JAK/STAT: Why choose a classical or an alternative pathway when you can have both?

STAT3 Signaling Pathway in Health and Disease

Signal transducer and activator of transcription 3 (STAT3) is a critical transcription factor involved in multiple physiological and pathological processes. While STAT3 plays an essential role in homeostasis, its persistent activation has been implicated in the pathogenesis of various diseases, particularly cancer, bone-related diseases, autoimmune disorders, inflammatory diseases, cardiovascular diseases, and neurodegenerative conditions. The interleukin-6/Janus kinase (JAK)/STAT3 signaling axis is central to STAT3 activation, influencing tumor microenvironment remodeling, angiogenesis, immune evasion, and therapy resistance. Despite extensive research, the precise mechanisms underlying dysregulated STAT3 signaling in disease progression remain incompletely understood, and no United States Food and Drug Administration (USFDA)-approved direct STAT3 inhibitors currently exist. This review provides a comprehensive evaluation of STAT3's role in health and disease, emphasizing its involvement in cancer stem cell maintenance, metastasis, inflammation, and drug resistance. We systematically discuss therapeutic strategies, including JAK inhibitors (tofacitinib, ruxolitinib), Src Homology 2 domain inhibitors (S3I-201, STATTIC), antisense oligonucleotides (AZD9150), and nanomedicine-based drug delivery systems, which enhance specificity and bioavailability while reducing toxicity. By integrating molecular mechanisms, disease pathology, and emerging therapeutic interventions, this review fills a critical knowledge gap in STAT3-targeted therapy. Our insights into STAT3 signaling crosstalk, epigenetic regulation, and resistance mechanisms offer a foundation for developing next-generation STAT3 inhibitors with greater clinical efficacy and translational potential.

YTHDF2 promotes the metastasis of oral squamous cell carcinoma through the JAK-STAT pathway

RNA-binding proteins act as crucial mediators between N6-methyladenosine (m6A) modification and RNA function, playing a significant role in the recurrence and metastasis of oral squamous cell carcinoma (OSCC). YTHDF2, the first identified RNA-binding protein, has been shown to be closely associated with the prognosis of certain types of cancer. However, the role of YTHDF2 in OSCC and its underlying molecular mechanisms remain poorly understood and require further investigation. First, we analysed the expression levels of YTHDF2 and examined its correlation with clinical features using public databases and OSCC patient samples. Subsequently, a series of in vitro functional experiments were conducted to assess the effects of YTHDF2 on the proliferation, migration, and invasion capabilities of OSCC cells. Additionally, RNA-seq analysis was utilized to investigate the signalling pathways modulated by YTHDF2, which was further supported by experimental validation. Our findings revealed that YTHDF2 expression was significantly elevated in OSCC tissues and cells, with levels closely correlated with the clinical stage, pathological grade, and survival time of patients. The knockdown of YTHDF2 resulted in a significant reduction in the proliferation, migration, and invasion abilities of OSCC cells. Furthermore, RNA sequencing data indicated that silencing YTHDF2 suppressed the JAK-STAT signalling pathway, and the use of STAT3 activators reversed this suppressive effect in OSCC cells. Our study demonstrated that YTHDF2 promotes the proliferation, metastasis, and invasion of OSCC by positively regulating the JAK-STAT signalling pathway, suggesting that YTHDF2 could serve as a potential prognostic marker for the diagnosis and treatment of OSCC.

Alloferon and IL-22 receptor expression regulation on the pathogenesis of imiquimod-induced psoriasis

Psoriasis is an immune-mediated inflammatory skin disease. IL-22, a proinflammatory cytokine, is implicated in psoriasis pathogenesis; however, there is currently no established biological treatment targeting IL-22 or its receptor, IL-22Rα. Alloferon is a short peptide that has an antiinflammatory effect on skin disorders; however, little is known about its anti-inflammatory activity in psoriasis. We investigated the regulatory role of alloferon in the development of psoriasis in an imiquimod (IMQ)-induced psoriasis model through the regulation of IL-22Rα expression. The expression of IL-22Rα was analyzed by immunofluorescence staining in primary human keratinocytes. The effect of alloferon on the development of psoriasis was investigated in IMQ-induced wild-type and IL-22Rα KO mice. We found that alloferon decreased the expression of IL-22Rα in psoriasis-like keratinocytes treated with TNF-α, while epidermal hyperplasia was observed in IMQ-induced wild-type and IL-22Rα KO mice. In addition, the expression of IL-1β, IL-19, and IL-33 was suppressed when IL-22Rα KO mice were treated with alloferon. The findings of this study indicate that alloferon could be an effective potential drug for the treatment of psoriasis by interrupting IL-22 signaling and factors related to skin inflammation.

