Recent developments in topoisomerase-targeted cancer chemotherapy

Discovery of Indolo[3,2-c]isoquinoline Derivatives as Novel Top1/2 Dual Inhibitors with Orally Efficacious Antitumor Activity and Low Toxicity

Topoisomerase (Top) inhibitors used in clinical cancer treatments are limited because of their toxicity and severe side effects. Noteworthily, Top1/2 dual inhibitors overcome the compensatory effect between Top1 and 2 inhibitors to exhibit stronger antitumor efficacies. In this study, a series of indolo[3,2-c]isoquinoline derivatives were designed as Top1/2 dual inhibitors possessing apparent antiproliferative activities. Mechanistic studies indicated that the optimal compounds 23 and 31 with increasing reactive oxygen species levels damage DNA, inducing both cancer cell apoptosis and cycle arrest. Importantly, the results of the toxicity studies showed that compounds 23 and 31 possessed good oral safety profiles. In xenograft models, compound 23 exhibited remarkable antitumor potency, which was superior to the clinical Top inhibitors irinotecan and etoposide. Overall, this work highlights the therapeutic potential and safety profile of compound 23 as a Top1/2 dual inhibitor in tumor therapy and provides valuable lead compounds for further development of Top inhibitors.

Use of Drug Sensitisers to Improve Therapeutic Index in Cancer

The clinical management of malignant tumours is challenging, often leading to severe adverse effects and death. Drug resistance (DR) antagonises the effectiveness of treatments, and increasing drug dosage can worsen the therapeutic index (TI). Current efforts to overcome DR predominantly involve the use of drug combinations, including applying multiple anti-cancerous drugs, employing drug sensitisers, which are chemical agents that enhance pharmacokinetics (PK), including the targeting of cellular pathways and regulating pertinent membrane transporters. While combining multiple compounds may lead to drug-drug interactions (DDI) or polypharmacy effect, the use of drug sensitisers permits rapid attainment of effective treatment dosages at the disease site to prevent early DR and minimise side effects and will reduce the chance of DDI as lower drug doses are required. This review highlights the essential use of TI in evaluating drug dosage for cancer treatment and discusses the lack of a unified standard for TI within the field. Commonly used benefit-risk assessment criteria are summarised, and the critical exploration of the current use of TI in the pharmaceutical industrial sector is included. Specifically, this review leads to the discussion of drug sensitisers to facilitate improved ratios of effective dose to toxic dose directly in humans. The combination of drug and sensitiser molecules might see additional benefits to rekindle those drugs that failed late-stage clinical trials by the removal of detrimental off-target activities through the use of lower drug doses. Drug combinations and employing drug sensitisers are potential means to combat DR. The evolution of drug combinations and polypharmacy on TI are reviewed. Notably, the novel binary weapon approach is introduced as a new opportunity to improve TI. This review emphasises the urgent need for a criterion to systematically evaluate drug safety and efficiency for practical implementation in the field.

Two-Phase Electrosynthesis of Dihydroxycoumestans: Discovery of a New Scaffold for Topoisomerase I Poison

Coumestan represents a biologically relevant structural motif distributed in a number of natural products, and the rapid construction of related derivatives as well as the characterization of targets would accelerate lead compound discovery in medicinal chemistry. In this work, a general and scalable approach to 8,9-dihydroxycoumestans via two-electrode constant current electrolysis was developed. The application of a two-phase (aqueous/organic) system plays a crucial role for success, protecting the sensitive o-benzoquinone intermediates from over-oxidation. Based on the structurally diverse products, a primary SAR study on coumestan scaffold was completed, and compound 3 r exhibited potent antiproliferative activities and a robust topoisomerase I (Top1) inhibitory activity. Further mechanism studies demonstrates that compound 3 r was a novel Top1 poison, which might open an avenue for the development of Top1-targeted antitumor agent.

In vitro study on the anticancer effects of oxalipalladium against PC3 human prostate carcinoma cells

Prostate cancer is a common type of cancer in men with high incidence and mortality. Our aim was to investigate the effects of oxalipalladium (ox-Pd) on metastatic human prostate cancer PC3 cells and compare them with the effects of oxaliplatin (ox-Pt) (as an approved cancer drug). We synthesized ox-Pd through a new chemical method and used FT-IR, 1H NMR, 13C NMR, and MS analyzes to characterize it. The effects of ox-Pd on PC3 cells viability, apoptosis, cell cycle, migration, and gene expression were examined. Inhibition of topoisomerase IIα activity was investigated by pHOT1 plasmid relaxation and kDNA decatenation assays. Chemical tests showed ox-Pd with the correct composition and structure. For the first time, the exact fragmentation pathway of ox-Pd and its difference with ox-Pt was obtained by MS analysis. Ox-Pd significantly decreased PC3 cell viability with less/no toxicity effect on MHFB-1 normal skin fibroblasts. Wound scratch assay confirmed the strong anti-migratory activity of ox-Pd. According to flow cytometry analysis, this drug increased the number of PC3 cells in late apoptosis and decreased DNA replication and mitosis. Furthermore, pHOT1 plasmid relaxation and kDNA decatenation assays showed that ox-Pd strongly inhibited the catalytic activity of topoisomerase IIα. The expression of topoisomerase IIα, Bcl-2, P21, and survivin was decreased while the expression of Bax and p53 was increased under ox-Pd treatment. We provide the first evidence that ox-Pd exhibits more selective anticancer effects on PC3 cells compared to ox-Pt. Taken together, these data strongly suggest a therapeutic window for ox-Pd in cancer.

Anticancer mechanism of coumarin-based derivatives

The structural motif of coumarins is related with various biological activities and pharmacological properties. Both natural coumarin extracted from various plants or a new coumarin derivative synthesized by modification of the basic structure of coumarin, in vitro experiments showed that coumarins are a promising class of anti-tumor agents with high selectivity. Cancer is a complex and multifaceted group of diseases characterized by the uncontrolled and abnormal growth of cells in the body. This review focuses on the anticancer mechanism of various coumarins synthesized and isolated in more than a decade. Isopentenyloxycoumarins inhibit angiogenesis by reducing CCl2 chemokine levels. Ferulin C is a potent colchicine-binding agent that destabilizes microtubules, exhibiting antiproliferative and anti-metastatic effects in breast cancer cells through PAK1 and PAK2-mediated signaling. Trimers of triphenylethylene-coumarin hybrids demonstrated significant proliferation inhibition in HeLa, A549, K562, and MCF-7 cell lines. Platinum(IV) complexes with 4-hydroxycoumarin have the potential for high genotoxicity against tumor cells, inducing apoptosis in SKOV-3 cells by up-regulating caspase 3 and caspase 9 expression. Derivatives of 3-benzyl coumarin seco-B-ring induce apoptosis, mediated through the PI3K/Akt/mTOR signaling pathway. Sesquiterpene coumarins inhibit the efflux pump of multidrug resistance-associated protein. Coumarin imidazolyl derivatives inhibit the aromatase enzyme, a major contributor to estrogen overproduction in estrogen-dependent breast cancer.

Molecular regulation of the key specialized metabolism pathways in medicinal plants

The basis of modern pharmacology is the human ability to exploit the production of specialized metabolites from medical plants, for example, terpenoids, alkaloids, and phenolic acids. However, in most cases, the availability of these valuable compounds is limited by cellular or organelle barriers or spatio-temporal accumulation patterns within different plant tissues. Transcription factors (TFs) regulate biosynthesis of these specialized metabolites by tightly controlling the expression of biosynthetic genes. Cutting-edge technologies and/or combining multiple strategies and approaches have been applied to elucidate the role of TFs. In this review, we focus on recent progress in the transcription regulation mechanism of representative high-value products and describe the transcriptional regulatory network, and future perspectives are discussed, which will help develop high-yield plant resources.

