Multiple Topoisomerase I (TopoI), Topoisomerase II (TopoII) and Tyrosyl-DNA Phosphodiesterase (TDP) inhibitors in the development of anticancer drugs

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

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.

NHC-Ag(I) and NHC-Au(I) Complexes with N-Boc-Protected α-Amino Acidate Counterions Powerfully Affect the Growth of MDA-MB-231 Cells

N-Heterocyclic carbene (NHC) metal complexes are attracting scientists' interest as an alluring class of metallodrugs. Indeed, the versatile functionalization of NHC ligands makes them optimal scaffolds to be developed in medicinal chemistry. Besides, amino acids are great biological ligands for metals, such as silver and gold, even though their use is still under-investigated. Aiming to shed light on the anticancer properties of this kind of complex, we investigated a series of silver and gold complexes, stabilized by NHC ligands and bearing carboxylate salts of tert-butyloxycarbonyl (Boc)-N-protected glycine and l-phenylalanine as anionic ligands. The most active complexes, AuM1Gly and AuM1Phe, powerfully affect the growth of MDA-MB-231 breast cancer cells, with IC50 values in the low nanomolar range. Further studies demonstrated the blockade of the human topoisomerase I activity and actin polymerization reaction at 0.001 μM. These unique features make these complexes very interesting and worthy to be used for future in vivo studies.

Evaluation of the Anticancer and Biological Activities of Istaroxime via Ex Vivo Analyses, Molecular Docking and Conceptual Density Functional Theory Computations

Cancer is a disease that occurs as a result of abnormal or uncontrolled growth of cells due to DNA damage, among many other causes. Certain cancer treatments aim to increase the excess of DNA breaks to such an extent that they cannot escape from the general mechanism of cell checkpoints, leading to the apoptosis of mutant cells. In this study, one of the Sarco-endoplasmic reticulum Ca2+ATPase (SERCA2a) inhibitors, Istaroxime, was investigated. There has been very limited number of articles so far reporting Istaroxime's anticancer activity; thus, we aimed to evaluate the anticancer effects of Istaroxime by cell proliferation assay and revealed the cytotoxic activity of the compound. We further determined the interaction of Istaroxime with topoisomerase enzymes through enzyme activity tests and detailed molecular modeling analysis. Istaroxime exhibited an antiproliferative effect on A549, MCF7, and PC3 cell lines and inhibited Topoisomerase I, suggesting that Istaroxime can act as a Topoisomerase I inhibitor under in vitro conditions. Molecular docking analysis supported the experimental observations. A chemical reactivity analysis of the Istaroxime molecule was made in the light of Density Functional Theory computations. For this aim, important chemical reactivity descriptors such as hardness, electronegativity, and electrophilicity were computed and discussed as detailed.

Silver complexes with substituted terpyridines as promising anticancer metallodrugs and their crystal structure, photoluminescence, and DNA interactions

Six silver hexafluoroantimonate complexes (1-6) with 4'-(4'-substituted-phenyl)-2,2':6',2''-terpyridine compounds bearing hydrogen (L1), methyl (L2), methylsulfonyl (L3), chloro (L4), bromo (L5) and iodo (L6) were prepared and characterized by 1H NMR, 13C NMR, IR, elemental analysis and single crystal X-ray diffraction. All the compounds exhibit interesting photoluminescence properties in the solid state and solution. In vitro data demonstrate that all of them show higher antiproliferative activities than cisplatin against three human carcinoma cell lines, A549, Eca-109 and MCF-7. Compound 3 exhibits the lowest IC50 value (2.298 μM) against A549 cell lines, which is 2.963 μM for 4 against Eca-109 and 1.830 μM for 1 against MCF-7. For silver halogen-substituted terpyridine compounds, their anticancer activities decrease following the sequence of -Cl, -Br, and -I substituents. The comparison results show that their anticancer activity is significantly higher than that of their free ligands. The DNA interaction was studied by fluorescence titration, circular dichroism spectroscopy and molecular modeling methods. Spectrophotometric results reveal that the compounds have strong affinity binding with DNA as intercalators and molecular docking studies indicate that the binding is contributed by the π-π stacking and hydrogen bonds. The DNA binding ability of the complexes has been correlated with their anticancer activities, which could potentially provide a new rationale for the future design of terpyridine-based metal complexes with antitumor potential.

