Oleanane triterpenoid CDDO-Me inhibits growth and induces apoptosis in prostate cancer cells through a ROS-dependent mechanism

Triterpenoids from the roots of Sanguisorba officinalis and their Nrf2 stimulation activity

Thirteen undescribed ursane-type triterpenoids, named as sangosides A-M (1-13), including two nor-ursanes, one split ring-ursane and ten ursanes, along with thirty-six known triterpenoids (14-49) were isolated and identified from the roots of Sanguisorba officinalis (Rosaceae). Their structures and absolute configurations were elucidated through spectroscopic data, single-crystal X-ray crystallography and electronic circular dichroism analysis. Their Nrf2 activation activity was evaluated in 293 T cells in vitro. Compounds 2, 5-7, 9-13, 19, 25, 26, 28-39, 41 and 46 showed significant Nrf2 agonistic effects compared with the control group at 25 μM, their cytotoxicity and dose-effect relationship were further studied in a dose-dependent manner. Their structure-activity relationships analysis suggested that the pentacyclic triterpenoids (10, 11, 30-34 and 41) contains two pairs of double bonds on the C & E rings and the ursane-type triterpenoids (25 and 26) with a carbonyl to C-2 and a hydroxyl group at C-3 all showed a considerably Nrf2 activation activity. These results suggested that S. officinalis was worthy of further investigation to find small molecule Nrf2 activators and facilitate their utilization as natural antioxidants.

The Molecular Mechanisms of Oleanane Aldehyde-β-enone Cytotoxicity against Doxorubicin-Resistant Cancer Cells

Oleanane aldehyde-β-enone (OA), being the semi-synthetic derivative of the triterpenoid betulin, effectively inhibits the proliferation of HBL-100 and K562 cancer cells (IC50 0.47–0.53 µM), as well as the proliferation of their resistant subclones with high P-gp expression HBL-100/Dox, K562/i-S9 and K562/i-S9_Dox (IC50 0.45−1.24 µM). A molecular docking study, rhodamine efflux test, synergistic test with Dox, and ABC transporter gene expression were used to investigate the ability of OA to act as a P-gp substrate or inhibitor against Dox-resistant cells. We noted a trend toward a decrease in ABCB1, ABCC1 and ABCG2 expression in HBL-100 cells treated with OA. The in silico and in vitro methods suggested that OA is neither a direct inhibitor nor a competitive substrate of P-gp in overexpressing P-gp cancer cells. Thus, OA is able to overcome cellular resistance and can accumulate in Dox-resistant cells to realize toxic effects. The set of experiments suggested that OA toxic action can be attributed to activating intrinsic/extrinsic or only intrinsic apoptosis pathways in Dox-sensitive and Dox-resistant cancer cells, respectively. The cytotoxicity of OA in resistant cells is likely mediated by a mitochondrial cell death pathway, as demonstrated by positive staining with Annexin V–FITC, an increasing number of cells in the subG0/G1 phase, reactive oxygen species generation, mitochondrial dysfunction, cytochrome c migration and caspases-9,-6 activation.

Synthetic oleanane triterpenoid derivative CDDO-Me disrupts cellular bioenergetics to suppress pancreatic ductal adenocarcinoma via targeting SLC1A5

To investigate the potential antitumor activity of synthetic triterpenoid, methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) in pancreatic ductal adenocarcinoma (PDAC), MTT cytotoxicity assay, and xenograft nude mice assay were performed to evaluate tumor growth in vitro and in vivo. Seahorse XFe96 bioenergetics analyzer was applied to determine aerobic glycolysis and mitochondrial respiration. Western blot and quantitative reverse transcription-polymerase chain reactions are used to detect protein and messenger RNA transcripts of SLC1A5 and metabolic enzymes. We confirmed the strong antitumor activity of CDDO-Me in suppressing PDAC growth. Mechanistically, we demonstrated CDDO-Me induced mitochondrial respiration and aerobic glycolysis dysfunction. We also verified CDDO-Me downregulated glutamine transporter SLC1A5, resulting in excessive reactive oxygen species (ROS) levels that suppressed tumor growth. Moreover, we confirmed that SLC1A5 depletion reduced the ratio of glutathione/oxidized glutathione. We also found CDDO-Me could inhibit N-linked glycosylation of SLC1A5, which promotes protease-mediated degradation. Finally, we confirmed SLC1A5 was significantly overexpressed in PDAC and closely correlated with the poor prognosis of PDAC patients. Our work uncovers CDDO-Me is effective at suppressing PDAC cell growth in vitro and in vivo and illuminates CDDO-Me caused excessive ROS and cellular bioenergetics disruption which contributed to CDDO-Me inhibited PDAC growth. Our data highlights CDDO-Me could be considered a potential compound for PDAC therapy, and SLC1A5 could be a novel biomarker for PDAC patients.

