Repurposing the selective estrogen receptor modulator bazedoxifene to suppress gastrointestinal cancer growth

Combination of bazedoxifene with chemotherapy and SMAC-mimetics for the treatment of colorectal cancer

Excessive STAT3 signalling via gp130, the shared receptor subunit for IL-6 and IL-11, contributes to disease progression and poor survival outcomes in patients with colorectal cancer. Here, we provide evidence that bazedoxifene inhibits tumour growth via direct interaction with the gp130 receptor to suppress IL-6 and IL-11-mediated STAT3 signalling. Additionally, bazedoxifene combined with chemotherapy synergistically reduced cell proliferation and induced apoptosis in patient-derived colon cancer organoids. We elucidated that the primary mechanism of anti-tumour activity conferred by bazedoxifene treatment occurs via pro-apoptotic responses in tumour cells. Co-treatment with bazedoxifene and the SMAC-mimetics, LCL161 or Birinapant, that target the IAP family of proteins, demonstrated increased apoptosis and reduced proliferation in colorectal cancer cells. Our findings provide evidence that bazedoxifene treatment could be combined with SMAC-mimetics and chemotherapy to enhance tumour cell apoptosis in colorectal cancer, where gp130 receptor signalling promotes tumour growth and progression.

Mechanisms of cellular crosstalk in the gastric tumor microenvironment are mediated by YAP1 and STAT3

Deregulation of the Hippo pathway is a driver for cancer progression and treatment resistance. In the context of gastric cancer, YAP1 is a biomarker for poor patient prognosis. Although genomic tumor profiling provides information of Hippo pathway activation, the present study demonstrates that inhibition of Yap1 activity has anti-tumor effects in gastric tumors driven by oncogenic mutations and inflammatory cytokines. We show that Yap1 is a key regulator of cell metabolism, proliferation, and immune responses in normal and neoplastic gastric epithelium. We propose that the Hippo pathway is targetable across gastric cancer subtypes and its therapeutic benefits are likely to be mediated by both cancer cell-intrinsic and -extrinsic mechanisms.

Interleukin-11 and its eminent role in tissue fibrosis: a possible therapeutic target

Interleukin-11 is a cytokine from the IL-6 family of cytokines that includes IL-6 and oncostatin-M. Initially described for its role in platelet generation, it is now appreciated that this cytokine has multiple functions. Recently it has been found that IL-11 is critical in fibrosis in multiple different organ systems and systemically as in the autoimmune disease systemic sclerosis. Animal models of fibrosis have determined that animals with IL-11 receptor deletions have retarded fibrosis and that in wild-type animals IL-11 is found at the organ of fibrosis. Recent evidence suggests that IL-11 may be a master regulator of fibrosis regardless of end target organ. With the development of neutralizing antibodies targeting the cytokine in pre-clinical models this could be a possible therapeutic, in a disease in which no specific therapies exist. This review appraises the evidence of the role of IL-11 in tissue fibrosis, its signalling properties, and therapeutic targeting. The review ends with an appraisal of indications for which IL-11 modulation is targeted.

SARS-CoV-2 accessory proteins involvement in inflammatory and profibrotic processes through IL11 signaling

SARS-CoV-2, the cause of the COVID-19 pandemic, possesses eleven accessory proteins encoded in its genome. Their roles during infection are still not completely understood. In this study, transcriptomics analysis revealed that both WNT5A and IL11 were significantly up-regulated in A549 cells expressing individual accessory proteins ORF6, ORF8, ORF9b or ORF9c from SARS-CoV-2 (Wuhan-Hu-1 isolate). IL11 is a member of the IL6 family of cytokines. IL11 signaling-related genes were also differentially expressed. Bioinformatics analysis disclosed that both WNT5A and IL11 were involved in pulmonary fibrosis idiopathic disease and functional assays confirmed their association with profibrotic cell responses. Subsequently, data comparison with lung cell lines infected with SARS-CoV-2 or lung biopsies from patients with COVID-19, evidenced altered profibrotic gene expression that matched those obtained in this study. Our results show ORF6, ORF8, ORF9b and ORF9c involvement in inflammatory and profibrotic responses. Thus, these accessory proteins could be targeted by new therapies against COVID-19 disease.

