STAT3 as a target for inducing apoptosis in solid and hematological tumors. Cell Res. 2008;18:254-267. [PMID: 18227858 DOI: 10.1038/cr.2008.18]

Inhibition of the STAT3-EPHX2 axis promotes regression of ulcerative colitis by treatment with novel porphyrin derivative

LD4, a novel porphyrin derivative, has attracted much attention for its excellent anti-inflammatory properties. It can promote the healing of colonic mucosa, reduce inflammatory response, regulate oxidative stress, and thus improve ulcerative colitis (UC) symptoms. However, the specific signaling pathways of LD4-PDT involved in UC have not been explored. The present study aimed to elucidate the effects of LD4 on UC and to investigate the underlying mechanisms both in vivo and in vitro. We classified and screened the LD4-PDT proteomic data to obtain key targets. Proteomic data revealed that EPHX2 and STAT3 are key targets of LD4-PDT for UC. Moreover, transcription factor STAT3 positively regulates the expression of EPHX2. Inhibiting EPHX2 can prevent the activation of NF-κB signaling pathway. Next, through pharmacological inhibition experiments, we confirmed that LD4-PDT can reduce intestinal inflammation by inhibiting STAT3-EPHX2 axis. However, by treating normal intestinal epithelial cells and colon cancer cells with TPPU and Stattic, our data confirmed that the STAT3-EPHX2 axis does not exist in colon cancer. In this study, we demonstrated that the transcription factor STAT3 can positively regulate the expression of EPHX2 in normal colon. LD4 can alleviate UC by inhibiting the STAT3-EPHX2 axis, but this axis does not exist in colon cancer. LD4-PDT may become a new and effective method for treating UC.

Unraveling the Molecular Mechanisms of the Neurodevelopmental Consequences of Fetal Protein Deficiency: Insights From Rodent Models and Public Health Implications

Fetal brain development requires increased maternal protein intake to ensure that offspring reach their optimal cognitive potential in infancy and adulthood. While protein deficiency remains a prevalent issue in developing countries, it is also reemerging in Western societies due to the growing adoption of plant-based diets, some of which are monotonous and may fail to provide sufficient amino acids crucial for the brain's critical developmental phase. Confounding variables in human nutritional research have impeded our understanding of the precise impact of protein deficiency on fetal neurodevelopment, as well as its implications for childhood neurocognitive performance. Moreover, it remains unclear whether such deficiency could predispose to mental health problems in adulthood, mirroring observations in individuals exposed to prenatal famine. In this review, we sought to evaluate mechanistic data derived from rodent models, placing special emphasis on the involvement of neuroendocrine axes, the influence of sex and timing, epigenetic modifications, and cellular metabolism. Despite notable progress, critical knowledge gaps remain, including understanding the long-term reversibility of effects due to fetal protein restriction and the interplay between genetic predisposition and environmental factors. Enhancing our understanding of the precise mechanisms that connect prenatal nutrition to brain development in future research endeavors can be significantly advanced by integrating multiomics approaches and utilizing additional alternative models such as nonhuman primates. Furthermore, it is crucial to investigate potential interventions aimed at alleviating adverse outcomes. Ultimately, this research has profound implications for guiding public health strategies aimed at raising awareness about the crucial role of optimal maternal nutrition in supporting fetal neurodevelopment.

TTI-101 targets STAT3/c-Myc signaling pathway to suppress cervical cancer progression: an integrated experimental and computational analysis

BACKGROUND

Cervical cancer (CC) is a significant global health concern, demanding the consideration of novel therapeutic strategies. The signal transducer and activator of transcription 3 (STAT3) pathway has been implicated in cancer progression and is a potential target for therapeutic intervention. This study aimed to explore the therapeutic potential of TTI-101, a small molecule STAT3 inhibitor, in CC and investigate its underlying mechanisms.

METHODS

Molecular docking studies and molecular dynamics simulations were performed to explore the binding interaction between TTI-101 and STAT3 and assess the stability of the STAT3-TTI-101 complex. Cell viability assays, wound healing assays, colony formation assays, flow cytometry analysis, and gene expression analysis were conducted. In vivo xenograft models were used to assess the antitumor efficacy of TTI-101.

RESULTS

The in silico analysis shows a stable binding interaction between TTI-101 and STAT3. TTI-101 treatment inhibits cell viability, clonogenic ability, and cell migration in CC cells. Furthermore, TTI-101 induces apoptosis and cell cycle arrest. Analysis of apoptosis-related markers demonstrated dysregulation of Bax, Bcl-2, and Caspase-3 upon TTI-101 treatment. Moreover, TTI-101 caused G2/M phase arrest accompanied by a decrease in CDK1 and Cyclin B1 at mRNA levels. In the xenograft model, TTI-101 significantly inhibited tumor growth without adverse effects on body weight.

CONCLUSION

TTI-101 exhibited anticancer effects by targeting the STAT3/c-Myc signaling pathway, inducing cell cycle arrest, and promoting apoptosis in CC cells. These findings provide valuable insights into the development of novel therapeutic strategies for cervical cancer. Further investigation is warranted to validate the clinical application of TTI-101.

Fragment-based design and synthesis of coumarin-based thiazoles as dual c-MET/STAT-3 inhibitors for potential antitumor agents

c-MET and STAT-3 are significant targets for cancer treatments. Here, we describe a class of very effective dual STAT-3 and c-MET inhibitors with coumarin-based thiazoles (3a-o) as its scaffold. Spectroscopic evidence (NMR, HRMS, and HPLC) validated the structural discoveries of the new compounds. The cytotoxic activity of these compounds was also tested against a panel of cancer cells in accordance with US-NCI guidelines. Compound 3g proved to be active at 10 µM, thus it was automatically scheduled to be tested at five doses. Towards SNB-75 (CNS cancer cell line), compound 3g showed notable in vitro anti-cancer activity with GI50 = 1.43 μM. For the molecular targets, compound 3g displayed potent activity towards STAT-3 and c-MET having IC50 of 4.7 µM and 12.67, respectively, compared to Cabozantinib (IC50 = 15 nM of c-MET) and STAT-3-IN-3 (IC50 = 2.1 µM of STAT-3). Moreover, compound 3g significantly induced apoptosis in SNB-75 cells, causing a 3.04-fold increase in apoptotic cell death (treated cells exhibited 11.53 % overall apoptosis, against 3.04 % in reference cells) and a 3.58-fold increase in necrosis. Moreover, it arrests cells at the G2 phase. Dual inhibition of c-MET and STAT-3 protein kinase was further validated using RT-PCR. The target compound's binding mechanism was determined by the application of molecular docking.

Deciphering the impact of STAT3 activation mediated by PTPRT promoter hypermethylation as biomarker of response to paclitaxel-plus-cetuximab in patients with recurrent or metastatic squamous cell carcinoma of the head and neck

BACKGROUND

Squamous cell carcinoma of the head and neck (SCCHN) is an aggressive disease with poor prognosis. It is known that the activation of STAT3 signaling pathways promotes the development and progression of this neoplasia and it has been described the role of PTPRT as a negative regulator of STAT3. Then, we have evaluated the impact of them as biomarkers of outcome in a series of patients with recurrent and/or metastatic SCCHN treated with weekly paclitaxel-plus-cetuximab (ERBITAX) regimen.

PATIENTS AND METHODS

Between 2008 and 2017, 52 patients with recurrent/metastatic SCCHN were treated with ERBITAX at our center, 34 of whom had available tumor samples. Phosphorylated STAT3 (pSTAT3) protein expression was analyzed by immunohistochemistry, STAT3 mRNA expression by qPCR, and PTPRT promoter methylation by methylation-specific PCR. Molecular results were correlated with response rate (RR), progression-free survival (PFS), and overall survival (OS).

RESULTS

pSTAT3 overexpression was detected in 67% and PTPRT promoter hypermethylation in 41% of tumor samples. PTPRT promoter hypermethylation showed a trend towards an association with lower RR (21% vs. 60%; p = 0.06). A lower RR was also observed in patients with pSTAT3 overexpression (36% vs. 54%) and in those with high STAT3 mRNA levels (43% vs. 64%), but these differences did not reach statistical significance. PTPRT promoter hypermethylation correlated with pSTAT3 overexpression (p = 0.009) but not with STAT3 mRNA overexpression. OS and PFS was shorter in patients with activated STAT3, but the difference did not reach statistical significance.

CONCLUSIONS

Although this was a relatively small retrospective study, it provides preliminary indications of the potential role of the STAT3 pathway on outcome in SCCHN and confirms that PTPRT acts as a negative regulator of STAT3. Our findings warrant investigation in a larger patient cohort to determine if inactivating this pathway through specific targeted treatments could improve outcomes in recurrent/metastatic SCCHN patients.

A Genetically Engineered "Reinforced Concrete" Scaffold Regulates the N2 Neutrophil Innate Immune Cascade to Repair Bone Defects

The innate immune response is crucial to inflammation, but how neutrophils and macrophages act in bone repair and tissue engineering treatment strategies await clarification. In this study, it is found that N2 neutrophils release stronger "eat me" signals to induce macrophage phagocytosis and polarize into the M2 anti-inflammatory phenotype. Guided by this biological mechanism, a mesoporous bioactive glass scaffold (MBG) is filled with hyaluronic acid methacryloyl (HAMA) hydrogel loaded with Transforming growth factor-β1 (TGFβ1) adenovirus (Ad@H), constructing a genetically engineered composite scaffold (Ad@H/M). The scaffold not only has good hydrophilicity and biocompatibility, but also provides mechanical stress support for bone repair. Adenovirus infection quickly induces N2 neutrophils, upregulating NF-κB and MAPK signaling pathways through Toll-like receptor 4 (TLR4) to promote the inflammatory response and macrophage phagocytosis. Macrophages perform phagocytosis and polarize towards the M2 phenotype, mediating the inflammatory response by inhibiting the PI3K-AKT-NF-κB pathway, maintaining homeostasis of the osteogenic microenvironment. The role of the Ad@H/M scaffold in regulating early inflammation and promoting long-term bone regeneration is further validated in vivo. In brief, this study focuses on the cascade of reactions between neutrophils and macrophage subtypes, and reports a composite scaffold that coordinates the innate immune response to promote bone repair.

