Targeting transcription factor STAT3 for cancer prevention and therapy

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.

Ruxolitinib suppresses tumor growth in PTEN-deficient glioblastoma by inhibiting the STAT3-PDL1 axis-mediated the M2 polarization of macrophages

BACKGROUND

Glioblastoma (GBM) is the most malignant form of brain tumor, and GBM patients with poorer prognosis and highly immunosuppressive tumor microenvironment (TME) often exhibit PTEN deficiency in their tumor tissues. Therefore, new therapeutic strategies targeting immunosuppressive TME maybe useful in PTEN-deficient GBM.

METHODS

Bioinformatics was used to assess gene expression, survival time and immunoinfiltration in PTEN-deficient GBM. CRISPR-Cas9 was used to construct gene knockout cell lines. C57BL/6 mouse orthotopic GBM models were used to conduct survival analysis and evaluate treatment effect of Ruxolitinib. Flow cytometry, immunohistochemistry, immunofluorescence and quantitative real-time PCR (qRT-PCR) to detect the polarization of macrophages. Immunoblotting, immunohistochemistry, qRT-PCR, enzyme linked immunosorbent assay, and dual-luciferase reporter assay were used to conduct mechanism research.

RESULTS

We identified that the elevated levels of phosphorylated STAT3 (p-STAT3) in PTEN-deficient GBM facilitate PDL1 transcription, which subsequently drives M2 polarization of macrophages. Furthermore, PTEN deficiency, along with high expression levels of STAT3 and PDL1, are associated with a shorter survival time in GBM patients. Notably, in orthotopic mouse models of GBM with PTEN deficiency, Ruxolitinib therapy reduces the levels of p-STAT3 and PDL1, inhibits the infiltration of M2 macrophages, and suppresses tumor growth.

CONCLUSIONS

The STAT3-PDL1 axis plays a crucial role in the M2 polarization of macrophages in PTEN-deficient GBM. The blockade of the STAT3-PDL1 axis by Ruxolitinib regulates the anti-tumor immune response and curtails tumor progression in PTEN-deficient GBM, highlighting its significant clinical implications.

Low Expression of GRIM-19 Correlates with Poor Prognosis in Patients with Upper Urinary Tract Urothelial Carcinoma

PURPOSE

This study aimed to clarify the expression of a gene associated with Retinoid- Interferon-Induced Mortality-19 (GRIM-19) in Upper Urinary Tract Urothelial Carcinoma (UUTUC) and its prognostic significance for UUTUC patients.

MATERIALS AND METHODS

Immunohistochemical (IHC) staining was used to determine the GRIM-19 expression in 70 paired samples. Progression-Free Survival (PFS) and Cancer-Specific Survival (CSS) were assessed using the Kaplan-Meier method. The independent prognostic factors for PFS and CSS were analyzed by multivariable Cox regression models.

RESULTS

IHC staining showed that GRIM-19 expression was significantly decreased in UUTUC, and its cellular location changed from being both cytoplasmic and nuclear to only cytoplasmic. Kaplan- Meier analysis revealed that the patients with tumors expressing low GRIM-19 had a significantly higher risk for tumor progression (P = 0.002) and cancer-specific mortality (P < 0.001) compared to those with high GRIM-19 levels. The Cox regression showed that both GRIM-19 expression (P = 0.025) and lymph node metastasis (LN) (P = 0.007) were independent predictors of progression in the muscle-invasive (MIC) subgroup. GRIM-19 expressions (entire cohort: P = 0.011; MIC subgroup: P = 0.025), LN (entire cohort: P = 0.019; MIC subgroup: P = 0.007), and progression (entire cohort: P < 0.001; MIC subgroup: P < 0.001) were independent predictors of cancer-specific survival.

CONCLUSION

Low expression of GRIM-19 in patients with UUTUC had significantly shorter PFS or CSS compared to those with high GRIM-19-expressing tumors. High GRIM-19 expression was also strongly associated with longer PFS in MIC patients. It indicates that GRIM-19 might serve as a promising prognostic biomarker for UUTUC patients.

MicroRNA-450b-5p modulated RPLP0 promotes hepatocellular carcinoma progression via activating JAK/STAT3 pathway

Hepatocellular carcinoma (HCC) is distinguished by its insidious onset, difficult treatment, and poor prognosis. Ribosomal Protein Lateral Stalk Subunit P0 (RPLP0) is implicated in numerous tumor progression processes. Nevertheless, the regulatory mechanism of RPLP0 in HCC progression remains unclear. Our study suggested that RPLP0 exhibits high expression levels in HCC and possesses promising diagnostic capabilities, as indicated by its area under the curve (AUC) of 0.908. Further analysis showed that RPLP0 was a significant independent prognostic factor, and elevated expression levels of RPLP0 were linked with poorer overall survival (OS) and progression-free interval (PFI) outcomes. Additionally, reducing RPLP0 levels led to a decrease in HCC cell proliferation, clonality, invasion, migration, and xenograft tumor growth, as well as an increase in apoptosis. Furthermore, our findings indicated that microRNA(miR)-450b-5p induced downregulation of RPLP0, leading to the suppression of the JAK/STAT3 pathway and consequently hindering the advancement of HCC. The study indicates that RPLP0 plays a role as a carcinogenic factor in HCC and carries important diagnostic and prognostic implications. Targeting the miR-450b-5p/RPLP0/JAK/STAT3 axis has potential clinical value in treating HCC.

Targeting STAT3 signaling pathway in the treatment of Alzheimer's disease with compounds from natural products

Alzheimer's disease (AD) is a neurodegenerative disorder that is difficult to cure and of global concern. Neuroinflammation is closely associated with the onset and progression of AD, making its treatment increasingly important. Compounds from natural products, with fewer side effects than synthetic drugs, are of high research interest. STAT3, a multifunctional transcription factor, is involved in various cellular processes including inflammation, cell growth, and apoptosis. Its activation and inhibition can have different effects under various pathological conditions. In AD, the STAT3 protein plays a crucial role in promoting neuroinflammation and contributing to disease progression. This occurs primarily through the JAK2-STAT3 signaling pathway, which impacts microglia, astrocytes, and hippocampal neurons. This paper reviews the STAT3 signaling pathway in AD and 25 compounds targeting STAT3 up to 2024. Notably, Rutin, Paeoniflorin, and Geniposide up-regulate STAT3 in hippocampal and cortex neurons, showing neuroprotective effects in various AD models. Other 23 compounds downregulate AD by suppressing neuroinflammation through inhibition of STAT3 activation in microglia and astrocytes. These findings highlight the potential of compounds from natural products in improving AD by targeting STAT3, offering insights into the prevention and management of AD.

The LINC00319 binding to STAT3 promotes the cell proliferation, migration, invasion and EMT process in oral squamous cell carcinoma

BACKGROUND

Long non-coding RNA LINC00319 has been implicated in the progression of various cancers, including oral squamous cell carcinoma (OSCC). While our previous work has revealed some aspects of LINC00319's role in OSCC, including its upregulation and involvement in a competing endogenous RNA (ceRNA) mechanism, the full extent of its functions and regulatory mechanisms in OSCC progression remain to be fully elucidated.

OBJECTIVE

This study aimed to investigate the function of LINC00319 in OSCC and its potential interaction with the STAT3 signaling pathway, thus uncovering novel regulatory mechanisms and therapeutic targets.

METHODS

Bioinformatics analysis was performed using TCGA data to evaluate LINC00319 expression in OSCC tissues and its correlation with STAT3 signaling. The direct binding between LINC00319 and STAT3 was examined by RNA pull-down, FISH, and RIP assays. Functional experiments, including CCK-8, transwell migration and invasion assays, and western blot analysis of EMT markers and STAT3 pathway activation, were conducted to assess the effects of LINC00319 on OSCC cell behaviors and its interaction with the STAT3 signaling pathway. In vivo xenograft models were established to validate the role of LINC00319 in tumor growth and STAT3 activation.

RESULTS

LINC00319 expression was significantly upregulated in OSCC tissues compared to normal tissues, and high LINC00319 expression correlated with STAT3 signaling activation. Mechanistically, LINC00319 directly bound to STAT3 protein and promoted its phosphorylation at Tyr705. LINC00319 overexpression enhanced, while its knockdown suppressed, the proliferation, migration, invasion, and EMT of OSCC cells. These oncogenic effects were mediated through STAT3 activation and could be reversed by the STAT3 inhibitor stattic. In vivo experiments further confirmed that LINC00319 silencing inhibited tumor growth and STAT3 phosphorylation.

CONCLUSION

This study uncovers that LINC00319 promotes OSCC tumorigenesis by directly binding to and activating STAT3 signaling. These findings provide new insights into the regulatory mechanisms of STAT3 by long non-coding RNAs and highlight the potential of LINC00319 as a biomarker and therapeutic target in OSCC.