Bazedoxifene attenuates intestinal injury in sepsis by suppressing the NF-κB/NLRP3 signaling pathways

Acute inflammatory injury is the primary cause of sepsis, leading to various organ failures. Bazedoxifene (BAZ) has been proven to have anti-inflammatory effects. However, its effects on sepsis-induced intestinal injury are unclear. Here, we demonstrated the beneficial effects of BAZ on intestinal injury and explored the underlying mechanisms using cecal ligation and perforation (CLP)-mediated sepsis mouse model and in vitro cultured intestinal epithelial MODE-K cells. We found that BAZ elevated the survival rate of septic mice and attenuated CLP-triggered intestinal damage. BAZ inhibited intestinal inflammation and restored the impaired intestinal barriers in CLP mice. The mechanistic study in lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-stimulated MODE-K cells showed that BAZ significantly downregulated the expression of NOD-like receptor protein 3 (NLRP3), interleukin-1β (IL-1β), caspase-1, and gasdermin D (GSDMD), and markedly reduced the phosphorylation of molecules in the nuclear factor kappa B (NF-κB) pathway. Moreover, BAZ prominently rescued the decreased viability of MODE-K cells and reduced lactate dehydrogenase (LDH) release upon LPS/ATP challenge. However, BAZ did not affect the inflammasome assembly, as evidenced by the lack of changes in ASC (apoptosis speck-like protein containing a CARD) speck formation. Our results suggest that BAZ relieves inflammation and intestinal barrier function disruption by suppressing the NF-κB/NLRP3 signaling pathways. Therefore, BAZ is a potential therapeutic candidate for treating intestinal injury in sepsis.

Vanillin-Based Indolin-2-one Derivative Bearing a Pyridyl Moiety as a Promising Anti-Breast Cancer Agent via Anti-Estrogenic Activity

The structure-based design introduced indoles as an essential motif in designing new selective estrogen receptor modulators employed for treating breast cancer. Therefore, here, a series of synthesized vanillin-substituted indolin-2-ones were screened against the NCI-60 cancer cell panel followed by in vivo, in vitro, and in silico studies. Physicochemical parameters were evaluated with HPLC and SwissADME tools. The compounds demonstrated promising anti-cancer activity for the MCF-7 breast cancer cell line (GI = 6-63%). The compound with the highest activity (6j) was selective for the MCF-7 breast cancer cell line (IC₅₀ = 17.01 μM) with no effect on the MCF-12A normal breast cell line supported by real-time cell analysis. A morphological examination of the used cell lines confirmed a cytostatic effect of compound 6j. It inhibited both in vivo and in vitro estrogenic activity, triggering a 38% reduction in uterine weight induced by estrogen in an immature rat model and hindering 62% of ER-α receptors in in vitro settings. In silico molecular docking and molecular dynamics simulation studies supported the stability of the ER-α and compound 6j protein-ligand complex. Herein, we report that indolin-2-one derivative 6j is a promising lead compound for further pharmaceutical formulations as a potential anti-breast cancer drug.

The Interleukin-11/IL-11 Receptor Promotes Glioblastoma Survival and Invasion under Glucose-Starved Conditions through Enhanced Glutaminolysis

Glioblastoma cells adapt to changes in glucose availability through metabolic plasticity allowing for cell survival and continued progression in low-glucose concentrations. However, the regulatory cytokine networks that govern the ability to survive in glucose-starved conditions are not fully defined. In the present study, we define a critical role for the IL-11/IL-11Rα signalling axis in glioblastoma survival, proliferation and invasion when cells are starved of glucose. We identified enhanced IL-11/IL-11Rα expression correlated with reduced overall survival in glioblastoma patients. Glioblastoma cell lines over-expressing IL-11Rα displayed greater survival, proliferation, migration and invasion in glucose-free conditions compared to their low-IL-11Rα-expressing counterparts, while knockdown of IL-11Rα reversed these pro-tumorigenic characteristics. In addition, these IL-11Rα-over-expressing cells displayed enhanced glutamine oxidation and glutamate production compared to their low-IL-11Rα-expressing counterparts, while knockdown of IL-11Rα or the pharmacological inhibition of several members of the glutaminolysis pathway resulted in reduced survival (enhanced apoptosis) and reduced migration and invasion. Furthermore, IL-11Rα expression in glioblastoma patient samples correlated with enhanced gene expression of the glutaminolysis pathway genes GLUD1, GSS and c-Myc. Overall, our study identified that the IL-11/IL-11Rα pathway promotes glioblastoma cell survival and enhances cell migration and invasion in environments of glucose starvation via glutaminolysis.

