Polymeric Micellar Formulation Enhances Antimicrobial and Anticancer Properties of Salinomycin

Dual targeting salinomycin-loaded smart nanomicelles for enhanced accumulation and therapeutic outcome in breast cancer

Salinomycin is a polyether compound that exhibits strong anticancer activity and is known as the cancer stem cell inhibitor that reached clinical testing. The rapid elimination of nanoparticles from the bloodstream by the mononuclear phagocyte system (MPS), the liver, and the spleen, accompanied by protein corona (PC) formation, restricts in vivo delivery of nanoparticles in the tumor microenvironment (TME). The DNA aptamer (TA1) that successfully targets the overexpressed CD44 antigen on the surface of breast cancer cells suffers strongly from PC formation in vivo. Thus, cleverly designed targeted strategies that lead to the accumulation of nanoparticles in the tumor become a top priority in the drug delivery field. In this work, dual redox/pH-sensitive poly (β-amino ester) copolymeric micelles modified with CSRLSLPGSSSKpalmSSS peptide and TA1 aptamer, as dual targeting ligands, were synthesized and fully characterized by physico-chemical methods. These biologically transformable stealth NPs were altered into the two ligand-capped (SRL-2 and TA1) NPs for synergistic targeting of the 4T1 breast cancer model after exposure to the TME. The PC formation was reduced sharply in Raw 264.7 cells by increasing the CSRLSLPGSSSKpalmSSS peptide concentration in modified micelles. Surprisingly, in vitro and in vivo biodistribution findings showed that dual targeted micelle accumulation in the TME of 4T1 breast cancer model was significantly higher than that of single modified formulation, along with deep penetration 24 h after intraperitoneal injection. Also, an in vivo treatment study showed remarkable tumor growth inhibition in 4T1 tumor-bearing Balb/c mice, compared to different formulations, with a 10% lower therapeutic dose (TD) of SAL that was confirmed by hematoxylin and eosin staining (H&E) and the TUNEL assay. Overall, in this study, we developed smart transformable NPs in which the body's own engineering systems alter their biological identity, which resulted in a reduction in therapeutic dosage along with a lowered off-target effect.

ABC Transporters and CYP3A4 Mediate Drug Interactions between Enrofloxacin and Salinomycin Leading to Increased Risk of Drug Residues and Resistance

Enrofloxacin (ENR) is one of the most common drugs used in poultry production to treat bacterial diseases, and there is a high risk of drug interactions (DDIs) between polyether anticoccidial drugs added to poultry feed over time. This may affect the efficacy of antibiotics or lead to toxicity, posing a potential risk to the environment and food safety. This study aimed to investigate the DDI of ENR and salinomycin (SAL) in broilers and the mechanism of their DDI. We found that SAL increased the area under the curve and elimination half-life of ENR and ciprofloxacin (CIP) by 1.3 and 2.4 times, 1.2 and 2.5 times, respectively. Cytochrome 3A4 (CYP3A4), p-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) were important factors for the DDI between ENR and SAL in broilers. ENR and SAL are substrates of CYP3A4, P-gp and BCRP in broilers; ENR and SAL inhibited the expression of CYP3A4 activity in a time- and concentration-dependent. Meanwhile, ENR downregulated the expression of P-gp and BCRP in a time- and concentration-dependent manner. A single oral administration of SAL inhibited CYP3A4, P-gp, and BCRP, but long-term mixed feeding upregulated the expression of CYP3A4, P-gp, and BCRP. Molecular docking revealed that ENR and SAL compete with each other for CYP3A4 to affect hepatic metabolism, and compete with ATP for P-gp and BCRP binding sites to inhibit efflux. ENR and SAL in broilers can lead to severe DDI. Drug residues and resistance following co-administration of ENR and SAL and other SAL-based drug-feed interactions warrant further study.

