Targeting STAT3 with silibinin to improve cancer therapeutics

Intelligent micelles for on-demand drug delivery targeting extracellular matrix of pancreatic cancer

As a key pathological feature of pancreatic ductal adenocarcinoma(PDAC), the dense extracellular matrix(ECM) limits the penetration of chemotherapy drugs and is involved in the formation of immunosuppressive microenvironment. Meanwhile, clinical practice has shown that the treatment strategy for ECM should consider its restriction of tumor cell metastasis, and the need for in-depth chemotherapy without destroying ECM is proposed. STAT3 inhibitors have been reported to regulate tumor microenvironment including interrupt the form of ECM. Therefore, we designed and established a micelle system MP@HA with in vivo targeting and responsive drug release function co-loading gemcitabine monophosphate and STAT3 inhibitor silibinin. The hyaluronic acid on the surface of the micelle can bind specifically to the CD44 molecule on the surface of tumor cells and help micelles accumulate at the tumor site. The nitroimidazole used to modify the polymeric skeleton can make the micellar structure collapse in response to hypoxia reduction conditions in the tumor environment, and release silibinin to widely regulate STAT3 molecules in the PDAC microenvironment. The polymer fragment attached with gemcitabine monophosphate can penetrate deep into PDAC tumors due to its small size and positive charge exposed, achieving deep chemotherapy. This research indicates a promising micelle system meeting complicated demands proposed in PDAC treatment to improve antitumor efficacy.

Inhibiting the Otub1/phosphorylated STAT3 axis for the treatment of non-small cell lung cancer

The transcription factor STAT3 is a promising target for the treatment of non-small cell lung cancer (NSCLC). STAT3 activity is mainly dependent on phosphorylation at tyrosine 705 (pSTAT3-Y705), but the modulation on pSTAT3-Y705 is elusive. By screening a library of deubiquitinases (Dubs), we found that the Otub1 increases STAT3 transcriptional activity. As a Dub, Otub1 binds to pSTAT3-Y705 and specifically abolishes its K48-linked ubiquitination, therefore preventing its degradation and promoting NSCLC cell survival. The Otub1/pSTAT3-Y705 axis could be a potential target for the treatment of NSCLC. To explore this concept, we screen libraries of FDA-approved drugs and natural products based on STAT3-recognition element-driven luciferase assay, from which crizotinib is found to block pSTAT3-Y705 deubiquitination and promotes its degradation. Different from its known action to induce ALK positive NSCLC cell apoptosis, crizotinib suppresses ALK-intact NSCLC cell proliferation and colony formation but not apoptosis. Furthermore, crizotinib also suppresses NSCLC xenograft growth in mice. Taken together, these findings identify Otub1 as the first deubiquitinase of pSTAT3-Y705 and provide that the Otub1/pSTAT3-Y705 axis is a promising target for the treatment of NSCLC.

Invasive growth of brain metastases is linked to CHI3L1 release from pSTAT3-positive astrocytes

BACKGROUND

Compared to minimally invasive brain metastases (MI BrM), highly invasive (HI) lesions form abundant contacts with cells in the peritumoral brain parenchyma and are associated with poor prognosis. Reactive astrocytes (RAs) labeled by phosphorylated STAT3 (pSTAT3) have recently emerged as a promising therapeutic target for BrM. Here, we explore whether the BrM invasion pattern is influenced by pSTAT3+ RAs and may serve as a predictive biomarker for STAT3 inhibition.

METHODS

We used immunohistochemistry to identify pSTAT3+ RAs in HI and MI human and patient-derived xenograft (PDX) BrM. Using PDX, syngeneic, and transgenic mouse models of HI and MI BrM, we assessed how pharmacological STAT3 inhibition or RA-specific STAT3 genetic ablation affected BrM growth in vivo. Cancer cell invasion was modeled in vitro using a brain slice-tumor co-culture assay. We performed single-cell RNA sequencing of human BrM and adjacent brain tissue.

RESULTS

RAs expressing pSTAT3 are situated at the brain-tumor interface and drive BrM invasive growth. HI BrM invasion pattern was associated with delayed growth in the context of STAT3 inhibition or genetic ablation. We demonstrate that pSTAT3+ RAs secrete Chitinase 3-like-1 (CHI3L1), which is a known STAT3 transcriptional target. Furthermore, single-cell RNA sequencing identified CHI3L1-expressing RAs in human HI BrM. STAT3 activation, or recombinant CHI3L1 alone, induced cancer cell invasion into the brain parenchyma using a brain slice-tumor plug co-culture assay.

CONCLUSIONS

Together, these data reveal that pSTAT3+ RA-derived CHI3L1 is associated with BrM invasion, implicating STAT3 and CHI3L1 as clinically relevant therapeutic targets for the treatment of HI BrM.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Natural products - Dawn of keloid treatment

Keloids are prevalent pathological scars, often leading to cosmetic deformities and hindering joint mobility.They cause discomfort, including burning and itching, while gradually expanding and potentially posing a risk of cancer.Developing effective drugs and treatments for keloids has been a persistent challenge in the medical field. Natural products are an important source of innovative drugs and a breakthrough for many knotty disease.Herein, keywords of "natural, plant, compound, extract" were combined with "keloid" and searched in PubMed and Google Scholar, respectively. A total of 32 natural products as well as 9 extracts possessing the potential for treating keloids were ultimately identified.Current research in this field faces a significant challenge due to the lack of suitable animal models, resulting in a predominant reliance on in vitro studies.In vivo and clinical studies are notably scarce as a result.Moreover, there is a notable deficiency in research focusing on the role of nutrients in keloid formation and treatment.The appropriate dosage form (oral, topical, injectable) is crucial for the development of natural product drugs. Finally, the conclusion was hereby made that natural products, when used as adjuncts to other treatments, hold significant potential in the management of keloids.By summarizing the natural products and elucidating their mechanisms in keloid treatment, the present study aims to stimulate further discoveries and research in drug development for effectively addressing this challenging condition.

Silibinin is a suppressor of the metastasis-promoting transcription factor ID3

BACKGROUND

ID3 (inhibitor of DNA binding/differentiation-3) is a transcription factor that enables metastasis by promoting stem cell-like properties in endothelial and tumor cells. The milk thistle flavonolignan silibinin is a phytochemical with anti-metastatic potential through largely unknown mechanisms.

HYPOTHESIS/PURPOSE

We have mechanistically investigated the ability of silibinin to inhibit the aberrant activation of ID3 in brain endothelium and non-small cell lung cancer (NSCLC) models.

METHODS

Bioinformatic analyses were performed to investigate the co-expression correlation between ID3 and bone morphogenic protein (BMP) ligands/BMP receptors (BMPRs) genes in NSCLC patient datasets. ID3 expression was assessed by immunoblotting and qRT-PCR. Luciferase reporter assays were used to evaluate the gene sequences targeted by silibinin to regulate ID3 transcription. In silico computational modeling and LanthaScreen TR-FRET kinase assays were used to characterize and validate the BMPR inhibitory activity of silibinin. Tumor tissues from NSCLC xenograft models treated with oral silibinin were used to evaluate the in vivo anti-ID3 effects of silibinin.

RESULTS

Analysis of lung cancer patient datasets revealed a top-ranked positive association of ID3 with the BMP9 endothelial receptor ACVRL1/ALK1 and the BMP ligand BMP6. Silibinin treatment blocked the BMP9-induced activation of the ALK1-phospho-SMAD1/5-ID3 axis in brain endothelial cells. Constitutive, acquired, and adaptive expression of ID3 in NSCLC cells were all significantly downregulated in response to silibinin. Silibinin blocked ID3 transcription via BMP-responsive elements in ID3 gene enhancers. Silibinin inhibited the kinase activities of BMPRs in the micromolar range, with the lower IC50 values occurring against ACVRL1/ALK1 and BMPR2. In an in vivo NSCLC xenograft model, tumoral overexpression of ID3 was completely suppressed by systematically achievable oral doses of silibinin.

CONCLUSIONS

ID3 is a largely undruggable metastasis-promoting transcription factor. Silibinin is a novel suppressor of ID3 that may be explored as a novel therapeutic approach to interfere with the metastatic dissemination capacity of NSCLC.