Repurposed Drugs in Gastric Cancer

Gastric cancer (GC) is one of the major causes of death worldwide, ranking as the fifth most incident cancer in 2020 and the fourth leading cause of cancer mortality. The majority of GC patients are in an advanced stage at the time of diagnosis, presenting a poor prognosis and outcome. Current GC treatment approaches involve endoscopic detection, gastrectomy and chemotherapy or chemoradiotherapy in an adjuvant or neoadjuvant setting. Drug development approaches demand extreme effort to identify molecular mechanisms of action of new drug candidates. Drug repurposing is based on the research of new therapeutic indications of drugs approved for other pathologies. In this review, we explore GC and the different drugs repurposed for this disease.

STAT3 Signaling in Breast Cancer: Multicellular Actions and Therapeutic Potential

Simple Summary

Many signaling pathways are overactive in breast cancer, and among them is the STAT3 signaling pathway. STAT3 is activated by secreted factors within the breast tumor, many of which are elevated and correlate to advanced disease and poor survival outcomes. This review examines how STAT3 signaling is activated in breast cancer by the proinflammatory, gp130 cytokines, interleukins 6 and 11. We evaluate how this signaling cascade functions in the various cells of the tumor microenvironment to drive disease progression and metastasis. We discuss how our understanding of these processes may lead to the development of novel therapeutics to tackle advanced disease.

Abstract

Interleukin (IL)-6 family cytokines, such as IL-6 and IL-11, are defined by the shared use of the gp130 receptor for the downstream activation of STAT3 signaling and the activation of genes which contribute to the “hallmarks of cancer”, including proliferation, survival, invasion and metastasis. Increased expression of these cytokines, or the ligand-specific receptors IL-6R and IL-11RA, in breast tumors positively correlate to disease progression and poorer patient outcome. In this review, we examine evidence from pre-clinical studies that correlate enhanced IL-6 and IL-11 mediated gp130/STAT3 signaling to the progression of breast cancer. Key processes by which the IL-6 family cytokines contribute to the heterogeneous nature of breast cancer, immune evasion and metastatic potential, are discussed. We examine the latest research into the therapeutic targeting of IL-6 family cytokines that inhibit STAT3 transcriptional activity as a potential breast cancer treatment, including current clinical trials. The importance of the IL-6 family of cytokines in cellular processes that promote the development and progression of breast cancer warrants further understanding of the molecular basis for its actions to help guide the development of future therapeutic targets.

Local and systemic effects of interleukin-6 (IL-6) in inflammation and cancer

Interleukin-6 (IL-6) is an inflammatory cytokine, the level of which is highly elevated in most, if not all, inflammatory states. IL-6 triggers cell type-specific responses and acts on target cells via a specific interleukin-6 receptor (IL-6R), which, together with IL-6, binds to and induces the dimerization of a second receptor subunit, gp130. IL-6 also binds to soluble IL-6R, and this complex interacts with gp130, regardless of IL-6R expression. This allows cells that do not express IL-6R and would be otherwise insensitive to IL-6 to respond to it. We have generated a constitutively active version of gp130 by forced leucine-zipper-mediated dimerization, named L-gp130. Once inserted into the Rosa26 locus of mice, L-gp130 can be activated in a cell-autonomous manner by crossing these mice with any Cre-recombinase transgenic mouse strain. Activation of gp130 in hepatocytes produced liver-specific effects such as the induction of acute-phase proteins, but it also had profound systemic effects on the immune system. Such local and systemic effects of interleukin-6 will be reviewed.