Nano-Enabled Strategies for the Treatment of Lung Cancer: Potential Bottlenecks and Future Perspectives

On a global scale, lung cancer is acknowledged to be the major driver of cancer death attributable to treatment challenges and poor prognosis. Classical cancer treatment regimens, such as chemotherapy or radiotherapy, can be used to treat lung cancer, but the appended adverse effects limit them. Because of the numerous side effects associated with these treatment modalities, it is crucial to strive to develop novel and better strategies for managing lung cancer. Attributes such as enhanced bioavailability, better in vivo stability, intestinal absorption pattern, solubility, prolonged and targeted distribution, and the superior therapeutic effectiveness of numerous anticancer drugs have all been boosted with the emergence of nano-based therapeutic systems. Lipid-based polymeric and inorganic nano-formulations are now being explored for the targeted delivery of chemotherapeutics for lung cancer treatment. Nano-based approaches are pioneering the route for primary and metastatic lung cancer diagnosis and treatment. The implementation and development of innovative nanocarriers for drug administration, particularly for developing cancer therapies, is an intriguing and challenging task in the scientific domain. The current article provides an overview of the delivery methods, such as passive and active targeting for chemotherapeutics to treat lung cancer. Combinatorial drug therapy and techniques to overcome drug resistance in lung cancer cells, as potential ways to increase treatment effectiveness, are also discussed. In addition, the clinical studies of the potential therapies at different stages and the associated challenges are also presented. A summary of patent literature has also been included to keep readers aware of the new and innovative nanotechnology-based ways to treat lung cancer.

Salinomycin as a potent anticancer stem cell agent: State of the art and future directions

Cancer stem cells (CSCs) are a small subpopulation of cells within a tumor that can both self‐renew and differentiate into other cell types forming the heterogeneous tumor bulk. Since CSCs are involved in all aspects of cancer development, including tumor initiation, cell proliferation, metastatic dissemination, therapy resistance, and recurrence, they have emerged as attractive targets for cancer treatment and management. Salinomycin, a widely used antibiotic in poultry farming, was identified by the Weinberg group as a potent anti‐CSC agent in 2009. As a polyether ionophore, salinomycin exerts broad‐spectrum activities, including the important anti‐CSC function. Studies on the mechanism of action of salinomycin against cancer have been continuously and rapidly published since then. Thus, it is imperative for us to update its literature of recent research findings in this area. We here summarize the notable work reported on salinomycin's anticancer activities, intracellular binding target(s), effects on tumor microenvironment, safety, derivatives, and tumor‐specific drug delivery; after that we also discuss the translational potential of salinomycin toward clinical application based on current multifaceted understandings.

Salinomycin-Based Drug Delivery Systems: Overcoming the Hurdles in Cancer Therapy

Cancer stem cells (CSCs) are reportedly responsible for the initiation and propagation of cancer. Since CSCs are highly resistant to conventional chemo- and radiotherapy, they are considered the main cause of cancer relapse and metastasis. Salinomycin (Sali), an anticoccidial polyether antibiotic, has emerged as a promising new candidate for cancer therapy, with selective cytotoxicity against CSCs in various malignancies. Nanotechnology provides an efficient means of delivering Sali to tumors in view of reducing collateral damage to healthy tissues and enhancing the therapeutic outcome. This review offers an insight into the most recent advances in cancer therapy using Sali-based nanocarriers.

Nanoapproaches to Modifying Epigenetics of Epithelial Mesenchymal Transition for Treatment of Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronically progressive interstitial lung that affects over 3 M people worldwide and rising in incidence. With a median survival of 2-3 years, IPF is consequently associated with high morbidity, mortality, and healthcare burden. Although two antifibrotic therapies, pirfenidone and nintedanib, are approved for human use, these agents reduce the rate of decline of pulmonary function but are not curative and do not reverse established fibrosis. In this review, we discuss the prevailing epithelial injury hypothesis, wherein pathogenic airway epithelial cell-state changes known as Epithelial Mesenchymal Transition (EMT) promotes the expansion of myofibroblast populations. Myofibroblasts are principal components of extracellular matrix production that result in airspace loss and mortality. We review the epigenetic transition driving EMT, a process produced by changes in histone acetylation regulating mesenchymal gene expression programs. This mechanistic work has focused on the central role of bromodomain-containing protein 4 in mediating EMT and myofibroblast transition and initial preclinical work has provided evidence of efficacy. As nanomedicine presents a promising approach to enhancing the efficacy of such anti-IPF agents, we then focus on the state of nanomedicine formulations for inhalable delivery in the treatment of pulmonary diseases, including liposomes, polymeric nanoparticles (NPs), inorganic NPs, and exosomes. These nanoscale agents potentially provide unique properties to existing pulmonary therapeutics, including controlled release, reduced systemic toxicity, and combination delivery. NP-based approaches for pulmonary delivery thus offer substantial promise to modify epigenetic regulators of EMT and advance treatments for IPF.

