Morin inhibits STAT3 tyrosine 705 phosphorylation in tumor cells through activation of protein tyrosine phosphatase SHP1. Biochem Pharmacol. 2013;85:898-912. [PMID: 23279849 DOI: 10.1016/j.bcp.2012.12.018]

Isotoosendanin exerts anti-tumor effects in NSCLC by enhancing the stability of SHP-2 and inhibiting the JAK/STAT3 pathway

BACKGROUND

Lung cancer has been considered as a serious problem for the public health system. NSCLC is the main type of lung cancer, and finding improved treatments for NSCLC is a pressing concern. In this study, we have explored the efficacy of isotoosendanin (ITSN) for the treatment of NSCLC, and also explored the potential underlying mechanisms.

METHODS

NSCLC cells were cultured, and colony formation, cell cycle as well as apoptosis assays have been conducted for investigating the biological functions of ITSN on NSCLC cells. Furthermore, target genes of ITSN have been predicted via PharmMapper and SuperPred database, subsequently validated using the drug affinity responsive target stability (DARTS) approach, a cellular thermal shift assay (CETSA) as well as surface plasmon resonance (SPR) analysis. Additionally, ubiquitination experiments have been conducted for the level of ubiquitination of the NSCLC cells. Finally, a nude mouse xenograft model has been established for evaluating the anti-tumor effects of ITSN in vivo.

RESULTS

ITSN has shown anti-NSCLC activities both in vitro and in vivo. Mechanistically, ITSN interacts with SHP-2 through enhancing its stability and decreases the level of ubiquitination. Notably, ITSN may regulate the behaviors of NSCLC cells via affecting the JAK/STAT3 signaling, and finally, the anti-tumor effects of ITSN was partially reversed by the application of SHP-2 inhibitor or siRNA of SHP-2.

CONCLUSIONS

ITSN may exert its anti-tumor effects by directly targeting SHP-2, increasing its stability and minimizing its ubiquitination. These results imply that ITSN could be a revolutionary component for treating NSCLC.

Morin inhibits osteosarcoma migration and invasion by suppressing urokinase plasminogen activator through a signal transducer and an activator of transcription 3

Osteosarcoma, the most common primary bone cancer that affects adolescents worldwide, has the early metastatic potential to be responsible for high mortality rates. Morin has a multipurpose role in numerous cancers, whereas little is known about its role in osteosarcoma migration and invasion. Therefore, we hypothesized that morin suppresses the invasive activities and the migratory potential of human osteosarcoma cells. Our results showed that morin reduced migration and invasion capabilities in human osteosarcoma U2OS and HOS cells. Moreover, morin inhibited the urokinase plasminogen activator (uPA) expression through a signal transducer and an activator of transcription-3 (STAT3) phosphorylation. After STAT3 overexpression, the decrease of the migratory potential and uPA expression caused by 100 μM of morin in U2OS cells was countered, indicating that STAT3 contributes to the antimetastatic property of morin in human osteosarcoma cells by reducing uPA. In conclusion, morin may be a potential candidate for the antimetastatic treatment of human osteosarcoma.

Intestinal Inflammation and Regeneration-Interdigitating Processes Controlled by Dietary Lipids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a disease of chronic inflammatory conditions of the intestinal tract due to disturbance of the inflammation and immune system. Symptoms of IBD include abdominal pain, diarrhea, bleeding, reduced weight, and fatigue. In IBD, the immune system attacks the intestinal tract's inner wall, causing chronic inflammation and tissue damage. In particular, interlukin-6 and interlukin-17 act on immune cells, including T cells and macrophages, to amplify the immune responses so that tissue damage and morphological changes occur. Of note, excessive calorie intake and obesity also affect the immune system due to inflammation caused by lipotoxicity and changes in lipids supply. Similarly, individuals with IBD have alterations in liver function after sustained high-fat diet feeding. In addition, excess dietary fat intake, along with alterations in primary and secondary bile acids in the colon, can affect the onset and progression of IBD because inflammatory cytokines contribute to insulin resistance; the factors include the release of inflammatory cytokines, oxidative stress, and changes in intestinal microflora, which may also contribute to disease progression. However, interfering with de novo fatty acid synthase by deleting the enzyme acetyl-CoA-carboxylase 1 in intestinal epithelial cells (IEC) leads to the deficiency of epithelial crypt structures and tissue regeneration, which seems to be due to Lgr5+ intestinal stem cell function. Thus, conflicting reports exist regarding high-fat diet effects on IBD animal models. This review will focus on the pathological basis of the link between dietary lipids intake and IBD and will cover the currently available pharmacological approaches.

Natural bioactive compounds and STAT3 against hepatocellular carcinoma: An update

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

Role of bio-flavonols and their derivatives in improving mitochondrial dysfunctions associated with pancreatic tumorigenesis

Mitochondria, a cellular metabolic center, efficiently fulfill cellular energy needs and regulate crucial metabolic processes, including cellular proliferation, differentiation, apoptosis, and generation of reactive oxygen species. Alteration in the mitochondrial functions leads to metabolic imbalances and altered extracellular matrix dynamics in the host, utilized by solid tumors like pancreatic cancer (PC) to get energy benefits for fast-growing cancer cells. PC is highly heterogeneous and remains unidentified for a longer time because of its complex pathophysiology, retroperitoneal position, and lack of efficient diagnostic approaches, which is the foremost reason for accounting for the seventh leading cause of cancer-related deaths worldwide. PC cells often respond poorly to current therapeutics because of dense stromal barriers in the pancreatic tumor microenvironment, which limit the drug delivery and distribution of antitumor immune cell populations. As an alternative approach, various natural compounds like flavonoids are reported to possess potent antioxidant and anticancerous properties and are less toxic than current chemotherapeutic drugs. Therefore, we aim to summarize the current state of knowledge regarding the pharmacological properties of flavonols in PC in this review from the perspective of mitigating mitochondrial dysfunctions associated with cancer cells. Our literature survey indicates that flavonols efficiently regulate cellular metabolism by scavenging reactive oxygen species, mitigating inflammation, and arresting the cell cycle to promote apoptosis in tumor cells via intrinsic mitochondrial pathways. In particular, flavonols proficiently inhibit the cancer-associated proliferation and inflammatory pathways such as EGFR/MAPK, PI3K/Akt, and nuclear factor κB in PC. Overall, this review provides in-depth evidence about the therapeutic potential of flavonols for future anticancer strategies against PC; still, more multidisciplinary human interventional studies are required to dissect their pharmacological effect accurately.

