NO-releasing STAT3 inhibitors suppress BRAF-mutant melanoma growth

Advancements in Synthetic Strategies and Biological Effects of Ciprofloxacin Derivatives: A Review

Ciprofloxacin is a widely used antibiotic in the fluoroquinolone class. It is widely acknowledged by various researchers worldwide, and it has been documented to have a broad range of other pharmacological activities, such as anticancer, antiviral, antimalarial activities, etc. Researchers have been exploring the synthesis of ciprofloxacin derivatives with enhanced biological activities or tailored capability to target specific pathogens. The various biological activities of some of the most potent and promising ciprofloxacin derivatives, as well as the synthetic strategies used to develop them, are thoroughly reviewed in this paper. Modification of ciprofloxacin via 4-oxo-3-carboxylic acid resulted in derivatives with reduced efficacy against bacterial strains. Hybrid molecules containing ciprofloxacin scaffolds displayed promising biological effects. The current review paper provides reported findings on the development of novel ciprofloxacin-based molecules with enhanced potency and intended therapeutic activities which will be of great interest to medicinal chemists.

Targeting JAK2/STAT3 for the treatment of cancer: A review on recent advancements in molecular development using structural analysis and SAR investigations

Cancer is indeed considered a hazardous and potentially life-threatening disorder. The JAK/STAT pathway is an important intracellular signaling cascade essential for many physiological functions, such as immune response, cell proliferation, and differentiation. Dysregulation of this pathway aids in the progression and development of cancer. The downstream JAK2/STAT3 signaling cascades are legitimate targets against which newer anticancer drugs can be developed to prevent and treat cancer. Understanding the mechanisms behind JAK2/STAT3 participation in cancer has paved the way for developing innovative targeted medicines with the potential to improve cancer treatment outcomes. This article provides information on the current scenario and recent advancements in the design and development of anticancer drugs targeting JAK2/STAT3, including structural analysis and SAR investigations of synthesized molecules. Numerous preclinical and clinical trials are ongoing on these inhibitors, which are highlighted to gain more insight into the broader development prospects of inhibitors of JAK2/STAT3.

A glycyrrhetinic acid-iridium(III) conjugate as a theranostic NIR probe for hepatocellular carcinoma with mitochondrial-targeting ability

Hepatocellular carcinoma (HCC) is a major contributor to global mortality rates, but current treatment options have limitations. Advanced theranostics are needed to effectively integrate diagnosis and therapeutic of HCC. Glycyrrhetinic acid (GA) has abundant binding sites with glycyrrhetinic acid receptors (GA-Rs) on the surface of HCC cells and has also been reported to possess ligands with mitochondrial-targeting capability but with limited efficacy. Herein, we report a near-infrared (NIR) luminescent theranostic complex 1 through conjugating an iridium(III) complex to GA, which exhibits the desired photophysical properties and promotes mitochondrial-targeting capability. Complex 1 was selectively taken up by HepG2 liver cancer cells and was imaged within mitochondria with NIR emission. Complex 1 targeted mitochondria and opened mitochondrial permeability transition pores (MPTPs), resulting in ROS accumulation, mitochondrial damage, disruption of Bax/Bcl-2 equilibrium, and tumor cell apoptosis, resulting in significantly improved anticancer activity compared to GA. This work offers a methodology for developing multifunctional theranostic probes with amplified specificity and efficacy.

New 1,2,3-triazole/1,2,4-triazole hybrids linked to oxime moiety as nitric oxide donor selective COX-2, aromatase, B-RAFV600E and EGFR inhibitors celecoxib analogs: design, synthesis, anti-inflammatory/anti-proliferative activities, apoptosis and molecular modeling study

A new series of bis-triazole 19a-l was synthesised for the purpose of being hybrid molecules with both anti-inflammatory and anti-cancer activities and assessed for cell cycle arrest, NO release. Compounds 19c, 19f, 19h, 19 l exhibited COX-2 selectivity indexes in the range of 18.48 to 49.38 compared to celecoxib S.I. = 21.10), inhibit MCF-7 with IC50 = 9-16 μM compared to tamoxifen (IC50 = 27.9 μM). and showed good inhibitory activity against HEP-3B with IC50 = 4.5-14 μM compared to sorafenib (IC50 = 3.5 μM) (HEP-3B). Moreover, derivatives 19e, 19j, 19k, 19 l inhibit HCT-116 with IC50 = 5.3-13.7 μM compared to 5-FU with IC50 = 4.8 μM (HCT-116). Compounds 19c, 19f, 19h, 19 l showed excellent inhibitory activity against A549 with IC50 = 3-4.5 μM compared to 5-FU with IC50 = 6 μM (A549). Compounds 19c, 19f, 19h, 19 l inhibit aromatase (IC50 of 22.40, 23.20, 22.70, 30.30 μM), EGFR (IC50 of 0.112, 0.205, 0.169 and 0.066 μM) and B-RAFV600E (IC50 of 0.09, 0.06, 0.07 and 0.05 μM).

