Relationships between DNA strand breakage and apoptotic progression upon treatment of HL-60 leukemia cells with tafluposide or etoposide

Copper-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine based triazole-linked glycohybrids: mechanistic insights and bio-applications

Hybrid molecules maintain their stronghold in the drug market, with over 60% of drug candidates in pharmaceutical industries. The substantial expenses for developing and producing biologically privileged drugs are expected to create opportunities for producing hybrid molecule-based drugs. Therefore, we have developed a simple and efficient copper-catalyzed approach for synthesizing a wide range of triazole-linked glycohybrids derived from pyrazolo[1,5-a]pyrimidines. Employing a microwave-assisted copper-catalyzed approach, we developed a concise route using various 7-O-propargylated pyrazolo[1,5-a]pyrimidines and 1-azidoglycosides. This strategy afforded a series of twenty-seven glycohybrids up to 98% yield with diverse stereochemistry. All were achieved within a remarkably shortened time frame. Our investigation extends to evaluating the anticancer potential of these synthesized triazole-linked pyrazolo[1,5-a] pyrimidine-based glycohybrids. In-vitro assays against MCF-7, MDA-MB231, and MDA-MB453 cell lines reveal intriguing findings. (2R,3S,4S,5R,6R)-2-(acetoxymethyl)-6-(4-(((5-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-7-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate emerges as a standout with better anticancer activity against MDA-MB231 cells (IC50 = 29.1 µM), while (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(4-(((5-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-7-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate demonstrates the best inhibitory effects against MCF-7 cells (IC50 = 15.3 µM) in all derived compounds. These results align with our docking analysis and structure-activity relationship (SAR) investigations, further validating the in-vitro outcomes. This work not only underscores the synthetic utility of our devised protocol but also highlights the promising potential of these glycohybrids as candidates for further anticancer therapeutic exploration.

Synthesis of triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones as anticancer agents and their in silico docking studies

In the pursuit of novel therapeutic agents, we present a comprehensive study on the design, synthesis, and evaluation of a diverse library of triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones, employing a microwave-assisted synthetic approach via 'click chemistry'. This methodology offers efficient and accelerated access to the glycohybrids, showcasing improved reaction conditions that yield high-quality products. In this research endeavor, we have successfully synthesized a series of twenty-seven triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones. Our investigation extends beyond synthetic endeavors to explore the potential therapeutic relevance of these compounds. We subjected them to rigorous in vitro screening against prominent breast cancer cell lines MCF-7, MDA-MB231, and MDA-MB453. Among the library of compounds synthesized, (2S,3S,4R,5S,6S)-2-(acetoxymethyl)-6-(4-((5-(4-methoxyphenyl)-7-oxopyrazolo[1,5-a]pyrimidin-1(7H)-yl)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate emerged as a potent compound, exhibiting remarkable anti-cancer activity with an IC50 value of 27.66 μM against the MDA-MB231 cell line. Additionally, (2S,3R,4R,5S,6S)-2-(acetoxymethyl)-6-(4-((7-oxo-5-(4-(trifluoromethyl)phenyl)pyrazolo[1,5-a]pyrimidin-1(7H)-yl)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate displayed notable inhibitory potential against the MCF-7 cell line, with an IC50 value of 4.93 μM. Furthermore, in silico docking analysis was performed to validate our experimental findings. These findings underscore the promise of our triazole bridged N-glycosides of pyrazolo[1,5-a]pyrimidinones as potential anti-cancer agents. This research not only enriches the field of glycohybrid synthesis but also contributes valuable insights into the development of novel anti-cancer therapeutics.

Dual Inhibitors as a New Challenge for Cancer Multidrug Resistance Treatment

BACKGROUND

Dual-targeting in cancer treatment by a single drug is an unconventional approach in relation to drug combinations. The rationale for the development of dualtargeting agents is to overcome incomplete efficacy and drug resistance frequently present when applying individual targeting agents. Consequently, -a more favorable outcome of cancer treatment is expected with dual-targeting strategies.

METHODS

We reviewed the literature, concentrating on the association between clinically relevant and/or novel dual inhibitors with the potential to modulate multidrug resistant phenotype of cancer cells, particularly the activity of P-glycoprotein. A balanced analysis of content was performed to emphasize the most important findings and optimize the structure of this review.

