Small Non-Coding RNAs in Soft-Tissue Sarcomas: State of the Art and Future Directions

Soft-tissue sarcomas (STS) are a rare and heterogeneous group of tumors that arise from connective tissue and can occur anywhere in the body. Among the plethora of over 50 different STS types, liposarcoma (LPS) is one of the most common. The subtypes of STS are characterized by distinct differences in tumor biology that drive responses to pharmacologic therapy and disparate oncologic outcomes. Small non-coding RNAs (sncRNA) are a heterogeneous class of regulatory RNAs involved in the regulation of gene expression by targeting mRNAs. Among the several types of sncRNAs, miRNAs and tRNA-derived ncRNAs are the most studied in the context of tumor biology, and we are learning more about the role of these molecules as important regulators of STS tumorigenesis and differentiation. However, challenges remain in translating these findings and no biomarkers or therapeutic approaches targeting sncRNAs have been developed for clinical use. In this review, we summarize the current landscape of sncRNAs in the context of STS with an emphasis on LPS, including the role of sncRNAs in the tumorigenesis and differentiation of these rare malignancies and their potential as novel biomarkers and therapeutic targets. Finally, we provide an appraisal of published studies and outline future directions to study sncRNAs in STS, including tRNA-derived ncRNAs.

Phosphorylation of IWS1 by AKT maintains liposarcoma tumor heterogeneity through preservation of cancer stem cell phenotypes and mesenchymal-epithelial plasticity

Chemotherapy remains the mainstay of treatment for patients with advanced liposarcoma (LPS), but response rates are only 25% and the overall survival at 5 years is dismal at 20-34%. Translation of other therapies have not been successful and there has been no significant improvement in prognosis for nearly 20 years. The aberrant activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway has been implicated in the aggressive clinical behavior LPS and in resistance to chemotherapy, but the precise mechanism remains elusive and efforts to target AKT clinically have failed. Here we show that the AKT-mediated phosphorylation of the transcription elongation factor IWS1, promotes the maintenance of cancer stem cells in both cell and xenograft models of LPS. In addition, phosphorylation of IWS1 by AKT contributes to a "metastable" cell phenotype, characterized by mesenchymal/epithelial plasticity. The expression of phosphorylated IWS1 also promotes anchorage-dependent and independent growth, cell migration, invasion, and tumor metastasis. In patients with LPS, IWS1 expression is associated with reduced overall survival, increased frequency of recurrence, and shorter time to relapse after resection. These findings indicate that IWS1-mediated transcription elongation is an important regulator of human LPS pathobiology in an AKT-dependent manner and implicate IWS1 as an important molecular target to treat LPS.

The Skin-Whitening and Antioxidant Effects of Protocatechuic Acid (PCA) Derivatives in Melanoma and Fibroblast Cell Lines

The skin is the most voluminous organ of the human body and is exposed to the outer environment. Such exposed skin suffers from the effects of various intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, and skin pigmentation. Skin pigmentation occurs in skin aging and is caused by hyper-melanogenesis and oxidative stress. Protocatechuic acid (PCA) is a natural secondary metabolite from a plant-based source widely used as a cosmetic ingredient. We chemically designed and synthesized PCA derivatives conjugated with alkyl esters to develop effective chemicals that have skin-whitening and antioxidant effects and enhance the pharmacological activities of PCA. We identified that melanin biosynthesis in B16 melanoma cells treated with alpha-melanocyte-stimulating hormone (α-MSH) is decreased by PCA derivatives. We also found that PCA derivatives effectively have antioxidant effects in HS68 fibroblast cells. In this study, we suggest that our PCA derivatives are potent ingredients for developing cosmetics with skin-whitening and antioxidant effects.

Methylsulfonylmethane relieves cobalt chloride-induced hypoxic toxicity in C2C12 myoblasts

AIMS

In biology and medicine, hypoxia refers to reduced oxygen tension or oxygen starvation resulting from various environmental or pathological conditions. Prolonged hypoxia may lead to an imbalance in protein production and a loss of muscle mass in animals. The physiological response to hypoxia includes oxidative stress-induced activation of complex cell-signaling networks such as hypoxia-inducible factor (HIF), phosphoinositide 3-kinase (PI3K), and Janus kinase/signal transducer and activator of transcription (JAK-STAT). Methylsulfonylmethane (MSM) is a natural sulfur compound that regulates HIF-1α expression and provides cytoprotection from oxidative stress. In this study, we explored the anti-hypoxic activity and cytoprotective effect of MSM in cobalt chloride (CoCl₂)-induced hypoxic C2C12 mouse myoblast culture.

MATERIALS AND METHODS

We used western blotting, real time PCR, flow cytometry for molecular signaling studies and we also used MTT assay and ChIP assay along with comet assay for cellular processes.

KEY FINDINGS

MSM prevented the CoCl₂ induced cytotoxicity. Molecular markers of hypoxia, induced by CoCl₂, were normalized or reduced by MSM, which also inhibited the effect of CoCl₂-induced JAK2/STAT5b/Cyclin D1 and PI3K/AKT signaling. CoCl₂-induced oxidative stress results in activation of the NRF2/HO-1-mediated cell survival pathway and inhibition of DNA repair, both of which were prevented by MSM.

