Antitumor Effects of Natural Bioactive Ursolic Acid in Embryonic Cancer Stem Cells.

Embryonic cancer cells (CSCs) could cause different types of cancer, a skill that makes them even more dangerous than other cancer cells. Identifying CSCs using natural products is a good option as it inhibits the recurrence of cancer with moderate various effects. Ursolic acid (UA) is a pentacyclic triterpenoid extracted from fruit and herbal remedies and has known anticancer functions against various cancer cells. However, its potential against CSCs remains uncertain. This study was planned to examine the induction of cell apoptosis by the UA. For cell signaling studies, we performed experiments, which are real-time qPCR and immunoblotting. Also, various cellular processes were analyzed using flow cytometry. The results raised a barrier to cell proliferation by the UA in NTERA-2 and NCCIT cells. Morphological studies also confirmed the UA's ability to cause cell death in embryonic CSCs. Examination of cell death importation showed that the UA formed the expression of the iNOS and thus the cell generation and mitochondrial reactive oxygen generation, which created a reaction to cellular DNA damage by raising the protein levels of phospho-histone ATR and ATM. In addition, the UA created the binding of the G0/G1 cell cycle to NTERA-2 and NCCIT cells, improved the expression levels of p21 and p27, and reduced the expression levels of CDK4, cyclin D1, and cyclin E, confirming the UA's ability to initiate cell cycle arrest. Finally, the UA created an internal mechanism of apoptosis in the embryonic CSC using BAX and cytochrome c regulation as well as the regulation of BCL-xL and BCL-2 proteins. Therefore, UA could be the best candidate for targeting CSCs and thus suppressing the emergence of cancer.

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/ß-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.

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/ß-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.

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.

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-1ß, 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.

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. Toll­like receptor 4 (TLR­4) is an inflammatory response receptor that activates JAK2 during inflammation. STAT3 is a transcription factor for the pro­inflammatory cytokine IL­6 in inflammation. Sulfur is an essential element in the amino acids and is required for growth and development. Non­toxic sulfur (NTS) can be used in livestock feeds as it lacks toxicity. The present study aimed to inhibit LPS­induced inflammation in C2C12 myoblasts using NTS by regulating TLR­4 and JAK2/STAT3 signaling via the modulation of IL­6. The 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium 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 enzyme­linked immunosorbent assays were used to determine the binding activity of proteins. The results indicated that NTS demonstrated a protective effect against LPS­induced cell death and inhibited LPS­induced expression of TLR­4, JAK2, STAT3 and IL­6. In addition, NTS inhibited the expression of nuclear phosphorylated­STAT3 and its binding to the IL­6 promoter. Therefore, NTS may be a potential candidate drug for the treatment of inflammation.

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.

Sulfur Compounds Inhibit High Glucose-Induced Inflammation by Regulating NF-κB Signaling in Human Monocytes.

High glucose-induced inflammation leads to atherosclerosis, which is considered a major cause of death in type 1 and type 2 diabetic patients. Nuclear factor-kappa B (NF-κB) plays a central role in high glucose-induced inflammation and is activated through toll-like receptors (TLRs) as well as canonical and protein kinase C-dependent (PKC) pathways. Non-toxic sulfur (NTS) and methylsulfonylmethane (MSM) are two sulfur-containing natural compounds that can induce anti-inflammation. Using Western blotting, real-time polymerase chain reaction, and flow cytometry, we found that high glucose-induced inflammation occurs through activation of TLRs. An effect of NTS and MSM on canonical and PKC-dependent NF-κB pathways was also demonstrated by western blotting. The effects of proinflammatory cytokines were investigated using a chromatin immunoprecipitation assay and enzyme-linked immunosorbent assay. Our results showed inhibition of the glucose-induced expression of TLR2 and TLR4 by NTS and MSM. These sulfur compounds also inhibited NF-κB activity through reactive oxygen species (ROS)-mediated canonical and PKC-dependent pathways. Finally, NTS and MSM inhibited the high glucose-induced expression of interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α and binding of NF-κB protein to the DNA of proinflammatory cytokines. Together, these results suggest that NTS and MSM may be potential drug candidates for anti-inflammation therapy.

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.

Non­toxic sulfur enhances growth hormone signaling through the JAK2/STAT5b/IGF­1 pathway in C2C12 cells.

Insulin­like growth factor­1 (IGF­1) regulates cell growth, glucose uptake and protein metabolism, and is required for growth hormone (GH) signaling­mediated insulin production and secretion. IGF1 expression is associated with STAT5, which binds to a region (TTCNNNGAA) of the gene. Although sulfur is used in various fields, the toxicity of this element is a significant disadvantage as it causes indigestion, vomiting, diarrhea, pain and migraine. Therefore, it is difficult to conduct in vitro experiments to directly determine the effects of dietary sulfur. Additionally, it is difficult to dissolve non­toxic sulfur (NTS). The present study aimed to identify the role of NTS in GH signaling as a Jak2/STAT5b/IGF­1 pathway regulator. MTT assay was used to identify an optimum NTS concentration for C2C12 mouse muscle cells. Western blotting, RT­PCR, chromatin immunoprecipitation, overexpression and small interfering RNA analyses were performed. NTS was dissolved in 1 mg/ml DMSO and could be used in vitro. Therefore, the present study determined whether NTS induced mouse muscle cell growth via GH signaling. NTS notably increased STAT5b binding to the Igf1 promoter. NTS also promoted GH signaling by upregulating GH receptor expression, similar to GH treatment. NTS enhanced GH signaling by regulating Jak2/STAT5b/IGF­1 signaling pathway factor expression in C2C12 mouse muscle cells. Thus, NTS may be used as a GH­enhancing growth stimulator.

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/ß-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/ß-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.