New insights into IL-6 family cytokines in metabolism, hepatology and gastroenterology

IL-6 family cytokines are defined by the common use of the signal-transducing receptor chain glycoprotein 130 (gp130). Increasing evidence indicates that these cytokines are essential in the regulation of metabolic homeostasis as well as in the pathophysiology of multiple gastrointestinal and liver disorders, thus making them attractive therapeutic targets. Over the past few years, therapies modulating gp130 signalling have grown exponentially in several clinical settings including obesity, cancer and inflammatory bowel disease. A newly engineered gp130 cytokine, IC7Fc, has shown promising preclinical results for the treatment of type 2 diabetes, obesity and liver steatosis. Moreover, drugs that modulate gp130 signalling have shown promise in refractory inflammatory bowel disease in clinical trials. A deeper understanding of the main roles of the IL-6 family of cytokines during homeostatic and pathological conditions, their signalling pathways, sources of production and target cells will be crucial to the development of improved treatments. Here, we review the current state of the role of these cytokines in hepatology and gastroenterology and discuss the progress achieved in translating therapeutics targeting gp130 signalling into clinical practice.

The IL6-like Cytokine Family: Role and Biomarker Potential in Breast Cancer

IL6-like cytokines are a family of regulators with a complex, pleiotropic role in both the healthy organism, where they regulate immunity and homeostasis, and in different diseases, including cancer. Here we summarise how these cytokines exert their effect through the shared signal transducer IL6ST (gp130) and we review the extensive evidence on the role that different members of this family play in breast cancer. Additionally, we discuss how the different cytokines, their related receptors and downstream effectors, as well as specific polymorphisms in these molecules, can serve as predictive or prognostic biomarkers with the potential for clinical application in breast cancer. Lastly, we also discuss how our increasing understanding of this complex signalling axis presents promising opportunities for the development or repurposing of therapeutic strategies against cancer and, specifically, breast neoplasms.

IL-6 in the Ecosystem of Head and Neck Cancer: Possible Therapeutic Perspectives

Interleukin-6 (IL-6) is a highly potent cytokine involved in multiple biological processes. It was previously reported to play a distinct role in inflammation, autoimmune and psychiatric disorders, ageing and various types of cancer. Furthermore, it is understood that IL-6 and its signaling pathways are substantial players in orchestrating the cancer microenvironment. Thus, they appear to be potential targets in anti-tumor therapy. The aim of this article is to elucidate the role of IL-6 in the tumor ecosystem and to review the possible therapeutic approaches in head and neck cancer.

The role of proteolysis in interleukin-11 signaling

Although interleukin-11 (IL-11) was discovered more than 30 years ago, it remains an understudied member of the IL-6 family of cytokines. While it was originally discovered as a secreted factor that could foster megakaryocyte maturation and was therefore used as a recombinant protein to increase platelet production in patients with thrombocytopenia, recent research has established important roles for IL-11 in inflammation, fibrosis and cancer. In order to initiate signal transduction, IL-11 binds first to a non-signaling membrane-bound IL-11 receptor (IL-11R, classic signaling), which subsequently induces the formation of a heterodimer of the signal-transducing receptor gp130 that is shared with the other family members. Complex formation initiates several intracellular signaling cascades, most notably the Janus kinase/Signal Transducer and Activator of Transcription (Jak/STAT) pathway. We have recently identified a trans-signaling mechanism, in which IL-11 binds to soluble forms of the IL-11R (sIL-11R) and the agonistic IL-11/sIL-11R complex can activate cells that do not express the IL-11R and would usually not respond to IL-11. The generation of sIL-11R and thus the initiation of IL-11 trans-signaling is mediated by proteolytic cleavage. In this review, we summarize the current state of knowledge regarding IL-11R cleavage, highlight recent developments in IL-11 biology and discuss therapeutic opportunities and challenges in the light of IL-11 classic and trans-signaling.

