STAT3 inhibition, a novel approach to enhancing targeted therapy in human cancers (review)

Banxia Xiexin Decoction inhibits colitis-associated colorectal cancer development by modulating STAT3 signaling and gut microbiota

Objective

To investigate the therapeutic effects of Banxia Xiexin Decoction (BXD), a herbal medicine formula, on inflammation and the imbalance of the gut microbiota in a rat model of colorectal cancer (CRC) induced by azoxymethane (AOM) /dextran sulfate sodium (DSS).

Methods

A total of 75 male C57BL/6 mice were randomly divided into five groups: normal control group (NC), model group (MODEL), low-dose BXD treatment group (L-BXD), high-dose BXD treatment (H-BXD) group and MS treatment group (MS). BXD and MS were used in CRC mice at the doses of 3.915 g/kg, 15.66 g/kg, 0.6 g/kg for 3 weeks consecutively. Histopathological changes in the colon were observed using hematoxylin-eosin (HE) staining. The content of inflammatory factors in serum was detected by an enzyme-linked immunosorbent assay (ELISA), and the expression of mRNA and protein of genes related to immunity, apoptosis, inflammation, and inflammatory factors was evaluated. Changes in the intestinal flora of mouse fecal were determined based on high-throughput sequencing of the 16S rRNA microbial gene.

Results

Compared to the model group, the low-dose BXD and high-dose BXD groups decreased the number of colon tumors, reversed weight loss, and shortened colon length of mice. The pathological examination showed that BXD alleviated the malignancy of intestinal tumors. It also suppressed signal transducer and activator of transcription 3 (STAT3), matrix metalloproteinase-9 (MMP-9), and transforming growth factor beta 1 (TGF-β1) expression, while increasing the expression of the tight junction protein ZO-1 in colon tissues. Additionally, the levels of key pathway proteins involved in inflammation (phosphorylated-STAT3, Bcl-2, COX-2) and cell cycle regulatory molecules (c-Myc and PCNA) were reduced. According to 16S rRNA sequence analysis, BXD enhanced the relative abundance of potentially beneficial bacteria, while that of cancer-related bacteria decreased.

Conclusion

BXD plays a preventive role in developing colorectal cancer; its mechanisms are related to the inhibition of inflammation and tumor proliferation, as well as maintenance of intestinal homeostasis.

Evaluating the specific STAT3 inhibitor YHO-1701 in ovarian cancer cell lines and patient-derived cell models: efficacy, mechanisms, and therapeutic potential

OBJECTIVE

Signal transducer and activator of transcription 3 (STAT3) plays key roles in regulating cancer cell proliferation, survival, and metastasis. We aimed to determine the effects of YHO-1701, an oral STAT3 inhibitor, in ovarian cancer (OC).

METHODS

We evaluated the impact of YHO-1701 on cell growth in patient-derived cells (PDCs) and OC cell lines using standard cell proliferation assays. Spheroid models derived from PDCs were assessed using three-dimensional (3D) cell viability assays. Antitumor activity was performed in SKOV3 xenograft mice treated orally administrated YHO-1701 with 20 mg/kg. Changes in STAT3 signaling were analyzed by western blotting. The molecular mechanisms of STAT3 inhibition were investigated by sequencing RNA and analyzing pathways in the SKOV3 using a small interfering RNA targeting STAT3 (STAT3 siRNA) and YHO-1701.

RESULTS

YHO-1701 inhibited the growth of OC cell lines by preventing STAT3 dimerization and decreasing the expression of its downstream signaling molecule, survivin. The growth of PDCs and spheroids obtained from patients with primary and recurrent OCs was significantly inhibited. Antitumor effect was observed in the SKOV3 xenograft mice with YHO-1701. YHO-1701 induced apoptosis in OC cells. Additionally, p53 and/or MAPK signaling pathways were upregulated in SKOV3 cells incubated with YHO-1701 and in those with STAT3 siRNA.

CONCLUSION

Our results showed that YHO-1701 suppressed cell growth in PDCs of OC, accompanied by survivin inhibition, and a decrease in the number of peritoneal metastasis in the mice by YHO-1701, compared with those treated with control. Therefore, YHO-1701 could be a promising candidate agent for treating OC.

pSTAT3 Expression is Increased in Advanced Prostate Cancer in Post-Initiation of Androgen Deprivation Therapy

BACKGROUND

The transcription factor Signal Transducer and Activator of Transcription 3 (STAT3) plays a role in carcinogenesis and is involved in processes, such as proliferation, differentiation, drug resistance and immunosuppression. STAT3 can be activated by phosphorylation of tyrosine at position 705 (pSTAT3Tyr705) or serine at 727 (pSTAT3Ser727). High expression levels of pSTAT3 are implicated in advanced stages of prostate cancer (PCa) and are known to interact with the androgen receptor signaling pathway. However, not much is known about how androgen deprivation therapy (ADT) in advanced disease affects pSTAT3 expression. The aim of this study was to determine the influence of ADT on pSTAT3 expression in PCa tissue.

METHODS

The study cohort came from a PCa tissue microarray resource containing prostate specimens from patients before and post-initiation of ADT. Tissue samples from 111 patients were immunostained for pSTAT3Tyr705 and pSTAT3Ser727. H-score was used to evaluate the intensity and the percentage of pSTAT3 expression in malignant epithelial and stromal compartments. Univariate and multivariable Cox regression analyses were used to assess pSTAT3Tyr705 and pSTAT3Ser727 as biomarkers of oncological outcome in patients undergoing ADT.

RESULTS

Post-ADT PCa samples demonstrated increased nuclear and cytoplasmic levels of pSTAT3Ser727 in the stroma compared to pre-ADT samples, whereas pSTAT3Tyr705 expression was increased significantly in both stromal and malignant epithelial compartments except for stromal cytoplasm. High cytoplasmic pSTAT3Ser727 in stromal compartments correlated with reduced overall survival, shorter time to castration-resistant PCa development, and decreased metastasis-free survival. An increase in nuclear and cytoplasmic pSTAT3Ser727 expression within the stromal compartment of post-ADT samples corresponded to a shorter time to CRPC development, which was not observed for pSTAT3Tyr705. Multivariable survival analysis using Cox's regression identified that high cytoplasmic pSTAT3Ser727 expression in the stroma of post-ADT samples and pT3 or pT4-stage were associated with worse overall survival and 5-year metastasis-free survival (MFS).

CONCLUSIONS

This study presents novel insights into the impact of ADT on the expression levels of pSTAT3Tyr705 and pSTAT3Ser727 in PCa. Cytoplasmic pSTAT3Ser727 status of cancer-associated stromal cells in post-ADT samples may serve as an independent prognostic marker for OS and 5-year MFS, identifying prostate cancer patients prone to developing resistance to ADT.

A strategic review of STAT3 signaling inhibition by phytochemicals for cancer prevention and treatment: Advances and insights

Cancer remains a significant global health concern. The dysregulation of signaling networks in tumor cells greatly affects their functions. This review intends to explore phytochemicals possessing potent anticancer properties that specifically target the STAT3 signaling pathway, elucidating strategies and emphasizing their potential as promising candidates for cancer therapy. The review comprehensively examines various STAT3 inhibitors designed to disrupt the signaling cascade, including those targeting upstream activation, SH2 domain phosphorylation, DNA binding domain (DBD), N-terminal domain (NTD), nuclear translocation, and enhancing endogenous STAT3 negative regulators. A literature review was conducted to identify phytochemicals with anticancer activity targeting the STAT3 signaling pathway. Popular research databases such as Google Scholar, PubMed, Science Direct, Scopus, Web of Science, and ResearchGate were searched from the years 1989 - 2023 based on the keywords "Cancer", "STAT3", "Phytochemicals", "Phytochemicals targeting STAT3 signaling", "upstream activation of STAT3", "SH2 domain of STAT3", "DBD of STAT3", "NTD of STAT3, "endogenous negative regulators of STAT3", or "nuclear translocation of STAT3", and their combinations. A total of 264 relevant studies were selected and analyzed based on the mechanisms of action and the efficacy of the phytocompounds. The majority of the discussed phytochemicals primarily focus on inhibiting upstream activation of STAT3. Additionally, flavonoid and terpenoid compounds exhibit multifaceted effects by targeting one or more checkpoints within the STAT3 pathway. Analysis reveals that phytochemicals targeting upstream activation predominantly belong to the classes of flavonoids and terpenoids, which hold significant promise as effective anticancer therapeutics. Future research in this field can be directed towards exploring and developing these scrutinized classes of phytochemicals to achieve desired therapeutic outcomes in cancer treatment.