STAT3-related lncRNAs in colorectal cancer progression; Special focus on immune cell's evasion

Colorectal cancer (CRC) is globally ranked as the third leading cause of cancer-related deaths in both men and women. There is an urgent need for novel biomarkers to facilitate early diagnosis and enhance patient care, thereby improving treatment response and reducing mortality rates. Signal transducer and activator of transcription 3 (STAT3) is essential for controlling the anti-tumor immune response since it is a hub for several oncogenic signaling pathways. In the tumor environment, STAT3 is widely overactivated in both malignant and non-cancerous cells. It is involved in suppressing the expression of critical immune activation regulators and encouraging the synthesis of immunosuppressive substances. Long noncoding RNAs (lncRNAs), a kind of non-coding RNA, are critical for CRC development, apoptosis, and metastasis because they influence important signaling pathways such as STAT3 signaling and contribute to gene regulation at the epigenetic, transcriptional, and post-transcriptional levels. Moreover, lncRNAs have a significant role in modifying the TME and control the expression of important immunological checkpoints, such as PD-L1. Therefore, a comprehensive understanding of the regulatory roles of lncRNAs is crucial for identifying diagnostic, prognostic, and predictive biomarkers for CRC. Thus, the objective of the present review study is to provide a comprehensive overview of the interaction between the STAT3 signaling pathway and various lncRNAs, as well as their implications for apoptosis, metastasis, and immune evasion in CRC.

Rlip76 in ageing and Alzheimer's disease: Focus on oxidative stress and mitochondrial mechanisms

RLIP76 (Rlip), a stress-responsive protein, plays a multifaceted role in cellular function. This protein acts primarily as a glutathione-electrophile conjugate (GS-E) transporter, crucial for detoxifying hazardous compounds and converting them into mercapturic acids. RLIP76 also modulates cytoskeletal motility and membrane plasticity through its role in the Ral-signaling pathway, interacting with RalA and RalB, key small GTPases involved in growth and metastasis. Beyond its ATP-dependent transport functions in various tissues, RLIP76 also demonstrates GTPase Activating Protein (GAP) activity towards Rac1 and Cdc42, with a preference for Ral-GTP over Ral-GDP. Its functions span critical physiological processes including membrane dynamics, oxidative stress response, and mitochondrial dynamics. The protein's widespread expression and evolutionary conservation underscore its significance. Our lab discovered that Rlip interacts with Alzheimer's disease (AD) proteins, amyloid beta and phosphorylated and induce oxidative stress, mitochondrial dysfnction and synaptic damage in AD. Our in vitro studies revealed that overexpression of Rlip reduces mitochondrial abnormalities. Further, our in vivo studies (Rlip+/- mice) revealed that a partial reduction of Rlip in mice (Rlip+/-), leads to mitochondrial abnormalities, elevated oxidative stress, and cognitive deficits resembling late-onset AD, emphasizing the protein's crucial role in neuronal health and disease. Finally, we discuss the experimental cross-breedings of overexpression of mice Rlip TG/TG or Rlip + /- mice with Alzheimer's disease models - earlyonset 5XFAD, late-onset APPKI and Tau transgenic mice, providing new insights into RLIP76's role in AD progression and development. This review summarizes RLIP76's structure, function, and cellular pathways, highlighting its implications in AD and its potential as a therapeutic target.