Estrogen Receptor Modulators in Viral Infections Such as SARS-CoV-2: Therapeutic Consequences

COVID-19 is a pandemic respiratory disease caused by the SARS-CoV-2 coronavirus. The worldwide epidemiologic data showed higher mortality in males compared to females, suggesting a hypothesis about the protective effect of estrogens against severe disease progression with the ultimate end being patient's death. This article summarizes the current knowledge regarding the potential effect of estrogens and other modulators of estrogen receptors on COVID-19. While estrogen receptor activation shows complex effects on the patient's organism, such as an influence on the cardiovascular/pulmonary/immune system which includes lower production of cytokines responsible for the cytokine storm, the receptor-independent effects directly inhibits viral replication. Furthermore, it inhibits the interaction of IL-6 with its receptor complex. Interestingly, in addition to natural hormones, phytestrogens and even synthetic molecules are able to interact with the estrogen receptor and exhibit some anti-COVID-19 activity. From this point of view, estrogen receptor modulators have the potential to be included in the anti-COVID-19 therapeutic arsenal.

Interleukin 11 (IL-11): Role(s) in Breast Cancer Bone Metastases

Bone metastases represent the main problem related to the progression of breast cancer, as they are the main cause of death for these patients. Unfortunately, to date, bone metastases are incurable and represent the main challenge for the researcher. Chemokines and cytokines affect different stages of the metastatic process, and in bone metastases, interleukin (IL) -6, IL-8, IL-1β, and IL-11 participate in the interaction between cancer cells and bone cells. This review focuses on IL-11, a pleiotropic cytokine that, in addition to its well-known effects on several tissues, also mediates certain signals in cancer cells. In particular, as IL-11 works on bone remodeling, it plays a relevant role in the osteolytic vicious cycle of bone resorption and tumour growth, which characterizes bone metastasis. IL-11 appears as a candidate for anti-metastatic therapy. Even if different therapeutic approaches have considered IL-11 and the downstream-activated gp130 signaling pathways activated downstream of gp130, further studies are needed to decipher the contribution of the different cytokines and their mechanisms of action in breast cancer progression to define therapeutic strategies.

gp130 blockade to NOD off Crohn's disease

In a recent publication, Nayar et al. uncover specific inflammatory cell populations associated with Crohn's disease (CD) pathogenesis, and a gp130-STAT3 signaling axis linked to disease in anti-TNF antibody treatment-refractory patients. Therefore, gp130 blockade might represent a potential CD therapy approach, perhaps in conjunction with existing anti-TNF treatment regimes.

Key biomarkers within the colorectal cancer related inflammatory microenvironment

Therapeutic approaches focused on the inflammatory microenvironment are currently gaining more support, as biomolecules involved in the inflammatory colorectal cancer (CRC) tumor microenvironment are being explored. We analyzed tumor and paired normal tissue samples from CRC patients (n = 22) whom underwent tumor resection surgery. We assessed 39 inflammation-involved biomolecules (multiplex magnetic bead-based immunoassay), CEA and CA19-9 (ELISA assay) and the tissue expression levels of occludin and also pErk, STAT1 and STAT3 transcriptional factors (western blot). Tumor staging has been established by histopathological evaluation of HE stained tumor tissue sections. We report 32 biomarkers displaying statistically significant differences in tumor vs. control. Additionally, positive statistical biomarker correlations were found between MMP2–IL8 and BAFF–IL8 (Pearson correlation coefficients > 0.751), while APRIL–MMP2, APRIL–BAFF and APRIL–IL8 were negatively correlated (correlation coefficients < − 0.650). While APRIL, BAFF, IL8 and MMP2 did not modulate with tumor stage, they were inversely related to the immune infiltrate level and CD163 tissue expression. We conclude that the significantly decreased APRIL and increased BAFF, IL8 and MMP2 expression were tumor-specific and deserve consideration in the development of new treatments. Also, the positive correlation between Chitinase 3-like 1 and IL8 (0.57) or MMP2 (0.50) suggest a role in tumor growth and metastasis pathways.