STAT3: Key targets of growth-promoting receptor positive breast cancer

Breast cancer has become the malignant tumor with the first incidence and the second mortality among female cancers. Most female breast cancers belong to luminal-type breast cancer and HER2-positive breast cancer. These breast cancer cells all have different driving genes, which constantly promote the proliferation and metastasis of breast cancer cells. Signal transducer and activator of transcription 3 (STAT3) is an important breast cancer-related gene, which can promote the progress of breast cancer. It has been proved in clinical and basic research that over-expressed and constitutively activated STAT3 is involved in the progress, proliferation, metastasis and chemotherapy resistance of breast cancer. STAT3 is an important key target in luminal-type breast cancer and HER2-positive cancer, which has an important impact on the curative effect of related treatments. In breast cancer, the activation of STAT3 will change the spatial position of STAT3 protein and cause different phenotypic changes of breast cancer cells. In the current basic research and clinical research, small molecule inhibitors activated by targeting STAT3 can effectively treat breast cancer, and enhance the efficacy level of related treatment methods for luminal-type and HER2-positive breast cancers.

The Syvn1 inhibits neuronal cell ferroptosis by activating Stat3/Gpx4 axis in rat with spinal cord injury

Spinal cord injury (SCI) leads to secondary neuronal death, which severely impedes recovery of motor function. Therefore, prevention of neuronal cell death after SCI is an important strategy. Ferroptosis, a new form of cell death discovered in recent years, has been shown to be involved in the regulation of SCI. However, the role and potential mechanisms of ferroptosis in secondary SCI are not fully understood. In this study, we report that the E3 ubiquitin ligase Syvn1 suppresses ferroptosis and promotes functional recovery from SCI in vitro and in vivo. Mechanistically, screened with bioinformatics, immunoprecipitation, and mass spectrometry, we identified Stat3, a transcription factor that induces the expression of the ferroptosis inhibitor Gpx4, as a substrate of Syvn1. Furthermore, we identified neurons as the primary cellular source of Syvn1 signalling. Moreover, we determined the binding domains of Syvn1 and Stat3 in HEK 293 T cells using full-length proteins and a series of truncated Flag-tagged and Myc-tagged fragments. Furthermore, we created the cell and animal models with silencing or overexpression of Syvn1 and Stat3 and found that Syvn1 inhibits neuronal ferroptosis by stabilizing Stat3, which subsequently activates the ferroptosis regulator Gpx4 in SCI. In summary, the Syvn1-mediated Stat3/Gpx4 signalling axis attenuates neuronal ferroptosis, reduces neuronal death, and promotes SCI repair. Therefore, our findings provide potential new targets and intervention strategies for the treatment of SCI.

STAT3 Protein-Protein Interaction Analysis Finds P300 as a Regulator of STAT3 and Histone 3 Lysine 27 Acetylation in Pericytes

BACKGROUND

Signal transducer and activator of transcription 3 (STAT3) is a member of the cytoplasmic inducible transcription factors and plays an important role in mediating signals from cytokines, chemokines, and growth factors. We and others have found that STAT3 directly regulates pro-fibrotic signaling in the kidney. The STAT3 protein-protein interaction plays an important role in activating its transcriptional activity. It is necessary to identify these interactions to investigate their function in kidney disease. Here, we investigated the protein-protein interaction among three species to find crucial interactions that can be targeted to alleviate kidney disease.

METHOD

In this study, we examined common protein-protein interactions leading to the activation or downregulation of STAT3 among three different species: humans (Homo sapiens), mice (Mus musculus), and rabbits (Oryctolagus cuniculus). Further, we chose to investigate the P300 and STAT3 interaction and performed studies of the activation of STAT3 using IL-6 and inhibition of the P300 by its specific inhibitor A-485 in pericytes. Next, we performed immunoprecipitation to confirm whether A-485 inhibits the binding of P300 to STAT3.

RESULTS

Using the STRING application from ExPASy, we found that six proteins, including PIAS3, JAK1, JAK2, EGFR, SRC, and EP300, showed highly confident interactions with STAT3 in humans, mice, and rabbits. We also found that IL-6 treatment increased the acetylation of STAT3 and increased histone 3 lysine acetylation (H3K27ac). Furthermore, we found that the disruption of STAT3 and P300 interaction by the P300 inhibitor A-485 decreased STAT3 acetylation and H3K27ac. Finally, we confirmed that the P300 inhibitor A-485 inhibited the binding of STAT3 with P300, which inhibited its transcriptional activity by reducing the expression of Ccnd1 (Cyclin D1).

CONCLUSIONS

Targeting the P300 protein interaction with STAT3 may alleviate STAT3-mediated fibrotic signaling in humans and other species.

Early growth response protein 2 promotes partial epithelial-mesenchymal transition by phosphorylating Smad3 during renal fibrosis

Chronic kidney disease (CKD) is a serious health problem worldwide, which ultimately leads to end-stage renal disease (ESRD). Renal fibrosis is the common pathway and major pathological manifestation for various CKD proceeding to ESRD. However, the underlying mechanisms and effective therapies are still ambiguous. Early growth response 2 (EGR2) is reportedly involved in organ formation and cell differentiation. To determine the role of EGR2 in renal fibrosis, we respectively confirmed the increased expression of EGR2 in kidney specimens from both CKD patients and mice with location in proximal tubules. Genetic deletion of EGR2 attenuated obstructive nephropathy while EGR2 overexpression further promoted renal fibrosis in mice subjected to unilateral ureteral obstruction (UUO) due to extracellular matrix (ECM) deposition mediating by partial epithelial-mesenchymal transition (EMT) as well as imbalance between matrix metalloproteinases (MMPs) and tissue inhibitor of MMPs (TIMPs). We found that EGR2 played a critical role in Smad3 phosphorylation, and inhibition of EGR2 reduced partial EMT leading to blockade of ECM accumulation in cultured human kidney 2 cells (HK2) treated with transforming growth factor β1 (TGF-β1). In addition, the transcription co-stimulator signal transducer and activator of transcription 3 (STAT3) phosphorylation was confirmed to regulate the transcription level of EGR2 in TGF-β1-induced HK2 cells. In conclusion, this study demonstrated that EGR2 played a pathogenic role in renal fibrosis by a p-STAT3-EGR2-p-Smad3 axis. Thus, targeting EGR2 could be a promising strategy for CKD treatment.

BertSNR: an interpretable deep learning framework for single-nucleotide resolution identification of transcription factor binding sites based on DNA language model

MOTIVATION

Transcription factors are pivotal in the regulation of gene expression, and accurate identification of transcription factor binding sites (TFBSs) at high resolution is crucial for understanding the mechanisms underlying gene regulation. The task of identifying TFBSs from DNA sequences is a significant challenge in the field of computational biology today. To address this challenge, a variety of computational approaches have been developed. However, these methods face limitations in their ability to achieve high-resolution identification and often lack interpretability.

RESULTS

We propose BertSNR, an interpretable deep learning framework for identifying TFBSs at single-nucleotide resolution. BertSNR integrates sequence-level and token-level information by multi-task learning based on pre-trained DNA language models. Benchmarking comparisons show that our BertSNR outperforms the existing state-of-the-art methods in TFBS predictions. Importantly, we enhanced the interpretability of the model through attentional weight visualization and motif analysis, and discovered the subtle relationship between attention weight and motif. Moreover, BertSNR effectively identifies TFBSs in promoter regions, facilitating the study of intricate gene regulation.

AVAILABILITY AND IMPLEMENTATION

The BertSNR source code can be found at https://github.com/lhy0322/BertSNR.

Prognostic role of SOX2 and STAT3 expression on circulating T lymphocytes and CD44+/CD24neg cells in the locally advanced and metastatic breast cancer

BACKGROUND

Breast cancer (BC) is associated with a continuous increase in incidence, with high mortality rates in several countries. CD44, STAT3, and SOX2 are related to regulating of somatic cell division, tumorigenesis, and metastasis in BC.

METHODS

A cross-sectional study was carried out at the Hospital de Cancer de Pernambuco (HCP) between 2017 and 2018. Fifty-one women with locally advanced (LA) and 14 with metastatic BC were included in the study.

RESULTS

High CD44+/CD24neg and CD44+/CD24neg/SOX2+ levels in Luminal B (LB), HER2+, and triple-negative breast cancer (TNBC) compared with controls (p < 0.05). Low CD44+/CD24negSTAT3+ levels in LB, HER2+, and TNBC compared with controls (p < 0.05). High T lymphocytes, and low STAT3 + T, and SOX2 + T levels in BC patients (p < 0.05). High SOX2 + T levels in patients with axillary lymph node-negative (N0) compared with the axillary lymph node-positives (N1 and N2 groups; p < 0.05). High SOX2 + T levels in N1 compared to N2 (p < 0.05). High T lymphocytes and low SOX2 + T levels in the LA tumor compared to metastatic disease (p = 0.0007 and p = 0.02, respectively). High CD44 + /CD24negSTAT3+, and T lymphocyte levels in TNBC patients with LA tumor compared to metastatic (p < 0.05). Low STAT3 + T levels in TBNC patients with LA tumor compared to metastatic (p = 0.0266).

