Synthesis and biological activities of a 3'-azido analogue of Doxorubicin against drug-resistant cancer cells

Novel N,N-Dimethyl-idarubicin Analogues Are Effective Cytotoxic Agents for ABCB1-Overexpressing, Doxorubicin-Resistant Cells

Anthracyclines comprise one of the most effective anticancer drug classes. Doxorubicin, daunorubicin, epirubicin, and idarubicin have been in clinical use for decades, but their application remains complicated by treatment-related toxicities and drug resistance. We previously demonstrated that the combination of DNA damage and histone eviction exerted by doxorubicin drives its associated adverse effects. However, whether the same properties dictate drug resistance is unclear. In the present study, we evaluate a library of 40 anthracyclines on their cytotoxicity, intracellular uptake, and subcellular localization in K562 wildtype versus ABCB1-transporter-overexpressing, doxorubicin-resistant cells. We identify several highly potent cytotoxic anthracyclines. Among these, N,N-dimethyl-idarubicin and anthracycline (composed of the idarubicin aglycon and the aclarubicin trisaccharide) stand out, due to their histone eviction-mediated cytotoxicity toward doxorubicin-resistant cells. Our findings thus uncover understudied anthracycline variants warranting further investigation in the quest for safer and more effective anticancer agents that circumvent cellular export by ABCB1.

Re-Exploring the Anthracycline Chemical Space for Better Anti-Cancer Compounds

The anthracycline anti-cancer drugs are intensely used in the clinic to treat a wide variety of cancers. They generate DNA double strand breaks, but recently the induction of chromatin damage was introduced as another major determinant of anti-cancer activity. The combination of these two events results in their reported side effects. While our knowledge on the structure-activity relationship of anthracyclines has improved, many structural variations remain poorly explored. Therefore, we here report on the preparation of a diverse set of anthracyclines with variations within the sugar moiety, amine alkylation pattern, saccharide chain and aglycone. We assessed the cytotoxicity in vitro in relevant human cancer cell lines, and the capacity to induce DNA- and chromatin damage. This coherent set of data allowed us to deduce a few guidelines on anthracycline design, as well as discover novel, highly potent anthracyclines that may be better tolerated by patients.

Thiosemicarbazones Can Act Synergistically with Anthracyclines to Downregulate CHEK1 Expression and Induce DNA Damage in Cell Lines Derived from Pediatric Solid Tumors

Anticancer therapy by anthracyclines often leads to the development of multidrug resistance (MDR), with subsequent treatment failure. Thiosemicarbazones have been previously suggested as suitable anthracycline partners due to their ability to overcome drug resistance through dual Pgp-dependent cytotoxicity-inducing effects. Here, we focused on combining anthracyclines (doxorubicin, daunorubicin, and mitoxantrone) and two thiosemicarbazones (DpC and Dp44mT) for treating cell types derived from the most frequent pediatric solid tumors. Our results showed synergistic effects for all combinations of treatments in all tested cell types. Nevertheless, further experiments revealed that this synergism was independent of Pgp expression but rather resulted from impaired DNA repair control leading to cell death via mitotic catastrophe. The downregulation of checkpoint kinase 1 (CHEK1) expression by thiosemicarbazones and the ability of both types of agents to induce double-strand breaks in DNA may explain the Pgp-independent synergism between anthracyclines and thiosemicarbazones. Moreover, the concomitant application of these agents was found to be the most efficient approach, achieving the strongest synergistic effect with lower concentrations of these drugs. Overall, our study identified a new mechanism that offers an avenue for combining thiosemicarbazones with anthracyclines to treat tumors regardless the Pgp status.

Hypervalent Iodine Mediated Oxidation Followed by Acetoxylation / Tosylation of α-Substituted Benzylamines Accessing to α-Acyloxy / Tosyloxy Ketones

An efficient and metal-free method has been developed for sequential oxidation followed by acetoxylation, tosylation of α-alkylbenzylamines for the synthesis of α-acyloxy / tosyloxy ketones by using hypervalent iodine (III)...