A myeloid-stromal niche and gp130 rescue in NOD2-driven Crohn's disease

Crohn's disease is a chronic inflammatory intestinal disease that is frequently accompanied by aberrant healing and stricturing complications. Crosstalk between activated myeloid and stromal cells is critical in the pathogenicity of Crohn's disease^1,2, and increases in intravasating monocytes are correlated with a lack of response to anti-TNF treatment³. The risk alleles with the highest effect on Crohn's disease are loss-of-function mutations in NOD2^4,5, which increase the risk of stricturing⁶. However, the mechanisms that underlie pathogenicity driven by NOD2 mutations and the pathways that might rescue a lack of response to anti-TNF treatment remain largely uncharacterized. Here we use direct ex vivo analyses of patients who carry risk alleles of NOD2 to show that loss of NOD2 leads to dysregulated homeostasis of activated fibroblasts and macrophages. CD14⁺ peripheral blood mononuclear cells from carriers of NOD2 risk alleles produce cells that express high levels of collagen, and elevation of conserved signatures is observed in nod2-deficient zebrafish models of intestinal injury. The enrichment of STAT3 regulation and gp130 ligands in activated fibroblasts and macrophages suggested that gp130 blockade might rescue the activated program in NOD2-deficient cells. We show that post-treatment induction of the STAT3 pathway is correlated with a lack of response to anti-TNF treatment in patients, and demonstrate in vivo in zebrafish the amelioration of the activated myeloid-stromal niche using the specific gp130 inhibitor bazedoxifene. Our results provide insights into NOD2-driven fibrosis in Crohn's disease, and suggest that gp130 blockade may benefit some patients with Crohn's disease-potentially as a complement to anti-TNF therapy.

A comprehensive review on anticancer mechanism of bazedoxifene

Cancer is counted as a second leading cause of death among nontransmissible diseases. Identification of novel anticancer drugs is therefore necessary for the effective treatment of cancer. Conventional drug discovery is time consuming and expensive process. Unlike conventional drug discovery, drug repositioning offers a novel strategy for urgent drug discovery since it is a cost-effective and faster process. Bazedoxifene (BZA) is a synthetic selective estrogen receptor modulator, approved by the United States Food and Drug Administration for the treatment of osteoporosis in postmenopausal women. BZA is now being studied for its anticancer activity in various cancers including breast cancer, liver cancer, pancreatic cancer, colon cancer, head and neck cancer, medulloblastoma, brain cancer, and gastrointestinal cancer. Studies have reported that BZA is effective in reducing cancer progression through multiple mechanisms. BZA could effectively inhibit STAT3, PI3K/AKT, and MAPK signaling pathways and induce apoptosis. In addition to its anticancer activity as monotherapy, BZA has been shown to enhance the chemotherapeutic efficacy of clinical drugs such as paclitaxel, cisplatin, palbociclib, and oxaliplatin in multiple neoplasms. This review mainly focused on the anticancer activity, cellular targets, and anticancer mechanism of BZA, which may help the further design and conduct of research and repositioning it for oncological clinic trials.

Raloxifene inhibits pancreatic adenocarcinoma growth by interfering with ERβ and IL-6/gp130/STAT3 signaling

PURPOSE

Currently, the exact role of estrogen receptor (ER) signaling in pancreatic cancer is unknown. Recently, we showed that expression of phosphorylated ERβ correlates with a poor prognosis in patients with pancreatic ductal adenocarcinoma (PDAC). Here, we hypothesized that raloxifene, a FDA-approved selective ER modulator (SERM), may suppress PDAC tumor growth by interfering with ERβ signaling. To test this hypothesis, we studied the impact of raloxifene on interleukin-6/glycoprotein-130/signal transducer and activator of transcription-3 (IL-6/gp130/STAT3) signaling.

METHODS

Human PDAC cell lines were exposed to raloxifene after which growth inhibition was assessed using a BrdU assay. ER knockdown was performed using siRNAs specific for ERα and ERβ. The effects of raloxifene on IL-6 expression and STAT3 phosphorylation in PDAC cells were assessed by ELISA and Western blotting, respectively. In addition, raloxifene was administered to an orthotopic PDAC tumor xenograft mouse model, after which tumor growth was monitored and immunohistochemistry was performed.