CONCLUSION

SOX2 and STAT3 expression on circulating T lymphocytes and CD44 + /CD24neg cells in peripheral blood have prognostic roles in breast cancer. SOX2 and STAT3 expression are potential predictive biomarkers of disease progression in breast cancer regardless of tumor subtype.

Blocking senescence and tolerogenic function of dendritic cells induced by γδ Treg cells enhances tumor-specific immunity for cancer immunotherapy

BACKGROUND

Regulatory T (Treg) cells are a key component in maintaining the suppressive tumor microenvironment and immune suppression in different types of cancers. A precise understanding of the molecular mechanisms used by Treg cells for immune suppression is critical for the development of effective strategies for cancer immunotherapy.

METHODS

Senescence development and tolerogenic functions of dendritic cells (DCs) induced by breast cancer tumor-derived γδ Treg cells were fully characterized using real-time PCR, flow cytometry, western blot, and functional assays. Loss-of-function strategies with pharmacological inhibitor and/or neutralizing antibody were used to identify the potential molecule(s) and pathway(s) involved in DC senescence and dysfunction induced by Treg cells. Impaired tumor antigen HER2-specific recognition and immune response of senescent DCs induced by γδ Treg cells were explored in vitro and in vivo in humanized mouse models. In addition, the DC-based HER2 tumor vaccine immunotherapy in breast cancer models was performed to explore the enhanced antitumor immunity via prevention of DC senescence through blockages of STAT3 and programmed death-ligand 1 (PD-L1) signaling.

RESULTS

We showed that tumor-derived γδ Treg cells promote the development of senescence in DCs with tolerogenic functions in breast cancer. Senescent DCs induced by γδ Treg cells suppress Th1 and Th17 cell differentiation but promote the development of Treg cells. In addition, we demonstrated that PD-L1 and STAT3 signaling pathways are critical and involved in senescence induction in DCs mediated by tumor-derived γδ Treg cells. Importantly, our complementary in vivo studies further demonstrated that blockages of PD-L1 and/or STAT3 signaling can prevent γδ Treg-induced senescence and reverse tolerogenic functions in DCs, resulting in enhanced HER2 tumor-specific immune responses and immunotherapy efficacy in human breast cancer models.

CONCLUSIONS

These studies not only dissect the suppressive mechanism mediated by tumor-derived γδ Treg cells on DCs in the tumor microenvironment but also provide novel strategies to prevent senescence and dysfunction in DCs and enhance antitumor efficacy mediated by tumor-specific T cells for cancer immunotherapy.

PQR309, a dual PI3K/mTOR inhibitor, synergizes with gemcitabine by impairing the GSK-3β and STAT3/HSP60 signaling pathways to treat nasopharyngeal carcinoma

End-stage nasopharyngeal carcinoma (NPC) has unsatisfactory survival. The limited benefit of chemotherapy and the scarcity of targeted drugs are major challenges in NPC. New approaches to treat late-stage NPC are urgently required. In this study, we explored whether the dual PI3K/mTOR inhibitor, PQR309, exerted a favorable antineoplastic effect and sensitized the response to gemcitabine in NPC. We observed that PI3K expression was positive and elevated in 14 NPC cell lines compared with that in normal nasopharygeal cell lines. Patients with NPC with higher PI3K levels displayed poorer prognosis. We subsequently showed that PQR309 alone effectively decreased the viability, invasiveness, and migratory capability of NPC cells and neoplasm development in mice xenograft models, and dose-dependently induced apoptosis. More importantly, PQR309 remarkably strengthened the anti-NPC function of gemcitabine both in vivo and in vitro. Mechanistically, PQR309 sensitized NPC to gemcitabine by increasing caspase pathway-dependent apoptosis, blocking GSK-3β and STAT3/HSP60 signaling, and ablating epithelial-mesenchyme transition. Thus, targeting PI3K/mTOR using PQR309 might represent a treatment option to promote the response to gemcitabine in NPC, and provides a theoretical foundation for the study of targeted drugs combined with chemotherapy for NPC.

Cell plasticity modulation by flavonoids in resistant breast carcinoma targeting the nuclear factor kappa B signaling

Cancer cell plasticity plays a crucial role in tumor initiation, progression, and metastasis and is implicated in the multiple cancer defense mechanisms associated with therapy resistance and therapy evasion. Cancer resistance represents one of the significant obstacles in the clinical management of cancer. Some reversal chemosensitizing agents have been developed to resolve this serious clinical problem, but they have not yet been proven applicable in oncological practice. Activated nuclear factor kappa B (NF-κB) is a frequently observed biomarker in chemoresistant breast cancer (BC). Therefore, it denotes an attractive cellular target to mitigate cancer resistance. We summarize that flavonoids represent an essential class of phytochemicals that act as significant regulators of NF-κB signaling and negatively affect the fundamental cellular processes contributing to acquired cell plasticity and drug resistance. In this regard, flavokawain A, icariin, alpinetin, genistein, wogonin, apigenin, oroxylin A, xanthohumol, EGCG, hesperidin, naringenin, orientin, luteolin, delphinidin, fisetin, norwogonin, curcumin, cardamonin, methyl gallate and catechin-3-O-gallate, ampelopsin, puerarin, hyperoside, baicalein, paratocarpin E, and kaempferol and also synthetic flavonoids such as LFG-500 and 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone have been reported to specifically interfere with the NF-κB pathway with complex signaling consequences in BC cells and could be potentially crucial in re-sensitizing unresponsive BC cases. The targeting NF-κB by above-mentioned flavonoids includes the modification of tumor microenvironment and epithelial-mesenchymal transition, growth factor receptor regulations, and modulations of specific pathways such as PI3K/AKT, MAP kinase/ERK, and Janus kinase/signal transduction in BC cells. Besides that, NF-κB signaling in BC cells modulated by flavonoids has also involved the regulation of ATP-binding cassette transporters, apoptosis, autophagy, cell cycle, and changes in the activity of cancer stem cells, oncogenes, or controlling of gene repair. The evaluation of conventional therapies in combination with plasticity-regulating/sensitizing agents offers new opportunities to make significant progress towards a complete cure for cancer.

Farnesoid X receptor promotes non-small cell lung cancer metastasis by activating Jak2/STAT3 signaling via transactivation of IL-6ST and IL-6 genes

Metastasis accounts for the majority of cases of cancer recurrence and death in patients with advanced non-small cell lung cancer (NSCLC). Farnesoid X Receptor (FXR) is a bile acid nuclear receptor that was recently found to be upregulated in NSCLC tissues. However, whether and how FXR regulates NSCLC metastasis remains unclear. In the present study, it was found that FXR promoted the migration, invasion, and angiogenic ability of NSCLC cells in vitro, and increased NSCLC metastasis in a mouse model in vivo. Mechanistic investigation demonstrated that FXR specifically bound to the promoters of IL-6ST and IL-6 genes to upregulate their transcription, thereby leading to activation of the Jak2/STAT3 signaling pathway, which facilitated tumor migration, invasion, and angiogenesis in NSCLC. Notably, Z-guggulsterone, a natural FXR inhibitor, significantly reduced FXRhigh NSCLC metastasis, and decreased the expression of FXR, IL-6, IL-6ST, and p-STAT3 in the mouse model. Clinical analysis verified that FXR was positively correlated with IL-6, IL-6ST and p-STAT3 expression in NSCLC patients, and was indicative of a poor prognosis. Collectively, these results highlight a novel FXR-induced IL-6/IL-6ST/Jak2/STAT3 axis in NSCLC metastasis, and a promising therapeutic means for treating FXRhigh metastatic NSCLC.

Recent research progress of circular RNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an extremely heterogeneous malignant tumor with a high morbidity and mortality. Circular RNAs (circRNAs) are noncoding RNAs with high stability, organ/tissue/cell-specific expression and are conserved across species. Accumulating evidence suggested that circRNAs play crucial roles as microRNA sponges, protein sponges, scaffolds, recruiters and could even polypeptide encoders. Many studies have since revealed that circRNAs were aberrantly expressed in HCC and acted as crucial modulators of HCC carcinogenesis and progression. Furthermore, circRNAs have also been identified as potential diagnostic and prognostic biomarkers for HCC. In this review, we thoroughly outline and evaluate the function of circRNAs in HCC development, with an emphasis on the specific molecular pathways by which they participated in the formation and progression of HCC, and we address their potential for serving as clinical biomarkers in HCC.

Interfering with the AKT/mTOR/STAT3/ID1 signaling axis with usenamine A restrains the proliferative and invasive potential of human hepatocellular carcinoma cells

BACKGROUND

Usenamine A, a novel natural compound initially isolated from the lichen Usnea longissima, has exhibited promising efficacy against hepatoma in prior investigation. Nevertheless, the underlying mechanisms responsible for its antihepatoma effects remain unclear. Furthermore, the role of the AKT/mechanistic target of the rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3)/inhibitor of differentiation/DNA binding 1 (ID1) signaling axis in hepatocellular carcinoma (HCC), and the potential anti-HCC effects of drugs targeting this pathway are not well understood.