A comprehensive review of phytoconstituents in liver cancer prevention and treatment: targeting insights into molecular signaling pathways

Primary liver cancer is a type of cancer that develops in the liver. Hepatocellular carcinoma is a primary liver cancer that usually affects adults. Liver cancer is a fatal global condition that affects millions of people worldwide. Despite advances in technology, the mortality rate remains alarming. There is growing interest in researching alternative medicines to prevent or reduce the effects of liver cancer. Recent studies have shown growing interest in herbal products, nutraceuticals, and Chinese medicines as potential treatments for liver cancer. These substances contain unique bioactive compounds with anticancer properties. The causes of liver cancer and potential treatments are discussed in this review. This study reviews natural compounds, such as curcumin, resveratrol, green tea catechins, grape seed extracts, vitamin D, and selenium. Preclinical and clinical studies have shown that these medications reduce the risk of liver cancer through their antiviral, anti-inflammatory, antioxidant, anti-angiogenic, and antimetastatic properties. This article discusses the therapeutic properties of natural products, nutraceuticals, and Chinese compounds for the prevention and treatment of liver cancer.

The regulatory relationship between transcription factor STAT3 and noncoding RNA

Signal transducer and activator of transcription 3 (STAT3), as a key node in numerous carcinogenic signaling pathways, is activated in various tumor tissues and plays important roles in tumor formation, metastasis, and drug resistance. STAT3 is considered a potential subtarget for tumor therapy. Noncoding RNA (ncRNA) is a special type of RNA transcript. Transforming from "junk" transcripts into key molecules involved in cell apoptosis, growth, and functional regulation, ncRNA has been proven to be closely related to various epithelial-mesenchymal transition and drug resistance processes in tumor cells over the past few decades. Research on the relationship between transcription factor STAT3 and ncRNAs has attracted increased attention. To date, existing reviews have mainly focused on the regulation by ncRNAs on the transcription factor STAT3; there has been no review of the regulation by STAT3 on ncRNAs. However, understanding the regulation of ncRNAs by STAT3 and its mechanism is important to comprehensively understand the mutual regulatory relationship between STAT3 and ncRNAs. Therefore, in this review, we summarize the regulation by transcription factor STAT3 on long noncoding RNA, microRNA, and circular RNA and its possible mechanisms. In addition, we provide an update on research progress on the regulation of STAT3 by ncRNAs. This will provide a new perspective to comprehensively understand the regulatory relationship between transcription factor STAT3 and ncRNAs, as well as targeting STAT3 or ncRNAs to treat diseases such as tumors.

Silibinin Induces Both Apoptosis and Necroptosis with Potential Anti-tumor Efficacy in Lung Cancer

BACKGROUND

The incidence of lung cancer is steadily on the rise, posing a growing threat to human health. The search for therapeutic drugs from natural active substances and elucidating their mechanism have been the focus of anti-tumor research.

OBJECTIVE

Silibinin (SiL) has been shown to be a natural product with a wide range of pharmacological activities, including anti-tumour activity. In our work, SiL was chosen as a possible substance that could inhibit lung cancer. Moreover, its effects on inducing tumor cell death were also studied.

METHODS

CCK-8 analysis and morphological observation were used to assess the cytotoxic impacts of SiL on lung cancer cells in vitro. The alterations in mitochondrial membrane potential (MMP) and apoptosis rate of cells were detected by flow cytometry. The level of lactate dehydrogenase (LDH) release out of cells was measured. The expression changes of apoptosis or necroptosis-related proteins were detected using western blotting. Protein interactions among RIPK1, RIPK3, and MLKL were analyzed using the co-immunoprecipitation (co-IP) technique. Necrosulfonamide (Nec, an MLKL inhibitor) was used to carry out experiments to assess the changes in apoptosis following the blockade of cell necroptosis. in vitro, SiL was evaluated for its antitumor effects using LLC tumor-bearing mice with mouse lung cancer.

RESULTS

With an increased dose of SiL, the proliferation ability of A549 cells was considerably inhibited, and the accompanying cell morphology changed. The results of flow cytometry showed that after SiL treatment, MMP levels decreased, and the proportion of cells undergoing apoptosis increased. There was an increase in cleaved caspase-9, caspase-3, and PARP, with a down-regulation of Bcl-2 and an up-regulation of Bax. In addition, the amount of LDH released from the cells increased following SiL treatment, accompanied by augmented expression and phosphorylation levels of necroptosis-related proteins (MLKL, RIPK1, and RIPK3), and the co-IP assay further confirmed the interactions among these three proteins, indicating the necrosome formation induced by SiL. Furthermore, Nec increased the apoptotic rate of SiL-treated cells and aggravated the cytotoxic effect of SiL, indicating that necroptosis blockade could switch cell death to apoptosis and increase the inhibitory effect of SiL on A549 cells. In LLC-bearing mice, gastric administration of SiL significantly inhibited tumor growth, and H&E staining showed significant damage to the tumour tissue. The results of the IHC showed that the expression of RIPK1, RIPK3, and MLKL was more pronounced in the tumor tissue.

CONCLUSIONS

This study confirmed the dual effect of SiL, as it can induce both biological processes, apoptosis and necroptosis, in lung cancer. SiL-induced apoptosis involved the mitochondrial pathway, as indicated by changes in caspase-9, Bcl-2, and Bax. Necroptosis may be activated due to the changes in the expression of associated proteins in tumour cells and tissues. It has been observed that blocking necroptosis by SiL increased cell death efficiency. This study helps clarify the anti-tumor mechanism of SiL against lung cancer, elucidating its role in the dual induction of apoptosis and necroptosis. Our work provides an experimental basis for the research on cell death induced by SiL and reveals its possible applications for improving the management of lung cancer.

Harnessing immunotherapy for brain metastases: insights into tumor-brain microenvironment interactions and emerging treatment modalities

Brain metastases signify a deleterious milestone in the progression of several advanced cancers, predominantly originating from lung, breast and melanoma malignancies, with a median survival timeframe nearing six months. Existing therapeutic regimens yield suboptimal outcomes; however, burgeoning insights into the tumor microenvironment, particularly the immunosuppressive milieu engendered by tumor-brain interplay, posit immunotherapy as a promising avenue for ameliorating brain metastases. In this review, we meticulously delineate the research advancements concerning the microenvironment of brain metastases, striving to elucidate the panorama of their onset and evolution. We encapsulate three emergent immunotherapeutic strategies, namely immune checkpoint inhibition, chimeric antigen receptor (CAR) T cell transplantation and glial cell-targeted immunoenhancement. We underscore the imperative of aligning immunotherapy development with in-depth understanding of the tumor microenvironment and engendering innovative delivery platforms. Moreover, the integration with established or avant-garde physical methodologies and localized applications warrants consideration in the prevailing therapeutic schema.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Silibinin alleviates intestinal inflammation via inhibiting JNK signaling in Drosophila

Inflammatory bowel diseases (IBDs) are characterized by chronic relapsing intestinal inflammation that causes digestive system dysfunction. For years, researchers have been working to find more effective and safer therapeutic strategies to treat these diseases. Silibinin (SIL), a flavonoid compound extracted from the seeds of milk thistle plants, possesses multiple biological activities and is traditionally applied to treat liver diseases. SIL is also widely used in the treatment of a variety of inflammatory diseases attributed to its excellent antioxidant and anti-inflammatory effects. However, the efficacy of SIL against IBDs and its mechanisms remain unclear. In this study, using Drosophila melanogaster as a model organism, we found that SIL can effectively relieve intestinal inflammation caused by dextran sulfate sodium (DSS). Our results suggested that SIL supplementation can inhibit the overproliferation of intestinal stem cells (ISCs) induced by DSS, protect intestinal barrier function, acid-base balance, and intestinal excretion function, reduce intestinal reactive oxygen species (ROS) levels and inflammatory stress, and extend the lifespan of Drosophila. Furthermore, our study demonstrated that SIL ameliorates intestinal inflammation via modulating the c-Jun N-terminal kinase (JNK) signaling pathway in Drosophila. Our research aims to provide new insight into the treatment of IBDs.

Design, Synthesis and Biological Evaluation of Glycosylated Derivatives of Silibinin as Potential Anti-Tumor Agents

Objective

Silibinin, a natural product extracted from the seeds of the Silybum marianum, is versatile with various pharmacological effects. However, its clinical application was strongly hampered by its low bioavailability and poor water solubility. Herein, a series of glycosylated silibinin derivatives were identified as novel anti-tumor agents.

