Topoisomerase inhibitors: Pharmacology and emerging nanoscale delivery systems

Copper and Copper Complexes in Tumor Therapy

Copper (Cu), a crucial trace element in physiological processes, has garnered significant interest for its involvement in cancer progression and potential therapeutic applications. The regulation of cellular copper levels is essential for maintaining copper homeostasis, as imbalances can lead to toxicity and cell death. The development of drugs that target copper homeostasis has emerged as a promising strategy for anticancer treatment, with a particular focus on copper chelators, copper ionophores, and novel copper complexes. Recent research has also investigated the potential of copper complexes in cancer therapy.

A comparative study of novel ruthenium(III) and iron(III) complexes containing uracil; docking and biological studies

Structural and biological studies were conducted on the novel complexes [Fe(U)2(H2O)2]Cl3 (FeU) and [Ru(U)2(H2O)2]Cl3 (RuU) (U = 5,6-Diamino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione) to develop an anticancer drug candidate. The two complexes have been synthesized and characterized. Based on our findings, these complexes have octahedral geometry. The DNA-binding study proved that both complexes coordinated with CT-DNA. The docking study confirmed the potency of both complexes in downregulating the topoisomerase I protein through their high binding affinity. Biological studies have established that both complexes can act as potent anticancer agents against three cancer cell lines. RuU or FeU complexes induce apoptosis in breast cancer cells by increasing caspase9 protein and inhibiting proliferating cell nuclear antigen (PCNA) activity. In addition, both complexes down-regulate topoisomerase I expression in breast cancer cells. Therefore, the RuU and FeU complexes' anticancer activities were mediated via both apoptosis induction and topoisomerase I down-regulation. In conclusion, both complexes have dual anticancer activity pathways that may be responsible for the selective cytotoxicity of the complexes. This makes them more suitable for the development of novel cancer treatment strategies.

Lipid-Based Delivery Systems for Flavonoids and Flavonolignans: Liposomes, Nanoemulsions, and Solid Lipid Nanoparticles

Herbal chemicals with a long history in medicine have attracted a lot of attention. Flavonolignans and flavonoids are considered as two classes of the above-mentioned compounds with different functional groups which exhibit several therapeutic capabilities such as antimicrobial, anti-inflammatory, antioxidant, antidiabetic, and anticancer activities. Based on the studies, high hydrophobic properties of the aforementioned compounds limit their bioavailability inside the human body and restrict their wide application. Nanoscale formulations such as solid lipid nanoparticles, liposomes, and other types of lipid-based delivery systems have been introduced to overcome the above-mentioned challenges. This approach allows the aforementioned hydrophobic therapeutic compounds to be encapsulated between hydrophobic structures, resulting in improving their bioavailability. The above-mentioned enhanced delivery system improves delivery to the targeted sites and reduces the daily required dosage. Lowering the required daily dose improves the performance of the drug by diminishing its side effects on non-targeted tissues. The present study aims to highlight the recent improvements in implementing lipid-based nanocarriers to deliver flavonolignans and flavonoids.

Next-Generation Hydrogels as Biomaterials for Biomedical Applications: Exploring the Role of Curcumin

Since the first report on the pharmacological activity of curcumin in 1949, enormous amounts of research have reported diverse activities for this natural polyphenol found in the dietary spice turmeric. However, curcumin has not yet been used for human application as an approved drug. The clinical translation of curcumin has been hampered due to its low solubility and bioavailability. The improvement in bioavailability and solubility of curcumin can be achieved by its formulation using drug delivery systems. Hydrogels with their biocompatibility and low toxicity effects have shown a substantial impact on the successful formulation of hydrophobic drugs for human clinical trials. This review focuses on hydrogel-based delivery systems for curcumin and describes its applications as anti-cancer as well as wound healing agents.

Apoptotic Mechanisms of Quercetin in Liver Cancer: Recent Trends and Advancements

Due to rising incidence rates of liver cancer and worries about the toxicity of current chemotherapeutic medicines, the hunt for further alternative methods to treat this malignancy has escalated. Compared to chemotherapy, quercetin, a flavonoid, is relatively less harmful to normal cells and is regarded as an excellent free-radical scavenger. Apoptotic cell death of cancer cells caused by quercetin has been demonstrated by many prior studies. It is present in many fruits, vegetables, and herbs. Quercetin targets apoptosis, by upregulating Bax, caspase-3, and p21 while downregulating Akt, PLK-1, cyclin-B1, cyclin-A, CDC-2, CDK-2, and Bcl-2. Additionally, it has been reported to increase STAT3 protein degradation in liver cancer cells while decreasing STAT3 activation. Quercetin has a potential future in chemoprevention, based on substantial research on its anticancer effects. The current review discusses quercetin's mechanisms of action, nanodelivery strategies, and other potential cellular effects in liver cancer.

Biological impact and therapeutic perspective of targeting PI3K/Akt signaling in hepatocellular carcinoma: Promises and Challenges

Cancer progression results from activation of various signaling networks. Among these, PI3K/Akt signaling contributes to proliferation, invasion, and inhibition of apoptosis. Hepatocellular carcinoma (HCC) is a primary liver cancer with high incidence rate, especially in regions with high prevalence of viral hepatitis infection. Autoimmune disorders, diabetes mellitus, obesity, alcohol consumption, and inflammation can also lead to initiation and development of HCC. The treatment of HCC depends on the identification of oncogenic factors that lead tumor cells to develop resistance to therapy. The present review article focuses on the role of PI3K/Akt signaling in HCC progression. Activation of PI3K/Akt signaling promotes glucose uptake, favors glycolysis and increases tumor cell proliferation. It inhibits both apoptosis and autophagy while promoting HCC cell survival. PI3K/Akt stimulates epithelial-to-mesenchymal transition (EMT) and increases matrix-metalloproteinase (MMP) expression during HCC metastasis. In addition to increasing colony formation capacity and facilitating the spread of tumor cells, PI3K/Akt signaling stimulates angiogenesis. Therefore, silencing PI3K/Akt signaling prevents aggressive HCC cell behavior. Activation of PI3K/Akt signaling can confer drug resistance, particularly to sorafenib, and decreases the radio-sensitivity of HCC cells. Anti-cancer agents, like phytochemicals and small molecules can suppress PI3K/Akt signaling by limiting HCC progression. Being upregulated in tumor tissues and clinical samples, PI3K/Akt can also be used as a biomarker to predict patients' response to therapy.