In-silico assessment of novel peptidomimetics inhibitor targeting STAT3 and STAT4 N-terminal domain dimerization: A comprehensive study using molecular docking, molecular dynamics simulation, and binding free energy analysis

Dysregulation in Janus kinase-Signal Transducer and Activation of Transcription (JAK-STAT) pathway is closely linked to various cancer types. The N-terminal domain (NTD) of STAT proteins, upon dimerization, assumes a multifaceted role with remarkable adaptability in mediating interactions between proteins. Consequently, the strategic targeting of the N-terminal domain of STATs has emerged as a promising tactic for disrupting dimerization and impeding the translocation of STAT proteins. In this study, we have deployed an integrated in-silico methodology to rationally design Peptidomimetic foldamers as inhibitors of the N-terminal domains of STAT3 and STAT4, with the objective of disrupting protein dimerization. Consequently, we have judiciously designed a series of peptidomimetics that encompass β3-amino acids, bearing side chains that mimic the residues within interface II of the dimeric structures of the NTDs. Employing molecular docking techniques; we have assessed the binding affinity of these designed peptidomimetics toward both the NTDs. Furthermore, we have conducted an evaluation of the stability and conformational alterations within the docked complexes over an extensive Molecular Dynamics, subsequently computing the binding free energy utilizing MM/PBSA calculations. Our findings unequivocally demonstrate that the peptidomimetic foldamers we have devised (Peptide-A, Peptide-B, and Peptide-C) exhibit a propensity to bind to and impede the dimerization process of the NTDs of both STAT3 and STAT4. These outcomes serve to underscore the potential of these meticulously designed peptidomimetics as potential candidates meriting further exploration in the realm of cancer prevention and management.

Effect of Soy Isoflavone on Prostate Cancer Cell Apoptosis Through Inhibition of STAT3, ERK, and AKT

Genistein, an isoflavone found in soybeans, exhibits antioxidant, anti-inflammatory, and anticancer properties. This study explored the molecular mechanisms behind genistein's anticancer effects in prostate cancer DU145 cells. In this study, genistein decreased cell viability, increased annexin V-PE(+) cells, and enhanced the sub-G0/G1 peak by flow cytometric analysis. Increased reactive oxygen species increased mitochondrial depolarization indicating mitochondrial dysfunction and inhibition of ATP formation were also observed in genistein-treated DU145 cells. Genistein upregulated p53 at the mRNA and protein levels and increased caspase-3/7 activity along with the cleavage of Bax, procaspase-3, and PARP. With the increasing genistein concentrations, the percentage of cells in the sub-G0/G1 peak and G2/M phase increased, which was inhibited by treatment with the pan-caspase inhibitor Z-VAD together with 100 μM genistein, which had little toxicity to normal prostate epithelial HPrEC cells. Genistein treatment simultaneously inhibited the activation of STAT3 and other closely related oncogenic kinases such as AKT and ERK and p38 and decreased VEGF expression. Taken together, these results suggest that genistein inhibits the growth of DU145 cells and induces apoptosis by inhibiting STAT3, AKT, ERK, and p38 which provides a molecular basis for the anticancer activity of genistein and suggests its potential as a valuable therapeutic candidate for prostate cancer.

STAG2 promotes naive-primed transition via activating Lin28a transcription in mouse embryonic stem cells

Mouse embryonic stem cells (mESCs) exist in two distinct pluripotent states: the naive and the primed. Mainly by inducing differentiation of mESCs in vitro, conducting RNA sequencing analyses, and specifying expression of the regulatory genes, we explored the regulatory mechanisms underlying the transition between the naive and primed states. We found that, under the defined differentiation-inducing conditions, the naive state of mESCs shifted to the primed state within 2 days of differentiation induction, during which the cell cycle- and differentiation-related proteins changes significantly. Specifically, we uncovered that the expression of STAG2, a subunit of the Cohesin complex, was upregulated. We further revealed that knockout of STAG2 resulted in upregulation of the naive gene sets and downregulation of the primed gene sets, indicating importance of STAG2 in regulating the naive-primed transition. More importantly, STAG2 knockout led to a reduction in number of the bivalent genes, a decrease in Lin28a transcription, and a reduced cytoplasmic localization of Lin28a. Overexpressing Lin28a or a Lin28a variant lacking the nucleolar localization signal (Lin28aΔNoLS) in STAG2 knockout cells rescued the downregulation of the primed marker genes Dnmt3a/3b. Collectively, we conclude that STAG2 facilitates the naive-primed transition of mESCs by activating Lin28a transcription and that this work may offer a new insight into the regulation of pluripotency in mESCs.

Inhibition of STAT3: A promising approach to enhancing the efficacy of chemotherapy in medulloblastoma

Medulloblastoma is a type of brain cancer that primarily affects children. While chemotherapy has been shown to be effective in treating medulloblastoma, the development of chemotherapy resistance remains a challenge. One potential therapeutic approach is to selectively inhibit the inducible transcription factor called STAT3, which is known to play a crucial role in the survival and growth of tumor cells. The activation of STAT3 has been linked to the growth and progression of various cancers, including medulloblastoma. Inhibition of STAT3 has been shown to sensitize medulloblastoma cells to chemotherapy, leading to improved treatment outcomes. Different approaches to STAT3 inhibition have been developed, including small-molecule inhibitors and RNA interference. Preclinical studies have shown the efficacy of STAT3 inhibitors in medulloblastoma, and clinical trials are currently ongoing to evaluate their safety and effectiveness in patients with various solid tumors, including medulloblastoma. In addition, researchers are also exploring ways to optimize the use of STAT3 inhibitors in combination with chemotherapy and identify biomarkers that can predict treatment that will help to develop personalized treatment strategies. This review highlights the potential of selective inhibition of STAT3 as a novel approach for the treatment of medulloblastoma and suggests that further research into the development of STAT3 inhibitors could lead to improved outcomes for patients with aggressive cancer.

Research progress of multi-target HDAC inhibitors blocking the BRD4-LIFR-JAK1-STAT3 signaling pathway in the treatment of cancer

Histone deacetylase inhibitors (HDACis) show beneficial effects on different hematological malignancy subtypes. However, their impacts on treating solid tumors are still limited due to diverse resistance mechanisms. Recent studies have found that the feedback activation of BRD4-LIFR-JAK1-STAT3 pathway after HDACi incubation is a vital mechanism inducing resistance of specific solid tumor cells to HDACis. This review summarizes the recent development of multi-target HDACis that can concurrently block BRD4-LIFR-JAK1-STAT3 pathway. Moreover, our findings hope to shed novel lights on developing novel multi-target HDACis with reduced BRD4-LIFR-JAK1-STAT3-mediated drug resistance in some tumors.

Combined effects of naringin and doxorubicin on the JAK/STAT signaling pathway reduce the development and spread of breast cancer cells

Breast cancer therapy options are limited due to its late diagnosis and poor prognosis. Doxorubicin is the fundamental therapy approach for this disease. Because chemotherapy has numerous adverse effects, the scope of the existing research was to appraise the synergetic effect of doxorubicin and naringin and explore the underlying mechanism. The cytotoxicity of doxorubicin and naringin on MCF-7 was monitored. Furthermore, the expression of STAT3 and JAK1 as well as the apoptotic and metastatic related genes (Bax, Bcl-2, Survivin, and VEGF) were conducted by immunoblotting assay and qRT-PCR. In addition, a wound healing test was utilized to appraise the migration and metastasis of MCF-7. Our results revealed that naringin and doxorubicin had a synergetic inhibitory influence on MCF-7 cells growth and migration. The synergetic action of doxorubicin and naringin effectively hindered the expression of STAT3, JAK1, Bcl-2, Survivin, and VEGF, with a boost in the level of Bax compared to cells treated with either doxorubicin or naringin. In conclusion, our findings imply that combining doxorubicin with naringin may be a favorable strategy for inhibiting the growth of breast cancer.

ZNF70 regulates IL-1β secretion of macrophages to promote the proliferation of HCT116 cells via activation of NLRP3 inflammasome and STAT3 pathway in colitis-associated colorectal cancer

Chronic inflammation is a key driver for colitis-associated colorectal cancer (CAC). It has been reported that inflammatory cytokines, such as IL-1β, could promote CAC. Zinc finger protein 70 (ZNF70) is involved in multiple biological processes. Here, we identified a previously unknown role for ZNF70 regulates macrophages IL-1β secretion to promote HCT116 proliferation in CAC, and investigated its underlying mechanism. We showed ZNF70 is much higher expressed in CAC tumor tissues compared with adjacent normal tissues in clinical CAC samples. Further experiments showed ZNF70 promoted macrophages IL-1β secretion and HCT116 proliferation. In LPS/ATP-stimulated THP-1 cells, we found ZNF70 activated NLRP3 inflammasome, resulting in robust IL-1β secretion. Interestingly, we discovered the ZnF domain of ZNF70 could interact with NLRP3 and decrease the K48-linked ubiquitination of NLRP3. Moreover, ZNF70 could activate STAT3, thereby promoting IL-1β synthesis. Noteworthy, ZNF70 enhanced proliferation by upregulating STAT3 activation in HCT116 cells cultured in the conditioned medium of THP-1 macrophages treated with LPS/ATP. Finally, the vivo observations were confirmed using AAV-mediated ZNF70 knockdown, which improved colitis-associated colorectal cancer in the AOM/DSS model. The correlation between ZNF70 expression and overall survival/IL-1β expression in colorectal cancer was verified by TCGA database. Taken together, ZNF70 regulates macrophages IL-1β secretion to promote the HCT116 cells proliferation via activation of NLRP3 inflammasome and STAT3 pathway, suggesting that ZNF70 may be a promising preventive target for treating in CAC.