SIGNIFICANCE

We suggest MSM can be considered as a candidate drug for reducing the effects of hypoxia in both animals and humans.

Pivotal Role of Iron Homeostasis in the Induction of Mitochondrial Apoptosis by 6-Gingerol Through PTEN Regulated PD-L1 Expression in Embryonic Cancer Cells

Embryonic cancer stem cells (CSCs) can differentiate into any cancer type. Targeting CSCs with natural compounds is a promising approach as it suppresses cancer recurrence with fewer adverse effects. 6-Gingerol is an active component of ginger, which exhibits well-known anti-cancer activities. This study determined the mechanistic aspects of cell death induction by 6-gingerol. To analyze cellular processes, we used Western blot and real-time qPCR for molecular signaling studies and conducted flow cytometry. Our results suggested an inhibition of CSC marker expression and Wnt/β-catenin signaling by 6-gingerol in NCCIT and NTERA-2 cells. 6-Gingerol induced reactive oxygen species generation, the DNA damage response, cell cycle arrest, and the intrinsic pathway of apoptosis in embryonic CSCs. Furthermore, 6-gingerol inhibited iron metabolism and induced PTEN, which both played vital roles in the induction of cell death. The activation of PTEN resulted in the inhibition of PD-L1 expression through PI3K/AKT/p53 signaling. The induction of PTEN also mediated the downregulation of microRNAs miR-20b, miR-21, and miR-130b to result in PD-L1 suppression by 6-gingerol. Hence, 6-gingerol may be a promising candidate to target CSCs by regulating PTEN-mediated PD-L1 expression.

Iron Metabolism as a Potential Mechanism for Inducing TRAIL-Mediated Extrinsic Apoptosis Using Methylsulfonylmethane in Embryonic Cancer Stem Cells

Embryonic cancer stem cells (CSCs) can differentiate into any cancer type. Targeting CSC using natural compounds is a good approach as it suppresses cancer recurrence with fewer adverse effects, and methylsulfonylmethane (MSM) is a sulfur-containing compound with well-known anticancer activities. This study determined the mechanistic aspects of the anticancer activity of MSM. We used Western blotting and real-time qPCR for molecular signaling studies and conducted flow cytometry for analyzing the processes in cells. Our results suggested an inhibition in the expression of CSC markers and Wnt/β-catenin signaling. MSM induced TRAIL-mediated extrinsic apoptosis in NCCIT and NTERA-2 cells rather than an intrinsic pathway. Inhibition of iron metabolism-dependent reactive oxygen species (ROS) generation takes part in TRAIL-mediated apoptosis induction by MSM. Suppressing iron metabolism by MSM also regulated p38/p53/ERK signaling and microRNA expressions, such as upregulating miR-130a and downregulating miR-221 and miR-222, which resulted in TRAIL induction and thereby extrinsic pathway of apoptosis. Hence, MSM could be a good candidate for neoadjuvant therapy by targeting CSCs by inhibiting iron metabolism.

New Insights into the Pivotal Role of Iron/Heme Metabolism in TLR4/NF-κB Signaling-Mediated Inflammatory Responses in Human Monocytes

Iron metabolism and heme biosynthesis are essential processes in cells during the energy cycle. Alteration in these processes could create an inflammatory condition, which results in tumorigenesis. Studies are conducted on the exact role of iron/heme metabolism in induced inflammatory conditions. This study used lipopolysaccharide (LPS)- or high-glucose-induced inflammation conditions in THP-1 cells to study how iron/heme metabolism participates in inflammatory responses. Here, we used iron and heme assays for measuring total iron and heme. We also used flow cytometry and Western blotting to analyze molecular responses. Our results demonstrated that adding LPS or high-glucose induced iron formation and heme synthesis and elevated the expression levels of proteins responsible for iron metabolism and heme synthesis. We then found that further addition of heme or 5-aminolevulinic acid (ALA) increased heme biosynthesis and promoted inflammatory responses by upregulating TLR4/NF-κB and inflammatory cytokine expressions. We also demonstrated the inhibition of heme synthesis using succinylacetone (SA). Moreover, N-MMP inhibited LPS- or high-glucose-induced inflammatory responses by inhibiting TLR4/NF-κB signaling. Hence, iron/heme metabolism checkpoints could be considered a target for treating inflammatory conditions.

Applications and Functions of γ-Poly-Glutamic Acid and its Derivatives in Medicine

BACKGROUND

γ-Poly-Glutamic Acid (γ-PGA) is a naturally occurring homo-polyamide produced by various strains of Bacillus. It is made from repeating units of L-glutamic acid, D-glutamic acid, or both connected through amide linkages between α-amino and γ-carboxylic acid groups. As a biopolymer substance, the attractive properties of γ-PGA are that it is water-soluble, biodegradable, biocompatible, non-toxic, non-immunogenic, and edible. Therefore, it can be used as a green and environmentally friendly biological material.