Flavonoid Myricetin as Potent Anticancer Agent: A Possibility towards Development of Potential Anticancer Nutraceuticals

Good nutrition plays a crucial role in maintaining a balanced lifestyle. The beneficial effects of nutrition have been found to counteract nutritional disturbances with the expanded use of nutraceuticals to treat and manage cardiovascular diseases, cancer, and other developmental defects over the last decade. Flavonoids are found abundantly in plant-derived foods such as fruits, vegetables, tea, cocoa, and wine. Fruits and vegetables contain phytochemicals like flavonoids, phenolics, alkaloids, saponins, and terpenoids. Flavonoids can act as anti-inflammatory, anti-allergic, anti-microbial (antibacterial, antifungal, and antiviral) antioxidant, anti-cancer, and anti-diarrheal agents. Flavonoids are also reported to upregulate apoptotic activity in several cancers such as hepatic, pancreatic, breast, esophageal, and colon. Myricetin is a flavonol which is naturally present in fruits and vegetables and has shown possible nutraceutical value. Myricetin has been portrayed as a potent nutraceutical that may protect against cancer. The focus of the present review is to present an updated account of studies demonstrating the anticancer potential of myricetin and the molecular mechanisms involved therein. A better understanding of the molecular mechanism(s) underlying its anticancer activity would eventually help in its development as a novel anticancer nutraceutical having minimal side effects.

Consideration of SHP-1 as a Molecular Target for Tumor Therapy

Abnormal activation of receptor tyrosine kinases (RTKs) contributes to tumorigenesis, while protein tyrosine phosphatases (PTPs) contribute to tumor control. One of the most representative PTPs is Src homology region 2 (SH2) domain-containing phosphatase 1 (SHP-1), which is associated with either an increased or decreased survival rate depending on the cancer type. Hypermethylation in the promoter region of PTPN6, the gene for the SHP-1 protein, is a representative epigenetic regulation mechanism that suppresses the expression of SHP-1 in tumor cells. SHP-1 comprises two SH2 domains (N-SH2 and C-SH2) and a catalytic PTP domain. Intramolecular interactions between the N-SH2 and PTP domains inhibit SHP-1 activity. Opening of the PTP domain by a conformational change in SHP-1 increases enzymatic activity and contributes to a tumor control phenotype by inhibiting the activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT3) pathway. Although various compounds that increase SHP-1 activation or expression have been proposed as tumor therapeutics, except sorafenib and its derivatives, few candidates have demonstrated clinical significance. In some cancers, SHP-1 expression and activation contribute to a tumorigenic phenotype by inducing a tumor-friendly microenvironment. Therefore, developing anticancer drugs targeting SHP-1 must consider the effect of SHP-1 on both cell biological mechanisms of SHP-1 in tumor cells and the tumor microenvironment according to the target cancer type. Furthermore, the use of combination therapies should be considered.

Morin Sensitizes MDA-MB-231 Triple-Negative Breast Cancer Cells to Doxorubicin Cytotoxicity by Suppressing FOXM1 and Attenuating EGFR/STAT3 Signaling Pathways

Considerable emphasis is being placed on combinatorial chemotherapeutic/natural treatments for breast cancer. This study reveals the synergistic anti-tumor activity of morin and Doxorubicin (Dox) co-treatment on MDA-MB-231 triple-negative breast cancer (TNBC) cell proliferation. Morin/Dox treatment promoted Dox uptake and induced DNA damage and formation of nuclear foci of p-H2A.X. Furthermore, DNA repair proteins, RAD51 and survivin, and cell cycle proteins, cyclin B1 and forkhead Box M1 (FOXM1), were induced by Dox alone but attenuated by morin/Dox co-treatment. In addition, Annexin V/7-AAD analysis revealed that necrotic cell death after co-treatment and apoptotic cell death by Dox alone were associated with the induction of cleaved PARP and caspase-7 without Bcl-2 family involvement. FOXM1 inhibition by thiostrepton showed that co-treatment caused FOXM1-mediated cell death. Furthermore, co-treatment downregulated the phosphorylation of EGFR and STAT3. Flow cytometry showed that the accumulation of cells in the G2/M and S phases might be linked to cellular Dox uptake, p21 upregulation, and cyclin D1 downregulation. Taken together, our study shows that the anti-tumor effect of morin/Dox co-treatment is due to the suppression of FOXM1 and attenuation of EGFR/STAT3 signaling pathways in MDA-MB-231 TNBC cells, which suggests that morin offers a means of improving therapeutic efficacy in TNBC patients.

The Role of Natural Flavonoids as Telomerase Inhibitors in Suppressing Cancer Growth

Cancer is a complex and multifaceted group of diseases characterized by the uncontrolled growth and spread of abnormal cells. While cancer can be challenging and life-altering, advances in research and development have led to the identification of new promising anti-cancer targets. Telomerase is one such target that is overexpressed in almost all cancer cells and plays a critical role in maintaining telomere length, which is essential for cell proliferation and survival. Inhibiting telomerase activity can lead to telomere shortening and eventual cell death, thus presenting itself as a potential target for cancer therapy. Naturally occurring flavonoids are a class of compounds that have already been shown to possess different biological properties, including the anti-cancer property. They are present in various everyday food sources and richly present in fruits, nuts, soybeans, vegetables, tea, wine, and berries, to name a few. Thus, these flavonoids could inhibit or deactivate telomerase expression in cancer cells by different mechanisms, which include inhibiting the expression of hTERT, mRNA, protein, and nuclear translocation, inhibiting the binding of transcription factors to hTERT promoters, and even telomere shortening. Numerous cell line studies and in vivo experiments have supported this hypothesis, and this development could serve as a vital and innovative therapeutic option for cancer. In this light, we aim to elucidate the role of telomerase as a potential anti-cancer target. Subsequently, we have illustrated that how commonly found natural flavonoids demonstrate their anti-cancer activity via telomerase inactivation in different cancer types, thus proving the potential of these naturally occurring flavonoids as useful therapeutic agents.

Crosstalk between xanthine oxidase (XO) inhibiting and cancer chemotherapeutic properties of comestible flavonoids- a comprehensive update

Gout is an inflammatory disease caused by metabolic disorder or genetic inheritance. People throughout the world are strongly dependent on ethnomedicine for the treatment of gout and some receive satisfactory curative treatment. The natural remedies as well as established drugs derived from natural sources or synthetically made exert their action by mechanisms that are closely associated with anticancer treatment mechanisms regarding inhibition of xanthine oxidase, feedback inhibition of de novo purine synthesis, depolymerization and disappearance of microtubule, inhibition of NF-ĸB activation, induction of TRAIL, promotion of apoptosis, and caspase activation and proteasome inhibition. Some anti-gout and anticancer novel compounds interact with same receptors for their action, e.g., colchicine and colchicine analogues. Dietary flavonoids, i.e., chrysin, kaempferol, quercetin, fisetin, pelargonidin, apigenin, luteolin, myricetin, isorhamnetin, phloretinetc etc. have comparable IC₅₀ values with established anti-gout drug and effective against both cancer and gout. Moreover, a noticeable number of newer anticancer compounds have already been isolated from plants that have been using by local traditional healers and herbal practitioners to treat gout. Therefore, the anti-gout plants might have greater potentiality to become selective candidates for screening of newer anticancer leads.

