Epigenetic dysregulation has been recognized as a critical factor contributing to the development of resistance against standard chemotherapy and to breast cancer progression via epithelial-to-mesenchymal transition. Although the efficacy of the first-generation epigenetic drugs (epi-drugs) in solid tumor management has been disappointing, there is an increasing body of evidence showing that epigenome modulation, in synergy with other therapeutic approaches, could play an important role in cancer treatment, reversing acquired therapy resistance. However, the epigenetic therapy of solid malignancies is not straightforward. The emergence of nanotechnologies applied to medicine has brought new opportunities to advance the targeted delivery of epi-drugs while improving their stability and solubility, and minimizing off-target effects. Furthermore, the omics technologies, as powerful molecular epidemiology screening tools, enable new diagnostic and prognostic epigenetic biomarker identification, allowing for patient stratification and tailored management. In combination with new-generation epi-drugs, nanomedicine can help to overcome low therapeutic efficacy in treatment-resistant tumors. This review provides an overview of ongoing clinical trials focusing on combination therapies employing epi-drugs for breast cancer treatment and summarizes the latest nano-based targeted delivery approaches for epi-drugs. Moreover, it highlights the current limitations and obstacles associated with applying these experimental strategies in the clinics.

Seventeen 1,4-dihydropyridine (1,4-DHP) amphiphiles including differently substituted pyridinium, pyrazinium, N-methyl piperidinium or N-methyl morpholinium moieties as the cationic head-group of the molecule have been designed and synthesised. 1,4-DHP amphiphiles have been earlier proposed as a promising tool for plasmid DNA (pDNA) delivery in vitro. In this work the ability of the 1,4-DHP amphiphiles to self-assemble, to bind pDNA and to transfer it into the cells as well as the cytotoxicity of 1,4-DHP amphiphiles–pDNA complexes was studied. Furthermore, antiradical activity (ARA) of the 1,4-DHP derivatives was determined. We have revealed that all new 1,4-DHP amphiphiles possessed self-assembling properties and formed nanoparticles in an aqueous environment. The structure of the cationic head-group of 1,4-DHP amphiphiles influenced the size of nanoparticles. Additionally, we demonstrated for the first time that the electronic nature of the substituent of the pyridinium as the cationic head-group of the 1,4-DHP amphiphiles strongly affected the ability of these compounds to bind pDNA and transfer it into the cells. The amphiphiles with electron-donating properties possessing substituents at pyridinium moieties were able to bind pDNA and to deliver it more efficiently than amphiphiles containing electron-withdrawing properties possessing substituents at pyridinium moieties. Moreover, in this study we have established that the presence of the cationic part in the molecule was essential for the expression of ARA among tested 1,4-DHP amphiphiles. Cationic 1,4-DHP derivatives containing pyrazinium or N-methyl morpholinium substituents in the cationic head-group of the molecule displayed the highest ARA.

The novel 1,4-dihydropyridine derivatives containing the cationic pyridine moiety at the position 4, and the N -propargyl group as a substituent at position 1 of the 1,4-DHP cycle were designed, synthesised, and assessed in biological tests. Among all the novel compounds, the 4-( N -dodecyl) pyridinium group-containing compounds 11 (without the N -propargyl group) and 12 (with the N -propargyl group) demonstrated the highest calcium antagonistic properties against neuroblastoma SH-SY5Y (IC ₅₀ about 5–14 μM) and the vascular smooth muscle A7r5 cell (IC ₅₀ – 0.6–0.7 μM) lines, indicating that they predominantly target the L-type calcium channels. These compounds showed a slight total antioxidant activity. At concentrations close to those of L-type calcium channel blocking ones, compound 12 did not affect mitochondrial functioning; also, no toxicity was obtained in vivo. The N -propargyl group as a substituent at position 1 of the 1,4-DHP cycle did not essentially influence the compounds’ activity. The 4-( N -dodecyl) pyridinium moiety-containing compounds can be considered as prototype molecules for further chemical modifications and studies as cardioprotective/neuroprotective agents.

The synthesis of cationic amphiphilic 1,4-dihydropyridine derivative, potential gene delivery agent is achieved via an efficient multi-step sequence. The key step of this approach is a two-component Hantzsch type cyclisation of 3-oxo-2-[1-phenylmethylidene]-butyric acid dodecyl ester and 3-amino-but-2-enoic acid dodecyl ester utilising bis(2-hydroxyethyl)ether as a solvent and 1-butyl-4-methylpyridinium chloride as a catalyst. The 1,4-dihydropyridine derivative with long alkyl ester chains at positions 3 and 5 of the 1,4-DHP ring — 3,5-bis(dodecyloxycarbonyl)-2,6-dimethyl-4-phenyl-1,4-dihydropyridine was obtained in substantially higher yield with respect to classical Hantzsch synthesis. Bromination of this compound followed by nucleophilic substitution of bromine with pyridine gave the desired cationic amphiphilic 1,4-dihydropyridine.

Gentamicin is an essential broad-spectrum aminoglycoside antibiotic that is used in over 40 clinical conditions and has shown activity against a wide range of nosocomial, biofilm-forming, multi-drug resistant bacteria. Nevertheless, the low cellular penetration and serious side effects of gentamicin, as well as the fear of the development of antibacterial resistance, has led to a search for ways to circumvent these obstacles. This review provides an overview of the chemical and pharmacological properties of gentamicin and offers six different strategies (the isolation of specific types of gentamicin, encapsulation in polymeric nanoparticles, hydrophobization of the gentamicin molecule, and combinations of gentamicin with other antibiotics, polyphenols, and natural products) that aim to enhance the drug delivery and antibacterial activity of gentamicin. In addition, factors influencing the synthesis of gentamicin-loaded polymeric (poly (lactic-co-glycolic acid) (PLGA) and chitosan) nanoparticles and the methods used in drug release studies are discussed. Potential research directions and future perspectives for gentamicin-loaded drug delivery systems are given.