METHODS

The review concentrates on the reports revealing the functions and potential use of γ-PGA and its derivatives in medicine.

RESULTS & DISCUSSION

γ-PGA is described to possess several properties that may be exploited in medicine. The biopolymer reportedly has been successfully applied not only as a metal chelator, drug carrier/ deliverer, and gene vector, but also used safely as a vaccine adjuvant, tissue engineering material, and contrast agent.

CONCLUSION

γ-PGA could be potentially considered as a potential biomedical material in the field of medicine.

Silibinin Regulates Tumor Progression and Tumorsphere Formation by Suppressing PD-L1 Expression in Non-Small Cell Lung Cancer (NSCLC) Cells

Recently, natural compounds have been used globally for cancer treatment studies. Silibinin is a natural compound extracted from Silybum marianum (milk thistle), which has been suggested as an anticancer drug through various studies. Studies on its activity in various cancers are undergoing. This study demonstrated the molecular signaling behind the anticancer activity of silibinin in non-small cell lung cancer (NSCLC). Quantitative real-time polymerase chain reaction and Western blotting analysis were performed for molecular signaling analysis. Wound healing assay, invasion assay, and in vitro angiogenesis were performed for the anticancer activity of silibinin. The results indicated that silibinin inhibited A549, H292, and H460 cell proliferation in a concentration-dependent manner, as confirmed by the induction of G0/G1 cell cycle arrest and apoptosis and the inhibition of tumor angiogenesis, migration, and invasion. This study also assessed the role of silibinin in suppressing tumorsphere formation using the tumorsphere formation assay. By binding to the epidermal growth factor receptor (EGFR), silibinin downregulated phosphorylated EGFR expression, which then inhibited its downstream targets, the JAK2/STAT5 and PI3K/AKT pathways, and thereby reduced matrix metalloproteinase, PD-L1, and vascular endothelial growth factor expression. Binding analysis demonstrated that STAT5 binds to the PD-L1 promoter region in the nucleus and silibinin inhibited the STAT5/PD-L1 complex. Altogether, silibinin could be considered as a candidate for tumor immunotherapy and cancer stem cell-targeted therapy.

Natural Sulfurs Inhibit LPS-Induced Inflammatory Responses through NF-κB Signaling in CCD-986Sk Skin Fibroblasts

Lipopolysaccharide (LPS)-induced inflammatory response leads to serious damage, up to and including tumorigenesis. Natural mineral sulfur, non-toxic sulfur (NTS), and methylsulfonylmethane (MSM) have anti-inflammatory activity that may inhibit LPS-induced inflammation. We hypothesized that sulfur compounds could inhibit LPS-induced inflammatory responses in CCD-986Sk skin fibroblasts. We used Western blotting and real-time PCR to analyze molecular signaling in treated and untreated cultures. We also used flow cytometry for cell surface receptor analysis, comet assays to evaluate DNA damage, and ELISA-based cytokine detection. LPS induced TLR4 activation and NF-κB signaling via canonical and protein kinase C (PKC)-dependent pathways, while NTS and MSM downregulated that response. NTS and MSM also inhibited LPS-induced nuclear accumulation and binding of NF-κB to proinflammatory cytokines COX-2, IL-1β, and IL-6. Finally, the sulfur compounds suppressed LPS-induced ROS accumulation and DNA damage in CCD-986Sk cells. These results suggest that natural sulfur compounds could be used to treat inflammation and may be useful in the development of cosmetics.

Potential Antitumor Effects of 6-Gingerol in p53-Dependent Mitochondrial Apoptosis and Inhibition of Tumor Sphere Formation in Breast Cancer Cells

Hormone-specific anticancer drugs for breast cancer treatment can cause serious side effects. Thus, treatment with natural compounds has been considered a better approach as this minimizes side effects and has multiple targets. 6-Gingerol is an active polyphenol in ginger with various modalities, including anticancer activity, although its mechanism of action remains unknown. Increases in the level of reactive oxygen species (ROS) can lead to DNA damage and the induction of DNA damage response (DDR) mechanism, leading to cell cycle arrest apoptosis and tumorsphere suppression. Epidermal growth factor receptor (EGFR) promotes tumor growth by stimulating signaling of downstream targets that in turn activates tumor protein 53 (p53) to promote apoptosis. Here we assessed the effect of 6-gingerol treatment on MDA-MB-231 and MCF-7 breast cancer cell lines. 6-Gingerol induced cellular and mitochondrial ROS that elevated DDR through ataxia-telangiectasia mutated and p53 activation. 6-Gingerol also induced G0/G1 cell cycle arrest and mitochondrial apoptosis by mediating the BAX/BCL-2 ratio and release of cytochrome c. It also exhibited a suppression ability of tumorsphere formation in breast cancer cells. EGFR/Src/STAT3 signaling was also determined to be responsible for p53 activation and that 6-gingerol induced p53-dependent intrinsic apoptosis in breast cancer cells. Therefore, 6-gingerol may be used as a candidate drug against hormone-dependent breast cancer cells.