Targeting Akt/NF-κB/p53 Pathway and Apoptosis Inducing Potential of 1,2-Benzenedicarboxylic Acid, Bis (2-Methyl Propyl) Ester Isolated from Onosma bracteata Wall. against Human Osteosarcoma (MG-63) Cells

Onosma bracteata Wall. is an important medicinal and immunity-enhancing herbs. This plant is commonly used in the preparation of traditional Ayurvedic drugs to treat numerous diseases. Inspired by the medicinal properties of this plant, the present study aimed to investigate the antiproliferative potential and the primary molecular mechanisms of the apoptotic induction against human osteosarcoma (MG-63) cells. Among all the fractions isolated from O. bracteata, ethyl acetate fraction (Obea) showed good antioxidant activity in superoxide radical scavenging assay and lipid peroxidation assay with an EC50 value of 95.12 and 80.67 µg/mL, respectively. Silica gel column chromatography of ethyl acetate (Obea) fraction of O. bracteata yielded a pure compound, which was characterized by NMR, FTIR, and HR-MS analysis and was identified as 1,2-benzene dicarboxylic acid, bis (2-methyl propyl) ester (BDCe fraction). BDCe fraction was evaluated for the antiproliferative potential against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung carcinoma A549 cell lines by MTT assay and exhibited GI50 values of 37.53 μM, 56.05 μM, and 47.12 μM, respectively. In Mg-63 cells, the BDCe fraction increased the level of ROS and simultaneously decreased the mitochondria membrane potential (MMP) potential by arresting cells at the G0/G1 phase, suggesting the initiation of apoptosis. Western blotting analysis revealed the upregulation of p53, caspase3, and caspase9 while the expressions of p-NF-κB, p-Akt and Bcl-xl were decreased. RT-qPCR studies also showed upregulation in the expression of p53 and caspase3 and downregulation in the expression of CDK2, Bcl-2 and Cyclin E genes. Molecular docking analysis displayed the interaction between BDCe fraction with p53 (−151.13 kcal/mol) and CDK1 (−133.96 kcal/mol). The results of the present work suggest that the BDCe fraction has chemopreventive properties against osteosarcoma (MG-63) cells through the induction of cell cycle arrest and apoptosis via Akt/NF-κB/p53 pathways. This study contributes to the understanding of the utilization of BDCe fraction in osteosarcoma treatment.

Molecular biological mechanism of action in cancer therapies: Juglone and its derivatives, the future of development

Juglone (5 - hydroxy - 1, 4 - naphthalene diketone) is a kind of natural naphthoquinone, present in the roots, leaves, nut-hulls, bark and wood of walnut trees. Recent studies have found that Juglone has special significance in the treatment of cancer, which plays a significant role in the resistance of cancer cell proliferation, induction of cancer cell apoptosis, induction of autophagy, anti-angiogenesis and inhibition of cancer cell migration and invasion, etc. Additionally, its derivatives also play a tumor suppressive effect. In conclusion, Juglone and its derivatives have been identified as effective anticancer drugs. This paper reviews action mechanisms of Juglone and its derivatives in cancer treatment.

Pre-Exposure to Stress-Inducing Agents Increase the Anticancer Efficacy of Focused Ultrasound against Aggressive Prostate Cancer Cells

Despite the initial success in treatment of localized prostate cancer (PCa) using surgery, radiation or hormonal therapy, recurrence of aggressive tumors dictates morbidity and mortality. Focused ultrasound (FUS) is being tested as a targeted, noninvasive approach to eliminate the localized PCa foci, and strategies to enhance the anticancer potential of FUS have a high translational value. Since aggressive cancer cells utilize oxidative stress (Ox-stress) and endoplasmic reticulum stress (ER-stress) pathways for their survival and recurrence, we hypothesized that pre-treatment with drugs that disrupt stress-signaling pathways in tumor cells may increase FUS efficacy. Using four different PCa cell lines, i.e., LNCaP, C4-2B, 22Rv1 and DU145, we tested the in vitro effects of FUS, alone and in combination with two clinically tested drugs that increase Ox-stress (i.e., CDDO-me) or ER-stress (i.e., nelfinavir). As compared to standalone FUS, significant (p < 0.05) suppressions in both survival and recurrence of PCa cells were observed following pre-sensitization with low-dose CDDO-me (100 nM) and/or nelfinavir (2 µM). In drug pre-sensitized cells, significant anticancer effects were evident at a FUS intensity of as low as 0.7 kW/cm². This combined mechanochemical disruption (MCD) approach decreased cell proliferation, migration and clonogenic ability and increased apoptosis/necrosis and reactive oxygen species (ROS) production. Furthermore, although activated in cells that survived standalone FUS, pre-sensitization with CDDO-me and/or nelfinavir suppressed both total and activated (phosphorylated) NF-κB and Akt protein levels. Thus, a combined MCD therapy may be a safe and effective approach towards the targeted elimination of aggressive PCa cells.

