Identification of novel STAT3 inhibitors bearing 2-acetyl-7-phenylamino benzofuran scaffold for antitumour study

Design, synthesis and biological evaluation of novel naphthoquinothiazole derivatives as potent antitumor agents through inhibiting STAT3

The signal transducer and activator of transcription 3 (STAT3) has been established as a crucial drug target in the development of antitumor agents. In this study, a series of 21 derivatives of the STAT3 inhibitor napabucasin were designed and synthesized. Through preliminary screening against tumor cell lines, SZ6 emerged as the most potent compound with half maximal inhibitory concentration (IC50) values of 46.3 nM, 66.4 nM, and 53.8 nM against HCT116, HepG2, and Hela cells respectively. Furthermore, SZ6 effectively suppressed tumor invasion and migration in HCT116 cell assays by inducing S-phase arrest and apoptosis through inhibition of Protein Kinase B (PKB/AKT) activity and induction of reactive oxygen species (ROS). The mechanism underlying SZ6's action involves inhibition of STAT3 phosphorylation, which was confirmed by western blotting analysis. Additionally, surface plasmon resonance (SPR) and cellular thermal shift assay (CETSA) demonstrated direct binding between SZ6 and STAT3. Notably, in vivo studies revealed that SZ6 significantly inhibited tumor growth without any observed organ toxicity. Collectively, these findings identify SZ6 as a promising STAT3 inhibitor for colorectal cancer treatment.

BM7, a derivative of benzofuran, effectively fights cancer by promoting cancer cell apoptosis and impacting IL-6 levels

The BM7 compound, a bromo derivative of methyl 6-acetyl-5-hydroxy-2-methyl-1-benzofuran-3-carboxylate, was previously identified as cytotoxic to human leukaemia cells (K562 and HL60) and human cervical cancer (HeLa), while showing no toxicity to non-cancerous primary endothelial cells (HUVEC). In this study, we present the first demonstration of BM7's anticancer efficacy in vivo using a mouse chronic myeloid leukaemia xenograft model. Administered intraperitoneally in a mixture of 10% Solutol HS 15/10% ethanol, BM7 exhibited no visible toxicity and significantly reduced tumor weight, comparable to standard drugs imatinib and hydroxyurea. Further supporting its anticancer potential, a multi-model in vitro study involving seven human cancer cell lines revealed the most promising responses in colon cancer (SW480, SW620, HCT116), liver cancer (HEPG2), and breast adenocarcinoma (MDA-MB-231) cells. BM7 demonstrated multifaceted anticancer mechanisms, inducing apoptosis while elevating reactive oxygen species (ROS) levels and suppressing interleukin-6 (IL-6) release in these cell lines. These findings position BM7 as a candidate of significant interest for cancer therapy. Its ability to not only induce apoptosis but also modulate cellular processes such as ROS levels and immune responses, specifically IL-6 suppression, makes BM7 a versatile and promising agent for further exploration in the realm of cancer treatment.

Anticancer therapeutic potential of benzofuran scaffolds

Benzofuran moiety is the main component of many biologically active natural and synthetic heterocycles. These heterocycles have unique therapeutic potentials and are involved in various clinical drugs. The reported results confirmed the extraordinary inhibitory potency of such benzofurans against a panel of human cancer cell lines compared with a wide array of reference anticancer drugs. Several publications about the anticancer potencies of benzofuran-based heterocycles were encountered. The recent developments of anticancer activities of both natural and synthetic benzofuran scaffolds during 2019-2022 are thoroughly covered. Many of the described benzofurans are promising candidates for development as anticancer agents based on their outstanding inhibitory potency against a panel of human cancer cells compared with reference anticancer drugs. These findings encourage medicinal chemists to explore new areas to improve human health and reduce suffering.

De Novo Design of Imidazopyridine-Tethered Pyrazolines That Target Phosphorylation of STAT3 in Human Breast Cancer Cells

In breast cancer (BC), STAT3 is hyperactivated. This study explored the design of imidazopyridine-tethered pyrazolines as a de novo drug strategy for inhibiting STAT3 phosphorylation in human BC cells. This involved the synthesis and characterization of two series of compounds namely, 1-(3-(2,6-dimethylimidazo [1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-(4-(substituted)piperazin-1-yl)ethanone and N-substituted-3-(2,6-dimethylimidazo[1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazoline-1-carbothioamides. Compound 3f with 2,3-dichlorophenyl substitution was recognized among the tested series as a lead structure that inhibited the viability of MCF-7 cells with an IC₅₀ value of 9.2 μM. A dose- and time-dependent inhibition of STAT3 phosphorylation at Tyr705 and Ser727 was observed in MCF-7 and T47D cells when compound 3f was added in vitro. Calculations using density functional theory showed that the title compounds HOMOs and LUMOs are situated on imidazopyridine-pyrazoline and nitrophenyl rings, respectively. Hence, compound 3f effectively inhibited STAT3 phosphorylation in MCF-7 and T47D cells, indicating that these structures may be an alternative synthon to target STAT3 signaling in BC.

Structure-Activity Relationship of Benzofuran Derivatives with Potential Anticancer Activity

Simple Summary

Cancer is the leading cause of death worldwide and responsible for killing approximately 10 million people per year. Fused heterocyclic ring systems such as benzofuran have emerged as important scaffolds with many biological properties. Furthermore, derivatives of benzofurans demonstrate a wide range of biological and pharmacological activities, including anticancer properties. The main aim of this review is to highlight and discuss the contribution of benzofuran derivatives as anticancer agents by considering and discussing the chemical structure of 20 different compounds. Evaluating the chemical structure of these compounds will guide future medicinal chemists in designing new drugs for cancer therapy that might give excellent results in in vivo/in vitro applications.

Abstract

Benzofuran is a heterocyclic compound found naturally in plants and it can also be obtained through synthetic reactions. Multiple physicochemical characteristics and versatile features distinguish benzofuran, and its chemical structure is composed of fused benzene and furan rings. Benzofuran derivatives are essential compounds that hold vital biological activities to design novel therapies with enhanced efficacy compared to conventional treatments. Therefore, medicinal chemists used its core to synthesize new derivatives that can be applied to a variety of disorders. Benzofuran exhibited potential effectiveness in chronic diseases such as hypertension, neurodegenerative and oxidative conditions, and dyslipidemia. In acute infections, benzofuran revealed anti-infective properties against microorganisms like viruses, bacteria, and parasites. In recent years, the complex nature and the number of acquired or resistant cancer cases have been largely increasing. Benzofuran derivatives revealed potential anticancer activity with lower incidence or severity of adverse events normally encountered during chemotherapeutic treatments. This review discusses the structure–activity relationship (SAR) of several benzofuran derivatives in order to elucidate the possible substitution alternatives and structural requirements for a highly potent and selective anticancer activity.

Protein degradation technology: a strategic paradigm shift in drug discovery

Targeting pathogenic proteins with small-molecule inhibitors (SMIs) has become a widely used strategy for treating malignant tumors. However, most intracellular proteins have been proven to be undruggable due to a lack of active sites, leading to a significant challenge in the design and development of SMIs. In recent years, the proteolysis-targeting chimeric technology and related emerging degradation technologies have provided additional approaches for targeting these undruggable proteins. These degradation technologies show a tendency of superiority over SMIs, including the rapid and continuous target consumption as well as the stronger pharmacological effects, being a hot topic in current research. This review mainly focuses on summarizing the development of protein degradation technologies in recent years. Their advantages, potential applications, and limitations are also discussed. We hope this review would shed light on the design, discovery, and clinical application of drugs associated with these degradation technologies.

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.