Non-toxic sulfur inhibits LPS-induced inflammation by regulating TLR-4 and JAK2/STAT3 through IL-6 signaling

Janus kinase 2 (JAK2) and STAT3 signaling is considered a major pathway in lipopolysaccharide (LPS)‑induced inflammation. Toll‑like receptor 4 (TLR‑4) is an inflammatory response receptor that activates JAK2 during inflammation. STAT3 is a transcription factor for the pro‑inflammatory cytokine IL‑6 in inflammation. Sulfur is an essential element in the amino acids and is required for growth and development. Non‑toxic sulfur (NTS) can be used in livestock feeds as it lacks toxicity. The present study aimed to inhibit LPS‑induced inflammation in C2C12 myoblasts using NTS by regulating TLR‑4 and JAK2/STAT3 signaling via the modulation of IL‑6. The 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay was conducted to analyze cell viability and reverse transcription polymerase chain reaction and western blotting performed to measure mRNA and protein expression levels. Chromatin immunoprecipitation and enzyme‑linked immunosorbent assays were used to determine the binding activity of proteins. The results indicated that NTS demonstrated a protective effect against LPS‑induced cell death and inhibited LPS‑induced expression of TLR‑4, JAK2, STAT3 and IL‑6. In addition, NTS inhibited the expression of nuclear phosphorylated‑STAT3 and its binding to the IL‑6 promoter. Therefore, NTS may be a potential candidate drug for the treatment of inflammation.

Antitumor Effects of Ursolic Acid through Mediating the Inhibition of STAT3/PD-L1 Signaling in Non-Small Cell Lung Cancer Cells

Targeted therapy based on natural compounds is one of the best approaches against non-small cell lung cancer. Ursolic acid (UA), a pentacyclic triterpenoid derived from medicinal herbs, has anticancer activity. Studies on the molecular mechanism underlying UA’s anticancer activity are ongoing. Here, we demonstrated UA’s anticancer activity and the underlying signaling mechanisms. We used Western blotting and real-time quantitative polymerase chain reaction for molecular signaling analysis. We also used in vitro angiogenesis, wound healing, and invasion assays to study UA’s anticancer activity. In addition, we used tumorsphere formation and chromatin immunoprecipitation assays for binding studies. The results showed that UA inhibited the proliferation of A549 and H460 cells in a concentration-dependent manner. UA exerted anticancer effects by inducing G0/G1 cell cycle arrest and apoptosis. It also inhibited tumor angiogenesis, migration, invasion, and tumorsphere formation. The molecular mechanism underlying UA activity involves UA’s binding to epidermal growth factor receptor (EGFR), reducing the level of phospho-EGFR, and thus inhibiting the downstream JAK2/STAT3 pathway. Furthermore, UA reduced the expressions of vascular endothelial growth factor (VEGF), metalloproteinases (MMPs) and programmed death ligand-1 (PD-L1), as well as the formation of STAT3/MMP2 and STAT3/PD-L1 complexes. Altogether, UA exhibits anticancer activities by inhibiting MMP2 and PD-L1 expression through EGFR/JAK2/STAT3 signaling.

Methylsulfonylmethane Induces Cell Cycle Arrest and Apoptosis, and Suppresses the Stemness Potential of HT-29 Cells

BACKGROUND/AIM

Colorectal cancer is one of the most common malignancies worldwide. Small molecule-based chemotherapy is an attractive approach for the chemoprevention and treatment of colorectal cancer. Methylsulfonylmethane (MSM) is a natural organosulfur compound with anticancer properties, as revealed by studies on in vitro models of gingival, prostate, lung, hepatic, and breast cancer. However, the molecular mechanisms underlying the effects of MSM in colon cancer cells remain unclear.

MATERIALS AND METHODS

Here, we investigated the effects of MSM, especially on the cell cycle arrest and apoptosis, in HT-29 cells.

RESULTS

MSM suppressed the viability of HT-29 cells by inducing apoptosis and cell cycle arrest at the G₀/G₁ phase. MSM suppressed the sphere-forming ability and expression of stemness markers in HT-29 cells.

CONCLUSION

MSM has anti-cancer effects on HT-29 cells, and induces cell cycle arrest and apoptosis, while suppressing the stemness potential.

Tannic Acid Inhibits Non-small Cell Lung Cancer (NSCLC) Stemness by Inducing G0/G1 Cell Cycle Arrest and Intrinsic Apoptosis

BACKGROUND/AIM

Non-small cell lung cancer (NSCLC) is one among the most common cancers worldwide. Recently, dietary phytochemicals have been reported as an attractive approach to improve the symptoms of NSCLC patients. Tannic acid is a natural polyphenol, which is known to have anticancer effects on in vitro models of breast, gingival and colon cancer. However, the molecular mechanisms associated with the actions of tannic acid on A549 human lung cancer cells have not been elucidated.