The potential of vascular normalization for sensitization to radiotherapy

Radiotherapy causes apoptosis mainly through direct or indirect damage to DNA via ionizing radiation, leading to DNA strand breaks. However, the efficacy of radiotherapy is attenuated in malignant tumor microenvironment (TME), such as hypoxia. Tumor vasculature, due to the imbalance of various angiogenic and anti-angiogenic factors, leads to irregular morphology of tumor neovasculature, disordered arrangement of endothelial cells, and too little peripheral coverage. This ultimately leads to a TME characterized by hypoxia, low pH and high interstitial pressure. This deleterious TME further exacerbates the adverse effects of tumor neovascularization and weakens the efficacy of conventional radiotherapy. Whereas normalization of blood vessels improves TME and thus the efficacy of radiotherapy. In addition to describing the research progress of radiotherapy sensitization and vascular normalization, this review focuses on the strategy and application prospect of modulating vascular normalization to improve the efficacy of radiotherapy sensitization.

Chronic Lymphocytic Leukemia (CLL)-Derived Extracellular Vesicles Educate Endothelial Cells to Become IL-6-Producing, CLL-Supportive Cells

We hypothesized that via extracellular vesicles (EVs), chronic lymphocytic leukemia (CLL) cells turn endothelial cells into CLL-supportive cells. To test this, we treated vein-derived (HUVECs) and artery-derived (HAOECs) endothelial cells with EVs isolated from the peripheral blood of 45 treatment-naïve patients. Endothelial cells took up CLL-EVs in a dose- and time-dependent manner. To test whether CLL-EVs turn endothelial cells into IL-6-producing cells, we exposed them to CLL-EVs and found a 50% increase in IL-6 levels. Subsequently, we filtered out the endothelial cells and added CLL cells to this IL-6-enriched medium. After 15 min, STAT3 became phosphorylated, and there was a 40% decrease in apoptosis rate, indicating that IL-6 activated the STAT3-dependent anti-apoptotic pathway. Phospho-proteomics analysis of CLL-EV-exposed endothelial cells revealed 23 phospho-proteins that were upregulated, and network analysis unraveled the central role of phospho-β-catenin. We transfected HUVECs with a β-catenin-containing plasmid and found by ELISA a 30% increase in the levels of IL-6 in the culture medium. By chromatin immunoprecipitation assay, we observed an increased binding of three transcription factors to the IL-6 promoter. Importantly, patients with CLL possess significantly higher levels of peripheral blood IL-6 compared to normal individuals, suggesting that the inducers of endothelial IL-6 are the neoplastic EVs derived from the CLL cells versus those of healthy people. Taken together, we found that CLL cells communicate with endothelial cells through EVs that they release. Once they are taken up by endothelial cells, they turn them into IL-6-producing cells.

Conofolidine: A Natural Plant Alkaloid That Causes Apoptosis and Senescence in Cancer Cells

Natural products contribute substantially to anticancer therapy; the plant kingdom provides an important source of molecules. Conofolidine is a novel Aspidosperma-Aspidosperma bisindole alkaloid isolated from the Malayan plant Tabernaemontana corymbosa. Herein, we report conofolidine's broad-spectrum anticancer activity together with that of three other bisindoles-conophylline, leucophyllidine, and bipleiophylline-against human-derived breast, colorectal, pancreatic, and lung carcinoma cell lines. Remarkably, conofolidine was able to induce apoptosis (e.g., in MDA-MB-468 breast) or senescence (e.g., in HT-29 colorectal) in cancer cells. Annexin V-FITC/PI, caspase activation, and PARP cleavage confirmed the former while positive β-gal staining corroborated the latter. Cell cycle perturbations were evident, comprising S-phase depletion, accompanied by downregulated CDK2, and cyclins (A2, D1) with p21 upregulation. Confocal imaging of HCT-116 cells revealed an induction of aberrant mitotic phenotypes-membrane blebbing, DNA-fragmentation with occasional multi-nucleation. DNA integrity assessment in HCT-116, MDA-MB-468, MIAPaCa-2, and HT-29 cells showed increased fluorescent γ-H2AX during the G1 cell cycle phase; γ-H2AX foci were validated in HCT-116 and MDA-MB-468 cells by confocal microscopy. Conofolidine increased oxidative stress, preceding apoptosis- and senescence-induction in most carcinoma cell lines as seen by enhanced ROS levels accompanied by increased NQO1 expression. Collectively, we present conofolidine as a putative potent anticancer agent capable of inducing heterogeneous modes of cancerous cell death in vitro, encouraging further preclinical evaluations of this natural product.

GPAT3 is a potential therapeutic target to overcome sorafenib resistance in hepatocellular carcinoma

Background: Sorafenib is the standard treatment for advanced hepatocellular carcinoma (HCC), but acquired resistance during the treatment greatly limits its clinical efficiency. Lipid metabolic disorder plays an important role in hepatocarcinogenesis. However, whether and how lipid metabolic reprogramming regulates sorafenib resistance of HCC cells remains vague. Methods: Sorafenib resistant HCC cells were established by continuous induction. UHPLC-MS/MS, proteomics, and flow cytometry were used to assess the lipid metabolism. ChIP and western blot were used to reflect the interaction of signal transducer and activator of transcription 3 (STAT3) with glycerol-3-phosphate acyltransferase 3 (GPAT3). Gain- and loss-of function studies were applied to explore the mechanism driving sorafenib resistance of HCC. Flow cytometry and CCK8 in vitro, and tumor size in vivo were used to evaluate the sorafenib sensitivity of HCC cells. Results: Our metabolome data revealed a significant enrichment of triglycerides in sorafenib-resistant HCC cells. Further analysis using proteomics and genomics techniques demonstrated a significant increase in the expression of GPAT3 in the sorafenib-resistant groups, which was found to be dependent on the activation of STAT3. The restoration of GPAT3 resensitized HCC cells to sorafenib, while overexpression of GPAT3 led to insensitivity to sorafenib. Mechanistically, GPAT3 upregulation increased triglyceride synthesis, which in turn stimulated the NF-κB/Bcl2 signaling pathway, resulting in apoptosis tolerance upon sorafenib treatment. Furthermore, our in vitro and in vivo studies revealed that pan-GPAT inhibitors effectively reversed sorafenib resistance in HCC cells. Conclusions: Our data demonstrate that GPAT3 elevation in HCC cells reprograms triglyceride metabolism which contributes to acquired resistance to sorafenib, which suggests GPAT3 as a potential target for enhancing the sensitivity of HCC to sorafenib.

Icariside I reduces breast cancer proliferation, apoptosis, invasion, and metastasis probably through inhibiting IL-6/STAT3 signaling pathway

OBJECTIVES

Breast cancer is a common malignancy in women. More than 90% of breast cancer deaths are caused by metastasis. Epimedii Folium (EF) is a commonly used herb with anti-tumor benefits, but its underlying mechanisms and active components for breast cancer prevention are little understood. This study assessed the therapeutic role of Icariside I (ICS I) in Epimedium flavonoids (EF) on lung metastasis of breast cancer, including the underlying mechanism.

METHODS

Western blot, RT-qPCR, wound healing assay, colony formation assay, and flow cytometry were used to investigate the inhibition of breast cancer cells growth and migration by EF and ICS I through disrupting the IL-6/STAT3 pathway. Combined with 4T1 breast cancer model in mice, Western blot, RT-qPCR, Hematoxylin and Eosin staining, immunohistochemistry were used to evaluate the therapeutic role of ICS I in proliferation, apoptosis, invasion, and metastasis of breast cancer.

KEY FINDINGS

EF can inhibit STAT3 phosphorylation and reduce the colony formation and migration of breast cancer cells. Detecting the active ingredients in EF, we found ICS I can reduce the activation of STAT3 in 4T1 breast cancer cells, impair colony formation and migration. Moreover, ICS I induced cells G1 phase arrest and modulated Cyclin D1, CDK4, bcl-2, and bax to inhibit proliferation and survival of breast cancer cells. Similarly, the in vivo studies demonstrated that ICS I significantly suppressed tumor development and lung metastasis in the 4T1 mouse model. Tumor cells in vehicle group were arranged in a spoke-like pattern with obvious heterogeneity, and multinucleated tumor giant cells were seen. But, the tumor cells in the ICS I group were disorganized and necrotic lysis was seen in some areas. In ICS I-treated group, tumors' STAT3 phosphorylation level, IL-6, Cyclin D1, CDK4, bcl-2, and vimentin expression were downregulated, bax and cleaved caspase 3 expression were upregulated. In the lung tissue, we could find less metastasis of breast cancer cells and less lung injury in the ICS I group. Besides, the expression of metastasis-related genes MMP9 and vimentin was decreased in the lung tissue of ICS I group.

CONCLUSIONS

These findings suggest that ICS I can inhibit breast cancer proliferation, apoptosis, invasion and metastasis probably via targeting IL-6/STAT3 pathway. Therefore, ICS I has the potential to become an innovative therapeutic candidate to breast cancer prevention and treatment.

Use of phosphotyrosine-containing peptides to target SH2 domains: Antagonist peptides of the Crk/CrkL-p130Cas axis

Protein-protein interactions between SH2 domains and segments of proteins that include a post-translationally phosphorylated tyrosine residue (pY) underpin numerous signal transduction cascades that allow cells to respond to their environment. Dysregulation of the writing, erasing, and reading of these posttranslational modifications is a hallmark of human disease, notably cancer. Elucidating the precise role of the SH2 domain-containing adaptor proteins Crk and CrkL in tumor cell migration and invasion is challenging because there are no specific and potent antagonists available. Crk and CrkL SH2s interact with a region of the docking protein p130Cas containing 15 potential pY-containing tetrapeptide motifs. This chapter summarizes recent efforts toward peptide antagonists for this Crk/CrkL-p130Cas interaction. We describe our protocol for recombinant expression and purification of Crk and CrkL SH2s for functional assays and our procedure to determine the consensus binding motif from the p130Cas sequence. To develop a more potent antagonist, we employ methods often associated with structure-based drug design. Computational docking using Rosetta FlexPepDock, which accounts for peptides having a greater number of conformational degrees of freedom than small organic molecules that typically constitute libraries, provides quantitative docking metrics to prioritize candidate peptides for experimental testing. A battery of biophysical assays, including fluorescence polarization, differential scanning fluorimetry and saturation transfer difference nuclear magnetic resonance spectroscopy, were employed to assess the candidates. In parallel, GST pulldown competition assays characterized protein-protein binding in vitro. Taken together, our methodology yields peptide antagonists of the Crk/CrkL-p130Cas axis that will be used to validate targets, assess druggability, foster in vitro assay development, and potentially serve as lead compounds for therapeutic intervention.