Core genes involved in the regulation of acute lung injury and their association with COVID-19 and tumor progression: A bioinformatics and experimental study

Acute lung injury (ALI) is a specific form of lung damage caused by different infectious and non-infectious agents, including SARS-CoV-2, leading to severe respiratory and systemic inflammation. To gain deeper insight into the molecular mechanisms behind ALI and to identify core elements of the regulatory network associated with this pathology, key genes involved in the regulation of the acute lung inflammatory response (Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Ptx3, Socs3) were revealed using comprehensive bioinformatics analysis of whole-genome microarray datasets, functional annotation of differentially expressed genes (DEGs), reconstruction of protein-protein interaction networks and text mining. The bioinformatics data were validated using a murine model of LPS-induced ALI; changes in the gene expression patterns were assessed during ALI progression and prevention by anti-inflammatory therapy with dexamethasone and the semisynthetic triterpenoid soloxolone methyl (SM), two agents with different mechanisms of action. Analysis showed that 7 of 8 revealed ALI-related genes were susceptible to LPS challenge (up-regulation: Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Socs3; down-regulation: Cat) and their expression was reversed by the pre-treatment of mice with both anti-inflammatory agents. Furthermore, ALI-associated nodal genes were analysed with respect to SARS-CoV-2 infection and lung cancers. The overlap with DEGs identified in postmortem lung tissues from COVID-19 patients revealed genes (Saa1, Rsad2, Ifi44, Rtp4, Mmp8) that (a) showed a high degree centrality in the COVID-19-related regulatory network, (b) were up-regulated in murine lungs after LPS administration, and (c) were susceptible to anti-inflammatory therapy. Analysis of ALI-associated key genes using The Cancer Genome Atlas showed their correlation with poor survival in patients with lung neoplasias (Ptx3, Timp1, Serpine1, Plaur). Taken together, a number of key genes playing a core function in the regulation of lung inflammation were found, which can serve both as promising therapeutic targets and molecular markers to control lung ailments, including COVID-19-associated ALI.

Pyomelanin produced by Streptomyces sp. ZL-24 and its protective effects against SH-SY5Y cells injury induced by hydrogen peroxide

A soluble melanin pigment produced by Streptomyces sp. ZL-24 was purified and named StrSM. The elemental analysis of StrSM showed it consists of carbon, hydrogen, and oxygen. The spectrum analysis, including ultraviolet-visible absorption spectrum, Fourier-transform infrared spectrum, and pyrolysis-gas chromatography-mass spectrometry, indicated that StrSM might be pyomelanin. High performance liquid chromatography and liquid chromatography-mass spectra analysis of intermediate metabolite showed the presence of homogentisic acid (HGA). Moreover, the enzyme 4-hydroxyphenylpyruvate dioxygenase, involved in HGA biosynthesis, showed high activity during melanin production. Subsequently, a tyrosinase gene (melC2) and hydroxyphenylpyruvate dioxygenase gene double mutant demonstrated StrSM is pyomelanin. In vitro bioactivity assay showed that StrSM had excellent protective capability against SH-SY5Y cell oxidative injury. To our knowledge, the results firstly provide comprehensive data on Streptomyces pyomelanin identification and a promising candidate compound to treat oxidative injury of neurocytes.

Growth inhibition and apoptosis of human multiple myeloma cells induced by 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid derivatives

Multiple myeloma is a blood cell cancer and can cause symptoms such as bone loss and fatigue. Recent studies have shown that the bone marrow microenvironment may mediate tumor proliferation, drug resistance, and migration of the multiple myeloma cells. Synthetic triterpenoids have been used for the treatment of cancer due to their antiproliferative and anti-inflammatory effects. The objective of this study is to examine the effect of 2-cyano-3, 12 dioxoolean-1,9-dien-28-oic acid (CDDO) derivatives on human multiple myeloma cells. Three CDDO derivatives, such as CDDO-methyl ester, CDDO-trifluroethyl amide, and CDDO-imidazolide (Im), were tested on the growth of human multiple myeloma cells. Our results show that all CDDO derivatives decrease the viability of multiple myeloma cells in a dose- and time-dependent manner, with CDDO-Im being the most potent. CDDO-Im was selected to investigate whether its inhibitory effect on multiple myeloma cell growth is due to cell cycle arrest and induction of apoptosis. The results suggest that CDDO-Im may inhibit cell cycle progression in the G0/G1 phase and induce the intrinsic apoptotic pathway. The effect of CDDO-Im on multiple myeloma cells was evaluated in a Transwell model using myeloma cells co-culturing with human HS-5 stromal cells to simulate the bone marrow microenvironment in vitro. The results showed that CDDO-Im induced multiple myeloma cell apoptosis in the presence of HS-5 cells, albeit to a lower extent than in multiple myeloma cells cultured alone. In conclusion, our data suggest that CDDO-Im inhibits the growth of multiple myeloma cells, either cultured alone or co-cultured with bone marrow stromal cells, through the induction of apoptosis.