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.

Cucurbitacins as Potent Chemo-Preventive Agents: Mechanistic Insight and Recent Trends

Cucurbitacins constitute a group of cucumber-derived dietary lipids, highly oxidized tetracyclic triterpenoids, with potential medical uses. These compounds are known to interact with a variety of recognized cellular targets to impede the growth of cancer cells. Accumulating evidence has suggested that inhibition of tumor cell growth via induction of apoptosis, cell-cycle arrest, anti-metastasis and anti-angiogenesis are major promising chemo-preventive actions of cucurbitacins. Cucurbitacins may be a potential choice for investigations of synergism with other drugs to reverse cancer cells' treatment resistance. The detailed molecular mechanisms underlying these effects include interactions between cucurbitacins and numerous cellular targets (Bcl-2/Bax, caspases, STAT3, cyclins, NF-κB, COX-2, MMP-9, VEGF/R, etc.) as well as control of a variety of intracellular signal transduction pathways. The current study is focused on the efforts undertaken to find possible molecular targets for cucurbitacins in suppressing diverse malignant processes. The review is distinctive since it presents all potential molecular targets of cucurbitacins in cancer on one common podium.

Nanoplatform for the Delivery of Topotecan in the Cancer Milieu: An Appraisal of its Therapeutic Efficacy

Chemotherapy has been the predominant treatment modality for cancer patients, but its overall performance is still modest. Difficulty in penetration of tumor tissues, a toxic profile in high doses, multidrug resistance in an array of tumor types, and the differential architecture of tumor cells as they grow are some of the bottlenecks associated with the clinical usage of chemotherapeutics. Recent advances in tumor biology understanding and the emergence of novel targeted drug delivery tools leveraging various nanosystems offer hope for developing effective cancer treatments. Topotecan is a topoisomerase I inhibitor that stabilizes the transient TOPO I-DNA cleavable complex, leading to single-stranded breaks in DNA. Due to its novel mechanism of action, TOPO is reported to be active against various carcinomas, namely small cell lung cancer, cervical cancer, breast cancer, and ovarian cancer. Issues of cross-resistance with numerous drugs, rapid conversion to its inactive form in biological systems, appended adverse effects, and higher water solubility limit its therapeutic efficacy in clinical settings. Topotecan nanoformulations offer several benefits for enhancing the therapeutic action of this significant class of chemotherapeutics. The likelihood that the target cancer cells will be exposed to the chemotherapeutic drug while in the drug-sensitive s-phase is increased due to the slow and sustained release of the chemotherapeutic, which could provide for a sustained duration of exposure of the target cancer cells to the bioavailable drug and result in the desired therapeutic outcome. This article explores nanoenabled active and passive targeting strategies and combinatorial therapy employing topotecan to ameliorate various cancers, along with a glimpse of the clinical studies utilizing the said molecule.

Canvassing Prospects of Glyco-Nanovaccines for Developing Cross-Presentation Mediated Anti-Tumor Immunotherapy

In view of the severe downsides of conventional cancer therapies, the quest of developing alternative strategies still remains of critical importance. In this regard, antigen cross-presentation, usually employed by dendritic cells (DCs), has been recognized as a potential solution to overcome the present impasse in anti-cancer therapeutic strategies. It has been established that an elevated cytotoxic T lymphocyte (CTL) response against cancer cells can be achieved by targeting receptors expressed on DCs with specific ligands. Glycans are known to serve as ligands for C-type lectin receptors (CLRs) expressed on DCs, and are also known to act as a tumor-associated antigen (TAA), and, thus, can be harnessed as a potential immunotherapeutic target. In this scenario, integrating the knowledge of cross-presentation and glycan-conjugated nanovaccines can help us to develop so called 'glyco-nanovaccines' (GNVs) for targeting DCs. Here, we briefly review and analyze the potential of GNVs as the next-generation anti-tumor immunotherapy. We have compared different antigen-presenting cells (APCs) for their ability to cross-present antigens and described the potential nanocarriers for tumor antigen cross-presentation. Further, we discuss the role of glycans in targeting of DCs, the immune response due to pathogens, and imitative approaches, along with parameters, strategies, and challenges involved in cross-presentation-based GNVs for cancer immunotherapy. It is known that the effectiveness of GNVs in eradicating tumors by inducing strong CTL response in the tumor microenvironment (TME) has been largely hindered by tumor glycosylation and the expression of different lectin receptors (such as galectins) by cancer cells. Tumor glycan signatures can be sensed by a variety of lectins expressed on immune cells and mediate the immune suppression which, in turn, facilitates immune evasion. Therefore, a sound understanding of the glycan language of cancer cells, and glycan-lectin interaction between the cancer cells and immune cells, would help in strategically designing the next-generation GNVs for anti-tumor immunotherapy.