Oncogenic STAT Transcription Factors as Targets for Cancer Therapy: Innovative Strategies and Clinical Translation

Despite advances in our understanding of molecular aspects of oncogenesis, cancer remains a leading cause of death. The malignant behavior of a cancer cell is driven by the inappropriate activation of transcription factors. In particular, signal transducers and activators of transcription (STATs), which regulate many critical cellular processes such as proliferation, apoptosis, and differentiation, are frequently activated inappropriately in a wide spectrum of human cancers. Multiple signaling pathways converge on the STATs, highlighting their importance in the development and progression of oncogenic diseases. STAT3 and STAT5 are two members of the STAT protein family that are the most frequently activated in cancers and can drive cancer pathogenesis directly. The development of inhibitors targeting STAT3 and STAT5 has been the subject of intense investigations in the last decade, although effective treatment options remain limited. In this review, we investigate the specific roles of STAT3 and STAT5 in normal physiology and cancer biology, discuss the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators, and offer insights into novel therapeutic strategies to identify STAT inhibitors as cancer therapeutics.

Dual role of mesenchymal stem/stromal cells and their cell-free extracellular vesicles in colorectal cancer

Colorectal cancer (CRC) is one of the main causes of cancer-related deaths. However, the surgical control of the CRC progression is difficult, and in most cases, the metastasis leads to cancer-related mortality. Mesenchymal stem/stromal cells (MSCs) with potential translational applications in regenerative medicine have been widely researched for several years. MSCs could affect tumor development through secreting exosomes. The beneficial properties of stem cells are attributed to their cell-cell interactions as well as the secretion of paracrine factors in the tissue microenvironment. For several years, exosomes have been used as a cell-free therapy to regulate the fate of tumor cells in a tumor microenvironment. This review discusses the recent advances and current understanding of assessing MSC-derived exosomes for possible cell-free therapy in CRC.

New Ref-1/APE1 targeted inhibitors demonstrating improved potency for clinical applications in multiple cancer types

AP endonuclease-1/Redox factor-1 (APE1/Ref-1 or Ref-1) is a multifunctional protein that is overexpressed in most aggressive cancers and impacts various cancer cell signaling pathways. Ref-1's redox activity plays a significant role in activating transcription factors (TFs) such as NFκB, HIF1α, STAT3 and AP-1, which are crucial contributors to the development of tumors and metastatic growth. Therefore, development of potent, selective inhibitors to target Ref-1 redox function is an appealing approach for therapeutic intervention. A first-generation compound, APX3330 successfully completed phase I clinical trial in adults with progressing solid tumors with favorable response rate, pharmacokinetics (PK), and minimal toxicity. These positive results prompted us to develop more potent analogs of APX3330 to effectively target Ref-1 in solid tumors. In this study, we present structure-activity relationship (SAR) identification and validation of lead compounds that exhibit a greater potency and a similar or better safety profile to APX3330. In order to triage and characterize the most potent and on-target second-generation Ref-1 redox inhibitors, we assayed for PK, mouse and human S9 fraction metabolic stability, in silico ADMET properties, ligand-based WaterLOGSY NMR measurements, pharmacodynamic markers, cell viability in multiple cancer cell types, and two distinct 3-dimensional (3D) cell killing assays (Tumor-Microenvironment on a Chip and 3D spheroid). To characterize the effects of Ref-1 inhibition in vivo, global proteomics was used following treatment with the top four analogs. This study identified and characterized more potent inhibitors of Ref-1 redox function (that outperformed APX3330 by 5-10-fold) with PK studies demonstrating efficacious doses for translation to clinic.

Dienogest attenuates STAT3 activation in ovarian endometriotic cysts

OBJECTIVE

Recent studies have suggested that endometriosis could be the result of excessive activation of signal transducer and activator of transcription 3 (STAT3), which is associated with the regulation of essential cellular mechanisms such as proliferation, invasion, and apoptosis. That finding implies that regulating STAT3 activation could play a key role in treating endometriosis. In the present study, we aimed to evaluate whether the anti-endometriotic effects of dienogest is mediated by the regulation of STAT3 activation.

STUDY DESIGN

STAT3 activation was evaluated in normal endometrial and ovarian endometriotic tissues obtained from patients with/without preoperative dienogest treatment. A subsequent in vitro analysis with endometriotic cyst stromal cells (ECSCs) was used to confirm the direct influence of dienogest in STAT3 activation.

RESULT

STAT3 activation is significantly higher in endometriotic tissues from non-treated patients than in normal endometrial tissues, and that difference is reversed by preoperative administration of dienogest. Similarly, the inhibitory effects of dienogest on STAT3 activation are demonstrated by in vitro results showing that dienogest treatment significantly inhibits IL-6-stimulated STAT3 activation in cultured ECSCs. That inhibition was accompanied by decreased expression of proliferative (PCNA), invasive (MMP-2), and anti-apoptotic (BCL-2) proteins. Furthermore, downregulating STAT3 activity with siRNA decreased PCNA, MMP-2, and BCL-2 expression in IL-6-treated ECSCs.

CONCLUSION

Dienogest inhibits STAT3 activation in ECSCs, which affects their proliferation, invasiveness, and apoptosis.

Hepatocellular Carcinoma: Old and Emerging Therapeutic Targets

Liver cancer, predominantly hepatocellular carcinoma (HCC), globally ranks sixth in incidence and third in cancer-related deaths. HCC risk factors include non-viral hepatitis, alcohol abuse, environmental exposures, and genetic factors. No specific genetic alterations are unequivocally linked to HCC tumorigenesis. Current standard therapies include surgical options, systemic chemotherapy, and kinase inhibitors, like sorafenib and regorafenib. Immunotherapy, targeting immune checkpoints, represents a promising avenue. FDA-approved checkpoint inhibitors, such as atezolizumab and pembrolizumab, show efficacy, and combination therapies enhance clinical responses. Despite this, the treatment of hepatocellular carcinoma (HCC) remains a challenge, as the complex tumor ecosystem and the immunosuppressive microenvironment associated with it hamper the efficacy of the available therapeutic approaches. This review explores current and advanced approaches to treat HCC, considering both known and new potential targets, especially derived from proteomic analysis, which is today considered as the most promising approach. Exploring novel strategies, this review discusses antibody drug conjugates (ADCs), chimeric antigen receptor T-cell therapy (CAR-T), and engineered antibodies. It then reports a systematic analysis of the main ligand/receptor pairs and molecular pathways reported to be overexpressed in tumor cells, highlighting their potential and limitations. Finally, it discusses TGFβ, one of the most promising targets of the HCC microenvironment.

Glutamate is effective in decreasing opacity formed in galactose-induced cataract model

Although cataract is the leading cause of blindness worldwide, the detailed pathogenesis of cataract remains unclear, and clinically useful drug treatments are still lacking. In this study, we examined the effects of glutamate using an ex vivo model in which rat lens is cultured in a galactose-containing medium to induce opacity formation. After inducing lens opacity formation in galactose medium, glutamate was added, and the opacity decreased when the culture was continued. Next, microarray analysis was performed using samples in which the opacity was reduced by glutamate, and genes whose expression increased with galactose culture and decreased with the addition of glutamate were extracted. Subsequently, STRING analysis was performed on a group of genes that showed variation as a result of quantitative measurement of gene expression by RT-qPCR. The results suggest that apoptosis, oxidative stress, endoplasmic reticulum (ER) stress, cell proliferation, epithelial-mesenchymal transition (EMT), cytoskeleton, and histones are involved in the formation and reduction of opacity. Therefore, glutamate may reduce opacity by inhibiting oxidative stress and its downstream functions, and by regulating the cytoskeleton and cell proliferation.

CD1d protects against hepatocyte apoptosis in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Hepatocyte apoptosis, a well-defined form of cell death in non-alcoholic steatohepatitis (NASH), is considered the primary cause of liver inflammation and fibrosis. However, the mechanisms underlying the regulation of hepatocyte apoptosis in NASH remain largely unclear. We explored the anti-apoptotic effect of hepatocyte CD1d in NASH.

METHODS

Hepatocyte CD1d expression was analyzed in patients with NASH and mouse models. Hepatocyte-specific gene overexpression or knockdown and anti-CD1d crosslinking were used to investigate the anti-apoptotic effect of hepatocyte CD1d on lipotoxicity-, Fas-, and concanavalin (ConA)-mediated liver injuries. A high-fat diet, a methionine-choline-deficient diet, a Fas agonist, and ConA were used to induce lipotoxic and/or apoptotic liver injuries. Palmitic acid was used to mimic lipotoxicity-induced apoptosis in vitro.

RESULTS

We identified a dramatic decrease in CD1d expression in hepatocytes of patients with NASH and mouse models. Hepatocyte-specific CD1d overexpression and knockdown experiments collectively demonstrated that hepatocyte CD1d protected against hepatocyte apoptosis and alleviated hepatic inflammation and injuries in NASH mice. Furthermore, decreased JAK2-STAT3 signaling was observed in NASH patient livers. Mechanistically, anti-CD1d crosslinking on hepatocytes induced tyrosine phosphorylation of the CD1d cytoplasmic tail, leading to the recruitment and phosphorylation of JAK2. Phosphorylated JAK2 activated STAT3 and subsequently reduced apoptosis in hepatocytes, which was associated with an increase in anti-apoptotic effectors (Bcl-xL and Mcl-1) and a decrease in pro-apoptotic effectors (cleaved-caspase 3/7). Moreover, anti-CD1d crosslinking effectively protected against Fas- or ConA-mediated hepatocyte apoptosis and liver injury in mice.