Synthesis and Biological Activities of 11- and 12-Substituted Benzophenanthridinone Derivatives as DNA Topoisomerase IB and Tyrosyl-DNA Phosphodiesterase 1 Inhibitors

Herein, a series of 11- or 12-substituted benzophenanthridinone derivatives was designed and synthesized for the discovery of dual topoisomerase IB (TOP1) and tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors. Enzyme-based assays indicated that two compounds 12 and 38 showed high TOP1 inhibitory potency (+++), and four compounds 35, 37, 39 and 43 showed good TDP1 inhibition with IC50 values ranging from 10 to 18 μM. 38 could induce cellular TOP1cc formation, resulting in the highest cytotoxicity against HCT-116 cells (0.25 μM). The most potent TDP1 inhibitor 43 (10 μM) could induce cellular TDP1cc formation and enhance topotecan-induced DNA damage and showed strong synergistic cytotoxicity with topotecan in both MCF-7 and MCF-7/TDP1 cells.

Synthesis, spectroscopic characterization, molecular docking and in vitro cytotoxicity investigations on 8-Amino-6-Methoxy Quinolinium Picrate: a novel breast cancer drug

Density Functional Theory (DFT) studies of the 8-Amino-6-Methoxy Quinolinium Picrate (8A6MQP) molecule have been carried out with extensive and accurate investigations of detailed vibrational and spectroscopic investigations as well as validated experimentally. The 8A6MQP sample was synthesized and characterized using FT-IR, FT-Raman, FT-NMR and UV-Vis spectroscopic techniques. Subsequently, the optimized molecular structure and harmonic resonance frequencies of the molecule were computed based on DFT/B3LYP method with a 6-311G++(d,p) basis set using the Gaussian 09 program. The experimental and calculated vibrational wavenumbers were assigned. The absorption spectrum of the molecule was computed in the liquid phase (ethanol), which exhibits n to л* electronic transition and compared with the observed UV-Vis spectrum. Frontier molecular orbital analysis shows the molecular reactivity and kinetic stability of the molecule. The Mulliken atomic charge distribution and molecular electrostatic potential surface analysis of the molecule validate the reactive site of the molecule. The natural bond orbital analysis proves the bioactivity of the molecule. Molecular docking analysis indicates that the 8A6MQP molecule inhibits the action of DNA topoisomerase 2-alpha protein, which is associated with breast cancer. In addition, the in vitro cytotoxicity analysis of the 8A6MQP molecule against human cervical cancer cell lines (ME180) and human breast cancer cell lines (MDA MB 231) were determined by MTT assay, which evidences that the title molecule exhibits higher inhibition against the breast cancer cell lines compared to that of cervical cancer cell lines. Hence, the present study paves the way for the development of novel drugs in the treatment of breast cancer.Communicated by Ramaswamy H. Sarma.

G-quadruplex-containing oligodeoxynucleotides as DNA topoisomerase I inhibitors

DNA topoisomerase I was found to be highly abundant in fast-proliferating tumor cells and is a potential target for anticancer therapy. A series of G-quadruplex-containing oligodeoxynucleotides (ODNs) were designed and used as inhibitors of DNA topoisomerase I. It was demonstrated that ODNs with G-quadruplexes can efficiently inhibit the supercoiled DNA relaxation reaction catalyzed by DNA topoisomerase I. Compared with the other conformations, the parallel propeller-type G-quadruplex was the most efficient DNA topoisomerase I inhibitor. Further studies revealed that integrating G-quadruplexes with duplexes to form quadruplex-duplex hybrids could significantly improve the inhibition efficiency. In addition, a circular ODN that consists of a G-quadruplex motif and DNA topoisomerase I binding site was synthesized and used as a DNA topoisomerase I inhibitor. The results showed that the particularly designed circular ODN displayed high inhibitory efficiency on the activity of DNA topoisomerase I with an IC₅₀ value of 54.8 nM. Moreover, the circular ODN exhibited excellent thermal stability and nuclease resistance. Considering the low cytotoxicity of DNA-based biopharmaceuticals, the design strategy and results reported in this study may shed new light on nucleic acid-based DNA topoisomerase I inhibitor construction for potential anticancer drugs.