METHODS

CCK-8 assay was used to investigate the effects of usenamine A on the proliferation of human HCC cells. Moreover, the effects of usenamine A on the invasion ability of human HCC cells were evaluated by transwell assay. In addition, expression profiling analysis, quantitative real-time PCR, immunoblotting, immunohistochemistry (IHC) analysis, RNAi, immunoprecipitation, and chromatin immunoprecipitation (ChIP) assay were used to explore the effects of usenamine A on the newly identified AKT/mTOR/STAT3/ID1 signaling axis in human HCC cells.

RESULTS

Usenamine A inhibited the proliferation and invasion of human HCC cell lines (HepG2 and SK-HEP-1). Through the analysis of gene expression profiling, we identified that usenamine A suppressed the expression of ID1 in human HCC cells. Furthermore, immunoprecipitation experiments revealed that usenamine A facilitated the degradation of the ID1 protein via the ubiquitin-proteasome pathway. Moreover, usenamine A inhibited the activity of STAT3 in human HCC cells. ChIP analysis demonstrated that STAT3 positively regulated ID1 expression at the transcriptional level in human HCC cells. The STAT3/ID1 axis played a role in mediating the anti-proliferative and anti-invasive impacts of usenamine A on human HCC cells. Additionally, usenamine A suppressed the STAT3/ID1 axis through AKT/mTOR signaling in human HCC cells.

CONCLUSION

Usenamine A displayed robust anti-HCC potential, partly attributed to its capacity to downregulate the AKT/mTOR/STAT3/ID1 signaling pathway and promote ubiquitin-proteasome-mediated ID1 degradation. Usenamine A has the potential to be developed as a therapeutic agent for HCC cases characterized by abnormal AKT/mTOR/STAT3/ID1 signaling, and targeting the AKT/mTOR/STAT3 signaling pathway may be a viable option for treating patients with HCC exhibiting elevated ID1 expression.

Sanghuangporus sanghuang extract inhibits the proliferation and invasion of lung cancer cells in vitro and in vivo

BACKGROUND/OBJECTIVES

Sanghuangporus sanghuang (SS) has various medicinal effects, including anti-inflammation and anticancer activities. Despite the extensive research on SS, its molecular mechanisms of action on lung cancer are unclear. This study examined the impact of an SS alcohol extract (SAE) on lung cancer using in vitro and in vivo models.

MATERIALS/METHODS

Different concentrations of SAE were used to culture lung cancer cells (A549 and H1650). A cell counting kit-8 assay was used to detect the survival ability of A549 and H1650 cells. A scratch assay and transwell cell invasion assay were used to detect the migration rate and invasive ability of SAE. Western blot analysis was used to detect the expression of B-cell lymphoma-2 (Bcl-2), Bcl2-associated X (Bax), cyclin D1, cyclin-dependent kinases 4 (CDK4), signal transducer and activator of transcription 3 (STAT3), and phosphorylated STAT3 (p-STAT3). Lung cancer xenograft mice were used to detect the inhibiting ability of SAE in vivo. Hematoxylin and eosin staining and immunohistochemistry were used to detect the effect of SAE on the structural changes to the tumor and the expression of Bcl-2, Bax, cyclin D1, CDK4, STAT3, and p-STAT3 in lung cancer xenograft mice.

RESULTS

SAE could inhibit lung cancer proliferation significantly in vitro and in vivo without cytotoxicity. SAE suppressed the viability, migration, and invasion of lung cancer cells in a dose and time-dependent manner. The SAE treatment significantly decreased the proapoptotic Bcl-2/Bax ratio and the expression of pro-proliferative proteins Cyclin D1 and CDK4 in vitro and in vivo. Furthermore, SAE also inhibited STAT3 expression.

CONCLUSIONS

SAE reduced the cell viability and suppressed cell migration and invasion in human lung cancer cells. Moreover, SAE also exhibited anti-proliferation effects in vivo. Therefore, SAE may have benefits in cancer therapy.

Uncovering the mechanism of Qidan Dihuang Granule in the treatment of diabetic kidney disease combined network pharmacology, UHPLC-MS/MS with experimental validation

Background and aim

Diabetic Kidney Disease (DKD) is a common microvascular complication of diabetes mellitus. Multi-center, randomized controlled trials have shown that Qidan Dihuang Granule (QDDHG) reduces the levels of albuminuria of DKD. However, the specific mechanisms of QDDHG on DKD are not clarified. Thus, this study utilized network pharmacology, UHPLC-MS/MS (Ultra-High Performance Liquid Chromatography - Mass Spectrometry) and animal experiments to reveal the mechanisms of QDDHG on DKD.

Experimental procedure

Screening and retrieving active ingredients and corresponding targets of QDDHG on DKD through the TCMSP, ETCM, Disgenet, GeneCards, Omim and DrugBank databases. The PPI were performed with BioGrid, STRING, OmniPath, InWeb-IM. AutoDock Vina molecular docking module to estimate the validation from the compounds and target proteins. Free energy to estimate the binding affinity for identified compounds and target proteins. The ingredients of QDDHG were analyzed utilizing UHPLC-MS/MS. In vivo experiment with db/db mice were used to verify the targets and pathway predicted by network pharmacology.

Results and conclusion

The results demonstrated that QDDHG has 18 active compounds and 13 target proteins of QDDHG exerted a crucial role in treatment of DKD. QDDHG affect the multiple biological processes included cellular response to lipid, response to oxidative stress, and various pathways, such as AGE-RAGE, PI3K-Akt, MAPK, TNF, EGFR, STAT3. The results of UHPLC-MS/MS showed that six ingredients predicted by network pharmacology were also verified in experiment. In vivo experiment verified the effects of QDDHG on protecting the renal function mainly through inhibited the expression of EGFR, STAT3 and pERK in the db/db mice.

Filamentous Fungi-Derived Orsellinic Acid-Sesquiterpene Meroterpenoids: Fungal Sources, Chemical Structures, Bioactivities, and Biosynthesis

Fungi-derived polyketide-terpenoid hybrids are important meroterpenoid natural products that possess diverse structure scaffolds with a broad spectrum of bioactivities. Herein, we focus on an ever-increasing group of meroterpenoids, orsellinic acid-sesquiterpene hybrids comprised of biosynthetic start unit orsellinic acid coupling to a farnesyl group or/and its modified cyclic products. The review entails the search of China National Knowledge Infrastructure (CNKI), Web of Science, Science Direct, Google Scholar, and PubMed databases up to June 2022. The key terms include "orsellinic acid", "sesquiterpene", "ascochlorin", "ascofuranone", and "Ascochyta viciae", which are combined with the structures of "ascochlorin" and "ascofuranone" drawn by the Reaxys and Scifinder databases. In our search, these orsellinic acid-sesquiterpene hybrids are mainly produced by filamentous fungi. Ascochlorin was the first compound reported in 1968 and isolated from filamentous fungus Ascochyta viciae (synonym: Acremonium egyptiacum; Acremonium sclerotigenum); to date, 71 molecules are discovered from various filamentous fungi inhabiting in a variety of ecological niches. As typical representatives of the hybrid molecules, the biosynthetic pathway of ascofuranone and ascochlorin are discussed. The group of meroterpenoid hybrids exhibits a broad arrange of bioactivities, as highlighted by targeting hDHODH (human dihydroorotate dehydrogenase) inhibition, antitrypanosomal, and antimicrobial activities. This review summarizes the findings related to the structures, fungal sources, bioactivities, and their biosynthesis from 1968 to June 2022.

Discovery, Optimization, and Evaluation of Novel N-(Benzimidazol-5-yl)-1,3,4-thiadiazol-2-amine Analogues as Potent STAT3 Inhibitors for Cancer Treatment

Signal transducer and activator of transcription 3 (STAT3) is an attractive target for cancer therapy. However, identifying potent and selective STAT3 small-molecule inhibitors with drug-like properties remains challenging. Based on a scaffold combination strategy, compounds with a novel N-(benzimidazol-5-yl)-1,3,4-thiadiazol-2-amine scaffold were designed and their inhibition of the interleukin-6 (IL-6)/JAK/STAT3 pathway was tested in HEK-Blue IL-6 reporter cells. After optimization of lead compound 12, compound 40 was identified as a selective STAT3 inhibitor that directly binds the SH2 domain to inhibit STAT3 phosphorylation, translocation, and downstream gene transcription. Compound 40 exhibited antiproliferative activities against STAT3-overactivated DU145 (IC50 value = 2.97 μM) and MDA-MB-231 (IC50 value = 3.26 μM) cancer cells and induced cell cycle arrest and apoptosis. In the DU145 xenograft model, compound 40 showed in vivo antitumor efficacy following intraperitoneal administration, with a tumor growth inhibition rate of 65.3% at 50 mg/kg, indicating promise for further development.

