBP) is an oral formulation of Chinese materia medica for the treatment of angina pectoris. It displays pleiotropic roles in protecting the cardiovascular system. However, the mode of action of SBP in promoting angiogenesis, and in particular the synergy between its constituents is currently not fully understood. The combination of ginsenosides Rb2 and Rg3 were studied in human umbilical vein endothelial cells (HUVECs) for their proangiogenic effects. To understand the mode of action of the combination in more mechanistic detail, RNA-Seq analysis was conducted, and differentially expressed genes (DEGs), pathway analysis and Weighted Gene Correlation Network Analysis (WGCNA) were applied to further identify important genes that a play pivotal role in the combination treatment. The effects of pathway-specific inhibitors were observed to provide further support for the hypothesized mode of action of the combination. Ginsenosides Rb2 and Rg3 synergistically promoted HUVEC proliferation and tube formation under defined culture conditions. Also, the combination of Rb2/Rg3 rescued cells from homocysteine-induced damage. mRNA expression of CXCL8, CYR61, FGF16 and FGFRL1 was significantly elevated by the Rb2/Rg3 treatment, and representative signaling pathways induced by these genes were found. The increase of protein levels of phosphorylated-Akt and ERK42/44 by the Rb2/Rg3 combination supports the notion that it promotes endothelial cell proliferation via the PI3K/Akt and MAPK/ERK signaling pathways. The present study provides the hypothesis that SBP, via ginsenosides Rb2 and Rg3, involves the CXCR1/2 CXCL8 (IL8)-mediated PI3K/Akt and MAPK/ERK signaling pathways in achieving its proangiogenic effects.

Bio-preservation of chocolate mousse with free and immobilized cells of Lactobacillus plantarum D2 and lemon (Citrus lemon L.) or grapefruit (Citrus paradisi L.) zest essential oils

BACKGROUND

The bio-preservation of food products using various natural ingredients and metabolites from various types of beneficial microorganisms released during targeted fermentation is a method that simultaneously has a preservative effect on the food product and provides a model of its composition in order to ensure its functional and health properties. This double effect can be achieved by incorporating ingredients with proven preservative and functional effects into the food product, such as essential oils from various plant species and probiotic bacteria. The aim of the present research was to study the synergistic effect of selected probiotic lactic acid bacteria (LAB) and essential oils with high antimicrobial activity against pathogenic and spoilage microorganisms for the bio-preservation of chocolate mousse food emulsion.

METHODS

The susceptibility of the selected probiotic strain Lactobacillus plantarum D2 to different concentrations of the selected lemon or grapefruit essential oil was examined using the disc-diffusion method. Nine chocolate mousse variants were prepared with the inclusion of free or immobilized cells of the probiotic strain L. plantarum D2 and/or lemon or grapefruit zest essential oils. The chocolate mousse variants were stored for 20 days in refrigerated conditions, and changes in the concentration of viable lactobacilli cells, the pH and the microbiological purity were monitored in accordance with standard requirements by taking samples on the 0th, 5th, 10th, 15th, and 20th days of storage. An organoleptic evaluation of the chocolate variants was performed on the 0th day.

RESULTS

Concentrations of up to 1% lemon or grapefruit essential oil did not affect the growth of the probiotic strain L. plantarum D2, which revealed opportunities for their joint application for the bio-preservation of food emulsions. The obtained chocolate mousse variants were characterized by preserved organoleptic characteristics and microbiological safety. Free or immobilized probiotic L. plantarum D2 cells applied alone or in combination with lemon or grapefruit essential oils provided bio-preservation of the food emulsions, maintaining a high concentration of viable cells (106-107 cfu/g) during storage under refrigerated conditions for 20 days.

CONCLUSIONS

The combined application of free or immobilized probiotic LAB and lemon or grapefruit essential oils resulted in better bio-preservation results than in the use of probiotic LAB or essential oils alone, thus suggesting a synergistic effect between the two bio-preservative agents. Moreover, the obtained chocolate mousse emulsions can be classified as functional foods and the chocolate mousse food matrix can successfully be used as a vehicle for delivery of probiotic LAB to a wide range of food consumers. The obtained results and the developed successful bio-preservation strategy for the production of chocolate mousse food emulsions would provide grounds for the future selection of other probiotic lactobacilli strains, essential oils and synergistic combinations of them for the development of successful bio-preservation strategies for other types of food and beverage products.