Natural bioactive compounds and STAT3 against hepatocellular carcinoma: An update

Hepatocellular carcinoma (HCC) is a challenging and very fatal liver cancer. The signal transducer and activator of transcription 3 (STAT3) pathway is a crucial regulator of tumor development and are ubiquitously active in HCC. Therefore, targeting STAT3 has emerged as a promising approach for preventing and treating HCC. Various natural bioactive compounds (NBCs) have been proven to target STAT3 and have the potential to prevent and treat HCC as STAT3 inhibitors. Numerous kinds of STAT3 inhibitors have been identified, including small molecule inhibitors, peptide inhibitors, and oligonucleotide inhibitors. Due to the undesirable side effects of the conventional therapeutic drugs against HCC, the focus is shifted to NBCs derived from plants and other natural sources. NBCs can be broadly classified into the categories of terpenes, alkaloids, carotenoids, and phenols. Most of the compounds belong to the family of terpenes, which prevent tumorigenesis by inhibiting STAT3 nuclear translocation. Further, through STAT3 inhibition, terpenes downregulate matrix metalloprotease 2 (MMP2), matrix metalloprotease 9 (MMP9) and vascular endothelial growth factor (VEGF), modulating metastasis. Terpenes also suppress the anti-apoptotic proteins and cell cycle markers. This review provides comprehensive information related to STAT3 abrogation by NBCs in HCC with in vitro and in vivo evidences.

Polarization of M2 Tumor-Associated Macrophages (TAMs) in Cancer Immunotherapy

We have witnessed in the last decade new milestones in the treatment of various resistant cancers with new immunotherapeutic modalities. These advances have resulted in significant objective durable clinical responses in a subset of cancer patients. These findings strongly suggested that immunotherapy should be considered for the treatment of all subsets of cancer patients. Accordingly, the mechanisms underlying resistance to immunotherapy must be explored and develop new means to target these resistant factors. One of the pivotal resistance mechanisms in the tumor microenvironment (TME) is the high infiltration of tumor-associated macrophages (TAMs) that are highly immunosuppressive and responsible, in large part, of cancer immune evasion. Thus, various approaches have been investigated to target the TAMs to restore the anti-tumor immune response. One approach is to polarize the M2 TAMS to the M1 phenotype that participates in the activation of the anti-tumor response. In this review, we discuss the various and differential properties of the M1 and M2 phenotypes, the molecular signaling pathways that participate in the polarization, and various approaches used to target the polarization of the M2 TAMs into the M1 anti-tumor phenotype. These approaches include inhibitors of histone deacetylases, PI3K inhibitors, STAT3 inhibitors, TLR agonists, and metabolic reprogramming. Clearly, due to the distinct features of various cancers and their heterogeneities, a single approach outlined above might only be effective against some cancers and not others. In addition, targeting by itself may not be efficacious unless used in combination with other therapeutic modalities.

Research on the Regulatory Mechanism of Ginseng on the Tumor Microenvironment of Colorectal Cancer based on Network Pharmacology and Bioinformatics Validation

BACKGROUND

A network pharmacology study on the biological action of ginseng in the treatment of colorectal cancer (CRC) by regulating the tumor microenvironment (TME).

OBJECTIVES

To investigate the potential mechanism of action of ginseng in the treatment of CRC by regulating TME.

METHODS

This research employed network pharmacology, molecular docking techniques, and bioinformatics validation. Firstly, the active ingredients and the corresponding targets of ginseng were retrieved using the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), the Traditional Chinese Medicine Integrated Database (TCMID), and the Traditional Chinese Medicine Database@Taiwan (TCM Database@Taiwan). Secondly, the targets related to CRC were retrieved using Genecards, Therapeutic Target Database (TTD), and Online Mendelian Inheritance in Man (OMIM). Tertiary, the targets related to TME were derived from screening the GeneCards and National Center for Biotechnology Information (NCBI)-Gene. Then the common targets of ginseng, CRC, and TME were obtained by Venn diagram. Afterward, the Protein-protein interaction (PPI) network was constructed in the STRING 11.5 database, intersecting targets identified by PPI analysis were introduced into Cytoscape 3.8.2 software cytoHubba plugin, and the final determination of core targets was based on degree value. The OmicShare Tools platform was used to analyze the Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the core targets. Autodock and PyMOL were used for molecular docking verification and visual data analysis of docking results. Finally, we verified the core targets by Gene Expression Profiling Interactive Analysis (GEPIA) and Human Protein Atlas (HPA) databases in bioinformatics.

RESULTS

A total of 22 active ingredients and 202 targets were identified to be closely related to the TME of CRC. PPI network mapping identified SRC, STAT3, PIK3R1, HSP90AA1, and AKT1 as possible core targets. Go enrichment analysis showed that it was mainly involved in T cell co-stimulation, lymphocyte co-stimulation, growth hormone response, protein input, and other biological processes; KEGG pathway analysis found 123 related signal pathways, including EGFR tyrosine kinase inhibitor resistance, chemokine signaling pathway, VEGF signaling pathway, ErbB signaling pathway, PD-L1 expression and PD-1 checkpoint pathway in cancer, etc. The molecular docking results showed that the main chemical components of ginseng have a stable binding activity to the core targets. The results of the GEPIA database showed that the mRNA levels of PIK3R1 were significantly lowly expressed and HSP90AA1 was significantly highly expressed in CRC tissues. Analysis of the relationship between core target mRNA levels and the pathological stage of CRC showed that the levels of SRC changed significantly with the pathological stage. The HPA database results showed that the expression levels of SRC were increased in CRC tissues, while the expression of STAT3, PIK3R1, HSP90AA1, and AKT1 were decreased in CRC tissues.

CONCLUSION

Ginseng may act on SRC, STAT3, PIK3R1, HSP90AA1, and AKT1 to regulate T cell costimulation, lymphocyte costimulation, growth hormone response, protein input as a molecular mechanism regulating TME for CRC. It reflects the multi-target and multi-pathway role of ginseng in modulating TME for CRC, which provides new ideas to further reveal its pharmacological basis, mechanism of action and new drug design and development.

miR-133b Promotes Esophageal Squamous Cell Carcinoma Metastasis

BACKGROUND

Evaluation of biological changes at the molecular level has important clinical implications for improving the survival rate of esophageal squamous cell carcinoma (ESCC). Therefore, we plan to analyze and elucidate the expression of microRNA-133b (miR-133b), M2 pyruvate kinase (PKM2), and signal transducer and activator of transcription 3 (STAT3) in ESCC and their associated clinicopathological significance.

METHODS

The 72 patients with ESCC were selected as the experimental study group. Normal adjacent tissues (NAT) were matched as the control group. In this study, in situ hybridization was used to detect the expression of miR-133b in ESCC, and tissue expressions of PKM2 and STAT3 were detected by immunohistochemistry, and literature review was conducted.

RESULTS

Studies had shown that the positive expression of miR-133b in NAT was significantly higher than that in ESCC (χ2 = 9.007, P = .003). PKM2 and STAT3 in ESCC had a significantly higher positive expression levels than those of NAT (χ2 = 56.523, P = .000; χ2 = 72.939, P = .000). From correlation analysis, there was a negative correlation between miR-133b and PKM2(r = -0.515, P < .001), a negative correlation between miR-133b and STAT3(r = -0.314, P = .007), and a positive correlation between PKM2 and STAT3(r = 0.771, P < .001).

CONCLUSIONS

In ESCC, our study demonstrated that downregulation of miR-133b and upregulation of PKM2 and STAT3. We predict that miR-133b may inhibit the STAT3 pathway by downregulating PKM2.