Materials and Methods

The cell viability was evaluated by CCK8 assay. Furthermore, cell apoptosis and cell cycle progression were tested by flow cytometry. In addition, the pharmacokinetic assessment of compound 15 and silibinin through intravenous administration (i.v., 2 mg/kg) to ICR mice were performed.

Results

The synthesized compounds showed better water solubilities than silibinin. Among them, compound 15 exhibited inhibitory activity against DU145 cells with IC₅₀ value of 1.37 ± 0.140 μM. Moreover, it arrested cell cycle at G2/M phase and induced apoptosis in DU145 cells. Additionally, compound 15 also displayed longer half-life (T_1/2 = 128.3 min) in liver microsomes than that of silibinin (T_1/2 = 82.5 min) and appropriate pharmacokinetic parameters in mice.

Conclusion

Overall, glycosylation of silibinin would be a valid strategy for the development of silibinin derivatives as anti-tumor agents.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Identification of CCR2 as a hub in septic myocardial injury and cardioprotection of silibinin

Myocardial injury is a serious complication of sepsis associated with high morbidity and mortality. Our previous work has confirmed that silibinin (SIL) alleviates septic myocardial injury, but the specific molecular mechanism has not been fully elucidated. This study aimed to identify its potential targets through network pharmacology combined with experimental verification. Firstly, a total of 29 overlapping genes between sepsis and SIL targets were obtained from RNA-seq analysis and the known databases. Subsequently, KEGG and GO analysis showed that these genes were enriched in immune response and cytokine-cytokine receptor interaction pathways. Notably, CCR2 was identified as an important candidate hub by protein-protein interaction analysis and molecular docking approach. In vivo experiments showed that SIL treatment significantly improved survival rate and cardiac function in septic mice, accompanied by decreased CCR2 expression. Moreover, in vitro experiments obtained the similar results. Especially, CCR2 siRNA attenuated inflammation response. In conclusion, this study systematically elucidated the key target of SIL in the treatment of septic myocardial injury. These findings provide valuable insights into the targets of sepsis and offer new avenues for exploring drug effect systematically.

Role of Plant-Derived Flavonoids in Cancer Treatment

Flavonoids are polyphenolic phytochemicals, which occur naturally in plants and possess both anti-oxidant and pro-oxidant properties. Flavonoids are gaining increasing popularity in the pharmaceutical industry as healthy and cost-effective compounds. Flavonoids show beneficial pharmacological activities in the treatment and prevention of various types of diseases. They are natural and less toxic agents for cancer chemotherapy and radiotherapy via regulation of multiple cell signaling pathways and pro-oxidant effects. In this review, we have summarized the mechanisms of action of selected flavonoids, and their pharmacological implications and potential therapeutic applications in cancer therapy.

PITX1 suppresses osteosarcoma metastasis through exosomal LINC00662-mediated M2 macrophage polarization

Paired-like homeodomain transcription factor 1 (PITX1) is frequently downregulated in cancers, including osteosarcoma (OS). However, its role in OS remains unknown. Therefore, we aimed to explore the functions and potential mechanisms of PITX1 in OS malignant progression. Elevated PITX1 suppressed OS cell proliferation and migration, based on transwell, proliferation, and colony formation assays. Pathway enrichment analysis of differentially-expressed genes between PITX1-overexpressing and control OS cells indicated that PITX1 expression was associated with the FAK/Src and PI3k/Akt signaling pathways. Mechanistically, ubiquitination assays and rescue experiments showed that PITX1 interacted with transcription factor STAT3, leading to decreased STAT3 transcriptional activity, which repressed the expression of LINC00662. Specific knockdown of LINC00662 reduced the tumor growth and invasion of OS cells induced by downregulated PITX1. Moreover, exosomal LINC00662, derived from PITX1 knockdown OS cell lines activated M2 macrophages in cell co-culture assays. M2 macrophage secreted several cytokines, among which CCL22 was found to cause OS cell EMT. Collectively, our data indicate that PITX1 suppresses OS cell proliferation and metastasis by downregulating LINC00662. Moreover, LINC00662 can be packaged into OS cell-derived exosomes to mediate M2 macrophage polarization to promote OS metastasis via CCL22.

Phytochemical Profiles and Biological Studies of Selected Botanical Dietary Supplements Used in the United States

Based on their current wide bioavailability, botanical dietary supplements have become an important component of the United States healthcare system, although most of these products have limited scientific evidence for their use. The most recent American Botanical Council Market Report estimated for 2020 a 17.3% increase in sales of these products when compared to 2019, for a total sales volume of $11,261 billion. The use of botanical dietary supplements products in the United States is guided by the Dietary Supplement Health and Education Act (DSHEA) from 1994, enacted by the U.S. Congress with the aim of providing more information to consumers and to facilitate access to a larger number of botanical dietary supplements available on the market than previously. Botanical dietary supplements may be formulated for and use only using crude plant samples (e.g., plant parts such as the bark, leaves, or roots) that can be processed by grinding into a dried powder. Plant parts can also be extracted with hot water to form an "herbal tea." Other preparations of botanical dietary supplements include capsules, essential oils, gummies, powders, tablets, and tinctures. Overall, botanical dietary supplements contain bioactive secondary metabolites with diverse chemotypes that typically are found at low concentration levels. These bioactive constituents usually occur in combination with inactive molecules that may induce synergy and potentiation of the effects observed when botanical dietary supplements are taken in their different forms. Most of the botanical dietary supplements available on the U.S. market have been used previously as herbal remedies or as part of traditional medicine systems from around the world. Their prior use in these systems also provides a certain level of assurance in regard to lower toxicity levels. This chapter will focus on the importance and diversity of the chemical features of bioactive secondary metabolites found in botanical dietary supplements that are responsible for their applications. Many of the active principles of botanical dietary substances are phenolics and isoprenoids, but glycosides and some alkaloids are also present. Biological studies on the active constituents of selected botanical dietary supplements will be discussed. Thus, the present chapter should be of interest for both members of the natural products scientific community, who may be performing development studies of the products available, as well as for healthcare professionals who are directly involved in the analysis of botanical interactions and evaluation of the suitability of botanical dietary supplements for human consumption.

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.

JAK/STAT pathway: Extracellular signals, diseases, immunity, and therapeutic regimens

Janus kinase/signal transduction and transcription activation (JAK/STAT) pathways were originally thought to be intracellular signaling pathways that mediate cytokine signals in mammals. Existing studies show that the JAK/STAT pathway regulates the downstream signaling of numerous membrane proteins such as such as G-protein-associated receptors, integrins and so on. Mounting evidence shows that the JAK/STAT pathways play an important role in human disease pathology and pharmacological mechanism. The JAK/STAT pathways are related to aspects of all aspects of the immune system function, such as fighting infection, maintaining immune tolerance, strengthening barrier function, and cancer prevention, which are all important factors involved in immune response. In addition, the JAK/STAT pathways play an important role in extracellular mechanistic signaling and might be an important mediator of mechanistic signals that influence disease progression, immune environment. Therefore, it is important to understand the mechanism of the JAK/STAT pathways, which provides ideas for us to design more drugs targeting diseases based on the JAK/STAT pathway. In this review, we discuss the role of the JAK/STAT pathway in mechanistic signaling, disease progression, immune environment, and therapeutic targets.

