Garcinone E induces apoptosis and inhibits migration and invasion in ovarian cancer cells

Paraptosis: a non-classical paradigm of cell death for cancer therapy

Due to the sustained proliferative potential of cancer cells, inducing cell death is a potential strategy for cancer therapy. Paraptosis is a mode of cell death characterized by endoplasmic reticulum (ER) and/or mitochondrial swelling and cytoplasmic vacuolization, which is less investigated. Considerable evidence shows that paraptosis can be triggered by various chemical compounds, particularly in cancer cells, thus highlighting the potential application of this non-classical mode of cell death in cancer therapy. Despite these findings, there remain significant gaps in our understanding of the role of paraptosis in cancer. In this review, we summarize the current knowledge on chemical compound-induced paraptosis. The ER and mitochondria are the two major responding organelles in chemical compound-induced paraptosis, which can be triggered by the reduction of protein degradation, disruption of sulfhydryl homeostasis, overload of mitochondrial Ca2+, and increased generation of reactive oxygen species. We also discuss the stumbling blocks to the development of this field and the direction for further research. The rational use of paraptosis might help us develop a new paradigm for cancer therapy.

Structure and activity relationship analysis of xanthones from mangosteen: Identifying garcinone E as a potent dual EGFR and VEGFR2 inhibitor

BACKGROUND

Xanthones are among the most fundamental phytochemicals in nature. The anti-cancer activities of xanthones and their derivatives have been extensively studied. Recently, we found that garcinone E (GE), an effective anti-cancer phytochemical isolated from mangosteen (Garcinia mangostanal.), showed promising anti-cancer effects in vitro and in vivo. However, little is known about its effects on epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) activity.

PURPOSE

This study aimed to identify potent dual EGFR and VEGFR2 inhibitors from mangosteen-derived xanthones using structure-activity relationship analyses.

STUDY DESIGN

The interaction of xanthones with EGFR and VEGFR2 was analyzed using molecular docking experiments. The kinase activities of EGFR and VEGFR2 were determined using bioluminescence assays. The rat aortic ring and Matrigel plug angiogenesis assays were used to evaluate blood vessel formation ex vivo and in vivo. A breast tumor-bearing nude mouse model was established to examine the anti-tumor effects of different xanthones.

RESULTS

Molecular docking analysis showed that GE bound tightly to EGFR and VEGFR2, with binding energies of -9.73 and -9.56 kcal/mol, respectively. Kinase activity assessment showed that GE strongly inhibited both EGFR and VEGFR2 kinase activity, with IC50 values of 315.4 and 158.2 nM, respectively. Moreover, GE significantly abolished the EGF- and VEGF-induced phosphorylation of EGFR and VEGFR2, respectively. GE also showed strong inhibitory effects on cancer cell growth, endothelial cell migration, invasion, and tube formation. Ex vivo and in vivo angiogenesis assays showed that GE dose-dependently suppressed blood vessel formation in the rat aorta, Matrigel plugs, and transgenic zebrafish embryos, with the lowest effective concentration of 0.25 μM. Furthermore, GE (2 mg/kg) strongly inhibited tumor growth and reduced tumor weight in MDA-MB-231 breast tumor-xenografted mice. GE significantly reduced microvessel density and downregulated the expression of VEGFR2, EGFR, and Ki67 in tumor tissues.

CONCLUSION

The present study demonstrated that GE was the most potent dual inhibitor of EGFR and VEGFR2 among all xanthones tested. These findings may provide valuable information for the future development of novel and effective dual inhibitors of EGFR and VEGFR2.

Targeting endoplasmic reticulum stress signaling in ovarian cancer therapy

The endoplasmic reticulum (ER), an organelle present in various eukaryotic cells, is responsible for intracellular protein synthesis, post-translational modification, and folding and transport, as well as the regulation of lipid and steroid metabolism and Ca2+ homeostasis. Hypoxia, nutrient deficiency, and a low pH tumor microenvironment lead to the accumulation of misfolded or unfolded proteins in the ER, thus activating ER stress (ERS) and the unfolded protein response, and resulting in either restoration of cellular homeostasis or cell death. ERS plays a crucial role in cancer oncogenesis, progression, and response to therapies. This article reviews current studies relating ERS to ovarian cancer, the most lethal gynecologic malignancy among women globally, and discusses pharmacological agents and possible targets for therapeutic intervention.

Garcinone E suppresses breast cancer growth and metastasis by modulating tumor-associated macrophages polarization via STAT6 signaling