Oligonucleotide-Based Therapeutics for STAT3 Targeting in Cancer-Drug Carriers Matter

High expression and phosphorylation of signal transducer and transcription activator 3 (STAT3) are correlated with progression and poor prognosis in various types of cancer. The constitutive activation of STAT3 in cancer affects processes such as cell proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. The importance of STAT3 in cancer makes it a potential therapeutic target. Various methods of directly and indirectly blocking STAT3 activity at different steps of the STAT3 pathway have been investigated. However, the outcome has been limited, mainly by the number of upstream proteins that can reactivate STAT3 or the relatively low specificity of the inhibitors. A new branch of molecules with significant therapeutic potential has emerged thanks to recent developments in the regulatory function of non-coding nucleic acids. Oligonucleotide-based therapeutics can silence target transcripts or edit genes, leading to the modification of gene expression profiles, causing cell death or restoring cell function. Moreover, they can reach untreatable targets, such as transcription factors. This review briefly describes oligonucleotide-based therapeutics that found application to target STAT3 activity in cancer. Additionally, this review comprehensively summarizes how the inhibition of STAT3 activity by nucleic acid-based therapeutics such as siRNA, shRNA, ASO, and ODN-decoy affected the therapy of different types of cancer in preclinical and clinical studies. Moreover, due to some limitations of oligonucleotide-based therapeutics, the importance of carriers that can deliver nucleic acid molecules to affect the STAT3 in cancer cells and cells of the tumor microenvironment (TME) was pointed out. Combining a high specificity of oligonucleotide-based therapeutics toward their targets and functionalized nanoparticles toward cell type can generate very efficient formulations.

Identification of novel STAT3 inhibitors for liver fibrosis, using pharmacophore-based virtual screening, molecular docking, and biomolecular dynamics simulations

The signal transducer and activator of transcription 3 (STAT3) plays a fundamental role in the growth and regulation of cellular life. Activation and over-expression of STAT3 have been implicated in many cancers including solid blood tumors and other diseases such as liver fibrosis and rheumatoid arthritis. Therefore, STAT3 inhibitors are be coming a growing and interesting area of pharmacological research. Consequently, the aim of this study is to design novel inhibitors of STAT3-SH3 computationally for the reduction of liver fibrosis. Herein, we performed Pharmacophore-based virtual screening of databases including more than 19,481 commercially available compounds and in-house compounds. The hits obtained from virtual screening were further docked with the STAT3 receptor. The hits were further ranked on the basis of docking score and binding interaction with the active site of STAT3. ADMET properties of the screened compounds were calculated and filtered based on drug-likeness criteria. Finally, the top five drug-like hit compounds were selected and subjected to molecular dynamic simulation. The stability of each drug-like hit in complex with STAT3 was determined by computing their RMSD, RMSF, Rg, and DCCM analyses. Among all the compounds Sa32 revealed a good docking score, interactions, and stability during the entire simulation procedure. As compared to the Reference compound, the drug-like hit compound Sa32 showed good docking scores, interaction, stability, and binding energy. Therefore, we identified Sa32 as the best small molecule potent inhibitor for STAT3 that will be helpful in the future for the treatment of liver fibrosis.

Antimetastatic activity of seongsanamide B in γ-irradiated human lung cancer

Lung cancer, which has a high incidence and mortality rates, often metastasizes and exhibits resistance to radiation therapy. Seongsanamide B has conformational features that suggest it has therapeutic potential; however, its antitumor activity has not yet been reported. We evaluated the possibility of seongsanamide B as a radiation therapy efficiency enhancer to suppress γ-irradiation-induced metastasis in non-small cell lung cancer. Seongsanamide B suppressed non-small cell lung cancer cell migration and invasion caused by γ-irradiation. Furthermore, it suppressed γ-irradiation-induced upregulation of Bcl-XL and its downstream signaling molecules, such as superoxide dismutase 2 (SOD2) and phosphorylated Src, by blocking the nuclear translocation of phosphorylated STAT3. Additionally, seongsanamide B markedly modulated the γ-irradiation-induced upregulation of E-cadherin and vimentin. Consistent with the results obtained in vitro, while seongsanamide B did not affect xenograft tumor growth, it significantly suppressed γ-irradiation-induced metastasis by inhibiting Bcl-XL/SOD2/phosphorylated-Src expression and modulating E-cadherin and vimentin expression in a mouse model. Thus, seongsanamide B may demonstrate potential applicability as a radiation therapy efficiency enhancer for lung cancer treatment.

Synthesis and Biological Evaluation of Novel 2-Amino-1,4-Naphthoquinone Amide-Oxime Derivatives as Potent IDO1/STAT3 Dual Inhibitors with Prospective Antitumor Effects

Indoleamine-2,3-dioxygenase 1 (IDO1) and signal transducer and activator of transcription 3 (STAT3) have emerged as significant targets in the tumor microenvironment for cancer therapy. In this study, we synthesized three novel 2-amino-1,4-naphthoquinone amide-oxime derivatives and identified them as dual inhibitors of IDO1 and STAT3. The representative compound NK3 demonstrated effective binding to IDO1 and exhibited good inhibitory activity (hIDO1 IC50 = 0.06 μM), leading to its selection for further investigation. The direct interactions between compound NK3 and IDO1 and STAT3 proteins were confirmed through surface plasmon resonance analysis. A molecular docking study of compound NK3 revealed key interactions between NK3 and IDO1, with the naphthoquinone-oxime moiety coordinating with the heme iron. In the in vitro anticancer assay, compound NK3 displayed potent antitumor activity against selected cancer cell lines and effectively suppressed nuclear translocation of STAT3. Moreover, in vivo assays conducted on CT26 tumor-bearing Balb/c mice and an athymic HepG2 xenograft model revealed that compound NK3 exhibited potent antitumor activity with low toxicity relative to 1-methyl-L-tryptophan (1-MT) and doxorubicin (DOX). Overall, these findings provided evidence that the dual inhibitors of IDO1 and STAT3 may offer a promising avenue for the development of highly effective drug candidates for cancer therapy.

Evaluation of premetastatic changes in lymph nodes(pN0) of oral tongue tumour: A prospective observational Study

Background: Tongue tumors show intra and inter-tumoral heterogenicity with high incidence, relapse and mortality rates necessitating further research.  Recurrence/metastasis that occurs  after surgical resection of primary cancer is often the reason for poor survival in these patients.  Lymph nodes are the most common site of metastasis in tongue tumors. Therefore, premetastatic molecular changes can be best evaluated in lymph nodes which may epitomize the earliest events in the metastasis cascades. The presence of circulating tumor cells(CTCs) in the absence of nodal disease (N0) may represent tumor aggressiveness, suggesting an immune escape which may have high metastatic potential. This trial  was developed  to investigate the earliest pre-metastatic changes which may regulate tumor dormancy and predict metastasis. A better understanding of organotropism or pre-metastatic changes can help in theragnostic, thereby  preventing the outbreak of overt metastasis.  Methods: A single-institutional prospective observational cohort study. This trial will be conducted at a tertiary care Centre (Amrita Institute of Medical Sciences Kochi).  Eligible patients will be enrolled after obtaining informed consent. The dissected lymph nodes will  be subjected to histopathological and immunohistochemical analyses for premetastatic niche (PMN) formation. In addition, circulating tumor cells will be evaluated before treatment and 6 months after treatment. The patients will be followed  up for a period of two years to correlate the findings with the recurrence-free survival. Expected results:  The pre-metastatic changes, if detected will  be  a predictive biomarker. It may help to define future drug targets for metastasis chemoprevention   . CTCs may  define the tumor aggressiveness ,there by  prognostication  and helps in better disease management. Ethics and dissemination: The study has received the following approval: Ethics Committee of Amrita School of Medicine (ECASM-AIMS-2022-048).Trial Registered Prospectively( CTRI/2022/03/041256 ) on 22/03/2022 under Clinical Trial Registry of India.

Effect of plant produced Anti-hIL-6 receptor antibody blockade on pSTAT3 expression in human peripheral blood mononuclear cells

As a response to invasion by pathogens, the secretion of interleukin 6 (IL-6) which is a cytokine, activates IL-6/JAKs/STAT3 intracellular signaling via., phosphorylation. Over expression of pSTAT3 induces IL-6 positive feedback loop causing cytokine release syndrome or cytokine storm. Plants have gained momentum as an alternative expression system. Hence, this study aims to produce mAb targeting human IL-6 receptor (hIL-6R) in Nicotiana benthamiana for down regulating its cellular signaling thus, decreasing the expression of pSTAT3. The variable regions of heavy and light chains of anti-hIL-6R mAb were constructed in pBYK2e geminiviral plant expression vector and transiently co-expressed in N. benthamiana. The results demonstrate the proper protein assembly of anti-hIL-6R mAb with highest expression level of 2.24 mg/g FW at 5 dpi, with a yield of 21.4 µg/g FW after purification. The purity and N-glycosylation of plant produced antibody was analyzed, including its specificity to human IL-6 receptor by ELISA. Additionally, we investigated the effect to pSTAT3 expression in human PBMC's by flow cytometry wherein, the results confirmed lower expression of pSTAT3 with increasing concentrations of plant produced anti-hIL-6R mAb. Although, further in vivo studies are key to unveil the absolute functionality of anti-hIL-6R, we hereby show the potential of the plant platform and its suitability for the production of this therapeutic antibody.