Licorice (Glycyrrhiza glabra L.)-Derived Phytochemicals Target Multiple Signaling Pathways to Confer Oncopreventive and Oncotherapeutic Effects

Cancer is a highly lethal disease, and its incidence has rapidly increased worldwide over the past few decades. Although chemotherapeutics and surgery are widely used in clinical settings, they are often insufficient to provide the cure for cancer patients. Hence, more effective treatment options are highly needed. Although licorice has been used as a medicinal herb since ancient times, the knowledge about molecular mechanisms behind its diverse bioactivities is still rather new. In this review article, different anticancer properties (antiproliferative, antiangiogenic, antimetastatic, antioxidant, and anti-inflammatory effects) of various bioactive constituents of licorice (Glycyrrhiza glabra L.) are thoroughly described. Multiple licorice constituents have been shown to bind to and inhibit the activities of various cellular targets, including B-cell lymphoma 2, cyclin-dependent kinase 2, phosphatidylinositol 3-kinase, c-Jun N-terminal kinases, mammalian target of rapamycin, nuclear factor-κB, signal transducer and activator of transcription 3, vascular endothelial growth factor, and matrix metalloproteinase-3, resulting in reduced carcinogenesis in several in vitro and in vivo models with no evident toxicity. Emerging evidence is bringing forth licorice as an anticancer agent as well as bottlenecks in its potential clinical application. It is expected that overcoming toxicity-related obstacles by using novel nanotechnological methods might importantly facilitate the use of anticancer properties of licorice-derived phytochemicals in the future. Therefore, anticancer studies with licorice components must be continued. Overall, licorice could be a natural alternative to the present medication for eradicating new emergent illnesses while having just minor side effects.

Synthesis of novel amidines via one-pot three component reactions: Selective topoisomerase I inhibitors with antiproliferative properties

Novel series of amidines were synthesized via the interaction between alicyclic amines, cyclic ketones, and a highly electrophilic 4-azidoquinolin-2(1H)-ones without any catalyst or additive. All the obtained products were elucidated based on NMR spectroscopy, mass spectrometry, and elemental analysis. The reaction conditions were optimized using cyclohexanone (2), piperidine (3a), and 4-azido-quinolin-2(1H)-one (1a) under an air atmosphere. The new compounds 4a-l and 5a-c were tested for antiproliferative activity against four cancer cell lines using doxorubicin as a reference drug. The most potent derivatives were compounds 4b, 4d, 4e, 4i, and 5c, with GI50 ranging from 1.00 µM to 1.50 µM. Compound 5c was the most effective derivative against the four cancer cell lines, outperforming doxorubicin. The compounds 4b, 4d, 4e, 4i, and 5c were studied further as topoisomerase I and IIα inhibitors. The compounds tested showed selective inhibition of topo I over topo IIα. Finally, docking studies explain why these compounds prefer topo I over topo IIα.

In Vitro and in Silico Investigation of DNA Interaction, Topoisomerase I and II Inhibitory Properties of Polydatin

Polydatin or piceid, is the 3-O-glucoside of resveratrol and is found abundantly in grapes, peanuts, wine, beer, and cacao products. Although anticancer activity of polydatin was reported before, and potential antiproliferative mechanisms of polydatin have been proposed, its direct effects on DNA and inhibitory potential against topoisomerase enzymes have remained unknown. In this study we aimed to reveal the link between polydatin's effects on DNA and DNA-topoisomerases and its antiproliferative promise. For this purpose, we evaluated the effects of polydatin on DNA and DNA topoisomerase using in vitro and in silico techniques. Polydatin was found to protect DNA against Fenton reaction-induced damage while not showing any hydrolytic nuclease effect. Further, polydatin inhibited topoisomerase II but not topoisomerase I. According to molecular docking studies, polydatin preferably showed minor groove binding to DNA where the stilbene moiety was important for binding to the DNA-topoisomerase II complex. As a result, topoisomerase II inhibition might be another anticancer mechanism of polydatin.

Curcumin in the treatment of urological cancers: Therapeutic targets, challenges and prospects

Urological cancers include bladder, prostate and renal cancers that can cause death in males and females. Patients with urological cancers are mainly diagnosed at an advanced disease stage when they also develop resistance to therapy or poor response. The use of natural products in the treatment of urological cancers has shown a significant increase. Curcumin has been widely used in cancer treatment due to its ability to trigger cell death and suppress metastasis. The beneficial effects of curcumin in the treatment of urological cancers is the focus of current review. Curcumin can induce apoptosis in the three types of urological cancers limiting their proliferative potential. Furthermore, curcumin can suppress invasion of urological cancers through EMT inhibition. Notably, curcumin decreases the expression of MMPs, therefore interfering with urological cancer metastasis. When used in combination with chemotherapy agents, curcumin displays synergistic effects in suppressing cancer progression. It can also be used as a chemosensitizer. Based on pre-clinical studies, curcumin administration is beneficial in the treatment of urological cancers and future clinical applications might be considered upon solving problems related to the poor bioavailability of the compound. To improve the bioavailability of curcumin and increase its therapeutic index in urological cancer suppression, nanostructures have been developed to favor targeted delivery.

Chitosan-based nanoscale systems for doxorubicin delivery: Exploring biomedical application in cancer therapy

Green chemistry has been a growing multidisciplinary field in recent years showing great promise in biomedical applications, especially for cancer therapy. Chitosan (CS) is an abundant biopolymer derived from chitin and is present in insects and fungi. This polysaccharide has favorable characteristics, including biocompatibility, biodegradability, and ease of modification by enzymes and chemicals. CS-based nanoparticles (CS-NPs) have shown potential in the treatment of cancer and other diseases, affording targeted delivery and overcoming drug resistance. The current review emphasizes on the application of CS-NPs for the delivery of a chemotherapeutic agent, doxorubicin (DOX), in cancer therapy as they promote internalization of DOX in cancer cells and prevent the activity of P-glycoprotein (P-gp) to reverse drug resistance. These nanoarchitectures can provide co-delivery of DOX with antitumor agents such as curcumin and cisplatin to induce synergistic cancer therapy. Furthermore, co-loading of DOX with siRNA, shRNA, and miRNA can suppress tumor progression and provide chemosensitivity. Various nanostructures, including lipid-, carbon-, polymeric- and metal-based nanoparticles, are modifiable with CS for DOX delivery, while functionalization of CS-NPs with ligands such as hyaluronic acid promotes selectivity toward tumor cells and prevents DOX resistance. The CS-NPs demonstrate high encapsulation efficiency and due to protonation of amine groups of CS, pH-sensitive release of DOX can occur. Furthermore, redox- and light-responsive CS-NPs have been prepared for DOX delivery in cancer treatment. Leveraging these characteristics and in view of the biocompatibility of CS-NPs, we expect to soon see significant progress towards clinical translation.

