Taxifolin inhibits melanoma proliferation/migration impeding USP18/Rac1/JNK/ß-catenin oncogenic signaling.

BACKGROUND: Metastatic melanoma is a fatal cancer. Despite the advances in targeted therapy and immunotherapy for patients with melanoma, drug resistance and low response rates pose a considerable challenge. Taxifolin is a multifunctional natural compound with emerging antitumor potentials. However, its utility in melanoma treatment remains unclear. PURPOSE: The study aimed to investigate the effect of purified Taxifolin from Larix olgensis roots (Changbai Mountain, China) on melanoma and explore the underlying mechanism. METHODS: Purified Taxifolin from Larix olgensis roots was evaluated for its antimelanoma effects in vitro and in vivo settings. RNA-seq analysis was performed to explore the underlying mechanism. RESULTS: Purified Taxifolin (> 99 %) from Larix olgensis roots inhibited the proliferation and migration of B16F10 melanoma cells at 200 and 400 µM, and of A375 cells at 100 and 200 µM. Taxifolin administered at 60 mg/kg suppressed tumor growth and metastasis in mouse models without causing significant toxicity. Taxifolin modulated USP18/Rac1/JNK/ß-catenin axis to exert its antitumor effect. CONCLUSION: These findings indicate that Taxifolin derived from Larix olgensis roots may be a promising antimelanoma therapy.

Histone chaperone SSRP1 is required for apoptosis inhibition and mitochondrial function in HCC via transcriptional promotion of TRAP1.

Epigenetic regulation contributes to human health and disease, especially cancer, but the mechanisms of many epigenetic regulators remain obscure. Most research is focused on gene regulatory processes, such as mRNA translation and DNA damage repair, rather than the effects on biological functions like mitochondrial activity and oxidative phosphorylation. Here, we identified an essential role for the histone chaperone structure-specific recognition protein 1 (SSRP1) in mitochondrial oxidative respiration in hepatocellular carcinoma, and found that SSRP1 suppression led to mitochondrial damage and decreased oxidative respiration. Further, we focused on TNF receptor-associated protein 1 (TRAP1), the only member of the heat shock protein 90 (HSP90) family, which directly interacts with selected respiratory complexes and affects their stability and activity. We confirmed that SSRP1 downregulation caused a decrease in TRAP1 expression at both the mRNA and protein levels. A chromatin immunoprecipitation assay also showed that SSRP1 could deposit in the TRAP1 promoter region, indicating that SSRP1 maintains mitochondrial function and reactive oxygen species levels through TRAP1. Additionally, rescue experiments and animal experiments confirmed the mechanism of SSRP1 and TRAP1 interaction. In summary, we identified a new mechanism that connects mitochondrial respiration and apoptosis, via SSRP1.

Stat3 shRNA delivery with folate receptor-modified multi-functionalized graphene oxide particles for combined infrared radiation and gene therapy in hepatocellular carcinoma.

As a vital oncogene, a variety of inhibitors targeting Stat3 and its various upstream signaling pathways has been explored. Since small molecules, peptidomimetics and other peptide inhibitors usually lead to side effects and difficult administration, gene therapeutics that have characteristics of low toxicity and high targeting, make them an attractive alternative for targeting Stat3. A major challenge to this approach is the lack of safe delivery systems for in-vivo applications. Among the various siRNA delivery systems, nanoparticles emerge as a new tool for gene delivery with high biocompatibility, low cost, and minimal toxicity. In this study, we developed a graphene oxide (GO)-based nanocarrier, GO-polyethyleneimine (PEI)-polyethylene glycol (PEG)-folic acid (FA), as a tool targeting for Stat3-specific shRNA to mouse hepatoma cells in vitro and in vivo . Infrared photothermal therapy was combined in vivo since GO has the characteristic of infrared absorbability. Our results suggest a significant tumor growth inhibition after treatment with GO-PEI-PEG-FA- sh-Stat3 combined with infrared photothermal therapy. Thus, GO-PEI-PEG-FA appears to be a novel nano-transformer that could be used in the clinics in future.