Hyperforin Elicits Cytostatic/Cytotoxic Activity in Human Melanoma Cell Lines, Inhibiting Pro-Survival NF-κB, STAT3, AP1 Transcription Factors and the Expression of Functional Proteins Involved in Mitochondrial and Cytosolic Metabolism

Hyperforin (HPF), the main component responsible for the antidepressant action of Hypericum perforatum, displays additional beneficial properties including anti-inflammatory, antimicrobic, and antitumor activities. Among its antitumor effects, HPF activity on melanoma is poorly documented. Melanoma, especially BRAF-mutated melanoma, is still a high-mortality tumor type and the currently available therapies do not provide solutions. We investigated HPF's antimelanoma effectiveness in A375, FO1 and SK-Mel-28 human BRAF-mutated cell lines. Cell viability assays documented that all melanoma cells were affected by low HPF concentrations (EC50% 2-4 µM) in a time-dependent manner. A Br-deoxy-uridine incorporation assay attested a significant reduction of cell proliferation accompanied by decreased expression of cyclin D1 and A2, CDK4 and of the Rb protein phosphorylation, as assessed by immunoblots. In addition, the expression of P21/waf1 and the activated form of P53 were increased in A375 and SK-Mel-28 cells. Furthermore, HPF exerts cytotoxic effects. Apoptosis is induced 24 h after HPF administration, documented by an increase of cleaved-PARP1 and a decrease of both Bcl2 and Bcl-xL expression levels. Autophagy is induced, attested by an augmented LC3B expression and augmentation of the activated form of AMPK. Moreover, HPF lowers GPX4 enzyme expression, suggesting ferroptosis induction. HPF has been reported to activate the TRPC6 Ca⁺⁺ channel and/or Ca⁺⁺ and Zn⁺⁺ release from mitochondria stores, increasing cytosolic Ca⁺⁺ and Zn⁺⁺ concentrations. Our data highlighted that HPF affects many cell-signaling pathways, including signaling induced by Ca⁺⁺, such as FRA1, pcJun and pCREB, the expression or activity of which are increased shortly after treatment. However, the blockage of the TRPC6 Ca⁺⁺ channel or the use of Ca⁺⁺ and Zn⁺⁺ chelators do not hinder HPF cytostatic/cytotoxic activity, suggesting that damages induced in melanoma cells may pass through other pathways. Remarkably, 24 h after HPF treatment, the expression of activated forms of the transcription factors NF-κB P65 subunit and STAT3 are significantly lowered. Several cytosolic (PGM2, LDHA and pPKM2) and mitochondrial (UQCRC1, COX4 and ATP5B) enzymes are downregulated by HPF treatment, suggesting a generalized reduction of vital functions in melanoma cells. In line with these results is the recognized ability of HPF to affect mitochondrial membrane potential by acting as a protonophore. Finally, HPF can hinder both melanoma cell migration and colony formation in soft agar. In conclusion, we provide evidence of the pleiotropic antitumor effects induced by HPF in melanoma cells.

Design, synthesis, and biological investigation of quinoline/ciprofloxacin hybrids as antimicrobial and anti-proliferative agents

Ciprofloxacin-Piperazine C-7 linked quinoline derivatives 6a–c and 8a–c were synthesized and investigated for their antibacterial, antifungal, and anti-proliferative activities. Ciprofloxacin-quinoline-4-yl-1,3,4 oxadiazoles 6a and 6b showed promising anticancer activity against SR- leukemia and UO-31 renal cancer cell lines. The hybrids 8a–c and compound 6b exhibited noticeable antifungal activities against C.Albicans; 8a experienced the most potent antifungal activity compared to Itraconazole with MICs of 21.88 µg/mL and 11.22 µg/mL; respectively. Most of derivatives displayed better antibacterial activity than the parent ciprofloxacin against all the tested strains. Compound 6b was the most potent against the highly resistant Gram-negative K.pneumoniae with MIC 16.96 of µg/mL relative to the parent ciprofloxacin (MIC = 29.51 µg/mL). Docking studies of the tested hydrides in the active site of Topo IV enzyme of K.pneumoniae (5EIX) and S.aureus gyrase (2XCT) indicate that they had stronger binding affinity in both enzymes than ciprofloxacin but have different binding interactions. The hybrid 6b could be considered a promising lead compound for finding new dual antibacterial/anticancer agents. Moreover, Compound 8a could be a lead for discovering new dual antibacterial/antifungal agents.