Synergistically Anti-Multiple Myeloma Effects: Flavonoid, Non-Flavonoid Polyphenols, and Bortezomib

Multiple myeloma (MM) is a clonal plasma cell tumor originating from a post-mitotic lymphoid B-cell lineage. Bortezomib(BTZ), a first-generation protease inhibitor, has increased overall survival, progression-free survival, and remission rates in patients with MM since its clinical approval in 2003. However, the use of BTZ is challenged by the malignant features of MM and drug resistance. Polyphenols, classified into flavonoid and non-flavonoid polyphenols, have potential health-promoting activities, including anti-cancer. Previous preclinical studies have demonstrated the anti-MM potential of some dietary polyphenols. Therefore, these dietary polyphenols have the potential to be alternative therapies in anti-MM treatment regimens. This systematic review examines the synergistic effects of flavonoids and non-flavonoid polyphenols on the anti-MM impacts of BTZ. Preclinical studies on flavonoids and non-flavonoid polyphenols-BTZ synergism in MM were collected from PubMed, Web of Science, and Embase published between 2008 and 2020. 19 valid preclinical studies (Published from 2008 to 2020) were included in this systematic review. These studies demonstrated that eight flavonoids (icariin, icariside II, (-)-epigallocatechin-3-gallate, scutellarein, wogonin, morin, formononetin, daidzin), one plant extract rich in flavonoids (Punica granatum juice) and four non-flavonoid polyphenols (silibinin, resveratrol, curcumin, caffeic acid) synergistically enhanced the anti-MM effect of BTZ. These synergistic effects are mediated through the regulation of cellular signaling pathways associated with proliferation, apoptosis, and drug resistance. Given the above, flavonoids and non-flavonoid polyphenols can benefit MM patients by overcoming the challenges faced in BTZ treatment. Despite the positive nature of this preclinical evidence, some additional investigations are still needed before proceeding with clinical studies. For this purpose, we conclude by providing some suggestions for future research directions.

Intracellular Pathways and Mechanisms of Colored Secondary Metabolites in Cancer Therapy

Despite the great advancements made in cancer treatment, there are still many unsatisfied aspects, such as the wide palette of side effects and the drug resistance. There is an obvious increasing scientific attention towards nature and what it can offer the human race. Natural products can be used to treat many diseases, of which some plant products are currently used to treat cancer. Plants produce secondary metabolites for their signaling mechanisms and natural defense. A variety of plant-derived products have shown promising anticancer properties in vitro and in vivo. Rather than recreating the natural production environment, ongoing studies are currently setting various strategies to significantly manipulate the quantity of anticancer molecules in plants. This review focuses on the recently studied secondary metabolite agents that have shown promising anticancer activity, outlining their potential mechanisms of action and pathways.

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.

The anticarcinogenic and anticancer effects of the dietary flavonoid, morin: Current status, challenges, and future perspectives

Flavonoids constitute one of the most important classes of polyphenols, which have been found to have a wide range of biological activities such as anticancer effects. A large body of evidence demonstrates that morin as a pleiotropic dietary flavonoid possesses potent anticarcinogenic and anticancer activities with minimal toxicity against normal cells. The present review comprehensively elaborates the molecular mechanisms underlying antitumorigenic and anticancer effects of morin. Morin exerts its anticarcinogenic effects through multiple cancer preventive mechanisms, including reduction of oxidative stress, activation of phase II enzymes, induction of apoptosis, attenuation of inflammatory mediators, and downregulation of p-Akt and NF-κB expression. A variety of molecular targets and signaling pathways such as apoptosis, cell cycle, reactive oxygen species (ROS), matrix metalloproteinases (MMPs), epithelial-mesenchymal transition (EMT), and microRNAs (miRNAs) as well as signal transducer and activator of transcription 3 (STAT3), NF-κB, phosphatidylinositol 3-kinase (PI3K)/Akt, mitogen-activated protein kinase (MAPK), and Hippo pathways have been found to be involved in the anticancer effects of morin. In the adjuvant therapy, morin has been shown to have synergistic anticancer effects with several chemotherapeutic drugs. The findings of this review indicate that morin can act as a promising chemopreventive and chemotherapeutic agent.

Morin as an imminent functional food ingredient: an update on its enhanced efficacy in the treatment and prevention of metabolic syndromes

Flavonoids represent polyphenolic plant secondary metabolites with a general structure of a 15-carbon skeleton comprising two phenyl rings and a heterocyclic ring. Over 5000 natural flavonoids (flavanones, flavanonols, and flavans) from various plants have been characterized. Several studies provide novel and promising insights into morin hydrate for its different biological activities against a series of metabolic syndromes. The present review is a rendition of its sources, chemistry, functional potency, and protective effects on metabolic syndromes ranging from cancer to brain injury. Most importantly this systematic review article also highlights the mechanisms of interest to morin-mediated management of metabolic disorders. The key mechanisms (anti-oxidative and anti-inflammatory) responsible for its therapeutic potential are well featured after collating the in vitro and in vivo study reports. As a whole, based on the prevailing information rationalizing its medicinal use, morin can be identified as a therapeutic agent for the expansion of human health.

Morin hydrate: A comprehensive review on novel natural dietary bioactive compound with versatile biological and pharmacological potential

Flavonoids are natural plant-derived dietary bioactive compounds having a substantial impact on human health. Morin hydrate is a bioflavonoid mainly obtained from fruits, stem, and leaves of Moraceae family members' plants. Plenty of evidences supported that morin hydrate exerts its beneficial effects against various chronic and life-threatening degenerative diseases. Our current article discloses the recent advances that have been studied to explore the biological/pharmacological properties and molecular mechanisms to better understand the beneficial and multiple health benefits of morin hydrate. Indeed, Morin hydrate exerts free radical scavenging, antioxidant, anti-inflammatory, anti-cancerous, anti-microbial, antidiabetic, anti-arthritis, cardioprotective, neuroprotective, nephroprotective, and hepatoprotective effects. Moreover, morin hydrate exhibits its pharmacological activities by modulating various cellular signaling pathways such as Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-қB), Mitogen-activated protein kinase (MAPK), Janus kinases/ Signal transducer and activator of transcription proteins (JAKs/STATs), Kelch-like ECH-associated protein1/Nuclear erythroid-2-related factor (Keap1/Nrf2), Endoplasmic reticulum (ER), Mitochondrial-mediated apoptosis, Wnt/β-catenin, and Mechanistic target of rapamycin (mTOR). Most importantly, morin hydrate has the potential to modulate a variety of biological networks. Therefore, it can be predicted that this therapeutically potent compound could serve as a dietary agent for the expansion of human health and might be helpful for the development of the novel drug in the future. However, due to the lack of clinical trials, special human clinical trials are needed to address the effects of morin hydrate on various life-threatening disparities to recommend morin and/or morin-rich foods with other foods or bioactive dietary components, as well as dose-response interaction and safety profile.

Low molecular weight protein tyrosine phosphatase as signaling hub of cancer hallmarks

In the past decade, significant progress has been made in understanding the role of protein tyrosine phosphatase as a positive regulator of tumor progression. In this scenario, our group was one of the first to report the involvement of the low molecular weight protein tyrosine phosphatase (LMWPTP or ACP1) in the process of resistance and migration of tumor cells. Later, we and others demonstrated a positive correlation between the amount of this enzyme in human tumors and the poor prognosis. With this information in mind, we asked if LMWPTP contribution to metastasis, would it have an action beyond the primary tumor site. We know that the amount of this enzyme in the tumor cell correlates positively with the ability of cancer cells to interact with platelets, an indication that this enzyme is also important for the survival of these cells in the bloodstream. Here, we discuss several molecular aspects that support the idea of LMWPTP as a signaling hub of cancer hallmarks. Chemical and genetic modulation of LMWPTP proved to shut down signaling pathways associated with cancer aggressiveness. Therefore, advances in the development of LMWPTP inhibitors have great applicability in human diseases such as cancer.