H-RACS: a handy tool to rank anti-cancer synergistic drugs

Though promising, identifying synergistic combinations from a large pool of candidate drugs remains challenging for cancer treatment. Due to unclear mechanism and limited confirmed cases, only a few computational algorithms are able to predict drug synergy. Yet they normally require the drug-cell treatment results as an essential input, thus exclude the possibility to pre-screen those unexplored drugs without cell treatment profiling. Based on the largest dataset of 33,574 combinational scenarios, we proposed a handy webserver, H-RACS, to overcome the above problems. Being loaded with chemical structures and target information, H-RACS can recommend potential synergistic pairs between candidate drugs on 928 cell lines of 24 prevalent cancer types. A high model performance was achieved with AUC of 0.89 on independent combinational scenarios. On the second independent validation of DREAM dataset, H-RACS obtained precision of 67% among its top 5% ranking list. When being tested on new combinations and new cell lines, H-RACS showed strong extendibility with AUC of 0.84 and 0.81 respectively. As the first online server freely accessible at http://www.badd-cao.net/h-racs, H-RACS may promote the pre-screening of synergistic combinations for new chemical drugs on unexplored cancers.

Effect of a New Synergistic Combination of Low Doses of Acetylsalicylic Acid, Caffeine, Acetaminophen, and Chlorpheniramine in Acute Low Back Pain

The present paper continues a more complex research related to the increased synergism in terms of both anti-inflammatory and analgesic effect obtained by the addition of chlorpheniramine (CLF) to the common acetylsalicylic acid (ASA), acetaminophen (PAR), and caffeine (CAF) combination. This synergistic effect was previously highlighted both in vitro in rat models and in vivo in the treatment of migraine. The aim of the research was to further evaluate the analgesic effect of a synergistic low-dose ASA-PAR-CAF-CLF combination in the treatment of low back pain, in a parallel, multiple-dose, double-blind, active controlled clinical trial. A number of 89 patients with low back pain of at least moderate intensity were randomly assigned to receive Algopirin^® (ALG), a combinational product containing 125 mg ASA, 75 mg PAR, 15 mg CAF, and 2 mg CLF, or PAR 500 mg, a drug recognized by American Pain Society as "safe and effective" in the treatment of low back pain. One tablet of the assigned product was administered three times a day for seven consecutive days. The patients evaluated their pain level using a Visual Analog Scale prior to administration, and at 1, 2, 4, and 6 h after the morning dose. Time course of effect was similar in structure and size for both treatments. Pain relief appeared rapidly and steadily increased over 4 h after drug administration. Differential pain curves of ALG and PAR were very similar and comparable with the previously determined ALG analgesia pattern in migraine. Differences between the daily mean pain scores were not statistically significant for the two treatments. Similar results were obtained for the Sum of Pain Intensity Differences (SPID) for 0-4 h and 0-6 h intervals as well as for the time course of the proportion of patients with at least 30% and at least 50% pain relief. In conclusion, in spite of very small doses of active components, ALG proved equally effective to the standard low back pain treatment and therefore a viable therapeutic alternative, mainly for patients with gastrointestinal and hepatic sensitivity. Trial Registration: www.ClinicalTrials.gov, identifier EudraCT No.: 2015-002314-74.

Searching Synergistic Dose Combinations for Anticancer Drugs

Recent development has enabled synergistic drugs in treating a wide range of cancers. Being highly context-dependent, however, identification of successful ones often requires screening of combinational dose on different testing platforms in order to gain the best anticancer effects. To facilitate the development of effective computational models, we reviewed the latest strategy in searching optimal dose combination from three perspectives: (1) mainly experimental-based approach; (2) Computational-guided experimental approach; and (3) mainly computational-based approach. In addition to the introduction of each strategy, critical discussion of their advantages and disadvantages were also included, with a strong focus on the current applications and future improvements.

Molecular mechanism of action and potential biomarkers of growth inhibition of synergistic combination of afatinib and dasatinib against gefitinib-resistant non-small cell lung cancer cells

Epidermal growth factor receptor - tyrosine kinase inhibitor (EGFR-TKI) is the first choice of treatment for advanced non-small cell lung cancer (NSCLC) patients harbouring activating EGFR mutations. However, single agent usually has limited efficacy due to heterogeneous resistant mechanisms of cancer cells. Thus drug combination therapy would offer more benefits by synergistic interactions and avoidance of resistance emergence. In this study, we selected 8 NSCLC cell lines with different genetic characteristics as research models to investigate the efficacy of 4 agents (gefitinib, cetuximab, afatinib and dasatinib) and their combinations. As a single agent, both afatinib and dasatinib showed more inhibition against cell proliferation than gefitinib and cetuximab. Afatinib combined with dasatinib demonstrated significantly high efficacy against 7 gefitinib-resistant NSCLC cell lines. Moreover, it reversed the resistance to the 4 studied single agents in PTEN mutated NSCLC cells. By studying the activity of EGFR, Src and their downstream signalling pathways including PI3K/PTEN/Akt, Ras/Raf/MEK/ERK, Src/FAK and JAK/Stat, we demonstrated the synergistic interaction between afatinib and dasatinib was not only due to their blockage of different signalling pathways but also the complemental inhibition of the related signalling molecules such as Stat3. We also found that the level of Src, Stat3, and MAPK may be useful biomarkers predicating synergism between afatinib and dasatinib for the treatment of gefitinib-resistant NSCLC cells.