Cancer metastasis remains the most common cause of death in breast cancer patients. Tumor-associated macrophages (TAMs) are a novel therapeutic target for the treatment of metastatic breast cancer. Despite the good anti-cancer activity of garcinone E (GE), there are no reports on its therapeutic effects on breast cancer metastasis. The objective of this study was to examine the anti-cancer effects of GE on metastatic breast cancer. RAW 264.7 and THP-1 cells were polarized to M2 macrophages by IL-4/IL-13 in vitro. A 4T1 mouse breast cancer model and the tail vein breast cancer metastasis model were used to explore the effect of GE on breast cancer growth and metastasis in vivo. In vitro studies showed that GE dose-dependently suppressed IL-4 + IL-13-induced expression of CD206 in both RAW 264.7 cells and differentiated THP-1 macrophages. However, GE did not affect the LPS + IFN-γ-induced polarization to the M1-like macrophages in vitro. GE inhibited the expression of the M2 macrophage specific genes in RAW 264.7 cells, and simultaneously impaired M2 macrophage-induced breast cancer cell proliferation and migration, and angiogenesis. In animal studies, GE significantly suppressed tumor growth, angiogenesis, and lung metastasis in 4T1 tumor-bearing mice, without causing toxicity. In both tumor and lung tissues, the proportion of M2-like TAMs was significantly decreased while the proportion of M1-like TAMs was markedly increased by GE treatment. Mechanistically, GE inhibited phosphorylation of STAT6 in vitro and in vivo. Our results demonstrate for the first time that GE suppresses breast cancer growth and pulmonary metastasis by modulating M2-like macrophage polarization through the STAT6 signaling pathway.

Dual RNase activity of IRE1 as a target for anticancer therapies

The unfolded protein response (UPR) is a cellular mechanism that protects cells during stress conditions in which there is an accumulation of misfolded proteins in the endoplasmic reticulum (ER). UPR activates three signaling pathways that function to alleviate stress conditions and promote cellular homeostasis and cell survival. During unmitigated stress conditions, however, UPR activation signaling changes to promote cell death through apoptosis. Interestingly, cancer cells take advantage of this pathway to facilitate survival and avoid apoptosis even during prolonged cell stress conditions. Here, we discuss different signaling pathways associated with UPR and focus specifically on one of the ER signaling pathways activated during UPR, inositol-requiring enzyme 1α (IRE1). The rationale is that the IRE1 pathway is associated with cell fate decisions and recognized as a promising target for cancer therapeutics. Here we discuss IRE1 inhibitors and how they might prove to be an effective cancer therapeutic.

Garcinone E triggers apoptosis and cell cycle arrest in human colorectal cancer cells by mediating a reactive oxygen species–dependent JNK signaling pathway

Despite various therapeutic approaches, colorectal cancer is among the most fatal diseases globally. Hence, developing novel and more effective methods for colorectal cancer treatment is essential. Recently, reactive oxygen species (ROS)/JNK signaling pathway has been proposed as the potential target for the anticancer drug discovery. The present study investigated the anticancer effects of the bioactive xanthone garcinone E (GAR E) in mangosteen and explored its underlying mechanism of action. HT-29 and Caco-2 cancer cells were used as in vitro models to study the anticancer effect of GAR E. The findings demonstrated that GAR E inhibited colony formation and wound healing, whereas triggered the production of ROS, which induced mitochondrial dysfunction and apoptosis, causing cell cycle arrest at the Sub G1 phase. Additionally, GAR E treatment elevated the ratio of Bax/Bcl-2 and activated PARP, caspases 3 and 9, and JNK1/2. These GAR E-induced cytotoxic activities and expression of signaling proteins were reversed by the antioxidant N-acetyl-L-cysteine and JNK inhibitor SP600125, indicating the involvement of ROS/JNK signaling pathways. In vivo experiments using an HT-29 xenograft nude mouse model also demonstrated the antitumor effect of GAR E. In conclusion, our findings showed that GAR E might be potentially effective in treating colorectal cancer and provided insights into the development of xanthones as novel chemotherapeutic agents.

Mangosteen for malignancy prevention and intervention: Current evidence, molecular mechanisms, and future perspectives

Mangosteen (Garcinia mangostana L.), also known as the "queen of fruits", is a tropical fruit of the Clusiacea family. While native to Southeast Asian countries, such as Thailand, Indonesia, Malaysia, Myanmar, Sri Lanka, India, and the Philippines, the fruit has gained popularity in the United States due to its health-promoting attributes. In traditional medicine, mangosteen has been used to treat a variety of illnesses, ranging from dysentery to wound healing. Mangosteen has been shown to exhibit numerous biological and pharmacological activities, such as antioxidant, anti-inflammatory, antibacterial, antifungal, antimalarial, antidiabetic, and anticancer properties. Disease-preventative and therapeutic properties of mangosteen have been ascribed to secondary metabolites called xanthones, present in several parts of the tree, including the pericarp, fruit rind, peel, stem bark, root bark, and leaf. Of the 68 mangosteen xanthones identified so far, the most widely-studied are α-mangostin and γ-mangostin. Emerging studies have found that mangosteen constituents and phytochemicals exert encouraging antineoplastic effects against a myriad of human malignancies. While there are a growing number of individual research papers on the anticancer properties of mangosteen, a complete and critical evaluation of published experimental findings has not been accomplished. Accordingly, the objective of this work is to present an in-depth analysis of the cancer preventive and anticancer potential of mangosteen constituents, with a special emphasis on the associated cellular and molecular mechanisms. Moreover, the bioavailability, pharmacokinetics, and safety of mangosteen-derived agents together with current challenges and future research avenues are also discussed.