Apigenin-Loaded PLGA-DMSA Nanoparticles: A Novel Strategy to Treat Melanoma Lung Metastasis

The flavone apigenin (APG), alone as well as in combination with other chemotherapeutic agents, is known to exhibit potential anticancer effects in various tumors and inhibit growth and metastasis of melanoma. However, the potential of apigenin nanoparticles (APG-NPs) to prevent lung colonization of malignant melanoma has not been well investigated. APG-loaded PLGA-NPs were surface-functionalized with meso-2,3-dimercaptosuccinic acid (DMSA) for the treatment of melanoma lung metastasis. DMSA-conjugated APG-loaded NPs (DMSA-APG-NPs) administered by an oral route exhibited sustained APG release and showed considerable enhancement of plasma half-life, C_max value, and bioavailability compared to APG-NPs both in plasma and the lungs. DMSA-conjugated APG-NPs showed comparably higher cellular internalization in B16F10 and A549 cell lines compared to that of plain NPs. Increased cytotoxicity was observed for DMSA-APG-NPs compared to APG-NPs in A549 cells. This difference between the two formulations was lower in B16F10 cells. Significant depolarization of mitochondrial transmembrane potential and an enhanced level of caspase activity were observed in B16F10 cells treated with DMSA-APG-NPs compared to APG-NPs as well. Western blot analysis of various proteins was performed to understand the mechanism of apoptosis as well as prevention of melanoma cell migration and invasion. DMSA conjugation substantially increased accumulation of DMSA-APG-NPs given by an intravenous route in the lungs compared to APG-NPs at 6 and 8 h. This was also corroborated by scintigraphic imaging studies with radiolabeled formulations administered by an intravenous route. Conjugation also allowed comparatively higher penetration as evident from an in vitro three-dimensional tumor spheroid model study. Finally, the potential therapeutic efficacy of the formulation was established in experimental B16F10 lung metastases, which suggested an improved bioavailability with enhanced antitumor and antimetastasis efficacy of DMSA-conjugated APG-NPs following oral administration.

Onosma bracteata Wall. induces G0/G1 arrest and apoptosis in MG-63 human osteosarcoma cells via ROS generation and AKT/GSK3β/cyclin E pathway

Onosma bracteata Wall. (Boraginaceae), commonly known as "gaozaban" is a highly valuable medicinal herb, useful in the treatment of body swellings, abdominal pain, eye-related problems, fever, and urinary calculi. The present study was performed to investigate the antioxidant properties of extract/fractions, viz. ethanol (Obeth) extract, hexane (Obhex) fraction, chloroform (Obcl) fraction, ethyl acetate (Obea) fraction, butanol (Obbu) fraction, and aqueous (Obaq) fraction isolated from O. bracteata. Obea fraction showed stronger free radical quenching ability in various antioxidant assays, as compared to the other fractions. Obea fraction with effective free radical-scavenging properties was further evaluated for the antiproliferative activity against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung cancer A549 cell lines using MTT assay. Obea fraction showed strong cytotoxicity with GI₅₀ value of 88.56, 101.61, and 112.7 μg/ml towards MG-63, IMR-32, and A549 cells respectively. Mechanistic studies revealed that Obea fraction in osteosarcoma MG-63 cells increased reactive oxygen species (ROS) level and reduced mitochondrial membrane potential. In the presence of Obea, the cells were found to be arrested in the G₀/G₁ phase in a dose-dependent manner which is also confirmed by the enhancement in the early apoptotic cell population in flow cytometer analysis. Western blotting demonstrated the decrease in expression of p-NFκB, COX-2, p-Akt, and Bcl-xL, whereas upregulation was observed in the expression of GSK-3β, p53, caspase-3, and caspase-9 proteins. RT-qPCR studies revealed downregulation of Bcl-2, cyclin E, CDK2, and mortalin gene expression and upregulation in the expression of p53 genes. The antioxidant and cytotoxic potential of Obea was attributed to the presence of catechin, kaempferol, onosmin A, and epicatechin, as revealed by HPLC analysis. This is the first report regarding the antiproliferative potential of O. bracteata against osteosarcoma.

Natural Compounds in Sex Hormone-Dependent Cancers: The Role of Triterpenes as Therapeutic Agents

Sex hormone-dependent cancers currently contribute to the high number of cancer-related deaths worldwide. The study and elucidation of the molecular mechanisms underlying the progression of these tumors was a double-edged sword, leading to the expansion and development of new treatment options, with the cost of triggering more aggressive, therapy resistant relapses. The interaction of androgen, estrogen and progesterone hormones with specific receptors (AR, ER, PR) has emerged as a key player in the development and progression of breast, ovarian, prostate and endometrium cancers. Sex hormone-dependent cancers share a common and rather unique carcinogenesis mechanism involving the active role of endogenous and exogenous sex hormones to maintain high mitotic rates and increased cell proliferation thus increasing the probability of aberrant gene occurrence and accumulation highly correlated with abnormal cell division and the occurrence of malignant phenotypes. Cancer related hormone therapy has evolved, currently being associated with the blockade of other signaling pathways often associated with carcinogenesis and tumor progression in cancers, with promising results. However, despite the established developments, there are still several shortcomings to be addressed. Triterpenes are natural occurring secondary metabolites biosynthesized by various pathways starting from squalene cyclization. Due to their versatile therapeutic potential, including the extensively researched antiproliferative effect, these compounds are most definitely a cornerstone in the research and development of new natural/semisynthetic anticancer therapies. The present work thoroughly describes the ongoing research related to the antitumor activity of triterpenes in sex hormone-dependent cancers. Also, the current review highlights both the biological activity of various triterpenoid compounds and their featured mechanisms of action correlated with important chemical structural features.