Silibinin Overcomes EMT-Driven Lung Cancer Resistance to New-Generation ALK Inhibitors

Epithelial-to-mesenchymal transition (EMT) may drive the escape of ALK-rearranged non-small-cell lung cancer (NSCLC) tumors from ALK-tyrosine kinase inhibitors (TKIs). We investigated whether first-generation ALK-TKI therapy-induced EMT promotes cross-resistance to new-generation ALK-TKIs and whether this could be circumvented by the flavonolignan silibinin, an EMT inhibitor. ALK-rearranged NSCLC cells acquiring a bona fide EMT phenotype upon chronic exposure to the first-generation ALK-TKI crizotinib exhibited increased resistance to second-generation brigatinib and were fully refractory to third-generation lorlatinib. Such cross-resistance to new-generation ALK-TKIs, which was partially recapitulated upon chronic TGFβ stimulation, was less pronounced in ALK-rearranged NSCLC cells solely acquiring a partial/hybrid E/M transition state. Silibinin overcame EMT-induced resistance to brigatinib and lorlatinib and restored their efficacy involving the transforming growth factor-beta (TGFβ)/SMAD signaling pathway. Silibinin deactivated TGFβ-regulated SMAD2/3 phosphorylation and suppressed the transcriptional activation of genes under the control of SMAD binding elements. Computational modeling studies and kinase binding assays predicted a targeted inhibitory binding of silibinin to the ATP-binding pocket of TGFβ type-1 receptor 1 (TGFBR1) and TGFBR2 but solely at the two-digit micromolar range. A secretome profiling confirmed the ability of silibinin to normalize the augmented release of TGFβ into the extracellular fluid of ALK-TKIs-resistant NSCLC cells and reduce constitutive and inducible SMAD2/3 phosphorylation occurring in the presence of ALK-TKIs. In summary, the ab initio plasticity along the EMT spectrum may explain the propensity of ALK-rearranged NSCLC cells to acquire resistance to new-generation ALK-TKIs, a phenomenon that could be abrogated by the silibinin-driven attenuation of the TGFβ/SMAD signaling axis in mesenchymal ALK-rearranged NSCLC cells.

Inhibition of STAT3 reverses Taxol-resistance in ovarian cancer by down-regulating G6PD expression in vitro

Ovarian cancer is the eminent gynecological malignancy and chemoresistance remains a major reason for poor in ovarian cancer patients. Taxol has been proved as the most effective chemotherapeutic agent against ovarian cancer. However development of Taxol resistance remains a major problem. Here, we report that STAT3, directly activates pentose-phosphate pathway to exert pro-oncogenic effects on Taxol resistance of ovarian cancer. In addition, we found that STAT3, p-STAT3 and glucose-6-phosphate dehydrogenase (G6PD) protein levels are upregulated in Taxol resistant cell lines compared with Taxol sensitive cell lines. Furthermore, inhibition of STAT3 decreased G6PD mRNA expression level and enhanced the sensitivity of Taxol resistant cell to Taxol. Finally, we found that STAT3 directly binds to the G6PD promoter region and promotes the expression of G6PD at transcriptional level. Taken together, our data indicate that activation of STAT3 promotes ovarian cancer cell proliferation, colony formation, and Taxol resistance via augmenting G6PD expression and pentose-phosphate metabolism flux, which provides a potential therapeutic target that may improve prognosis by decreasing G6PD expression and enhancing Taxol-sensitivity.

Mechanistic Insights into the Pharmacological Significance of Silymarin

Medicinal plants are considered the reservoir of diverse therapeutic agents and have been traditionally employed worldwide to heal various ailments for several decades. Silymarin is a plant-derived mixture of polyphenolic flavonoids originating from the fruits and akenes of Silybum marianum and contains three flavonolignans, silibinins (silybins), silychristin and silydianin, along with taxifolin. Silybins are the major constituents in silymarin with almost 70–80% abundance and are accountable for most of the observed therapeutic activity. Silymarin has also been acknowledged from the ancient period and is utilized in European and Asian systems of traditional medicine for treating various liver disorders. The contemporary literature reveals that silymarin is employed significantly as a neuroprotective, hepatoprotective, cardioprotective, antioxidant, anti-cancer, anti-diabetic, anti-viral, anti-hypertensive, immunomodulator, anti-inflammatory, photoprotective and detoxification agent by targeting various cellular and molecular pathways, including MAPK, mTOR, β-catenin and Akt, different receptors and growth factors, as well as inhibiting numerous enzymes and the gene expression of several apoptotic proteins and inflammatory cytokines. Therefore, the current review aims to recapitulate and update the existing knowledge regarding the pharmacological potential of silymarin as evidenced by vast cellular, animal, and clinical studies, with a particular emphasis on its mechanisms of action.

Inhibiting STAT3 signaling pathway by natural products for cancer prevention and therapy: In vitro and in vivo activity and mechanisms of action

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in signal transmission from the plasma membrane to the nucleus, regulating the expression of genes involved in essential cell functions and controlling the processes of cell cycle progression and apoptosis. Thus, STAT3 has been elucidated as a promising target for developing anticancer drugs. Many natural products have been reported to inhibit the STAT3 signaling pathway during the past two decades and have exhibited significant anticancer activities in vitro and in vivo. However, there is no FDA-approved STAT3 inhibitor yet. The major mechanisms of these natural product inhibitors of the STAT3 signaling pathway include targeting the upstream regulators of STAT3, directly binding to the STAT3 SH2 domain and inhibiting its activation, inhibiting STAT3 phosphorylation and/or dimerization, and others. In the present review, we have systematically discussed the development of these natural product inhibitors of STAT3 signaling pathway as well as their in vitro and in vivo anticancer activity and mechanisms of action. Outlooks and perspectives on the associated challenges are provided as well.

Suppressive Effects of Siegesbeckia orientalis Ethanolic Extract on Proliferation and Migration of Hepatocellular Carcinoma Cells through Promoting Oxidative Stress, Apoptosis and Inflammatory Responses

Previous studies have demonstrated that Siegesbeckia orientalis (SO) has a suppressive effect on the growth and migration of endometrial and cervical cancer cells. The present study examined the effect of SO ethanolic extract (SOE) on the proliferation and migration of hepatocellular carcinoma (HCC) and examined the effects of SOE on non-cancerous cells using HaCaT keratinocytes as a model. The SOE effectively inhibited the proliferation of Hepa1-6 (IC₅₀ = 282.4 μg/mL) and HepG2 (IC₅₀ = 344.3 μg/mL) hepatoma cells, whereas it has less cytotoxic effect on HaCaT cells (IC₅₀ = 892.4 μg/mL). The SOE treatment increased the generation of ROS in HCC, but decreased the expression of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and catalase. In contrast, it reduced intracellular ROS formation and upregulated the expression of the related antioxidant enzymes in the H₂O₂-stimulated HaCaT cells. The SOE intervention also down-regulated the anti-apoptotic Bcl-2 and the migration-related proteins including matrix metalloproteinases (MMPs) and β-catenin in the HCC, suggesting that SOE could promote HCC apoptosis and inhibit HCC migration. On the contrary, it reduced apoptosis and promoted the migration of the keratinocytes. Additionally, the SOE treatment significantly up-regulated the pro-inflammatory cytokines, including TNF-α, IL-6 and IL-1β, in Hepa1-6 and HepG2 cells. Conversely, it significantly decreased the expression of these cytokines in the H₂O₂-induced HaCaT cells. These findings indicated that SOE treatment can delay the progression of HCC by increasing oxidative stress, promoting inflammatory response, inducing cancer cell apoptosis and inhibiting their migration. It also has protective effects from pro-oxidant H₂O₂ in non-cancerous cells. Therefore, SOE may provide a potential treatment for liver cancer.

STAT3 pathway in cancers: Past, present, and future

Signal transducer and activator of transcription 3 (STAT3), a member of the STAT family, discovered in the cytoplasm of almost all types of mammalian cells, plays a significant role in biological functions. The duration of STAT3 activation in normal tissues is a transient event and is strictly regulated. However, in cancer tissues, STAT3 is activated in an aberrant manner and is induced by certain cytokines. The continuous activation of STAT3 regulates the expression of downstream proteins associated with the formation, progression, and metastasis of cancers. Thus, elucidating the mechanisms of STAT3 regulation and designing inhibitors targeting the STAT3 pathway are considered promising strategies for cancer treatment. This review aims to introduce the history, research advances, and prospects concerning the STAT3 pathway in cancer. We review the mechanisms of STAT3 pathway regulation and the consequent cancer hallmarks associated with tumor biology that are induced by the STAT3 pathway. Moreover, we summarize the emerging development of inhibitors that target the STAT3 pathway and novel drug delivery systems for delivering these inhibitors. The barriers against targeting the STAT3 pathway, the focus of future research on promising targets in the STAT3 pathway, and our perspective on the overall utility of STAT3 pathway inhibitors in cancer treatment are also discussed.

Silibinin Therapy Improves Cholangiocarcinoma Outcomes by Regulating ERK/Mitochondrial Pathway

Background: Silibinin is widely utilized drug in various cancer treatments, though its application in cholangiocarcinoma has not yet been explored. For the first time, we evaluated the anticancer potential and underlying molecular mechanism of silibinin in treatment of cholangiocarcinoma treatment.