Preclinical characterization of WB737, a potent and selective STAT3 inhibitor, in natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTL) is an uncommon malignancy with poor prognosis and limited therapeutic options. Activating mutations of signal transducer and activator of transcription 3 (STAT3) are frequently found in patients with NKTL, suggesting that targeted inhibition of STAT3 is a potential therapeutic option for this disease. Here, we have developed a small molecule drug WB737 as a novel and potent STAT3 inhibitor that directly binds to the STAT3-Src homology 2 domain with high affinity. In addition, the binding affinity of WB737 to STAT3 is 250-fold higher than STAT1 and STAT2. Interestingly, WB737 is more selective for NKTL with STAT3-activating mutations in terms of growth inhibition and apoptotic induction when compared with Stattic. Mechanistically, WB737 inhibits both canonical and noncanonical STAT3 signaling via suppression of STAT3 phosphorylation at Tyr705 and Ser727, respectively, thereby inhibiting the expression of c-Myc and mitochondria-related genes. Moreover, WB737 inhibited STAT3 more potently than Stattic, resulting in a significant antitumor effect with undetectable toxicity, followed by almost complete tumor regression in an NKTL xenograft model harboring a STAT3-activating mutation. Taken together, these findings provide preclinical proof-of-concept for WB737 as a novel therapeutic strategy for the treatment of NKTL patients with STAT3-activating mutations.

Pentagalloyl Glucose: A Review of Anticancer Properties, Molecular Targets, Mechanisms of Action, Pharmacokinetics, and Safety Profile

Pentagalloyl glucose (PGG) is a natural hydrolyzable gallotannin abundant in various plants and herbs. It has a broad range of biological activities, specifically anticancer activities, and numerous molecular targets. Despite multiple studies available on the pharmacological action of PGG, the molecular mechanisms underlying the anticancer effects of PGG are unclear. Here, we have critically reviewed the natural sources of PGG, its anticancer properties, and underlying mechanisms of action. We found that multiple natural sources of PGG are available, and the existing production technology is sufficient to produce large quantities of the required product. Three plants (or their parts) with maximum PGG content were Rhus chinensis Mill, Bouea macrophylla seed, and Mangifera indica kernel. PGG acts on multiple molecular targets and signaling pathways associated with the hallmarks of cancer to inhibit growth, angiogenesis, and metastasis of several cancers. Moreover, PGG can enhance the efficacy of chemotherapy and radiotherapy by modulating various cancer-associated pathways. Therefore, PGG can be used for treating different human cancers; nevertheless, the data on the pharmacokinetics and safety profile of PGG are limited, and further studies are essential to define the clinical use of PGG in cancer therapies.

Research progress of STAT3-based dual inhibitors for cancer therapy

Signal transducer and activator of transcription 3 (STAT3), a transcription factor, regulates gene levels that are associated with cell survival, cell cycle, and immune reaction. It is correlated with the grade of malignancy and the development of various cancers and targeting STAT3 protein is a potentially promising therapeutic strategy for tumors. Over the past 20 years, various compounds have been found to directly inhibit STAT3 activity via different strategies. However, numerous difficulties exist in the development of STAT3 inhibitors, such as serious toxic effects, poor therapeutic effects, and intrinsic and acquired drug resistance. STAT3 inhibitors synergistically suppress cancer development with additional anti-tumor drugs, such as indoleamine 2,3-dioxygenase 1 inhibitors (IDO1i), histone deacetylase inhibitors (HDACi), DNA inhibitors, pro-tumorigenic cytokine inhibitors (PTCi), NF-κB inhibitors, and tubulin inhibitors. Therefore, individual molecule- based dual-target inhibitors can be the candidate alternative or complementary treatment to overcome the disadvantages of just STAT3 or other targets as a monotherapy. In this review, we discuss the theoretical basis for formulating STAT3-based dual-target inhibitors and also summarize their structure-activity relationships (SARs).

Phosphorylation of STAT3 at Tyr705 contributes to TFEB-mediated autophagy-lysosomal pathway dysfunction and leads to ischemic injury in rats

We previously reported that permanent ischemia induces marked dysfunction of the autophagy-lysosomal pathway (ALP) in rats, which is possibly mediated by the transcription factor EB (TFEB). However, it is still unclear whether signal transducer and activator of transcription 3 (STAT3) is responsible for the TFEB-mediated dysfunction of ALP in ischemic stroke. In the present study, we used AAV-mediated genetic knockdown and pharmacological blockade of p-STAT3 to investigate the role of p-STAT3 in regulating TFEB-mediated ALP dysfunction in rats subjected to permanent middle cerebral occlusion (pMCAO). The results showed that the level of p-STAT3 (Tyr705) in the rat cortex increased at 24 h after pMCAO and subsequently led to lysosomal membrane permeabilization (LMP) and ALP dysfunction. These effects can be alleviated by inhibitors of p-STAT3 (Tyr705) or by STAT3 knockdown. Additionally, STAT3 knockdown significantly increased the nuclear translocation of TFEB and the transcription of TFEB-targeted genes. Notably, TFEB knockdown markedly reversed STAT3 knockdown-mediated improvement in ALP function after pMCAO. This is the first study to show that the contribution of p-STAT3 (Tyr705) to ALP dysfunction may be partly associated with its inhibitory effect on TFEB transcriptional activity, which further leads to ischemic injury in rats.

Effects of saponins from Chinese herbal medicines on signal transduction pathways in cancer: A review

Cancer poses a serious threat to human health, and the search for safe and effective drugs for its treatment has aroused interest and become a long-term goal. Traditional Chinese herbal medicine (TCM), an ancient science with unique anti-cancer advantages, has achieved outstanding results in long-term clinical practice. Accumulating evidence shows that saponins are key bioactive components in TCM and have great research and development applications for their significant role in the treatment of cancer. Saponins are a class of glycosides comprising nonpolar triterpenes or sterols attached to hydrophilic oligosaccharide groups that exert antitumor effects by targeting the NF-κB, PI3Ks-Akt-mTOR, MAPK, Wnt-β-catenin, JAK-STAT3, APMK, p53, and EGFR signaling pathways. Presently, few advances have been made in physiological and pathological studies on the effect of saponins on signal transduction pathways involved in cancer treatment. This paper reviews the phytochemistry and extraction methods of saponins of TCM and their effects on signal transduction pathways in cancer. It aims to provide theoretical support for in-depth studies on the anticancer effects of saponins.

Anticancer potential of flaxseed lignans, their metabolites and synthetic counterparts in relation with molecular targets: current challenges and future perspectives

Lignans are known dietary polyphenols found in cereals, plants and seeds. Flaxseed is one of the major sources of lignans mainly existing in the form of secoisolariciresinol diglucoside (SDG) which can be metabolised by the gut microbes into secoisolariciresinol (SECO) and mammalian lignan (enterodiol and enterolactone) that are easily absorbed through the intestines. Numerous studies reveal that flaxseed lignans (FLs) can be promising chemotherapeutics/chemopreventive agents. Their anticancer activity can occur through the induction of apoptosis, inhibition of cell proliferation, and the hindering of metastasis and angiogenesis. The anti-carcinogenesis of flaxseed lignans is achieved through multiple molecular mechanisms involving biochemical entities such as cellular kinases, cell cycle mediators, transcription factors, inflammatory cytokines, reactive oxygen species, and drug transporters. This review summarizes the bioavailability of FLs, their anticancer mechanisms in relevance to molecular targets, safety, and the scope of future research. Overall, FLs can be utilized in functional foods, dietary supplements, and pharmaceuticals for the management and prevention of cancers.

Serine/threonine-protein kinase STK24 induces tumorigenesis by regulating the STAT3/VEGFA signaling pathway

Lung cancer is the most common cause of cancer-related death. Although anti-angiogenesis therapy has been effective in the treatment of nonsmall cell lung cancer (NSCLC), drug-resistance is a common challenge. Therefore, there is a need to develop new therapeutic strategies for NSCLC. Serine/threonine-protein kinase 24 (STK24), also known as MST3, belongs to the germinal center kinase III subfamily, and the biological function of STK24 in NSCLC tumorigenesis and tumor angiogenesis is still unclear. In this study, we demonstrated that STK24 was overexpressed in lung cancer tissues compared with normal lung tissues, and lung cancer patients with higher STK24 expression levels had shorter overall survival time. In addition, our in vitro assays using A549 and H226 cell lines revealed that the STK24 expression level of cancer cells was positively correlated with cancer cells proliferation, migration, invasion, and tumor angiogenesis ability; in vivo assays also demonstrated that silencing of STK24 dramatically inhibited tumor progress and tumor angiogenesis. To investigate a mechanism, we revealed that STK24 positively regulated the signal transducer and activator of transcription 3 (STAT3)/vascular endothelial growth factor A (VEGFA) signaling pathway by inhibiting polyubiquitin-proteasomal-mediated degradation of STAT3. Furthermore, we performed in vivo assays in BALB/c nude mice and in vitro assays to show that STK24-regulated tumor angiogenesis depends on STAT3. These findings deepened our understanding of tumor angiogenesis, and the STK24/STAT3/VEGFA signaling pathway might be a novel therapeutic target for NSCLC treatment.