trans-Anethole Abrogates Cell Proliferation and Induces Apoptosis through the Mitochondrial-Mediated Pathway in Human Osteosarcoma Cells

trans-Anethole, the major bioactive component of Illicium verum Hook. commonly known as star anise exhibits various pharmacological activities including anti-inflammatory, antimicrobial, insecticidal, and antitumor. Osteosarcoma is an extremely aggressive malignant bone tumor that affects children and young adults and accounts for around 60% of all sarcomas. The study was planned to evaluate the potential of trans-Anethole against Human osteosarcoma cell line MG-63. The antiproliferative activity of trans-Anethole was assessed by MTT assay. trans-Anethole exhibited apoptotic cell death as monitored by confocal/electron microscopy and flow cytometry studies. Modulation of gene expression was studied by Western blot and RT-PCR analysis. The present study revealed that trans-Anethole inhibited osteosarcoma proliferation in a dose-dependent manner with a GI₅₀ value of 60.25 µM and showed pro-apoptotic activity as analyzed by Annexin V-FITC/PI assay. Flow cytometric analysis revealed that trans-Anethole induced cell cycle arrest at the G₀/G₁ phase with the generation of reactive oxygen species and reduction in mitochondrial membrane potential (ΔΨm). Immunoblotting results showed the increased expression of caspase-9/-3, p53, and decreased expression of Bcl-xL suggesting the involvement of the p53 and mitochondrial intrinsic pathway. This work provides a rationale that trans-Anethole might be considered as a promising chemotherapeutic/nutraceutical agent for the management of osteosarcoma.Highlightstrans-Anethole inhibited cell growth and caused G₀/G₁ arrest in Human osteosarcoma MG-63 cell line.trans-Anethole led to the loss of mitochondrial membrane permeability along with ROS generation.trans-Anethole upregulates the expression of p53, Caspase-9/-3, and downregulate Bcl-xL expression.

Repression of deoxynivalenol-triggered cytotoxicity and apoptosis by mannan/β-glucans from yeast cell wall: Involvement of autophagy and PI3K-AKT-mTOR signaling pathway

Deoxynivalenol (DON) is the most common trichothecene distributed in food and feed. So far, much work has focused on investigating the cytotoxicity of DON, while there is few researches aimed at intervening in the toxic impacts on humans and livestock posed by DON. The objective of this study is to investigate the underlying mechanism of biomacromolecules mannan/β-glucans from yeast cell wall (BYCW) for their potency to impede the cytotoxicity and apoptosis caused by DON with porcine jejunum epithelial cell lines (IPEC-J2) used as a cell injury model. We analyzed the cell morphology, cell activity, oxidative stress, fluorescence intensity and expressions of proteins relevant to autophagy, apoptosis and PI3K-AKT-mTOR signaling pathway by using inverted microscopy, MTS, reactive oxygen species (ROS), glutathione (GSH) and malondialdehyde (MDA) assay, Annexin V-FITC / propidium iodide (PI) double staining and Western blot assay. The consequent data demonstrated that in the presence of BYCW, the cell morphology and activity were relatively ameliorated and that the oxidation damage was attenuated with DON-induced autophagy concomitantly decreased, which, furthermore, was found involved in the positive regulation on PI3K-AKT-mTOR signaling pathway by BYCW. In a word, BYCW possess an ability to repress the cytotoxicity and apoptosis induced by DON through the inhibition of autophagy via activating PI3K-AKT-mTOR signaling pathway.

The role of natural products in revealing NRF2 function

Covering: up to 2020The transcription factor NRF2 is one of the body's major defense mechanisms, driving transcription of >300 antioxidant response element (ARE)-regulated genes that are involved in many critical cellular processes including redox regulation, proteostasis, xenobiotic detoxification, and primary metabolism. The transcription factor NRF2 and natural products have an intimately entwined history, as the discovery of NRF2 and much of its rich biology were revealed using natural products both intentionally and unintentionally. In addition, in the last decade a more sinister aspect of NRF2 biology has been revealed. NRF2 is normally present at very low cellular levels and only activated when needed, however, it has been recently revealed that chronic, high levels of NRF2 can lead to diseases such as diabetes and cancer, and may play a role in other diseases. Again, this "dark side" of NRF2 was revealed and studied largely using a natural product, the quassinoid, brusatol. In the present review, we provide an overview of NRF2 structure and function to orient the general reader, we will discuss the history of NRF2 and NRF2-activating compounds and the biology these have revealed, and we will delve into the dark side of NRF2 and contemporary issues related to the dark side biology and the role of natural products in dissecting this biology.