Methods: HuCCT-1 and CCLP-1 cells were chosen to be an in vitro study model and were exposed to various concentrations of silibinin for indicated times. Cell viability was evaluated by the cell counting kit-8 (CCK-8) assay and half maximal inhibitory (IC50) concentrations were calculated. Cell proliferation capacity was determined through the use of colony formation and 5-Ethynyl-2′- deoxyuridine (EdU) assays. Cell apoptosis and cycle arrest were assessed by Live/Dead staining assay and flow cytometry (FCM). The protein levels of extracellular regulated protein kinases (ERK)/mitochondrial apoptotic pathway were evaluated through western blotting (WB). Mitochondrial membrane potential changes were determined via 5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide (JC-1). A cholangiocarcinoma cell line xenograft model was used to assess the anti-tumor activity of silibinin in vivo.

Results: Inhibition of the ERK protein by silibinin led to a significant decrease in mitochondrial membrane potential, which, in turn, caused Cytochrome C to be released from the mitochondria. The activation of downstream apoptotic pathways led to apoptosis of cholangiocarcinoma cells. In general, silibinin inhibited the growth of cholangiocarcinoma cell line xenograft tumors.

Conclusions: Silibinin is able to inhibit cholangiocarcinoma through the ERK/mitochondrial apoptotic pathway, which makes silibinin a potential anti-tumor drug candidate for cholangiocarcinoma treatment.

MicroRNA let-7 and viral infections: focus on mechanisms of action

MicroRNAs (miRNAs) are fundamental post-transcriptional modulators of several critical cellular processes, a number of which are involved in host defense mechanisms. In particular, miRNA let-7 functions as an essential regulator of the function and differentiation of both innate and adaptive immune cells. Let-7 is involved in several human diseases, including cancer and viral infections. Several viral infections have found ways to dysregulate the expression of miRNAs. Extracellular vesicles (EV) are membrane-bound lipid structures released from many types of human cells that can transport proteins, lipids, mRNAs, and miRNAs, including let-7. After their release, EVs are taken up by the recipient cells and their contents released into the cytoplasm. Let-7-loaded EVs have been suggested to affect cellular pathways and biological targets in the recipient cells, and can modulate viral replication, the host antiviral response, and the action of cancer-related viruses. In the present review, we summarize the available knowledge concerning the expression of let-7 family members, functions, target genes, and mechanistic involvement in viral pathogenesis and host defense. This may provide insight into the development of new therapeutic strategies to manage viral infections.

Role of Silymarin in Cancer Treatment: Facts, Hypotheses, and Questions

The flavonoid silymarin extracted from the seeds of Sylibum marianum is a mixture of 6 flavolignan isomers. The 3 more important isomers are silybin (or silibinin), silydianin, and silychristin. Silybin is functionally the most active of these compounds. This group of flavonoids has been extensively studied and they have been used as hepato-protective substances for the mushroom Amanita phalloides intoxication and mainly chronic liver diseases such as alcoholic cirrhosis and nonalcoholic fatty liver. Hepatitis C progression is not, or slightly, modified by silymarin. Recently, it has also been proposed for SARS COVID-19 infection therapy. The biochemical and molecular mechanisms of action of these substances in cancer are subjects of ongoing research. Paradoxically, many of its identified actions such as antioxidant, promoter of ribosomal synthesis, and mitochondrial membrane stabilization, may seem protumoral at first sight, however, silymarin compounds have clear anticancer effects. Some of them are: decreasing migration through multiple targeting, decreasing hypoxia inducible factor-1α expression, inducing apoptosis in some malignant cells, and inhibiting promitotic signaling among others. Interestingly, the antitumoral activity of silymarin compounds is limited to malignant cells while the nonmalignant cells seem not to be affected. Furthermore, there is a long history of silymarin use in human diseases without toxicity after prolonged administration. The ample distribution and easy accessibility to milk thistle-the source of silymarin compounds, its over the counter availability, the fact that it is a weed, some controversial issues regarding bioavailability, and being a nutraceutical rather than a drug, has somehow led medical professionals to view its anticancer effects with skepticism. This is a fundamental reason why it never achieved bedside status in cancer treatment. However, in spite of all the antitumoral effects, silymarin actually has dual effects and in some cases such as pancreatic cancer it can promote stemness. This review deals with recent investigations to elucidate the molecular actions of this flavonoid in cancer, and to consider the possibility of repurposing it. Particular attention is dedicated to silymarin's dual role in cancer and to some controversies of its real effectiveness.

Clinical Management of COVID-19 in Cancer Patients with the STAT3 Inhibitor Silibinin

COVID-19 pathophysiology is caused by a cascade of respiratory and multiorgan failures arising, at least in part, from the SARS-CoV-2-driven dysregulation of the master transcriptional factor STAT3. Pharmacological correction of STAT3 over-stimulation, which is at the root of acute respiratory distress syndrome (ARDS) and coagulopathy/thrombosis events, should be considered for treatment of severe COVID-19. In this perspective, we first review the current body of knowledge on the role of STAT3 in the pathogenesis of severe COVID-19. We then exemplify the potential clinical value of treating COVID-19 disease with STAT3 inhibitors by presenting the outcomes of two hospitalized patients with active cancer and COVID-19 receiving oral Legalon®-a nutraceutical containing the naturally occurring STAT3 inhibitor silibinin. Both patients, which were recruited to the clinical trial SIL-COVID19 (EudraCT number: 2020-001794-77) had SARS-CoV-2 bilateral interstitial pneumonia and a high COVID-GRAM score, and showed systemic proinflammatory responses in terms of lymphocytopenia and hypoalbuminemia. Both patients were predicted to be at high risk of critical COVID-19 illness in terms of intensive care unit admission, invasive ventilation, or death. In addition to physician's choice of best available therapy or supportive care, patients received 1050 mg/day Legalon® for 10 days without side-effects. Silibinin-treated cancer/COVID-19+ patients required only minimal oxygen support (2-4 L/min) during the episode, exhibited a sharp decline of the STAT3-regulated C-reactive protein, and demonstrated complete resolution of the pulmonary lesions. These findings might inspire future research to advance our knowledge and improve silibinin-based clinical interventions aimed to target STAT3-driven COVID-19 pathophysiology.

Glaucocalyxin A suppresses multiple myeloma progression in vitro and in vivo through inhibiting the activation of STAT3 signaling pathway

Background

Multiple myeloma (MM) is the most common malignant hematological disease in the people worldwide. Glaucocalyxin A (GLA) is a bioactive ent-kauranoid diterpenoid, that is derived from Rabdosia japonica var. GLA has been demonstrated that it had various pharmacological activities, such as anti-coagulation, anti-bacterial, anti-tumor, anti-inflammation, antioxidant activities. Although GLA has effective anti-tumor properties, its effects on multiple myeloma remain unclear. The aim of this study was to examine the possible anti-cancer effects of GLA and their molecular mechanisms on MM cells in vitro and in vivo.

Methods

To evaluate the role of GLA on the proliferation of MM cells in vitro and in vivo, we used MTT method to detect the role of GLA on the proliferation of MM cells. Cell apoptosis and cell cycle assay were evaluated by flow cytometry. Protein expressions in GLA-treated and untreated MM cells were evaluated by western blot analyses. MM xenograft nude mice model was used to investigate the role of GLA on the proliferation of MM cells in vivo. IHC assay was used to examine the role of GLA on the MM xenograft model in vivo.

Results

In the present study, we firstly reported the potent anti-myeloma activity of GLA on MM cells. We found that GLA could induce apoptosis in vitro and in vivo. GLA could inhibit the phosphorylation of the signal transducer and activator of transcription 3 (STAT3) and downregulate interleukin IL-6 induced STAT3 phosphorylation in MM. Overexpression of STAT3 could significantly prevent apoptosis induced by GLA; while knockdown of STAT3 enhanced it. Moreover, GLA could inhibit cell proliferation by inducing the cell cycle arrest. GLA reduced the expression of cell cycle-related proteins CCNB1, CCND1, CCND2, and CCND3 and increased the expression of p21 in MM cell lines. In addition, in the MM xenograft nude mice model, GLA exhibited very good anti-myeloma activity. Administration of GLA almost completely inhibited tumor growth within 19 days without physical toxicity. And the IHC results showed GLA significantly inhibited cell proliferation and interfered STAT3 pathway on MM xenograft model tumor tissues.