RESULTS

Raloxifene inhibited the in vitro growth of PDAC cells, and this effect was reversed by siRNA-mediated knockdown of ERβ, but not of ERα, indicating ER isotype-specific signaling. We also found that treatment with raloxifene inhibited the release of IL-6 and suppressed the phosphorylation of STAT3Y705 in PDAC cells. In vivo, we found that orthotopic PDAC tumor growth, lymph node and liver metastases as well as Ki-67 expression were reduced in mice treated with raloxifene.

CONCLUSIONS

Inhibition of ERβ and the IL-6/gp130/STAT3 signaling pathway by raloxifene leads to potent reduction of PDAC growth in vitro and in vivo. Our results suggest that ERβ signaling and IL-6/gp130 interaction may serve as promising drug targets for pancreatic cancer and that raloxifene may serve as an attractive therapeutic option for PDAC patients expressing the ERβ isotype.

Raloxifene and Bazedoxifene Could Be Promising Candidates for Preventing the COVID-19 Related Cytokine Storm, ARDS and Mortality

The FDA-approved drugs raloxifene and bazedoxifene could be among the best candidates to prevent mortality in severe COVID-19 patients. Raloxifene and bazedoxifene inhibit IL-6 signaling at therapeutic doses, suggesting they have the potential to prevent the cytokine storm, ARDS and mortality in severe COVID-19 patients, as is being shown with humanized antibodies blocking IL-6 signaling. In addition, raloxifene and bazedoxifene are selective estrogen receptor modulators with strong antiviral activity.

Tumour suppressor 15-hydroxyprostaglandin dehydrogenase induces differentiation in colon cancer via GLI1 inhibition

Inflammation is an established risk factor for colorectal cancer. We and others have shown that colorectal cancer patients with elevated cysteinyl leukotriene receptor 2 (CysLT₂R) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) levels exhibit good prognoses. However, both CysLT₂R and 15-PGDH, which act as tumour suppressors, are often suppressed in colorectal cancer. We previously reported that leukotriene C₄ (LTC₄)-induced differentiation in colon cancer via CysLT₂R signalling. Here, we investigated the involvement of Hedgehog (Hh)-GLI1 signalling, which is often hyperactivated in colorectal cancer. We found that the majority of colorectal cancer patients had high-GLI1 expression, which was negatively correlated with CysLT₂R, 15-PGDH, and Mucin-2 and overall survival compared with the low-GLI1 group. LTC₄-induced 15-PGDH downregulated both the mRNA and protein expression of GLI1 in a protein kinase A (PKA)-dependent manner. Interestingly, the LTC₄-induced increase in differentiation markers and reduction in Wnt targets remained unaltered in GLI1-knockdown cells. The restoration of GLI1 in 15-PGDH-knockdown cells did not ameliorate the LTC₄-induced effects, indicating the importance of both 15-PGDH and GLI1. LTC₄-mediated reduction in the DCLK1 and LGR5 stemness markers in colonospheres was abolished in cells lacking 15-PGDH or GLI1. Both DCLK1 and LGR5 were highly increased in tumour tissue compared with the matched controls. Reduced Mucin-2 levels were observed both in zebrafish xenografts with GLI1-knockdown cells and in the cysltr2^-/- colitis-associated colon cancer (CAC) mouse model. Furthermore, GLI1 expression was positively correlated with stemness and negatively correlated with differentiation in CRC patients when comparing tumour and mucosal tissues. In conclusion, restoring 15-PGDH expression via CysLT₂R activation might benefit colorectal cancer patients.