Role of STAT3 and NRF2 in Tumors: Potential Targets for Antitumor Therapy

Signal transducer and activator of transcription 3 (STAT3) and nuclear factor erythroid-derived 2-like 2 (NRF2, also known as NFE2L2), are two of the most complicated transcription regulators, which participate in a variety of physiological processes. Numerous studies have shown that they are overactivated in multiple types of tumors. Interestingly, STAT3 and NRF2 can also interact with each other to regulate tumor progression. Hence, these two important transcription factors are considered key targets for developing a new class of antitumor drugs. This review summarizes the pivotal roles of the two transcription regulators and their interactions in the tumor microenvironment to identify potential antitumor drug targets and, ultimately, improve patients' health and survival.

MicroRNA-140-5p inhibits cellular proliferation, migration and invasion by downregulating AKT/STAT3/NF-κB pathway in breast carcinoma cells

MicroRNA-140-5p (miR-140-5p) plays a pivotal role in human cancers. However, its role and molecular mechanisms in breast carcinoma are not fully explored. Using miR-140-5p transfected breast cancer cell line MDA-MB-231, several in vitro experiments were performed and described in this paper. They consist of the cell proliferation assay, wound healing assay, transwell assay, colony formation assays and qRTPCR. Expression levels of target proteins were determined using Western blotting. In addition, experiments on animal models were performed to study the possible role of miR-140-5p in tumorigenesis of breast carcinoma cells. The induction of experimental breast tumor in mice model was achieved through the incorporation of MDA-MB-231 tumor cells subcutaneously into the middle left side of the mice. The results showed that miR-140-5p up-regulation significantly suppresses proliferation, cellular invasion and migration of breast carcinoma cells. Furthermore, miR-140-5p up-regulation stops breast cancer cells at G0/G1 phase. The results of the animal model indicated that up-regulation of miR-140-5p suppresses its tumorigenic ability. Moreover, we also found that miR-140-5p up-regulation reduces the phosphorylation level of STAT3, p65, and AKT. In addition, miR-140-5p overexpression significantly decreases CDK2 expression while increasing E-cadherin expression level. These data revealed that miR-140-5p suppressed tumor progression of breast carcinoma cells through inhibition of the AKT/STAT3/NF-κB pathway. Taken the present study results together, we can conclude that miR-140-5p may act as a novel target in microRNA-targeting anticancer strategy for the treatment of breast cancer.

Emerging role of IκBζ in inflammation: Emphasis on psoriasis

Psoriasis is a chronic inflammatory disorder affecting skin and joints that results from immunological dysfunction such as enhanced IL-23 induced Th-17 differentiation. IkappaB-Zeta (IκBζ) is an atypical transcriptional factor of the IκB protein family since, contrary to the other family members, it positively regulates NF-κB pathway by being exclusively localized into the nucleus. IκBζ deficiency reduces visible manifestations of experimental psoriasis by diminishing expression of psoriasis-associated genes. It is thus tempting to consider IκBζ as a potential therapeutic target for psoriasis as well as for other IL23/IL17-mediated inflammatory diseases. In this review, we will discuss the regulation of expression of NFKBIZ and its protein IκBζ, its downstream targets, its involvement in pathogenesis of multiple disorders with emphasis on psoriasis and evidences supporting that inhibition of IκBζ may be a promising alternative to current therapeutic managements of psoriasis.

Palbociclib Induces the Apoptosis of Lung Squamous Cell Carcinoma Cells via RB-Independent STAT3 Phosphorylation

Lung squamous cell carcinoma (LUSC) treatment response is poor and treatment alternatives are limited. Palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, has recently been approved for hormone receptor-positive breast cancer patients and applied in multiple preclinical models, but its use for LUSC therapy remains elusive. Here, we investigated whether palbociclib induced cell apoptosis and dissected the underlying mechanism in LUSC. We found that palbociclib induced LUSC cell apoptosis through inhibition of Src tyrosine kinase/signal transducers and activators of transcription 3 (STAT3). Interestingly, palbociclib reduced STAT3 signaling in LUSC cells interfered by retinoblastoma tumor-suppressor gene (RB), suggesting that pro-apoptosis effect of palbociclib was independent of classic CDK4/6-RB signaling. Furthermore, palbociclib could suppress IL-1β and IL-6 expression, and therefore blocked Src/STAT3 signaling, which were rescued by either recombinant human IL-1β or IL-6. Moreover, Myc mediated the sensitivity of LUSC cells to palbociclib. Our discoveries demonstrated that palbociclib induces apoptosis of LUSC cells through the Src/STAT3 axis in an RB-independent manner, and provided a reliable experimental basis of clinical studies in LUSC patients.

The multifaceted role of STAT3 pathway and its implication as a potential therapeutic target in oral cancer

Oral cancer is one of the leading causes of cancer-related deaths, and it has become a matter of serious concern due to the alarming rise in its incidence rate worldwide. Despite recent advancements in oral cancer treatment strategies, there are no significant improvements in patient's survival rate. Among the numerous cell signaling pathways involved in oral cancer development and progression, STAT3 is known to play a multifaceted oncogenic role in shaping the tumor pathophysiology. STAT3 hyperactivation in oral cancer contributes to survival, proliferation, invasion, epithelial to mesenchymal transition, metastasis, immunosuppression, chemoresistance, and poor prognosis. A plethora of pre-clinical and clinical studies have documented the role of STAT3 in the initiation and development of oral cancer and showed that STAT3 inhibition holds significant potential in the prevention and treatment of this cancer. However, to date, targeting STAT3 activation mainly involves inhibiting the upstream signaling molecules such as JAK and IL-6 receptors. The major challenge in targeting STAT3 lies in the complexity of its phosphorylation- and dimerization-independent functions, which are not affected by disrupting the upstream regulators. The present review delineates the significance of the STAT3 pathway in regulating various hallmarks of oral cancer. In addition, it highlights the STAT3 inhibitors identified to date through various preclinical and clinical studies that can be employed for the therapeutic intervention in oral cancer treatment.

N4BP3 promotes angiogenesis in Hepatocellular Carcinoma by binding with KAT2B

Although angiogenesis is a critical event in hepatocellular carcinoma (HCC), and this process provides the tumor with sufficient oxygen and nutrients, the precise molecular mechanism by which it occurs is not fully understood. NEDD4 binding protein 3 (N4BP3) was identified in this study as a novel pro‐angiogenic factor in HCC cell lines and tissues. We discovered that N4BP3 was significantly expressed in HCC and that its level of expression was positively correlated with the density of tumor microvessels in HCC tissues. Cell biology experiments have shown that N4BP3 knockdown in HCC cells significantly inhibits the formation of complete tubular structures by HUVECs in vitro and HCC angiogenesis in vivo. In HCC cells, overexpression of N4BP3 has the opposite effects. Further cell and molecular biology experiments have revealed that N4BP3 interacts with KAT2B (lysine acetyltransferase 2B), increasing signal transducer and activator of transcription 3 (STAT3) expression by regulating the distribution of acetyl‐histone H3 (Lys27) (H3K27ac) in its promoter region. This, in addition, regulates the activity of the STAT3 signaling pathway, which promotes the proliferation of microvessels in HCC and accelerates the malignant process of the tumor. In vivo experiments in nude mice have confirmed our findings, and also suggested that N4BP3 could be a potential target for the treatment of HCC in combination with sorafenib.

Oxyresveratrol Reduces the Migration of Human Osteosarcoma Cell U2OS via Attenuating STAT3 Activation

Objective: Osteosarcoma is a malignant tumor with high metastatic properties that are associated with increased mortality and poor prognosis. Therefore, it is crucial to develop an effective treatment for metastatic osteosarcoma. Oxyresveratrol (ORES), derived from mulberry twigs and fruits, has antitumor effects. However, it remains unknown whether ORES inhibits osteosarcoma metastasis. In this study, we determined the inhibitory effect of ORES on osteosarcoma metastasis. Key Findings: ORES attenuated the migration of U2OS cells, dose-dependently increased E-cadherin expression, and reduced N-cadherin expression in U2OS cells, indicating that ORES can inhibit epithelial–mesenchymal transition (EMT) in osteosarcoma cells. Furthermore, ORES inhibited the expression of Twist, which is associated with the downregulation of STAT3 phosphorylation. IL-6-induced STAT3 phosphorylation rescues the inhibitory effect of ORES on U2OS metastasis. Summary: Our results indicate that ORES is a potential therapeutic agent for metastatic osteosarcoma. ORES inhibits osteosarcoma cell migration by reducing EMT formation.

