Growth-suppressive activity of raloxifene on liver cancer cells by targeting IL-6/GP130 signaling

Ironing Out the Mechanism of gp130 Signaling

gp130 functions as a shared signal-transducing subunit not only for interleukin (IL)-6 but also for eight other human cytokine receptor complexes. The IL-6 signaling pathway mediated through gp130 encompasses classical, trans, or cluster signaling, intricately regulated by a diverse array of modulators affecting IL-6, its receptor, and gp130. Currently, only a limited number of small molecule antagonists and agonists for gp130 are known. This review aims to comprehensively examine the current knowledge of these modulators and provide insights into their pharmacological properties, particularly in the context of cancer and other diseases. Notably, the prominent gp130 modulators SC144, bazedoxifene, and raloxifene are discussed in detail, with a specific focus on the discovery of SC144's iron-chelating properties. This adds a new dimension to the understanding of its pharmacological effects and therapeutic potential in conditions where iron homeostasis is significant. Our bioinformatic analysis of gp130 and genes related to iron homeostasis reveals insightful correlations, implicating the role of iron in the gp130 signaling pathway. Overall, this review contributes to the evolving understanding of gp130 modulation and its potential therapeutic applications in various disease contexts. SIGNIFICANCE STATEMENT: This perspective provides a timely and comprehensive analysis of advancements in gp130 signaling research, emphasizing the therapeutic implications of the currently available modulators. Bioinformatic analysis demonstrates potential interplay between gp130 and genes that regulate iron homeostasis, suggesting new therapeutic avenues. By combining original research findings with a broader discussion of gp130's therapeutic potential, this perspective significantly contributes to the field.

Exploring the potential of drug repurposing for liver diseases: A comprehensive study

Drug repurposing involves the investigation of existing drugs for new indications. It offers a great opportunity to quickly identify a new drug candidate at a lower cost than novel discovery and development. Despite the importance and potential role of drug repurposing, there is no specific definition that healthcare providers and the World Health Organization credit. Unfortunately, many similar and interchangeable concepts are being used in the literature, making it difficult to collect and analyze uniform data on repurposed drugs. This research was conducted based on understanding general criteria for drug repurposing, concentrating on liver diseases. Many drugs have been investigated for their effect on liver diseases even though they were originally approved (or on their way to being approved) for other diseases. Some of the hypotheses for drug repurposing were first captured from the literature and then processed further to test the hypothesis. Recently, with the revolution in bioinformatics techniques, scientists have started to use drug libraries and computer systems that can analyze hundreds of drugs to give a short list of candidates to be analyzed pharmacologically. However, this study revealed that drug repurposing is a potential aid that may help deal with liver diseases. It provides available or under-investigated drugs that could help treat hepatitis, liver cirrhosis, Wilson disease, liver cancer, and fatty liver. However, many further studies are needed to ensure the efficacy of these drugs on a large scale.

The gp130/STAT3-endoplasmic reticulum stress axis regulates hepatocyte necroptosis in acute liver injury

AIM

To investigate the effect of the gp130/STAT3-endoplasmic reticulum (ER) stress axis on hepatocyte necroptosis during acute liver injury.

METHODS

ER stress and liver injury in LO2 cells were induced with thapsigargin, and in BALB/c mice with tunicamycin and carbon tetrachloride (CCl4). Glycoprotein 130 (gp130) expression, the degrees of ER stress, and hepatocyte necroptosis were assessed.

RESULTS

ER stress significantly upregulated gp130 expression in LO2 cells and mouse livers. The silencing of activating transcription factor 6 (ATF6), but not of ATF4, increased hepatocyte necroptosis and mitigated gp130 expression in LO2 cells and mice. Gp130 silencing reduced the phosphorylation of CCl4-induced signal transducer and activator of transcription 3 (STAT3), and aggravated ER stress, necroptosis, and liver injury in mice.