CONCLUSIONS

Our study uncovered a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 axis in hepatocytes that conferred hepatoprotection and highlighted the potential of hepatocyte CD1d-directed therapy for liver injury and fibrosis in NASH, as well as in other liver diseases associated with hepatocyte apoptosis.

IMPACT AND IMPLICATIONS

Excessive and/or sustained hepatocyte apoptosis is critical in driving liver inflammation and injury. The mechanisms underlying the regulation of hepatocyte apoptosis in non-alcoholic steatohepatitis (NASH) remain largely unclear. Here, we found that CD1d expression in hepatocytes substantially decreases and negatively correlates with the severity of liver injury in patients with NASH. We further revealed a previously unrecognized anti-apoptotic CD1d-JAK2-STAT3 signaling axis in hepatocytes, which confers significant protection against liver injury in NASH and acute liver diseases. Thus, hepatocyte CD1d-targeted therapy could be a promising strategy to manipulate liver injury in both NASH and other hepatocyte apoptosis-related liver diseases.

Discovery of imidazopyridine-pyrazoline-hybrid structure as SHP-1 agonist that suppresses phospho-STAT3 signaling in human breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) promotes breast cancer malignancy and controls key processes including proliferation, differentiation, and survival in breast cancer cells. Although many methods for treating breast cancer have been improved, there is still a need to discover and develop new methods for breast cancer treatment. Therefore, we synthesized a new compound 2-(4-(2,3-dichlorophenyl)piperazin-1-yl)-1-(3-(2,6-dimethylimidazo[1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone (DIP). We aimed to evaluate the anti-cancer effect of DIP in breast cancer cells and clarify its mode of action. We noted that DIP abrogated STAT3 activation and STAT3 upstream kinases janus-activated kinase (JAK) and Src kinases. In addition, DIP promoted the levels of SHP-1 protein and acts as SHP-1 agonist. Further, silencing of SHP-1 gene reversed the DIP-induced attenuation of STAT3 activation and apoptosis. DIP also induced apoptosis through modulating PARP cleavage and oncogenic proteins. Moreover, DIP also significantly enhanced the apoptotic effects of docetaxel through the suppression of STAT3 activation in breast cancer cells. Overall, our data indicated that DIP may act as a suppressor of STAT3 cascade, and it could be a new therapeutic strategy in breast cancer cells.

Prevention of STAT3-related pathway in SK-N-SH cells by natural product astaxanthin

PURPOSE

Neuroblastoma (NB) is the most common solid malignancy in children. Despite current intensive treatment, the long-term event-free survival rate is less than 50% in these patients. Thus, patients with NB urgently need more valid treatment strategies. Previous research has shown that STAT3 may be an effective target in high-risk NB patients. However, there are no effective inhibitors in clinical evaluation with low toxicity and few side effects. Astaxanthin is a safe and natural anticancer product. In this study, we investigated whether astaxanthin could exert antitumor effects in the SK-N-SH neuroblastoma cancer cell line.

METHOD

MTT and colony formation assays were used to determine the effect of astaxanthin on the proliferation and colony formation of SK-N-SH cells. Flow cytometry assays were used to detect the apoptosis of SK-N-SH cells. The migration and invasion ability of SK-N-SH cells were detected by migration and invasion assays. Western blot and RT-PCR were used to detect the protein and mRNA levels. Animal experiments were carried out and cell apoptosis in tissues were assessed using a TUNEL assay.

RESULT

We confirmed that astaxanthin repressed proliferation, clone formation ability, migration and invasion and induced apoptosis in SK-N-SH cells through the STAT3 pathway. Furthermore, the highest inhibitory effect was observed when astaxanthin was combined with si-STAT3. The reason for this may be that the combination of astaxanthin and si-STAT3 can lower STAT3 expression further than astaxanthin or si-STAT3 alone.

CONCLUSION

Astaxanthin can exert anti-tumor effect on SK-N-SH cells. The inhibitory effect was the higher when astaxanthin was combined with si-STAT3.

Covalent LYTAC Enabled by DNA Aptamers for Immune Checkpoint Degradation Therapy

Immune checkpoint blockade (ICB) therapy, while achieving tremendous clinical successes, still suffers from a low objective response rate in clinical cancer treatment. As a proof-of-concept study, we propose a new immune checkpoint degradation (ICD) therapy relying on lysosome-targeting chimera (LYTAC) to deplete immune checkpoint programmed death ligand-1 (PD-L1) on the tumor cell surface. Our designed chimeric aptamer on one side targets lysosome-trafficking receptor, and on the other side allows biorthogonal covalent-conjugation-reinforced specific binding of PD-L1. This covalent LYTAC is able to hijack PD-L1 for lysosomal degradation with greatly improved efficiency over its noncovalent counterpart in complex in vivo environment. Beyond abolishing the PD-1/PD-L1 axis associated immune resistance, we demonstrate for the first time that LYTAC-triggered PD-L1 degradation could directly cause immunogenic apoptosis of tumor cells to elicit tumor-specific immune responses, offering unparalleled advantages over ICB antibody therapy. Remarkably, ICD therapy with covalent LYTAC achieves comparable or higher antitumor efficacy while causing significantly less inflammatory injury compared to antibody-based ICB therapy. Moreover, covalent LYTAC can serve as a general platform for specifically degrading other membrane-associated proteins, making it a promising tool for future applications. Our work presents a novel molecular tool for effective LYTAC in complex environments, offering valuable insights in pushing DNA-based LYTAC drugs toward in vivo and clinical applications.

In Situ Cocktail Nanovaccine for Cancer Immunotherapy

In situ vaccination is a desirable strategy for cancer immunotherapy due to its convenience and capacity to target tumor antigens. Here, an in situ nanovaccine based on a cationic peptide with cholesterol-modified, DP7-C, for cancer immunotherapy is rationally designed, and developed a cancer nanovaccine that is easy to preparate. The nanovaccine includes cocktail small interfering RNAs (siRNAs) and immunologic adjuvant CpG ODNs, has synergistic effect in the cancer treatment. This nanovaccine can induce tumor cell death, promote antigen presentation and relieve immune suppression in the tumor microenvironment (TME). Moreover, this nanovaccine is administered to CT26 (hot) and B16F10 (cold) tumor model mice, in which it targeted the primary tumors and induced systemic antitumor immunity to inhibit metastasis. It is validated that the nanovaccine can convert cold tumors into hot tumors. Furthermore, the nanovaccine increased the immune response to anti-PD-1 therapy by modulating the TME in both CT26- and B16F10-tumor-bearing mice. The siRNA cocktail/CpG ODN/self-assembling peptide nanovaccine is a simple and universal tool that can effectively generate specific tumor cell antigens and can be combined with immuno-oncology agents to enhance antitumor immune activity. The versatile methodology provides an alternative approach for developing cancer nanovaccines.

Sugiol Masters Apoptotic Precision to Halt Gastric Cancer Cell Proliferation

Sugiol, a natural compound with anticancer properties, has shown promise in various cancer types, but its potential in preventing gastric cancer remains uncertain. In this study, we aimed to examine the inhibitory effect of sugiol on human gastric cancer cell proliferation. Our findings demonstrate that sugiol effectively suppresses the proliferation of SNU-5 human gastric cancer cells, leading to apoptotic cell death. We assessed the chemo-preventive potential of sugiol via an MTT assay and confirmed the induction of oxidative stress using the H2DCFDA fluorescent dye. Treatment with sugiol at concentrations higher than 25 µM for 24 h resulted in an increase in intracellular levels of reactive oxygen species (ROS). This elevation of ROS levels inhibited cell-cycle progression and induced cell-cycle arrest at the G1 phase. Furthermore, our study revealed that sugiol reduces the viability and proliferation of SNU-5 cells in a dose-dependent manner. Importantly, ADME and toxicity analyses revealed that sugiol was effective and nontoxic at low doses. In parallel, we utilized the Swiss target prediction tool to identify potential targets for sugiol. Enzymes and nuclear receptors were identified as major targets. To gain insights into the molecular interactions, we performed structure-based molecular docking studies, focusing on the interaction between sugiol and STAT3. The docking results revealed strong binding interactions within the active site pocket of STAT3, with a binding affinity of -12.169 kcal/mole. Sugiol's -OH group, carbonyl group, and phenyl ring demonstrated hydrogen-bonding interactions with specific residues of the target protein, along with Vander Waals and hydrophobic interactions. These data suggest that sugiol has the potential to inhibit the phosphorylation of STAT3, which is known to play a crucial role in promoting the growth and survival of cancer cells. Targeting the dysregulated STAT3 signaling pathway holds promise as a therapeutic strategy for various human tumors. In combination with interventions that regulate cell cycle progression and mitigate the DNA damage response, the efficacy of these therapeutic approaches can be further enhanced. The findings from our study highlight the antiproliferative and apoptotic potential of sugiol against human gastric cancer cells (SNU-5). Moreover, the result underpins that sugiol's interactions with STAT3 may contribute to its inhibitory effects on cancer cell growth and proliferation. Further research is warranted to explore the full potential of sugiol as a therapeutic agent and its potential application in treating gastric cancer and other malignancies characterized by dysregulated STAT3 activity.

Delivery of siRNA using cationic rosette nanotubes for gene silencing

The quest for new therapeutic treatments for hereditary diseases has led to many advances in RNA interference (RNAi) and gene silencing. While this technique has the potential to address many problems, the key to its continued use is the development of effective delivery strategies that would reduce cellular toxicity and increase silencing efficiency. Rosette nanotubes (RNTs) are biomimetic supramolecular nanostructures formed through the self-assembly of hybrid guanine-cytosine (G∧C) DNA bases. Here, we used bioactive RNTs for siRNA delivery and gene silencing. Fifteen lysine-functionalized twin-G∧C motifs (KnT, n = 1 to 15) were synthesized using solid phase peptide synthesis to produce building blocks that self-assembled to produce cationic RNTs under physiological conditions. The intracellular uptake of siRNA delivered by the oligo-L-lysine RNTs was examined and it was found that the complexation of siRNA was affected by the cationic charges from the lysine residues and the length of RNTs formed, with the higher charged KnT RNTs delivering siRNA to the cells at a faster rate. In addition, by protecting siRNA from serum degradation, KnT RNTs were shown to deliver their cargo to the cells effectively via the endocytic pathway. A reduction in the expression (∼70%) of the target stat3 protein was observed during gene expression analysis in HCT116 and A549 cell lines.