Topoisomerase IIA in adult NSCs regulates SVZ neurogenesis by transcriptional activation of Usp37

Topoisomerase IIA (TOP2a) has traditionally been known as an important nuclear enzyme that resolves entanglements and relieves torsional stress of DNA double strands. However, its function in genomic transcriptional regulation remains largely unknown, especially during adult neurogenesis. Here, we show that TOP2a is preferentially expressed in neurogenic niches in the brain of adult mice, such as the subventricular zone (SVZ). Conditional knockout of Top2a in adult neural stem cells (NSCs) of the SVZ significantly inhibits their self-renewal and proliferation, and ultimately reduces neurogenesis. To gain insight into the molecular mechanisms by which TOP2a regulates adult NSCs, we perform RNA-sequencing (RNA-Seq) plus chromatin immunoprecipitation sequencing (ChIP-Seq) and identify ubiquitin-specific protease 37 (Usp37) as a direct TOP2a target gene. Importantly, overexpression of Usp37 is sufficient to rescue the impaired self-renewal ability of adult NSCs caused by Top2a knockdown. Taken together, this proof-of-principle study illustrates a TOP2a/Usp37-mediated novel molecular mechanism in adult neurogenesis, which will significantly expand our understanding of the function of topoisomerase in the adult brain.

Chemotherapy reinforces anti-tumor immune response and enhances clinical efficacy of immune checkpoint inhibitors

New evidence suggests that the clinical success of chemotherapy is not merely due to tumor cell toxicity but also arises from the restoration of immunosurveillance, which has been immensely neglected in previous preclinical and clinical researches. There is an urgent need for novel insights into molecular mechanisms and regimens that uplift the efficacy of immunotherapy since only a minority of cancer patients are responsive to immune checkpoint inhibitors (ICIs). Recent findings on combination therapy of chemotherapy and ICIs have shown promising results. This strategy increases tumor recognition and elimination by the host immune system while reducing immunosuppression by the tumor microenvironment. Currently, several preclinical studies are investigating molecular mechanisms that give rise to the immunomodulation by chemotherapeutic agents and exploit them in combination therapy with ICIs in order to achieve a synergistic clinical activity. In this review, we summarize studies that exhibit the capacity of conventional chemotherapeutics to elicit anti-tumor immune responses, thereby facilitating anti-tumor activities of the ICIs. In conclusion, combining chemotherapeutics with ICIs appears to be a promising approach for improving cancer treatment outcomes.

Dexamethasone: Insights into Pharmacological Aspects, Therapeutic Mechanisms, and Delivery Systems

Dexamethasone (DEX) has been widely used to treat a variety of diseases, including autoimmune diseases, allergies, ocular disorders, cancer, and, more recently, COVID-19. However, DEX usage is often restricted in the clinic due to its poor water solubility. When administered through a systemic route, it can elicit severe side effects, such as hypertension, peptic ulcers, hyperglycemia, and hydro-electrolytic disorders. There is currently much interest in developing efficient DEX-loaded nanoformulations that ameliorate adverse disease effects inhibiting advancements in scientific research. Various nanoparticles have been developed to selectively deliver drugs without destroying healthy cells or organs in recent years. In the present review, we have summarized some of the most attractive applications of DEX-loaded delivery systems, including liposomes, polymers, hydrogels, nanofibers, silica, calcium phosphate, and hydroxyapatite. This review provides our readers with a broad spectrum of nanomedicine approaches to deliver DEX safely.

Stereoselective Synthesis and Anticancer Activity of 2,6-Disubstituted trans-3-Methylidenetetrahydropyran-4-ones

In this report, we present efficient and stereoselective syntheses of 2,6-disubstituted trans-3-methylidenetetrahydropyran-4-ones and 2-(4-methoxyphenyl)-5-methylidenetetrahydropyran-4-one that significantly broaden the spectrum of the available methylidenetetrahydropyran-4-ones with various substitution patterns. Target compounds were obtained using Horner–Wadsworth–Emmons methodology for the introduction of methylidene group onto the pyranone ring. 3-Diethoxyphosphoryltetrahydropyran-4-ones, which were key intermediates in this synthesis, were prepared by fully or highly stereoselective addition of Gilman or Grignard reagents to 3-diethoxyphosphoryldihydropyran-4-ones. Addition occurred preferentially by axial attack of the Michael donors on the dihydropyranone ring. Relative configurations and conformations of the obtained adducts were assigned using a detailed analysis of the NMR spectra. The obtained methylidenepyran-4-ones were evaluated for cytotoxic activity against two cancer cell lines (HL-60 and MCF-7). 2,6-Disubstituted 3-methylidenetetrahydropyran-4-ones with isopropyl and phenyl substituents in position 2 were more cytotoxic than analogs with n-butyl substituent. Two of the most cytotoxic analogs were then selected for further investigation on the HL-60 cell line. Both analogs induced morphological changes characteristic of apoptosis in cancer cells, significantly inhibited proliferation and induced apoptotic cell death. Both compounds also generated DNA damage, and one of the analogs arrested the cell cycle of HL-60 cells in the G2/M phase. In addition, both analogs were able to inhibit the activity of topoisomerase IIα. Based on these findings, the investigated analogs may be further optimized for the development of new and effective topoisomerase II inhibitors.