Comparative Dynamic Features of Apo and Bound MDM2 Protein Reveal the Mechanism of Inhibitor Recognition for Anti-Cancer Activity

BACKGROUND

Mouse Double Minute 2 Homolog (MDM2) oncogenic protein is the principal cellular antagonist of the p53 tumor suppressor gene. Restoration of p53 activity by inhibiting the MDM2-P53 interactions at the molecular level has become the cornerstone of cancer research due to its promising anticancer effects. Natural medicinal products possess various chemical structures and represent an essential source for drug discovery. α-Mangostin (AM) and gambogic acid (G250) are plant-derived compounds that showed inhibitory effects on MDM2-P53 interactions in vitro and in vivo.

METHODS

Despite the many clinical studies which performed deeper insight about the molecular understanding of the structural mechanisms exhibited by α-Mangostin and Gambogic acid-binding to MDM2 remains critical. In this study, comparative molecular dynamics simulations were performed for each Apo and bound p53 and MDM2 proteins to shed light on the MDM2-p53 interactions and get a better understanding of the inhibition mechanisms.

RESULTS

Results revealed atomistic interaction of AM and G250 within the MDM2-p53 interaction cleft. Both compounds mediate the interaction between the α-helix motifs of the p53 amino-terminal domain, which caused a significant separation between orthogonally opposed residues, specifically Lys8 and Gly47 residues of the p53 and MDM2, respectively. Contrasting changes in magnitudes were observed in per-residue fluctuation on AM and G250 (~0.04 nm and ~2.3 nm, respectively). The Radius of gyration (~0.03 nm and 0.04 nm, respectively), C-alpha deviations (~0.06 nm and 0.1 nm, respectively). The phenolic group of AM was found to establish hydrogen interactions with Glu28 and His96 residues of MDM2. The trioxahexacyclo-ring of G250 also forms hydrogen bond interactions with Lys51 and Leu26 residues of MDM2.

CONCLUSION

Utilizing the information provided on the inhibitory binding mode adopted by each compound in this study may further assist in the tailored designs for cancer therapeutics.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

Natural Prenylated Xanthones as Potential Inhibitors of PI3k/Akt/mTOR Pathway in Triple Negative Breast Cancer Cells

Three prenylated xanthones, garcinone E (1: ), bannaxanthone D (2: ) and bannanxanthone E (3: ) were isolated from the leaves of Garcinia mckeaniana Graib. Their structures were elucidated by spectral methods and compared with literature data. To evaluate their anti-proliferative effects in tumor cells, firstly, cisplatin was used as a positive control and the effects of compound 1:  - 3: were determined by performing MTT assay in MDA-MB-231, CNE-2 and A549 cancer cells. The results showed compound 1:  - 3: exhibited stronger inhibitory effect than cisplatin in MDA-MB-231. Further effects of compound 1:  - 3: in TNBC MDA-MB-231 and MDA-MB-468 cells were examined by performing cell cycle and apoptosis assays. The results indicated that compound 1:  - 3: had ability to arrest cell cycle at G2/M phase and induce apoptosis. Furthermore, compound 2: significantly down-regulated PI3K, Akt and mTOR levels in both total proteins and phosphorylated form, which is its potential anti-cancer mechanism. These findings indicated that those prenylated xanthones might serve as promising leading compounds for the development of anticancer drug for TNBC.

ERp44 Regulates the Proliferation, Migration, Invasion, and Apoptosis of Gastric Cancer Cells Via Activation of ER Stress

Gastric cancer (GC) is one of the most prevalent malignancies worldwide. Endoplasmic reticulum (ER) stress plays a key role in the progression of GC. Rapid proliferation of tumor cells interferes with ER homeostasis, leading to ER stress and triggering unfolded protein response. Therefore, it is very necessary to investigate abnormally expressed ER resident proteins (ERp) in cancer cells. This study aimed to investigate the possible roles of ERp44. The mRNA and protein expression of genes were detected using qRT-PCR and western blot. Cell apoptosis was calculated using flow cytometry. Cell proliferation was determined using CCK-8 and colony formation assay. Cell migration was detected by wound healing, and cell invasion was measured by transwell assay. We found that ERp44 was obviously decreased in GC tissues. Furthermore, ERp44 overexpression distinctly suppressed the proliferation, migration, and invasion of MGC-803 and KATO III cells. In contrast, apoptosis was promoted by ERp44 overexpression. Furthermore, mechanistic studies revealed that overexpression of ERp44 inhibited malignant biological processes by regulating the eIF-2α/CHOP signaling pathway. Taken together, our data demonstrated that ERp44 regulated the proliferation, migration, invasion, and apoptosis via ERp44/eIF-2α/CHOP axis in GC. Targeting the ERp44and ER stress may be a promising strategy for GC.