Astragaloside IV against Alzheimer's disease via microglia-mediated neuroinflammation using network pharmacology and experimental validation

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases in the world. The effective therapeutic methods and drugs are still not clear. Astragaloside IV (AS-IV), a triterpenoid saponin isolated from the root of Huangqi, has a beneficial effect in the treatment of AD. However, whether AS-IV alters microglia in the inflammation of AD is still ambiguous. In our study, 99 common targets were collected between AS-IV and AD. BCL2 apoptosis regulator (Bcl-2), pro-apoptotic BCL-2 protein BAX, epidermal growth factor receptor (EGFR), and receptor tyrosine phosphatase type C (PTPRC) were screened for inflammation and microglia in the above targets by network pharmacology. Interleukin-1β (IL-1β) and EGFR both interact with signal transducer and activator of transcription 3 (STAT3) by a protein interaction network, and IL-1β had a higher affinity for AS-IV based on molecular docking. Enrichment revealed targets involved in the regulation of neuronal cell bodies, growth factor receptor binding, EGFR tyrosine kinase inhibitor resistance., etc. Besides, AS-IV alleviated the reduced cell proliferation in amyloid-beta (Aβ)-treated microglial BV2 cells. AS-IV affected BV2 cell morphological changes and decreased cluster of differentiation 11b (CD11b) gene, IL-1β, and EGFR mRNA levels increment during lipopolysaccharide (LPS) injury in BV2 cell activation. Therefore, AS-IV may regulate microglial activation and inflammation via EGFR-dependent pathways in AD. EGFR and IL-1β are vital targets that may relate to each other to coregulate downstream molecular functions in the cure of AD. Our study provides a candidate drug and disease target for the treatment of neurodegenerative diseases in the clinic.

Curcumin potentiates the anti-inflammatory effects of Tehranolide by modulating the STAT3/NF-κB signaling pathway in breast and ovarian cancer cell lines

BACKGROUND

Studies have demonstrated that natural products, such as curcumin and artemisinin, possess anti-inflammatory effects, which can be beneficial for cancer treatment. Tehranolide, as a novel natural product, has a wide range of biological activities, including anti-cancer effects. However, many properties of Tehranolide, like its anti-inflammatory activity and its combination with curcumin, have not been investigated yet. This investigation examined the anti-inflammatory activity of Tehranolide, either alone or in combination with curcumin, via modulating the NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) and STAT3 (signal transducer and activator of transcription 3) signaling pathways in MDA-MB-231 and SKOV3, breast and ovarian cancer cell lines.

METHODS

ELISA-based methods were employed to measure the pro-inflammatory cytokine levels and the NF-κB activity in lipopolysaccharide (LPS)-induced cells. The real-time PCR experiment and Griess test were performed to evaluate inducible nitric oxide synthase (iNOS) gene expression and nitrite levels, respectively. The STAT3 and NF-κB signaling pathways were investigated by Western blotting analysis. Tehranolide's anti-cancer activity was also assessed in a mouse model of breast cancer using the TUNEL (terminal deoxynucleotidyl transferase nick-end labeling) assay.

RESULTS

Tehranolide diminished levels of pro-inflammatory cytokines in cancer cells. Additionally, it suppressed NF-κB DNA binding and STAT3 phosphorylation, reducing iNOS gene expression and nitrite production. Moreover, Western blotting showed that Tehranolide enhanced the inhibitory κB (IκBα) and Bcl-2 (B-cell lymphoma 2)-associated X (BAX) expression, and downregulated the expression of Bcl-2 proteins. Furthermore, the TUNEL assay demonstrated that Tehranolide induced apoptosis in a breast cancer mouse model. Curcumin potentiated all the anti-inflammatory effects of Tehranolide.

CONCLUSION

This investigation indicated for the first time that Tehranolide, either alone or in combination with curcumin, exerted its anti-inflammatory effects by suppressing NF-κB and STAT3 signaling pathways in SKOV3 and MDA-MB-231 cells.

A novel imidazo[1,2-a]pyridine derivative and its co-administration with curcumin exert anti-inflammatory effects by modulating the STAT3/NF-κB/iNOS/COX-2 signaling pathway in breast and ovarian cancer cell lines

Introduction

Imidazo[1,2-a]pyridine derivatives with diverse pharmacological properties and curcumin, as a potential natural anti-inflammatory compound, are promising compounds for cancer treatment. This study aimed to synthesize a novel imidazo[1,2-a]pyridine derivative, (MIA), and evaluate its anti-inflammatory activity and effects on nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways, and their target genes, alone and in combination with curcumin, in MDA-MB-231 and SKOV3 cell lines.

Methods

We evaluated the interaction between imidazo[1,2-a]pyridine ligand, curcumin, and NF-κB p50 protein, using molecular docking studies. MTT assay was used to investigate the impacts of compounds on cell viability. To evaluate the NF-κB DNA binding activity and the level of inflammatory cytokines in response to the compounds, ELISA-based methods were performed. In addition, quantitative polymerase chain reaction (qPCR) and western blotting were carried out to analyze the expression of genes and investigate NF-κB and STAT3 signaling pathways.

Results

Molecular docking studies showed that MIA docked into the NF-κB p50 subunit, and curcumin augmented its binding. The MTT assay results indicated that MIA and its combination with curcumin reduced cell viability. According to the results of the ELISA-based methods, MIA lowered the levels of inflammatory cytokines and suppressed NF-κB activity. In addition, real-time PCR and Griess test results showed that the expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) genes, and nitrite production were reduced by MIA. Furthermore, the western blotting analysis demonstrated that MIA increased the expression of inhibitory κB (IκBα) and B-cell lymphoma 2 (Bcl-2)-associated X proteins (BAX), and suppressed the STAT3 phosphorylation, and Bcl-2 expression. Our findings revealed that curcumin had a potentiating role and enhanced all the anti-inflammatory effects of MIA.

Conclusion

This study indicated that the anti-inflammatory activity of MIA is exerted by suppressing the NF-κB and STAT3 signaling pathways in MDA-MB-231 and SKOV3 cancer cell lines.

Potential Therapeutic Targets of Quercetin in the Cutaneous Melanoma Model and Its Cellular Regulation Pathways: A Systematic Review

Melanoma is a skin cancer with a high mortality rate due to its invasive characteristics. Currently, immunotherapy and targeted therapy increase patient survival but are ineffective in the advanced stages of the tumor. Quercetin (Que) is a natural compound that has demonstrated chemopreventive effects against different types of tumors. This review provides evidence for the therapeutic potential of Que in melanoma and identifies its main targets. The Scopus, Web of Science, and PubMed databases were searched, and studies that used free or encapsulated Que in melanoma models were included, excluding associations, analogs, and extracts. As a result, 73 articles were retrieved and their data extracted. Que has multiple cellular targets in melanoma models, and the main regulated pathways are cell death, redox metabolism, metastasis, and melanization. Que was also able to regulate important targets of signaling pathways, such as PKC, RIG-I, STAT, and P53. In murine models, treatment with Que reduced tumor growth and weight, and decreased metastatic nodules and angiogenic vasculature. Several studies have incorporated Que into carriers, demonstrating improved efficacy and delivery to tumors. Thus, Que is a promising therapeutic agent for the treatment of melanoma; however, further studies are needed to evaluate its effectiveness in clinical trials.

Phloretin-induced STAT3 inhibition suppresses pancreatic cancer growth and progression via enhancing Nrf2 activity

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a malignant pancreatic tumor charactered by a rapid progression and high lethal rate. Hyperactivation of STAT3 signaling exerts a vital effect on the growth and progression of PDAC. While dietary flavonoid phloretin has anti-inflammatory and antioxidant activities, it remains unclear whether phloretin has anti-tumor effects on PDAC.

PURPOSE

The focus of the present study is to elucidate the effects of phloretin on PDAC and investigate its underlying molecular mechanisms.

STUDY DESIGN AND METHODS

Effect of phloretin were assessed in the pancreatic cancer cells (PCCs) by colony formation assay, real-time cell analysis, flow cytometry, Immunofluorescence staining, and cell migration assay. The expressions of mRNA and protein were respectively analyzed by quantitative PCR and Western blotting. A xenograft model was used to appraise the antitumor efficacy of phloretin.

RESULTS

Phloretin treatment significantly restrained cell viability and metastasis, induced DNA injury and ROS accumulation, and triggered mitochondrial-dependent apoptosis in PCCs. Mechanistically, phloretin exhibits anti-tumor potential via inactivating STAT3 signaling and enhancing Nrf2 activity. STAT3 overexpression and Nrf2 silencing partially relieved phloretin-induced inhibition on cell growth and metastasis in PCCs. Phloretin remarkably blocked pancreatic tumor growth and metastasis in vivo.

CONCLUSIONS

Phloretin suppresses pancreatic cancer growth and progression through inhibition of STAT3 mediated by enhancing Nrf2 activity. Phloretin may serve as a promising therapeutic agent for PDAC.