MATERIALS AND METHODS

In this study, we analyzed the effect of tannic acid on A549 cells and their underlying mechanisms using western blotting, flow cytometry, invasion assay and tumorsphere formation assay.

RESULTS

Tannic acid treatment suppressed the viability of A549 cells through cell cycle arrest and induction of the intrinsic pathways of apoptosis. In addition, the various malignant phenotypes of A549 cells including invasion, migration, and stemness were inhibited by tannic acid treatment.

CONCLUSION

Tannic acid could be used as an effective inhibitor of lung cancer progression.

Effect of Methylsulfonylmethane on Proliferation and Apoptosis of A549 Lung Cancer Cells Through G2/M Cell-cycle Arrest and Intrinsic Cell Death Pathway

BACKGROUND/AIM

Methylsulfonylmethane (MSM) is a natural organic compound that displays anti-inflammatory as well as antioxidant properties. MSM reportedly has potential in inhibition of tumor cells. However, molecular mechanisms underlying the effects of MSM on lung cancer remain unclear.

MATERIALS AND METHODS

In this study, the effect of MSM on A549 cells was examined. We focused on the mode of apoptosis induced by MSM and investigated alterations in the integrity of the outer membrane of mitochondria.

RESULTS

Our results showed that MSM inhibited viability of A549 cells and changed the shape and permeability of nuclei. In addition, MSM induced G₂/M arrest. MSM reduced the mitochondrial membrane potential and contributed to release of cytochrome c from mitochondria to cytoplasm.

CONCLUSION

MSM is a potential anticancer agent for the treatment of lung cancer.

The Inhibitory Mechanisms of Tumor PD-L1 Expression by Natural Bioactive Gallic Acid in Non-Small-Cell Lung Cancer (NSCLC) Cells

Non-small-cell lung cancer (NSCLC) is the most common lung cancer subtype and accounts for more than 80% of all lung cancer cases. Epidermal growth factor receptor (EGFR) phosphorylation by binding growth factors such as EGF activates downstream prooncogenic signaling pathways including KRAS-ERK, JAK-STAT, and PI3K-AKT. These pathways promote the tumor progression of NSCLC by inducing uncontrolled cell cycle, proliferation, migration, and programmed death-ligand 1 (PD-L1) expression. New cytotoxic drugs have facilitated considerable progress in NSCLC treatment, but side effects are still a significant cause of mortality. Gallic acid (3,4,5-trihydroxybenzoic acid; GA) is a phenolic natural compound, isolated from plant derivatives, that has been reported to show anticancer effects. We demonstrated the tumor-suppressive effect of GA, which induced the decrease of PD-L1 expression through binding to EGFR in NSCLC. This binding inhibited the phosphorylation of EGFR, subsequently inducing the inhibition of PI3K and AKT phosphorylation, which triggered the activation of p53. The p53-dependent upregulation of miR-34a induced PD-L1 downregulation. Further, we revealed the combination effect of GA and anti-PD-1 monoclonal antibody in an NSCLC-cell and peripheral blood mononuclear-cell coculture system. We propose a novel therapeutic application of GA for immunotherapy and chemotherapy in NSCLC.

A high ATP concentration enhances the cooperative translocation of the SARS coronavirus helicase nsP13 in the unwinding of duplex RNA

Severe acute respiratory syndrome coronavirus nonstructural protein 13 (SCV nsP13), a superfamily 1 helicase, plays a central role in viral RNA replication through the unwinding of duplex RNA and DNA with a 5' single-stranded tail in a 5' to 3' direction. Despite its putative role in viral RNA replication, nsP13 readily unwinds duplex DNA by cooperative translocation. Herein, nsP13 exhibited different characteristics in duplex RNA unwinding than that in duplex DNA. nsP13 showed very poor processivity on duplex RNA compared with that on duplex DNA. More importantly, nsP13 inefficiently unwinds duplex RNA by increasing the 5'-ss tail length. As the concentration of nsP13 increased, the amount of unwound duplex DNA increased and that of unwound duplex RNA decreased. The accumulation of duplex RNA/nsP13 complexes increased as the concentration of nsP13 increased. An increased ATP concentration in the unwinding of duplex RNA relieved the decrease in duplex RNA unwinding. Thus, nsP13 has a strong affinity for duplex RNA as a substrate for the unwinding reaction, which requires increased ATPs to processively unwind duplex RNA. Our results suggest that duplex RNA is a preferred substrate for the helicase activity of nsP13 than duplex DNA at high ATP concentrations.

Validation of exercise-response genes in skeletal muscle cells of Thoroughbred racing horses

Objective

To understand the athletic characteristics of Thoroughbreds, high-throughput analysis has been conducted using horse muscle tissue. However, an in vitro system has been lacking for studying and validating genes from in silico data. The aim of this study is to validate genes from differentially expressed genes (DEGs) of our previous RNA-sequencing data in vitro. Also, we investigated the effects of exercise-induced stress including heat, oxidative, hypoxic and cortisol stress on horse skeletal muscle derived cells with the top six upregulated genes of DEGs.