Triclosan-loaded pH-responsive copolymer to target bacteria and to have long bacteriostatic efficacy

It is important to reduce side effects and to explore novel usage for hydrophobic broad-spectrum antibacterial agent triclosan (TCS). In this study, a new amphiphilic copolymer with tertiary amine groups, monomethyl ether poly(ethylene glycol)-b-poly{α-[4-(diethylamino)methyl-1,2,3-triazol]-caprolactone-co-caprolactone} (mPEG-PDCL) was designed and synthesized, and its micelles were applied as carries of TCS to enhance antimicrobial and bacteriostatic action. mPEG-PDCL and its contrastive copolymer mPEG-PCL could form uniform spherical micelles with sizes 50-110 nm. The zeta potential of mPEG-PDCL micelles was positive and changed from 7.00 ± 0.67 mV at pH 7.5 to 24.67 ± 1.23 mV at pH 5.5. Both TCS-loaded micelles displayed quite high drug loading content (approx. 15%) and drug loading efficiency (more than 85%). In comparison with pH 7.4, TCS released faster in acidic environment which was induced by bacteria metabolism. MIC values of both TCS-loaded micelles against S. aureus and E. coli were as low as free TCS. TCS-loaded micelles showed much better antibacterial activity than free TCS, especially, mPEG-PDCL/TCS micelles displayed long bacteriostatic efficacy in 60 h against S. aureus and in 54 h against E. coli. mPEG-PDCL micelles preferred targeting to both S. aureus and E. coli due to positive zeta potential. In in vivo experiment, the purulence of the infected wound almost disappeared for SD rats treated with mPEG-PDCL/TCS micelles. Therefore, mPEG-PDCL micelles may be used as good carriers for antimicrobial agents, and the TCS-loaded micelles possess long antimicrobial/bacteriostatic efficacy.

Nanomaterials as Inhibitors of Epithelial Mesenchymal Transition in Cancer Treatment

Abstract: Epithelial-mesenchymal transition (EMT) has emerged as a key regulator of cell invasion and metastasis in cancers. Besides the acquisition of migratory/invasive abilities, the EMT process is tightly connected with the generation of cancer stem cells (CSCs), thus contributing to chemoresistance. However, although EMT represents a relevant therapeutic target for cancer treatment, its application in the clinic is still limited due to various reasons, including tumor-stage heterogeneity, molecular-cellular target specificity, and appropriate drug delivery. Concerning this last point, different nanomaterials may be used to counteract EMT induction, providing novel therapeutic tools against many different cancers. In this review, (1) we discuss the application of various nanomaterials for EMT-based therapies in cancer, (2) we summarize the therapeutic relevance of some of the proposed EMT targets, and (3) we review the potential benefits and weaknesses of each approach.

Poloxamer Hydrogels for Biomedical Applications

This review article focuses on thermoresponsive hydrogels consisting of poloxamers which are of high interest for biomedical application especially in drug delivery for ophthalmic, injectable, transdermal, and vaginal administration. These hydrogels remain fluid at room temperature but become more viscous gel once they are exposed to body temperature. In this way, the gelling system remains at the topical level for a long time and the drug release is controlled and prolonged. Poloxamers are synthetic triblock copolymers of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO), also commercially known as Pluronics®, Synperonics® or Lutrol®. The different poloxamers cover a range of liquids, pastes, and solids, with molecular weights and ethylene oxide-propylene oxide weight ratios varying from 1100 to 14,000 and 1:9 to 8:2, respectively. Concentrated aqueous solutions of poloxamers form thermoreversible gels. In recent years this type of gel has arouse interest for tissue engineering. Finally, the use of poloxamers as biosurfactants is evaluated since they are able to form micelles in an aqueous environment above a concentration threshold known as critical micelle concentration (CMC). This property is exploited for drug delivery and different therapeutic applications.