Berberine and Evodiamine Act Synergistically Against Human Breast Cancer MCF-7 Cells by Inducing Cell Cycle Arrest and Apoptosis

BACKGROUND/AIM

The synergistic combinations of natural products have long been the basis of Traditional Chinese herbal Medicine formulas. In this study, we investigated the synergistic effects of a combination of berberine and evodiamine against human breast cancer MCF-7 cells in vitro and in vivo, and explored its mechanism.

MATERIALS AND METHODS

Cell survival was measured using the MTT assay. Apoptosis-related proteins were observed using western blot analysis. Apoptosis was detected with flow cytometric analysis and by Hoechst 33258 staining. Tumor xenografts were used in vivo.

RESULTS

Compared to berberine or evodiamine treatments alone, the combination treatment of berberine (25 μM) and evodiamine (15 μM) synergistically inhibited the proliferation of MCF-7 cells in a time-dependent manner and resulted in the G₀/G₁ phase accumulation of cells that exhibited increased expression levels of the CDK inhibitors p21 and p27 with a concomitant reduction in the expression levels of cell-cycle checkpoint proteins cyclin D1, cyclin E, CDK4, and CDK6. Furthermore, the combination treatment induced apoptosis that was accompanied by increased expression levels of p53 and Bax, reduced expression levels of Bcl-2, activation of caspase-7, and caspase-9, and the cleavage of PARP. The combination of berberine and evodiamine synergistically inhibited tumor growth in vivo in MCF-7 human breast cancer xenografts.

CONCLUSION

Combination of berberine and evodiamine acts synergistically to suppress the proliferation of MCF-7 cells by inducing cell cycle arrest and apoptosis, illustrating the potential synergistic and combinatorial application of bioactive natural products.

Sequential Exposure of Bortezomib and Vorinostat is Synergistic in Multiple Myeloma Cells

PURPOSE

To examine the combination of bortezomib and vorinostat in multiple myeloma cells (U266) and xenografts, and to assess the nature of their potential interactions with semi-mechanistic pharmacodynamic models and biomarkers.

METHODS

U266 proliferation was examined for a range of bortezomib and vorinostat exposure times and concentrations (alone and in combination). A non-competitive interaction model was used with interaction parameters that reflect the nature of drug interactions after simultaneous and sequential exposures. p21 and cleaved PARP were measured using immunoblotting to assess critical biomarker dynamics. For xenografts, data were extracted from literature and modeled with a PK/PD model with an interaction parameter.

RESULTS

Estimated model parameters for simultaneous in vitro and xenograft treatments suggested additive drug effects. The sequence of bortezomib preincubation for 24 hours, followed by vorinostat for 24 hours, resulted in an estimated interaction term significantly less than 1, suggesting synergistic effects. p21 and cleaved PARP were also up-regulated the greatest in this sequence.

CONCLUSIONS

Semi-mechanistic pharmacodynamic modeling suggests synergistic pharmacodynamic interactions for the sequential administration of bortezomib followed by vorinostat. Increased p21 and cleaved PARP expression can potentially explain mechanisms of their enhanced effects, which require further PK/PD systems analysis to suggest an optimal dosing regimen.

Synergistic combinations of tanshinone IIA and trans-resveratrol toward cisplatin-comparable cytotoxicity in HepG2 human hepatocellular carcinoma cells

AIM

To determine the combinative effects of tanshinone IIA (Tan IIA) and trans-resveratrol (Resv) on cytotoxicity, apoptosis, cell-cycle arrest and DNA fragmentation in HepG2 human liver cancer cells.

MATERIALS AND METHODS

Cytotoxicity was detected by the cell proliferation and cytotoxicity WST-1 assay. Cell-cycle arrest and apoptosis were determined using flow cytometry analysis. DNA fragments were separated by gel electrophoresis.

RESULTS

Tan IIA and Resv at mixture ratios of 1/2:1/2 and 1/3:2/3 exerted synergistic cytotoxicity comparable to that of cisplatin. Elevated proportions of sub-G1 and apoptotic cells were respectively found in the combinative treatments in comparison with hypothetic values of additive effects. Moreover, a more intensive pattern of apoptotic DNA fragmentation was visualized in combined treatments than in individual ones.

CONCLUSION

Combining Tan IIA and Resv causes synergistic cisplatin-comparable, cytotoxicity and robustly induces apoptosis, sub-G1 cell cycle arrest and DNA fragmentation. This study provides evidence supporting further pre-clinical investigations of the combinational synergism.