Conclusions

Taken together, our present research indicated that GLA inhibits the MM cell proliferation, induces MM cell apoptosis and cell cycle arrest through blocking the activation of STAT3 pathway. Thus, GLA may be a potential therapeutic candidate for MM patients in the future.

SPHK1 contributes to cisplatin resistance in bladder cancer cells via the NONO/STAT3 axis

Sphingosine-1-phosphate (S1P) serves an important role in various physiological and pathophysiological processes, including the regulation of cell apoptosis, proliferation and survival. Sphingosine kinase 1 (SPHK1) is a lipid kinase that phosphorylates sphingosine to generate S1P. S1P has been proven to be positively correlated with chemotherapy resistance in breast cancer, colorectal carcinoma and non-small cell lung cancer. However, whether SPHK1 is involved in the development of cisplatin resistance remains to be elucidated. The present study aimed to identify the association between SPHK1 and chemoresistance in bladder cancer cells and to explore the therapeutic implications in patients with bladder cancer. Bladder cancer cell proliferation and apoptosis were determined using Cell Counting Kit-8 assays and flow cytometry, respectively. Apoptosis-related proteins were detected via western blotting. The results revealed that SPHK1 was positively correlated with cisplatin resistance in bladder cancer cells, exhibiting an antiapoptotic effect that was reflected by the downregulation of apoptosis-related proteins (Bax and cleaved caspase-3) and the upregulation of an antiapoptotic protein (Bcl-2) in SPHK1-overexpression cell lines. Suppression of SPHK1 by small interfering RNA or FTY-720 significantly reversed the antiapoptotic effect. A potential mechanism underlying SPHK1-induced cisplatin resistance and apoptosis inhibition may be activation of STAT3 via binding non-POU domain containing octamer binding. In conclusion, the present study suggested that SPHK1 displayed significant antiapoptotic effects in cisplatin-based treatment, thus may serve as a potential novel therapeutic target for the treatment for bladder cancer.

Pharmacological Effects of Polyphenol Phytochemicals on the JAK-STAT Signaling Pathway

The JAK-STAT signaling pathway is a common pathway of many cytokine signal transductions, closely related to cell proliferation, apoptosis, differentiation, and inflammatory response. It is essential for inhibiting the inflammatory response, initiating innate immunity, and coordinating adaptive immune mechanisms. Owing to the nature of this pathway and its potential cross-epitopes with multiple alternative pathways, the long-term efficacy of monotherapy-based adaptive targeting therapy is limited, and the majority of drugs targeting STATs are still in the preclinical phase. Meanwhile, curcumin, quercetin, and several kinds of plant polyphenol chemicals play roles in multiple sites of the JAK-STAT pathway to suppress abnormal activation. Polyphenol compounds have shown remarkable effects by acting on the JAK-STAT pathway in anti-inflammatory, antitumor, and cardiovascular disease control. This review summarizes the pharmacological effects of more than 20 kinds of phytochemicals on JAK-STAT signaling pathway according to the chemical structure of polyphenolic phytochemicals.

Dehydrocrenatidine inhibits head and neck cancer cells invasion and migration by modulating JNK1/2 and ERK1/2 pathway and decreases MMP-2 expression

Head and neck cancer is associated with poor prognosis because of its highly metastatic nature. For the better management of head and neck cancer patients, it is very important to diagnose the cancer at an early stage, as well as to prevent the rapid spread of cancer either through direct invasion or lymphatic metastasis. In present study, the effect of dehydrocrenatidine, which is a beta-carboline alkaloid found in the medicinal plant Picrasma quassioides, on human head and neck cancer metastasis was investigated. The study results revealed the treatment of FaDu, SCC9, and SCC47 cells with 5, 10, and 20 μM of dehydrocrenatidine significantly decreased the motility, migration, and invasion of head and neck cancer cells. Moreover, the dehydrocrenatidine treatment significantly decreased the expression of MMP-2 and phosphorylation of ERK1/2 and JNK1/2. Additional experiments revealed that the cotreatment of dehydrocrenatidine with either ERK1/2 or JNK1/2 inhibitor caused further reduction in cancer cell motility and migration compared to that in dehydrocrenatidine treatment alone. Moreover, similar trend was observed in case of ERK1/2 and JNK1/2 phosphorylation and MMP-2 expression after the cotreatment. Taken together, the mechanism by which dehydrocrenatidine can decrease the phosphorylation of ERK1/2 and JNK1/2, follow decrease the expression of MMP-2 and inhibits head and neck cancer cells invasion and migration. This present study identifies dehydrocrenatidine as a potent antimetastatic agent that can be used clinically to improve head and neck cancer prognosis.

Silibinin Suppresses Tumor Cell-Intrinsic Resistance to Nintedanib and Enhances Its Clinical Activity in Lung Cancer

The anti-angiogenic agent nintedanib has been shown to prolong overall and progression-free survival in patients with advanced non-small-cell lung cancer (NSCLC) who progress after first-line platinum-based chemotherapy and second-line immunotherapy. Here, we explored the molecular basis and the clinical benefit of incorporating the STAT3 inhibitor silibinin-a flavonolignan extracted from milk thistle-into nintedanib-based schedules in advanced NSCLC. First, we assessed the nature of the tumoricidal interaction between nintedanib and silibinin and the underlying relevance of STAT3 activation in a panel of human NSCLC cell lines. NSCLC cells with poorer cytotoxic responses to nintedanib exhibited a persistent, nintedanib-unresponsive activated STAT3 state, and deactivation by co-treatment with silibinin promoted synergistic cytotoxicity. Second, we tested whether silibinin could impact the lysosomal sequestration of nintedanib, a lung cancer cell-intrinsic mechanism of nintedanib resistance. Silibinin partially, but significantly, reduced the massive lysosomal entrapment of nintedanib occurring in nintedanib-refractory NSCLC cells, augmenting the ability of nintedanib to reach its intracellular targets. Third, we conducted a retrospective, observational multicenter study to determine the efficacy of incorporating an oral nutraceutical product containing silibinin in patients with NSCLC receiving a nintedanib/docetaxel combination in second- and further-line settings (n = 59). Overall response rate, defined as the combined rates of complete and partial responses, was significantly higher in the study cohort receiving silibinin supplementation (55%) than in the control cohort (22%, p = 0.011). Silibinin therapy was associated with a significantly longer time to treatment failure in multivariate analysis (hazard ratio 0.43, p = 0.013), despite the lack of overall survival benefit (hazard ratio 0.63, p = 0.190). Molecular mechanisms dictating the cancer cell-intrinsic responsiveness to nintedanib, such as STAT3 activation and lysosomal trapping, are amenable to pharmacological intervention with silibinin. A prospective, powered clinical trial is warranted to confirm the clinical relevance of these findings in patients with advanced NSCLC.

Delivery and Anti-Psoriatic Effect of Silibinin-Loaded Polymeric Micelles: An Experimental Study in the Psoriatic Skin Model

OBJECTIVE

Psoriasis is an inflamed skin disorder associated with the activation of phosphorylation signals in keratinocytes, which leads to proliferation. Phosphorylation signal inhibitors, such as silibinin can inhibit cell proliferation. Unlike current psoriasis treatment approaches that are associated with dangerous side effects; natural components can introduce new trends in psoriasis treatment. The major problem in the topical treatment of psoriasis is drug localization through the psoriasis lesions.

METHODS

In this study, silibinin-loaded polymeric micelles prepared and characterized for drug loading and release and ex vivo permeation through psoriatic and normal mice skin. The optimized batch was used for the treatment of psoriasis lesions in the mice model.

RESULTS

The optimized batch demonstrated mean particle size 18.3 ± 2.1 nm, entrapment efficiency 75.8 ± 5.8%, and prolonged silibinin release. % Silibinin permeated through psoriatic skin after 48 treated by polymeric micelle and aqueous control was 80.35, and 92.6, respectively. Polymeric micelles increased silibinin localization in the psoriatic skin in comparison with control. In psoriatic skin after 7- 10 days treatment by silibinin- loaded polymeric micelle, there was no evidence of psoriasis and the histological evaluation showed no sign of psoriasis. Silibinin-loaded polymeric micelles reduced Psoriasis area index by more than 78% after 14 days.