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.

Doxorubicin-loaded graphene oxide nanocomposites in cancer medicine: Stimuli-responsive carriers, co-delivery and suppressing resistance

INTRODUCTION

The application of doxorubicin (DOX) in cancer therapy has been limited due to its drug resistance and poor internalization. Graphene oxide (GO) nanostructures have the capacity for DOX delivery while promoting its cytotoxicity in cancer.

AREAS COVERED

The favorable characteristics of GO nanocomposites, preparation method, and application in cancer therapy are described. Then, DOX resistance in cancer is discussed. The GO-mediated photothermal therapy and DOX delivery for cancer suppression are described. Preparation of stimuli-responsive GO nanocomposites, surface functionalization, hybrid nanoparticles, and theranostic applications are emphasized in DOX chemotherapy.

EXPERT OPINION

Graphene oxide nanoparticle-based photothermal therapy maximizes the anti-cancer activity of DOX against cancer cells. Apart from DOX delivery, GO nanomaterials are capable of loading anti-cancer agents and genetic tools to minimize drug resistance and enhance the cytolytic impact of DOX in cancer eradication. To enhance DOX accumulation in cancer cells, stimuli-responsive (redox-, light-, enzyme- and pH-sensitive) GO nanoparticles have been developed for DOX delivery. Further development of targeted delivery of DOX-loaded GO nanomaterials against cancer cells may be achieved by surface modification of polymers such as polyethylene glycol, hyaluronic acid, and chitosan. Doxorubicin-loaded GO nanoparticles have demonstrated theranostic potential for simultaneous diagnosis and therapy. Hybridization of GO with other nanocarriers such as silica and gold nanoparticles further broadens their potential anti-cancer therapy applications.

The multifaceted antineoplastic role of pyrimethamine against different human malignancies

Cancer accounted for nearly 10 million deaths in 2020 and is the second leading cause of death worldwide. The chemotherapeutic agents that are in clinical practice possess a broad range of severe adverse effects towards vital organs which emphasizes the importance of the discovery of new therapeutic agents or repurposing of existing drugs for the treatment of human cancers. Pyrimethamine is an antiparasitic drug used for the treatment of malaria and toxoplasmosis with a well-documented excellent safety profile. In the last five years, numerous efforts have been made to explore the anticancer potential of pyrimethamine in in vitro and in vivo preclinical models and to repurpose it as an anticancer agent. The studies have demonstrated that pyrimethamine inhibits oncogenic proteins such as STAT3, NF-κB, DX2, MAPK, DHFR, thymidine phosphorylase, telomerase, and many more in a different types of cancer models. Moreover, pyrimethamine has been reported to work in synergy with other anticancer agents, such as temozolomide, to induce apoptosis of tumor cells. Recently, the results of phase-1/2 clinical trials demonstrated that pyrimethamine administration reduces the expression of STAT3 signature genes in tumor tissues of chronic lymphocytic leukemia patients with a good therapeutic response. In the present article, we have reviewed most of the published papers related to the antitumor effects of pyrimethamine in malignancies of breast, liver, lung, skin, ovary, prostate, pituitary, and leukemia in in vitro and in vivo settings. We have also discussed the pharmacokinetic profile and results of clinical trials obtained after pyrimethamine treatment. From these studies, we believe that pyrimethamine has the potential to be repurposed as an anticancer drug. This article is protected by copyright. All rights reserved.

Chitosan: A versatile bio-platform for breast cancer theranostics

Breast cancer is considered one of the utmost neoplastic diseases globally, with a high death rate of patients. Over the last decades, many approaches have been studied to early diagnose and treat it, such as chemotherapy, hormone therapy, immunotherapy, and MRI and biomarker tests; do not show the optimal efficacy. These existing approaches are accompanied by severe side effects, thus recognizing these challenges, a great effort has been done to find out the new remedies for breast cancer. Main finding: Nanotechnology opened a new horizon to the treatment of breast cancer. Many nanoparticulate platforms for the diagnosis of involved biomarkers and delivering antineoplastic drugs are under either clinical trials or just approved by the Food and Drug Administration (FDA). It is well known that natural phytochemicals are successfully useful to treat breast cancer because these natural compounds are safer, available, cheaper, and have less toxic effects. Chitosan is a biocompatible and biodegradable polymer. Further, it has outstanding features, like chemical functional groups that can easily modify our interest with an exceptional choice of promising applications. Abundant studies were directed to assess the chitosan derivative-based nanoformulation's abilities in delivering varieties of drugs. However, the role of chitosan in diagnostics and theranostics not be obligated. The present servey will discuss the application of chitosan as an anticancer drug carrier such as tamoxifen, doxorubicin, paclitaxel, docetaxel, etc. and also, its role as a theranostics (i.e. photo-responsive and thermo-responsive) moieties. The therapeutic and theranostic potential of chitosan in cancer is promising and it seems that to have a good potential to get to the clinic.

Photodynamic therapy for leishmaniasis: Recent advances and future trends

Leishmaniasis has infected more than 12 million people worldwide. This neglected tropical disease, causing 20,000-30,000 deaths per year, is a global health problem. The emergence of resistant parasites and serious side effects of conventional therapies has led to the search for less toxic and non-invasive alternative treatments. Photodynamic therapy is a promising therapeutic strategy to produce reactive oxygen species for the treatment of leishmaniasis. In this regard, natural and synthetic photosensitizers such as curcumin, hypericin, 5-aminolevulinic acid, phthalocyanines, phenothiazines, porphyrins, chlorins and nanoparticles have been applied. In this review, the recent advances on using photodynamic therapy for treating Leishmania species have been reviewed.