Andrographolide induces apoptosis in human osteosarcoma cells via the ROS/JNK pathway

Osteosarcoma is the most common primary malignant tumor of the bone and the long-term survival of patients with this disease has remained unsatisfactory over the past several decades. Andrographolide, a traditional drug used in Chinese medicine, has been found to exert a significant antitumor effect against several types of cancer. However, relatively little is known about the effect of andrographolide on osteosarcoma and the underlying mechanisms. In the present study, it was shown that andrographolide inhibited osteosarcoma cell proliferation by arresting the cell cycle at the G2/M phase and increasing caspase-mediated apoptosis. Furthermore, treatment with andrographolide induced JNK activation and increased production of reactive oxygen species (ROS). The andrographolide-triggered apoptosis in osteosarcoma cells was partly abrogated by a JNK inhibitor and completely reversed by a ROS scavenger. Additionally, JNK activation and cell cycle arrest at the G2/M phase were prevented by administration of an ROS scavenger. In vivo, it was also found that andrographolide inhibited tumor growth by increasing the levels of ROS and activating JNK; thus inducing cytotoxicity in primary osteosarcoma cells. Together, the results of the present study suggest that andrographolide caused G2/M arrest and induced cell apoptosis via regulation of the ROS/JNK signaling pathway in osteosarcoma cells. Thus, andrographolide may serve as a promising antitumor therapeutic agent against osteosarcoma.

Antioxidant, Antiproliferative and Apoptosis-Inducing Efficacy of Fractions from Cassia fistula L. Leaves

: Cassia fistula L. is a highly admirable traditional medicinal plant used for the treatment of various diseases and disorders. The present study was performed to divulge the antioxidant, antiproliferative, and apoptosis-inducing efficacy of fractions from C. fistula leaves. The hexane (CaLH fraction), chloroform (CaLC fraction), ethyl acetate (CaLE fraction), n-butanol (CaLB fraction), and aqueous (CaLA fraction) were sequentially fractionated from 80% methanolic (CaLM extract) of C. fistula leaves. The CaLE fraction was fractionated using column chromatography to yield a pure compound, which was characterized as Epiafzelechin (CFL1) based on 1H, 13C, and DEPT135 NMR. Among these fractions, CaLE and isolated CFL1 fractions exhibited an effective antioxidant potential in Ferric ion reducing power, (2,2'-azino-bis (3-ethylbenzothiazoline -6-sulfonic acid)) cation radical scavenging, and nitric oxide radical scavenging assays. Epiafzelechin was investigated for its antiproliferative effects against MG-63 (osteosarcoma), IMR-32 (neuroblastoma), and PC-3 (prostate adenocarcinoma), and was found to inhibit cell proliferation with a GI50 value of 8.73, 9.15, and 11.8 μM respectively. MG-63 cells underwent apoptotic cell death on treatment with Epiafzelechin as the cells showed the formation of apoptotic bodies, enhanced reactive oxygen species (ROS) generation, mitochondrial membrane depolarization along with an increase in early apoptotic cell population analyzed using Annexin V-FITC/PI double staining assay. Cells showed cell cycle arrest at the G0/G1 phase accompanied by a downregulation in the expression levels of p-Akt (Protein kinase B), p-GSK-3β (Glycogen synthase kinase-3 beta), and Bcl-xl (B-cell lymphoma-extra large) proteins. RT-PCR (Real time-polymerase chain reaction) analysis revealed downregulation in the gene expression level of β-catenin and CDK2 (cyclin-dependent kinases-2) while it upregulated the expression level of caspase-8 and p53 genes in MG-63 cells.

New ruthenium polypyridyl complexes functionalized with fluorine atom or furan: Synthesis, DNA-binding, cytotoxicity and antitumor mechanism studies

Two novel ruthenium(II) polypyridyl complexes, namely, [Ru(dmp)₂(CAPIP)](ClO₄)₂ (Ru(II)-1) and [Ru(dmp)₂(CFPIP)](ClO₄)₂ (Ru(II)-2), which respectively contain (E)-2-(2-(furan-2-yl)vinyl)-1H-imidazo[4,5-f][1,10]phen-anthroline (CAPIP) and (E)-2-(4-fluorostyryl)-1H-imidazo[4,5-f][1,10]phenanthroline. (CFPIP), were first designed and characterized (dmp = 2,9-dimethyl-1,10-phenanthroline). DNA binding experiments indicated that Ru(II) complexes interact with CT DNA through intercalative mode. In addition, the complexes Ru(II)-1 and Ru(II)-2, showed remarkable cell cytotoxicity, giving the respective IC₅₀ values of 4.1 ± 1.4 μM and 6.1 ± 1.4 μM on the A549 cancer cells. These values indicated higher activity than CAPIP, CFPIP, cisplatin (8.2 ± 1.4 μM) and other corresponding Ru(II) polypyridyl complexes. Furthermore, the Ru(II) complexes could arrive the cytoplasm through the cell membrane and accumulate in the mitochondria. Significantly, complexes Ru(II)-1 and Ru(II)-2 induced A549 cells apoptosis was mediated by increase of ROS levels and dysfunction of mitochondria, and resulted in cell cycle arrest and increased anti-migration activity on A549 cells. Overall, these results indicated that complexes Ru(II)-1 and Ru(II)-2 could be suitable candidates for further investigation as a chemotherapeutic agent in the treatment of tumors.