Structural Understanding of Interleukin 6 Family Cytokine Signaling and Targeted Therapies: Focus on Interleukin 11

Cytokines are small signaling proteins that have central roles in inflammation and cell survival. In the half-century since the discovery of the first cytokines, the interferons, over fifty cytokines have been identified. Amongst these is interleukin (IL)-6, the first and prototypical member of the IL-6 family of cytokines, nearly all of which utilize the common signaling receptor, gp130. In the last decade, there have been numerous advances in our understanding of the structural mechanisms of IL-6 family signaling, particularly for IL-6 itself. However, our understanding of the detailed structural mechanisms underlying signaling by most IL-6 family members remains limited. With the emergence of new roles for IL-6 family cytokines in disease and, in particular, roles of IL-11 in cardiovascular disease, lung disease, and cancer, there is an emerging need to develop therapeutics that can progress to clinical use. Here we outline our current knowledge of the structural mechanism of signaling by the IL-6 family of cytokines. We discuss how this knowledge allows us to understand the mechanism of action of currently available inhibitors targeting IL-6 family cytokine signaling, and most importantly how it allows for improved opportunities to pharmacologically disrupt cytokine signaling. We focus specifically on the need to develop and understand inhibitors that disrupt IL-11 signaling.

Role of Interleukin-6 in Lung Complications in Patients With COVID-19: Therapeutic Implications

COVID-19 is viral respiratory infection with frequently fatal lung complications in the elderly or in people with serious comorbidities. Lung destruction appears to be associated with a cytokine storm related to an increased level of interleukin-6 (IL6). Therapeutic targeting of the interleukin-6 signaling pathway can attenuate such a cytokine storm and can be beneficial for patients with COVID-19 in danger of pulmonary failure. This article demonstrates the importance of IL6 in progression of disease and the possibility of inhibition of IL6 signaling in COVID-19 therapy.

Estrogen downregulates gp130 expression in HUVECs by regulating ADAM10 and ADAM17 via the estrogen receptor

Glycoprotein130 (gp130) is an important signal transducer in the interleukin-6 (IL-6) trans-signaling pathway, which plays a crucial role in chronic inflammation in atherosclerosis. Studies suggest that estrogen can inhibit IL-6/gp130 signaling and reduce the risk of coronary artery disease, but the precise mechanism is unclear. The aim of this study was to investigate whether and how estrogen regulates gp130 in human umbilical vein endothelial cells (HUVECs). HUVECs were first treated with IL-6 and soluble IL-6 receptor (sIL-6R) to induce inflammation, then treated with estradiol. We then measured the expression of gp130, a disintegrin and metalloproteinase 10 (ADAM10) and 17 (ADAM17) by RT-PCR and western blot. Levels of soluble gp130 (sgp130) in the culture supernatant were measured by ELISA. We found that IL-6 and sIL-6R increased expression of gp130 protein and decreased levels of sgp130 protein, without affecting gp130 mRNA levels. Estradiol treatment reversed these effects in a concentration- and time-dependent manner. These effects were regulated by ADAM10 and ADAM17 via an estrogen receptor α/β-dependent mechanism. These results shed further light on the mechanism underlying the clinical effects of estrogen therapy in atherosclerosis and coronary artery disease.

Repurposing of drugs as STAT3 inhibitors for cancer therapy

Drug repurposing is a valuable approach in delivering new cancer therapeutics rapidly into the clinic. Existing safety and patient tolerability data for drugs already in clinical use represent an untapped resource in terms of identifying therapeutic agents for off-label protein targets. The multicellular effects of STAT3 mediated by a range of various upstream signaling pathways make it an attractive therapeutic target with utility in a range of diseases including cancer, and has led to the development of a variety of STAT3 inhibitors. Moreover, heightened STAT3 transcriptional activation in tumor cells and within the cells of the tumor microenvironment contribute to disease progression. Consequently, there are many STAT3 inhibitors in preclinical development or under evaluation in clinical trials for their therapeutic efficacy predominantly in inflammatory diseases and cancer. Despite these advances, many challenges remain in ultimately providing STAT3 inhibitors to patients as cancer treatments, highlighting the need not only for a better understanding of the mechanisms associated with STAT3 activation, but also how various pharmaceutical agents suppress STAT3 activity in various cancers. In this review we discuss the importance of STAT3-dependent functions in cancer, review the status of compounds designed as direct-acting STAT3 inhibitors, and describe some of the strategies for repurposing of drugs as STAT3 inhibitors for cancer therapy.