TIMP2 mediates endoplasmic reticulum stress contributing to sepsis-induced acute kidney injury

Tissue inhibitor of metalloproteinase 2 (TIMP2) has been recognized as an important biomarker for predicting acute kidney injury (AKI) because of its involvement in the process of inflammation and apoptosis in septic AKI. Endoplasmic reticulum (ER) stress, a condition of disrupted ER homeostasis, is implicated in multiple pathophysiological processes, including kidney disease. Herein, we investigated the correlation between ER stress and septic AKI and further explored how TIMP2 regulated ER stress-mediated apoptosis. To assess the role of TIMP2 in sepsis-induced AKI, we used a cecal ligation and puncture (CLP) model in mice with tubule-specific deficiency of TIMP2 (Ksp-Cre/TIMP2^{flox / flox} ) and their wild-type counterparts. Compared to the wild-type mice, TIMP2-deficient mice demonstrated lower serum creatinine levels and decreased ER stress-mediated apoptosis when subjected to CLP. Interestingly, in human kidney (HK-2) cells, overexpression of TIMP2 caused ER stress, whereas TIMP2 knockdown attenuated lipopolysaccharide-induced ER stress and apoptosis. TIMP2 interacted with the binding immunoglobulin protein, an ER chaperone, and facilitates its extracellular secretion, thereby triggering ER stress. This study identified that the deletion of TIMP2 in mouse tubules mitigated sepsis-induced AKI by inhibiting ER stress-mediated apoptosis, which might be a potential therapeutic strategy to alleviate renal injury.

The purple mangosteen (Garcinia mangostana): Defining the anticancer potential of selected xanthones

The purple mangosteen (Garcinia mangostana) is a popular Southeast Asian fruit that has been used traditionally for its health promoting benefits for years. Unique to the mangosteen are a class of phytochemicals known as xanthones that have been reported to display significant anti-cancer and anti-tumor activities, specifically through the promotion of apoptosis, targeting of specific cancer-related proteins, or modulation of cell signaling pathways. α-Mangostin, the most abundant xanthone isolated from the mangosteen, has received substantial attention as it has proven to be a potent phytochemical, specifically as an anticancer agent, in numerous different cancer cell studies and cancer animal models. While the mechanisms for these anticancer effects have been reported in many studies, lesser xanthones, including gartanin, β-mangostin, γ-mangostin, garcinone C, and garcinone E, and mangosteen extracts from the pericarp, roots, rind, and stem show promise for their anticancer activity but their mechanisms of action are not as well developed and remain to be determined. Mangosteen products appear safe and have been well tolerated in human clinical trials where they show antioxidant activity, though their clinical anticancer activity has not yet been evaluated. This review summarizes the work that has been done to explore and explain the anticancer and antitumor activities of α-mangostin, lesser xanthones, and mangosteen extracts in vitro, in vivo, and in humans in various cancers.

Functional analysis of N-acetylglucosaminyltransferase-I knockdown in 2D and 3D neuroblastoma cell cultures

Tumor development can be promoted/suppressed by certain N-glycans attached to proteins at the cell surface. Here we examined aberrant neuronal properties in 2D and 3D rat neuroblastoma (NB) cell cultures with different N-glycan populations. Lectin binding studies revealed that the engineered N-glycosylation mutant cell line, NB_1(-Mgat1), expressed solely oligomannose N-glycans, and verified that the parental cell line, NB_1, and a previous engineered N-glycosylation mutant, NB_1(-Mgat2), expressed significant levels of higher order N-glycans, complex and hybrid N-glycans, respectively. NB_1 grew faster than mutant cell lines in monolayer and spheroid cell cultures. A 2-fold difference in growth between NB_1 and mutants occurred much sooner in 2D cultures relative to that observed in 3D cultures. Neurites and spheroid cell sizes were reduced in mutant NB cells of 2D and 3D cultures, respectively. Cell invasiveness was highest in 2D cultures of NB_1 cells compared to that of NB_1(-Mgat1). In contrast, NB_1 spheroid cells were much less invasive relative to NB_1(-Mgat1) spheroid cells while they were more invasive than NB_1(-Mgat2). Gelatinase activities supported the ranking of cell invasiveness in various cell lines. Both palladin and HK2 were more abundant in 3D than 2D cultures. Levels of palladin, vimentin and EGFR were modified in a different manner under 2D and 3D cultures. Thus, our results support variations in the N-glycosylation pathway and in cell culturing to more resemble in vivo tumor environments can impact the aberrant cellular properties, particularly cell invasiveness, of NB.

Novel α-Mangostin Derivatives from Mangosteen (Garcinia mangostana L.) Peel Extract with Antioxidant and Anticancer Potential

The mangosteen peels contain biologically active compounds, with antioxidant and anticancer properties. Among these isolated phytochemicals, α-mangostin is one of the most powerful natural antioxidants and anticancer compounds. This study focused on synthesizing novel α-mangostin (α-MG) derivatives at positions of C-3 and C-6 from extracted α-MG of mangosteen peels and investigating antioxidant and anticancer activities. The structures of the synthesized compounds were determined by using MS, 1H-NMR, 13C-NMR, and HPLC. The analysis of the interaction between structure and bioactivity showed that phenol groups on C-3 and C-6 positions play a crucial role in antiproliferative activity to boost both anticancer efficacy and drug-like properties. The antioxidant activity of α-MG and its derivatives were investigated by the DPPH method. Among α-MG derivatives, 1-hydroxy-7-methoxy-2,8-bis(3-methylbut-2-en-1-yl)-9-oxo-9H-xanthene-3,6-diyl bis(2-bromobenzoate) (compound 4) exhibited significant antioxidant property. The in vitro cytotoxicity against various cancer cell lines (HeLa, MCF-7, NCI–H460, and HepG2) was evaluated by the standard sulforhodamine B assay. The anticancer activities (HeLa, MCF-7, NCI–H460, and HepG2) of compound 4 are five to six times higher than those of α-MG and other derivatives. The acetylation at C-3 and C-6 of α-MG by halogen of benzoyl greatly improved cancer cell toxicity. Our results provide new opportunities for further explorations of α-MG derivatives for antioxidant property and promise as drugs in cancer therapy.