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.

Overview of Morin and Its Complementary Role as an Adjuvant for Anticancer Agents

The Global cancer incidence and mortality data released by the World Health Organization proposes that out of 18.1 million new cancer cases diagnosed, 9.8 million deaths occurred globally in 2018. Cancer is one of the major health burdens among non-communicable diseases globally responsible for impeding life expectancy in the present century. Disrupting hallmarks of cancer (such as prolonged inflammation, increased growth signal, tissue invasion and metastasis, unlimited proliferation and evasion of apoptosis) with dietary agents is of considerable focus for cancer prevention and therapy. In the last decade, a significant contribution has been provided in finding many plant-derived natural agents that can be identified as promising molecular cancer therapeutics. Our focus in this review is on one such natural dietary agent, Morin (3,5,7,2',4'-pentahydroxyflavone): a bioflavonoid. Morin exerts strong pharmacological properties against a multitude of cancer (liver cancer, cervical cancer, melanoma, breast cancer, prostate, and colon cancer). Recent progress has also been made in examining the potential of morin as a natural dietary agent for fostering the pharmacological effects of other well-known anticancer agents. This review provides an overview of morin and its derivatives in combination with anticancer agents for cancer prevention and therapy.

Shp1 in Solid Cancers and Their Therapy

Shp1 is a cytosolic tyrosine phosphatase that regulates a broad range of cellular functions and targets, modulating the flow of information from the cell membrane to the nucleus. While initially studied in the hematopoietic system, research conducted over the past years has expanded our understanding of the biological role of Shp1 to other tissues, proposing it as a novel tumor suppressor gene functionally involved in different hallmarks of cancer. The main mechanism by which Shp1 curbs cancer development and progression is the ability to attenuate and/or terminate signaling pathways controlling cell proliferation, survival, migration, and invasion. Thus, alterations in Shp1 function or expression can contribute to several human diseases, particularly cancer. In cancer cells, Shp1 activity can indeed be affected by mutations or epigenetic silencing that cause failure of Shp1-mediated homeostatic maintenance. This review will discuss the current knowledge of the cellular functions controlled by Shp1 in non-hematopoietic tissues and solid tumors, the mechanisms that regulate Shp1 expression, the role of its mutation/expression status in cancer and its value as potential target for cancer treatment. In addition, we report information gathered from the public available data from The Cancer Genome Atlas (TCGA) database on Shp1 genomic alterations and correlation with survival in solid cancers patients.

Flavonoids as Epigenetic Modulators for Prostate Cancer Prevention

Prostate cancer (PCa) is a multifactorial disease with an unclear etiology. Due to its high prevalence, long latency, and slow progression, PCa is an ideal target for chemoprevention strategies. Many research studies have highlighted the positive effects of natural flavonoids on chronic diseases, including PCa. Different classes of dietary flavonoids exhibit anti-oxidative, anti-inflammatory, anti-mutagenic, anti-aging, cardioprotective, anti-viral/bacterial and anti-carcinogenic properties. We overviewed the most recent evidence of the antitumoral effects exerted by dietary flavonoids, with a special focus on their epigenetic action in PCa. Epigenetic alterations have been identified as key initiating events in several kinds of cancer. Many dietary flavonoids have been found to reverse DNA aberrations that promote neoplastic transformation, particularly for PCa. The epigenetic targets of the actions of flavonoids include oncogenes and tumor suppressor genes, indirectly controlled through the regulation of epigenetic enzymes such as DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC). In addition, flavonoids were found capable of restoring miRNA and lncRNA expression that is altered during diseases. The optimization of the use of flavonoids as natural epigenetic modulators for chemoprevention and as a possible treatment of PCa and other kinds of cancers could represent a promising and valid strategy to inhibit carcinogenesis and fight cancer.

Euxanthone represses the proliferation, migration, and invasion of glioblastoma cells by modulating STAT3/SHP-1 signaling

Glioblastoma is one of the most prevalent primary malignant brain tumors. Glioblastoma often develops resistance to conventional chemoradiotherapy, and thus, new ways to treat glioblastoma are urgently required. The aim of this study was to investigate the effect of euxanthone on the anticancer activities of glioblastoma and its potential mechanism. The U87 and U251 glioblastoma cell lines were cultured in media containing different concentrations of euxanthone. CCK-8 and colony formation assay were used to evaluate the cell proliferation. Cell migration and invasion were evaluated by wound healing and Transwell assays. Flow cytometry was used to assess the cell cycle and apoptosis rate. TUNEL assay was also employed to evaluate the apoptosis rate. Gene and protein expressions were determined by RT-qPCR and western blotting, respectively. A xenograft model was established to evaluate the efficacy of euxanthone in vivo. Euxanthone significantly repressed cell viability, migration, invasion, and epithelial-to-mesenchymal transition of U87 and U251 cells; and increased the rate of apoptosis. Western blotting results revealed that the levels of p21, p27, cleaved caspase-3, Bax, TIMP-3, and E-cadherin were upregulated while, the levels of CDK4, CDK6, pro-caspase-3, Bcl-2, MMP-2, MMP-9, N-cadherin, and Vimentin were downregulated by euxanthone. In addition, the expression of p-STAT3 was decreased, while the expression of SHP-1 was upregulated by euxanthone. We proposed that euxanthone could repress the malignant behavior of glioblastoma cells through suppression of STAT3 phosphorylation and activation of SHP-1. Further, in vivo data demonstrated that euxanthone repressed tumor growth and promoted apoptosis.

Association between obesity and breast cancer: Molecular bases and the effect of flavonoids in signaling pathways

Obesity is an abnormal or excessive accumulation of fat that leads to different health problems, such as cancer, where the adipocytes promote the proliferation, migration, and invasion of cancer cells, especially in the breast, where the epithelial cells are immersed in a fatty environment, and the interactions between these two types of cells involve, not only adipokines but also local pro-inflammatory mechanisms and hypoxic processes generating anti-apoptotic signals, which are a common result in leptin signaling. The expression of the Vascular Endothelial Growth Factor (VEGF) and cyclin D1, results in the decrease in phosphorylation of AMPK, increasing the activity of the aromatase enzyme; alternatively, the adiponectin activates AMPK to reduce inflammation. Nevertheless, alterations of the JAK/STAT pathways contribute to mammary carcinogenesis, while the PI3K/AKT/mTOR pathway controls most of the cancer's characteristics such as the cell cycle, survival, differentiation, proliferation, motility, metabolism, and genetic stability. Therefore, the purpose of the present review is, through the accumulated scientific evidence, to find the concordance between the signaling pathways involved among obesity and breast cancer, which can be modulated by using flavonoids.