Lung cancer treatment potential and limits associated with the STAT family of transcription factors

Lung cancer is one of the mortal cancers and the leading cause of cancer-related mortality, with a cancer survival rate of fewer than 5% in developing nations. This low survival rate can be linked to things like late-stage detection, quick postoperative recurrences in patients receiving therapy, and chemoresistance developing against various lung cancer treatments. Signal transducer and activator of transcription (STAT) family of transcription factors are involved in lung cancer cell proliferation, metastasis, immunological control, and treatment resistance. By interacting with specific DNA sequences, STAT proteins trigger the production of particular genes, which in turn result in adaptive and incredibly specific biological responses. In the human genome, seven STAT proteins have been discovered (STAT1 to STAT6, including STAT5a and STAT5b). Many external signaling proteins can activate unphosphorylated STATs (uSTATs), which are found inactively in the cytoplasm. When STAT proteins are activated, they can increase the transcription of several target genes, which leads to unchecked cellular proliferation, anti-apoptotic reactions, and angiogenesis. The effects of STAT transcription factors on lung cancer are variable; some are either pro- or anti-tumorigenic, while others maintain dual, context-dependent activities. Here, we give a succinct summary of the various functions that each member of the STAT family plays in lung cancer and go into more detail about the advantages and disadvantages of pharmacologically targeting STAT proteins and their upstream activators in the context of lung cancer treatment.

Acacetin exerts antitumor effects on gastric cancer by targeting EGFR

Background: Gastric cancer (GC) is a common malignant tumor with a poor prognosis. Combination treatments may prolong the survival of patients with GC. Acacetin, which is a flavonoid, exerts potent inhibitory effects on several types of cancer cells; however, the mechanisms of action remain poorly understood. Methods: Network pharmacology and RNA sequencing were used to predict the targets of acacetin, which were then verified by drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA) and molecular docking. The biological functions of acacetin in MKN45 and MGC803 cells were investigated using TUNEL assays, crystal staining and colony formation assays. The pathways affected by acacetin were verified through reverse experiments. The in vivo antitumor efficacy of acacetin was assessed in a subcutaneous xenotransplanted tumor model. Results: In this study, we identified EGFR from more than a dozen predicted targets as a protein that directly binds to acacetin. Moreover, acacetin affected the level of phosphorylated EGFR. In vitro, acacetin promoted the apoptosis of GC cells. Importantly, EGFR agonists reversed the inhibitory effects of acacetin on the STAT3 and ERK pathways. In vivo, acacetin decreased the protein levels of pEGFR in tumors, resulting in increased GC xenograft tumor regression without obvious toxicity. Conclusion: Our findings highlight EGFR as one of the direct targets of acacetin in GC cells. Acacetin inhibited the phosphatase activity of EGFR in vitro and in vivo, which played a role in the antitumor effects of acacetin. These studies provide new evidence for the use of acacetin as a potential reagent for the treatment of GC.

Targeting FGFRs Using PD173074 as a Novel Therapeutic Strategy in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an architecturally complex tumour with high heterogeneity. Discovery at later stages makes treatment challenging. However, the lack of early detection methodologies and the asymptomatic nature of CCA make early diagnosis more difficult. Recent studies revealed the fusions in Fibroblast Growth Factor Receptors (FGFRs), a sub-family of RTKs, as promising targets for targeted therapy for CCA. Particularly, FGFR2 fusions have been of particular interest, as translocations have been found in approximately 13% of CCA patients. Pursuing this, Pemigatinib, a small-molecule inhibitor of FGFR, became the first targeted therapy drug to be granted accelerated approval by the FDA for treating CCA patients harbouring FGFR2 fusions who have failed first-line chemotherapy. However, despite the availability of Pemigatinib, a very limited group of patients benefit from this treatment. Moreover, as the underlying mechanism of FGFR signalling is poorly elucidated in CCA, therapeutic inhibitors designed to inhibit this pathway are prone to primary and acquired resistance, as witnessed amongst other Tyrosine Kinase Inhibitors (TKIs). While acknowledging the limited cohort that benefits from FGFR inhibitors, and the poorly elucidated mechanism of the FGFR pathway, we sought to characterise the potential of FGFR inhibitors in CCA patients without FGFR2 fusions. Here we demonstrate aberrant FGFR expression in CCA samples using bioinformatics and further confirm phosphorylated-FGFR expression in paraffinised CCA tissues using immunohistochemistry. Our results highlight p-FGFR as a biomarker to guide FGFR-targeted therapies. Furthermore, CCA cell lines with FGFR expression were sensitive to a selective pan-FGFR inhibitor, PD173074, suggesting that this drug can be used to suppress CCA cells irrespective of the FGFR2 fusions. Finally, the correlation analysis utilising publicly available cohorts suggested the possibility of crosstalk amongst the FGFR and EGFR family of receptors as they are significantly co-expressed. Accordingly, dual inhibition of FGFRs and EGFR by PD173074 and EGFR inhibitor erlotinib was synergistic in CCA. Hence, the findings from this study provide support for further clinical investigation of PD173074, as well as other FGFR inhibitors, to benefit a larger cohort of patients. Altogether, this study shows for the first time the potential of FGFRs and the importance of dual inhibition as a novel therapeutic strategy in CCA.

Neuroprotective Effects of Ecklonia cava in a Chronic Neuroinflammatory Disease Model

Inflammation is a natural defense mechanism against noxious stimuli, but chronic inflammation can lead to various chronic diseases. Neuroinflammation in the central nervous system plays an important role in the development and progression of neurodegenerative diseases. Polyphenol-rich natural products, such as Ecklonia cava (E. cava), are known to have anti-inflammatory and antioxidant properties and can provide treatment strategies for neurodegenerative diseases by controlling neuroinflammation. We investigated the effects of an E. cava extract on neuroinflammation and neurodegeneration under chronic inflammatory conditions. Mice were pretreated with E. cava extract for 19 days and then exposed to E. cava with lipopolysaccharide (LPS) for 1 week. We monitored pro-inflammatory cytokines levels in the serum, inflammation-related markers, and neurodegenerative markers using Western blotting and qRT-PCR in the mouse cerebrum and hippocampus. E. cava reduced pro-inflammatory cytokine levels in the blood and brain of mice with LPS-induced chronic inflammation. We also measured the activity of genes related to neuroinflammation and neurodegeneration. Surprisingly, E. cava decreased the activity of markers associated with inflammation (NF-kB and STAT3) and a neurodegenerative disease marker (glial fibrillary acidic protein, beta-amyloid) in the cerebrum and hippocampus of mice. We suggest that E. cava extract has the potential as a protective agent against neuroinflammation and neurodegenerative diseases.

Deciphering STAT3 signaling potential in hepatocellular carcinoma: tumorigenesis, treatment resistance, and pharmacological significance

Hepatocellular carcinoma (HCC) is considered one of the greatest challenges to human life and is the most common form of liver cancer. Treatment of HCC depends on chemotherapy, radiotherapy, surgery, and immunotherapy, all of which have their own drawbacks, and patients may develop resistance to these therapies due to the aggressive behavior of HCC cells. New and effective therapies for HCC can be developed by targeting molecular signaling pathways. The expression of signal transducer and activator of transcription 3 (STAT3) in human cancer cells changes, and during cancer progression, the expression tends to increase. After induction of STAT3 signaling by growth factors and cytokines, STAT3 is phosphorylated and translocated to the nucleus to regulate cancer progression. The concept of the current review revolves around the expression and phosphorylation status of STAT3 in HCC, and studies show that the expression of STAT3 is high during the progression of HCC. This review addresses the function of STAT3 as an oncogenic factor in HCC, as STAT3 is able to prevent apoptosis and thus promote the progression of HCC. Moreover, STAT3 regulates both survival- and death-inducing autophagy in HCC and promotes cancer metastasis by inducing the epithelial-mesenchymal transition (EMT). In addition, upregulation of STAT3 is associated with the occurrence of chemoresistance and radioresistance in HCC. Specifically, non-protein-coding transcripts regulate STAT3 signaling in HCC, and their inhibition by antitumor agents may affect tumor progression. In this review, all these topics are discussed in detail to provide further insight into the role of STAT3 in tumorigenesis, treatment resistance, and pharmacological regulation of HCC.

FOXK1 regulates epithelial-mesenchymal transition and radiation sensitivity in nasopharyngeal carcinoma via the JAK/STAT3 signaling pathway

BACKGROUND

Nasopharyngeal carcinoma (NPC) is the most common head and neck tumor in China. Forkhead box (FOX) proteins have 19 subfamilies, which can maintain cell metabolism, regulate cell cycle and cell growth, etc. FOXK1 is a member of the FOX family, and studies have found that FOXK1 is closely related to tumors.

OBJECTIVE

This experiment aims to study the effects of FOXK1 interference on proliferation, apoptosis, invasion, epithelial-mesenchymal transition (EMT), and radiosensitivity, by regulating the Janus kinas/signal translator and activator of the transfer 3 (JAK/STAT3) pathway.

METHODS

The expression of FOXK1 was detected via immunohistochemistry using clinical nasopharyngeal carcinoma tissues and adjacent tissues. The relationship between FOXK1 expression and tumor stage was subsequently evaluated. The colony formation rate was calculated through the colony formation experiment. Cell apoptosis and cell cycle distribution were detected using flow cytometry, while cell invasion was detected using the Transwell method. The number of cells in the nucleus of each group after 30 min, 4 h, and 24 h of radiotherapy with the 2 Gy dose was counted using immunofluorescence under γ-H2AX focal points of a laser confocal microscope.

RESULTS

FOXK1 is clearly expressed in the patients' cancer tissues. The expression of FOXK1 was significantly correlated with the patient's sex. FOXK1 interference or Peficitinib can upregulate the apoptosis rate of 5-8 F and CNE-2 cells; increase the G2 phase of cells; and inhibit the invasion, migration, and EMT of cells. At the same time, FOXK1 interference can downregulate the protein expression of p-JAK1, p-JAK2, and p-STAT3 in cells. Interference from FOXK1 or Peficitinib alone can reduce the rate of cell colony formation under different radiation doses, and enhance the green fluorescence intensity of γ-H2AX in the nucleus after 4 and 24 h of the 2 Gy dose of radiotherapy. These results are optimal when FOXK1 interference and Peficitinib are used together.

CONCLUSION

FOXK1 interference in NPC cells can regulate EMT through the JAK/STAT3 signal pathway, enhance the radiosensitivity of cells, and thus inhibit tumor cell progression.