A Glance at Biogenesis and Functionality of MicroRNAs and Their Role in the Neuropathogenesis of Parkinson's Disease

MicroRNAs (miRNAs) are short, noncoding RNA transcripts. Mammalian miRNA coding sequences are located in introns and exons of genes encoding various proteins. As the central nervous system is the largest source of miRNA transcripts in living organisms, miRNA molecules are an integral part of the regulation of epigenetic activity in physiological and pathological processes. Their activity depends on many proteins that act as processors, transporters, and chaperones. Many variants of Parkinson's disease have been directly linked to specific gene mutations which in pathological conditions are cumulated resulting in the progression of neurogenerative changes. These mutations can often coexist with specific miRNA dysregulation. Dysregulation of different extracellular miRNAs has been confirmed in many studies on the PD patients. It seems reasonable to conduct further research on the role of miRNAs in the pathogenesis of Parkinson's disease and their potential use in future therapies and diagnosis of the disease. This review presents the current state of knowledge about the biogenesis and functionality of miRNAs in the human genome and their role in the neuropathogenesis of Parkinson's disease (PD)-one of the most common neurodegenerative disorders. The article also describes the process of miRNA formation which can occur in two ways-the canonical and noncanonical one. However, the main focus was on miRNA's use in in vitro and in vivo studies in the context of pathophysiology, diagnosis, and treatment of PD. Some issues, especially those regarding the usefulness of miRNAs in PD's diagnostics and especially its treatment, require further research. More standardization efforts and clinical trials on miRNAs are needed.

Adefovir Dipivoxil as a Therapeutic Candidate for Medullary Thyroid Carcinoma: Targeting RET and STAT3 Proto-Oncogenes

Aberrant gene expression is often linked to the progression of various cancers, making the targeting of oncogene transcriptional activation a potential strategy to control tumor growth and development. The RET proto-oncogene’s gain-of-function mutation is a major cause of medullary thyroid carcinoma (MTC), which is part of multiple endocrine neoplasia type 2 (MEN2) syndrome. In this study, we used a cell-based bioluminescence reporter system driven by the RET promoter to screen for small molecules that potentially suppress the RET gene transcription. We identified adefovir dipivoxil as a transcriptional inhibitor of the RET gene, which suppressed endogenous RET protein expression in MTC TT cells. Adefovir dipivoxil also interfered with STAT3 phosphorylation and showed high affinity to bind to STAT3. Additionally, it inhibited RET-dependent TT cell proliferation and increased apoptosis. These results demonstrate the potential of cell-based screening assays in identifying transcriptional inhibitors for other oncogenes.

Silibinin induces immunogenic cell death in cancer cells and enhances the induced immunogenicity by chemotherapy

Introduction: Silibinin is a natural flavonoid compound known to induce apoptosis in cancer cells. Despite silibinin's safety and efficacy as an anticancer drug, its effects on inducing immunogenic cell death (ICD) are largely unknown. Herein, we have evaluated the stimulating effects of silibinin on ICD in cancer cells treated with silibinin alone or in combination with chemotherapy. Methods: The anticancer effect of silibinin, alone or in combination with doxorubicin or oxaliplatin (OXP), was assessed using the MTT assay. Compusyn software was used to analyze the combination therapy data. Western blotting was conducted to examine the level of STAT3 activity. Flow cytometry was used to analyze calreticulin (CRT) and apoptosis. The heat shock protein (HSP70), high mobility group box protein1 (HMGB1), and IL-12 levels were assessed by ELISA. Results: Compared to the negative control groups, silibinin induced ICD in CT26 and B16F10 cells and significantly enhanced the induction of this type of cell death by doxorubicin, and these changes were allied with substantial increases in the level of damage-associated molecular patterns (DAMPs) including CRT, HSP70, and HMGB1. Furthermore, conditioned media from cancer cells exposed to silibinin and doxorubicin was found to stimulate IL-12 secretion in dendritic cells (DCs), suggesting the link of this treatment with the induction of Th1 response. Silibinin did not augment the ICD response induced by OXP. Conclusion: Our findings showed that silibinin can induce ICD and it potentiates the induction of this type of cell death induced by chemotherapy in cancer cells.

Advances in the role of STAT3 in macrophage polarization

The physiological processes of cell growth, proliferation, differentiation, and apoptosis are closely related to STAT3, and it has been demonstrated that aberrant STAT3 expression has an impact on the onset and progression of a number of inflammatory immunological disorders, fibrotic diseases, and malignancies. In order to produce the necessary biological effects, macrophages (M0) can be polarized into pro-inflammatory (M1) and anti-inflammatory (M2) types in response to various microenvironmental stimuli. STAT3 signaling is involved in macrophage polarization, and the research of the effect of STAT3 on macrophage polarization has gained attention in recent years. In order to provide references for the treatment and investigation of disorders related to macrophage polarization, this review compiles the pertinent signaling pathways associated with STAT3 and macrophage polarization from many fundamental studies.

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.

Long Non-coding RNA H19 Deteriorates Hypoxic-Ischemic Brain Damage by Interacting with MicroRNA-140-5p and STAT3

OBJECTIVE

Even though extensive studies have surveyed long non-coding RNA (lncRNA)-related networks in hypoxic-ischemic brain damage (HIBD), the concrete function of lncRNA H19 (H19) in HIBD is still in ambiguity. Therein, this work intends to decipher H19-related network of microRNA (miR)-140-5p and signal transducer and activator of transcription 3 (STAT3) in HIBD.

METHODS

Brain microvascular endothelial cells (BMECs) from BALB/c mice were isolated and induced by oxygen glucose deprivation (OGD). OGD-induced BMECs were transfected with depleted or restored H19, miR-140-5p or STAT3, and cell apoptosis, migration and angiogenesis were examined. H19, miR-140-5p and STAT3 expression and their internal connections were tested.

RESULTS

H19 and STAT3 were overexpressed while miR-140-5p was down-regulated in OGD-induced BMECs. H19 or STAT3 knockdown, or miR-140-5p restoration repressed apoptosis and improved migration and angiogenesis of OGD-induced BMECs. MiR-140-5p restoration negated the impacts of up-regulated H19 on OGD-induced BMECs. H19 bound to miR-140-5p to modulate STAT3 expression.

CONCLUSION

The work illustrates that depleting H19 or STAT3 or restoring miR-140-5p attenuates HIBD and supplies a novel perspective for HIBD management.

Anticancer activity of IRAK-4 inhibitors against canine lymphoid malignancies

The interleukin-1 receptor-related kinase 4 (IRAK4), downstream of myd88, plays an essential role in hyperactive TLR signaling seen in some B-cell lymphomas. In particular, efficient IRAK4 inhibitors of activated B-cell subtype of human diffuse large B-Cell lymphoma (DLBCL) are being developed. However, the anticancer effect of IRAK-4 inhibitors in veterinary medicine has not been elucidated. It is therefore explored in this study involving the GL-1 and CL-1 canine lymphoma cell lines in vitro. MyD88 expression was analysed using polymerase chain reaction. GL-1 and CL-1 cells were subjected to concentration- and time-dependent treatment with an IRAK-4 inhibitor and assessed for viability, TLR signalling association, and apoptosis using a cell counting Kit-8 assay, Western blotting, and flow cytometry. The GL-1 and CL-1 cells exhibited enhanced MyD88 expression, however, canine peripheral blood mononuclear cells (cPBMCs) did not. The IRAK-4 inhibitor reduced cell viability in a dose- and time-dependent manner, significantly reduced the phosphorylation of molecules associated with TLR signalling at IC₅₀ such as IRAK1, IRAK4, NF-κB and STAT3, and induced apoptosis in GL-1 and CL-1 cells. The anticancer effect of the IRAK-4 inhibitor on canine lymphoma cells is mediated by apoptosis via downregulation of TLR signalling. This article is protected by copyright. All rights reserved.

Minecoside promotes apoptotic progression through STAT3 inactivation in breast cancer cells

Breast cancer is one of the most common malignant tumors in women worldwide, and is a major cause of mortality and morbidity in cancer patients. Constitutive activation of STAT3 has been found in a variety of malignant tumors, including breast cancer. Since STAT3 activation is capable of regulating various important features of tumor cells, identification of a novel STAT3 inhibitor is considered a potential strategy for treating breast cancer. The aim of the present study was to examine whether minecoside (MIN), an active compound extracted from Veronica peregrina L., exerts an antitumor effect by inhibiting STAT3 signaling pathway in MDA-MB-231 cells. The results revealed that MIN inhibited the constitutive STAT3 activation in a dose- and time-dependent manner. MIN also blocked the nuclear translocation of STAT3 and suppressed STAT3-DNA binding. In addition, MIN downregulated the STAT3-mediated expression of proteins such as Bcl-xL, Bcl-2, CXCR4, VEGF, and cyclin D1. Subsequently, MIN promoted the caspase-dependent apoptosis in MDA-MB-231 cells. Overall, results of the present study provide evidence that MIN exerted anticancer activity via inhibition of the STAT3 signaling pathway. Further studies using animal models are required to determine the potential of this molecule as an anticancer drug.