CONCLUSION

ATF6/gp130/STAT3 signaling attenuates necroptosis in hepatocytes through the negative regulation of ER stress during liver injury. Hepatocyte ATF6/gp130/STAT3 signaling may be used as a therapeutic target in acute liver injury.

The gp130/STAT3-endoplasmic reticulum stress axis regulates hepatocyte necroptosis in acute liver injury

AIM

To investigate the effect of the gp130/STAT3-endoplasmic reticulum (ER) stress axis on hepatocyte necroptosis during acute liver injury.

METHODS

ER stress and liver injury in LO2 cells were induced with thapsigargin, and in BALB/c mice with tunicamycin and carbon tetrachloride (CCl4). Glycoprotein 130 (gp130) expression, the degrees of ER stress, and hepatocyte necroptosis were assessed.

RESULTS

ER stress significantly upregulated gp130 expression in LO2 cells and mouse livers. The silencing of activating transcription factor 6 (ATF6), but not of ATF4, increased hepatocyte necroptosis and mitigated gp130 expression in LO2 cells and mice. Gp130 silencing reduced the phosphorylation of CCl4-induced signal transducer and activator of transcription 3 (STAT3), and aggravated ER stress, necroptosis, and liver injury in mice.

CONCLUSION

ATF6/gp130/STAT3 signaling attenuates necroptosis in hepatocytes through the negative regulation of ER stress during liver injury. Hepatocyte ATF6/gp130/STAT3 signaling may be used as a therapeutic target in acute liver injury.

Current and novel approaches in the pharmacological treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignant tumours worldwide. The mortality-to-incidence ratio is up to 91.6% in many countries, representing the third leading cause of cancer-related deaths. Systemic drugs, including the multikinase inhibitors sorafenib and lenvatinib, are first-line drugs used in HCC treatment. Unfortunately, these therapies are ineffective in most cases due to late diagnosis and the development of tumour resistance. Thus, novel pharmacological alternatives are urgently needed. For instance, immune checkpoint inhibitors have provided new approaches targeting cells of the immune system. Furthermore, monoclonal antibodies against programmed cell death-1 have shown benefits in HCC patients. In addition, drug combinations, including first-line treatment and immunotherapy, as well as drug repurposing, are promising novel therapeutic alternatives. Here, we review the current and novel pharmacological approaches to fight HCC. Preclinical studies, as well as approved and ongoing clinical trials for liver cancer treatment, are discussed. The pharmacological opportunities analysed here should lead to significant improvement in HCC therapy.

Alleviation of Inflammation and Oxidative Stress in Pressure Overload-Induced Cardiac Remodeling and Heart Failure via IL-6/STAT3 Inhibition by Raloxifene

BACKGROUND

Inflammation and oxidative stress are involved in the initiation and progress of heart failure (HF). However, the role of the IL6/STAT3 pathway in the pressure overload-induced HF remains controversial.

METHODS AND RESULTS

Transverse aortic constriction (TAC) was used to induce pressure overload-HF in C57BL/6J mice. 18 mice were randomized into three groups (Sham, TAC, and TAC+raloxifene, n = 6, respectively). Echocardiographic and histological results showed that cardiac hypertrophy, fibrosis, and left ventricular dysfunction were manifested in mice after TAC treatment of eight weeks, with aggravation of macrophage infiltration and interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) expression in the myocardium. TAC (four and eight weeks) elevated the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) and prohibitin2 (PHB2) protein expression. Importantly, IL-6/gp130/STAT3 inhibition by raloxifene alleviated TAC-induced myocardial inflammation, cardiac remodeling, and dysfunction. In vitro, we demonstrated cellular hypertrophy with STAT3 activation and oxidative stress exacerbation could be elicited by IL-6 (25 ng/mL, 48 h) in H9c2 myoblasts. Sustained IL-6 stimulation increased intracellular reactive oxygen species, repressed mitochondrial membrane potential (MMP), decreased intracellular content of ATP, and led to decreased SOD activity, an increase in iNOS protein expression, and increased protein expression of Pink1, Parkin, and Bnip3 involving in mitophagy, all of which were reversed by raloxifene.