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.

Transcriptomics and Proteomics Characterizing the Anticancer Mechanisms of Natural Rebeccamycin Analog Loonamycin in Breast Cancer Cells

The present study is to explore the anticancer effect of loonamycin (LM) in vitro and in vivo, and investigate the underlying mechanism with combined multi-omics. LM exhibited anticancer activity in human triple negative breast cancer cells by promoting cell apoptosis. LM administration inhibited the growth of MDA-MB-468 tumors in a murine xenograft model of breast cancer. Mechanistic studies suggested that LM could inhibit the topoisomerase I in a dose-dependent manner in vitro experiments. Combined with the transcriptomics and proteomic analysis, LM has a significant effect on O-glycan, p53-related signal pathway and EGFR/PI3K/AKT/mTOR signal pathway in enrichment of the KEGG pathway. The GSEA data also suggests that the TNBC cells treated with LM may be regulated by p53, O-glycan and EGFR/PI3K/AKT/mTOR signaling pathway. Taken together, our findings predicted that LM may target p53 and EGFR/PI3K/AKT/mTOR signaling pathway, inhibiting topoisomerase to exhibit its anticancer effect.

Discovery of Quinacrine as a Potent Topo II and Hsp90 Dual-Target Inhibitor, Repurposing for Cancer Therapy

Topo II and Hsp90 are promising targets. In this study, we first verified the structural similarities between Topo IIα ATPase and Hsp90α N−ATPase. Subsequently, 720 compounds from the Food and Drug Administration (FDA) drug library and kinase library were screened using the malachite green phosphate combination with the Topo II-mediated DNA relaxation and MTT assays. Subsequently, the antimalarial drug quinacrine was found to be a potential dual−target inhibitor of Topo II and Hsp90. Mechanistic studies showed that quinacrine could specifically bind to the Topo IIα ATPase domain and inhibit the activity of Topo IIα ATPase without impacting DNA cleavage. Furthermore, our study revealed that quinacrine could bind Hsp90 N−ATPase and inhibit Hsp90 activity. Significantly, quinacrine has broad antiproliferation activity and remains sensitive to the multidrug−resistant cell line MCF−7/ADR and the atypical drug−resistant tumor cell line HL−60/MX2. Our study identified quinacrine as a potential dual−target inhibitor of Topo II and Hsp90, depending on the ATP−binding domain, positioning it as a hit compound for further structural modification.

New 1,2,3-triazole linked ciprofloxacin-chalcones induce DNA damage by inhibiting human topoisomerase I& II and tubulin polymerization

A series of novel 1,2,3-triazole-linked ciprofloxacin-chalcones 4a-j were synthesised as potential anticancer agents. Hybrids 4a-j exhibited remarkable anti-proliferative activity against colon cancer cells. Compounds 4a-j displayed IC₅₀s ranged from 2.53-8.67 µM, 8.67-62.47 µM, and 4.19-24.37 µM for HCT116, HT29, and Caco-2 cells; respectively, whereas the doxorubicin, showed IC₅₀ values of 1.22, 0.88, and 4.15 µM. Compounds 4a, 4b, 4e, 4i, and 4j were the most potent against HCT116 with IC₅₀ values of 3.57, 4.81, 4.32, 4.87, and 2.53 µM, respectively, compared to doxorubicin (IC₅₀ = 1.22 µM). Also, hybrids 4a, 4b, 4e, 4i, and 4j exhibited remarkable inhibitory activities against topoisomerase I, II, and tubulin polymerisation. They increased the protein expression level of γH2AX, indicating DNA damage, and arrested HCT116 in G2/M phase, possibly through the ATR/CHK1/Cdc25C pathway. Thus, the novel ciprofloxacin hybrids could be exploited as potential leads for further investigation as novel anticancer medicines to fight colorectal carcinoma.