Synthesis and Antiproliferative Activity of Ester Derivatives of Mogrol through JAK2/STAT3 Pathway

In attempt to enhance the antiproliferative activity of mogrol, two series of ester derivatives modified at C₃ -OH and C₁₁ -OH were designed and synthesized. The activity against human cancer cells including A549, NCI-H460 and CNE1 was screened by Cell Counting Kit-8 (CCK8) assay. According to the results, modifications of the mogrol core through introduction of different ester scaffolds drastically improved the cytotoxicity, and some of the derivatives exhibited even higher activity than the positive drug. Among them, compound M2h exhibited nearly 4 times more cytotoxic than 5-Fu against CNE1 cells, derivative M6c showed ten times higher activity with the IC₅₀ value of 10.59 μM than mogrol against NCI-H460 cells, and compound M6a which contained one 1,2,3-triazole motif showed the strongest activity with an three folds lower IC₅₀ value than mogrol. Furthermore, the most potent compound M2h could lead to cell cycle arrest at G2 phase on CNE1 cell lines and M6a induced G1 phase arrest on A549 cell lines. It was noteworthy that both M2h and M6a regulated signal transducer and activator of transcription 3 (STAT3) signal pathway through inhibiting phosphorylation of Janus Kinase 2 (JAK2) and STAT3, and simultaneously increasing the protein level of downstream cyclin p21.

Redox regulation of DUBs and its therapeutic implications in cancer

Reactive oxygen species (ROS) act as a double-edged sword in cancer, where low levels of ROS are beneficial but excessive accumulation leads to cancer progression. Elevated levels of ROS in cancer are counteracted by the antioxidant defense system. An imbalance between ROS generation and the antioxidant system alters gene expression and cellular signaling, leading to cancer progression or death. Post-translational modifications, such as ubiquitination, phosphorylation, and SUMOylation, play a critical role in the maintenance of ROS homeostasis by controlling ROS production and clearance. Recent evidence suggests that deubiquitinating enzymes (DUBs)-mediated ubiquitin removal from substrates is regulated by ROS. ROS-mediated oxidation of the catalytic cysteine (Cys) of DUBs, leading to their reversible inactivation, has emerged as a key mechanism regulating DUB-controlled cellular events. A better understanding of the mechanism by which DUBs are susceptible to ROS and exploring the ways to utilize ROS to pharmacologically modulate DUB-mediated signaling pathways might provide new insight for anticancer therapeutics. This review assesses the recent findings regarding ROS-mediated signaling in cancers, emphasizes DUB regulation by oxidation, highlights the relevant recent findings, and proposes directions of future research based on the ROS-induced modifications of DUB activity.

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.

Targeting Tumor-Stromal IL6/STAT3 Signaling through IL1 Receptor Inhibition in Pancreatic Cancer

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense, desmoplastic stroma and the consequent altered interactions between cancer cells and their surrounding tumor microenvironment (TME) that promote disease progression, metastasis, and chemoresistance. We have previously shown that IL6 secreted from pancreatic stellate cells (PSC) stimulates the activation of STAT3 signaling in tumor cells, an established mechanism of therapeutic resistance in PDAC. We have now identified the tumor cell-derived cytokine IL1α as an upstream mediator of IL6 release from PSCs that is involved in STAT3 activation within the TME. Herein, we show that IL1α is overexpressed in both murine and human PDAC tumors and engages with its cognate receptor IL1R1, which is strongly expressed on stromal cells. Further, we show that IL1R1 inhibition using anakinra (recombinant IL1 receptor antagonist) significantly reduces stromal-derived IL6, thereby suppressing IL6-dependent STAT3 activation in human PDAC cell lines. Anakinra treatment results in significant reduction in IL6 and activated STAT3 levels in pancreatic tumors from Ptf1a^Cre/+;LSL-Kras^G12D/+; Tgfbr2^flox/flox (PKT) mice. Additionally, the combination of anakinra with cytotoxic chemotherapy significantly extends overall survival compared with vehicle treatment or anakinra monotherapy in this aggressive genetic mouse model of PDAC. These data highlight the importance of IL1 in mediating tumor-stromal IL6/STAT3 cross-talk in the TME and provide a preclinical rationale for targeting IL1 signaling as a therapeutic strategy in PDAC.

Modulating tumor-associated macrophages to enhance the efficacy of immune checkpoint inhibitors: A TAM-pting approach

Tumor-associated macrophages (TAM) plasticity and diversity are both essential hallmarks of the monocyte-macrophage lineage and the tumor-derived inflammation. TAM exemplify the perfect adaptable cell with dynamic phenotypic modifications that reflect changes in their functional polarization status. Under several tumor microenvironment (TME)-related cues, TAM shift their polarization, hence promoting or halting cancer progression. Immune checkpoint inhibitors (ICI) displayed unprecedented clinical responses in various refractory cancers; but only approximately a third of patients experienced durable responses. It is, therefore, crucial to enhance the response rate of immunotherapy. Several mechanisms of resistance to ICI have been elucidated including TAM role with its essential immunosuppressive functions that reduce both anti-tumor immunity and the subsequent ICI efficacy. In the past few years, thorough research has led to a better understanding of TAM biology and innovative approaches can now be adapted through targeting macrophages' recruitment axis as well as TAM activation and polarization status within the TME. Some of these therapeutic strategies are currently being evaluated in several clinical trials in association with ICI agents. This combination between TAM modulation and ICI allows targeting TAM intrinsic immunosuppressive functions and tumor-promoting factors as well as overcoming ICI resistance. Hence, such strategies, with a better understanding of the mechanisms driving TAM modulation, may have the potential to optimize ICI efficacy.

Atiprimod triggered apoptotic cell death via acting on PERK/eIF2α/ATF4/CHOP and STAT3/NF-ΚB axis in MDA-MB-231 and MDA-MB-468 breast cancer cells

PURPOSE

The constitutive activation of STAT3 through receptor tyrosine kinases triggered breast cancer cell growth and invasion-metastasis. Atiprimod impacts anti-proliferative, anti-carcinogenic effects in hepatocellular carcinoma, lymphoma, multiple myeloma via hindering the biological activity of STAT3. Dose-dependent atiprimod evokes first autophagy as a survival mechanism and then apoptosis due to prolonged ER stress in pituitary adenoma cells. The therapeutic efficiency and mechanistic action of atiprimod in breast cancer cells have not been investigated yet. Thus, we aimed to modulate the pivotal role of ER stress in atiprimod-triggered apoptosis in MDA-MB-231 and MDA-MB-468 breast cancer cells.

RESULTS

Dose- and time-dependent atiprimod treatment inhibits cell viability and colony formation in MDA-MB-468 and MDA-MB-231 breast cancer cells. A moderate dose of atiprimod (2 μM) inhibited STAT3 phosphorylation at Tyr705 residue and also suppressed the total expression level of p65. In addition, nuclear localization of STAT1, 3, and NF-κB was prevented by atiprimod exposure in MDA-MB-231 and MDA-MB-468 cells. Atiprimod evokes PERK, BiP, ATF-4, CHOP upregulation, and PERK (Thr980), eIF2α (Ser51) phosphorylation's. However, atiprimod suppressed IRE1α-mediated Atg-3, 5, 7, 12 protein expressions and no alteration was observed on Beclin-1, p62 expression levels. PERK/eIF2α/ATF4/CHOP axis pivotal role in atiprimod-mediated G1/S arrest and apoptosis via Bak, Bax, Bim, and PUMA upregulation in MDA-MB-468 cells. Moreover, atiprimod renders MDA-MB-231 more vulnerable to type I programmed cell death by plasmid-mediated increased STAT3 expression.

CONCLUSION

Atiprimod induced prolonged ER stress-mediated apoptosis via both activating PERK/eIF2α/ATF4/CHOP axis and suppressing STAT3/NF-κB transcription factors nuclear migration in TBNC cells.