CONCLUSION

Inflammation and IL-6/STAT3 signaling were activated in TAC-induced HF in mice, while sustained IL-6 incubation elicited oxidative stress and mitophagy-related protein increase in H9c2 myoblasts, all of which were inhibited by raloxifene. These indicated IL-6/STAT3 signaling might be involved in the pathogenesis of myocardial hypertrophy and HF.

Bazedoxifene exhibits anti-inflammation and anti-atherosclerotic effects via inhibition of IL-6/IL-6R/STAT3 signaling

Atherosclerosis is regarded as chronic inflammatory disease. The IL-6/STAT3 pathway plays an important role in inflammation. We previously described a small-molecule compound, Bazedoxifene, which target IL-6/STAT3 pathway and has been approved for clinical use for osteoporosis in postmenopausal women. The aim of this study is to evaluate the effect of Bazedoxifene in the progression of atherosclerosis in apolipoprotein E-deficient (ApoE-/-) mice. Five-week-old male ApoE-/- mice were fed with High-fat diet (HFD) containing 5 mg/kg Bazedoxifene or a matching control for 12 weeks. Oil red O (ORO) staining was used to detect plaque size; immunohistochemical staining was used to detect the presence of endothelial cells, vascular muscle cells and phosphorylated STAT3 (P-STAT3) in localized plaques. The potential underlying mechanisms in human umbilical vein endothelial cells (HUVECs) and vascular muscle cells (VSMCs) was detected by Western blot analysis, Wound healing assay and Elisa assay. In the ApoE-/- mice fed with HFD, daily Bazedoxifene administration effectively attenuated atherosclerotic plaque area (P < 0.01), down-regulated IL-6 levels (P < 0.01), decreased STAT3 phosphorylation, reduced VSMCs proliferation and increased endothelial coverage in aortic vessels. Interestingly, we found HUVECs lack of membrane IL-6 receptor (IL-6R) compared to VSMCs (P < 0.01). Furthermore, we found that the soluble IL-6 receptor (sIL6R) participates in the activation of STAT3 induced by IL-6 or TNF-α in HUVECs and primary HUVECs. Bazedoxifene did not inhibit the growth of HUVECs while suppressing the proliferation of VSMCs. Bazedoxifene is an attractive novel therapeutic reagent for atherosclerosis diseases. This mechanism may be partially attributed to regulating IL-6/IL-6R/STAT3 signaling pathway.

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 inhibits IL-6/STAT3 signaling pathway and protects against high-fat-induced atherosclerosis in ApoE-/- mice

AIMS

The signal transducer and activator of transcription 3 (STAT3) pathway plays an important role in inflammatory cascade process. Our previous studies found that Raloxifene targeted against IL-6/GP130 protein-protein interface and inhibited STAT3 phosphorylation induced by IL-6 in cancer cells. However, whether Raloxifene could suppress IL-6/STAT3 signaling pathway and attenuate atherosclerosis in high-fat diet (HFD)-induced mice remains unknown. The objective of this study was to explore the potential effect of Raloxifene on the prevention of atherosclerosis.

MAIN METHODS

HFD-induced atherosclerosis was established in apoliprotein E-deficient (ApoE ^-/-) mice. Mice by daily intragastric gavage with Raloxifene or vehicle as controls were provided. The human umbilical vein endothelial cells (HUVEC), Rat VSMC and RAW264.7 cell lines were used to evaluate the effect of Raloxifene in vitro.

KEY FINDINGS

We demonstrated that Raloxifene was effective in ameliorating HFD- induced atherosclerosis plaque burden and size. Histological analysis showed that the expression of IL-6, P-STAT3, ICAM-1, VCAM-1, CD68 and α-SMA were significantly decreased in the Raloxifene intervention group compared to HFD group. Moreover, we observed that IL-6 increased migration and cell viability of VSMCs and RAW264.7 cells, while Raloxifene treatment decreased migration and reduced cell viability of VSMCs and RAW264.7 cells stimulated by IL-6. Furthermore, this effect was related to blocking IL-6/STAT3 pathway.