Therapeutic Potential of Morin in Ovalbumin-induced Allergic Asthma Via Modulation of SUMF2/IL-13 and BLT2/NF-kB Signaling Pathway

BACKGROUND

Allergic asthma is a chronic immune-inflammatory disorder, characterized by airway inflammation and airway hyperresponsiveness (AHR). Morin is a natural flavonoid reported to exhibit inhibitory action against IgE-mediated allergic response.

AIM

To determine the efficacy of murine model of ovalbumin (OVA)-induced AHR inhibition by morin and decipher the molecular mechanism involved.

MATERIALS AND METHODS

Sprague-Dawley rats were sensitized and challenged with OVA to induce AHR. Rats received treatment with morin (10, 30 and 100 mg/kg, p.o.) for the next 28 days.

RESULTS

Morin (30 and 100 mg/kg) significantly and dose-dependently attenuated (p < 0.01 and p < 0.001) OVA-induced alterations in pulse oxy and lung function test, increased bronchoalveolar lavage fluid cell counts, elevated total protein and albumin levels in serum, BALF, and lungs, increased serum total and OVA-specific IgE levels and, elevated oxidative stress levels in the lung. RT-PCR analysis revealed that morin treatment (30 and 100 mg/kg) significantly (p < 0.001) up-regulated SUMF2 mRNA expression in lungs whereas mRNA expressions of BLT2, NF-κB, and Th2-cytokine (TNF-α, IL-1β, IL-4, IL-6, and IL-13) were down-regulated significantly and dose-dependently (p < 0.01 and p < 0.001). Also, histologic and ultrastructural studies showed that morin significantly inhibited (p < 0.001) OVAinduced perivascular and peribranchial inflammatory infiltration and interstitial fibrosis.

CONCLUSION

Morin exhibited inhibitory effect against OVA-induced allergic asthma by activation of SUMF2 which impeded IL-13 expression and in turn attenuated Th2-cytokines, BLT2, NF-κB, and IgE levels to ameliorate AHR. Thus, our findings suggested that morin could be considered as a potential alternative therapeutic agent for the management of allergic asthma.

Natural products as a perspective for cancer pain management: A systematic review

BACKGROUND

Cancer is the leading cause of death in the world and one of the main symptoms affecting these individuals is chronic pain, which must be evaluated and treated in its various components. Several drugs are currently used, but beyond the high cost, they have harmful side effects to patients or are transitorily effective. Ergo, there is a need to look for new options for cancer pain relief. Natural products (NPs) present themselves as strong candidates for the development of new drugs for the treatment of chronic pain, such as cancer pain.

PURPOSE

This systematic review aimed to summarize current knowledge about the analgesic profile of NPs in cancer pain.

METHODS

The search included PubMed, Scopus and Web of Science (from inception to June 2018) sought to summarize the articles studying new proposals with NPs for the management of oncological pain. Two independent reviewers extracted data on study characteristics, methods and outcomes.

RESULTS

After an extensive survey, 21 articles were selected, which described the analgesic potential of 15 natural compounds to relieve cancer pain. After analyzing the data, it can be suggested that these NPs, which have targets in central and peripheral mechanisms, are interesting candidates for the treatment of cancer pain for addressing different pharmacological mechanisms (even innovative), but ensuring the safety of these compounds is still a challenge. Likewise, the cannabinoids compounds leave the front as the most promising compounds for direct applicability due to the clinical studies that have already been developed and the background already established about these effects on chronic pain.

CONCLUSION

Regarding these findings, it can be concluded that the variability of possible biological sites of action is strategic for new perspectives in the development of therapeutic proposals different from those available in the current market.

Discovery and Characterization of Two Classes of Selective Inhibitors of the Suppressor of the TCR Signaling Family of Proteins

The suppressor of T-cell receptor signaling (Sts) proteins, Sts-1, has recently emerged as a potential immunostimulatory target for drug development. Genetic inactivation of the Sts proteins dramatically increases host survival of systemic infection and leads to improved pathogen clearance. The protein tyrosine phosphatase (PTP) activity of these proteins arises from a C-terminal 2-histidine phosphatase (HP) domain. To identify new inhibitors of the HP activity of Sts-1, we miniaturized a phosphatase assay to a 1536-well format and conducted a 20 580 compound screen. Among the hits were two classes of structurally related compounds, tetracycline variants and sulfonated azo dyes. These hits had low micromolar to nanomolar IC₅₀ values. Orthogonal screening confirmed the validity of these inhibitors and demonstrated that both act competitively on Sts-1 phosphatase activity. When tested on other PTPs, PTP1B and SHP1, it was found that the tetracycline PTP1B, SHP1, the tetracycline variant (doxycycline), and the sulfonated azo dye (Congo red) are selective inhibitors of Sts-1_HP, with selectivity indices ranging from 19 to as high as 200. The planar polyaromatic moieties present in both classes of compounds suggested a common binding mode. The mutation of either tryptophan 494 or tyrosine 596, located near the active site of the protein, reduced the K_i of the inhibitors from 3- to 18-fold, indicating that these residues may help to promote the binding of substrates with aromatic groups. This work provides new insights into substrate selectivity mechanisms and describes two classes of compounds that can serve as probes of function or as a basis for future drug discovery.

Flavonoids and Their Biological Secrets

Flavonoids are tricyclic polyphenolic compounds naturally occurring in plants. Being nature’s antioxidants flavonoids have been shown to reduce the damages induced by oxidative stress in cells. Besides being an antioxidant, flavonols are demonstrated to have anti-infective properties, i.e., antiviral, antifungal, anti-angiogenic, anti-tumorigenic, and immunomodulatory bioproperties. Plants use them as one of their defense mechanisms against radiation-induced DNA damage and also for fungal infections. The use of flavonols for fabrication of new drugs has been underway with objectives to develop safer and effective therapeutic agents. This review covers 15 flavonols for their structure, biological properties, role in plant metabolisms, and current research focused on computational drug design using flavonols for searching drug leads.

Morin-dependent inhibition of low molecular weight protein tyrosine phosphatase (LMW-PTP) restores sensitivity to apoptosis during colon carcinogenesis: Studies in vitro and in vivo, in an Apc-driven model of colon cancer

LMW-PTP has been associated with the development of colorectal cancer (CRC) and with the resistance to chemotherapy in cancer cells. To clarify its role in vivo, we studied LMW-PTP expression in Pirc rats (F344/NTac-Apc ^am1137 ), genetically prone to CRC and resistant to apoptosis. In the morphologically normal mucosa (NM) of Pirc rats, a dramatic over-expression of LMW-PTP was found compared to wt rats (about 60 times higher). Moreover, LMW-PTP levels further increase in spontaneously developed Pirc colon tumors. To understand if and how LMW-PTP affects resistance to apoptosis, we studied CRC cell lines, sensitive (HT29 and HCT-116), or resistant (HT29R, HCT116R) to 5-Fluorouracil (5-FU): resistant cells over-express LMW-PTP. When resistant cells were challenged with morin, a polyphenol inhibiting LMW-PTP, a fast and dose-related down-regulation of LMW-PTP was observed. 5-FU and morin co-treatment dramatically decreased cell viability, increased apoptosis, and significantly impaired self-renewal ability of all the cancer cell lines we have studied. Similarly, we observed that, in Pirc rats, one-week morin administration (50 mg/kg) down-regulated LMW-PTP and restored the apoptotic response to 5-FU in the NM. Finally, administration of morin for a longer period led to a significant reduction in colon precancerous lesions, together with a down-regulation of LMW-PTP. Taken together, these results document the involvement of LMW-PTP in the process of CRC in vitro and in vivo. Morin treatment may be envisaged as a system to increase the sensitivity to chemotherapy and to prevent carcinogenesis.