Design, synthesis, and biological evaluation of harmine derivatives as topoisomerase I inhibitors for cancer treatment

A series of β-carboline derivatives were designed and synthesized by introducing the chalcone moiety into the harmine. The synthesized derivatives were evaluated their anti-proliferative activities against six human cancer cell lines (MCF-7, MDA-MB-231, HepG2, HT29, A549, and PC-3) and one normal cell line (L02). Among them, compound G11 exhibited the potent anti-proliferative activity against MCF-7 cell line, with an IC50 value of 0.34 μM. Further biological studies revealed that compound G11 inhibited colony formation of MCF-7 cells, suppressed MCF-7 cell migration by downregulating migration-associated protein MMP-2. In addition, it could induce apoptosis of MCF-7 cells by downregulating Bcl-2 and upregulating Cleaved-PARP, Bax, and phosphorylated Bim proteins. Furthermore, compound G11 can act as a Topo I inhibitor, affecting DNA synthesis and transcription, thereby inhibiting cancer cell proliferation. Moreover, compound G11 inhibited tumor growth in 4T1 syngeneic transplant mice with an inhibition rate of 43.19 % at a dose of 10 mg/kg, and 63.87 % at 20 mg/kg, without causing significant toxicity to the mice or their organs, achieving the goal of reduced toxicity and increased efficacy. All these results indicate of G11 has enormous potential as an anti-tumor agent and merits further investigation.

Camptothecin structure simplification elaborated new imidazo[2,1-b]quinazoline derivative as a human topoisomerase I inhibitor with efficacy against bone cancer cells and colon adenocarcinoma

Camptothecin is a pentacyclic natural alkaloid that inhibits the hTop1 enzyme involved in DNA transcription and cancer cell growth. Camptothecin structure pitfalls prompted us to design new congeners using a structure simplification strategy to reduce the ring extension number from pentacyclic to tetracyclic while maintaining potential stacking of the new compounds with the DNA base pairs at the Top1-mediated cleavage complex and aqueous solubility, as well as minimizing compound-liver toxicity. The principal axis of this study was the verification of hTop1 inhibiting activity as a possible mechanism of action and the elaboration of new simplified inhibitors with improved pharmacodynamic and pharmacokinetic profiling using three structure panels (A-C) of (isoquinolinoimidazoquinazoline), (imidazoquinazoline), and (imidazoisoquinoline), respectively. DNA relaxation assay identified five compounds as hTop1 inhibitors belonging to the imidazoisoquinolines 3a,b, the imidazoquinazolines 12, and the isoquinolinoimidazoquinazolines 7a,b. In an MTT cytotoxicity assay against different cancer cell lines, compound 12 was the most potent against HOS bone cancer cells (IC50 = 1.47 μM). At the same time, the other inhibitors had no detectable activity against any cancer cell type. Compound (12) demonstrated great penetrating power in the HOS cancer cells' 3D-multicellular tumor spheroid model. Bioinformatics research of the hTop1 gene revealed that the TP53 cell proliferative gene is in the network of hTop1. The finding is confirmed empirically using the gene expression assay that proved the increase in p53 expression. The impact of structure simplification on compound 12 profile, characterized by the absence of acute oral liver toxicity when compared to Doxorubicin as a standard inhibitor, the lethal dose measured on Swiss Albino female mice and reported at LD50 = 250 mg/kg, and therapeutic significance in reducing colon adenocarcinoma tumor volume by 75.36 % after five weeks of treatment with compound 12. The molecular docking solutions of the active CPT-based derivative 12 and the inactive congener 14 into the active site of hTop1 and the activity cliffing of such MMP directed us to recommend the addition of HBD and HBA variables to compound 12 imidazoquinazoline core scaffold to enhance the potency via hydrogen bond formation with the major groove amino acids (Asp533, Lys532) as well as maintaining the hydrogen bond with the minor groove amino acid Arg364.

Unraveling the Molecular Complexity of Adenoid Cystic Carcinoma (ACC): A Comprehensive Exploration of Hub Genes, Protein-Protein Interaction (PPI) Networks, microRNA (miRNA) Involvement, and Drug-Gene Interactions (DGIs)

Background Adenoid cystic carcinoma (ACC) poses clinical challenges with its unique histology and potential for perineural invasion, recurrence, and distant metastases. Recent genomic advancements have unveiled key genetic alterations in ACC, offering insights into its pathogenesis. Aim This study aims to unravel the intricate molecular landscape of ACC through a comprehensive analysis of gene expression patterns. By integrating data from multiple microarray datasets, the study explores differentially expressed genes (DEGs), their functional enrichment, protein-protein interactions (PPI), hub genes, microRNA (miRNA) involvement, transcription factors, and potential drug-gene interactions. Methods Three microarray datasets (GSE88804, GSE153002, and GSE36820) related to ACC were selected from the Gene Expression Omnibus (GEO) repository. DEGs were identified using GEO2R and further analyzed for commonalities and differences. Functional enrichment analysis, including Gene Set Enrichment Analysis (GSEA), provided insights into biological processes, cellular components, molecular functions, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with ACC. PPI networks and hub genes were identified using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) (STRING Consortium, Lausanne, Switzerland) database and Cytoscape (Cytoscape Consortium, California, United States). The study also explored miRNAs, transcription factors, and potential drug-gene interactions. Results The integrated analysis revealed 339 common upregulated and 643 downregulated DEGs in ACC. Functional and pathway enrichment analyses unveiled the involvement of these genes in critical cellular processes, signaling cascades, and pathways. The PPI network, comprising 904 nodes and 4139 edges, highlighted the complexity of interactions. Hub genes, including KIF11, BUB1, and DLGAP5, were identified, shedding light on their pivotal roles in cell cycle regulation. The study also identified miRNAs (e.g., hsa-mir-7-5p and hsa-mir-138-5p) and transcription factors (e.g., E2F1 and TP53) associated with ACC. Drug-gene interactions have identified potential therapeutic options, including amsacrine and rucaparib. Conclusions The ACC gene expression highlights a nuanced molecular landscape, identifying pivotal hub genes such as KIF11 and CDK1 as potential therapeutic targets for ACC, given their roles in cell cycle progression. The dysregulation of microRNAs and transcription factors adds complexity to ACC's molecular profile. Exploration of drug-gene interactions reveals promising therapeutic strategies, involving FDA-approved drugs such as amsacrine and rucaparib, providing avenues for personalized interventions.

Design and synthesis of luotonin A-derived topoisomerase targeting scaffold with potent antitumor effect and low genotoxicity

Conventional topoisomerase (Topo) inhibitors typically usually exert their cytotoxicity by damaging the DNAs, which exhibit high toxicity and tend to result in secondary carcinogenesis risk. Molecules that have potent topoisomerase inhibitory activity but involve less DNA damage provide more desirable scaffolds for developing novel chemotherapeutic agents. In this work, we broke the rigid pentacyclic system of luotonin A and synthesized thirty-three compounds as potential Topo inhibitors based on the devised molecular motif. Further investigation disclose that two compounds with the highest antiproliferation activity against cancer cells, 5aA and 5dD, had a distinct Topo I inhibitory mechanism different from those of the classic Topo I inhibitors CPT or luteolin, and were able to obviate the obvious cellular DNA damage typically associated with clinically available Topo inhibitors. The animal model experiments demonstrated that even in mice treated with a high dosage of 50 mg/kg 5aA, there were no obvious signs of toxicity or loss of body weight. The tumor growth inhibition (TGI) rate was 54.3 % when 20 mg/kg 5aA was given to the T24 xenograft mouse model, and 5aA targeted the cancer tissue precisely without causing damage to the liver and other major organs.

MDM2 provides TOP2 poison resistance by promoting proteolysis of TOP2βcc in a p53-independent manner

DNA topoisomerase II (TOP2) is an enzyme that performs a critical function in manipulating DNA topology during replication, transcription, and chromosomal compaction by forming a vital intermediate known as the TOP2-DNA cleavage complex (TOP2cc). Although the TOP2cc is often transient, stabilization can be achieved by TOP2 poisons, a family of anti-cancer chemotherapeutic agents targeting TOP2, such as etoposide (VP-16), and then induce double-strand breaks (DSBs) in cellular DNA. TOP2cc first needs to be proteolyzed before it can be processed by TDP2 for the removal of these protein adducts and to produce clean DNA ends necessary for proper repair. However, the mechanism by which TOP2βcc is proteolyzed has not been thoroughly studied. In this study, we report that after exposure to VP-16, MDM2, a RING-type E3 ubiquitin ligase, attaches to TOP2β and initiates polyubiquitination and proteasomal degradation. Mechanistically, during exposure to VP-16, TOP2β binds to DNA to form TOP2βcc, which promotes MDM2 binding and subsequent TOP2β ubiquitination and degradation, and results in a decrease in TOP2βcc levels. Biologically, MDM2 inactivation abrogates TOP2β degradation, stabilizes TOP2βcc, and subsequently increases the number of TOP2β-concealed DSBs, resulting in the rapid death of cancer cells via the apoptotic process. Furthermore, we demonstrate the combination activity of VP-16 and RG7112, an MDM2 inhibitor, in the xenograft tumor model and in situ lung cancer mouse model. Taken together, the results of our research reveal an underlying mechanism by which MDM2 promotes cancer cell survival in the presence of TOP2 poisons by activating proteolysis of TOP2βcc in a p53-independent manner, and provides a rationale for the combination of MDM2 inhibitors with TOP2 poisons for cancer therapy.