RESULTS

Two-hundred and forty-five papers were included in the review. The introductory part was interpreted by 9 papers. Tyrosine kinase inhibitors' role in the inhibition of Pglycoprotein and chemosensitization was illustrated by 87 papers. The contribution of naturalbased compounds in overcoming multidrug resistance was reviewed using 92 papers, while specific dual inhibitors acting against microtubule assembling and/or topoisomerases were described with 55 papers. Eleven papers gave an insight into a novel and less explored approach with hybrid drugs. Their influence on P-glycoprotein and multidrug resistance was also evaluated.

CONCLUSION

These findings bring into focus rational anticancer strategies with dual-targeting agents. Most evaluated synthetic and natural drugs showed a great potential in chemosensitization. Further steps in this direction are needed for the optimization of anticancer treatment.

Synthesis of new triazole linked carbohybrids with ROS-mediated toxicity in breast cancer

Carbohybrids are an important class of molecules which exhibit diverse biological activities. New coumarins and quinolones linked carbohybrids are synthesised which are showing selective anticancer activity.

Quantitative Analysis of Expression Level of BCL2 and BAX Genes in Hep-2 and HL-60 Cells after Treatment with Etoposide

Apoptotic cell death is a highly regulated process, which plays a crucial role in many biological events. The aim of the present research was to investigate the expression of the apoptosis related genes BCL2 and BAX in Hep-2 and HL- 60 cells. Apoptosis was induced in these cell lines during treatment with etoposide. The expression levels of BCL2 and BAX genes were measured after 6 h and 12 h of treatment by quantitative real-time RT-PCR. In Hep-2 cells the expression level of BCL2 significantly increased both 6 h and 12 h of treatment, whereas expression level of BAX didn’t change. In HL-60 cells the expression level of BCL2 decreased after 6 h of treatment and expression of BAX increased both 6 h and 12 h of treatment with etoposide. Those findings show distinct reactions of Hep-2 and HL-60 cells to etoposide treatment and different upregulation or downregulation of apoptosis-related genes BCL2 and BAX.

Identification of gallic acid based glycoconjugates as a novel tubulin polymerization inhibitors

A novel class of gallic acid based glycoconjugates were designed and synthesized as potential anticancer agents. Among all the compounds screened, compound 2a showed potent anticancer activity against breast cancer cells. The latter resulted in tubulin polymerization inhibition and induced G2/M cell cycle arrest, generation of reactive oxygen species, mitochondrial depolarization and subsequent apoptosis in breast cancer cells. In addition, ultraviolet-visible spectroscopy and fluorescence quenching studies of the compound with tubulin confirmed direct interaction of compounds with tubulin. Molecular modeling studies revealed that it binds at the colchicine binding site in tubulin. Further, 2a also exhibited potent in vivo anticancer activity in LA-7 syngeneic rat mammary tumor model. Current data projects its strong candidature to be developed as anticancer agent.

Rhodium(II) Proximity-Labeling Identifies a Novel Target Site on STAT3 for Inhibitors with Potent Anti-Leukemia Activity

Nearly 40 % of children with acute myeloid leukemia (AML) suffer relapse arising from chemoresistance, often involving upregulation of the oncoprotein STAT3 (signal transducer and activator of transcription 3). Herein, rhodium(II)-catalyzed, proximity-driven modification identifies the STAT3 coiled-coil domain (CCD) as a novel ligand-binding site, and we describe a new naphthalene sulfonamide inhibitor that targets the CCD, blocks STAT3 function, and halts its disease-promoting effects in vitro, in tumor growth models, and in a leukemia mouse model, validating this new therapeutic target for resistant AML.

Podophyllotoxin derivatives: a patent review (2012 - 2014)

INTRODUCTION

Podophyllotoxin (PPT) is a naturally occurring antimitotic agent and an interesting lead in the development of anticancer agents. Its optimization led to the development of etoposide and teniposide used in combination chemotherapy with other anticancer drugs; unlike PPT these drugs act by inhibiting topoisomerases. Clinical success and toxicity issues at later stages of etoposide usage inclined researchers to develop structurally modified PPT derivatives. Some of the compounds obtained are under clinical investigations and are anticipated to reach the market.