Methods

Enriched pathway analysis was conducted using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) tool with upregulated genes in horse skeletal muscle tissue after exercise. Among the candidates, the top six genes were analysed through geneMANIA to investigate gene networks. Muscle cells derived from neonatal horse skeletal tissue were maintained and subjected to exercise-related stressors. Transcriptional changes in the top six genes followed by stressors were investigated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

Results

The inflammation response pathway was the most commonly upregulated pathway after horse exercise. Under non-cytotoxic conditions of exercise-related stressors, the transcriptional response of the top six genes was different among types of stress. Oxidative stress yielded the most similar expression pattern to DEGs.

Conclusion

Our results indicate that transcriptional change after horse exercise in skeletal muscle tissue strongly relates to stress response. The qRT-PCR results showed that stressors contribute differently to the transcriptional regulation. These results would be valuable information to understand horse exercise in the stress aspect.

Tannic Acid Promotes TRAIL-Induced Extrinsic Apoptosis by Regulating Mitochondrial ROS in Human Embryonic Carcinoma Cells

: Human embryonic carcinoma (EC; NCCIT) cells have self-renewal ability and pluripotency. Cancer stem cell markers are highly expressed in NCCIT cells, imparting them with the pluripotent nature to differentiate into other cancer types, including breast cancer. As one of the main cancer stem cell pathways, Wnt/β-catenin is also overexpressed in NCCIT cells. Thus, inhibition of these pathways defines the ability of a drug to target cancer stem cells. Tannic acid (TA) is a natural polyphenol present in foods, fruits, and vegetables that has anti-cancer activity. Through Western blotting and PCR, we demonstrate that TA inhibits cancer stem cell markers and the Wnt/β-catenin signaling pathway in NCCIT cells and through a fluorescence-activated cell sorting analysis we demonstrated that TA induces sub-G1 cell cycle arrest and apoptosis. The mechanism underlying this is the induction of mitochondrial reactive oxygen species (ROS) (mROS), which then induce the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated extrinsic apoptosis pathway instead of intrinsic mitochondrial apoptosis pathway. Moreover, ribonucleic acid sequencing data with TA in NCCIT cells show an elevation in TRAIL-induced extrinsic apoptosis, which we confirm by Western blotting and real-time PCR. The induction of human TRAIL also proves that TA can induce extrinsic apoptosis in NCCIT cells by regulating mROS.

Methylsulfonylmethane inhibits cortisol-induced stress through p53-mediated SDHA/HPRT1 expression in racehorse skeletal muscle cells: A primary step against exercise stress

Cortisol is a hormone involved in stress during exercise. The application of natural compounds is a new potential approach for controlling cortisol-induced stress. Tumour suppressor protein p53 is activated during cellular stress. Succinate dehydrogenase complex subunit A (SDHA) and hypoxanthine phosphoribosyl transferase 1 (HPRT1) are considered to be two of the most stable reference genes when measuring stress during exercise in horses. In the present study cells were considered to be in a 'stressed state' if the levels of these stable genes and the highly stress responsive gene p53 were altered. It was hypothesized that a natural organic sulphur-containing compound, methylsulfonylmethane (MSM), could inhibit cortisol-induced stress in racing horse skeletal muscle cells by regulating SDHA, HPRT1 and p53 expression. After assessing cell viability using MTT assays, 20 µg/ml cortisol and 50 mM MSM were applied to horse skeletal muscle cell cultures. Reverse transcription-quantitative PCR and western blot analysis demonstrated increases in SDHA, HPRT1 and p53 expression in cells in response to cortisol treatment, which was inhibited or normalized by MSM treatment. To determine the relationship between p53 and SDHA/HPRT1 expression at a transcriptional level, horse gene sequences of SDHA and HPRT1 were probed to identify novel binding sites for p53 in the gene promoters, which were confirmed using a chromatin immunoprecipitation assay. The relationship between p53 and SDHA/HPRT1 expression was confirmed using western blot analysis following the application of pifithrin-α, a p53 inhibitor. These results suggested that MSM is a potential candidate drug for the inhibition of cortisol-induced stress in racehorse skeletal muscle cells.

Silibinin inhibits in vitro ketosis by regulating HMGCS2 and NF-kB: elucidation of signaling molecule relationship under ketotic conditions

Ketosis is a condition where ketone bodies are produced as an alternative energy source, due to insufficient glucose for energy production so that the body switches from carbohydrate metabolism to mostly fat metabolism. In this study, we examined the anti-ketosis effects of silibinin, a major active component of silymarin. We induced ketosis in FL83B mouse hepatocytes in vitro by culturing in low glucose media and compared results to hepatocytes maintained in high-glucose conditions. We quantified β-hydroxybutyrate (BHB) levels with a colorimetric assay. In low-glucose conditions, silibinin reduced the amount of BHB produced, compared to high-glucose conditions; thus, silibinin exhibited an anti-ketotic effect. Ketone body formation during beta oxidation is mediated by 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2). The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) regulates the transcription of HMGCS2, and plays a vital role in BHB levels. We showed that silibinin inhibited the expression of HMGCS2 and NF-kB at transcriptional and translational levels. Silibinin also inhibited the nuclear translocation of NF-kB and its DNA binding activity. To elucidate the relationship between HMGCS2 and NF-kB, we tested inhibited and over-expressed NF-kB. We found that NF-kB acted as a positive regulator for HMGCS2 under ketosis treatment conditions.