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

DNA topoisomerases as a drug target in Leishmaniasis: Structural and mechanistic insights

Leishmaniasis, caused by a protozoan parasite, is among humanity's costliest banes, owing to the high mortality and morbidity ratio in poverty-stricken areas. To date, no vaccine is available for the complete cure of the disease. Current chemotherapy is expensive, has undesirable side effects, and faces drug resistance limitations and toxicity concerns. The substantial differences in homology between leishmanial DNA topoisomerase IB compared with the human counterparts provided a new lead in the study of the structural determinants that can be targeted. Several research groups explored this molecular target, trying to fill the therapeutic gap, and came forward with various anti-leishmanial scaffolds. This article is a comprehensive review of knowledge about topoisomerases as an anti-leishmanial drug target and their inhibitors collected over the years. In addition to information on molecular targets and reported scaffolds, the review details the structure-activity relationship of described compounds with leishmanial Topoisomerase IB. Moreover, the work also includes information about the structure of the inhibitors, showing common interacting residues with leishmanial topoisomerases that drive their mode of action towards them. Finally, in search of topoisomerase inhibitors at the stage of clinical trials, we have listed all the drugs that have been in clinical trials against leishmaniasis.

Novel N-(3-ethynyl Phenyl)-6,7-bis(2-methoxyethoxy)Quinazoline-4-amine Derivatives: Synthesis, Characterization, Anti-cancer Activity, In-silico and DFT Studies

BACKGROUND

Cancer is one of the most common reasons for mortality in the world. A continuous effort to develop effective anti-cancer drugs with minimum side effects has become necessary. The use of small-molecule drugs has revolutionized cancer research by inhibiting cancer cell survival and proliferation. Quinazolines are a class of bioactive heterocyclic compounds with active pharmacophores in several anti-cancer drugs. Such small molecule inhibitors obstruct the significant signals responsible for cancer cell development, thus blocking these cell signals to prevent cancer development and spread.

OBJECTIVE

In the current study, novel quinazoline derivatives structurally similar to erlotinib were synthesized and explored as novel anti-cancer agents.

METHODS

All the synthesized molecules were confirmed by spectroscopic techniques like 1H NMR, 13C NMR, and ESI-MS. Various techniques were applied to study the protein-drug interaction, DFT analysis, Hirshfeld surface, and target prediction. The molecules were screened in vitro for their anti-cancer properties against 60 human tumor cell lines. The growth inhibitory properties of a few compounds were studied against the MCF7 breast cancer cell line.

RESULTS

The activity of compounds 9f, 9o, and 9s were found to be active. However, compound 9f is more active when compared with other compounds.

CONCLUSION

Some synthesized compounds were active against different cancer cell lines. The in-vitro study results were found to be in agreement with the predictions from in-silico data. The selected molecules were further subjected to get the possible mechanism of action against different cancer cells.

Biotransformation of Ursonic Acid by Aspergillus ochraceus and Aspergillus oryzae to Discover Anti-Neuroinflammatory Derivatives

Biotransformation of ursonic acid (1) by two fungal strains Aspergillus ochraceus CGMCC 3.5324 and Aspergillus oryzae CGMCC 3.407 yielded thirteen new compounds (4, 5, 7-10, and 13-19), along with five recognized ones. The structural details of new compounds were determined through spectroscopic examination (NMR, IR, and HR-MS) and X-ray crystallography. Various modifications, including hydroxylation, epoxidation, lactonization, oxygen introduction, and transmethylation, were identified on the ursane core. Additionally, the anti-neuroinflammatory efficacy of these derivatives was assessed on BV-2 cells affected by lipopolysaccharides. It was observed that certain methoxylated and epoxylated derivatives (10, 16, and 19) showcased enhanced suppressive capabilities, boasting IC50 values of 8.2, 6.9, and 5.3 μM. Such ursonic acid derivatives might emerge as potential primary molecules in addressing neurodegenerative diseases.

Dual-target inhibitors based on COX-2: a review from medicinal chemistry perspectives

Inhibitors of COX-2 constitute a class of anti-inflammatory analgesics, showing potential against certain types of cancer. However, such inhibitors are associated with cardiovascular toxicity. Moreover, although single-target molecules possess specificity for particular targets, they often lead to poor safety, low efficacy and drug resistance due to compensatory mechanisms. A new generation of dual-target drugs that simultaneously inhibit COX-2 and another target is showing strong potential to treat cancer or reduce adverse cardiac effects. The present perspective focuses on the structure and functions of COX-2, and its role as a therapeutic target. It also explores the current state and future possibilities for dual-target strategies from a medicinal chemistry perspective.

Current Role of Topoisomerase I Inhibitors for the Treatment of Mesenchymal Malignancies and Their Potential Future Use as Payload of Sarcoma-Specific Antibody-Drug Conjugates

BACKGROUND

Topoisomerase I is an enzyme that plays a crucial part in DNA replication and transcription by the relaxation of supercoiled double-stranded DNA. Topoisomerase I inhibitors bind to the topoisomerase I cleavage complex, thereby stabilizing it and preventing the religation of the DNA strands, leading to DNA damage, cell cycle arrest, and apoptosis. Various topoisomerase I inhibitors have been evaluated in solid tumors, and irinotecan and topotecan have been approved for the treatment of epithelial malignancies. None of them have been approved for sarcoma, a diverse group of rare solid tumors with an unmet need for effective treatments.

SUMMARY

Topoisomerase I inhibitors have been evaluated in preclinical studies as single agents or in combination in solid tumors, some of which have included sarcomas where activity was observed. Clinical trials evaluating topoisomerase I inhibitors for the treatment of sarcoma have shown limited efficacy as monotherapy. In combination with other cytotoxic agents, topoisomerase I inhibitors have become part of clinical routine in selected sarcoma subtypes. Regimens such as irinotecan/vincristine/temozolomide are used in relapsed rhabdomyosarcoma, irinotecan/temozolomide and vincristine/topotecan/cyclophosphamide are commonly given in refractory Ewing sarcoma, and topotecan/carboplatin showed some activity in advanced soft tissue sarcoma. This review provides an overview of key studies with topoisomerase I inhibitors for the treatment of sarcoma. Topoisomerase I inhibitors are currently also being assessed as "payloads" for antibody-drug conjugates (ADCs), allowing for the targeting of specific antigen-expressing tumor cells and the delivery of the inhibitor directly to the tumor cells with the potential of enhancing therapeutic efficacy while minimizing systemic toxicity. Here, we also provide a brief overview on topoisomerase I-ADCs.

KEY MESSAGE

Topoisomerase I inhibitors are an important component of some systemic therapies for selected sarcomas and have potent cytotoxic properties and pharmacological characteristics that make them relevant candidates as payloads for the development of sarcoma-specific ADCs. ADCs are antibody-based targeted agents allowing for efficient and specific delivery of a given drug to the tumor cell. Topoisomerase I-ADCs are a novel targeted delivery approach which may have the potential to improve the therapeutic index of topoisomerase I inhibitors in the treatment of sarcoma and warrants investigation in a broad variety of mesenchymal malignancies.

A CircRNA-miRNA-mRNA Network for Exploring Doxorubicin- and Myocet-Induced Cardiotoxicity in a Translational Porcine Model

Despite the widespread use of doxorubicin (DOX) as a chemotherapeutic agent, its severe cumulative cardiotoxicity represents a significant limitation. While the liposomal encapsulation of doxorubicin (Myocet, MYO) reduces cardiotoxicity, it is crucial to understand the molecular background of doxorubicin-induced cardiotoxicity. Here, we examined circular RNA expression in a translational model of pigs treated with either DOX or MYO and its potential impact on the global gene expression pattern in the myocardium. This study furthers our knowledge about the regulatory network of circRNA/miRNA/mRNA and its interaction with chemotherapeutics. Domestic pigs were treated with three cycles of anthracycline drugs (DOX, n = 5; MYO, n = 5) to induce cardiotoxicity. Untreated animals served as controls (control, n = 3). We applied a bulk mRNA-seq approach and the CIRIquant algorithm to identify circRNAs. The most differentially regulated circRNAs were validated under cell culture conditions, following forecasting of the circRNA-miRNA-mRNA network. We identified eight novel significantly regulated circRNAs from exonic and mitochondrial regions in the porcine myocardium. The forecasted circRNA-miRNA-mRNA network suggested candidate circRNAs that sponge miR-17, miR-15b, miR-130b, the let-7 family, and miR125, together with their mRNA targets. The identified circRNA-miRNA-mRNA network provides an updated, coherent view of the mechanisms involved in anthracycline-induced cardiotoxicity.