Graphical abstract

Targeting oncogenic transcription factors in skin malignancies: An update on cancer stemness and therapeutic outcomes

The skin is the largest organ of the human body and prone to various diseases, including cancer; thus, provides the first line of defense against exogenous biological and non-biological agents. Skin cancer, a complex and heterogenic process, with steep incidence rate often metastasizes due to poor understanding of the underlying mechanisms of pathogenesis and clinical challenges. Indeed, accumulating evidence indicates that deregulation of transcription factors (TFs) due to genetic, epigenetic and signaling distortions plays essential role in the development of cutaneous malignancies and therapeutic challenges including cancer stemness features and reprogramming. This review highlights the recent developments exploring underlying mechanisms how deregulated TFs (e.g., NF-κB, AP-1, STAT etc.,) orchestrates cutaneous onco-pathogenesis, reprogramming, stemness and poor clinical outcomes. Along this line, bioactive drugs, and their derivatives from natural and or synthetic origin has gained attention due to their multitargeting potential, potentially safer and effective therapeutic outcome for human malignancies. We also discussed therapeutic importance of targeting aberrantly expressed TFs in skin cancers with bioactive natural products and or synthetic agents.

Exploration of Isoxazole-Carboxylic Acid Methyl Ester Based 2-Substituted Quinoline Derivatives as Promising Antitubercular Agents

In pursuit of potent anti-TB agents active against drug resistant tuberculosis (DR-TB), herein we report synthesis and bio-evaluation of a new series of isoxazole-carboxylic acid methyl ester based 2-substituted quinoline derivatives. Preliminary evaluation indicated selectivity towards Mtb H37Rv, with no inhibition of non-tubercular mycobacterial (NTM) & bacterial pathogen panel. Out of 36 synthesized compounds, majority exhibited substantial inhibition of Mtb H37Rv (MIC 0.5-8 μg/mL). Cell viability test against Vero cells revealed no significant cytotoxicity. Further, screening against drug resistant strains (DR-Mtb) found hit compound displaying promising potency (MIC 1-4 μg/mL). Structure optimization of the hit led to the identification of lead compound demonstrating potent inhibition of both drug-susceptible Mtb (MIC 0.12 μg/mL) and drug-resistant Mtb (MIC 0.25-0.5 μg/mL) along with a high selectivity index (SI) >80. Taken together, with appreciable selectivity and potent activity, these chemotypes show prospect to be turned into a potential anti-TB candidate.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

Disruption of Redox Homeostasis by Alterations in Nitric Oxide Synthase Activity and Tetrahydrobiopterin along with Melanoma Progression

Cutaneous melanoma emerges from the malignant transformation of melanocytes and is the most aggressive type of skin cancer. The progression can occur in different stages: radial growth phase (RGP), vertical growth phase (VGP), and metastasis. Reactive oxygen species contribute to all phases of melanomagenesis through the modulation of oncogenic signaling pathways. Tetrahydrobiopterin (BH4) is an important cofactor for NOS coupling, and an uncoupled enzyme is a source of superoxide anion (O2•-) rather than nitric oxide (NO), altering the redox homeostasis and contributing to melanoma progression. In the present work, we showed that the BH4 amount varies between different cell lines corresponding to distinct stages of melanoma progression; however, they all presented higher O2•- levels and lower NO levels compared to melanocytes. Our results showed increased NOS expression in melanoma cells, contributing to NOS uncoupling. BH4 supplementation of RGP cells, and the DAHP treatment of metastatic melanoma cells reduced cell growth. Finally, Western blot analysis indicated that both treatments act on the PI3K/AKT and MAPK pathways of these melanoma cells in different ways. Disruption of cellular redox homeostasis by the altered BH4 concentration can be explored as a therapeutic strategy according to the stage of melanoma.