Synergistic Activity of the HSP90 Inhibitor Ganetespib With Lapatinib Reverses Acquired Lapatinib Resistance in HER2-Positive Breast Cancer Cells

Lapatinib is an FDA-approved EGFR and HER2 tyrosine kinase inhibitor for the treatment of HER2-positive breast cancer patients. However, its therapeutic efficacy is limited by primary or acquired resistance. In the present study, we established breast cancers cells with acquired lapatinib resistance and investigated the antitumor activity of the second-generation HSP90 inhibitor ganetespib in association with lapatinib in lapatinib-sensitive and -resistant cells. The combination treatment showed synergistic inhibition of HER and the downstream PI3K/Akt and Ras/MEK/ERK pathways, in addition to enhancing induction of early apoptotic cell death and G1 arrest in both parent and lapatinib-resistant cells in vitro. The joint administration of ganetespib and lapatinib depleted the aberrant nuclear transcription factor STAT3, a mediator of the cell cycle and apoptosis-related pathways that is probably involved in the lapatinib resistance of HER2-positive breast cancer cells. In conjunctive with the augmented inhibition of tumor growth observed in both SKBR3 and SKBR3-L xenografts compared to monotherapy, our data provide a sound preclinical basis for combination treatment with lapatinib and ganetespib for refractory HER2-positive breast cancer.

LRG1 Promotes Metastatic Dissemination of Melanoma through Regulating EGFR/STAT3 Signalling

Although less common, melanoma is the deadliest form of skin cancer largely due to its highly metastatic nature. Currently, there are limited treatment options for metastatic melanoma and many of them could cause serious side effects. A better understanding of the molecular mechanisms underlying the complex disease pathophysiology of metastatic melanoma may lead to the identification of novel therapeutic targets and facilitate the development of targeted therapeutics. In this study, we investigated the role of leucine-rich α-2-glycoprotein 1 (LRG1) in melanoma development and progression. We first established the association between LRG1 and melanoma in both human patient biopsies and mouse melanoma cell lines and revealed a significant induction of LRG1 expression in metastatic melanoma cells. We then showed no change in tumour cell growth, proliferation, and angiogenesis in the absence of the host Lrg1. On the other hand, there was reduced melanoma cell metastasis to the lungs in Lrg1-deficient mice. This observation was supported by the promoting effect of LRG1 in melanoma cell migration, invasion, and adhesion. Mechanistically, LRG1 mediates melanoma cell invasiveness in an EGFR/STAT3-dependent manner. Taken together, our studies provided compelling evidence that LRG1 is required for melanoma metastasis but not growth. Targeting LRG1 may offer an alternative strategy to control malignant melanoma.

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.

lncRNA TUG1 regulates angiogenesis via the miR‑204‑5p/JAK2/STAT3 axis in hepatoblastoma

Hepatoblastoma is the most common malignant hepatic tumour type with hypervascularity in early childhood. In recent decades, emerging evidence has proven that long non‑coding RNAs (lncRNAs) serve an important oncogenic role in the pathogenesis of hepatoblastoma. However, the underlying mechanism of lncRNA taurine upregulated 1 (TUG1) in the angiogenesis of hepatoblastoma remains unknown. The expression patterns of TUG1 and microRNA (miR)‑204‑5p were detected in hepatoblastoma tissues and cell lines via reverse transcription‑quantitative PCR and were analysed using a Pearson's correlation test. A tube formation assay was performed using human umbilical vein endothelial cells to assess the vasculogenic activity of treated HuH‑6 cells. ELISA was used to detect the level of the secretory proangiogenic factor VEGFA in the culture media of HuH‑6 cells. A dual luciferase reporter assay was performed to validate the binding relationships of TUG1/miR‑204‑5p and miR‑204‑5p/Janus kinase 2 (JAK2). Moreover, western blotting was conducted to measure the protein expression levels of VEGFA, phosphorylated (p)‑JAK2, JAK2, p‑STAT3 and STAT3. It was identified that TUG1 was upregulated, while miR‑204‑5p was downregulated in hepatoblastoma tissues and cells. TUG1 knockdown inhibited angiogenesis induced by hepatoblastoma cells. Furthermore, miR‑204‑5p was identified as a target of TUG1. The results demonstrated that TUG1 attenuated the inhibitory effect of miR‑204‑5p on the JAK2/STAT3 pathway and promoted angiogenesis in hepatoblastoma cells. In summary, TUG1 was upregulated in hepatoblastoma and suppressed miR‑204‑5p, thereby activating the downstream signalling pathway of JAK2/STAT3 to facilitate angiogenesis. The present findings will provide novel targets for the treatment of hepatoblastoma.

Discovery of STAT3 and Histone Deacetylase (HDAC) Dual-Pathway Inhibitors for the Treatment of Solid Cancer

Nowadays, simultaneous inhibition of multiple targets through drug combination is an important anticancer strategy owing to the complex mechanism behind tumorigenesis. Recent studies have demonstrated that the inhibition of histone deacetylases (HDACs) will lead to compensated activation of a notorious cancer-related drug target, signal transducer and activator of transcription 3 (STAT3), in breast cancer through a cascade, which probably limits the anti-proliferation effect of HDAC inhibitors in solid tumors. By incorporating the pharmacophore of the HDAC inhibitor SAHA (vorinostat) into the STAT3 inhibitor pterostilbene, a series of potent pterostilbene hydroxamic acid derivatives with dual-target inhibition activity were synthesized. An excellent hydroxamate derivate, compound 14, inhibited STAT3 (K_D = 33 nM) and HDAC (IC₅₀ = 23.15 nM) with robust potency in vitro. Compound 14 also showed potent anti-proliferation ability in vivo and in vitro. Our study provides the first STAT3 and HDAC dual-target inhibitor for further exploration.

Albendazole Exhibits Anti-Neoplastic Actions against Gastric Cancer Cells by Affecting STAT3 and STAT5 Activation by Pleiotropic Mechanism(s)

Albendazole (ABZ) has been reported to display anti-tumoral actions against various maliganncies, but possible impact of ABZ on gastric cancer has not been deciphered. As aberrant phosphorylation of STAT3 and STAT5 proteins can regulate the growth and progression of gastric cancer, we postulated that ABZ may interrupt the activation of these oncogenic transcription factors. We found that ABZ exposure abrogated STAT3/5 activation, inhibited phosphorylation of Janus-activated kinases 1/2 and Src and enhanced the levels of SHP-1 protein. Silencing of SHP-1 gene by small interfering RNA (siRNA) reversed the ABZ-promoted attenuation of STAT3 as well as STAT5 activation and cellular apoptosis. In addition, these effects were noted to be driven by an augmented levels of reactive oxygen species caused by drug-induced GSH/GSSG imbalance. Thus, the data indicates that ABZ can modulate the activation of STAT3 and STAT5 by pleiotropic mechanisms in gastric cancer cells.

Efficacy of combination treatment using YHO-1701, an orally active STAT3 inhibitor, with molecular-targeted agents on cancer cell lines

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in regulating cell growth, survival, and metastasis. STAT3 signaling is constitutively activated in various types of hematologic or solid malignancies. YHO-1701 has been developed as an orally available STAT3 inhibitor. Herein, YHO-1701 in combination with molecular-targeted agents was evaluated. Additive or synergistic effects were observed in a broad spectrum of “combination treatment + cell line” pairs. Of particular interest was the synergistic effect observed when YHO-1701 was combined with imatinib or dasatinib [breakpoint cluster region-abelson (BCR-ABL) inhibitors], osimertinib [epidermal growth factor receptor (EGFR) inhibitor], crizotinib, alectinib, or ceritinib [anaplastic lymphoma kinase (ALK) inhibitors]. The results further showed a close relationship between these synergistic effects and the cellular levels of the key molecules involved in the target pathways for YHO-1701 and each combination drug. The combination of YHO-1701 with alectinib resulted in significantly greater antitumor activity without exhibiting body weight loss in an NCI-H2228 [echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion] xenograft mouse model. Our results strongly suggest that the logical strategy in combination with the novel STAT3 inhibitor YHO-1701 and other mechanistically different targeted agents, could be a promising approach in future clinical settings.

Costunolide, a Sesquiterpene Lactone, Suppresses Skin Cancer via Induction of Apoptosis and Blockage of Cell Proliferation

Costunolide is a naturally occurring sesquiterpene lactone that demonstrates various therapeutic actions such as anti-oxidative, anti-inflammatory, and anti-cancer properties. Costunolide has recently emerged as a potential anti-cancer agent in various types of cancer, including colon, lung, and breast cancer. However, its mode of action in skin cancer remains unclear. To determine the anti-cancer potential of costunolide in skin cancer, human epidermoid carcinoma cell line A431 was treated with costunolide. A lactate dehydrogenase assay showed that costunolide diminished the viability of A431 cells. Apoptotic cells were detected by annexin V/propidium iodide double staining and Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay assay, and costunolide induced cell apoptosis via activation of caspase-3 as well as induction of poly-ADP ribose polymerase cleavage in A431 cells. In addition, costunolide elevated the level of the pro-apoptotic protein Bax while lowering the levels of anti-apoptotic proteins, including Bcl-2 and Bcl-xL. To address the inhibitory effect of costunolide on cell proliferation and survival, various signaling pathways, including mitogen-activated protein kinases, signal transducer and activator of transcription 3 (STAT3), nuclear factor κB (NF-κB), and Akt, were investigated. Costunolide activated the p38 and c-Jun N-terminal kinase pathways while suppressing the extracellular signal-regulated kinase (ERK), STAT3, NF-κB, and Akt pathways in A431 cells. Consequently, it was inferred that costunolide suppresses cell proliferation and survival via these signaling pathways. Taken together, our data clearly indicated that costunolide exerts anti-cancer activity in A431 cells by suppressing cell growth via inhibition of proliferation and promotion of apoptosis. Therefore, it may be employed as a potentially tumor-specific candidate in skin cancer treatment.