Nobiletin Inhibits CD36-Dependent Tumor Angiogenesis, Migration, Invasion, and Sphere Formation Through the Cd36/Stat3/Nf-Κb Signaling Axis

Targeted cancer therapy with natural compounds is more effective than nontargeted therapy. Nobiletin is a flavonoid derived from citrus peel that has anticancer activity. Cluster of differentiation 36 (CD36) is a member of the class B scavenger receptor family that is involved in importing fatty acids into cells. CD36 plays a role in tumor angiogenesis by binding to its ligand, thrombospondin-1 (TSP-1), and then interacting with transforming growth factor beta 1 (TGFβ1). CD36 is implicated in tumor metastasis through its roles in fatty acid metabolism. This study investigated the molecular mechanisms underlying nobiletin's anticancer activity by characterizing its interactions with CD36 as the target molecule. We hypothesize that the anti-angiogenic activity of nobiletin involving its regulation of CD36 via signal transducer and activator of transcription 3 (STAT3) rather than through TSP-1. Gene analysis identified a Gamma interferon activation site (GAS) element in the CD36 gene promoter that acts as a STAT3 binding site, an interaction that was confirmed by ChIP assay. STAT3 interacts with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), suggesting that nobiletin also acts through the CD36/ (STAT3)/NF-κB signaling axis. Nobiletin inhibited CD36-dependent breast cancer cell migration and invasion as well as CD36-mediated tumor sphere formation. Taken together, these results suggest that nobiletin inhibits cancer stem cells in multiple ways.

Salidroside inhibits migration, invasion and angiogenesis of MDA‑MB 231 TNBC cells by regulating EGFR/Jak2/STAT3 signaling via MMP2

The major hallmarks of tumor progression are angiogenesis, migration and metastasis. Among the components of Rhodiola rosea, salidroside (p‑hydroxyphenethyl-β‑d-glucoside) is one of the most potent, and is present in all Rhodiola species. Recent data have revealed the anticancer effects of salidroside; however, the mechanism underlying its ability to inhibit tumor angiogenesis remains unknown. The present study aimed to analyze how salidroside affects major factors involved in breast cancer, and to elucidate its ability to inhibit angiogenesis and invasion. Signal transducer and activator of transcription 3 (STAT3) is a marker for tumor angiogenesis and migration, which interacts with matrix metalloproteinases (MMPs). Specifically, MMPs act as a downstream target for STAT3. Using western blotting and reverse transcription-quantitative polymerase chain reaction analysis, the present study demonstrated that treatment of MDA‑MB 231 triple-negative breast cancer (TNBC) cells with salidroside led to inhibition of invasion and migration markers, and of STAT3 signaling. Furthermore, in vitro angiogenesis analyses in human umbilical vein endothelial cells confirmed the anti-angiogenic activity of salidroside. An electrophoretic mobility shift assay also demonstrated that salidroside may inhibit the DNA-binding activity of STAT3, preventing STAT3 from binding to a novel binding site of the MMP2 gene promoter. In conclusion, the present results demonstrated that salidroside may downregulate the STAT3 signaling pathway, and inhibit cell viability, migration and invasion through MMPs in breast cancer cells.

Nobiletin Inhibits Angiogenesis by Regulating Src/FAK/STAT3-Mediated Signaling through PXN in ER⁺ Breast Cancer Cells

Tumor angiogenesis is one of the major hallmarks of tumor progression. Nobiletin is a natural flavonoid isolated from citrus peel that has anti-angiogenic activity. Steroid receptor coactivator (Src) is an intracellular tyrosine kinase so that focal adhesion kinase (FAK) binds to Src to play a role in tumor angiogenesis. Signal transducer and activator of transcription 3 (STAT3) is a marker for tumor angiogenesis which interacts with Src. Paxillin (PXN) acts as a downstream target for both FAK and STAT3. The main goal of this study was to assess inhibition of tumor angiogenesis by nobiletin in estrogen receptor positive (ER⁺) breast cancer cells via Src, FAK, and STAT3-mediated signaling through PXN. Treatment with nobiletin in MCF-7 and T47D breast cancer cells inhibited angiogenesis markers, based on western blotting and RT-PCR. Validation of in vitro angiogenesis in the human umbilical vein endothelial cells (HUVEC) endothelial cell line proved the anti-angiogenic activity of nobiletin. Electrophoretic mobility shift assay and the ChIP assay showed that nobiletin inhibits STAT3/DNA binding activity and STAT3 binding to a novel binding site of the PXN gene promoter. We also investigated the migration and invasive ability of nobiletin in ER⁺ cells. Nobiletin inhibited tumor angiogenesis by regulating Src, FAK, and STAT3 signaling through PXN in ER⁺ breast cancer cells.