The design and discovery of topoisomerase I inhibitors as anticancer therapies

INTRODUCTION

Cancer has been identified as one of the leading causes of death worldwide. The biological target of some anticancer agents is topoisomerase I, an enzyme involved in the relaxation of supercoiled DNA. The synthesis of new compounds with antiproliferative effect and behaving as topoisomerase I inhibitors has become an active field of research. Depending on their mechanism of inhibition, they can be classified as catalytic inhibitors or poisons.

AREAS COVERED

This review article summarizes the state of the art for the development of selective topoisomerase I inhibitors. Collected compounds showed inhibition of the enzyme, highlighting those approved for clinical use, the combination therapies developed, as well as related drawbacks and future focus.

EXPERT OPINION

Research related to topoisomerase I inhibitors in cancer therapy started with camptothecin (CPT). This compound was first selected as a good anticancer agent and then topoisomerase I was identified as its therapeutic target. Derivatives of CPT irinotecan, topotecan, and belotecan are the only clinically approved inhibitors. Currently, their limitations are being addressed by different stretegies. Future studies should focus not only on developing other active molecules but also on improving the bioavailability and pharmacokinetics of potent synthetic derivatives.

Dual-target inhibitors based on PARP1: new trend in the development of anticancer research

PARP1 is a hot target, and its inhibitors have been approved for cancer therapy. However, some undesirable properties restrict the application of PARP1 inhibitors, including drug resistance, side effects and low efficiency. For multifactorial diseases, dual-target drugs have exhibited excellent synergistic effects, such as reduced drug resistance, low side effects and high therapeutic efficacy, by simultaneously regulating the main pathogenic and compensatory signal pathways of diseases. In recent years, several dual-target inhibitors based on PARP1 have been reported and have demonstrated unique advantages. In this review we summarize the research progress in dual-target inhibitors based on PARP1 and discuss the related drug design strategies and structure-activity relationships. This work is expected to provide references for the development of PARP1 inhibitors.

Drug Resistance and Endoplasmic Reticulum Stress in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and deadly cancers worldwide. It is usually diagnosed in an advanced stage and is characterized by a high intrinsic drug resistance, leading to limited chemotherapeutic efficacy and relapse after treatment. There is therefore a vast need for understanding underlying mechanisms that contribute to drug resistance and for developing therapeutic strategies that would overcome this. The rapid proliferation of tumor cells, in combination with a highly inflammatory microenvironment, causes a chronic increase of protein synthesis in different hepatic cell populations. This leads to an intensified demand of protein folding, which inevitably causes an accumulation of misfolded or unfolded proteins in the lumen of the endoplasmic reticulum (ER). This process is called ER stress and triggers the unfolded protein response (UPR) in order to restore protein synthesis or—in the case of severe or prolonged ER stress—to induce cell death. Interestingly, the three different arms of the ER stress signaling pathways have been shown to drive chemoresistance in several tumors and could therefore form a promising therapeutic target. This review provides an overview of how ER stress and activation of the UPR contributes to drug resistance in HCC.