Molecular and Genomic Landscape of Peripheral T-Cell Lymphoma

Peripheral T-cell lymphoma (PTCL) is an uncommon group of lymphoma covering a diverse spectrum of entities. Little was known regarding the molecular and genomic landscapes of these diseases until recently but the knowledge is still quite spotty with many rarer types of PTCL remain largely unexplored. In this chapter, the recent findings from gene expression profiling (GEP) studies, including profiling data on microRNA, where available, will be presented with emphasis on the implication on molecular diagnosis, prognostication, and the identification of new entities (PTCL-GATA3 and PTCL-TBX21) in the PTCL-NOS group. Recent studies using next-generation sequencing have unraveled the mutational landscape in a number of PTCL entities leading to a marked improvement in the understanding of their pathogenesis and biology. While many mutations are shared among PTCL entities, the frequency varies and certain mutations are quite unique to a specific entity. For example, TET2 is often mutated but this is particularly frequent (70-80%) in angioimmunoblastic T-cell lymphoma (AITL) and IDH2 R172 mutations appear to be unique for AITL. In general, chromatin modifiers and molecular components in the CD28/T-cell receptor signaling pathways are frequently mutated. The major findings will be summarized in this chapter correlating with GEP data and clinical features where appropriate. The mutational landscape of cutaneous T-cell lymphoma, specifically on mycosis fungoides and Sezary syndrome, will also be discussed.

Morin promotes prostate cancer cells chemosensitivity to paclitaxel through miR-155/GATA3 axis

Paclitaxel is a first-line microtubule-stabilizing drug in treating prostate cancer. However, most patients develop resistance and experience relapse. Morin (3,5,7,20,40-pentahydroxyflavone) is an anti-tumor flavonoid in a numerous types of cancer cells including breast, ovarian and lung cancers. We therefore researched the effects of morin as an adjuvant to paclitaxel in in treating DU145 and PC-3 cells in vitro and DU145 derived prostate cancers in nude mice models. The chemosensitivities of these cells to the treatments of morin and paclitaxel were tested through viability assays utilizing cell counting kit 8 (CCK-8) and apoptosis assays through flow cytometry analyses. MicroRNA (miRNA) microarray was employed to determine the changes in miRNA profile of morin treated DU145 cells. The results from microarrays were further certified by quantitative real-time reverse transcription-PCR (qRT-PCR). The underlying targets of miR-155 were verified using luciferase assays followed by Western blot assays. In the results, morin was capable of repressing the cell viabilities in the paclitaxel-treated cells. MiR-155might be an effective target that can be down-regulated in morin-treated cells. We also discovered that GATA binding protein 3 (GATA3) was directly repressed by miR-155, and the treatment of morin reversed the expression of GATA3. In conclusion, morin might be a potential adjuvant of paclitaxel in treating prostate cancer through regulating miR-155/GATA3 axis.

Morin inhibited lung cancer cells viability, growth, and migration by suppressing miR-135b and inducing its target CCNG2

Lung cancer is one of the most severe threats with the highest mortality rate to humans in the world. Recently, morin has been reported to have anti-tumor properties observed in several types of cancers. However, its mechanism is still unclear. We assessed the influences of morin on cell viability, colony formation, and migration ability of A549 and employed microRNA array to identify the microRNAs affected by morin. We found that morin-treated A549 cells showed statistically decreased cell viability, colony formation, and migration rate when comparing with the dimethyl sulfoxide-treated cells. Microarray results showed that with the treatment of morin, the expression level of miR-135b significantly reduced compared the control group, suggesting that morin may exert its anti-cancer property by suppressing the expression of miR-135b. In addition, we found a potential binding site of miR-135b within 3' untranslated region of CCNG2-encoding cyclin homolog cyclin-G2. We evidenced that miR-135b directly targets CCNG2, which could be a potential biomarker of lung cancer prognosis. Morin exerts its anti-tumor function via downregulating the expression of miR-135b that directly targets and represses CCNG2.

Amorfrutin A inhibits TNF-α induced JAK/STAT signaling, cell survival and proliferation of human cancer cells

CONTEXT

Amorfrutin A is a natural product isolated from the fruits of Amorpha fruticosa L. and has been shown to exhibit multiple bioeffector functions. In the present study, we investigated whether amorfrutin A exerts anticancer effects by inhibiting STAT3 activation in cervical cancer cells.

OBJECTIVE

To investigate the effectiveness of amorfrutin A as a treatment of cancer, and determine the underlying pharmacological mechanism of action.

MATERIALS AND METHODS

HeLa, SK-Hep1, MDA-MB-231 and HCT116 cells were used in this study. Major assays were luciferase reporter assay, MTT, Western blot analysis, immunofluorescence assay, reverse transcription-PCR (RT-PCR), flow cytometric analysis, EdU labeling and immunofluorescence, xenografted assay.

RESULTS

Amorfrutin A significantly inhibited tumor necrosis factor-α (TNF-α)-induced phosphorylation and nuclear translocation of STAT3 in human cervical carcinoma cells. Amorfrutin A also inhibited activation of the upstream kinases Janus-activated kinase 1 (JAK1), JAK2 and Src signaling pathways. Furthermore, amorfrutin A increased the expression of p53, p21, p27, induced cell cycle arrest in the G1 phase as well as decreased levels of various oncogene protein products. In vivo studies further confirmed the inhibitory effect of amorfrutin A on the expression of STAT3 proteins, leading to a decrease growth of HeLa cells in a xenograft tumor model.

DISCUSSION AND CONCLUSIONS

The results indicated that amorfrutin A is a potent inhibitor of STAT3 and provide new perspectives into the mechanism of its anticancer activity.

Phosphorylation of STAT3 at Tyr705 regulates MMP-9 production in epithelial ovarian cancer

Ovarian cancer's poor progression is closely associated with overexpression of matrix metalloproteinase 9 (MMP-9), which belongs to the class of enzymes believed to be involved in the degradation of extracellular matrix. However, the mechanisms underlying regulation of MMP-9 are not completely understood. STAT (signal transducer and activator of transcription) family of transcription factors is well known to be engaged in diverse cellular functions. Activation of STAT3 has been observed in a number of cancers, promoting tumorigenesis and metastasis via transcriptional activation of its target genes. In this study, we tested our hypothesis that STAT3 regulates MMP-9 gene expression in epithelial ovarian cancer. Using epithelial ovarian cancer cell lines as in vitro model, we show an abundance of phosphorylated STAT3 at Tyr705 (p-STAT3) in SKOV3 cell line. We further show that MMP-9 gene promoter was significantly enriched by p-STAT3, and IL-6 treatment led to a significant increase of MMP-9 at mRNA and protein levels, in addition to an association of p-STAT3 with MMP-9 gene. By using luciferase reporter assay, we determined that the STAT3 DNA responsive element of MMP-9 was sufficient to regulate transcriptional activity of a heterologous promoter. These results suggest that the phosphorylation of STAT3 regulates MMP-9 production in ovarian cancer, which might be responsible for its invasiveness and metastasis.