Marchantia polymorpha L. ethanol extract induces apoptosis in hepatocellular carcinoma cells via intrinsic- and endoplasmic reticulum stress-associated pathways

Background

Marchantia polymorpha L. is a kind of Chinese herbal medicine and has various biological activities including antioxidant and antifungal. However, it is not clear about the antitumor effect and mechanism of M. polymorpha. We prepared M. polymorpha ethanol extract (MPEE) and investigated its antitumor effect on hepatocellular carcinoma cells both in vitro and in vivo.

Methods

The viability of hepatocellular carcinoma cells was detected by MTT assay. The distribution of cell cycle was analyzed by propidium iodide (PI) staining. The morphology of nuclei was observed by Hoechst 33258 staining. Apoptosis was detected by Annexin V/PI staining. JC-1 fluorescent probe and DCFH-DA were used to detect the mitochondrial membrane potential (ΔψM) and the level of reactive oxygen species (ROS), respectively. Caspase inhibitors were used to test the function of caspase in the induction of apoptosis. Quantitative real time polymerase chain reaction (qRT-PCR) and Western blot were used to evaluate the levels of mRNA and protein, respectively. Differentially expressed genes and signaling pathways were identified by transcriptome analysis. The H22 tumor mouse model was used to detect the antitumor effect of the extract.

Results

MPEE significantly suppressed the migration and growth of BEL-7404, HepG2 and H22 cells in a dose- and time-dependent manner through induction of apoptosis characterized by chromosomal condensation and cell cycle arrest at G0/G1 and G2/M phases. MPEE induced mitochondria-dependent apoptosis via upregulation of Bax and downregulation of Bcl-2 to reduce mitochondrial membrane potential and increase the release of cytochrome c. The levels of cleaved caspase-8 and -9 were significantly increased, which sequentially activated caspase-3 to cleave PARP. We further found that MPEE significantly increased ROS production and activated endoplasmic reticulum (ER) stress associated-apoptotic signaling pathway. Moreover, MPEE significantly inhibited H22 tumor growth in mouse model and improved the survival of tumor mice.

Conclusion

These results suggested that MPEE suppressed hepatocellular carcinoma cell growth through induction of apoptosis via intrinsic- and ER stress-associated pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00504-4.

Covalent immobilization of DJK-5 peptide on porous titanium for enhanced antibacterial effects and restrained inflammatory osteoclastogenesis

Currently, implant-related bone infection characterized by aggravated infection-induced inflammatory responses and osteolysis, remains a severe challenge in orthopedic surgery, especially in patients with osteoporosis. Attempts to control such responses using biomaterials with combined immunomodulatory and anti-bacterial properties may provide novel strategies. Herein, DJK-5, a class of host defense peptides (HDPs) with established antimicrobial and immunomodulatory functions, was introduced into porous Ti alloy. Our results indicated that the DJK-5 immobilized surfaces showed intrinsically multifunctional properties, including antibacterial ability, anti-inflammation, biocompatibility and osteolysis-inhibiting properties. The results demonstrated that the antibacterial efficiency of DJK-5 functionalized surfaces was over 90 % for both Gram-positive and Gram-negative bacteria. Specifically, DJK-5 functionalized samples also possessed the excellent anti-bacterial activity against a mixture of bacterial strains, including S. aureus, S. epidermidis and P. aeruginosa, with an antibacterial rate against mixed bacteria reaching 91.36 %, as well as reduced biofilm formation. The remarkable anti-bacterial efficacy was likely based on the direct anti-bacterial effect of DJK-5, which destroyed the integrity of bacteria membranes, leading to the leakage of intracellular materials. Additionally, the immobilized DJK-5 surfaces could indirectly kill bacteria through promoted macrophage capacity to bacteria uptake. Furthermore, DJK-5 functionalized surfaces suppressed inflammatory reaction by decreasing the release of pro-inflammatory factors and increasing the secretions of anti-inflammatory factors, and thereby impeded the activation of NF-κB signal pathway, which resulted in the disruption of the actin rings and decreased Tracp5b expressions. Based on these promising findings, the multi-functional DJK-5 immobilized titanium represents an efficient alternative to realize better osseointegration in sever implant-associated bacterial infections.