In Silico Study of a Small Bioactive Molecule Targeting Topoisomerase II and P53-MDM2 Complex in Triple-Negative Breast Cancer

Treatment of triple-negative breast cancer (TNBC) is very challenging as only few therapeutic options are available, including chemotherapy. Thus, a constant search for new and effective approaches of therapy that could potentially fight against TNBC and mitigate side effects is "turn-on". Recently, multitarget therapy has come up with huge possibilities, and it may possibly be useful to overcome several concurrent challenges in cancer therapy. Herein, we proposed the inhibition of both Topoisomerase II enzyme and p53-MDM2 (p53 cavity in MDM2) protein complex by the same bioactive molecules for multitarget therapy. RNA-seq analysis was performed to get a network of essential proteins involved in the apoptosis pathway by considering the triple-negative breast cancer cell line (MDA-MB-231). All of the untreated duplicate sample data were retrieved from NCBI (GSC149768). Further, via in silico screening, potent bioactive molecules were screened out to target both Topo II and the p53-MDM2 complex. The results of ligand-based screening involving docking, MMGBSA, ADME/T, MD simulation, and PCA suggested that resveratrol, a plant bioactive molecule, showed more potential binding in the same cavity of target proteins compared with doxorubicin for Topo IIα (5GWK) and etoposide for the second protein target (p53-MDM2 complex; 4OQ3) as the control drug. This is also evident from the in vitro validation in case of triple-negative breast cancer cell lines (MDA-MB-231) and Western blotting analysis. Thus, it paves the scope of multitargeting against triple-negative breast cancer.

Prospects of Topoisomerase Inhibitors as Promising Anti-Cancer Agents

Topoisomerases are very important enzymes that regulate DNA topology and are vital for biological actions like DNA replication, transcription, and repair. The emergence and spread of cancer has been intimately associated with topoisomerase dysregulation. Topoisomerase inhibitors have consequently become potential anti-cancer medications because of their ability to obstruct the normal function of these enzymes, which leads to DNA damage and subsequently causes cell death. This review emphasizes the importance of topoisomerase inhibitors as marketed, clinical and preclinical anti-cancer medications. In the present review, various types of topoisomerase inhibitors and their mechanisms of action have been discussed. Topoisomerase I inhibitors, which include irinotecan and topotecan, are agents that interact with the DNA-topoisomerase I complex and avert resealing of the DNA. The accretion of DNA breaks leads to the inhibition of DNA replication and cell death. On the other hand, topoisomerase II inhibitors like etoposide and teniposide, function by cleaving the DNA-topoisomerase II complex thereby effectively impeding the release of double-strand DNA breaks. Moreover, the recent advances in exploring the therapeutic efficacy, toxicity, and MDR (multidrug resistance) issues of new topoisomerase inhibitors have been reviewed in the present review.

Discovery and development of botanical natural products and their analogues as therapeutics for ovarian cancer

Covering: 2015 through the end of July 2022Ovarian cancer is one of the most common cancers affecting the female reproductive organs and has the highest mortality rate among gynecological cancers. Although botanical drugs and their derivatives, namely members of the taxane and camptothecin families, represent significant therapeutics currently available for the treatment of ovarian cancer, new drugs that have alternative mechanisms of action are still needed to combat the disease. For this reason, many efforts to identify additional novel compounds from botanical sources, along with the further development of existing therapeutics, have continued to appear in the literature. This review is designed to serve as a comprehensive look at both the currently available small-molecule therapeutic options and the recently reported botanically-derived natural products currently being studied and developed as potential future therapeutics that could one day be used against ovarian cancer. Specifically, key properties, structural features, and biological data are highlighted that are important for the successful development of potential agents. Recently reported examples are specifically discussed in the context of "drug discovery attributes," including the presence of structure-activity relationship, mechanism of action, toxicity, and pharmacokinetic studies, to help indicate the potential for future development and to highlight where these compounds currently exist in the development process. The lessons learned from both the successful development of the taxanes and camptothecins, as well as the strategies currently being employed for new drug development, are expected to ultimately help guide the future development of botanical natural products for ovarian cancer.

O-GlcNAcylation promotes topoisomerase IIα catalytic activity in breast cancer chemoresistance

DNA topoisomerase IIα (TOP2A) plays a vital role in replication and cell division by catalytically altering DNA topology. It is a prominent target for anticancer drugs, but clinical efficacy is often compromised due to chemoresistance. In this study, we investigate the role of TOP2A O-GlcNAcylation in breast cancer cells and patient tumor tissues. Our results demonstrate that elevated TOP2A, especially its O-GlcNAcylation, promotes breast cancer malignant progression and resistance to adriamycin (Adm). O-GlcNAcylation at Ser1469 enhances TOP2A chromatin DNA binding and catalytic activity, leading to resistance to Adm in breast cancer cells and xenograft models. Mechanistically, O-GlcNAcylation-modulated interactions between TOP2A and cell cycle regulators influence downstream gene expression and contribute to breast cancer drug resistance. These results reveal a previously unrecognized mechanistic role for TOP2A O-GlcNAcylation in breast cancer chemotherapy resistance and provide support for targeting TOP2A O-GlcNAcylation in cancer therapy.

β-Lapachone Exerts Anticancer Effects by Downregulating p53, Lys-Acetylated Proteins, TrkA, p38 MAPK, SOD1, Caspase-2, CD44 and NPM in Oxaliplatin-Resistant HCT116 Colorectal Cancer Cells

β-lapachone (β-Lap), a topoisomerase inhibitor, is a naturally occurring ortho-naphthoquinone phytochemical and is involved in drug resistance mechanisms. Oxaliplatin (OxPt) is a commonly used chemotherapeutic drug for metastatic colorectal cancer, and OxPt-induced drug resistance remains to be solved to increase chances of successful therapy. To reveal the novel role of β-Lap associated with OxPt resistance, 5 μM OxPt-resistant HCT116 cells (HCT116-OxPt-R) were generated and characterized via hematoxylin staining, a CCK-8 assay and Western blot analysis. HCT116-OxPt-R cells were shown to have OxPt-specific resistance, increased aggresomes, upregulated p53 and downregulated caspase-9 and XIAP. Through signaling explorer antibody array, nucleophosmin (NPM), CD37, Nkx-2.5, SOD1, H2B, calreticulin, p38 MAPK, caspase-2, cadherin-9, MMP23B, ACOT2, Lys-acetylated proteins, COL3A1, TrkA, MPS-1, CD44, ITGA5, claudin-3, parkin and ACTG2 were identified as OxPt-R-related proteins due to a more than two-fold alteration in protein status. Gene ontology analysis suggested that TrkA, Nkx-2.5 and SOD1 were related to certain aggresomes produced in HCT116-OxPt-R cells. Moreover, β-Lap exerted more cytotoxicity and morphological changes in HCT116-OxPt-R cells than in HCT116 cells through the downregulation of p53, Lys-acetylated proteins, TrkA, p38 MAPK, SOD1, caspase-2, CD44 and NPM. Our results indicate that β-Lap could be used as an alternative drug to overcome the upregulated p53-containing OxPt-R caused by various OxPt-containing chemotherapies.

Diffusion of knots in nanochannel-confined DNA molecules

We used Langevin dynamics simulations without hydrodynamic interactions to probe knot diffusion mechanisms and the time scales governing the evolution and the spontaneous untying of trefoil knots in nanochannel-confined DNA molecules in the extended de Gennes regime. The knot untying follows an "opening up process," wherein the initially tight knot continues growing and fluctuating in size as it moves toward the end of the DNA molecule before its annihilation at the chain end. The mean knot size increases significantly and sub-linearly with increasing chain contour length. The knot diffusion in nanochannel-confined DNA molecules is subdiffusive, with the unknotting time scaling with chain contour length with an exponent of 2.64 ± 0.23 to within a 95% confidence interval. The scaling exponent for the mean unknotting time vs chain contour length, along with visual inspection of the knot conformations, suggests that the knot diffusion mechanism is a combination of self-reptation and knot region breathing for the simulated parameters.

