Targeting the STAT3 pathway with STAT3 degraders

Elucidating the anticancer potential of dendrobine in renal cell carcinoma treatment

Renal cell carcinoma (RCC) is the predominant form of kidney cancer. Despite the significant improvements in survival rates for advanced RCC patients due to targeted therapy and immunotherapy, challenges such as drug resistance and severe adverse reactions continue to hinder effective management. Therefore, there is an urgent need to identify new therapeutic agents for RCC. Natural products, derived from plants, animals, and microorganisms, are increasingly recognized for their potential in treating complex diseases such as cancer. Dendrobine, a natural product extracted from Dendrobium, holds significant anticancer potential. However, its role in anti-RCC therapy remains poorly understood. This study applied network pharmacology to explore the role of Dendrobine in RCC treatment, identifying STAT3 as a key target. Furthermore, a series of in vitro experiments confirmed that Dendrobine inhibits RCC cell growth. CCK-8 assays demonstrated that Dendrobine inhibits RCC cell viability in a concentration-dependent manner, with an IC50 of 142.5 μM for 786-O cells and 146.5 μM for A498 cells. Clonogenic formation assays and EdU staining confirmed that Dendrobine suppresses RCC cell proliferation. Wound healing and invasion assays showed that Dendrobine inhibits RCC cell migration and invasion. Hoechst 33342/PI co-staining demonstrated that Dendrobine induces apoptosis in RCC cells. Mechanistically, Western blot analysis revealed that Dendrobine targets the PI3K/Akt signaling pathway by inhibiting the expression of p-PI3K, p-Akt, and p-Erk. Overall, this study seeks to elucidate the underlying pharmacological mechanisms and provide new insights for potential therapeutic strategies in RCC.

STAT3 Inhibition Prevents Adaptive Resistance and Augments NK Cell Cytotoxicity to KRASG12C Inhibitors in Nonsmall Cell Lung Cancer

KRASG12C inhibitors exhibit conspicuous clinical response in KRASG12C-mutant lung cancer, yet adaptive resistance, the rapid onset of intrinsic resistance, dampens their therapeutic success. Rational combination strategies could tackle this challenging problem. A high-throughput screening of a pharmacological library with 423 compounds revealed that napabucasin, a signal transducer and activator of transcription 3 (STAT3) inhibitor, synergistically potentiated the growth inhibition effect of the KRASG12C inhibitor sotorasib in sensitive and resistant KRASG12C NSCLC cell lines. Functional assays further revealed that the coordinated targeting of KRAS with STAT3 improved the inhibitory effect on tumor growth and augmented the infiltration and activation of natural killer (NK) cells within the tumor microenvironment. Mechanistically, KRASG12C inhibition induced compensatory activation of STAT3, contingent on concomitant suppression of downstream ERK signaling, abrogated by napabucasin. Moreover, we unveiled and verified the binding site of phosphorylated STAT3 at the HLA-B promoter, an inhibitor ligand for NK cells. Our study dissected an unknown mechanism of adaptive resistance to KRASG12C inhibitors, with the STAT3 activation sustaining the regrowth of tumor cells under KRAS inhibition and up-regulating HLA-B transcription to dampen the cytotoxicity of infiltrated NK cells.

Novel inhibitors of STAT3: an updated patent review (2022-present)

INTRODUCTION

Signal transducer and activator of transcription 3 (STAT3), a member of the STAT protein family, serves as both a signal transducer and a transcription factor. Previous studies have highlighted its pivotal roles in regulating cell proliferation, differentiation, apoptosis, as well as immune and inflammatory responses. Consequently, targeting STAT3 has emerged as a promising therapeutic strategy for addressing related diseases.

AREAS COVERED

This review offers a comprehensive summary of the progress in discovering STAT3 inhibitors, with a focus on their structural diversity and structure-activity relationships as presented in patent literature from 2022 to the present.

EXPERT OPINION

Over the past decades, significant progress has transformed STAT3 into a target of interest for drug development. Despite these advances, no STAT3-targeting drugs have successfully progressed through late-phase clinical trials, largely due to challenges such as limited selectivity and undesirable side effects. These obstacles highlight the inherent complexity of developing safe and effective STAT3 inhibitors. Nevertheless, STAT3 remains a highly promising therapeutic target, and ongoing advancements in this field hold the potential to unlock novel strategies for addressing STAT3-related diseases.