Salviolone from Salvia miltiorrhiza Roots Impairs Cell Cycle Progression, Colony Formation, and Metalloproteinase-2 Activity in A375 Melanoma Cells: Involvement of P21(Cip1/Waf1) Expression and STAT3 Phosphorylation

Melanoma is a highly malignant solid tumor characterized by an elevated growth and propagation rate. Since, often, melanoma treatment cannot prevent recurrences and the appearance of metastasis, new anti-melanoma agents need to be discovered. Salvia miltiorrhiza roots are a source of diterpenoid derivatives, natural compounds with several biological activities, including antiproliferative and anticancer effects. Seven diterpenoid derivatives were purified from S. miltiorrhiza roots and identified by NMR and MS analysis. Tanshinone IIA and cryptotanshinone were detected as the main components of S. miltiorrhiza root ethanol extract. Although their antitumor activity is already known, they have been confirmed to induce a reduction in A375 and MeWo melanoma cell growth. Likewise, salviolone has been shown to impair the viability of melanoma cells without affecting the growth of normal melanocytes. The underlying anticancer activity of salviolone has been investigated and compared to that of cryptotanshinone in A375 cells, showing an increased P21 protein expression in a P53-dependent manner. In that way, salviolone, even more than cryptotanshinone, displays a multitarget effect on cell-cycle-related proteins. Besides, it modulates the phosphorylation level of the signal transducer and activator of transcription (STAT)3. Unexpectedly, salviolone and cryptotanshinone induce sustained activation of the extracellular signal-regulated kinases (ERK)1/2 and the protein kinase B (Akt). However, the blockage of ERK1/2 or Akt activities suggests that kinase activation does not hinder their ability to inhibit A375 cell growth. Finally, salviolone and cryptotanshinone inhibit to a comparable extent some crucial malignancy features of A375 melanoma cells, such as colony formation in soft agar and metalloproteinase-2 activity. In conclusion, it has been shown for the first time that salviolone, harboring a different molecular structure than tanshinone IIA and cryptotanshinone, exhibits a pleiotropic effect against melanoma by hampering cell cycle progression, STAT3 signaling, and malignant phenotype of A375 melanoma cells.

Recent contributions of quinolines to antimalarial and anticancer drug discovery research

Quinoline, a privileged scaffold in medicinal chemistry, has always been associated with a multitude of biological activities. Especially in antimalarial and anticancer research, quinoline played (and still plays) a central role, giving rise to the development of an array of quinoline-containing pharmaceuticals in these therapeutic areas. However, both diseases still affect millions of people every year, pointing to the necessity of new therapies. Quinolines have a long-standing history as antimalarial agents, but established quinoline-containing antimalarial drugs are now facing widespread resistance of the Plasmodium parasite. Nevertheless, as evidenced by a massive number of recent literature contributions, they are still of great value for future developments in this field. On the other hand, the number of currently approved anticancer drugs containing a quinoline scaffold are limited, but a strong increase and interest in quinoline compounds as potential anticancer agents can be seen in the last few years. In this review, a literature overview of recent contributions made by quinoline-containing compounds as potent antimalarial or anticancer agents is provided, covering publications between 2018 and 2020.

Development of 2'-aminospiro [pyrano[3,2-c]quinoline]-3'-carbonitrile derivatives as non-ATP competitive Src kinase inhibitors that suppress breast cancer cell migration and proliferation

Src kinase activity controls diverse cellular functions, including cell growth, migration, adhesion, and survival. It is de-regulated in several cancers, including breast cancer, where it is highly expressed and phosphorylated. Thus, targeting Src by a small molecule is a feasible strategy for managing different breast cancer types. Several Src kinase inhibitors are available, including the FDA-approved drug (dasatinib). However, they are primarily ATP-competitive inhibitors that have been reported to lack specificity towards Src. We have a long-time interest in discovering protein kinase inhibitors that are non-competitive for ATP. In this project, three groups of 2'-aminospiro[pyrano[3,2-c]quinoline]-3'-carbonitrile derivatives were designed and synthesized, hypothesizing that small molecules with a spiro scaffold appended to a pyrano[3,2-c]quinoline analog could act as non-ATP competitive Src kinase inhibitors. 3b, 3c, and 3d inhibited Src kinase activity with IC50s of 4.9, 5.9, and 0.9 μM, respectively. At the same time, they did not impact the MDM2/p53 interaction in HEK293 cells, which has been reported to be affected by some spirocyclic compounds. 25 µM of 3b, 3c, or 3d did not inhibit the kinase activity of ERK2, JNK1, or p38-alpha in an in-vitro kinase assay. Steady-state kinetic studies for the effect of 3d on the ability of recombinant Src to phosphorylate its substrate (Srctide) revealed a non-ATP competitive inhibition mechanism. 1.6 µM of 3d was enough to diminish Src, Fak, and paxillin phosphorylation in the breast cancer cell lines MDA-MB-231 and MCF7. In the NCI screening, 3d induced broad tumor cytotoxicity for the NCI-60 cell lines, including all the breast cancer cell lines. The potency of 3b, 3c, and 3d to inhibit migration, proliferation, and colony formation of MDA-MB-231 and proliferation of MCF7 cells correlates with their potency to suppress Src kinase activity in the same cell line. Noticeably, the cell growth suppression and apoptosis induction in the tested cell lines can be attributed to the ability of the new derivatives to suppress the ERK and Akt survival pathways downstream of Src.