Induction of Immune Responses and Phosphatidylserine Exposure by TLR9 Activation Results in a Cooperative Antitumor Effect with a Phosphatidylserine-targeting Prodrug

Head and neck cancer is a major cancer type, with high motility rates that reduce the quality of life of patients. Herein, we investigated the effectiveness and mechanism of a combination therapy involving TLR9 activator (CpG-2722) and phosphatidylserine (PS)-targeting prodrug of SN38 (BPRDP056) in a syngeneic orthotopic head and neck cancer animal model. The results showed a cooperative antitumor effect of CpG-2722 and BPRDP056 owing to their distinct and complementary antitumor functions. CpG-2722 induced antitumor immune responses, including dendritic cell maturation, cytokine production, and immune cell accumulation in tumors, whereas BPRDP056 directly exerted cytotoxicity toward cancer cells. We also discovered a novel function and mechanism of TLR9 activation, which increased PS exposure on cancer cells, thereby attracting more BPRDP056 to the tumor site for cancer cell killing. Killed cells expose more PS in tumor for BPRDP056 targeting. Tumor antigens released from the dead cells were taken up by antigen-presenting cells, which enhanced the CpG-272-promoted T cell-mediated tumor-killing effect. These form a positive feed-forward antitumor effect between the actions of CpG-2722 and BPRDP056. Thus, the study findings suggest a novel strategy of utilizing the PS-inducing function of TLR9 agonists to develop combinational cancer treatments using PS-targeting drugs.

Recent Developments in Combination Chemotherapy for Colorectal and Breast Cancers with Topoisomerase Inhibitors

DNA topoisomerases are important enzymes that stabilize DNA supercoiling and resolve entanglements. There are two main types of topoisomerases in all cells: type I, which causes single-stranded DNA breaks, and type II, which cuts double-stranded DNA. Topoisomerase activity is particularly increased in rapidly dividing cells, such as cancer cells. Topoisomerase inhibitors have been an effective chemotherapeutic option for the treatment of several cancers. In addition, combination cancer therapy with topoisomerase inhibitors may increase therapeutic efficacy and decrease resistance or side effects. Topoisomerase inhibitors are currently being used worldwide, including in the United States, and clinical trials on the combination of topoisomerase inhibitors with other drugs are currently underway. The primary objective of this review was to comprehensively analyze the current clinical landscape concerning the combined application of irinotecan, an extensively investigated type I topoisomerase inhibitor for colorectal cancer, and doxorubicin, an extensively researched type II topoisomerase inhibitor for breast cancer, while presenting a novel approach for cancer therapy.

Toosendanin targeting eEF2 impedes Topoisomerase I & II protein translation to suppress esophageal squamous cell carcinoma growth

BACKGROUND

Although molecular targets such as HER2, TP53 and PIK3CA have been widely studied in esophageal cancer, few of them were successfully applied for clinical treatment. Therefore, it is urgent to discover novel actionable targets and inhibitors. Eukaryotic translational elongation factor 2 (eEF2) is reported to be highly expressed in various cancers. However, its contribution to the maintenance and progression of cancer has not been fully clarified.

METHODS

In the present study, we utilized tissue array to evaluate eEF2 protein expression and clinical significance in esophageal squamous cell carcinoma (ESCC). Next, we performed knockdown, overexpression, RNA-binding protein immunoprecipitation (RIP) sequence, and nascent protein synthesis assays to explore the molecular function of eEF2. Furthermore, we utilized compound screening, Surface Plasmon Resonance (SPR), Isothermal Titration Calorimetry (ITC) assay, cell proliferation and Patient derived xenograft (PDX) mouse model assays to discover an eEF2 inhibitor and assess its effects on ESCC growth.

RESULTS

We found that eEF2 were highly expressed in ESCC and negatively associated with the prognosis of ESCC patients. Knocking down of eEF2 suppressed the cell proliferation and colony formation of ESCC. eEF2 bond with the mRNA of Topoisomerase II (TOP1) and Topoisomerase II (TOP2) and enhanced the protein biosynthesis of TOP1 and TOP2. We also identified Toosendanin was a novel inhibitor of eEF2 and Toosendanin inhibited the growth of ESCC in vitro and in vivo.

CONCLUSIONS

Our findings show that Toosendanin treatment suppresses ESCC growth through targeting eEF2 and regulating downstream TOP1 and TOP2 biosynthesis. eEF2 could be supplied as a potential therapeutic target in the further clinical studies.

Topoisomerase II inhibitors design: Early studies and new perspectives

The DNA topoisomerase enzymes are widely distributed throughout all spheres of life and are necessary for cell function. Numerous antibacterial and cancer chemotherapeutic drugs target the various topoisomerase enzymes because of their roles in maintaining DNA topology during DNA replication and transcription. Agents derived from natural products, like anthracyclines, epipodophyllotoxins and quinolones, have been widely used to treat a variety of cancers. A very active field of fundamental and clinical research is the selective targeting of topoisomerase II enzymes for cancer treatment. This thematic review summarizes the recent advances in the anticancer activity of the most potent topoisomerase II inhibitors (anthracyclines, epipodophyllotoxins and fluoroquinolones) their modes of action, and structure-activity relationships (SARs) organized chronologically in the last ten years from 2013 to 2023. The review also highlights the mechanism of action and SARs of promising new topoisomerase II inhibitors.

Antitumor copper(II) complexes with hydroxyanthraquinones and N,N-heterocyclic ligands

Five ternary copper(II) complexes, [Cu₂(phen)₂(L1)(ClO₄)₂] (1), [Cu₂(phen)₂(L1)(DMSO)₂](PF6)₂ (2), [Cu₂(bpy)₂(L1)(ClO₄)₂(H₂O)₂] (3), [Cu₂(dmp)₂(L1)(ClO₄)₂(H₂O)₂] (4), and [Cu(phen)(L2)]₂(ClO₄)₂ (5), in which phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine, dmp = 2,9-dimethyl-1,10-phenanthroline, H₂L1 = 1,4-dihydroxyanthracene-9,10-dione and HL2 = 1-hydroxyanthracene-9,10-dione, DMSO = dimethylsulfoxide, were synthesized and fully characterized. Complex 2 was obtained through the substitution of perchlorate for DMSO. When two hydroxyquinone groups are present, L1 makes a bridge between two Cu(II) ions, which also bind two nitrogens of the respective diimine ligand. The compounds bind to calf thymus DNA and oxidatively cleave pUC19 DNA according to the following order of activity 1 > 4-5 > 3. Furthermore, complexes 1, 3, 4 and 5 inhibit topoisomerase-I activity and the growth of myelogenous leukemia cells with the IC₅₀ values of 1.13, 10.60, 0.078, and 1.84 μmol L^-1, respectively. Complexes 1 and 4 are the most active in cancer cells and in DNA cleavage.

Virtual screening and multilevel precision-based prioritisation of natural inhibitors targeting the ATPase domain of human DNA topoisomerase II alpha

Human DNA topoisomerase II alpha (hTopIIα) is a classic chemotherapeutic drug target. The existing hTopIIα poisons cause numerous side effects such as the development of cardiotoxicity, secondary malignancies, and multidrug resistance. The use of catalytic inhibitors targeting the ATP-binding cavity of the enzyme is considered a safer alternative due to the less deleterious mechanism of action. Hence, in this study, we carried out high throughput structure-based virtual screening of the NPASS natural product database against the ATPase domain of hTopIIα and identified the five best ligand hits. This was followed by comprehensive validation through molecular dynamics simulations, binding free energy calculation and ADMET analysis. On stringent multilevel prioritization, we identified promising natural product catalytic inhibitors that showed high binding affinity and stability within the ligand-binding cavity and may serve as ideal hits for anticancer drug development.Communicated by Ramaswamy H. Sarma.

Recent updates on thienopyrimidine derivatives as anticancer agents

Thienopyrimidine derivatives hold a unique place between fused pyrimidine compounds. They are important and widely represented in medicinal chemistry as they are structural analogs of purines. Thienopyrimidine derivatives have various biological activities. The current review discusses different synthetic methods for the preparation of heterocyclic thienopyrimidine derivatives. It also highlights the most recent research on the anticancer effects of thienopyrimidines through the inhibition of various enzymes and pathways, which was published within the last 9 years.