Targeting Cancer Stem Cells by Dietary Agents: An Important Therapeutic Strategy against Human Malignancies

As a multifactorial disease, treatment of cancer depends on understanding unique mechanisms involved in its progression. The cancer stem cells (CSCs) are responsible for tumor stemness and by enhancing colony formation, proliferation as well as metastasis, and these cells can also mediate resistance to therapy. Furthermore, the presence of CSCs leads to cancer recurrence and therefore their complete eradication can have immense therapeutic benefits. The present review focuses on targeting CSCs by natural products in cancer therapy. The growth and colony formation capacities of CSCs have been reported can be attenuated by the dietary agents. These compounds can induce apoptosis in CSCs and reduce tumor migration and invasion via EMT inhibition. A variety of molecular pathways including STAT3, Wnt/β-catenin, Sonic Hedgehog, Gli1 and NF-κB undergo down-regulation by dietary agents in suppressing CSC features. Upon exposure to natural agents, a significant decrease occurs in levels of CSC markers including CD44, CD133, ALDH1, Oct4 and Nanog to impair cancer stemness. Furthermore, CSC suppression by dietary agents can enhance sensitivity of tumors to chemotherapy and radiotherapy. In addition to in vitro studies, as well as experiments on the different preclinical models have shown capacity of natural products in suppressing cancer stemness. Furthermore, use of nanostructures for improving therapeutic impact of dietary agents is recommended to rapidly translate preclinical findings for clinical use.

Editing SOX Genes by CRISPR-Cas: Current Insights and Future Perspectives

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and its associated proteins (Cas) is an adaptive immune system in archaea and most bacteria. By repurposing these systems for use in eukaryote cells, a substantial revolution has arisen in the genome engineering field. In recent years, CRISPR-Cas technology was rapidly developed and different types of DNA or RNA sequence editors, gene activator or repressor, and epigenome modulators established. The versatility and feasibility of CRISPR-Cas technology has introduced this system as the most suitable tool for discovering and studying the mechanism of specific genes and also for generating appropriate cell and animal models. SOX genes play crucial roles in development processes and stemness. To elucidate the exact roles of SOX factors and their partners in tissue hemostasis and cell regeneration, generating appropriate in vitro and in vivo models is crucial. In line with these premises, CRISPR-Cas technology is a promising tool for studying different family members of SOX transcription factors. In this review, we aim to highlight the importance of CRISPR-Cas and summarize the applications of this novel, promising technology in studying and decoding the function of different members of the SOX gene family.

Anthracycline Associated Disturbances of Cardiovascular Homeostasis

Despite the dynamic progress of modern medicine, oncological and cardiovascular diseases (CVD) remain a severe economic burden worldwide. Therefore, the study of chemotherapeutic cardiotoxicity appears to be comprehensively demanded. Nowadays, pharmacological therapy in oncology has undoubtedly unprecedented development, but at the same time, the rates of cardiovascular complications of chemotherapy still remain unchanged. The well-established and highly effective, but at the same time, cardiotoxic anthracyclines have not lost their relevance. Furthermore, they remain indispensable components of an immense amount of chemotherapy regimens, such as AC, FAC, etc. Moreover, the anthracycline-containing chemotherapy regimens have become a standard of care in several cancer types. In the context of the above mentioned, the study of the pathophysiological mechanisms, biochemical aspects, and dynamics of the morphological remodeling of doxorubicin-induced cardiovascular homeostasis disturbances will enable finding new targets of pharmacological therapy, which either in the short or long perspectives, will have a beneficial effect, improving both the quality of life and prognosis of oncological patients. This article covers a versatile overview of the molecular mechanisms of doxorubicin-induced cardiotoxicity. The pathogenesis of cardiotoxicity assessment could help to explore specific molecular mechanisms that initiate cardiovascular alteration that may favorably affect the future development of targeted drugs that could prevent cardiovascular events in cancer patients.

Effect of Paclitaxel/etoposide co-loaded polymeric nanoparticles on tumor size and survival rate in a rat model of glioblastoma

The aim of this work is to co-load paclitaxel (PTX) and etoposide (ETP) in methoxy poly(ethylene glycol)-poly(lactic-co-glycolic acid) nanoparticles (mPEG-PLGA NPs) to overcome pharmacokinetics and physiological limitations and enhance therapeutic efficacy for treating intracranial glioblastoma. Both drugs were loaded into mPEG-PLGA NPs by a nano-precipitation method. The resultant NPs demonstrated an enhanced cytotoxic effect indicated by lower IC₅₀ values and augmented cell apoptosis to U87 and C6 glioma cell lines compared to both free drugs. Additionally, blood compatibility assays showed that the PTX/ETP co-loaded mPEG-PLGA NPs did not induce blood hemolysis, blood clotting, or platelet aggregation. In vivo anti-glioma efficacy evaluation in rats bearingintracranialC6glioma revealed a superior anti-glioma activity for the treatment with PTX/ETP co-loaded mPEG-PLGA NPs compared to other formulations, particularly a significantly longer median survival, 76 days compared to 36 days for free PTX and 37 days for free ETP treatment, respectively, and higher tumor regression, proved by magnetic resonance imaging (MRI).