AREAS COVERED

The present review summarizes the attempts made by researchers across the globe to find out newer anticancer agents based on the PPT structure. It brings out the outline of the inventions filed in the form of patents during the years 2012 - 2014.

EXPERT OPINION

After the successful development of etoposide and teniposide there has been considerable interest in the PPT skeleton to develop newer chemotherapeutic agents. In this regard, several PPT derivatives such as TOP53, GL331, NK611, F11782, and so on, have been developed and are undergoing clinical trials. However, its low natural abundance is a major problem in carrying out research on PPT skeleton. This issue is expected to be addressed with the development of newer synthetic strategies to access structurally modified PPTs.

Analgesic and anti-inflammatory activity of podophyllotoxin derivatives

CONTEXT

Podophyllotoxin is a natural product that inhibits the polymerization of tubulin and has served as a prototype for the development of diverse antitumor agents in clinical use, such as etoposide, teniposide and etopophos. Reumacon, another semisynthetic derivative, reached its clinical phase for the treatment of rheumatoid arthritis.

OBJECTIVE

This study investigated the analgesic and anti-inflammatory properties of three compound derivatives from podophyllotoxin.

MATERIALS AND METHODS

During a phytochemical study performed on Juniperus thurifera Linne (Cupressaceae) leaves, among other products, several cyclolignans, such as podophyllotoxin, deoxypodophyllotoxin, deoxypicropodophyllotoxin and thuriferic acid were isolated. These compounds, obtained afterwards through semisynthesis, were assayed as analgesic and anti-inflammatory agents. Additionally, the cytotoxic activity of thuriferic acid was evaluated in three cancer cell lines, P-388, A-549 and HT-29, and these data were compared with previous cytotoxicity results obtained for the other three compounds.

RESULTS

Analgesic activity results showed that deoxypicropodophyllin is as effective as deoxypodophyllotoxin to inhibit nociceptive perception induced by acetic acid in mice (77.8% ± 4.1% and 71.3% ± 6.5%, respectively), while its cytotoxicity [1.01 × 10(-7) (GI50 M)] is 100-fold less. Other set of experiments showed that thuriferic acid, a derivative of podophyllotoxin a thousand times less citotoxic [1.21 × 10(-5) (GI50 M)] than deoxypodophyllotoxin, caused significant inhibition of paw edema development in the carrageenan-induced inflammation test (63.4% ± 3.3%), effect comparable to those of deoxypodophyllotoxin (66.3% ± 4.4%), and the standard drug indomethacin (61.5% ± 2.5%).

CONCLUSION

We conclude that deoxypicropodophyllotoxin and thuriferic acid are effective in reducing edema formation. However, deoxypicropodophyllin is more related with analgesic activity than anti-inflammatory effect.

3EZ,20Ac-ingenol, a catalytic inhibitor of topoisomerases, downregulates p-Akt and induces DSBs and apoptosis of DT40 cells

We have previously reported that many ingenol compounds derived from Euphorbia kansui exhibit topoisomerase (topo) II inhibitory activity. Of these compounds, 3EZ,20Ac-ingenol inhibited topo I activity. Camptothecin, which inhibits the religation activity of topo I without interfering with the binding of topo I to DNA and induces topo I-mediated DNA cleavage, was used as a positive control. In this study, we found that 3EZ,20Ac-ingenol did not hamper the binding of topo I to DNA in the same manner as camptothecin but affected the inhibition of cleavage of one DNA strand. 3EZ,20Ac-ingenol inhibited cell proliferation by blocking cell cycle progression in the G2/M phase. To define the mechanism of inhibition of DT40 cell proliferation, the change in Akt activity was observed because Akt activity is regulated in response to DNA damage. Western blot analysis revealed that 3EZ,20Ac-ingenol downregulated the expression of p-Akt, and apoptosis was detected by the presence of DNA double-strand breaks and caspase 3 activation.