Graphical Abstract

Identification of Promising Drug Candidates against Prostate Cancer through Computationally-Driven Drug Repurposing

Prostate cancer (PC) is one of the most common types of cancer in males. Although early stages of PC are generally associated with favorable outcomes, advanced phases of the disease present a significantly poorer prognosis. Moreover, currently available therapeutic options for the treatment of PC are still limited, being mainly focused on androgen deprivation therapies and being characterized by low efficacy in patients. As a consequence, there is a pressing need to identify alternative and more effective therapeutics. In this study, we performed large-scale 2D and 3D similarity analyses between compounds reported in the DrugBank database and ChEMBL molecules with reported anti-proliferative activity on various PC cell lines. The analyses included also the identification of biological targets of ligands with potent activity on PC cells, as well as investigations on the activity annotations and clinical data associated with the more relevant compounds emerging from the ligand-based similarity results. The results led to the prioritization of a set of drugs and/or clinically tested candidates potentially useful in drug repurposing against PC.

Recent development of multi-targeted inhibitors of human topoisomerase II enzyme as potent cancer therapeutics

Multi-target therapies have been considered one of the viable options to overcome the challenges to eradicate intrinsic and acquired drug-resistant cancer cells. While to increase the efficacy of therapeutics, the use of a single drug against multiple structurally similar sites, which noncommittedly modulate several vital cellular pathways proposed as a potential alternative to a 'single drug single target'. Besides, it reduces the usage of a number of drugs and their side effects. Topoisomerase II enzyme plays a very significant role in DNA replication and thus served as an important target for numerous anti-cancer agents. However, in spite of promising clinical results, in several cases, it was found that cancer cells have developed resistance against the anti-cancer agents targeting this enzyme. Therefore, multi-target therapies have been proposed as an alternative to overcome different drug resistance mechanisms while topoisomerases II are a primary target site. In this review, we have tried to discuss the characteristics of the binding cavity available for interactions of drugs, and potent inhibitors concurrently modulate the functions of topoisomerases II as well as other structurally related target sites. Additionally, the mechanism of drug resistance by considering molecular and cellular insights by including various types of cancers.

Phytochemical Characterization of Pterocephalus frutescens with In-Silico Evaluation as Chemotherapeutic Medicine and Oral Pharmacokinetics Prediction Study

Virtual screening of the potential lead chemotherapeutic phytochemicals from medicinal plants has useful application in the field of in-silico modelling and computer-based drug design by orienting and scoring ligands in the active binding site of a target protein. The phytochemical investigation of the Pterocephalus frutescens extract in n-butanol resulted in the isolation and structure elucidation of three iridoids and four flavonoids which were identified as Geniposide (1), Geniposidic acid (2), Nepetanudoside C (3), Isovitexin (4), Luteolin-7-O-glucoside (5) Isoorientin (6) and Orientin (7), respectively. Molecular docking studies were used to compare the binding energies of the isolated phytochemicals at four biological cancer-relevant targets; namely, aromatase, carbonic anhydrase IX, fatty acid synthase, and topoisomerase II-DNA complex. The docking study concluded that the isolated compounds have promising cytotoxic activities, in particular, Luteolin-7-O-glucoside (5) and Orientin (7) which exhibited high binding affinities among the isolated compounds at the active sites of the target enzymes; Aromatase (−8.73 Kcal/mol), and Carbonic anhydrase IX (−8.92 Kcal/mol), respectively, surpassing the corresponding binding scores of the co-crystallized ligands and the reference drugs at these target enzymes. Additionally, among the isolated compounds, Luteolin-7-O-glucoside (5) showed the most outstanding binding affinities at the active sites of the target enzymes; Fatty acid synthase, and Topisomerase II-DNA complex with binding scores of −6.82, and −7.99 Kcal/mol, respectively. Finally, the SwissADME online web tool predicted that most of these compounds possessed acceptable oral bioavailability and drug likeness characteristics.

ATM inhibitor KU60019 synergistically sensitizes lung cancer cells to topoisomerase II poisons by multiple mechanisms

Type II topoisomerases (TOP2) poisons represent one class of the most successful and widely prescribed chemotherapeutics, which is frontline therapy for a myriad of systemic cancers and solid tumors, including lymphomas, leukemias, and lung cancer. Despite this, treatment with this class of drugs induces unwanted side effects (including cardiovascular morbidity and secondary malignancies). Additionally, the emergence of drug resistance also greatly compromises the clinical use of these drugs. To enhance therapeutic efficiency while lowering unwanted side effects, new insights into effective combination therapy are required. In this study we found that KU60019, a novel, and highly specific ATM kinase inhibitor interferes with the association of ATM with TOP2β and stabilizes TOP2β-DNA cleavage complex, thereby impairing the repair of TOP2 poison-induced DSBs and contributes to genome stability, leading to accelerated cell death. In H1299 as well as in A549 lung cancer cell lines, biologically, KU60019 combined with VP-16 (one of the TOP2 poisons) synergistically suppressed the growth of cells and survival and triggered a much higher apoptosis rate. In summary, we provide a proof-of-concept strategy that ATM inhibitors combined with TOP2 poison would synergistically suppresses lung cancer cell survival as well as reduce DNA damage responses, thus may lowering the possibility of cardiotoxicity and secondary malignancy linked to therapy.

OpNAC1 transcription factor regulates the biosynthesis of the anticancer drug camptothecin by targeting loganic acid O-methyltransferase in Ophiorrhiza pumila

Camptothecin (CPT) is an anticancer pentacyclic quinoline alkaloid widely used to treat cancer patients worldwide. However, the biosynthetic pathway and transcriptional regulation of camptothecin are largely unknown. Ophiorrhiza pumila, the herbaceous plant from the Rubiaceae family, has emerged as a model plant for studying camptothecin biosynthesis and regulation. In this study, a high-quality reference genome of O. pumila with estimated size of ~456.90 Mb was reported, and the accumulation level of camptothecin in roots was higher than that in stems and leaves. Based on its spatial distribution in the plant, we examined gene functions and expression by combining genomics with transcriptomic analysis. Two loganic acid O-methyltransferase (OpLAMTs) were identified in strictosidine-producing plant O. pumila, and enzyme catalysis assays showed that OpLAMT1 and not OpLAMT2 could convert loganic acid into loganin. Further knock-out of OpLAMT1 expression led to the elimination of loganin and camptothecin accumulation in O. pumila hairy roots. Four key residues were identified in OpLAMT1 protein crucial for the catalytic activity of loganic acid to loganin. By co-expression network, we identified a NAC transcription factor, OpNAC1, as a candidate gene for regulating camptothecin biosynthesis. Transgenic hairy roots and biochemical assays demonstrated that OpNAC1 suppressed OpLAMT1 expression. Here, we reported on two camptothecin metabolic engineering strategies paving the road for industrial-scale production of camptothecin in CPT-producing plants.

Upgrade of chrysomycin A as a novel topoisomerase II inhibitor to curb KRAS-mutant lung adenocarcinoma progression

A primary strategy employed in cancer therapy is the inhibition of topoisomerase II (Topo II), implicated in cell survival. However, side effects and adverse reactions restrict the utilization of Topo II inhibitors. Thus, investigations focus on the discovery of novel compounds that are capable of inhibiting the Topo II enzyme and feature safer toxicological profiles. Herein, we upgrade an old antibiotic chrysomycin A from Streptomyces sp. 891 as a compelling Topo II enzyme inhibitor. Our results show that chrysomycin A is a new chemical entity. Notably, chrysomycin A targets the DNA-unwinding enzyme Topo II with an efficient binding potency and a significant inhibition of intracellular enzyme levels. Intriguingly, chrysomycin A kills KRAS-mutant lung adenocarcinoma cells and is negligible cytotoxic to normal cells at the cellular level, thus indicating a capability of potential treatment. Furthermore, mechanism studies demonstrate that chrysomycin A inhibits the Topo II enzyme and stimulates the accumulation of reactive oxygen species, thereby inducing DNA damage-mediated cancer cell apoptosis. Importantly, chrysomycin A exhibits excellent control of cancer progression and excellent safety in tumor-bearing models. Our results provide a chemical scaffold for the synthesis of new types of Topo II inhibitors and reveal a novel target for chrysomycin A to meet its further application.