Deoxynivalenol-Induced Cytotoxicity and Apoptosis in IPEC-J2 Cells Through the Activation of Autophagy by Inhibiting PI3K-AKT-mTOR Signaling Pathway

With the purpose to explore the relationship between deoxynivalenol (DON)-induced apoptosis and autophagy and provide mechanistic explanations for the toxic effects of DON on IPEC-J2 cells, we determined the cell viability, cell morphology, apoptosis, and autophagy by using autophagy inhibitor 3-methyladenine (3-MA), PI3K pathway inhibitor LY294002, and activator 740Y-P. It turned out that 3-MA was able to attenuate the reduction of cell viability induced by DON. Moreover, 3-MA was capable of upregulating the expression of DON-induced autophagic protein p62 and downregulating the expressions of DON-induced autophagic protein LC3-II and apoptotic protein Bax, suggesting that autophagy is a driving mechanism for this apoptotic induction. The results of Annexin V-FITC/PI double staining indicated that DON could induce apoptosis by inhibiting the PI3K-AKT-mTOR signaling pathway. Subsequently, it was further confirmed by Western blot analysis that DON significantly decreased expressions of P-AKT/AKT, p-mTOR/mTOR, and autophagic protein p62, and increased expression of autophagy-related protein LC3-II, suggesting that DON triggered autophagy by inhibiting the PI3K-AKT-mTOR signaling pathway. To conclude, these data reveal that DON may induce cytotoxicity and apoptosis through the activation of autophagy by suppressing the PI3K-AKT-mTOR signaling pathway. This study provides new insights into the mechanisms by which DON incurs cytotoxic effects.

Deep insights into the response of human cervical carcinoma cells to a new cyano enone-bearing triterpenoid soloxolone methyl: a transcriptome analysis

Semisynthetic triterpenoids, bearing cyano enone functionality in ring A, are considered now as novel promising anti-tumor agents. However, despite the large-scale studies, their effects on cervical carcinoma cells and, moreover, mechanisms underlying cell death activation by such compounds in this cell type have not been fully elucidated. In this work, we attempted to reconstitute the key pathways and master regulators involved in the response of human cervical carcinoma KB-3-1 cells to the novel glycyrrhetinic acid derivative soloxolone methyl (SM) by a transcriptomic approach. Functional annotation of differentially expressed genes, analysis of their cis^- regulatory sequences and protein-protein interaction network clearly indicated that stress of endoplasmic reticulum (ER) is the central event triggered by SM in the cells. A range of key ER stress sensors and transcription factor AP-1 were identified as upstream transcriptional regulators, controlling the response of the cells to SM. Additionally, by using Gene Expression Omnibus data, we showed the ability of SM to modulate the expression of key genes involved in regulation of the high proliferative rate of cervical carcinoma cells. Further Connectivity Map analysis revealed similarity of SM's effects with known ER stress inducers thapsigargin and geldanamycin, targeting SERCA and Grp94, respectively. According to the molecular docking study, SM could snugly fit into the active sites of these proteins in the positions very close to that of both inhibitors. Taken together, our findings provide a basis for the better understanding of the intracellular processes in tumor cells switched on in response to cyano enone-bearing triterpenoids.

RTA 408 Inhibits Interleukin-1β-Induced MMP-9 Expression via Suppressing Protein Kinase-Dependent NF-κB and AP-1 Activation in Rat Brain Astrocytes

Neuroinflammation is characterized by the elevated expression of various inflammatory proteins, including matrix metalloproteinases (MMPs), induced by various pro-inflammatory mediators, which play a critical role in neurodegenerative disorders. Interleukin-1β (IL-1β) has been shown to induce the upregulation of MMP-9 through nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)-reactive oxygen species (ROS)-dependent signaling pathways. N-(2-cyano-3,12-dioxo-28-noroleana-1,9(11)-dien-17-yl)-2-2-difluoropropanamide (RTA 408), a novel synthetic triterpenoid, has been shown to possess anti-oxidant and anti-inflammatory properties in various types of cells. Here, we evaluated the effects of RTA 408 on IL-1β-induced inflammatory responses by suppressing MMP-9 expression in a rat brain astrocyte (RBA-1) line. IL-1β-induced MMP-9 protein and mRNA expression, and promoter activity were attenuated by RTA 408. The increased level of ROS generation in RBA-1 cells exposed to IL-1β was attenuated by RTA 408, as determined by using 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) and CellROX. In addition, the inhibitory effects of RTA 408 on MMP-9 expression resulted from the suppression of the IL-1β-stimulated activation of Pyk2 (proline-rich tyrosine kinase), platelet-derived growth factor receptor β (PDGFRβ), Akt, ROS, and mitogen-activated protein kinases (MAPKs). Pretreatment with RTA 408 attenuated the IL-1β-induced c-Jun phosphorylation, mRNA expression, and promoter activity. IL-1β-stimulated nuclear factor-κB (NF-κB) p65 phosphorylation, translocation, and promoter activity were also attenuated by RTA 408. Furthermore, IL-1β-induced glial fibrillary acidic protein (GFAP) protein and mRNA expression, and cell migration were attenuated by pretreatment with RTA 408. These results provide new insights into the mechanisms by which RTA 408 attenuates IL-1β-mediated inflammatory responses and exerts beneficial effects for the management of brain diseases.