Explainable artificial intelligence in high-throughput drug repositioning for subgroup stratifications with interventionable potential

Enabling precision medicine requires developing robust patient stratification methods as well as drugs tailored to homogeneous subgroups of patients from a heterogeneous population. Developing de novo drugs is expensive and time consuming with an ultimately low FDA approval rate. These limitations make developing new drugs for a small portion of a disease population unfeasible. Therefore, drug repositioning is an essential alternative for developing new drugs for a disease subpopulation. This shows the importance of developing data-driven approaches that find druggable homogeneous subgroups within the disease population and reposition the drugs for these subgroups. In this study, we developed an explainable AI approach for patient stratification and drug repositioning. Contrast pattern mining and network analysis were used to discover homogeneous subgroups within a disease population. For each subgroup, a biomedical network analysis was done to find the drugs that are most relevant to a given subgroup of patients. The set of candidate drugs for each subgroup was ranked using an aggregated drug score assigned to each drug. The proposed method represents a human-in-the-loop framework, where medical experts use the data-driven results to generate hypotheses and obtain insights into potential therapeutic candidates for patients who belong to a subgroup. Colorectal cancer (CRC) was used as a case study. Patients' phenotypic and genotypic data was utilized with a heterogeneous knowledge base because it gives a multi-view perspective for finding new indications for drugs outside of their original use. Our analysis of the top candidate drugs for the subgroups identified by medical experts showed that most of these drugs are cancer-related, and most of them have the potential to be a CRC regimen based on studies in the literature.

Synthesis, molecular modeling and biological evaluation of new benzo[4,5]thieno[3,2-b]pyran derivatives as topoisomerase I-DNA binary complex poisons

A series of new benzo[b]thiophenes 2a-f and benzo[4,5]thieno[3,2-b]pyran derivatives 3a-f and 4a-f were synthesized and their structures were confirmed by elemental analyses and spectral data. All synthesized compounds were evaluated by the National Cancer Institute (NCI, USA) against 60 human tumor cell lines. Compounds 3a-f and 4a-f showed potent cytotoxic effects in one dose assay with mean growth inhibition ranging from 62% to 80%. Six compounds 3a, 3d, 3e, 3f, 4d and 4e were selected by NCI, USA for five dose evaluation against 60 human tumor cell lines. Compounds 3a, 3d, 3e and 3f exhibited very potent and broad spectrum cytotoxicity against almost all cancer cell lines with mean concentration that yield 50% growth inhibition (MG-MID GI₅₀) of 0.1-0.58 µM and mean concentration that produce 100% growth inhibition (MG-MID TGI) of 6.03-10.00 µM. Compounds 4d and 4e exhibited very potent and selective cytotoxic activity against MDA-MB-435 subpanel (melanoma cancer) with GI₅₀ of 0.45 µM and 0.59 µM, respectively. The mechanism of antiproliferative activity was determined for the most active compounds 3a, 3d, 3e, 3f, 4d, and 4evia measuring their half maximal inhibitory concentration (IC₅₀) against topoisomerase I enzyme at different concentrations. Compounds 3a and 3e exhibited excellent activity compared with reference drugs with IC₅₀ of 0.295 µM and 0.219 µM, respectively. Plasmid DNA nicking assay verified that these compounds are topoisomerase I poisons not suppressors. The active compound 3e induced a significant disruption in the cell cycle profile parallel to its effect on apoptosis induction.

New Horizons in Hydrogels for Methotrexate Delivery

Since its first clinical application, methotrexate (MTX) has been widely used for the treatment of human diseases. Despite great advantages, some properties such as poor absorption, short plasma half-life and unpredictable bioavailability have led researchers to seek novel delivery systems to improve its characteristics for parenteral and oral administration. Recently, great attention has been directed to hydrogels for the preparation of MTX formulations. This review describes the potential of hydrogels for the formulation of MTX to treat cancer, rheumatoid arthritis, psoriasis and central nervous system diseases. We will delineate the state-of-the-art and promising potential of hydrogels for systemic MTX delivery as well as transdermal delivery of the drug-using hydrogel-based formulations.

In vitro and in silico assessment of DNA interaction, topoisomerase I and II inhibition properties of chrysosplenetin

Chrysosplenetin is a methoxyflavone with reported anti-cancer effect. We tested its cytotoxic effect on the MCF-7 breast cancer cell line, and determined its effect on DNA intercalation and on the activity of topoisomerases I and II. The compound inhibited proliferation MCF-7 with an IC₅₀ value of 0.29 μM. Chrysosplenetin did not initiate plasmid DNA cleavage but, in a concentration-dependent manner, protected plasmid DNA against damage induced by Fenton reagents. Furthermore, it possessed dual Topoisomerase I and II inhibitory properties. Especially, it inhibited topoisomerase II by 83-96% between the range 12.5-100 μM. In the light of these experimental findings, molecular docking studies were performed to understand binding mode, interactions and affinity of chrysosplenetin with DNA, and with topoisomerases I and II. These studies showed that of 4-chromone core and the hydroxyl and methoxy groups important for both intercalation with DNA and topoisomerase I and II inhibition.

FAM122A maintains DNA stability possibly through the regulation of topoisomerase IIα expression

FAM122A is a housekeeping gene and highly conserved in mammals. More recently, we have demonstrated that FAM122A is essential for maintaining the growth of hepatocellular carcinoma cells, in which we unexpectedly found that FAM122A deletion increases γH2AX protein level, suggesting that FAM122A may participate in the regulation of DNA homeostasis or stability. In this study, we continued to investigate the potential role of FAM122A in DNA damage and/or repair. We found that CRISPR/Cas9-mediated FAM122A deletion enhances endogenous DNA damages in cancer cells but not in normal cells, demonstrating a significant increase in γH2AX protein and foci formation of γH2AX and 53BP1, as well as DNA breaks by comet assay. Further, we found that FAM122A deletion greatly increases TOP2α protein level, and significantly and specifically enhances TOP2 poisons (etoposide and doxorubicin)-induced DNA damage effects in cancer cells. Moreover, FAM122A is found to be interacted with TOP2α, instead of TOP2β. However, FAM122A knockout doesn't affect the intracellular ROS levels and the process of DNA repair after removal of etoposide with short-term stimulation, suggesting that FAM122A deletion-enhanced DNA damage does not result from endogenous overproduction of ROS and/or impairment of DNA repair ability. Collectively, our study provides the first demonstration that FAM122A is critical for maintaining DNA stability probably by modulating TOP2α protein, and FAM122A deletion combined with TOP2-targeted drugs may represent a potential novel chemotherapeutic strategy for cancer patients.