Structure-based drug repurposing to inhibit the DNA gyrase of Mycobacterium tuberculosis

Drug repurposing is an alternative avenue for identifying new drugs to treat tuberculosis (TB). Despite the broad-range of anti-tubercular drugs, the emergence of multi-drug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis (Mtb) H37Rv, as well as the significant death toll globally, necessitates the development of new and effective drugs to treat TB. In this study, we have employed a drug repurposing approach to address this drug resistance problem by screening the drugbank database to identify novel inhibitors of the Mtb target enzyme, DNA gyrase. The compounds were screened against the ATPase domain of the gyrase B subunit (MtbGyrB47), and the docking results showed that echinacoside, doxorubicin, epirubicin, and idarubicin possess high binding affinities against MtbGyrB47. Comprehensive assessment using fluorescence spectroscopy, surface plasmon resonance spectroscopy (SPR), and circular dichroism (CD) titration studies revealed echinacoside as a potent binder of MtbGyrB47. Furthermore, ATPase, and DNA supercoiling assays exhibited an IC50 values of 2.1-4.7 µM for echinacoside, doxorubicin, epirubicin, and idarubicin. Among these compounds, the least MIC90 of 6.3 and 12 μM were observed for epirubicin and echinacoside, respectively, against Mtb. Our findings indicate that echinacoside and epirubicin targets mycobacterial DNA gyrase, inhibit its catalytic cycle, and retard mycobacterium growth. Further, these compounds exhibit potential scaffolds for optimizing novel anti-mycobacterial agents that can act on drug-resistant strains.

Antitumour Anthracyclines: Progress and Perspectives

Anthracyclines are ranked among the most effective chemotherapeutics against cancer. They are glycoside drugs comprising the amino sugar daunosamine linked to a hydroxy anthraquinone aglycone, and act by DNA intercalation, oxidative stress generation and topoisomerase II poisoning. Regardless of their therapeutic value, multidrug resistance and severe cardiotoxicity are important limitations of anthracycline treatment that have prompted the discovery of novel analogues. This review covers the most clinically relevant anthracyclines and their development over decades, since the first discovered natural prototypes to recent semisynthetic and synthetic derivatives. These include registered drugs, drug candidates undergoing clinical trials, and compounds under pre-clinical investigation. The impact of the structural modifications on antitumour activity, toxicity and resistance profile is addressed.

Metabolic and non-metabolic pathways that control cancer resistance to anthracyclines

Anthracyclines Doxorubicin, Epirubicin, Daunorubicin and Idarubicin are used to treat a variety of tumor types in the clinics, either alone or, most often, in combination therapies. While their cardiotoxicity is well known, the emergence of chemoresistance is also a major issue accounting for treatment discontinuation. Resistance to anthracyclines is associated to the acquisition of multidrug resistance conferred by overexpression of permeability glycoprotein-1 or other efflux pumps, by altered DNA repair, changes in topoisomerase II activity, cancer stemness and metabolic adaptations. This review further details the metabolic aspects of resistance to anthracyclines, emphasizing the contributions of glycolysis, the pentose phosphate pathway and nucleotide biosynthesis, glutathione, lipid metabolism and autophagy to the chemoresistant phenotype.

Preparation and evaluation of highly biocompatible nanogels with pH-sensitive charge-convertible capability based on doxorubicin prodrug