Design, synthesis, and biological evaluation of novel ciprofloxacin derivatives as potential anticancer agents targeting topoisomerase II enzyme

A series of novel ciprofloxacin (CP) derivatives substituted at the N-4 position with biologically active moieties were designed and synthesised. 14 compounds were 1.02- to 8.66-fold more potent than doxorubicin against T-24 cancer cells. Ten compounds were 1.2- to 7.1-fold more potent than doxorubicin against PC-3 cancer cells. The most potent compounds 6, 7a, 7b, 8a, 9a, and 10c showed significant Topo II inhibitory activity (83-90% at 100 μM concentration). Compounds 6, 8a, and 10c were 1.01- to 2.32-fold more potent than doxorubicin. Compounds 6 and 8a induced apoptosis in T-24 (16.8- and 20.1-fold, respectively compared to control). This evidence was supported by an increase in the level of apoptotic caspase-3 (5.23- and 7.6-fold, sequentially). Both compounds arrested the cell cycle in the S phase in T-24 cancer cells while in PC-3 cancer cells the two compounds arrested the cell cycle in the G1 phase. Molecular docking simulations of compounds 6 and 8a into the Topo II active site rationalised their remarkable Topo II inhibitory activity.

Advances in anticancer alkaloid-derived metallo-chemotherapeutic agents in the last decade: Mechanism of action and future prospects

Metal-based complexes have occupied a pioneering niche in the treatment of many chronic diseases, including various types of cancers. Despite the phenomenal success of cisplatin for the treatment of many solid malignancies, a limited number of metallo-drugs are in clinical use against cancer chemotherapy till date. While many other prominent platinum and non‑platinum- based metallo-drugs (e.g. NAMI-A, KP1019, carboplatin, oxaliplatin, titanocene dichloride, casiopeinas® etc) have entered clinical trials, many have failed at later stages of R&D due to deleterious toxic effects, intrinsic resistance and poor pharmacokinetic response and low therapeutic efficacy. Nonetheless, research in the area of medicinal inorganic chemistry has been increasing exponentially over the years, employing novel target based drug design strategies aimed at improving pharmacological outcomes and at the same time mitigating the side-effects of these drug entities. Over the last few decades, natural products became one of the key structural motifs in the anticancer drug development. Many eminent researchers in the area of medicinal chemistry are devoted to develop new 3d-transition metal-based anticancer drugs/repurpose the existing bioactive compounds derived from myriad pharmacophores such as coumarins, flavonoids, chromones, alkaloids etc. Metal complexes of natural alkaloids and their analogs such as luotonin A, jatrorrhizine, berberine, oxoaporphine, 8-oxychinoline etc. have gained prominence in the anticancer drug development process as the naturally occurring alkaloids can be anti-proliferative, induce apoptosis and exhibit inhibition of angiogenesis with better healing effect. While some of them are inhibitors of ERK signal-regulated kinases, others show activity based on cyclooxygenases-2 (COX-2) and telomerase inhibition. However, the targets of these alkaloid complexes are still unclear, though it is well-established that they demonstrate anticancer potency by interfering with multiple pathways of tumorigenesis and tumor progression both in vitro and in vivo. Over the last decade, many significant advances have been made towards the development of natural alkaloid-based metallo-drug therapeutics for intervention in cancer chemotherapy that have been summarized below and reviewed in this article.

Phytochemicals as Chemo-Preventive Agents and Signaling Molecule Modulators: Current Role in Cancer Therapeutics and Inflammation

Cancer is one of the deadliest non communicable diseases. Numerous anticancer medications have been developed to target the molecular pathways driving cancer. However, there has been no discernible increase in the overall survival rate in cancer patients. Therefore, innovative chemo-preventive techniques and agents are required to supplement standard cancer treatments and boost their efficacy. Fruits and vegetables should be tapped into as a source of compounds that can serve as cancer therapy. Phytochemicals play an important role as sources of new medication in cancer treatment. Some synthetic and natural chemicals are effective for cancer chemoprevention, i.e., the use of exogenous medicine to inhibit or impede tumor development. They help regulate molecular pathways linked to the development and spread of cancer. They can enhance antioxidant status, inactivating carcinogens, suppressing proliferation, inducing cell cycle arrest and death, and regulating the immune system. While focusing on four main categories of plant-based anticancer agents, i.e., epipodophyllotoxin, camptothecin derivatives, taxane diterpenoids, and vinca alkaloids and their mode of action, we review the anticancer effects of phytochemicals, like quercetin, curcumin, piperine, epigallocatechin gallate (EGCG), and gingerol. We examine the different signaling pathways associated with cancer and how inflammation as a key mechanism is linked to cancer growth.

Dual Topoisomerase I/II Inhibition-Induced Apoptosis and Necro-Apoptosis in Cancer Cells by a Novel Ciprofloxacin Derivative via RIPK1/RIPK3/MLKL Activation

Fluoroquinolones (FQs) are synthetic broad-spectrum antimicrobial agents that have been recently repurposed to anticancer candidates. Designing new derivatives of FQs with different moieties to target DNA topoisomerases could improve their anticancer efficacy. The present study aimed to synthesize a novel ciprofloxacin derivative, examine its anticancer activity against HepG2 and A549 cancer cells, and investigate the possible molecular mechanism underlying this activity by examining its ability to inhibit the topo I/II activity and to induce the apoptotic and necro-apoptotic pathways. Molecular docking, cell viability, cell migration, colony formation, cell cycle, Annexin V, lactate dehydrogenase (LDH) release, ELISA, and western blotting assays were utilized. Molecular docking results showed that this novel ciprofloxacin derivative exerted dual topo I and topo II binding and inhibition. It significantly inhibited the proliferation of A549 and HepG2 cancer cells and decreased their cell migration and colony formation abilities. In addition, it significantly increased the % of apoptotic cells, caused cell cycle arrest at G2/M phase, and elevated the LDH release levels in both cancer cells. Furthermore, it increased the expression of cleaved caspase 3, RIPK1, RIPK3, and MLKL proteins. This novel ciprofloxacin derivative exerted substantial dual inhibition of topo I/II enzyme activities, showed antiproliferative activity, suppressed the cell migration and colony formation abilities for A549 and HepG2 cancer cells and activated the apoptotic pathway. In addition, it initiated another backup deadly pathway, necro-apoptosis, through the activation of the RIPK1/RIPK3/MLKL pathway.

Dual Targeting Topoisomerase/G-Quadruplex Agents in Cancer Therapy-An Overview

Topoisomerase (Topo) inhibitors have long been known as clinically effective drugs, while G-quadruplex (G4)-targeting compounds are emerging as a promising new strategy to target tumor cells and could support personalized treatment approaches in the near future. G-quadruplex (G4) is a secondary four-stranded DNA helical structure constituted of guanine-rich nucleic acids, and its stabilization impairs telomere replication, triggering the activation of several protein factors at telomere levels, including Topos. Thus, the pharmacological intervention through the simultaneous G4 stabilization and Topos inhibition offers a new opportunity to achieve greater antiproliferative activity and circumvent cellular insensitivity and resistance. In this line, dual ligands targeting both Topos and G4 emerge as innovative, efficient agents in cancer therapy. Although the research in this field is still limited, to date, some chemotypes have been identified, showing this dual activity and an interesting pharmacological profile. This paper reviews the available literature on dual Topo inhibitors/G4 stabilizing agents, with particular attention to the structure-activity relationship studies correlating the dual activity with the cytotoxic activity.

Targeting DNA Topoisomerase II in Antifungal Chemotherapy

Topoisomerase inhibitors have been in use clinically for the treatment of several diseases for decades. Although those enzymes are significant molecular targets in antibacterial and anticancer chemotherapy very little is known about the possibilities to target fungal topoisomerase II (topo II). Raising concern for the fungal infections, lack of effective drugs and a phenomenon of multidrug resistance underlie a strong need to expand the range of therapeutic options. In this review paper, we discussed the usefulness of fungal topo II as a molecular target for new drug discovery. On the basis of previously published data, we described structural and biochemical differences between fungal and human enzymes as well as a molecular basis of differential sensitivity to known anticancer drugs targeting the latter. This review focuses especially on highlighting the differences that may underlie the selectivity of action of new inhibitors. Distinct sites within fungal topo II in comparison with human counterparts are observed and should be further studied to understand the significance of those sites and their possible usage in design of new drugs.