Copper Complexes as Anticancer Agents Targeting Topoisomerases I and II

Organometallics, such as copper compounds, are cancer chemotherapeutics used alone or in combination with other drugs. One small group of copper complexes exerts an effective inhibitory action on topoisomerases, which participate in the regulation of DNA topology. Copper complexes inhibitors of topoisomerases 1 and 2 work by different molecular mechanisms, analyzed herein. They allow genesis of DNA breaks after the formation of a ternary complex, or act in a catalytic mode, often display DNA intercalative properties and ROS production, and sometimes display dual effects. These amplified actions have repercussions on the cell cycle checkpoints and death effectors. Copper complexes of topoisomerase inhibitors are analyzed in a broader synthetic view and in the context of cancer cell mutations. Finally, new emerging treatment aspects are depicted to encourage the expansion of this family of highly active anticancer drugs and to expend their use in clinical trials and future cancer therapy.

Synthesis, anticancer evaluation and molecular docking studies of new benzimidazole- 1,3,4-oxadiazole derivatives as human topoisomerase types I poison

In this study, some benzimidazole-oxadiazole derivatives were synthesised and tested for their in vitro anticancer activities on five cancer cell lines, including HeLa, MCF7, A549, HepG2 and C6. Their structures were elucidated by IR, ¹H-NMR, ¹³C-NMR, 2 D-NMR and HRMS spectroscopic methods. Among all screened compounds; 5a, 5b, 5d, 5e, 5k, 5l, 5n and 5o exhibited potent selective cytotoxic activities against various tested cancer cell lines. Especially, compounds 5l and 5n exhibited the most antiproliferative activity than Hoechst 33342 and doxorubicin against HeLa cell line, with IC₅₀ of 0.224 ± 0.011 µM and 0.205 ± 0.010 µM, respectively. Furthermore, these potent lead cytotoxic agents were evaluated in terms of their inhibition potency against Topoisomerase I and it was determined that selected compounds inhibited the Topoisomerase I. Docking studies were performed and probable interactions in the DNA-Topo I enzyme complex was determined.

Curcumin Delivery Mediated by Bio-Based Nanoparticles: A Review

Todays, nano-pharmaceutics is emerging as an important field of science to develop and improve efficacy of different drugs. Although nutraceuticals are currently being utilized in the prevention and treatment of various chronic diseases such as cancers, a number of them have displayed issues associated with their solubility, bioavailability, and bio-degradability. In the present review, we focus on curcumin, an important and widely used polyphenol, with diverse pharmacological activities such as anti-inflammatory, anti-carcinogenic, anti-viral, etc. Notwithstanding, it also exhibits poor solubility and bioavailability that may compromise its clinical application to a great extent. Therefore, the manipulation and encapsulation of curcumin into a nanocarrier formulation can overcome these major drawbacks and potentially may lead to a far superior therapeutic efficacy. Among different types of nanocarriers, biological and biopolymer carriers have attracted a significant attention due to their pleiotropic features. Thus, in the present review, the potential protective and therapeutic applications of curcumin, as well as different types of bio-nanocarriers, which can be used to deliver curcumin effectively to the different target sites will be discussed.

Multifunctional Polymeric Nanoplatforms for Brain Diseases Diagnosis, Therapy and Theranostics

The blood-brain barrier (BBB) acts as a barrier to prevent the central nervous system (CNS) from damage by substances that originate from the blood circulation. The BBB limits drug penetration into the brain and is one of the major clinical obstacles to the treatment of CNS diseases. Nanotechnology-based delivery systems have been tested for overcoming this barrier and releasing related drugs into the brain matrix. In this review, nanoparticles (NPs) from simple to developed delivery systems are discussed for the delivery of a drug to the brain. This review particularly focuses on polymeric nanomaterials that have been used for CNS treatment. Polymeric NPs such as polylactide (PLA), poly (D, L-lactide-co-glycolide) (PLGA), poly (ε-caprolactone) (PCL), poly (alkyl cyanoacrylate) (PACA), human serum albumin (HSA), gelatin, and chitosan are discussed in detail.

Chitosan-based advanced materials for docetaxel and paclitaxel delivery: Recent advances and future directions in cancer theranostics

Paclitaxel (PTX) and docetaxel (DTX) are key members of taxanes with high anti-tumor activity against various cancer cells. These chemotherapeutic agents suffer from a number of drawbacks and it seems that low solubility in water is the most important one. Although much effort has been made in improving the bioavailability of PTX and DTX, the low bioavailability and minimal accumulation at tumor sites are still the challenges faced in PTX and DTX therapy. As a consequence, bio-based nanoparticles (NPs) have attracted much attention due to unique properties. Among them, chitosan (CS) is of interest due to its great biocompatibility. CS is a positively charged polysaccharide with the capability of interaction with negatively charged biomolecules. Besides, it can be processed into the sheet, micro/nano-particles, scaffold, and is dissolvable in mildly acidic pH similar to the pH of the tumor microenvironment. Keeping in mind the different applications of CS in the preparation of nanocarriers for delivery of PTX and DTX, in the present review, we demonstrate that how CS functionalized-nanocarriers and CS modification can be beneficial in enhancing the bioavailability of PTX and DTX, targeted delivery at tumor site, image-guided delivery and co-delivery with other anti-tumor drugs or genes.