Synthesis and biological evaluation of NO-donor containing photosensitizers to induce ferroptosis of cancer cells

Photodynamic therapy (PDT) is a non-invasive treatment method for tumors by exciting photosensitizers (PS) upon light irradiation to generate cytotoxic reactive oxygen species (ROS). However, the low oxygen concentration near the tumor tissue limits the therapeutic effect of PDT. Herein, we synthesized six chlorin e6 derivatives containing NO-donors to enhance their antitumor activity by synergistic effect of ROS and NO. The results revealed that the new NO-donor containing photosensitizers (PS-NO) exhibited more potent photodynamic activity than chlorin e6, and the introduction of NO donor moieties to chlorin e6 increased the level of NO and ROS in cells. The addition of Ferrostatin-1, a ferroptosis inhibitor, markedly reduced the photodynamic activity of PS-NO as well as the level of NO and ROS in cells. Mechanism studies further showed that PS-NO could reduce intracellular GSH level, inhibit GPX4 activity and promote malondialdehyde (MDA) accumulation upon light irradiation, which suggested the ferroptosis mechanism underlying the PDT effect of PS-NO.

Nitric Oxide Induction in Peritoneal Macrophages by a 1,2,3-Triazole Derivative Improves Its Efficacy upon Leishmania amazonensis In Vitro Infection

1,2,3-Triazole is one of the most flexible chemical scaffolds broadly used in various fields. Here, we report the antileishmanial activity of 1,2,3-triazole derivatives, the ultrastructural alterations induced by their treatment, and the nitric oxide (NO) modulation effect on their efficacy against Leishmania amazonensis in vitro infection. After the screening of eleven compounds, compound 4 exhibited better results against L. amazonensis promastigotes (IC₅₀ = 15.52 ± 3.782 μM) and intracellular amastigotes (IC₅₀ = 4.10 ± 1.136 μM), 50% cytotoxicity concentration at 84.01 ± 3.064 μM against BALB/c peritoneal macrophages, and 20.49-fold selectivity for the parasite over the cells. Compound 4 induced ultrastructural mitochondrial alterations and lipid inclusions in L. amazonensis promastigotes, upregulated tumor necrosis factor α, interleukin (IL)-1β, IL-6, IL-12, and IL-10 messenger RNA expressions, and enhanced the NO production, verified by nitrite (p = 0.0095) and inducible nitric oxide synthase expression (p = 0.0049) quantification, which played an important role in its activity against intramacrophagic L. amazonensis. In silico prediction in association with antileishmanial activity results showed compound 4 as a hit compound with promising potential for further studies of new leishmaniasis treatment options.

Direct C-C Bond Cleavage of 1,3-Dicarbonyl Compounds as a Single-Carbon Synthon: Synthesis of 2-Aryl-4-quinolinecarboxylates

A novel [2 + 1 + 3] cyclization reaction for the synthesis of 2-aryl-4-quinolinecarboxylates from aryl methyl ketones, arylamines, and 1,3-dicarbonyl compounds has been established. This metal-free process achieved the C-C bond cleavage of 1,3-dicarbonyl compounds directly as a single-carbon synthon. The reaction is highly efficient and has good substrate compatibility while operating under mild conditions. This method has good practicability and successfully realized the synthesis of bioactive molecules.

Recent Update on Development of Small-Molecule STAT3 Inhibitors for Cancer Therapy: From Phosphorylation Inhibition to Protein Degradation

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that regulates various biological processes, including proliferation, metastasis, angiogenesis, immune response, and chemoresistance. In normal cells, STAT3 is tightly regulated to maintain a transiently active state, while persistent STAT3 activation occurs frequently in cancers, associating with a poor prognosis and tumor progression. Targeting the STAT3 protein is a potentially promising therapeutic strategy for tumors. Although none of the STAT3 inhibitors has been marketed yet, a few of them have succeeded in entering clinical trials. This Review aims to systematically summarize the progress of the last 5 years in the discovery of directive STAT3 small-molecule inhibitors and degraders, focusing primarily on their structural features, design strategies, and bioactivities. We hope this Review will shed light on future drug design and inhibitor optimization to accelerate the discovery process of STAT3 inhibitors or degraders.