Regulation of cell signaling pathways by dietary agents for cancer prevention and treatment

Although it is widely accepted that better food habits do play important role in cancer prevention and treatment, how dietary agents mediate their effects remains poorly understood. More than thousand different polyphenols have been identified from dietary plants. In this review, we discuss the underlying mechanism by which dietary agents can modulate a variety of cell-signaling pathways linked to cancer, including transcription factors, nuclear factor κB (NF-κB), signal transducer and activator of transcription 3 (STAT3), activator protein-1 (AP-1), β-catenin/Wnt, peroxisome proliferator activator receptor- gamma (PPAR-γ), Sonic Hedgehog, and nuclear factor erythroid 2 (Nrf2); growth factors receptors (EGFR, VEGFR, IGF1-R); protein Kinases (Ras/Raf, mTOR, PI3K, Bcr-abl and AMPK); and pro-inflammatory mediators (TNF-α, interleukins, COX-2, 5-LOX). In addition, modulation of proteasome and epigenetic changes by the dietary agents also play a major role in their ability to control cancer. Both in vitro and animal based studies support the role of dietary agents in cancer. The efficacy of dietary agents by clinical trials has also been reported. Importantly, natural agents are already in clinical trials against different kinds of cancer. Overall both in vitro and in vivo studies performed with dietary agents strongly support their role in cancer prevention. Thus, the famous quote "Let food be thy medicine and medicine be thy food" made by Hippocrates 25 centuries ago still holds good.

Cryptotanshinone inhibits human glioma cell proliferation in vitro and in vivo through SHP-2-dependent inhibition of STAT3 activation

Malignant gliomas (MGs) are one of the most common primary brain cancers in adults with a high mortality rate and relapse rate. Thus, finding better effective approaches to treat MGs has become very urgent. Here, we studied the effects of cryptotanshinone (CTS) on MGs in vitro and in vivo, and explored the underlying mechanisms. Effects of CTS in vitro on cell proliferation, cycle, migration and invasion were evaluated. The activation of JAK/STATs signaling was detected by western blot and immunofluorescenc staining. SHP-2 inhibitor or SiRNA were used to determine the involvement of SHP-2. The in vivo anti-MGs activity of CTS was studied with nude mice bearing intracerebral U87 xenografts. Our results revealed that CTS significantly inhibited the proliferation of MGs in vitro via inhibiting STAT3 signal pathway. The cell cycle was arrested at G0/G1 phase. Although CTS did not change the expression of total SHP-2 protein, the tyrosine phosphatase activity of SHP-2 protein was increased by CTS treatment in a dose-dependent manner in vivo and in vitro. SHP-2 inhibitor or SiRNA could reverse the inhibitory effect of CTS on phosphorylation of STAT3 Tyr705. In vivo study also showed that CTS inhibited the intracranial tumor growth and extended survival of nude mice bearing intracerebral U87 xenografts, confirming an inhibitory effect of CTS on MGs. Our results indicated CTS may be a potential therapeutic agent for MGs. The inhibitory action of CTS is largely attributed to the inhibition of STAT3 Tyr705 phosphorylation with a novel mechanism of upregulating the tyrosine phosphatase activity of SHP-2 protein.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

Combination treatment with flavonoid morin and telomerase inhibitor MST‑312 reduces cancer stem cell traits by targeting STAT3 and telomerase

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. The malignant CRC that undergoes metastasis in the advanced stage is usually refractory to existing chemotherapy and shows a poor prognosis. However, to date, efficient targeted-therapy for metastatic CRC is ill-defined. We tested the hypothesis that combined treatment of flavonoid morin and telomerase inhibitor MST‑312 may reduce the cancer stem cell (CSC) traits. To characterize CSC phenotype, we performed the CD133/CD44 subpopulation profiling, tumorsphere formation assay, cell invasion assay and wound healing assay. We have examined the augmenting effects of the combined treatment of morin and MST‑312 for 5-FU (5-fluorouracil) efficacy in human colorectal cancer. Morin and MST‑312 combined treatment reduced CD133 (+) and CD44 (+) subpopulations in human colorectal and breast cancer cells, respectively. Tumorsphere formation and cell invasiveness were decreased with the morin and MST‑312 combination treatment. Consistent with these data, morin and MST‑312 treatment decreased the wound healing capacity of human breast cancer cells. Stress and apoptosis antibody arrays revealed that there were specific upregulated and downregulated proteins resulting from different treatments. Phosphorylation levels of BAD, p53 and Chk1 were enhanced upon morin/MST‑312 treatments in HT-29 cells, whereas caspase-3 cleavage level and expression of IκBα were downregulated by combined morin/MST‑312 treatment in SW620 cells. Finally, morin and MST‑312 co-treatment further augmented the 5-FU efficacy, chemosensitizing the 5-FU resistant human colorectal cancer cells. Taken together, our study suggests that novel targeted-therapy can be implemented by using flavonoid morin and telomerase inhibitor MST‑312 for improved cancer prognosis.

Recent updates of precision therapy for gastric cancer: Towards optimal tailored management

Signaling pathways of gastric carcinogenesis and gastric cancer progression are being avidly studied to seek optimal treatment of gastric cancer. Among them, hepatocyte growth factor (HGF)/c-MET, phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathways have been widely investigated. Their aberrant expression or mutation has been significantly associated with advanced stage or poor prognosis of gastric cancer. Recently, aberrations of immune checkpoints including programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) have been suggested as an important step in the formation of a microenvironment favorable for gastric cancer. Accomplishments in basic research have led to the development of novel agents targeting these signaling pathways. However, phase III studies of selective anti-HGF/c-MET antibodies and mTOR inhibitor failed to show significant benefits in terms of overall survival and progression-free survival. Few agents directly targeting STAT3 have been developed. However, this target is still critical issue in terms of chemoresistance, and SH2-containing protein tyrosine phosphatase 1 might be a significant link to effectively inhibit STAT3 activity. Inhibition of PD-1/PD-L1 showed durable efficacy in phase I studies, and phase III evaluation is warranted. Therapeutic strategy to concurrently inhibit multiple tyrosine kinases is a reasonable option, however, lapatinib needs to be further evaluated to identify good responders. Regorafenib has shown promising effectiveness in prolonging progression-free survival in a phase II study. In this topic highlight, we review the biologic roles and outcomes of clinical studies targeting these signaling pathways.