Epigenetic programing of cancer stemness by transcription factors-non-coding RNAs interactions

Cancer 'stemness' is fundamental to cancer existence. It defines the ability of cancer cells to indefinitely perpetuate as well as differentiate. Cancer stem cell populations within a growing tumor also help evade the inhibitory effects of chemo- as well as radiation-therapies, in addition to playing an important role in cancer metastases. NF-κB and STAT-3 are representative transcription factors (TFs) that have long been associated with cancer stemness, thus presenting as attractive targets for cancer therapy. The growing interest in non-coding RNAs (ncRNAs) in the recent years has provided further insight into the mechanisms by which TFs influence cancer stem cell characteristics. There is evidence for a direct regulation of TFs by ncRNAs, such as, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) as well as circular RNAs (circRNAs), and vice versa. Additionally, the TF-ncRNAs regulations are often indirect, involving ncRNA-target genes or the sponging of other ncRNA species by individual ncRNAs. The information is rapidly evolving and this review provides a comprehensive review of TF-ncRNAs interactions with implications on cancer stemness and in response to therapies. Such knowledge will help uncover the many levels of tight regulations that control cancer stemness, providing novel opportunities and targets for therapy in the process.

Combined therapeutic effect of YHO-1701 with PD-1 blockade is dependent on natural killer cell activity in syngeneic mouse models

The signal transducer and activator of transcription 3 (STAT3) signaling pathway is a key mediator of cancer cell proliferation, survival, and invasion. We discovered YHO-1701 as a small molecule inhibitor of STAT3 dimerization and demonstrated its potent anti-tumor activity using xenograft mouse models as monotherapy and combination therapy with molecular targeted drugs. STAT3 is also associated with cancer immune tolerance; therefore, we used the female CT26 syngeneic mouse model to examine the effect of combining YHO-1701 administration with PD-1/PD-L1 blockade. Pretreatment of the mice with YHO-1701 before starting anti-PD-1 antibody administration resulted in a significant therapeutic effect. In addition, the effect of monotherapy and combination treatment with YHO-1701 was significantly abolished by depleting natural killer (NK) cell activity. YHO-1701 was also found to restore the activity of mouse NK cells under inhibitory conditions in vitro. Furthermore, this combination therapy significantly inhibited tumor growth in an immunotherapy-resistant model of murine CMS5a fibrosarcoma. These results suggest that the combination of YHO-1701 with PD-1/PD-L1 blockade might be a new candidate for cancer immunotherapy involving the enhancement of NK cell activity in the tumor microenvironment.

Synergistic effect of chrysin and radiotherapy against triple-negative breast cancer (TNBC) cell lines

PURPOSE

Triple-negative breast cancer (TNBC) is the most aggressive form of breast cancer, accounting for 20% of cases. Due to the lack of a molecular target, limited options are available for TNBC treatment. Radiation therapy (RT) is a treatment modality for the management of TNBC following surgery; however, it has a detrimental effect on surrounding healthy tissues/cells at a higher rate.

METHODS

We examined the effect of RT in combination with chrysin as a possible radiosensitizing agent in an MDA-MB-231 cell line as a model of a TNBC. The growth inhibitory effects of chrysin were examined using an MTT assay. Flow cytometry was performed to evaluate apoptosis and expression of hypoxia-induced factor-1α (HIF-1α). The protein expression of p-STAT3/STAT3 and Cyclin D1 was examined using western blotting. Real-time PCR determined apoptotic-related genes (Bax, BCL2, p53).

RESULTS

Treatment of MDA-MB-231 cells with chrysin in combination with RT caused synergistic antitumor effects, with an optimum combination index (CI) of 0.495. Our results indicated that chrysin synergistically potentiated RT-induced apoptosis in MDA-MB-231 compared with monotherapies (chrysin and/or RT alone). Expression of HIF-1α was decreased in the cells exposed to combinational therapy. The apoptotic effect of combinational therapy was correlated with increased Bax (pro-apoptotic gene) and p53 levels along with reduced expression of Bcl-2 (anti-apoptotic gene). Increased apoptosis was associated with reduced expression of Cyclin D1, p-STAT3.

CONCLUSION

These findings highlight the potential effect of chrysin as a radiosensitizer, indicating the synergistic anti-cancer effect of chrysin and RT in TNBC. Further investigation is warranted in this regard.

Novel Insights into RAD52’s Structure, Function, and Druggability for Synthetic Lethality and Innovative Anticancer Therapies

In recent years, the RAD52 protein has been highlighted as a mediator of many DNA repair mechanisms. While RAD52 was initially considered to be a non-essential auxiliary factor, its inhibition has more recently been demonstrated to be synthetically lethal in cancer cells bearing mutations and inactivation of specific intracellular pathways, such as homologous recombination. RAD52 is now recognized as a novel and critical pharmacological target. In this review, we comprehensively describe the available structural and functional information on RAD52. The review highlights the pathways in which RAD52 is involved and the approaches to RAD52 inhibition. We discuss the multifaceted role of this protein, which has a complex, dynamic, and functional 3D superstructural arrangement. This complexity reinforces the need to further investigate and characterize RAD52 to solve a challenging mechanistic puzzle and pave the way for a robust drug discovery campaign.

Deoxynivalenol hijacks the pathway of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT-3) to drive caspase-3-mediated apoptosis in intestinal porcine epithelial cells

Deoxynivalenol (DON) can easily injure the intestinal tract, which represents the first barrier against food contaminants. The intestinal toxicity induced by DON was mainly focused on mitogen-activated protein kinase (MAPK) activation, however, the underlying mechanisms by which DON triggers apoptosis by other pathways remain poorly understood. In this study, the Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT-3) pathway was proposed to regulate the intrinsic apoptosis induced by DON and thoroughly investigated in intestinal porcine epithelial cells (IPEC-J2). First, DON was found to be able to efficiently inhibit cell viability and increase the release of lactate dehydrogenase. It could also enhance the activity of the cleaved caspase-3 in a time-dependent manner, accompanied by a loss of mitochondrial membrane potential and an up-regulation of the apoptosis rate. Then, the expression of genes associated with inflammation and apoptosis were investigated. DON increased the expression of IL-6, IL-1β, TNF-α, SOCS3 and Bax, but decreased the expression of Bcl-2 and Bcl-xL. Moreover, we discovered that DON robustly inhibited STAT-3 activity together with the down-regulation of JAK2, Bcl-2 and Bcl-xL, paralleling the increase in p38 phosphorylation. Furthermore, a pharmacological activation of JAK2/STAT-3 alleviated DON induced-apoptosis. Concurrent with the apoptotic pathway, during the initial exposure to DON (first 4 h), a survival pathway involving phosphorylated Erk1/2, Akt, and FoxO1 was also observed. Thus, apoptosis induced by DON was Janus faced: although the survival pathway was activated, the DON-induced apoptotic JAK2/STAT-3/caspase-3 pathway dominated, leading to an imbalance in cell homeostasis. This study provides a novel avenue to comprehensively reveal the pathological mechanisms of DON-induced intestinal disorders, which is promising for future applications to other contaminants in food and feed.

Putative Role of Neutrophil Extracellular Trap Formation in Chronic Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are hematologic malignancies characterized by gene mutations that promote myeloproliferation and resistance to apoptosis via constitutively active signaling pathways, with Janus kinase 2-signal transducers and the activators of transcription (JAK-STAT) axis as a core part. Chronic inflammation has been described as a pivot for the development and advancement of MPNs from early stage cancer to pronounced bone marrow fibrosis, but there are still unresolved questions regarding this issue. The MPN neutrophils are characterized by upregulation of JAK target genes, they are in a state of activation and with deregulated apoptotic machinery. Deregulated neutrophil apoptotic cell death supports inflammation and steers them towards secondary necrosis or neutrophil extracellular trap (NET) formation, a trigger of inflammation both ways. NETs in proinflammatory bone marrow microenvironment induce hematopoietic precursor proliferation, which has an impact on hematopoietic disorders. In MPNs, neutrophils are primed for NET formation, and even though it seems obvious for NETs to intervene in the disease progression by supporting inflammation, no reliable data are available. We discuss in this review the potential pathophysiological relevance of NET formation in MPNs, with the intention of contributing to a better understanding of how neutrophils and neutrophil clonality can orchestrate the evolution of a pathological microenvironment in MPNs.

GDF15 Promotes Cell Growth, Migration, and Invasion in Gastric Cancer by Inducing STAT3 Activation

Growth differentiation factor 15 (GDF15) has been reported to play an important role in cancer and is secreted and involved in the progression of various cancers, including ovarian cancer, prostate cancer, and thyroid cancer. Nevertheless, the functional mechanism of GDF15 in gastric cancer is still unclear. Immunohistochemical staining was performed to estimate the expression of GDF15 in 178 gastric cancer tissues. The biological role and action mechanism of GDF15 were investigated by examining the effect of GDF15 knockdown in AGS and SNU216 gastric cancer cells. Here, we report that the high expression of GDF15 was associated with invasion depth (p = 0.002), nodal involvement (p = 0.003), stage III/IV (p = 0.01), lymphatic invasion (p = 0.05), and tumor size (p = 0.049), which are related to poor survival in gastric cancer patients. GDF15 knockdown induced G0/G1 cell cycle arrest and remarkably inhibited cell proliferation and reduced cell motility, migration, and invasion compared to the control. GDF15 knockdown inhibited the epithelial-mesenchymal transition by regulating the STAT3 phosphorylation signaling pathways. Taken together, our results indicate that GDF15 expression is associated with aggressive gastric cancer by promoting STAT3 phosphorylation, suggesting that the GDF15-STAT3 signaling axis is a potential therapeutic target against gastric cancer progression.

Cisplatin or Doxorubicin Reduces Cell Viability via the PTPIVA3-JAK2-STAT3 Cascade in Hepatocellular Carcinoma

Introduction

Hepatocellular carcinoma (HCC) accounts for 80% of all liver cancers and is the 2nd leading cause of cancer-related death in Taiwan. Various factors, including rapid cell growth, a high recurrence rate and drug resistance, make HCC difficult to cure. Moreover, the survival rate of advanced HCC patients treated with systemic chemotherapy remains unsatisfactory. Hence, the identification of novel molecular targets and the underlying mechanisms of chemoresistance in HCC and the development more effective therapeutic regimens are desperately needed.