Neuroendocrine Factors in Melanoma Pathogenesis

Simple Summary

Melanoma is a very aggressive and fatal malignant tumor. While curable if diagnosed in its early stages, advanced melanoma, despite the complex therapeutic approaches, is associated with one of the highest mortality rates. Hence, more and more studies have focused on mechanisms that may contribute to melanoma development and progression. Various studies suggest a role played by neuroendocrine factors which can act directly on tumor cells, modulating their proliferation and metastasis capability, or indirectly through immune or inflammatory processes that impact disease progression. However, there are still multiple areas to explore and numerous unknown features to uncover. A detailed exploration of the mechanisms by which neuroendocrine factors can influence the clinical course of the disease could open up new areas of biomedical research and may lead to the development of new therapeutic approaches in melanoma.

Abstract

Melanoma is one of the most aggressive skin cancers with a sharp rise in incidence in the last decades, especially in young people. Recognized as a significant public health issue, melanoma is studied with increasing interest as new discoveries in molecular signaling and receptor modulation unlock innovative treatment options. Stress exposure is recognized as an important component in the immune-inflammatory interplay that can alter the progression of melanoma by regulating the release of neuroendocrine factors. Various neurotransmitters, such as catecholamines, glutamate, serotonin, or cannabinoids have also been assessed in experimental studies for their involvement in the biology of melanoma. Alpha-MSH and other neurohormones, as well as neuropeptides including substance P, CGRP, enkephalin, beta-endorphin, and even cellular and molecular agents (mast cells and nitric oxide, respectively), have all been implicated as potential factors in the development, growth, invasion, and dissemination of melanoma in a variety of in vitro and in vivo studies. In this review, we provide an overview of current evidence regarding the intricate effects of neuroendocrine factors in melanoma, including data reported in recent clinical trials, exploring the mechanisms involved, signaling pathways, and the recorded range of effects.

Design, synthesis, and antibacterial evaluation of new quinoline-1,3,4-oxadiazole and quinoline-1,2,4-triazole hybrids as potential inhibitors of DNA gyrase and topoisomerase IV

DNA gyrase and topoisomerase IV (topo IV) inhibitors are among the most interesting antibacterial drug classes without antibacterial pipeline representative. Twenty-four new quinoline-1,3,4-oxadiazole and quinoline-1,2,4-triazole hybrids were developed and tested against DNA gyrase and topoisomerase IV from Escherichia coli and Staphylococcus aureus. The most potent compounds 4c, 4e, 4f, and 5e displayed an IC₅₀ of 34, 26, 32, and 90 nM against E. coli DNA gyrase, respectively (novobiocin, IC₅₀ = 170 nM). The activities of 4c, 4e, 4f, and 5e on DNA gyrase from S. aureus were weaker than those on E. coli gyrase. Compound 4e showed IC₅₀ values (0.47 µM and 0.92 µM) against E. coli topo IV and S. aureus topo IV, respectively in comparison to novobiocin (IC₅₀ = 11, 27 µM, respectively). Antibacterial activity against Gram-positive and Gram-negative bacterial strains has been studied. Some compounds have demonstrated superior antibacterial activity to ciprofloxacin against some of the bacterial strain studied. The most active compounds in this study showed no cytotoxic effect with cell viability>86%. Finally, a molecular docking analysis was performed to investigate the binding mode and interactions of the most active compounds to the active site of DNA gyrase and topoisomerase IV (topo IV) enzymes.

Design and synthesis of novel quinoline/chalcone/1,2,4-triazole hybrids as potent antiproliferative agent targeting EGFR and BRAFV600E kinases

New quinoline / chalcone hybrids containing 1,2,4-triazole moiety have been designed, synthesized and their structures elucidated and confirmed by various spectroscopic techniques. The designed compounds showed moderate to good activity on different NCI 60 cell lines in a single-dose assay with a growth inhibition rate ranging from 50% to 94%. Compounds 7b, 7d, 9b, and 9d were the most active compounds in most cancer cell lines with a growth inhibition percent between 77% and 94%. Newly synthesized hybrids were evaluated for their anti-proliferative activity against a panel of four human cancer cell lines. Compounds 7a, 7b, 9a, 9b, and 9d showed promising antiproliferative activities. These compounds were further tested for their inhibitory potency against EGFR and BRAF^V600E kinases with erlotinib as a reference drug. The molecular docking study of compounds 7a, 7b, 9a, 9b, and 9d revealed nice fitting into the active site of EGFR and BRAF^V600E kinases. Compounds 7b, 9b, and 9d displayed the highest binding affinities and similar binding pattern to those of erlotinib.