A photodynamically sensitized dendritic cell vaccine that promotes the anti-tumor effects of anti-PD-L1 monoclonal antibody in a murine model of head and neck squamous cell carcinoma.

BACKGROUND: Immune checkpoint inhibitors are promising tools in combating several cancers, including head and neck squamous cell carcinoma (HNSCC). However, a substantial portion of HNSCC patients do not respond to PD-L1 antibody. Here we describe a photodynamic therapeutic (PDT) approach to enhance anti-tumor effects of the anti-PD-L1 antibody. METHODS: Phototoxicity of PDT was confirmed using fluorescence microscopy, Cell Counting Kit-8 (CCK-8), Enzyme Linked Immunosorbent Assay (ELISA) and flow cytometry analyses. Phenotypic and functional maturation of immature DCs (imDCs) induced by PDT were measured using flow cytometry and ELISA. A mouse model was established using the HNSCC line, SCC7, and was used to evaluate therapeutic effects of PDT-DC vaccine in facilitating anti-tumor immunity of PD-L1 antibody. RESULTS: Immunogenic cell death (ICD) of SCC7 cells was induced by PDT with 0.5 µM of m-THPC and the 5 J/cm2 of light dose. ICD of SCC7 cells stimulated imDCs maturation. In vivo assays suggested that PDT-DC vaccine and anti-PD-L1 mAb synergistically induced anti-tumor immunity and suppressed tumor progression. CONCLUSION: PDT-DC vaccine enhances therapeutic effects of PD-L1 antibody, which might provide a novel approach for HNSCC immunotherapy.

RSL3 triggers glioma stem cell differentiation via the Tgm2/AKT/ID1 signaling axis.

RSL3 is a synthetic molecule that inactivates glutathione peroxidase 4 to induce ferroptosis. However, its effect on glioma stem cells (GSC) remains unclear. In this study, we found that RSL3 significantly suppressed GSC proliferation and induced their differentiation into astrocytes, which was accompanied by the downregulation of stemness-related markers, including Nestin and Sox2. Combined transcriptome and proteome analyses further revealed that RSL3 promoted GSC differentiation by suppressing transglutaminase 2 (Tgm2), but not by ferroptosis-related pathways. Tgm2 overexpression in CSC2078 cells rescued the changes in stemness-related markers and differentiation caused by RSL3, which was mediated by inhibitor of DNA binding 1 (ID1) activation. Further studies identified ID1 as a downstream signaling target of Tgm2. Blocking the phosphoinositide-3 kinase (PI3K)/Akt pathway with LY294002 suppressed PI3K, p-Akt, and ID1 levels but not Tgm2. Tgm2 overexpression abrogated the changes in PI3K, p-Akt, and ID1 levels caused by LY294002. Taken together, we demonstrate that RSL3 does not induce ferroptosis; instead, it inhibits GSC proliferation and triggers their differentiation by suppressing the Tgm2/Akt/ID1 signaling axis.

Epigenetic regulation of cancer stem cells: Shedding light on the refractory/relapsed cancers.

The resistance to drugs, ability to enter quiescence and generate heterogeneous cancer cells, and enhancement of aggressiveness, make cancer stem cells (CSCs) integral part of tumor progression, metastasis and recurrence after treatment. The epigenetic modification machinery is crucial for the viability of CSCs and evolution of aggressive forms of a tumor. These mechanisms can also be targeted by specific drugs, providing a promising approach for blocking CSCs. In this review, we summarize the epigenetic regulatory mechanisms in CSCs which contribute to drug resistance, quiescence and tumor heterogeneity. We also discuss the drugs that can potentially target these processes and data from experimental and clinical studies.

Roles for the methyltransferase SETD8 in DNA damage repair.