CONCLUSION

It seems that polymeric micelles increased the effectiveness of silibinin by drug localization into the psoriatic plaque. Topical STAT- 3inhibitors can be introduced as a new strategy in psoriasis treatment.

Treatment for liver cancer: From sorafenib to natural products

Liver cancer most commonly develops in patients with chronic liver disease, the etiology of which includes viral hepatitis (B and C), alcohol, obesity, dietary carcinogens, and so forth. The current treatment modalities, including surgical resection and liver transplantation, have been found far from effective. Hence, there is an obvious critical need to develop alternative strategies for the treatment of it. In this review, we discuss the formation process and therapeutic targets of liver cancer. Currently, targeted therapy is limited to sorafenib, lenvatinib, regorafenib, ramucirumab and cabozantinib which leads to a survival benefit in patients, but on the other hand is hampered by the occurrence of drug resistance. Pleasingly and importantly, there are multiple natural products undergoing clinical evaluation in liver cancer, such as polyphenols like icaritin, resveratrol, and silybin, saponins including ginsenoside Rg3 and glycyrrhizinate, alkaloid containing irinotecan and berberine and inorganic compound arsenic trioxide at present. Preclinical and clinical studies have shown that these compounds inhibit liver cancer formation owing to the influence on the anti-viral, anti-inflammation, anti-oxidant, anti-angiogenesis and anti-metastasis activity. Furthermore, a series of small molecule derivatives inspired by the aforementioned compounds are designed and synthesized according to structure-activity relationship studies. Drug combination and novel type of drug-targeted delivery system thereof have been well developed. This article is ended by a perspective remark of futuristic development of natural product-based therapeutic regimen for liver cancer treatment. We expect that this review is an account for current status of natural products as promising anti-liver cancer treatments and should contribute to its understanding.

Lung Cancer Management with Silibinin: A Historical and Translational Perspective

The flavonolignan silibinin, the major bioactive component of the silymarin extract of Silybum marianum (milk thistle) seeds, is gaining traction as a novel anti-cancer therapeutic. Here, we review the historical developments that have laid the groundwork for the evaluation of silibinin as a chemopreventive and therapeutic agent in human lung cancer, including translational insights into its mechanism of action to control the aggressive behavior of lung carcinoma subtypes prone to metastasis. First, we summarize the evidence from chemically induced primary lung tumors supporting a role for silibinin in lung cancer prevention. Second, we reassess the preclinical and clinical evidence on the effectiveness of silibinin against drug resistance and brain metastasis traits of lung carcinomas. Third, we revisit the transcription factor STAT3 as a central tumor-cell intrinsic and microenvironmental target of silibinin in primary lung tumors and brain metastasis. Finally, by unraveling the selective vulnerability of silibinin-treated tumor cells to drugs using CRISPR-based chemosensitivity screenings (e.g., the hexosamine biosynthesis pathway inhibitor azaserine), we illustrate how the therapeutic use of silibinin against targetable weaknesses might be capitalized in specific lung cancer subtypes (e.g., KRAS/STK11 co-mutant tumors). Forthcoming studies should take up the challenge of developing silibinin and/or next-generation silibinin derivatives as novel lung cancer-preventive and therapeutic biomolecules.

The Anticancer Properties of Silibinin: Its Molecular Mechanism and Therapeutic Effect in Breast Cancer

BACKGROUND

Silibinin (SB), the main component of Silymarin (SM), is a natural substance obtained from the seeds of the milk thistle. SM contains up to 70% of SB as two isoforms: A and B. It has an antioxidant and anti-inflammatory effect on hepatocytes and is known to inhibit cell proliferation, induce apoptosis, and curb angiogenesis. SB has demonstrated activity against many cancers, such as skin, liver, lung, bladder, and breast carcinomas.

METHODS

This review presents current knowledge of the use of SM in breast cancer, this being one of the most common types of cancer in women. It describes selected molecular mechanisms of the action of SM; for example, although SB influences both Estrogen Receptors (ER), α and β, it has opposite effects on the two. Its action on ERα influences the PI3K/AKT/mTOR and RAS/ERK signaling pathways, while by up-regulating ERβ, it increases the numbers of apoptotic cells. In addition, ERα is involved in SB-induced autophagy, while ERβ is not. Interestingly, SB also inhibits metastasis by suppressing TGF-β2 expression, thus suppressing Epithelial to Mesenchymal Transition (EMT). It also influences migration and invasive potential via the Jak2/STAT3 pathway.

RESULTS

SB may be a promising enhancement of BC treatment: when combined with chemotherapeutic drugs such as carboplatin, cisplatin, and doxorubicin, the combination exerts a synergistic effect against cancer cells. This may be of value when treating aggressive types of mammary carcinoma.

CONCLUSION

Summarizing, SB inhibits proliferation, induces apoptosis, and restrains metastasis via several mechanisms. It is possible to combine SB with different anticancer drugs, an approach that represents a promising therapeutic strategy for patients suffering from BC.

Curcumol increases the sensitivity of colon cancer to 5-FU by regulating Wnt/β-catenin signaling

Background

5-fluorouracil (5-FU) resistance is the leading cause of treatment failure in colon cancer. Combination therapy is an effective strategy to inhibit cancer cells and prevent drug resistance. Therefore, we studied the antitumor effect of curcumol alone or combined with 5-FU on human colon cancer drug-resistant cells.

Methods

The 5-FU resistant HCT116 cell line (HCT116/5-FU) was established by repeated exposure to gradually increasing concentrations of 5-FU; Cell viability was measured by cell counting kit-8 (CCK-8); apoptosis rate of HCT116 cells was detected using Annexin V-fluorescein isothiocyanate (FITC) assay kit; cell proliferation and invasion were detected using colony formation assays, wound healing assay and transwell invasion assays; activity of transplanted tumor in vivo in specific pathogen free (SPF) BALB/c nude mice (6 weeks old, male) was monitored by bioluminescence imaging, immunohistochemistry and western blot analysis.

Results

Our study showed the potent antitumor effect of curcumol by induction of apoptosis, inhibition of proliferation, invasion, migration, and improvement of the therapeutic efficacy of 5-FU toward human colon cancer HCT116 cells. From our results, curcumol could chemosensitize 5-FU-resistant HCT116 cells. The combination of curcumol and 5-FU exerted a synergistic inhibitory effect on the induction of apoptosis. Also, this combination inhibited the proliferation, invasion, and migration of both chemo-resistant and sensitive cells. Curcumol treatment decreased multidrug resistance-associated protein 2 (MRP-2), P-glycoprotein (P-gp), survivin, and β-catenin expression, which correlated with multidrug resistance (MDR) and the target genes of Wnt/β-catenin. It significantly increased the p-β-catenin level and Bad/Bcl-2 ratio in HCT116/5-FU cells compared with 5-FU treatment. In vivo, curcumol significantly inhibited the growth of transplanted tumors and the expression of Ki-67, proliferating cell nuclear antigen (PCNA), and vascular endothelial growth factor (VEGF) in colon cancer cells.

Conclusions

Curcumol as a potential chemotherapeutic agent combined with 5-FU can overcome colon cancer resistance.

Inhibition of TMEM16A by Natural Product Silibinin: Potential Lead Compounds for Treatment of Lung Adenocarcinoma

Background: Effective anticancer therapy can be achieved by identifying novel tumor-specific drug targets and screening of new drugs. Recently, TMEM16A has been identified to be overexpressed in lung adenocarcinoma, and inhibitors of TMEM16A showed obvious antitumor efficacy.

Methods: YFP fluorescence quenching and whole-cell patch clamp experiments were used to explore the inhibitory effect of silibinin on TMEM16A. Molecular docking and site-directed mutagenesis were performed to confirm the binding sites of silibinin and TMEM16A. MTT assay, wound healing assay, and annexin-V assay were used to detect the effect of silibinin on cancer cell proliferation, migration, and apoptosis. shRNA was transfected into LA795 cells to knock down the expression of endogenous TMEM16A. Tumor xenograft mice combined with Western blot experiments reveal the inhibitory effect and mechanism of silibinin in vivo.