Functional Involvement of Signal Transducers and Activators of Transcription in the Pathogenesis of Influenza A Virus

Signal transducers and activators of transcription (STATs) function both as signal transducers and transcription regulators. STAT proteins are involved in the signaling pathways of cytokines and growth factors; thus, they participate in various life activities and play especially critical roles in antiviral immunity. Convincing evidence suggests that STATs can establish innate immune status through multiple mechanisms, efficiently eliminating pathogens. STAT1 and STAT2 can activate the antiviral status by regulating the interferon (IFN) signal. In turn, suppressor of cytokine signaling-1 (SOCS1) and SOCS3 can modulate the activation of STATs and suppress the excessive antiviral immune response. STAT3 not only regulates the IFN signal, but also transduces Interleukin-6 (IL-6) to stimulate the host antiviral response. The function of STAT4 and STAT5 is related to CD4+ T helper (Th) cells, and the specific mechanism of STAT5 remains to be studied. STAT6 mainly exerts antiviral effects by mediating IL-4 and IL-13 signaling. Here, we reviewed the recent findings regarding the critical roles of STATs in the interactions between the host and viral infection, especially influenza A virus (IAV) infection. We also discuss the molecular mechanisms underlying their functions in antiviral responses.

Structure-function of type I and III interferons

Type I and type III interferons (IFNs) are major components in activating the innate immune response. Common to both are two distinct receptor chains (IFNAR1/IFNAR2 and IFNLR1/IL10R2), which form ternary complexes upon binding their respective ligands. This results in close proximity of the intracellularly associated kinases JAK1 and TYK2, which cross phosphorylate each other, the associated receptor chains, and signal transducer and activator of transcriptions, with the latter activating IFN-stimulated genes. While there are clear similarities in the biological responses toward type I and type III IFNs, differences have been found in their tropism, tuning of activity, and induction of the immune response. Here, we focus on how these differences are embedded in the structure/function relations of these two systems in light of the recent progress that provides in-depth information on the structural assembly of these receptors and their functional implications and how these differ between the mouse and human systems.

[Effectiveness of tofacitinib combined with iguratimod in the treatment of difficult-to-treat moderate-to-severe rheumatoid arthritis]

OBJECTIVE

To investigate the efficacy and safety of iguratimod combined with tofacitinib in patients with difficult-to-treat moderate-to-severe rheumatoid arthritis (RA).

METHODS

In this prospective clinical study, 30 patients with difficult-to-treat moderate-to-severe RA who attended the Department of Rheumatology and Immunology of Shanxi Province Fenyang Hospital from September 2021 to June 2022 were selected. Twenty-three patients enrollment had been treated with 2 or more conventional synthetic disease modifying anti-rheumatic drugs (DMARDs) for more than 6 months. At least, methotrexate or leflunomide was included. Seven patients were treated with conventional synthetic DMARDs combined with tumor necrosis factor antagonists. Because all the patients had not reached the target of treatment, the combination treatment regimen of DMARDs was changed to iguratimod and tofacitinib. The observation period was 12 weeks. Clinical data were collected before and after treatment. At the end of 4 weeks, 8 weeks and 12 weeks, the clinical data were collected such as swollen joints count (SJC), tender joints count (TJC), time of morning stiffness, clinical disease activity index (CDAI), health status assessment questionnaire (HAQ), and 28-joint disease activity score (DAS28) were included. We collected laboratory indicators, recorded the patient's medication, and observed some changes to see if any adverse drug reactions occurred during the treatment.

RESULTS

There were significant differences in erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), platelet (PLT), SJC, TJC, DAS28 based on ESR(DAS28-ESR), time of morning stiffness, HAQ, CDAI, and anti-cyclic citrullinated peptide antibody before and after treatment. The differences had statistical significance (P < 0.05). There was no statistical differences in globulin before and after treatment (P>0.05). During the treatment of iguratimod combined with tofacitinib, there was no serious adverse reactions such as leukopenia, significant elevation of liver enzymes, allergy or thromboemblolic events that occurred in all the patients.

CONCLUSION

Iguratimod combined with tofacitinib in the treatment of difficult-to-treat moderate-to-severe RA may have efficacy. The machanism was improving the patients' recent clinical symptoms by reducing inflammatory indexes. This combination treatment regimen with iguratimod and tofacitinib has a good safety profile.