Tocilizumab inhibits neuronal cell apoptosis and activates STAT3 in cerebral infarction rat model

Cerebral infarction is a severe hypoxic ischemic necrosis with accelerated neuronal cell apoptosis in the brain. As a monoclonal antibody against interleukin 6, tocilizumab (TCZ) is widely used in immune diseases, whose function in cerebral infarction has not been studied. This study aims to reveal the role of TCZ in regulating neuronal cell apoptosis in cerebral infarction. The cerebral infarction rat model was constructed by middle cerebral artery occlusion and treated with TCZ. Cell apoptosis in hippocampus and cortex of the brain was examined with TUNEL method. Rat neuronal cells cultured in oxygen-glucose deprivation (OGD) conditions and treated with TCZ were used to compare cell viability and apoptosis. Apoptosis-related factors including B-cell lymphoma extra large (Bcl-xL) and Caspase 3, as well as the phosphorylated signal transducer and activator of transcription 3 (p-STAT3) in brain cortex were analyzed from the protein level. Results indicated that TCZ treatment could significantly prevent the promoted cell apoptosis caused by cerebral infarction or OGD (P < 0.05 or P < 0.01). In brain cortex of the rat model, TCZ up-regulated Bcl-xL and down-regulated Caspase 3, consistent with the inhibited cell apoptosis. It also promoted tyrosine 705 phosphorylation of STAT3, which might be the potential regulatory mechanism of TCZ in neuronal cells. This study provided evidence for the protective role of TCZ against neuronal cell apoptosis in cerebral infarction. Based on these fundamental data, TCZ is a promising option for treating cerebral infarction, but further investigations on related mechanisms are still necessary.

Multiple regulation pathways and pivotal biological functions of STAT3 in cancer

STAT3 is both a transcription activator and an oncogene that is tightly regulated under normal physiological conditions. However, abundant evidence indicates that STAT3 is persistently activated in several cancers, with a crucial position in tumor onset and progression. In addition to its traditional role in cancer cell proliferation, invasion, and migration, STAT3 also promotes cancer through altering gene expression via epigenetic modification, inducing epithelial–mesenchymal transition (EMT) phenotypes in cancer cells, regulating the tumor microenvironment, and promoting cancer stem cells (CSCs) self-renewal and differentiation. STAT3 is regulated not only by the canonical cytokines and growth factors, but also by the G-protein-coupled receptors, cadherin engagement, Toll-like receptors (TLRs), and microRNA (miRNA). Despite the presence of diverse regulators and pivotal biological functions in cancer, no effective therapeutic inventions are available for inhibiting STAT3 and acquiring potent antitumor effects in the clinic. An improved understanding of the complex roles of STAT3 in cancer is required to achieve optimal therapeutic effects.

Paeoniflorin inhibits human glioma cells via STAT3 degradation by the ubiquitin-proteasome pathway

We investigated the underlying mechanism for the potent proapoptotic effect of paeoniflorin (PF) on human glioma cells in vitro, focusing on signal transducer and activator of transcription 3 (STAT3) signaling. Significant time- and dose-dependent apoptosis and inhibition of proliferation were observed in PF-treated U87 and U251 glioma cells. Expression of STAT3, its active form phosphorylated STAT3 (p-STAT3), and several downstream molecules, including HIAP, Bcl-2, cyclin D1, and Survivin, were significantly downregulated upon PF treatment. Overexpression of STAT3 induced resistance to PF, suggesting that STAT3 was a critical target of PF. Interestingly, rapid downregulation of STAT3 was consistent with its accelerated degradation, but not with its dephosphorylation or transcriptional modulation. Using specific inhibitors, we demonstrated that the prodegradation effect of PF on STAT3 was mainly through the ubiquitin-proteasome pathway rather than via lysosomal degradation. These findings indicated that PF-induced growth suppression and apoptosis in human glioma cells through the proteasome-dependent degradation of STAT3.

Acidosis promotes invasiveness of breast cancer cells through ROS-AKT-NF-κB pathway

It is well known that acidic microenvironment promotes tumorigenesis, however, the underlying mechanism remains largely unknown. In the present study, we show that acidosis promotes invasiveness of breast cancer cells through a series of signaling events. First, our study indicates that NF-κB is a key factor for acidosis-induced cell invasion. Acidosis activates NF-κB without affecting STAT3 activity; knockdown of NF-κB p65 abrogates the acidosis-induced invasion activity. Next, we show that the activation of NF-κB is mediated through phosphorylation and degradation of IκBα; and phosphorylation and nuclear translocation of p65. Upstream to NF-κB signaling, AKT is activated under acidic conditions. Moreover, acidosis induces generation of reactive oxygen species (ROS) which can be suppressed by ROS scavengers, reversing the acidosis-induced activation of AKT and NF-κB, and invasiveness. As a negative regulator of AKT, PTEN is oxidized and inactivated by the acidosis-induced ROS. Finally, inhibition of NADPH oxidase (NOX) suppresses acidosis-induced ROS production, suggesting involvement of NOX in acidosis-induced signaling cascade. Of considerable interest, acidosis-induced ROS production and activation of AKT and NF-κB can be only detected in cancer cells, but not in non-malignant cells. Together, these results demonstrate a cancer specific acidosis-induced signaling cascade in breast cancer cells, leading to cell invasion.

Morin, a flavonoid from moraceae, induces apoptosis by induction of BAD protein in human leukemic cells

Evidence suggests that phytochemicals can safely modulate cancer cell biology and induce apoptosis. Here, we investigated the anti-cancer activity of morin, a flavone originally isolated from members of the Moraceae family in human leukemic cells, focusing on apoptosis. An anti-cancer effect of morin was screened with several human leukemic cell lines. U937 cells were most sensitive to morin, where it induced caspase-dependent apoptosis in a dose-dependent manner. It also induced loss of MMP (ΔΨ_m) along with cytochrome c release, down-regulated Bcl-2 protein, and up-regulated BAX proteins. The apoptotic activity of morin was significantly attenuated by Bcl-2 augmentation. In conclusion, morin induced caspase-dependent apoptosis through an intrinsic pathway by upregulating BAD proteins. In addition, Bcl-2 protein expression is also important in morin-induced apoptosis of U937 cells. This study provides evidence that morin might have anticancer properties in human leukemic cells.

Synthesis and characterisation of morin reduced gold nanoparticles and its cytotoxicity in MCF-7 cells

There is significant interest in investigating the therapeutic potential of phytochemical reduced and bound gold nanoparticles (AuNPs) as it bridges the gap between nanotechnology and therapy. In the present study, AuNPs prepared using the flavonoid morin (mAuNPs) are characterised and have been studied for their anti-cancer effects. The -OH groups of morin reduce Au(3+) and stabilize Au(0) to form spherical and crystalline mAuNPs. These mAuNPs are biocompatible towards normal human blood cells and breast epithelial cells. Through TEM analysis, we report that they are readily taken up by breast cancer cells (MCF-7) to induce cell death. Apoptosis has also been assessed by other morphological observations and cell viability studies. Flow cytometric studies reveal that the cells undergo a transient phase of apoptosis progressing towards secondary necrosis as the dose and time of mAuNPs treatment increases. The ability of mAuNPs to induce cell death in MCF-7 cells indicates its potential as an anti-cancer agent.