TGFβ2-mediated epithelial-mesenchymal transition and NF-κB pathway activation contribute to osimertinib resistance

Osimertinib (AZD9291) has been widely used for the treatment of EGFR mutant non-small cell lung cancer. However, resistance to osimertinib is inevitable. In this study we elucidated the molecular mechanisms of resistance in osimertinib-resistant NCI-H1975/OSIR cells. We showed that NCI-H1975/OSIR cells underwent epithelial-mesenchymal transition (EMT), which conferred sensitivity to the GPX4 inhibitor 1S, 3R-RSL3 to induce ferroptotic cell death. The EMT occurrence resulted from osimertinib-induced upregulation of TGFβ2 that activated SMAD2. On the other hand, we revealed that NCI-H1975/OSIR cells were highly dependent on NF-κB pathway for survival, since treatment with the NF-κB pathway inhibitor BAY 11-7082 or genetic silence of p65 caused much greater cell death as compared with the parental NCI-H1975 cells. In NCI-H1975 cells, osimertinib activated NF-κB pathway, evidenced by the increased p65 nuclear translocation, which was abolished by knockdown of TGFβ2. In the cancer genome atlas lung adenocarcinoma data, TGFB2 transcript abundance significantly correlated with EMT-associated genes and NF-κB pathway. In addition, coexistence of EMT and activation of NF-κB pathway was observed in several NCI-H1975/OSIR clones. These findings shed new light on distinct roles of TGFβ2 in osimertinib-resistant cells and provide new strategies for treatment of this resistant status.

Identification and Pharmacokinetics of Quinone Reductase 2 Inhibitors after Oral Administration of Garcinia mangostana L. Extract in Rat by LC-MS/MS

Garcinia mangostana L. (mangosteen) is a famous tropical fruit that contains a large number of xanthones. Regular consumption of mangosteen may confer health benefits and prevent some diseases, such as malaria. Quinone reductase 2 (QR-2) is a cytosolic enzyme found in human red blood cells, and it is becoming a target for chemoprevention because it is involved in the mechanisms of several diseases, including malaria. To understand whether the xanthones present in mangosteen might inhibit the activity of QR-2, blood samples were collected from rat following the oral administration of mangosteen extract and then incubated with QR-2 followed by UF-HPLC-QTOF/MS analysis to rapidly screen for and identify the QR-2-inhibiting xanthones. A total of 16 xanthones were identified, and six of these (α-mangostin, γ-mangostin, 8-deoxyartanin, 1,3,7-trihydroxy-2,8-di(3-methylbut-2-enyl)xanthone, garcinone E, and 9-hydroxycalabaxanthone) were subjected to QR-2 inhibition assay. γ-Mangostin exhibited the strongest inhibition, achieving an IC₅₀ value of 3.82 ± 0.51 μM. Its interaction with QR-2 was found to involve hydrogen bond and arene-arene interaction as revealed by molecular docking. The present study could provide new insight into the potential application of mangosteen as functional food ingredients for inhibiting the activity of QR-2. However, the extent of daily intake of mangosteen required and the exact contribution of mangosteen to the prevention and treatment of malaria remain subjects of further study.

Knockdown of N-Acetylglucosaminyltransferase-II Reduces Matrix Metalloproteinase 2 Activity and Suppresses Tumorigenicity in Neuroblastoma Cell Line

Neuroblastoma (NB) development and progression are accompanied by changes in N-glycans attached to proteins. Here, we investigated the role of N-acetylglucosaminyltransferase-II (GnTII, MGAT2) protein substrates in neuroblastoma (NB) cells. MGAT2 was silenced in human BE(2)-C NB (HuNB) cells to generate a novel cell line, HuNB(-MGAT2), lacking complex type N-glycans, as in rat B35 NB cells. Changes in N-glycan types were confirmed by lectin binding assays in both cell lines, and the rescued cell line, HuNB(-/+MGAT2). Western blotting of cells heterologously expressing a voltage-gated K+ channel (Kv3.1b) showed that some hybrid N-glycans of Kv3.1b could be processed to complex type in HuNB(-/+MGAT2) cells. In comparing HuNB and HuNB(-MGAT2) cells, decreased complex N-glycans reduced anchorage-independent cell growth, cell proliferation, and cell invasiveness, while they enhanced cell-cell interactions. Cell proliferation, invasiveness and adhesion of the HuNB(-/+MGAT2) cells were more like the HuNB than HuNB(-MGAT2). Western blotting revealed lower protein levels of MMP-2, EGFR and Gab2 in glycosylation mutant cells relative to parental cells. Gelatin zymography demonstrated that decreased MMP-2 protein activity was related to lowered MMP-2 protein levels. Thus, our results support that decreased complex type N-glycans suppress cell proliferation and cell invasiveness in both NB cell lines via remodeling ECM.

DNA damage response and repair in ovarian cancer: Potential targets for therapeutic strategies

Ovarian cancer is among the most lethal gynecologic malignancies with a poor survival prognosis. The current therapeutic strategies involve surgery and chemotherapy. Research is now focused on novel agents especially those targeting DNA damage response (DDR) pathways. Understanding the DDR process in ovarian cancer necessitates having a detailed knowledge on a series of signaling mediators at the cellular and molecular levels. The complexity of the DDR process in ovarian cancer and how this process works in metastatic conditions is comprehensively reviewed. For evaluating the efficacy of therapeutic agents targeting DNA damage in ovarian cancer, we will discuss the components of this system including DDR sensors, DDR transducers, DDR mediators, and DDR effectors. The constituent pathways include DNA repair machinery, cell cycle checkpoints, and apoptotic pathways. We also will assess the potential of active mediators involved in the DDR process such as therapeutic and prognostic candidates that may facilitate future studies.