Nb/Starch-Doped ZnO Nanostructures for Polluted Water Treatment and Antimicrobial Applications: Molecular Docking Analysis

Nb/starch-doped ZnO quantum dots (QDs) were prepared by a coprecipitation route. A fixed quantity of starch (st) and different concentrations (2 and 4%) of niobium (Nb) were doped in a ZnO lattice. To gain a better understanding of synthesized nanostructures, a systematic study was carried out utilizing several characterization methods. The goal of this research was to undertake methylene blue (MB) dye degradation with a synthetic material and also study its antibacterial properties. The phase structure, morphology, functional groups, optical properties, and elemental compositions of synthesized samples were investigated. Our study showed that ZnO QDs enhanced photocatalytic activity (PCA), resulting in effective MB degradation, in addition to showing good antimicrobial activity against Gram-negative relative to Gram-positive bacteria. Molecular docking study findings were in good agreement with the observed in vitro bactericidal potential and suggested ZnO, st-ZnO, and Nb/st-ZnO as possible inhibitors against dihydrofolate reductase (DHFR_E. coli) and DNA gyrase_E. coli.

JNC-1043, a Novel Podophyllotoxin Derivative, Exerts Anticancer Drug and Radiosensitizer Effects in Colorectal Cancer Cells

The objective of this study was to determine whether (5S)-5-(4-benzyloxy-3,5-dimethoxy-phenyl)-5,9-dihydro-8H-furo [3’,4’:6,7] naphtho [2,3-d] [1,3]dioxol-6-one (JNC-1043), which is a novel chemical derivative of β-apopicropodophyllin, acts as a novel potential anticancer reagent and radiosensitizer in colorectal cancer (CRC) cells. Firstly, we used MTT assays to assess whether JNC-1043 could inhibit the cell proliferation of HCT116 and DLD-1 cells. The IC50 values of these cell lines were calculated as 114.5 and 157 nM, respectively, at 72 h of treatment. Using doses approximating the IC50 values, we tested whether JNC-1043 had a radiosensitizing effect in the CRC cell lines. Clonogenic assays revealed that the dose-enhancement ratios (DER) of HCT116 and DLD-1 cells were 1.53 and 1.25, respectively. Cell-counting assays showed that the combination of JNC-1043 and γ-ionizing radiation (IR) enhanced cell death. Treatment with JNC-1043 or IR alone induced cell death by 50~60%, whereas the combination of JNC-1043 and IR increased this cell death by more than 20~30%. Annexin V-propidium iodide assays showed that the combination of JNC-1043 and IR increased apoptosis by more 30~40% compared to that induced by JNC-1043 or IR alone. DCFDA- and MitoSOX-based assays revealed that mitochondrial ROS production was enhanced by the combination of JNC-1043 and IR. Finally, we found that suppression of ROS by N-acetylcysteine (NAC) blocked the apoptotic cell death induced by the combination of JNC-1043 and IR. The xenograft model also indicated that the combination of JNC-1043 and IR increased apoptotic cell death in tumor mass. These results collectively suggest that JNC-1043 acts as a radiosensitizer and exerts anticancer effects against CRC cells by promoting apoptosis mediated by mitochondrial ROS.

Insight on the Interaction between the Camptothecin Derivative and DNA Oligomer Mimicking the Target of Topo I Inhibitors

The understanding of the mechanism of Topo I inhibition by organic ligands is a crucial source of information that has led to the design of more effective and safe pharmaceuticals in oncological chemotherapy. The vast number of inhibitors that have been studied in this respect over the last decades have enabled the creation of a concept of an ‘interfacial inhibitor’, thereby describing the machinery of Topo I inhibition. The central module of action of this machinery is the interface of a Topo I/DNA/inhibitor ternary complex. Most of the ‘interfacial inhibitors’ are primarily kinetic inhibitors that form molecular complexes with an “on–off” rate timing; therefore, all of the contacts between the inhibitor and both the enzyme and the DNA are essential to keep the complex stable and reduce the “off rate”. To test this hypothesis, we designed the compound using a C-9-(N-(2′-hydroxyethyl)amino)methyl substituent in an SN38 core, with a view that a flexible substituent may bind inside the nick of a model of the DNA and stabilize the complex, leading to a reduction in the “off rate” of a ligand in a potential ternary complex in vivo. Using docking analysis and molecular dynamics, free energy calculations on the level of the MM-PBSA and MM-GBSA model, here we presented the in silico-calculated structure of a ternary complex involving the studied compound 1. This confirmed our suggestion that compound 1 is situated in a groove of the nicked DNA model in a few conformations. The number of hydrogen bonds between the components of a ternary complex was established, which strengthens the complex and supports our view. The docking analysis and free energy calculations for the receptor structures which were obtained in the MD simulations of the ternary complex 1/DNA/Topo I show that the binding constant is stronger than it was for similar complexes with TPT, CPT, and SN38, which are commonly considered as strong Topo I inhibitors. The binary complex structure 1/DNA was calculated and compared with the experimental results of a complex that was in a solution. The analysis of the cross-peaks in NOESY spectra allowed us to assign the dipolar interactions between the given protons in the calculated structures. A DOSY experiment in the solution confirmed the strong binding of a ligand in a binary complex, having a K_a of 746 mM⁻¹, which was compared with a K_a of 3.78 mM⁻¹ for TPT. The MALDI-ToF MS showed the presence of the biohybrid, thus evidencing the occurrence of DNA alkylation by compound 1. Because of it having a strong molecular complex, alkylation is the most efficient way to reduce the “on–off” timing as it acts as a tool that causes the cog to brake in a working gear, and this is this activity we want to highlight in our contribution. Finally, the Topo I inhibition test showed a lower IC₅₀ of the studied compound than it did for CPT and SN38.

Novel and Structurally Diversified Bacterial DNA Gyrase Inhibitors Discovered through a Fluorescence-Based High-Throughput Screening Assay

Bacterial DNA gyrase, a type IIA DNA topoisomerase that plays an essential role in bacterial DNA replication and transcription, is a clinically validated target for discovering and developing new antibiotics. In this article, based on a supercoiling-dependent fluorescence quenching (SDFQ) method, we developed a high-throughput screening (HTS) assay to identify inhibitors targeting bacterial DNA gyrase and screened the National Institutes of Health's Molecular Libraries Small Molecule Repository library containing 370,620 compounds in which 2891 potential gyrase inhibitors have been identified. According to these screening results, we acquired 235 compounds to analyze their inhibition activities against bacterial DNA gyrase using gel- and SDFQ-based DNA gyrase inhibition assays and discovered 155 new bacterial DNA gyrase inhibitors with a wide structural diversity. Several of them have potent antibacterial activities. These newly discovered gyrase inhibitors include several DNA gyrase poisons that stabilize the gyrase-DNA cleavage complexes and provide new chemical scaffolds for the design and synthesis of bacterial DNA gyrase inhibitors that may be used to combat multidrug-resistant bacterial pathogens. Additionally, this HTS assay can be applied to screen inhibitors against other DNA topoisomerases.

Suppressing crucial oncogenes of leukemia initiator cells by major royal jelly protein 2 for mediating apoptosis in myeloid and lymphoid leukemia cells

Relapse of leukemia and drug resistance are still the major obstacles to therapy due to leukemia-initiating stem/progenitor cells (LICs); thus, targeting them using safe compounds is crucial. Here, we evaluated the anti-leukemic effect of royal jelly (RJ) components, which had a higher safe concentration (EC₁₀₀ values) than the chemotherapeutic drug doxorubicin (DOX). The RJ-protein fraction 50 (PF₅₀, precipitated at 40-50% ammonium sulfate saturation) and its constituents, major RJ protein (MRJP) 2 and its isoform X1, exhibited the highest growth inhibitory effect against myeloid NFS-60 and lymphoid Jurkat cell lines. MRJP2 has a nanosize, which may be the reason for its higher anti-leukemic activity than its isoform. These RJ proteins, particularly MRJP2, suppressed LIC-associated oncogenes (GATA2 and Evi-1) and eliminated CD34⁺ LICs, in contrast to the low anti-LIC efficacy of DOX. MRJP2 demonstrated higher apoptotic activity than its isoform by upregulating p53 and p21-mediated cell cycle arrest. This study also reported the potent inhibitory effect of RJ-proteins on matrix metallopeptidase 10 (metastatic marker) and histone deacetylase 8 (mediates LIC survival) activities. Thus, MRJP2 can be considered a promising novel therapeutic agent for both myeloid and lymphoid leukemia.