Design, synthesis and bioactivity evaluation of novel N-phenyl-substituted evodiamine derivatives as potent anti-tumor agents

Natural products are important sources for the development of therapeutic medicine, among which evodia fruit has a wide range of medicinal properties in traditional Chinese medicine. Evodiamine, the main active component of evodia fruit, has various anti-cancer effects and has been proved to be a Topo inhibitor. From our previous attempts of modifying evodiamine, we found that the N14 phenyl substituted derivatives had showed great anti-tumor activity, which prompted us to further explore the novel structures and activities of these compounds. Compound 6f, as a N14 3-fluorinated phenyl substituted evodiamine derivative, showed a certain inhibitory activity against Topo I at 200 μM. By studying its anti-tumor effects in vitro, compound 6f could inhibit proliferation and induce apoptosis, as well as arrest the cell cycle of HGC-27 and HT-29 cell lines at G2/M phase in a concentration-dependent manner. Moreover, compound 6f could inhibit the migration and invasion of HGC-27 cell lines. Meanwhile, compound 6f could induce apoptosis of HGC-27 cells by inhibiting PI3K/AKT pathway. Overall, this work demonstrated that the N14 phenyl-substituted evodiamine derivatives had a good inhibitory effect on tumor cells in vitro, providing a promising strategy for developing potential anticancer agents for the treatment of gastrointestinal tumors.

Identification of new halogen-containing 2,4-diphenyl indenopyridin-5-one derivative as a boosting agent for the anticancer responses of clinically available topoisomerase inhibitors

Based on previous reports on the significance of halogen moieties and the indenopyridin-5-one skeleton, we designed and synthesized a novel series of halogen (F-, Cl-, Br-, CF₃- and OCF₃-)-containing 2,4-diphenyl indenopyridin-5-ones and their corresponding -5-ols. Unlike indenopyridin-5-ols, most of the prepared indenopyridin-5-ones with Cl-, Br-, and CF₃- groups at the 2-phenyl ring conferred a strong dual topoisomerase I/IIα inhibitory effect. Among the series, para-bromophenyl substituted compound 9 exhibited the most potent topoisomerase inhibition and antiproliferative effects, which showed dependency upon the topoisomerase gene expression level of diverse cancer cells. In particular, as a DNA minor groove-binding non-intercalative topoisomerase I/IIα catalytic inhibitor, compound 9 synergistically promoted the anticancer efficacy of clinically applied topoisomerase I/IIα poisons both in vitro and in vivo, having the great advantage of alleviating poison-related toxicities.

The Novel Dual Topoisomerase Inhibitor P8-D6 Shows Anti-myeloma Activity In Vitro and In Vivo

P8-D6 is a novel dual inhibitor of human topoisomerase I (TOP1) and II (TOP2) with broad pro-apoptotic antitumor activity. NCI-60 screening revealed markedly improved cytotoxicity of P8-D6 against solid and leukemia cell lines compared with other single and dual topoisomerase inhibitors, for example, irinotecan, doxorubicin, or pyrazoloacridine. In this study, we investigated the capacity of P8-D6 to inhibit myeloma cell growth in vitro and in vivo Growth inhibition assays demonstrated significant anti-myeloma effects against different myeloma cell lines with IC₅₀ values in the low nanomolar range. Freshly isolated plasma cells of patients with multiple myeloma were killed by P8-D6 with similar doses. P8-D6 activated caspase 3/7 and induced significant apoptosis of myeloma cells. Supportive effects of bone marrow stromal cells on IL6-dependent INA-6 myeloma cells were abrogated by P8-D6 and apoptosis occurred in a time- and dose-dependent manner. Of note, healthy donor peripheral blood mononuclear cells and human umbilical vein endothelial cells were not affected at concentrations toxic for malignant plasma cells. Treatment of myeloma xenografts in immunodeficient SCID/beige mice by intravenous and, notably, also oral application of P8-D6 markedly inhibited tumor growths, and significantly prolonged survival of tumor-bearing mice.