Role of Endoplasmic Reticulum Stress in the Anticancer Activity of Natural Compounds

Cancer represents a serious global health problem, and its incidence and mortality are rapidly growing worldwide. One of the main causes of the failure of an anticancer treatment is the development of drug resistance by cancer cells. Therefore, it is necessary to develop new drugs characterized by better pharmacological and toxicological profiles. Natural compounds can represent an optimal collection of bioactive molecules. Many natural compounds have been proven to possess anticancer effects in different types of tumors, but often the molecular mechanisms associated with their cytotoxicity are not completely understood. The endoplasmic reticulum (ER) is an organelle involved in multiple cellular processes. Alteration of ER homeostasis and its appropriate functioning originates a cascade of signaling events known as ER stress response or unfolded protein response (UPR). The UPR pathways involve three different sensors (protein kinase RNA(PKR)-like ER kinase (PERK), inositol requiring enzyme1α (IRE1) and activating transcription factor 6 (ATF6)) residing on the ER membranes. Although the main purpose of UPR is to restore this organelle's homeostasis, a persistent UPR can trigger cell death pathways such as apoptosis. There is a growing body of evidence showing that ER stress may play a role in the cytotoxicity of many natural compounds. In this review we present an overview of different plant-derived natural compounds, such as curcumin, resveratrol, green tea polyphenols, tocotrienols, and garcinia derivates, that exert their anticancer activity via ER stress modulation in different human cancers.

Recent updates on metabolite composition and medicinal benefits of mangosteen plant

BACKGROUND

Mangosteen (Garcinia mangostana L.) fruit has a unique sweet-sour taste and is rich in beneficial compounds such as xanthones. Mangosteen originally been used in various folk medicines to treat diarrhea, wounds, and fever. More recently, it had been used as a major component in health supplement products for weight loss and for promoting general health. This is perhaps due to its known medicinal benefits, including as anti-oxidant and anti-inflammation. Interestingly, publications related to mangosteen have surged in recent years, suggesting its popularity and usefulness in research laboratories. However, there are still no updated reviews (up to 2018) in this booming research area, particularly on its metabolite composition and medicinal benefits.

METHOD

In this review, we have covered recent articles within the years of 2016 to 2018 which focus on several aspects including the latest findings on the compound composition of mangosteen fruit as well as its medicinal usages.

RESULT

Mangosteen has been vastly used in medicinal areas including in anti-cancer, anti-microbial, and anti-diabetes treatments. Furthermore, we have also described the benefits of mangosteen extract in protecting various human organs such as liver, skin, joint, eye, neuron, bowel, and cardiovascular tissues against disorders and diseases.

CONCLUSION

All in all, this review describes the numerous manipulations of mangosteen extracted compounds in medicinal areas and highlights the current trend of its research. This will be important for future directed research and may allow researchers to tackle the next big challenge in mangosteen study: drug development and human applications.

Antimetastatic Potential of Garcinone E in Human Oral Cancer Cells

Objective:

Oral cancer presents as a devastating type of malignancy. It is predominant in populations with high use of alcohol and various forms of tobacco as well as poor diets with low intake of fruits and vegetables. The present study focused on the potential of Garcinone E to inhibit HSC-4 oral cancer cell proliferation, migration and invasion.

Methods:

MTT and colony forming assays were performed to study antiproliferative effects of Garcinone E. Hoechst staining was used to determine levels of apoptosis, with cell invasion and scratch assays conducted for migration and invasion characteristics. The levels of MMPs and cytokines were quantified in Garcinone E treated cells by ELISA.

Results:

Garcinone E inhibited the proliferation and colony forming potential of HSC-4 cells. It also suppressed migration and invasion with inhibition of MMP-2 and MMP-9 expression. Moreover, it elevated IL-2 and reduced IL-6 expression in HSC-4 cells.

Conclusion:

Our results demonstrate for the first time that Garcinone E might inhibit metastasis of an oral cancer cell line by blocking invasion, migration and MMP production.

Induction of Apoptosis by Extract of Persian Gulf Marine Mollusk, Turbo Coronatus through the ROS-Mediated Mitochondrial Targeting on Human Epithelial Ovarian Cancer Cells

Despite recent improvements in treatment, ovarian cancer is still the leading cause of death from gynaecological malignancies. Today, marine mollusks are considered as natural source of new biologically and pharmacologically active compounds by scientists and the pharmaceutical industries. The aim of this study is to investigate the selective apoptotic effects of Turbo coronatus crude extract fractions on human epithelial ovarian cancer (EOC) cells and mitochondria. The cells and mitochondria were isolated from cancerous and non-cancerous ovarian tissues and exposed to IC₅₀ concentration of F1 fraction for evaluation of mitochondrial and cellular parameters. Our results showed that F1 fraction of T. coronatus crude extract significantly induced toxic effects only in the cancerous ovarian mitochondria, including increased reactive oxygen species (ROS) formation, mitochondrial membrane depolarization, mitochondrial swelling, and cytochrome c release.Flow-cytometry analysis demonstrated that F1 fraction of T. coronatus progressively induced apoptosis and necrosis only on EOC but not non-cancerous cells. We eventuallyconcluded that F1 fraction of T. coronatus crude extract selectively induces apoptosis in EOC through a ROS- mediated pathway.