Mechanisms of Acquired BRAF Inhibitor Resistance in Melanoma: A Systematic Review

This systematic review investigated the literature on acquired v-raf murine sarcoma viral oncogene homolog B1 (BRAF) inhibitor resistance in patients with melanoma. We searched MEDLINE for articles on BRAF inhibitor resistance in patients with melanoma published since January 2010 in the following areas: (1) genetic basis of resistance; (2) epigenetic and transcriptomic mechanisms; (3) influence of the immune system on resistance development; and (4) combination therapy to overcome resistance. Common resistance mutations in melanoma are BRAF splice variants, BRAF amplification, neuroblastoma RAS viral oncogene homolog (NRAS) mutations and mitogen-activated protein kinase kinase 1/2 (MEK1/2) mutations. Genetic and epigenetic changes reactivate previously blocked mitogen-activated protein kinase (MAPK) pathways, activate alternative signaling pathways, and cause epithelial-to-mesenchymal transition. Once BRAF inhibitor resistance develops, the tumor microenvironment reverts to a low immunogenic state secondary to the induction of programmed cell death ligand-1. Combining a BRAF inhibitor with a MEK inhibitor delays resistance development and increases duration of response. Multiple other combinations based on known mechanisms of resistance are being investigated. BRAF inhibitor-resistant cells develop a range of 'escape routes', so multiple different treatment targets will probably be required to overcome resistance. In the future, it may be possible to personalize combination therapy towards the specific resistance pathway in individual patients.

STAT3 transcription factor as target for anti-cancer therapy

STATs constitute a large family of transcription activators and transducers of signals that have an important role in many cell functions as regulation of proliferation and differentiation of the cell also regulation of apoptosis and angiogenesis. STAT3 as a member of that family, recently was discovered to have a vital role in progression of different types of cancers. The activation of STAT3 was observed to regulate multiple gene functions during cancer-like cell proliferation, differentiation, apoptosis, metastasis, inflammation, immunity, cell survival, and angiogenesis. The inhibition of STAT3 activation has been an important target for cancer therapy. Inhibitors of STAT3 have been used for a long time for treatment of many types of cancers like leukemia, melanoma, colon, and renal cancer. In this review article, we summarize and discuss different drugs inhibiting the action of STAT3 and used in treatment of different types of cancer.

Unravelling the anticancer potency of 1,2,4-triazole-N-arylamide hybrids through inhibition of STAT3: synthesis and in silico mechanistic studies

The discovery of potent STAT3 inhibitors has gained noteworthy impetus in the last decade. In line with this trend, considering the proven biological importance of 1,2,4-triazoles, herein, we are reporting the design, synthesis, pharmacokinetic profiles, and in vitro anticancer activity of novel C3-linked 1,2,4-triazole-N-arylamide hybrids and their in silico proposed mechanism of action via inhibition of STAT3. The 1,2,4-triazole scaffold was selected as a privilege ring system that is embedded in core structures of a variety of anticancer drugs which are either in clinical use or still under clinical trials. The designed 1,2,4-triazole derivatives were synthesized by linking the triazole-thione moiety through amide hydrophilic linkers with diverse lipophilic fragments. In silico study to predict cytotoxicity of the new hybrids against different kinds of human cancer cell lines as well as the non-tumor cells was conducted. The multidrug-resistant human breast adenocarcinoma cells (MDA-MB-231) was found most susceptible to the cytotoxic effect of synthesized compounds and hence were selected to evaluate the in vitro anticancer activity. Four of the designed derivatives showed promising cytotoxicity effects against selected cancer cells, among which compound 12 showed the highest potency (IC₅₀ = 3.61 µM), followed by 21 which displayed IC₅₀ value of 3.93 µM. Also, compounds 14 and 23 revealed equipotent activity with the reference cytotoxic agent doxorubicin. To reinforce these observations, the obtained data of in vitro cytotoxicity have been validated in terms of ligand-protein interaction and new compounds were analyzed for ADMET properties to evaluate their potential to build up as good drug candidates. This study led us to identify two novel C3-linked 1,2,4-triazole-N-arylamide hybrids of interesting antiproliferative potentials as probable lead inhibitors of STAT3 with promising pharmacokinetic profiles.