Regulation of the JAK/STAT signaling pathway in spinal cord injury: an updated review

Cytokines are involved in neural homeostasis and pathological processes associated with neuroinflammation after spinal cord injury (SCI). The biological effect of cytokines, including those associated with acute or chronic SCI pathologies, are the result of receptor-mediated signaling through the Janus kinases (JAKs) as well as the signal transducers and activators of transcription (STAT) DNA-binding protein families. Although therapies targeting at cytokines have led to significant changes in the treatment of SCI, they present difficulties in various aspects for the direct use by patients themselves. Several small-molecule inhibitors of JAKs, which may affect multiple pro-inflammatory cytokine-dependent pathways, as well as STATs, are in clinical development for the treatment of SCI. This review describes the current understanding of the JAK-STAT signaling in neuroendocrine homeostasis and diseases, together with the rationale for targeting at this pathway for the treatment of SCI.

Insect-pathogen crosstalk and the cellular-molecular mechanisms of insect immunity: uncovering the underlying signaling pathways and immune regulatory function of non-coding RNAs

Multicellular organisms are constantly subjected to pathogens that might be harmful. Although insects lack an adaptive immune system, they possess highly effective anti-infective mechanisms. Bacterial phagocytosis and parasite encapsulation are some forms of cellular responses. Insects often defend themselves against infections through a humoral response. This phenomenon includes the secretion of antimicrobial peptides into the hemolymph. Specific receptors for detecting infection are required for the recognition of foreign pathogens such as the proteins that recognize glucans and peptidoglycans, together referred to as PGRPs and βGRPs. Activation of these receptors leads to the stimulation of signaling pathways which further activates the genes encoding for antimicrobial peptides. Some instances of such pathways are the JAK-STAT, Imd, and Toll. The host immune response that frequently accompanies infections has, however, been circumvented by diseases, which may have assisted insects evolve their own complicated immune systems. The role of ncRNAs in insect immunology has been discussed in several notable studies and reviews. This paper examines the most recent research on the immune regulatory function of ncRNAs during insect-pathogen crosstalk, including insect- and pathogen-encoded miRNAs and lncRNAs, and provides an overview of the important insect signaling pathways and effector mechanisms activated by diverse pathogen invaders.

Pharmacological impact of microRNAs in head and neck squamous cell carcinoma: Prevailing insights on molecular pathways, diagnosis, and nanomedicine treatment

Head and neck squamous cell carcinoma is a disease that most commonly produce tumours from the lining of the epithelial cells of the lips, larynx, nasopharynx, mouth, or oro-pharynx. It is one of the most deadly forms of cancer. About one to two percent of all neo-plasm-related deaths are attributed to head and neck squamous cell carcinoma, which is responsible for about six percent of all cancers. MicroRNAs play a critical role in cell proliferation, differentiation, tumorigenesis, stress response, triggering apoptosis, and other physiological process. MicroRNAs regulate gene expression and provide new diagnostic, prognostic, and therapeutic options for head and neck squamous cell carcinoma. In this work, the role of molecular signaling pathways related to head and neck squamous cell carcinoma is emphasized. We also provide an overview of MicroRNA downregulation and overexpression and its role as a diagnostic and prognostic marker in head and neck squamous cell carcinoma. In recent years, MicroRNA nano-based therapies for head and neck squamous cell carcinoma have been explored. In addition, nanotechnology-based alternatives have been discussed as a promising strategy in exploring therapeutic paradigms aimed at improving the efficacy of conventional cytotoxic chemotherapeutic agents against head and neck squamous cell carcinoma and attenuating their cytotoxicity. This article also provides information on ongoing and recently completed clinical trials for therapies based on nanotechnology.