γ-Mangostin alleviates liver fibrosis through Sirtuin 3-superoxide-high mobility group box 1 signaling axis

The activation of hepatic stellate cells (HSCs) plays a critical role in liver fibrosis. In the current study, γ-mangostin (γ-man), one of the major xanthones from mangosteen (Garcinia mangostana), was found to alleviate fibrogenesis in human immortalized HSCs (LX-2 cells) and in liver from chronic carbon tetrachloride (CCl₄) injured mice. γ-Man suppressed the expression levels of collagen I and α-smooth muscle actin (α-SMA) in LX-2 cells in both dose and time dependent manners. Furthermore, γ-man inhibited NAD(P)H oxidase activity through induction of sirtuin 3 (SIRT3), resulting in reduced intracellular oxidative stress in LX-2 cells. Moreover, γ-man stimulated the expression of histone deacetylase 1, which in turn decreased the acetylation and cytoplasmic shuttling of high mobility group box 1 (HMGB1), to impair autocrine HMGB1-induced HSC activation. In CCl₄-injured mice, γ-man enhanced the expression of SIRT3 and decreased the expression of HMGB1, resulting in decreased accumulation of collagen I and α-SMA in liver. Consequently, γ-man might be a potent candidate to treat oxidative stress induced liver fibrosis.

Salubrinal Enhances Doxorubicin Sensitivity in Human Cholangiocarcinoma Cells Through Promoting DNA Damage

Cholangiocarcinoma (CCA) is a highly malignant and aggressive tumor of the bile duct that arises from epithelial cells. Chemotherapy is an important treatment strategy for CCA patients, but its efficacy remains limited due to drug resistance. Salubrinal, an inhibitor of eukaryotic translation initiation factor 2 alpha (eIF2α), has been reported to affect antitumor activities in cancer chemotherapy. In this study, the authors investigated the effect of salubrinal on the chemosensitivity of doxorubicin in CCA cells. They showed that doxorubicin induces CCA cell death in a dose- and time-dependent manner. Doxorubicin triggers reactive oxygen species (ROS) generation and induces DNA damage in CCA cells. In addition, ROS inhibitor N-acetylcysteine (NAC) pretreatment inhibits doxorubicin-induced CCA cell death. Importantly, these data demonstrate a synergistic death induction effect contributed by the combination of salubrinal and doxorubicin in CCA cells. It is notable that salubrinal promotes doxorubicin-induced ROS production and DNA damage in CCA cells. Taken together, these data suggest that salubrinal enhances the sensitivity of doxorubicin in CCA cells through promoting ROS-mediated DNA damage.

New podolactones from the seeds of Podocarpus nagi and their anti-inflammatory effect

Podolactones are a class of structural diverse diterpenoid lactones, mainly isolated from the Podocarpus species. Several bioactivities have been disclosed for podolactones, including cytotoxicity and anti-atherosclerosis. In this study, the seeds of P. nagi were isolated by comprehensive chromatographic methods to obtain three new podolatones, named nagilactone B 1-O-β-D-glucoside (1), nagilactone N3 3-O-β-D-glucoside (2), and 2-epinagilactone B (3), as well as a known compound, nagilactone B (4). Their structures were determined by analyses of NMR and HRESIMS data. Compounds 1 and 2 significantly inhibited nitric oxide (NO) production on LPS-stimulated RAW264.7 macrophages, with IC₅₀ values of 0.18 ± 0.04 and 0.53 ± 0.03 μM, respectively. Indomethacin (IC₅₀ 4.21 ± 0.32 μM) was used as a positive control. Compound 1 suppressed the expression of inducible NO synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents.

Inhibitory effects of garcinone E on fatty acid synthase

Fatty acid synthase (FAS) is highly expressed in human adipocytes and cancer cells and is considered as a dual therapeutic target for obesity and cancer treatment. Garcinone E is a natural xanthone and exists in the pericarp of Garcinia mangostana. In previous studies, xanthones were reported to be highly active inhibitors of FAS. In the present study, the detailed inhibitory mechanism of garcinone E on FAS was investigated. We found that garcinone E inhibited the activity of FAS in a concentration-dependent manner with a half-inhibitory concentration value of 3.3 μM. The inhibition kinetic results showed that the inhibition of FAS by garcinone E was competitive with respect to acetyl-CoA, mixed competitive and noncompetitive with respect to malonyl-CoA, and noncompetitive to NADPH. In addition, garcinone E showed irreversible inhibition on FAS, which was different from all other xanthones. Since FAS is believed to be a therapeutic target for obesity and cancer treatment, these findings suggest the clinical potential of garcinone E in the prevention and treatment of both obesity and cancer.

Garcinone E exhibits both fast-binding reversible and time-dependent irreversible inhibition on the activity of fatty acid synthase.