Epigenetic posttranslational modifications are critical for fine-tuning gene expression in various biological processes. SETD8 is so far the only known lysyl methyltransferase in mammalian cells to produce mono-methylation of histone H4 at lysine 20 (H4K20me1), a prerequisite for di- and tri-methylation. Importantly, SETD8 is related to a number of cellular activities, impinging upon tissue development, senescence and tumorigenesis. The double-strand breaks (DSBs) are cytotoxic DNA damages with deleterious consequences, such as genomic instability and cancer origin, if unrepaired. The homology-directed repair and canonical nonhomologous end-joining are two most prominent DSB repair pathways evolved to eliminate such aberrations. Emerging evidence implies that SETD8 and its corresponding H4K20 methylation are relevant to establishment of DSB repair pathway choice. Understanding how SETD8 functions in DSB repair pathway choice will shed light on the molecular basis of SETD8-deficiency related disorders and will be valuable for the development of new treatments. In this review, we discuss the progress made to date in roles for the lysine mono-methyltransferase SETD8 in DNA damage repair and its therapeutic relevance, in particular illuminating its involvement in establishment of DSB repair pathway choice, which is crucial for the timely elimination of DSBs.

GRIM-19 inhibits proliferation and induces apoptosis in a p53-dependent manner in colorectal cancer cells through the SIRT7/PCAF/MDM2 axis.

Colorectal cancer (CRC) is the leading deadly cancer worldwide. Gene associated with retinoid-IFN-induced mortality-19 (GRIM-19), a novel tumor suppressor, has been reported to be expressed at low levels in human CRC. However, the role of GRIM-19 in CRC progression and the corresponding detailed mechanisms are unclear. The results of this study indicated that GRIM-19 expression is related to CRC progression. Overexpression of GRIM-19 was found to inhibit CRC cell proliferation and induce apoptosis in vitro and in vivo. Our results demonstrated that GRIM-19 suppresses CRC through posttranslational regulation of p53, in which SIRT7 is activated by GRIM-19 and triggers PCAF-mediated MDM2 ubiquitination, eventually stabilizing the p53 protein. We also observed that GRIM-19 enhances the effect of oxaliplatin against CRC. In conclusion, GRIM-19 plays an important role in CRC development and is a potential biomarker and therapeutic target for clinical treatment of CRC.

Perspectives on Oncolytic Salmonella in Cancer Immunotherapy-A Promising Strategy.

Since the first reported spontaneous regression of tumors in patients with streptococcus infection, cancer biological therapy was born and it evolved into today's immunotherapy over the last century. Although the original strategy was unable to impart maximal therapeutic benefit at the beginning, it laid the foundations for the development of immune checkpoint blockade and CAR-T which are currently used for cancer treatment in the clinics. However, clinical applications have shown that current cancer immunotherapy can cause a series of adverse reactions and are captious for patients with preexisting autoimmune disorders. Salmonellae was first reported to exert antitumor effect in 1935. Until now, numerous studies have proved its potency as an antitumor agent in the near future. In this review, we summarize the currently available data on the antitumor effects of Salmonella, and discussed a possibility of integrating Salmonella into cancer immunotherapy to overcome current obstacles.

A Combination of BRD4 and HDAC3 Inhibitors Synergistically Suppresses Glioma Stem Cell Growth by Blocking GLI1/IL6/STAT3 Signaling Axis.

Glioma stem cells (GSC) are essential for tumor maintenance, invasiveness, and recurrence. Using a global epigenetic screening with an shRNA library, we identified HDAC3 as an essential factor for GSC stemness. Here, we demonstrated that GSCs poorly respond to an HDAC3 inhibitor, RGFP966 (HDAC3i), owing to the production of IL6 and STAT3 activation. To enhance GSC sensitivity to HDAC3i, we explored whether cotreatment with a BRD4 inhibitor, JQ1 (BRD4i), in GSCs produced a better antitumor effect. BRD4i synergistically inhibits GSC growth in association with HDAC3i. HDAC3 inhibition upregulated the acetylation of H3K27, which allowed the recruitment of BRD4 to the GLI1 gene promoter and induced its expression. GLI1, a transcription factor, turned on the expression of IL6, which led to the activation of STAT3 signaling pathways. However, BRD4i inhibited transcription of the GLI1 gene, thereby blocking the GLI1/IL6/STAT3 pathway. In vivo, the HDAC3i/BRD4i combination caused stronger tumor growth suppression than either drug alone. Thus, HDAC3i/BRD4i might provide promising therapies for GBM.