Physalis alkekengi var. franchetii Extracts Exert Antitumor Effects on Non-Small Cell Lung Cancer and Multiple Myeloma by Inhibiting STAT3 Signaling

Background

Physalis alkekengi var. franchetii is an herb that possesses various ethnopharmacological applications. Herein, our current study focuses on the antitumor effect of a combination of physalins, which are regarded as the most representative secondary metabolites from calyces of Physalis alkekengi var. franchetii.

Materials and Methods

We mainly investigated the antitumor activity of the physalins extracted from Physalis alkekengi var. franchetii on both solid and hematologic cancers. The main cells used in this study were NCI-H1975 and U266 cells. The major assays used were the CCK-8 assay, Western blot analyses, immunofluorescence assay and Annexin V assay, and a xenograft mouse model was used.

Results

The results showed that physalins exhibited a strong antitumoural effect on both non-small cell lung cancer (NSCLC) and multiple myeloma (MM) cells by suppressing constitutive STAT3 activity and further inhibiting the downstream target gene expression induced by STAT3 signaling, which resulted in the enhanced apoptosis of tumor cells. Moreover, physalins significantly reduced tumor growth in xenograft models of lung cancer.

Conclusion

Collectively, these findings demonstrated that the physalins from Physalis alkekengi var. franchetii may potentially act as cancer preventive or chemotherapeutic agents for NSCLC and MM by inhibiting the STAT3 signaling pathway. The present study served as a promising guide to further explore the precise mechanism of Physalis alkekengi var. franchetii in cancer treatment.

Natural Salicylates and Their Roles in Human Health

Salicylic acid (SA) is a plant hormone which plays a crucial role in the plant defense against various pathogens and abiotic stresses. Increasing reports suggest that this phenolic compound and its derivatives, collectively termed salicylates, not only regulate plant defense but also have beneficial effects on human health. Both natural and synthetic salicylates are known to have multiple targets in humans, thereby exhibiting various appreciating pharmacological roles, including anti-inflammatory, anticancer, neuroprotective, antidiabetic effects, and so on. The role of some salicylates, such as acetylsalicylic acid (aspirin), 5-aminosalicylic acid (mesalazine), and amorfrutins in human diseases has been well studied in vitro. However, their clinical significance in different diseases is largely unknown. Based on recent studies, five natural salicylates, including amorfrutin, ginkgolic acid, grifolic acid, tetrahydrocannabinolic acid, and cannabidiolic acid, showed potential roles in different challenging human diseases. This review summarizes together some of the recent information on multitarget regulatory activities of these natural salicylates and their pharmacological roles in human health.

An Electrophilic Deguelin Analogue Inhibits STAT3 Signaling in H-Ras-Transformed Human Mammary Epithelial Cells: The Cysteine 259 Residue as a Potential Target

Signal transducer and activator of transcription 3 (STAT3) is a point of convergence for numerous oncogenic signals that are often constitutively activated in many cancerous or transformed cells and some stromal cells in the tumor microenvironment. Persistent STAT3 activation in malignant cells stimulates proliferation, survival, angiogenesis, invasion, and tumor-promoting inflammation. STAT3 undergoes activation through phosphorylation on tyrosine 705, which facilitates its dimerization. Dimeric STAT3 translocates to the nucleus, where it regulates the transcription of genes involved in cell proliferation, survival, etc. In the present study, a synthetic deguelin analogue SH48, discovered by virtual screening, inhibited the phosphorylation, nuclear translocation, and transcriptional activity of STAT3 in H-ras transformed human mammary epithelial MCF-10A cells (MCF10A-ras). We speculated that SH48 bearing an α,β-unsaturated carbonyl group could interact with a thiol residue of STAT3, thereby inactivating this transcription factor. Non-electrophilic analogues of SH48 failed to inhibit STAT3 activation, lending support to the above supposition. By utilizing a biotinylated SH48, we were able to demonstrate the complex formation between SH48 and STAT3. SH48 treatment to MCF10A-ras cells induced autophagy, which was verified by staining with a fluorescent acidotropic probe, LysoTracker Red, as well as upregulating the expression of LC3II and p62. In conclusion, the electrophilic analogue of deguelin interacts with STAT3 and inhibits its activation in MCF10A-ras cells, which may account for its induction of autophagic death.

STAT3 gain-of-function mutation in a patient with pulmonary Mycobacterium abscessus infection

Background

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor involved in cellular proliferation, apoptosis, and differentiation. Mutations in the STAT3 gene have been associated with dysregulation of the immune system giving rise to primary immunodeficiency syndromes (PID). Clinically, patients may present with very broad manifestations, and its diagnosis is usually very challenging. Proper treatment remains unclear, and limited options are available.

Methods

We report an adult male patient with long-standing history of immunodeficiency, who was found to have Mycobacterium abscessus infection. Two-hundred and seven immunogenes were sequenced using next-generation sequencing technology (NGS).

Results

A STAT3 heterozygous missense pathologic variant was identified in the patient located in the transactivation domain (TA) of STAT3, associated with a gain of functionality, leading to recurrent bronchopulmonary infections, and involvement of multiple organ systems.

Conclusions

Severe cases of autoimmunity should prompt for evaluation of PIDs in the setting of genetic mutations. Anti-IL-6 therapy may benefit patients with STAT3 GOF mutations. These patients should also be screened for lymphoproliferative disorders.

A novel small molecule STAT3 inhibitor SLSI-1216 suppresses proliferation and tumor growth of triple-negative breast cancer cells through apoptotic induction

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer, characterized by the lack of expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Owing to the absence of molecular targets, there are limited treatment options, and TNBC patients exhibit high mortality rates. Signal transducer and activator of transcription 3 (STAT3) is overexpressed and aberrantly activated in TNBC cells. Therefore, inhibition of STAT3-mediated signaling provides a potential strategy for the treatment of TNBC. In this study, A series of synthetic derivatives of SLSI-1 (a STAT3 inhibitor) were designed and evaluated for antitumor activity in TNBC cells. A novel derivative (SLSI-1216) exhibited the most potent anti-proliferative activity. SLSI-1216 effectively inhibited STAT3 activity and activation of STAT3, leading to the downregulation of AXL, a downstream target of STAT3 and epithelial-mesenchymal transition (EMT) progression. The inhibition of EMT by SLSI-1216 was associated with modulation of E-cadherin and N-cadherin. Furthermore, SLSI-1216 induced apoptosis by targeting STAT3 and effectively inhibited tumor growth in vivo. These findings suggest that SLSI-1216, as a potential inhibitor of STAT3, may be a promising therapeutic agent for TNBC.

BP-1-102 and silencing of Fascin-1 by RNA interference inhibits the proliferation of mouse pituitary adenoma AtT20 cells via the signal transducer and activator of transcription 3/fascin-1 pathway

INTRODUCTION

The expression levels of signal transducer and activator of transcription 3 (STAT3) protein and Fascin-1 were inhibited using the STAT3 inhibitor BP-1-102 and RNA interference, respectively, to investigate the expression of AtT20 in mouse pituitary cells. The proliferative capacity and related molecular mechanisms of pituitary tumor cells were then analyzed.

METHODS

Mouse AtT20 pituitary adenoma cells were divided into a control group (Pa group), a STAT3 inhibitor vehicle group (PA + DMSO group), a STAT3 inhibitor group (PA + BP-1-102 group), a Fascin-1 negative control group (PA + neg-siRNA group) and a Fascin-1 silenced group (PA + Fascin-siRNA group). The related protein expression and cell proliferation of the five groups were measured using immunofluorescence, Western blot and real-time RT-PCR, whereas their apoptosis and cell cycle were evaluated using CCK-8 and flow cytometry.

RESULTS

Proliferation of AtT20 cells is inhibited with BP-1-102 enhanced apoptosis, at the same time reduced the expression of Fascin-1 and N-cadherin, and increased the expression of E-cadherin. After inhibiting Fascin-1, the expression of STAT3 decreased, the expression of N-cadherin decreased and the expression of E-cadherin increased.

CONCLUSIONS

BP-1-102 is a novel drug with a great potential in pituitary tumors. Given their important roles in the growth of pituitary adenomas, STAT3 and Fascin-1 can be used as new treatment targets.