Silibinin downregulates MMP2 expression via Jak2/STAT3 pathway and inhibits the migration and invasive potential in MDA-MB-231 cells

Worldwide, breast cancer (BCa) is the most common cancer in women. Among its subtypes, triple-negative breast cancer (TNBC) is an aggressive form associated with diminished survival. TNBCs are characterized by their absence, or minimal expression, of the estrogen and progesterone receptors, as well as the human epidermal growth factor receptor 2 (i.e. ER-/-, PR-/-, Her2-/Low). Consequently, treatment for this subtype of BCa remains problematic. Silibinin, a derivative of the flavonoid silymarin, is reported to have anticancer activities against hepatic and non-small cell lung cancers. We hypothesized that silibinin might inhibit cell-extracellular matrix interactions via the regulation, expression, and activation of STAT3 in TNBCs, which could directly inhibit metastasis in silibinin-treated BCa cells. Using proliferation assays, we found that exposure to silibinin at a concentration of 200 µM inhibited the proliferation of breast cancer (BCa) cells; this concentration also inhibited phosphorylation of STAT3 and its principal upstream kinase, Jak2. Furthermore, we found that silibinin inhibited the nuclear translocation of STAT3, as well as its binding to the MMP2 gene promoter. The ability of silibinin to inhibit metastasis was further studied using an in vitro invasion assay. The results confirm the role of STAT3 as a critical mediator in the invasive potential of BCa cells, and STAT3 knock-down resulted in inhibition of invasion. The invasion ability of silibinin-treated BCa cells was studied in detail with the expression of MMP2. Prevention of STAT3 activation also resulted in the inhibition of MMP2 expression. Use of a small interfering RNA to knock down STAT3 (siSTAT3) allowed us to confirm the role of STAT3 in regulating MMP2 expression, as well as the mechanism of action of silibinin in inhibiting MMP2. Taken together, we found that silibinin inhibits the Jak2/STAT3/MMP2 signaling pathway, and inhibits the proliferation, migration, and invasion of triple-negative BCa cells.

Tannic acid inhibits EGFR/STAT1/3 and enhances p38/STAT1 signalling axis in breast cancer cells

Tannic acid (TA), a naturally occurring polyphenol, is a potent anti-oxidant with anti-proliferative effects on multiple cancers. However, its ability to modulate gene-specific expression of tumour suppressor genes and oncogenes has not been assessed. This work investigates the mechanism of TA to regulate canonical and non-canonical STAT pathways to impose the gene-specific induction of G1-arrest and apoptosis. Regardless of the p53 status and membrane receptors, TA induced G1-arrest and apoptosis in breast cancer cells. Tannic acid distinctly modulated both canonical and non-canonical STAT pathways, each with a specific role in TA-induced anti-cancer effects. Tannic acid enhanced STAT1 ser727 phosphorylation via upstream serine kinase p38. This STAT1 ser727 phosphorylation enhanced the DNA-binding activity of STAT1 and in turn enhanced expression of p21^Waf1/Cip1 . However, TA binds to EGF-R and inhibits the tyrosine phosphorylation of both STAT1 and STAT3. This inhibition leads to the inhibition of STAT3/BCL-2 DNA-binding activity. As a result, the expression and mitochondrial localization of BCl-2 are declined. This altered expression and localization of mitochondrial anti-pore factors resulted in the release of cytochrome c and the activation of intrinsic apoptosis cascade involving caspases. Taken together, our results suggest that TA modulates EGF-R/Jak2/STAT1/3 and P38/STAT1/p21^Waf1/Cip1 pathways and induce G1-arrest and intrinsic apoptosis in breast carcinomas.

Methylsulfonylmethane inhibits HER2 expression through STAT5b in breast cancer cells

Breast cancer is the most common cancer in women globally. The factors that increase risk include: late age at first birth, alcohol, radiation exposure, family history of breast cancer, and postmenopausal hormone therapy. Numerous drugs are being developed to treat breast cancer. Among them, Herceptin is used for the treatment of human epidermal growth factor receptor 2 (HER2)-positive cases and targets HER2 effectively and efficiently, but it is very expensive. Methylsulfonylmethane (MSM) is an organic sulfur-containing natural compound having no reported toxicity. We examined MSM in breast cancer cell lines and found it inhibited the proliferation of estrogen receptor-positive and HER2-positive breast cancer cells in a dose-dependent manner. It also suppressed the activation of STAT5b and expression of HER2 in breast cancer cells. We determined the STAT5b binding site (GAS element) in the HER2 gene. Detailed analysis showed that MSM decreased the ability of STAT5b to bind the promoter of the HER2 gene and a luciferase assay demonstrated reduced activity. We confirmed that MSM can effectively regulate STAT5b, and thereby decrease HER2 expression. Therefore, we recommend the use of MSM as an inhibitor for the management of HER2-positive breast cancers.