RGFP966, a histone deacetylase 3 inhibitor, promotes glioma stem cell differentiation by blocking TGF-ß signaling via SMAD7.

Glioma stem cells (GSC) play a major role in drug resistance and tumor recurrence. Using a genetic screen with a set of shRNAs that can target chromatin regulators in a GSC model, we have HDAC3 as a major negative regulator of GSC differentiation. Inhibition of HDAC3 using a pharmacological inhibitor or a siRNA led to the induction of GSC differentiation into astrocytes. Consequently, HDAC3-inhibition also caused a strong reduction of tumor-promoting and self-renewal capabilities of GSCs. These phenotypes were highly associated with an increased acetylation of SMAD7, which protected its ubiquitination. SMAD7 inhibits a TGF-ß signaling axis that is required for maintaining stemness. These results demonstrate that HDAC3 appears to be a proper target in anti-glioma therapy.

Nonviral Delivery of GRIM-19 Gene Inhibits Tumor Growth with Reduced Local and Systemic Complications.

Chemotherapy causes inflammation, which promotes cancer development and results in complications such as hemorrhages and thrombosis. Development of new therapeutic strategies to limit inflammatory responses will potentially reduce these side effects in cancer patients. Gene therapy is an attractive cancer treatment because of its high specificity and limited side effects. A tumor suppressor gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) was delivered by an amphiphilic copolymer poly(ɛ-caprolactone) and ethanolamine-functionalized poly (glycidyl methacrylate) (PCG). The transfection outcome of PCG/pGRIM-19 complexes was studied both in vitro and in vivo. The antitumor therapeutic effects were evaluated in a well-vascularized Neuro-2a neuroblastoma tumor mouse model in comparison with that of cisplatin. The PCG/pGRIM-19 nanocomplex showed high transfection efficiency and low toxicity. In vitro transfection of PCG/pGRIM-19 in Neuro-2a cells reduced the expression levels of Cyclin D1, BCL-2, and MMPs 2 and 9, and inhibited cell proliferation, migration, and stimulated apoptosis. In vivo experiments indicated that PCG/pGRIM-19 therapy downregulated signal transducer activator of transcription 3, nuclear factor-κB, and MMP9 expression in tumor tissues. Compared with cisplatin treatment, gene therapy with PCG/pGRIM-19 significantly inhibited local complications of intratumor hemorrhages, and systemic complications such as anemia and pulmonary embolism, thereby effectively prolonged mouse survival. Our results highlight the potential of PCG/pGRIM-19 gene therapy in reducing tumor burden and complications, providing novel strategies to enhance clinical cancer therapy.

IL-33 contributes to disease severity in Psoriasis-like models of mouse.

Immune cells infiltrating the psoriatic skin secrete high amounts of pro-inflammatory cytokines IL-17, TNF-α, IL-21 and IL-36 resulting in chronic inflammation. However, the exact cellular and molecular mechanisms have not been fully understood. We report here elevation of IL-33 expression in psoriatic lesions. Studies in imiquimod (IMQ)-induced mice with psoriatic inflammation confirmed a critical role for IL-33 in driving the disease. IL-33 reduces the CD4+ and CD8+ cells, inhibits autophagy in IMQ-treated mouse skin, and promoted tyrosyl phosphorylation of STAT3. Thus, IL-33 appears to be a major risk factor for severity of psoriasis-like skin inflammation. Our findings may open new perspectives for understanding the mechanisms and developing a therapeutic strategy for psoriasis.

Editorial: Cytokines in liver diseases.