Results: Silibinin concentration dependently inhibited the whole-cell current of TMEM16A with an IC₅₀ of 30.90 ± 2.10 μM. The putative binding sites of silibinin in TMEM16A were K384, R515, and R535. The proliferation and migration of LA795 cells were downregulated by silibinin, and the inhibition effect can be abolished by knockdown of the endogenous TMEM16A. Further, silibinin was injected to tumor xenograft mice which exhibited significant antitumor activity without weight loss. Finally, Western blotting results showed the mechanism of silibinin inhibiting lung adenocarcinoma was through apoptosis and downregulation of cyclin D1.

Conclusion: Silibinin is a novel TMEM16A inhibitor, and it can be used as a lead compound for the development of lung adenocarcinoma therapy drugs.

An update on investigational therapies that target STAT3 for the treatment of cancer

INTRODUCTION

Signal transducer and activator of transcription 3 (STAT3) is involved in cancer initiation and resistance to chemo-radiation therapies and targeted agents. The role of STAT3 in inflammation and immunity together with its involvement in a variety of diseases including genitourinary, gastrointestinal, lung, ovarian and brain tumors makes STAT3 an ideal candidate for therapeutic strategies.

AREAS COVERED

The authors provided an overview on STAT3 inhibitors and examined the most recent results obtained by these agents in cancer patients. The authors discussed the results published since 2015 and the ongoing clinical trials on anti-STAT3 agents in cancer patients. The authors also provide our opinion on the future perspectives of this therapeutic approach in this context. The manuscript includes information from trial databases and scientific literature.

EXPERT OPINION

Future challenges include the development of non-peptide small-molecule inhibitors of STAT3 designed to directly inhibit STAT3 activity. In addition, inhibitors of STAT3/STAT3 nuclear translocation or DNA binding activity are also emerging as novel promising therapeutic approaches A better comprehension of the role of STAT3 in modulating immune response together with advances in understanding the mechanisms of STAT3-induced chemo and/or radio-resistance will also help the design of combined strategies in cancer patients.

Identification of miRNAs as diagnostic and prognostic markers in hepatocellular carcinoma

The development of high-throughput technologies has yielded a large amount of data from molecular and epigenetic analysis that could be useful for identifying novel biomarkers of cancers. We analyzed Gene Expression Omnibus (GEO) DataSet micro–ribonucleic acid (miRNA) profiling datasets to identify miRNAs that could have value as diagnostic and prognostic biomarkers in hepatocellular carcinoma (HCC). We adopted several computing methods to identify the functional roles of these miRNAs. Ultimately, via integrated analysis of three GEO DataSets, three differential miRNAs were identified as valuable markers in HCC. Combining the results of receiver operating characteristic (ROC) analyses and Kaplan–Meier Plotter (KM) survival analyses, we identified hsa-let-7e as a novel potential biomarker for HCC diagnosis and prognosis. Then, we found via quantitative reverse-transcription polymerase chain reaction (RT-qPCR) that let-7e was upregulated in HCC tissues and that such upregulation was significantly associated with poor prognosis in HCC. The results of functional analysis indicated that upregulated let-7e promoted tumor cell growth and proliferation. Additionally, via mechanistic analysis, we found that let-7e could regulate mitochondrial apoptosis and autophagy to adjust and control cancer cell proliferation. Therefore, the integrated results of our bioinformatics analyses of both clinical and experimental data showed that let-7e was a novel biomarker for HCC diagnosis and prognosis and might be a new treatment target.

Polyphenolic molecules targeting STAT3 pathway for the treatment of cancer

Cancer is accounted as the second-highest cause of morbidity and mortality throughout the world. Numerous preclinical and clinical investigations have consistently highlighted the role of natural polyphenolic compounds against various cancers. A plethora of potential bioactive polyphenolic molecules, primarily flavonoids, phenolic acids, lignans and stilbenes, have been explored from the natural sources for their chemopreventive and chemoprotective activities. Moreover, combinations of these polyphenols with current chemotherapeutic agents have also demonstrated their strong role against both progression and resistance of malignancies. Signal transducer and activator of transcription 3 (STAT3) is a ubiquitously-expressed signaling molecule in almost all body cells. Thousands of literatures have revealed that STAT3 plays significant roles in promoting the cellular proliferation, differentiation, cell cycle progression, metastasis, angiogenesis and immunosuppression as well as chemoresistance through the regulation of its downstream target genes such as Bcl-2, Bcl-xL, cyclin D1, c-Myc and survivin. For its key role in cancer development, researchers considered STAT3 as a major target for cancer therapy that mainly focuses on abrogating the expression (activation or phosphorylation) of STAT3 in tumor cells both directly and indirectly. Polyphenolic molecules have explicated their protective actions in malignant cells via targeting STAT3 both in vitro and in vivo. In this article, we reviewed how polyphenolic compounds as well as their combinations with other chemotherapeutic drugs inhibit cancer cells by targeting STAT3 signaling pathway.

MicroRNA-140-5p regulates the proliferation, apoptosis and inflammation of RA FLSs by repressing STAT3

Ectopic expression of microRNA (miRNA) in rheumatoid arthritis (RA) fibroblast-like synoviocyte (RA FLS) is associated with the development of rheumatoid arthritis. The present study aimed to evaluate the effects of miRNA-140-5p (miR-140) on the properties of RA FLSs. It was found that miR-140 expression was decreased in 33 RA patients and extracted RA FLS samples, when compared to the corresponding healthy controls. Abnormally increased miR-140 expression in RA FLSs attenuated cell proliferation and increased cell apoptosis. Additionally, reduced pro-inflammatory cytokine production was observed in RA FLSs transfected with a miR-140 precursor. Furthermore, the 3'-UTR of the signal transducer and activator of transcription (STAT) 3 gene was identified as a target of miR-140. Notably, restoration of STAT3 expression rescued the regulatory effect of miR-140 on the proliferation, apoptosis and inflammatory cytokine production of RA FLSs. Therefore, the current findings indicated that miR-140 is a crucial modulator of both proliferation and apoptosis, shedding light on the etiology behind RA FLS viability, which is modulated by an interplay between miR-140 and STAT3 in the context of RA.

Transcriptome profiling reveals Silibinin dose-dependent response network in non-small lung cancer cells

Silibinin (SIL), a natural flavonolignan from the milk thistle (Silybum marianum), is known to exhibit remarkable hepatoprotective, antineoplastic and EMT inhibiting effects in different cancer cells by targeting multiple molecular targets and pathways. However, the predominant majority of previous studies investigated effects of this phytocompound in a one particular cell line. Here, we carry out a systematic analysis of dose-dependent viability response to SIL in five non-small cell lung cancer (NSCLC) lines that gradually differ with respect to their intrinsic EMT stage. By correlating gene expression profiles of NSCLC cell lines with the pattern of their SIL IC50 response, a group of cell cycle, survival and stress responsive genes, including some prominent targets of STAT3 (BIRC5, FOXM1, BRCA1), was identified. The relevancy of these computationally selected genes to SIL viability response of NSCLC cells was confirmed by the transient knockdown test. In contrast to other EMT-inhibiting compounds, no correlation between the SIL IC50 and the intrinsic EMT stage of NSCLC cells was observed. Our experimental results show that SIL viability response of differently constituted NSCLC cells is linked to a subnetwork of tightly interconnected genes whose transcriptomic pattern can be used as a benchmark for assessment of individual SIL sensitivity instead of the conventional EMT signature. Insights gained in this study pave the way for optimization of customized adjuvant therapy of malignancies using Silibinin.

Downregulation of N-myc Interactor Promotes Cervical Cancer Cells Growth by Activating Stat3 Signaling

N-myc interactor (NMI), a member of the oncogene Myc family, has been reported to be closely related to the development of cancer. However, the character of NMI in cervical carcinoma has not been reported. Herein, we found that downregulation of NMI protein not only promoted the proliferation, migration, and invasion of HeLa cells, but also decreased their expression of Caspase-3 and Caspase-9. Silencing NMI promotes the epithelial-mesenchymal transition of human cervical carcinoma HeLa cells by upregulating N-cadherin, vimentin, and downregulating E-cadherin. Further investigation illustrated the downregulation of NMI can activate the STAT3 signaling pathway. In conclusion, we found that the downregulation of NMI plays an important role in the progression of cervical cancer, and may served as a novel therapeutic target for cervical cancer.