Identifying hub genes, key pathways and key immune-related genes in Peyronie's disease by integrated bioinformatic analysis

Scarring diseases, such as Peyronie's disease (PD), usually lead to disorders in the immune system. Previous studies suggested that the PD process was regulated by immune signaling. However, the pathogenetic mechanism remains incompletely characterized. This article used bioinformatic approaches to identify hub genes, key pathways and key immune-related genes that play essential roles in PD pathogenesis. Two Gene Expression Omnibus (GEO) datasets, GSE126005 and GSE146500, were used to analyse the transcriptional profiling in both PD and normal samples. R software was applied to examine the difference in the expression of hub genes and key immune-related genes. The candidates for hub genes were further validated through protein-protein interactions (PPIs), gene correlation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. In addition, candidate miRNA‒mRNA pairs were functionally assessed. A total of 39 candidate genes were identified, the expression levels of which in PD fibroblast cells were different from those in normal cells (16 showed reduced expression in PD and 21 candidates overexpressed in PD). We found that these genes could interact with each other through PPI analysis. According to the functional enrichment analysis, the candidates may regulate some major biological processes, including cytokine‒cytokine receptor interactions and the JAK-STAT signaling pathway. IL6, IL21R, IFNE, CXCL2, EGF, and ANGPTL5 were identified as key immune-related genes. The findings may help understand the role of immunologic contributors in PD, thus shedding light on the development of more effective strategies to prevent and treat this kind of disease.

Combined biological effects and lung proteomics analysis in mice reveal different toxic impacts of electronic cigarette aerosol and combustible cigarette smoke on the respiratory system

Combustible cigarettes produce many toxic substances that have been linked to diseases, such as lung cancer and chronic obstructive pulmonary disease. For those smokers unable or unwilling to quit, electronic cigarettes (e-cigarettes) could be used as an alternative to cigarettes. However, the effects and mechanisms of e-cigarette aerosol (ECA) on respiratory function have not been fully elucidated, and in vivo studies of its safety are limited compared to cigarette smoke (CS). In this article, we chose nicotine levels as dosing references and C57BL/6 mice for a 10-week subchronic inhalation toxicity study. A comprehensive set of toxicological endpoints was used to study the effect of exposure. Both CS (6 mg/kg) and ECA (6 or 12 mg/kg) inhalation had decreased the animal's lung function and increased levels of inflammation markers, along with pathological changes in the airways and lungs, with ECA displaying a relatively small effect at the same dose. Proteomic analysis of lung tissue showed greater overall protein changes by CS than that of ECA, with more severe inflammatory network perturbations. Compared with ECA, KEGG analysis of CS revealed upregulation of more inflammatory and virus-related pathways. Protein-protein interactions (PPI) showed that both ECA and CS significantly changed ribosome and complement system-related proteins in mouse lung tissue. The results support that e-cigarette aerosol is less harmful to the respiratory system than cigarette smoke at the same dose using this animal model, thus providing additional evidence for the relative safety of e-cigarettes.

Synthetic mimetics assigned a major role to IFNAR2 in type I interferon signaling

Type I interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling. Moreover, replication of vesicular stomatitis virus (VSV) in a cell culture-based viral infection model using MC57 cells was significantly inhibited after stimulation with synthetic ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supports this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.

The molecular mechanisms and targeting strategies of transcription factors in cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma consists of a cluster of malignant biliary tumors that tend to have a poor prognosis, ranking as the second most prevalent type of liver cancer, and their incidence rate has increased globally recently. The high-frequency driving mutations of cholangiocarcinoma, such as KRAS/IDH1/ARID1A/P53, imply the epigenetic instability of cholangiocarcinoma, leading to the dysregulation of various related transcription factors, thus affecting the occurrence and development of cholangiocarcinoma. Increasingly evidence indicates that the high heterogeneity and malignancy of cholangiocarcinoma are closely related to the dysregulation of transcription factors which promote cell proliferation, invasion, migration, angiogenesis, and drug resistance through reprogrammed transcriptional networks. It is of great significance to further explore and summarize the role of transcription factors in cholangiocarcinoma.

AREAS COVERED

This review summarizes the oncogenic or tumor suppressive roles of key transcription factors in regulating cholangiocarcinoma progression and the potential targeting strategies of transcription factors in cholangiocarcinoma.

EXPERT OPINION

Cholangiocarcinoma is a type of cancer highly influenced by transcriptional regulation, specifically transcription factors and epigenetic regulatory factors. Targeting transcription factors could be a potential and important strategy that is likely to impact future cholangiocarcinoma treatment.