Epithelioid glioblastoma with microglia features: potential for novel therapy

Epithelioid glioblastoma (E‐GBM) was recently designated as a subtype of glioblastoma (GBM) by the World Health Organization (2016). E‐GBM is an aggressive and rare variant of GBM that primarily occurs in children and young adults. Although most characterized cases of E‐GBM harbor a mutation of the BRAF gene in which valine (V) is substituted by glutamic acid (E) at amino acid 600 (BRAF‐V600E), in addition to telomerase reverse transcriptase promoter mutations and homozygous CDKN2A/B deletions, the origins and cellular nature of E‐GBM remain uncertain. Here, we present a case of E‐GBM that exhibits antigenic and functional traits suggestive of microglia. Although no epithelial [e.g., CKAE1/3, epithelial membrane antigen (EMA)] or glial (e.g., GFAP, Olig2) markers were detected by immunohistochemical staining, the microglial markers CD68 and Iba1 were readily apparent. Furthermore, isolated E‐GBM‐derived tumor cells expressed microglial/macrophage‐related genes including cytokines, chemokines, MHC class II antigens, lysozyme and the critical functional receptor, CSF‐1R. Isolated E‐GBM‐derived tumor cells were also capable of phagocytosis and cytokine production. Treating E‐GBM‐derived tumor cells with the BRAF‐V600E inhibitor, PLX4032 (vemurafenib), resulted in a dose‐dependent reduction in cell viability that was amplified by addition of the CSF‐1R inhibitor, BLZ945. The present case provides insight into the cellular nature of E‐GBM and introduces several possibilities for effective targeted therapy for these patients.

Columbamine suppresses proliferation and invasion of melanoma cell A375 via HSP90-mediated STAT3 activation

PURPOSE

The goal of this study is to explore the effects of columbamine in melanoma cells and the signaling pathway involved.

METHODS

Human melanoma cell line A375 cells were used in this study. Cell proliferative ability was detected by MTT assay and clone formation assay. Cell migration and invasion were measured by wound healing assay and transwell assay, respectively. Protein expression was examined by Western blotting.

RESULTS

Columbamine reduced cell proliferative ability and the number of clone spots in A375 cells. Western blotting results demonstrated that expression of cleaved caspase 3, an activated cell death protease, was upregulated by 20 and 50 µM of columbamine. Wound healing results showed that the scratch width was wider in cell treated with 20 and 50 µM of columbamine than that in cell treated with 0 and 10 µM of columbamine. Phosphorylation of STAT3 and expression of HSP90 was also repressed by columbamine in a concentration-dependent manner. Overexpression of HSP90 attenuated the inhibition of cell proliferation, migration and invasion induced by columbamine.

CONCLUSION

Columbamine inhibited melanoma cell proliferation, migration, and invasion in A375 cells through inactivation of STAT3, which is mediated by HSP90.

Sensitizing activities of nitric oxide donors for cancer resistance to anticancer therapeutic drugs

Cancer is not a single disease but it constitutes a large variety of different types that are also different from each other phenotypically and molecularly. Although the standard treatments have resulted in clinical responses in a subset of patients, though, many patients relapse and no longer respond to further treatments. Hence, both the innate and adaptive resistance to treatments are the main challenges in today's treatment strategies. Noteworthy, several novel treatment strategies, particularly immunotherapies, used alone or in combination, have been developed and that have significantly improved the therapeutic response of many unresponsive cancer patients. Nevertheless, even with the latest new developments of therapeutics that were effective in a larger subset of patients, there is still an urgent need to treat the remaining unresponsive subset of patients. This requires the development of new targeting agents of superior antitumor activities that will lead to overcoming the unaffected resistance by current treatments. There has been accumulating evidence suggesting nitric oxide donors as such targeting agents and considering their pleiotropic antitumor activities, including both the reversal of chemo and immuno-resistance of various unresponsive resistant cancers. The in vitro and in vivo preclinical findings corroborate the sensitizing antitumor activities of nitric oxide donors. In addition, a few clinical findings with NO donors that have been applied in patients have corroborated their antitumor and sensitizing activities in combination with standard therapies. In this review, the role and underlying mechanisms by which nitric oxide donors sensitize cancer resistant cells to both chemotherapy and immunotherapy are briefly described.

Protein kinase inhibitor-based cancer therapies: Considering the potential of nitric oxide (NO) to improve cancer treatment

The deregulation of a wide variety of protein kinases is associated with cancer cell initiation and tumor progression. Owing to their indispensable function in signaling pathways driving malignant cell features, protein kinases constitute major therapeutic targets in cancer. Over the past two decades, intense efforts in drug development have been dedicated to this field. The development of protein kinase inhibitors (PKIs) have been a real breakthrough in targeted cancer therapy. Despite obvious successes across patients with different types of cancer, the development of PKI resistance still prevails. Combination therapies are part of a comprehensive approach to address the problem of drug resistance. The therapeutic use of nitric oxide (NO) donors to bypass PKI resistance in cancer has never been tested in clinic yet but several arguments suggest that the combination of PKIs and NO donors may exert a potential anticancer effect. The present review summarized the current state of knowledge on common targets to both PKIs and NO. Herein, we attempt to provide the rationale underlying a potential combination of PKIs and NO donors for future directions and design of new combination therapies in cancer.