In this paper, to achieve the targeted ability of anti-tumor drug doxorubicin (DOX), enhance the treatment effect and reduce the side effect, a novel pH-sensitive and charge-convertible prodrug nanogel was prepared. Firstly, cis-aconitic anhydride-doxorubicin prodrug (CAD) and Pluronic F127-chitosan-CAD (F127-CS-CAD) conjugates were synthesized. Then the DOX loaded polyion complex micelles (F127-CS-CAD/CAD) were prepared by self-assembling, thus CAD was incorporated into micelles via electrostatic interactions between electronegative CAD and positively charged F127-CS-CAD and hydrophobic interactions. Finally a pH-responsive charge-convertible copolymer, folic acid modified gelatin (Gel-FA) was shielded on the surface of micelles and the Gel-FA/F127-CS-CAD/CAD nanogel was formed, the charge-convertible capability was evaluated through changes of the morphology and Zeta potential under different pH value environment by transmission electron microscopy (TEM) and Zeta potential analyzer. And in vitro pH-dependent and two-phase drug release from nanogel was also evaluated. In vitro anti-tumor activity of Gel-FA/F127-CS-CAD/CAD nanogel was performed on HeLa cells and HepG2 cells to prove the strong cell toxicity of nanogels. Finally, the in vivo safety experiments showed that the nanogel achieved the reducing the toxic side effects of DOX significantly.

Methods for 2-Deoxyglycoside Synthesis

Deoxy-sugars often play a critical role in modulating the potency of many bioactive natural products. Accordingly, there has been sustained interest in methods for their synthesis over the past several decades. The focus of much of this work has been on developing new glycosylation reactions that permit the mild and selective construction of deoxyglycosides. This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter. Where relevant, the application of this chemistry to natural product synthesis will also be described.

Doxorubicin-conjugated dexamethasone induced MCF-7 apoptosis without entering the nucleus and able to overcome MDR-1-induced resistance

Background

Doxorubicin (DOX) is the most widely used chemotherapeutic agent that has multimodal cytotoxicity. The main cytotoxic actions of DOX occur in the nucleus. The emergence of drug-resistant cancer cells that have the ability to actively efflux DOX out of the nucleus, and the cytoplasm has led to the search for a more effective derivative of this drug.

Materials and methods

We created a new derivative of DOX that was derived via simple conjugation of the 3' amino group of DOX to the dexamethasone molecule.

Results

Despite having a lower cytotoxic activity in MCF-7 cells, the conjugated product, DexDOX, exerted its actions in a manner that was different to that of DOX. DexDOX rapidly induced MCF-7 cell apoptosis without entering the nucleus. Further analysis showed that Dex-DOX increased cytosolic oxidative stress and did not interfere with the cell cycle. In addition, the conjugated product retained its cytotoxicity in multidrug resistance-1-overexpressing MCF-7 cells that had an approximately 16-fold higher resistance to DOX.

Conclusion

We have synthesized a new derivative of DOX, which has the ability to overcome multidrug resistance-1-induced resistance. This molecule may have potential as a future chemotherapeutic agent.

Antimycobacterial activity of DNA intercalator inhibitors of Mycobacterium tuberculosis primase DnaG

Owing to the rise in drug resistance in tuberculosis combined with the global spread of its causative pathogen, Mycobacterium tuberculosis (Mtb), innovative anti mycobacterial agents are urgently needed. Recently, we developed a novel primase-pyrophosphatase assay and used it to discover inhibitors of an essential Mtb enzyme, primase DnaG (Mtb DnaG), a promising and unexplored potential target for novel antituberculosis chemotherapeutics. Doxorubicin, an anthracycline antibiotic used as an anticancer drug, was found to be a potent inhibitor of Mtb DnaG. In this study, we investigated both inhibition of Mtb DnaG and the inhibitory activity against in vitro growth of Mtb and M. smegmatis (Msm) by other anthracyclines, daunorubicin and idarubicin, as well as by less cytotoxic DNA intercalators: aloe-emodin, rhein and a mitoxantrone derivative. Generally, low-μM inhibition of Mtb DnaG by the anthracyclines was correlated with their low-μM minimum inhibitory concentrations. Aloe-emodin displayed threefold weaker potency than doxorubicin against Mtb DnaG and similar inhibition of Msm (but not Mtb) in the mid-μM range, whereas rhein (a close analog of aloe-emodin) and a di-glucosylated mitoxantrone derivative did not show significant inhibition of Mtb DnaG or antimycobacterial activity. Taken together, these observations strongly suggest that several clinically used anthracyclines and aloe-emodin target mycobacterial primase, setting the stage for a more extensive exploration of this enzyme as an antibacterial target.