Up-regulation of GSTT1 in serous ovarian cancer associated with resistance to TAXOL / carboplatin

Serous ovarian cancer (SOC) is the most common women cancer and the leading cause of cancer-related mortality among the gynaecological malignancies. Although effective chemotherapeutics combined with surgery are developed for the treatment, the five-year survival rate is unsatisfactory due to chemoresistance. To overcome this shortcoming of chemotherapy, we established taxol and carboplatin resistant SOC cell lines for the understandings of the molecular and cellular mechanisms of chemoresistance. Here, we found that these chemoresistant cell lines showed less viability and proliferation, due to more cells arrested at G0/G1 phase. Glutathione-S-transferases-theta1 (GSTT1) was significantly upregulated in these chemoresistant cells, along with other chemoresistant genes. Meanwhile, GSTT1 expression was also significantly upregulated in the SOC patient tissues after taxol treatment, indicating this upregulation was physiologically relevant to chemotherapy. Further, suppression of GSTT1 expression by shRNA in SOC cell lines led to more sensitivity to drug treatment, through increasing divided cells and promoting cell death. Moreover, the expression of DNA topoisomerase 1 (Topo I) was in synergy with that of GSTT1 in the chemoresistant cells, and GSTT1 can bind to Topo I in vitro, which suggested GSTT1 could function through DNA repair mechanism during chemoresistance. In summary, our data imply that GSTT1 may be a potential biomarker or indicator of drug resistance in serous ovarian cancer.

Synthesis of Methoxy-, Methylenedioxy-, Hydroxy-, and Halo-Substituted Benzophenanthridinone Derivatives as DNA Topoisomerase IB (TOP1) and Tyrosyl-DNA Phosphodiesterase 1 (TDP1) Inhibitors and Their Biological Activity for Drug-Resistant Cancer

As a recently discovered DNA repair enzyme, tyrosyl-DNA phosphodiesterase 1 (TDP1) removes topoisomerase IB (TOP1)-mediated DNA protein cross-links. Inhibiting TDP1 can potentiate the cytotoxicity of TOP1 inhibitors and overcome cancer cell resistance to TOP1 inhibitors. On the basis of our previous study, herein we report the synthesis of benzophenanthridinone derivatives as TOP1 and TDP1 inhibitors. Seven compounds (C2, C4, C5, C7, C8, C12, and C14) showed a robust TOP1 inhibitory activity (+++ or ++++), and four compounds (A13, C12, C13, and C26) showed a TDP1 inhibition (half-maximal inhibitory concentration values of 15 or 19 μM). We also show that the dual TOP1 and TDP1 inhibitor C12 induces both cellular TOP1cc, TDP1cc formation and DNA damage, resulting in cancer cell apoptosis at a sub-micromolar concentration. In addition, C12 showed an enhanced activity in drug-resistant MCF-7/TDP1 cancer cells and was synergistic with topotecan in both MCF-7 and MCF-7/TDP1 cells.

Design, Synthesis, and Molecular Docking Study of New Tyrosyl-DNA Phosphodiesterase 1 (TDP1) Inhibitors Combining Resin Acids and Adamantane Moieties

In this paper, a series of novel abietyl and dehydroabietyl ureas, thioureas, amides, and thioamides bearing adamantane moieties were designed, synthesized, and evaluated for their inhibitory activities against tyrosil-DNA-phosphodiesterase 1 (TDP1). The synthesized compounds were able to inhibit TDP1 at micromolar concentrations (0.19–2.3 µM) and demonstrated low cytotoxicity in the T98G glioma cell line. The effect of the terpene fragment, the linker structure, and the adamantane residue on the biological properties of the new compounds was investigated. Based on molecular docking results, we suppose that adamantane derivatives of resin acids bind to the TDP1 covalent intermediate, forming a hydrogen bond with Ser463 and hydrophobic contacts with the Phe259 and Trp590 residues and the oligonucleotide fragment of the substrate.

Synthesis and Biological Activity of Ferrocenyl and Ruthenocenyl Analogues of Etoposide: Discovery of a Novel Dual Inhibitor of Topoisomerase II Activity and Tubulin Polymerization

Two series of the ferrocenyl and ruthenocenyl analogues of etoposide bearing 1,2,3-triazolyl or aminoalkyl linker were synthesized and evaluated for their cytotoxic properties, influence on the cell cycle, ability to induce tubulin polymerization, and inhibition of topoisomerase II activity. We found that the replacement of the etoposide carbohydrate moiety with a metallocenyl group led to organometallic conjugates exhibiting differentiated antiproliferative activity. Biological studies demonstrated that two ferrocenylalkylamino conjugates were notably more active than etoposide, with submicromolar or low-micromolar IC₅₀ values towards SW620, etoposide-resistant SW620E, and methotrexate-resistant SW620M cancer cell lines. Moreover, the simplest ferrocenylmethylamino conjugate exerted dual inhibitory action against tubulin polymerization and topoisomerase II activity while other studied compounds affected only topoisomerase II activity.