Methods

An MTT assay was used to determine the cell viability after cisplatin or doxorubicin treatment. Western blotting, qRT‒PCR and immunohistochemistry were utilized to examine the protein tyrosine phosphatase IVA3 (PTP4A3) level and associated signaling pathways. ELISA was utilized to analyze the levels of the inflammatory cytokine IL-6 influenced by cisplatin, doxorubicin and PTP4A3 silencing.

Results

In this study, we found that PTP4A3 in the cisplatin/doxorubicin-resistant microarray was closely associated with the overall and recurrence-free survival rates of HCC patients. Cisplatin or doxorubicin significantly reduced cell viability and decreased PTP4A3 expression in hepatoma cells. IL-6 secretion increased with cisplatin or doxorubicin treatment and after PTP4A3 silencing. Furthermore, PTP4A3 was highly expressed in tumor tissues versus adjacent normal tissues from HCC patients. In addition, we evaluated the IL-6-associated signaling pathway involving STAT3 and JAK2, and the levels of p-STAT3, p-JAK2, STAT3 and JAK2 were obviously reduced with cisplatin or doxorubicin treatment in HCC cells using Western blotting and were also decreased after silencing PTP4A3. Collectively, we suggest that cisplatin or doxorubicin decreases HCC cell viability via downregulation of PTP4A3 expression through the IL-6R-JAK2-STAT3 cascade.

Discussion

Therefore, emerging evidence provides a deep understanding of the roles of PTP4A3 in HCC cisplatin/doxorubicin chemoresistance, which can be applied to develop early diagnosis strategies and reveal prognostic factors to establish novel targeted therapeutics to specifically treat HCC.

Gracillin exerts anti-melanoma effects in vitro and in vivo: role of DNA damage, apoptosis and autophagy

BACKGROUND

Melanoma is an aggressive cancer. Gracillin has been reported to treat various types of cancer, such as colorectal and lung cancer. However, there is a paucity of research on the anti-melanoma effects of gracillin.

PURPOSE

The aim of this study was to assess the anti-melanoma effects and mechanisms of action of gracillin in vitro and in vivo.

METHODS

Cell viability was detected using MTT and crystal violet staining assays. Cell proliferation was examined by EdU staining assays. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Autophagic flux was monitored under a confocal microscope. Protein levels were determined by immunoblotting. LY294002 and rapamycin (Rapa) were used to determine the involvement of PI3K/AKT/mTOR signaling in gracillin-mediated autophagy. Signal transducer and activator of transcription 3 (STAT3) was overactivated to explore the contribution of the STAT3 signaling pathway in the anti-melanoma effects of gracillin. A B16F10 allograft mouse model was developed to evaluate the anti-melanoma effects of gracillin in vivo.

RESULTS

We demonstrated that in melanoma cells, gracillin inhibited proliferation, induced G0/G1 phase cell cycle arrest, evoked apoptosis, and triggered autophagic cell death. Gracillin induced DNA damage in melanoma cells. Moreover, it suppressed the phosphorylation/activation of PI3K, AKT, mTOR, and 4E-BP1 in melanoma cells. Inhibiting PI3K/AKT and mTOR activity using LY294002 and Rapa, respectively, increased the protein level of LC3B-II in gracillin-treated melanoma cells. Furthermore, gracillin downregulated the protein levels of p-JAK2 (Tyr1007/1008), p-Src (Tyr416), and p-STAT3 (Tyr705) in melanoma cells. Over-expression of STAT3 in A375 cells significantly mitigated the cytotoxic and apoptotic effects of gracillin. In vivo studies showed that gracillin (1 mg/kg or 8 mg/kg, administered intraperitoneally for 16 consecutive days) suppressed B16F10 tumor growth and Src/STAT3 and AKT/mTOR signaling in tumors. No overt toxicity was observed in mice.

CONCLUSION

Induction of DNA damage, inhibition of PI3K/AKT/mTOR signaling and suppression of STAT3 signaling are involved in gracillin-mediated cell cycle arrest, autophagic cell death and apoptosis, respectively, in melanoma cells. These findings provide novel insights into the anti-melanoma molecular mechanisms of gracillin, and suggest a potential role of gracillin in melanoma management.

In vitro anti-cancer effects of beauvericin through inhibition of actin polymerization and Src phosphorylation

BACKGROUND

Beauvericin (BEA) is a depsipeptide with antimicrobial, anti-inflammatory, and anti-cancer activities isolated from Beauveria bassiana. However, little is understood on its anti-cancer activities and mechanism.

PURPOSE

Aim of this study was to explore the anti-cancer activity of BEA and its underlying molecular mechanism to provide a theoretical basis for its role as a candidate natural drug in cancer diseases.

STUDY DESIGN

Various cancer cells such as C6 glioma, U251, MDA-MB-231, HeLa, HCT-15, LoVo cells, and HEK293T cells were used to the anti-cancer activity of BEA.

METHODS

To evaluate the anti-cancer activity of BEA, cell viability test (MTT assay), morphological change check, confocal microscopy, actin polymerization assay, flow cytometry, and Western blotting analysis. To check the target enzyme of BEA, overexpression and site-directed mutagenesis was employed.

RESULTS

BEA inhibited the viability of cancer cells including C6, MDA-MB-231, HeLa, HCT-15, LoVo, and U251 cells. Treatment of BEA in C6 glioma cells induced cell membrane blebbing and apoptosis. Caspase-3 and -9 were dose-dependently activated by BEA, and the mRNA expression of Bcl-2 was inhibited by BEA. According to confocal microscopy, actin polymerization and actin-actin interaction were interrupted by BEA in C6 cells. BEA regulated the apoptosis of C6 cells depending on the protein phosphorylation of Src and Signal transducer and activator of transcription (STAT3). Moreover, c-terminal amino acids in Src directly interacted with BEA in C6 cells, and the binding of Src and BEA suppressed the kinase activity of Src.

CONCLUSIONS

These results suggest that BEA may be a critical candidate or substitute drug for cancer treatment via suppression of the Src/STAT3 pathway.

Biological Role and Mechanism of Lipid Metabolism Reprogramming Related Gene ECHS1 in Cancer

Cancer is a major threat to human health today. Although the existing anticancer treatments have effectively improved the prognosis of some patients, there are still other patients who cannot benefit from these well-established strategies. Reprogramming of lipid metabolism is one of the typical features of cancers. Recent studies have revealed that key enzymes involved in lipid metabolism may be effective anticancer therapeutic targets, but the development of therapeutic lipid metabolism targets is still insufficient. ECHS1 (enoyl-CoA hydratase, short chain 1) is a key enzyme mediating the hydration process of mitochondrial fatty acid β-oxidation and has been observed to be abnormally expressed in a variety of cancers. Therefore, with ECHS1 and cancer as the main keywords, we searched the relevant studies of ECHS1 in the field of cancer in Pubmed, summarized the research status and functions of ECHS1 in different cancer contexts, and explored its potential regulatory mechanisms, with a view to finding new therapeutic targets for anti-metabolic therapy. By reviewing and summarizing the retrieved literatures, we found that ECHS1 regulates malignant biological behaviors such as cell proliferation, metastasis, apoptosis, autophagy, and drug resistance by remodeling lipid metabolism and regulating intercellular oncogenic signaling pathways. Not only that, ECHS1 exhibits early diagnostic and prognostic value in clear cell renal cell carcinoma, and small-molecule inhibitors that regulate ECHS1 also show therapeutic significance in preclinical studies. Taken together, we propose that ECHS1 has the potential to serve as a therapeutic target of lipid metabolism.

Ciclopirox drives growth arrest and autophagic cell death through STAT3 in gastric cancer cells

Ciclopirox (CPX), an antifungal drug, has recently been identified as a promising agent for cancer treatment. However, the effects and underlying mechanism of CPX as an antitumor agent of gastric cancer (GC) remain largely unknown. Here, we found that CPX dramatically suppresses GC xenograft growth in vitro via inhibiting proliferation and stimulating autophagic cell death rather than apoptosis. Moreover, CPX (20 mg/kg, intraperitoneally) substantially inhibits GC xenograft tumor growth in vivo. Mechanistically, CPX promotes growth arrest and autophagic cell death through suppressing the phosphorylation of signal transducers and activators of transcription 3 (STAT3) at tyrosine 705 (Tyr705) and serine 727 (Ser727) sites, respectively. Additionally, CPX induces STAT3 ubiquitination, which subsequently leads to a decrease in the p-STAT3 (Ser727) level. On the other hand, CPX represses the p-STAT3 (Tyr705) level via p-Src (Tyr416) inhibition. Collectively, our findings unmask a novel mechanism by which CPX regulates growth and autophagic cell death in GC cells via regulating the phosphorylation of STAT3 both at Tyr705 and Ser727 residues, and suggest that CPX may be a potential treatment for GC.

Nanotherapeutics for immune network modulation in tumor microenvironments

Immunotherapy has shown promise in cancer treatment, and is thus drawing increasing interest in this field. While the standard chemotherapy- and/or radiotherapy-based cancer treatments aim to directly kill cancer cells, immunotherapy uses host immune cell surveillance to fight cancer. In the tumor environment, there is a close relationship between tumor cells and the adjacent immune cells, which are largely suppressed by cancer-related regulation of immune checkpoints, immune-suppressive cytokines, and metabolic factors. The immune modulators currently approved for cancer treatment remain limited by issues with dose tolerance and insufficient efficacy. Researchers have developed and tested various nano-delivery systems with the goal of improving the treatment outcome of these drugs. By encapsulating immune modulators in particles and directing their tissue accumulation, some such systems have decreased immune-related toxicity while sharpening the antitumor response. Surface-ligand modification of nanoparticles has allowed drugs to be delivered to specific immune cells types. Researchers have also studied strategies for depleting or reprogramming the immune-suppressive cells to recover the immune environment. Combining a nanomaterial with an external stimulus has been used to induce immunogenic cell death; this favors the inflammatory environment found in tumor tissues to promote antitumor immunity. The present review covers the most recent strategies aimed at modulating the tumor immune environment, and discusses the challenges and future perspectives in developing nanoparticles for cancer immunotherapy.