SIGNIFICANCE

Raloxifene has effects on inhibiting atherosclerosis development, the underlying mechanisms might involve in inhibiting inflammation-related IL-6/STAT3 signaling pathway.

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

Excessive signaling through gp130, the shared receptor for the interleukin (IL)6 family of cytokines, is a common hallmark in solid malignancies and promotes their progression. Here, we established the in vivo utility of bazedoxifene, a steroid analog clinically approved for the treatment of osteoporosis, to suppress gp130‐dependent tumor growth of the gastrointestinal epithelium. Bazedoxifene administration reduced gastric tumor burden in gp130^Y757F mice, where tumors arise exclusively through excessive gp130/STAT3 signaling in response to the IL6 family cytokine IL11. Likewise, in mouse models of sporadic colon and intestinal cancers, which arise from oncogenic mutations in the tumor suppressor gene Apc and the associated β‐catenin/canonical WNT pathway, bazedoxifene treatment reduces tumor burden. Consistent with the proposed orthogonal tumor‐promoting activity of IL11‐dependent gp130/STAT3 signaling, tumors of bazedoxifene‐treated Apc‐mutant mice retain excessive nuclear accumulation of β‐catenin and aberrant WNT pathway activation. Likewise, bazedoxifene treatment of human colon cancer cells harboring mutant APC did not reduce aberrant canonical WNT signaling, but suppressed IL11‐dependent STAT3 signaling. Our findings provide compelling proof of concept to support the repurposing of bazedoxifene for the treatment of gastrointestinal cancers in which IL11 plays a tumor‐promoting role.

Online structure-based screening of purchasable approved drugs and natural compounds: retrospective examples of drug repositioning on cancer targets

Drug discovery is a long and difficult process that benefits from the integration of virtual screening methods in experimental screening campaigns such as to generate testable hypotheses, accelerate and/or reduce the cost of drug development. Current drug attrition rate is still a major issue in all therapeutic areas and especially in the field of cancer. Drug repositioning as well as the screening of natural compounds constitute promising approaches to accelerate and improve the success rate of drug discovery. We developed three compounds libraries of purchasable compounds: Drugs-lib, FOOD-lib and NP-lib that contain approved drugs, food constituents and natural products, respectively, that are optimized for structure-based virtual screening studies. The three compounds libraries are implemented in the MTiOpenScreen web server that allows users to perform structure-based virtual screening computations on their selected protein targets. The server outputs a list of 1,500 molecules with predicted binding scores that can then be processed further by the users and purchased for experimental validation. To illustrate the potential of our service for drug repositioning endeavours, we selected five recently published drugs that have been repositioned in vitro and/or in vivo on cancer targets. For each drug, we used the MTiOpenScreen service to screen the Drugs-lib collection against the corresponding anti-cancer target and we show that our protocol is able to rank these drugs within the top ranked compounds. This web server should assist the discovery of promising molecules that could benefit patients, with faster development times, and reduced costs and risk.

IL-6 family cytokines: Key inflammatory mediators as biomarkers and potential therapeutic targets

IL-6 is a critical cytokine in acute phase response and involved in the pathogenesis of several chronic inflammatory diseases including cancer. Studies have highlighted that levels of IL-6 and its family members can be useful for diagnosis, prognosis of relapse-free survival and recurrence. IL-6 family cytokines have been identified as cancer biomarkers through screening of inflammatory mediators in different fluids including saliva, serum, and bronchoalveolar lavage fluid (BALF). IL-6 can be modulated by chemopreventive drugs, small molecules, monoclonal antibodies and immune checkpoint inhibitors. Unveiling the different sources of IL-6, the interaction between IL-6 and its cellular targets, the IL-6-dependent tumor resistance mechanisms, and the identification of novel regulators of IL-6 are some of the highly complex topics included in this review and their understanding could aid cancer biomarkers and therapy development.