Genipin, an Inhibitor of UCP2 as a Promising New Anticancer Agent: A Review of the Literature

Genipin is a protein cross-linking agent extracted from Gardenia (Gardenia jasminoides Ellis) fruits. This fruit has conventionally been used as a Chinese herbal medicine for the treatment of inflammation and jaundice and as an edible colorant in oriental countries. Uncoupling protein (UCP)-2 is a member of the family of uncoupling proteins, which are anion transporters positioned in the mitochondrial inner membrane. Genipin has been shown to have hepatoprotective activity, acting as an effective antioxidant and inhibitor of mitochondrial UCP2, and is also reported to exert significant anticancer effects. In this review, the author presents the latest progress of genipin as an anticancer agent and concisely describes its various mechanisms of action. In brief, genipin inhibits UCP2 to attenuate generation of reactive oxygen species (ROS), leading to ROS/c-Jun N-terminal kinase-dependent apoptosis of cancer cells. Genipin also increases the tissue inhibitors of matrix metalloproteases (MMP)-2, a kind of tumor promoter in a variety of cancers, as well as induces caspase-dependent apoptosis in in vitro and in vivo models. These findings suggest that genipin can serve as a promising novel antitumor agent that could be applicable for chemotherapy and/or chemoprevention for cancers.

Telocinobufagin Has Antitumor Effects in Non-Small-Cell Lung Cancer by Inhibiting STAT3 Signaling

Non-small-cell lung carcer (NSCLC), the main histological subtype of lung cancer, is responsible for significant morbidity and mortality worldwide. Telocinobufagin, an active compound of the Chinese traditional medicine ChanSu, has antitumor effects, but its mechanism of action remains unknown. Therefore, we investigated the effect of telocinobufagin on NSCLC growth and metastasis and its possible mechanism of action, in vitro and in vivo. Cell proliferation, migration, and apoptosis were measured by methyl thiazol tetrazolium assay, colony formation, 5-ethynyl-2'-deoxyuridine incorporation, Transwell migration, wound healing, and flow cytometry analysis. A mouse xenograft model was used to evaluate tumor formation in vivo. Telocinobufagin was found to suppress proliferation and metastasis and induce apoptosis in human NSCLC cells. Moreover, telocinobufagin was able to significantly inhibit STAT3 phosphorylation at tyrosine 705 (Y⁷⁰⁵) and its downstream targets. Additionally, telocinobufagin also impaired the IL-6-induced nuclear translocation of STAT3. Consistent with the in vitro experiments, telocinobufagin reduced the A549 xenograft tumor burden and the levels of P-STAT3^Y705, MCL1, BCL2, and cleaved PARP1 in vivo. These results support telocinobufagin as a promising STAT3 signaling inhibitor candidate for the treatment of NSCLC patients.

Targeting regulated cell death (RCD) with small-molecule compounds in triple-negative breast cancer: a revisited perspective from molecular mechanisms to targeted therapies

Triple-negative breast cancer (TNBC) is a subtype of human breast cancer with one of the worst prognoses, with no targeted therapeutic strategies currently available. Regulated cell death (RCD), also known as programmed cell death (PCD), has been widely reported to have numerous links to the progression and therapy of many types of human cancer. Of note, RCD can be divided into numerous different subroutines, including autophagy-dependent cell death, apoptosis, mitotic catastrophe, necroptosis, ferroptosis, pyroptosis and anoikis. More recently, targeting the subroutines of RCD with small-molecule compounds has been emerging as a promising therapeutic strategy, which has rapidly progressed in the treatment of TNBC. Therefore, in this review, we focus on summarizing the molecular mechanisms of the above-mentioned seven major RCD subroutines related to TNBC and the latest progress of small-molecule compounds targeting different RCD subroutines. Moreover, we further discuss the combined strategies of one drug (e.g., narciclasine) or more drugs (e.g., torin-1 combined with chloroquine) to achieve the therapeutic potential on TNBC by regulating RCD subroutines. More importantly, we demonstrate several small-molecule compounds (e.g., ONC201 and NCT03733119) by targeting the subroutines of RCD in TNBC clinical trials. Taken together, these findings will provide a clue on illuminating more actionable low-hanging-fruit druggable targets and candidate small-molecule drugs for potential RCD-related TNBC therapies.

JAK/STAT Signaling: Molecular Targets, Therapeutic Opportunities, and Limitations of Targeted Inhibitions in Solid Malignancies

JAK/STAT signaling pathway is one of the important regulatory signaling cascades for the myriad of cellular processes initiated by various types of ligands such as growth factors, hormones, and cytokines. The physiological processes regulated by JAK/STAT signaling are immune regulation, cell proliferation, cell survival, apoptosis and hematopoiesis of myeloid and non-myeloid cells. Dysregulation of JAK/STAT signaling is reported in various immunological disorders, hematological and other solid malignancies through various oncogenic activation mutations in receptors, downstream mediators, and associated transcriptional factors such as STATs. STATs typically have a dual role when explored in the context of cancer. While several members of the STAT family are involved in malignancies, however, a few members which include STAT3 and STAT5 are linked to tumor initiation and progression. Other STAT members such as STAT1 and STAT2 are pivotal for antitumor defense and maintenance of an effective and long-term immune response through evolutionarily conserved programs. The effects of JAK/STAT signaling and the persistent activation of STATs in tumor cell survival; proliferation and invasion have made the JAK/STAT pathway an ideal target for drug development and cancer therapy. Therefore, understanding the intricate JAK/STAT signaling in the pathogenesis of solid malignancies needs extensive research. A better understanding of the functionally redundant roles of JAKs and STATs may provide a rationale for improving existing cancer therapies which have deleterious effects on normal cells and to identifying novel targets for therapeutic intervention in solid malignancies.

LINC00982 Inhibits the Proliferation, Migration, and Invasion of Breast Cancer Cells Through the miR-765/DPF3 Axis

Breast cancer (BC) is one of the most frequently occurring malignant tumors in female adults. The long intergenic nonprotein coding RNA 00982 (LINC00982) has been regarded as a cancer suppressor in several human cancers. However, the function and the underlying mechanisms of LINC00982 have not been studied in BC. The present study found that LINC00982 was significantly downregulated in BC tumor tissues, and the low LINC00982 level predicts a poor prognosis of BC. Through the overexpression and suppression of LINC00982 in two BC cell lines, we found that LINC00982 could inhibit cell proliferation, migration, and invasion by suppressing the activity of the signal transducer and activator of transcription 3 (STAT3)/nuclear factor kappa B (NF-κB) signal pathway. Furthermore, luciferase reporter assay has been used to verify that LINC00982 functions as a molecular sponge for miR-765, which could target DPF3. The relative expression of miR-765 decreased with LINC00982 overexpressing, and DPF3 increased at the same time. In addition, the suppression of cell malignant phenotype caused by overexpression of LINC00982 can be reversed by inhibition of DPF3. To verify the function of LINC00982 in vivo, the BC cells were implanted in nude mice and the results suggested the tumor growth and malignant phenotype were suppressed by LINC00982. In this study, we prove that LINC00982 regulates the growth and development of BC through STAT3/NF-κB signal pathway, mediated by the miR-765/DPF3 axis. LINC00982 may function as a target molecule to take part in the prognosis and therapy of BC.

The critical role of STAT3 in biogenesis of tumor-derived exosomes with potency of inducing cancer cachexia in vitro and in vivo

Tumor-derived exosomes are emerging mediators of cancer cachexia. Clarifying the regulation of exosome biogenesis and finding possible targets for cancer cachexia therapy are important and necessary. In the present study, systemic analysis of the roles of STAT3 in controlling exosome biogenesis of murine C26 colon tumor cells and its contribution to the development of cancer cachexia is conducted. The genetic manipulation of STAT3 expression, STAT3 knockout (KO) or overexpression (OE), significantly affected the exosome biogenesis and also the potency of C26 conditioned medium (CM) in inducing muscle atrophy and lipolysis in vitro. The genetic manipulation of STAT3 expression caused change in phosphorylation of PKM2 and glycolysis. PKM2/SNAP23 pathway was involved in regulation of exosome biogenesis by STAT3 genetic manipulation as well as by STAT3 inhibitors in C26 cells. Mice inoculated with STAT3 knockout or overexpression C26 cells exhibited ameliorated or aggravated cancer cachexia symptoms, with a positive correlation with the serum exosome and IL-6 levels. The STAT3/PKM2/SNAP23 pathway was affected in C26 tumor tissues with genetic manipulation of STAT3 expression. The capacity of exosome biogenesis of different human cancer cells also exhibited a positive correlation with the activation of STAT3/PKM2/SNAP23 pathway. The research presented here confirms that STAT3 plays a critical role in regulating biogenesis of tumor-derived exosomes which could contribute to cancer cachexia development.