An integrated Drosophila model system reveals unique properties for F14512, a novel polyamine-containing anticancer drug that targets topoisomerase II

F14512 is a novel anti-tumor molecule based on an epipodophyllotoxin core coupled to a cancer-cell vectoring spermine moiety. This polyamine linkage is assumed to ensure the preferential uptake of F14512 by cancer cells, strong interaction with DNA and potent inhibition of topoisomerase II (Topo II). The antitumor activity of F14512 in human tumor models is significantly higher than that of other epipodophyllotoxins in spite of a lower induction of DNA breakage. Hence, the demonstrated superiority of F14512 over other Topo II poisons might not result solely from its preferential uptake by cancer cells, but could also be due to unique effects on Topo II interactions with DNA. To further dissect the mechanism of action of F14512, we used Drosophila melanogaster mutants whose genetic background leads to an easily scored phenotype that is sensitive to changes in Topo II activity and/or localization. F14512 has antiproliferative properties in Drosophila cells and stabilizes ternary Topo II/DNA cleavable complexes at unique sites located in moderately repeated sequences, suggesting that the drug specifically targets a select and limited subset of genomic sequences. Feeding F14512 to developing mutant Drosophila larvae led to the recovery of flies expressing a striking phenotype, "Eye wide shut," where one eye is replaced by a first thoracic segment. Other recovered F14512-induced gain- and loss-of-function phenotypes similarly correspond to precise genetic dysfunctions. These complex in vivo results obtained in a whole developing organism can be reconciled with known genetic anomalies and constitute a remarkable instance of specific alterations of gene expression by ingestion of a drug. "Drosophila-based anticancer pharmacology" hence reveals unique properties for F14512, demonstrating the usefulness of an assay system that provides a low-cost, rapid and effective complement to mammalian models and permits the elucidation of fundamental mechanisms of action of candidate drugs of therapeutic interest in humans.

Parathyroid hormone suppresses osteoblast apoptosis by augmenting DNA repair

Daily injection of parathyroid hormone (PTH) is a clinically approved treatment for osteoporosis. It suppresses apoptosis of bone-forming osteoblasts although its exact anti-apoptotic mechanism(s) is incompletely understood. In this study, PTH treatment of cultured osteoblasts blocked the pro-apoptotic effects of serum withdrawal and nutrient deprivation; hydrogen peroxide induced oxidative stress, and UV irradiation. We hypothesized that PTH might suppress osteoblast apoptosis by enhancing DNA repair. Evidence is provided showing that post-confluent, non-proliferating osteoblasts treated with PTH exhibited a protein kinase A-mediated activation of two proteins that regulate DNA repair processes (proliferating cell nuclear antigen and forkhead box transcription factor 3a) as well as a suppression of the pro-apoptotic growth arrest and DNA damage protein 153. Additional proof of a connection between DNA damage and osteoblast apoptosis came from an unexpected finding whereby a majority of fixed PTH-treated osteoblasts scored weakly positive for Terminal Deoxynucleotidyl dUTP Nick-End Labeling (TUNEL), even though similar cultures were determined to be viable via a trypsin replating strategy. TUNEL identifies DNA excision repair, not just apoptotic DNA fragmentation, and the most likely explanation of these TUNEL results is that PTH's activation of DNA repair processes would permit nucleotide incorporation as a result of enhanced excision repair. This explanation was confirmed by an enhanced incorporation of bromodeoxyuridine in PTH-treated cells even though a majority of the cell population was determined to be non-replicating. An augmentation of DNA repair by PTH is an unreported finding, and provides an additional explanation for its anti-apoptotic mechanism(s).

Natural products to drugs: natural product-derived compounds in clinical trials

Natural product and natural product-derived compounds that are being evaluated in clinical trials or are in registration (as at 31st December 2007) have been reviewed, as well as natural product-derived compounds for which clinical trials have been halted or discontinued since 2005. Also discussed are natural product-derived drugs launched since 2005, new natural product templates and late-stage development candidates.

Drug discovery and development with plant-derived compounds

An overview is given on current efforts in drug development based on plant-derived natural products. Emphasis is on projects which have advanced to clinical development. Therapeutic areas covered include cancer, viral infections including HIV, malaria, inflammatory diseases, nociception and vaccine adjuvants, metabolic disorders, and neurodegenerative diseases. Aspects which are specific to plant-based drug discovery and development are also addressed, such as supply issues in the commercial development, and the Convention on Biological Diversity.