This special issue on 'Cytokines in Liver Diseases' was inspired by many talks and presentations on liver cancer during the 2nd Aegean Conference on Cytokine Signaling in Cancer (ACCSC) held at Heraklion, Crete, Greece on May 30-June 04, 2017 (Cytokine 2018, 108: 225-231). The liver is the biggest blood filtration and detoxification unit, and is a vital metabolic organ. Being constantly exposed to potentially harmful dietary chemicals, drugs, alcohol abuse and pathogens, the liver displays an extraordinary capacity to repair tissue damage and to regenerate. Moreover, only a healthy liver can provide the vast majority of plasma proteins, plus serving as a key organ for body homeostasis and metabolic fitness. Occasionally, the liver may have to deal with chronic damage inflicted by hepatotropic infections such as hepatitis viruses and metabolic derangements caused by obesity and the consequent metabolic syndrome. Overwhelming the natural defenses of the liver can compromise its vital functions and this can lead to more severe liver disease such as fibrosis that may progress towards cirrhosis and eventually to hepatocellular carcinoma (HCC). However, in obesity, a worldwide crisis that has been developing during the last few decades, HCC can develop in the fatty liver bypassing the fibrosis and cirrhosis stages. With the availability of effective therapies and vaccination strategies for hepatitis viruses, over nutrition has become the biggest new threat for a healthy liver. Cytokines and chemokines play a key role in the initiation and perpetuation of acute and chronic injury to the liver, and thus they contribute to most liver pathologies. The topic of cytokines in liver diseases is so vast that it cannot be adequately covered in this special issue. However, we have attempted to provide a glimpse of hot topics through comprehensive reviews and a few accompanying original articles on key research areas.

Immortalization of Murine Bone Marrow-Derived Macrophages.

Macrophages are specialized phagocytes that display a variety of important functions for the host immune system. They are particularly important for the recognition of exogenous and endogenous danger signals, forming the defensive front line as part of innate immune response. As such, murine macrophages are commonly used for in vitro cell-based assays examining the mechanisms of innate immune activation, which can require the ongoing breeding and housing of a large number of genetically modified mouse strains. Here, we describe a robust protocol for the generation of immortalized bone marrow-derived macrophages (iBMDMs) from primary murine bone marrow cells. We further provide general protocols for harvesting, freezing, and thawing of bone marrow cells, maintaining iBMDMs in culture and generation of monoclonal iBMDM populations by single-cell cloning.

Oncosuppressor protein p53 and cyclin-dependent kinase inhibitor p21 regulate interstitial cystitis associated gene expression.

Interstitial cystitis (IC) is a chronic syndrome that affects the urinary bladder. The etiology of this disease is unclear, and no effective therapies are available at this time. Although inflammation is suspected, no clear evidence for a role of conventional mediators of inflammation, such as cytokines and their downstream molecules, has been obtained to date. Our previous studies indicated that primary cell cultures derived from IC urothelium abnormally express molecules associated with cell adhesion. Here we describe a mechanism by which transcriptional changes in tight junction and adhesion molecules are mediated. Oncosuppressor proteins p53 and cyclin-dependent protein kinase inhibitor p21 directly associate with regulatory sites on the ZO-1 and E-cadherin genes, identifying important roles for p53 and p21 in driving non-oncogenic pathologies. These data also suggest that interference with these factors offers a potential therapeutic opportunity.

Meeting summary: 2nd Aegean Conference on Cytokine Signaling in Cancer.

Cytokines and chemokines are intricately connected to cancer initiation, progression and metastasis as well as to innate and adaptive host defense mechanisms against transformed cells. The Aegean Conference on Cytokine Signaling in Cancer (ACCSC) aims to bring together researchers in this highly targeted area of cancer research in a lovely and relaxing Greek-Mediterranean backdrop to discuss latest developments. Being small in size with about one hundred participants, this conference fosters scientific and social interactions among established and emerging scientists in clinical and basic research in diverse fields of oncology, biochemistry, biophysics, genetics and immunology. The 2nd ACCSC held at Heraklion on the Greek island of Crete was organized by Serge Fuchs (University of Pennsylvania), Mathias Muller (University of Veterinary Medicine Vienna), Leonidas Platanias (Northwestern University, Chicago) and Belinda Parker (La Trobe University, Melbourne) between May 30 and June 04, 2017, was a great success in every single aspect of a high level scientific meeting. Signaling within cancer cells as well as in stromal and immune cells is the common thread of this conference series. An outline of the research topics discussed at this conference is presented here to emphasize its high quality and to stimulate interest among cytokine researchers to participate in future ACCSC meetings.