Discovery of benzethonium chloride as a potent STAT3 inhibitor for the treatment of HNSCC

Head and neck squamous cell carcinoma (HNSCC) is a prevalent malignancy with high mortality, and effective treatment strategies remain limited. This study investigated the effects of benzethonium chloride (BZN), an FDA-approved anti-infective agent, on HNSCC cell lines and its underlying mechanisms. BZN significantly inhibited the proliferation of HNSCC cell lines CAL27 and FaDu and induced apoptosis in both cell lines in vitro. In a subcutaneous tumor model, BZN markedly suppressed tumor growth in the mouse HNSCC cell line MOC1. Mechanistically, BZN may directly bind to the SH2 domain of STAT3, inhibit its dimerization, prevent the nuclear translocation of phosphorylated STAT3 (p-STAT3), downregulate the expression of the downstream protein MCL-1, and induce mitochondrial-mediated apoptosis in FaDu and CAL27 cells. These findings highlight BZN as a potential therapeutic agent for HNSCC, offering a novel approach to improve treatment outcomes in clinical settings.

M13, an anthraquinone compound isolated from Morinda officinalis alleviates the progression of the osteoarthritis via the regulation of STAT3

BACKGROUND

Osteoarthritis (OA) is characterized by the progressive deterioration of articular cartilage, leading to joint pain and functional impairment. OA severely impacts quality of life and presents a substantial societal burden. Currently, effective treatment options remain limited. Morinda officinalis (MO), a traditional Chinese herb, is commonly used to treat rheumatoid arthritis and alleviate joint pain. M13, an anthraquinone extracted from MO, has shown significant anti-inflammatory properties, making it a promising candidate for the treatment of OA. However, its role in inhibiting OA progression and the mechanisms involved remain poorly understood.

PURPOSE

The objective of this study is to examine the impact of M13 on osteoarthritis and uncover the mechanisms.

METHODS

The effects of M13 on OA were assessed using TNF-α induced chondrocyte models and mice with destabilization of the medial meniscus (DMM). Celecoxib was used as a positive control. We evaluated the expression of factors related to chondrocyte degeneration and inflammation through qRT-PCR, immunoblotting, and immunofluorescence. Chondrocyte viability was measured using CCK-8 assays, EdU staining, and flow cytometry. Molecular docking, molecular dynamics simulations and isothermal titration calorimetry (ITC) were performed to evaluate the binding efficacy of target proteins. Additionally, the therapeutic effects of M13 in OA mice were confirmed through in vivo experiments.

RESULTS

In primary murine chondrocytes, M13 rescued TNF-α-induced matrix degradation and loss of vitality while suppressing ROS generation. Mechanistically, STAT3 was identified as a target protein of M13, through which M13 mitigated OA by inhibiting the STAT3 signaling pathway. Further in vivo experiments demonstrated that M13 reduced the scores of the Osteoarthritis Research Society International (OARSI), alleviating cartilage impairment. M13 enhanced levels of collagen II and aggrecan in cartilage tissue while decreasing the amounts of cartilage-degrading proteins ADAMTS-5 and MMP13.

CONCLUSION

This is the first study to validate that M13 mitigates the inflammation and damage in cartilage tissue by blocking the STAT3 signaling pathway. These findings hold promise for enhancing innovative clinical interventions targeting OA.

Research progress of SHP-1 agonists as a strategy for tumor therapy

Src homology-2 domain-containing protein tyrosine phosphatase 1 (SHP-1) is a member of protein tyrosine phosphatase (PTP) family, and serves as a crucial negative regulator of various oncogenic signaling pathways. The development of SHP-1 agonists has garnered extensive research attention and is considered as a promising strategy for treating tumors. In this review, we comprehensively analyze the advancements of SHP-1 agonists, focusing on their structures and biological activities. Based on the structure skeletons, we classify these SHP-1 agonists as kinase inhibitors, sorafenib derivatives, obatoclax derivatives, lithocholic acid derivatives and thieno[2,3-b]quinoline derivatives. Additionally, we discuss the potential opportunities and challenges for developing SHP-1 agonists. It is hoped that this review will provide inspiring insights into the discovery of drugs targeting SHP-1.