Identification of Anti-Inflammatory and Anti-Proliferative Neolignanamides from Warburgia ugandensis Employing Multi-Target Affinity Ultrafiltration and LC-MS

Previous reports have illustrated that the incidence and mortality of cancer are increasing year by year worldwide. In addition, the occurrence, development, recurrence and metastasis of cancer are closely related to inflammation, which is a kind of defensive response of human body to various stimuli. As an important medicinal plant in Africa, Warburgia ugandensis has been reported to have certain anti-inflammatory and anti-proliferative activities, but its specific components and mechanisms of action remain elusive. To tackle this challenge, affinity ultrafiltration with drug targets of interest coupled to high-performance liquid chromatography-mass spectrometry (AUF-HPLC-MS/MS) could be utilized to quickly screen out bioactive constituents as ligands against target enzymes from complex extracts of this plant. AUF-HPLC-MS/MS with four drug targets, i.e., cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), topoisomerase I (Top I) and topoisomerase II (Top II) were used to rapidly screen and characterize the anti-inflammatory and anti-proliferative natural ligands from W. ugandensis, and the resulting potential active compounds as ligands with specific binding affinity to COX-2, 5-LOX, Top I and Top II, were isolated with modern separation and purification techniques and identified with spectroscopic method like NMR, and then their antiinflammatory and anti-proliferative activities were tested to verify the screening results from AUF-HPLC-MS/MS. Compounds 1 and 2, which screened out and identified from W. ugandensis showed remarkable binding affinity to COX-2, 5-LOX, Top I and Top II with AUF-HPLC-MS/MS. In addition, 1 new compound (compound 3), together with 5 known compounds were also isolated and identified from W. ugandensis. The structure of compound 3 was elucidated by extensive 1D, 2D NMR data and UPLC-QTOF-MS/MS. Furthermore, compounds 1 and 2 were further proved to possess both anti-inflammatory and anti-proliferative activities which are in good agreement with the screening results using AUF-HPLC-MS/MS. This work showcased an efficient method for quickly screening out bioactive components with anti-inflammatory and anti-proliferative activity from complex medicinal plant extracts using AUF-HPLC-MS/MS with target enzymes of interest, and also demonstrated that neolignanamides (compounds 1 and 2) from W. ugandensis would be the active components responsible for its anti-inflammatory and anti-proliferative activity with the potential to treat cancer and inflammation.

A focus on the biological targets for coinage metal-NHCs as potential anticancer complexes

Metal complexes of N-heterocyclic carbene (NHC) ligands are the object of increasing attention for therapeutic purposes. Among the different metal centres, interest on Au-based compounds started with the application as anti-arthritis drugs. On the other hand, Ag(I) antimicrobial properties have been known for a long time. For Au(I)/Au(III)-NHC and Ag(I)-NHC anti-tumour and anti-proliferative properties have been quite recently demonstrated. In addition to these and as for Group 11, copper is a much less investigated metal centre, but a few papers underline its pharmacological potential. This review wants to focus on the different biological targets for these metal-based compounds. It is divided into chapters which are respectively devoted on: i) mitochondria and thiol oxidoreductase systems; ii) other relevant enzymes; iii) nucleic acids. Examples of representative coinage NHCs for each of the targets are provided together with significant references on recent advances on the topic. Moreover, a final comment summarises the aspects enlightened by each chapter and provides some hints to better understand the metal-NHCs mechanistic behaviour based on structure-activity relationships.