Targets and Strategies for Cancer Immunoprevention

The immune system plays a key role in cancer prevention, initiation, and progression. Antitumoral immune responses can be boosted by harnessing antitumorigenic immune activators and/or blocking tumorigenic proinflammatory factors. Here we define these targets as well as the strategies that could be developed for effective cancer immunoprevention.

Interleukin-9 attenuates inflammatory response and hepatocyte apoptosis in alcoholic liver injury

Alcoholic liver injury is a liver cell dysfunction disease caused by long-term or excessive alcohol consumption. Inhibiting the production of inflammatory factors is an important way to alleviate liver injury. Interleukin-9 (IL-9) is one of the members of IL-2Rγc family. It has multiple biological functions. Previous studies have shown that IL-9 is a cytokine that is closely related to inflammatory disease, allergic diseases, autoimmune diseases, and parasitic infections. However, no systematic studies have been performed to address the role of IL-9 in ALI. This project aims to investigate the effects of IL-9 on macrophage-related inflammatory response and hepatocyte apoptosis in alcohol-induced liver injury by injecting adeno-associated virus (AAV9) into tail vein. In the ALI model group, western blot and ELISA assays demonstrated that the expression of IL-9 was reduced. Overexpression of IL-9 relieved the injury and reduced the serum levels of IL-6, TNF-α in EtOH-induced ALI mouse model. Moreover, by using western blot, it was indicated that IL-9 can inhibit the expression of pro-apoptotic protein, such as cleaved caspase 3 and Bax. In vitro, mouse recombinant protein IL-9 inhibited the expression of IL-6, TNF-α in EtOH-induced RAW264.7 cells. Moreover, flow cytometry and western blot results displayed that macrophage-derived IL-9 inhibited hepatocyte apoptosis. After silencing STAT3 in AML-12 cells, the anti-apoptotic effect of macrophage-derived IL-9 was further enhanced. These results indicate that IL-9 reduces the production of pro-inflammatory factors in ALI. Furthermore, macrophage-derived IL-9 can reduce hepatocyte apoptosis by inhibiting the activation of the STAT3 pathway.

Decursin inhibits tumor progression in head and neck squamous cell carcinoma by downregulating CXCR7 expression in vitro

CXC chemokine receptor 7 (CXCR7) is frequently overexpressed in cancer and plays a significant role in tumor growth and metastasis. Consequently, inhibition of CXCR7 is important for treatment strategies. However, little is known concerning the biological role of CXCR7 and its underlying mechanisms in head and neck squamous cell carcinoma (HNSCC). The present study investigated the role of CXCR7 in HNSCC, as well as the effects of decursin, a pyranocoumarin compound isolated from Angelica gigas Nakai, on CXCR7 and its downstream signaling. Expression levels of CXCR7 in HNSCC cells were examined using flow cytometry, reverse transcriptase PCR, western blot analysis, and immunofluorescence. The effects of CXCR7 on cell proliferation, migration, and invasion were studied using CCK-8, gap closure, and transwell assays. The results revealed that decursin significantly reduced CXCR7 expression and inhibited cell proliferation, migration, and invasion of human HNSCC cell lines. In addition, decursin induced G0/G1 cell cycle arrest in CXCR7-overexpressing cells and decreased the levels of cyclin A, cyclin E, and CDK2. Furthermore, CXCR7 promoted cancer progression via the STAT3/c-Myc pathway in HNSCC; suppression of CXCR7 with decursin prevented this effect. These results suggest that CXCR7 promotes cancer progression through the STAT3/c-Myc pathway and that the natural compound decursin targets CXCR7 and may be valuable in the treatment of HNSCC.

Identification of Key Transcription Factors and Immune Infiltration Patterns Associated With Breast Cancer Prognosis Using WGCNA and Cox Regression Analysis

Breast cancer is the most frequently diagnosed cancer and the second leading cause of cancer death among women worldwide. Therefore, the need for effective breast cancer treatment is urgent. Transcription factors (TFs) directly participate in gene transcription, and their dysregulation plays a key role in breast cancer. Our study identified 459 differentially expressed TFs between tumor and normal samples from The Cancer Genome Atlas database. Based on gene expression analysis and weighted gene co-expression network analysis, the co-expression yellow module was found to be integral for breast cancer progression. A total of 121 genes in the yellow module were used for function enrichment. To further confirm prognosis-related TFs, COX regression and LASSO analyses were performed; consequently, a prognostic risk model was constructed, and its validity was verified. Ten prognosis-related TFs were identified according to their expression profile, survival probability, and target genes. COPS5, HDAC2, and NONO were recognized as hub TFs in breast cancer. These TFs were highly expressed in human breast cancer cell lines and clinical breast cancer samples; this result was consistent with the information from multiple databases. Immune infiltration analysis revealed that the proportions of resting dendritic and mast cells were greater in the low-risk group than those in the high-risk group. Thus, in this study, we identified three hub biomarkers related to breast cancer prognosis. The results provide a framework for the co-expression of TF modules and immune infiltration in breast cancer.

Abrogation of STAT3 activation cascade by Ginkgolide C mitigates tumourigenesis in lung cancer preclinical model

OBJECTIVES

Ginkgolide C (GGC) isolated from Ginkgo biloba (Ginkgoaceae) leaf can demonstrate pleiotropic pharmacological actions. However, its anti-oncogenic impact in non-small cell lung cancer (NSCLC) model has not been reconnoitered. As signal transducer and activator of transcription 3 (STAT3) cascade can promote tumour growth and survival, we contemplated that GGC may interrupt this signalling cascade to expend its anti-cancer actions in NSCLC.

METHODS

The effect of GGC on STAT3 activation, associated protein kinases, STAT3-regulated gene products, cellular proliferation and apoptosis was examined. The in-vivo effect of GGC on the growth of human NSCLC xenograft tumours in athymic nu/nu female mice was also investigated.

KEY FINDINGS

GGC attenuated the phosphorylation of STAT3 and STAT3 upstream kinases effectively. Exposure to pervanadate modulated GGC-induced down-regulation of STAT3 activation and promoted an elevation in the level of PTPε protein. Indeed, silencing of the PTPε gene reversed the GGC-promoted abrogation of STAT3 activation and apoptosis. Moreover, GGC exposure significantly reduced NSCLC tumour growth without demonstrating significant adverse effects via decreasing levels of p-STAT3 in mice tissues.

CONCLUSIONS

Overall, the findings support that GGC may exhibit anti-neoplastic actions by mitigation of STAT3 signalling cascade in NSCLC.

Study of transcription factor druggabilty for prostate cancer using structure information, gene regulatory networks and protein moonlighting

Prostate cancer is the second leading cause of cancer-related death in men. Metastasis shows poor survival even though the recovery rate is high. In spite of numerous studies regarding prostate carcinoma, multiple questions are still unanswered. In this regards, gene regulatory network can uncover the mechanisms behind cancer progression, and metastasis. Under a feed forward loop, transcription factors (TFs) can be a good druggable candidate. We have proposed a computational model to study the uncertainty of TFs and suggest the appropriate cellular conditions for drug targeting. We have selected feed-forward loops depending on the shared list of the functional annotations among TFs, genes and miRNAs. From the potential feed forward loop cores, six TFs were identified as druggable targets, which include AR, CEBPB, CREB1, ETS1, NFKB1 and RELA. However, TFs are known for their Protein Moonlighting properties, which provide unrelated multi-functionalities within the same or different subcellular localizations. Following that, we have identified such functions that are suitable for drug targeting. On the other hand, we have tried to identify membraneless organelles for providing more specificity to the proposed time and space theory. The study has provided certain possibilities on TF-based therapeutics. The controlled dynamic nature of the TF may have enhanced the chances where TFs can be considered as one of the prime drug targets. Finally, the combination of membranless phase separation and protein moonlighting has provided possible druggable period within the biological clock.

Pharmacologic inhibiting STAT3 delays the progression of kidney fibrosis in hyperuricemia-induced chronic kidney disease

AIMS

Kidney fibrosis is a histological hallmark of chronic kidney disease (CKD), where hyperuricemia is a key independent risk factor. Considerable evidence indicated that STAT3 is one of the crucial signaling pathways in the progression of kidney fibrosis. Here, we investigated that pharmacological blockade of STAT3 delayed the progression of renal fibrosis in hyperuricemia-induced CKD.

MAIN METHODS

In the study, we used the mixture of adenine and potassium oxonate to perform kidney injury and fibrosis in hyperuricemic mice, accompanied by STAT3 activation in tubular and interstitial cells.

KEY FINDINGS

Treatment with STAT3 inhibitor S3I-201 improved renal dysfunction, reduced serum uric acid level, and delayed the progression of kidney fibrosis. Furthermore, S3I-201 could suppress fibrotic signaling pathway of TGF-β/Smads, JAK/STAT and NF-κB, as well as inhibit the expression of multiple profibrogenic cytokines/chemokines in the kidneys of hyperuricemic mice.

SIGNIFICANCE

These data suggested that STAT3 inhibition was a potent anti-fibrotic strategy in hyperuricemia-related CKD.