FPOA induces apoptosis in HeLa human cervical cancer cells through a caspase-mediated pathway

In the present study, the triterpenoid 3-acetoxylanosta-8,24-dien-21-oic acid (FPOA) was extracted from Fomitopsis pinicola. The aim of the present was to elucidate the mechanism of action of FPOA in HeLa cervical cancer cells. Cell viability was examined using an MTT assay and the morphological detection of apoptosis was conducted using DAPI staining. The rate of apoptosis was examined via Annexin V-FITC/PI double staining and the expression levels of apoptosis-associated proteins were determined by western blot analysis. FPOA was observed to inhibit HeLa cell proliferation, with IC₅₀ values of 25.28, 15.30 and 11.79 µg/ml at 24, 48 and 72 h, respectively. Typical apoptotic bodies were observed in the HeLa cells following treatment with FPOA, as revealed by DAPI staining. The percentage of apoptotic cells was 3.00, 3.12, 6.18 and 32.28% following treatment with FPOA at concentrations of 0, 7.5, 15 and 30 µg/ml, respectively. Western blot analysis showed that caspase-3 and −9 were cleaved more frequently after treatment with FPOA. Furthermore, the expression of Bax was increased but Bcl-2 expression was decreased after treatment with FPOA. These results suggest that FPOA can induce HeLa cell apoptosis through a caspase-mediated pathway.

Pseudo-Ginsenoside Rh2 induces A549 cells apoptosis via the Ras/Raf/ERK/p53 pathway

Ginsenoside Rh2, a major effective constituent of ginseng, has been suggested to have a pro-apoptotic effect in a variety of cancer cells. Pseudo-Ginsenside-Rh2 (pseudo-G-Rh2) is a novel derivative of ginsenoside Rh2. The aim of the present study was to evaluate the effect of pseudo-G-Rh2 on the apoptosis of lung adenocarcinoma A549 cells. The cytotoxicity of pseudo-G-Rh2 on A549 cells was evaluated using an MTT assay. Apoptosis was detected using DAPI staining and flow cytometry. The expression of apoptosis associated proteins was identified by western blot analysis. The results demonstrated that pseudo-G-Rh2 inhibits the proliferation of A549 cells in a dose-dependent manner. DAPI staining revealed topical morphological changes in apoptotic bodies following pseudo-G-Rh2 treatment. Flow cytometric analysis revealed that the percentage of Annexin V-fluorescein isothiocyanate-positive cells, which are apoptotic, increased with pseudo-G-Rh2 treatment in a dose-dependent manner. Furthermore, treatment with pseudo-G-Rh2 increased the level of reactive oxygen species in A549 cells as well as the activation of caspase-9, caspase-3 and poly ADP-ribose polymerase. Pseudo-G-Rh2 treatment was observed to induce mitochondrial membrane potential loss. Furthermore, the results of western blotting revealed that B-cell lymphoma 2 (Bcl-2) expression was significantly decreased while Bcl-2-associated X protein expression was significantly upregulated in A549 cells with pseudo-G-Rh2 treatment. Pseudo-G-Rh2-induced apoptosis was accompanied by sustained phosphorylation of Ras, Raf, extracellular signal-regulated kinase (ERK) and p53. In conclusion, the results of the present study suggest that pseudo-G-Rh2 induces mitochondrial apoptosis in A549 cells and is responsible for excessive activation of the Ras/Raf/ERK/p53 pathway.

Bardoxolone methyl induces neuritogenesis in Neuro2a cells

BACKGROUND

Bardoxolone methyl (RTA 402, CDDOMe) has been long known for its anti-inflammatory and exceptional cytotoxic activity. The biological responses to CDDOMe are truly dose dependent. And owing to the structural modifications introduced in its parent molecule oleanolic acid, CDDOMe is able to form reversible adducts with cellular proteins containing redox sensitive cysteine residues. This nature of CDDOMe makes it a multifunctional molecule targeting multiple signaling pathways. This study was initiated to study the response of Neuro2a, a mouse neuroblastoma cell line to CDDOMe.

METHODS

Neuro2a cells were treated with CDDOMe and all trans retinoic acid (ATRA) for 4days and observed for neurite outgrowth. The neurite length was estimated using ImageJ software (Neuron growth plugin). Cell viability was investigated using MTT dye reduction and trypan blue dye exclusion method. Gene expression of differentiation markers was analyzed using quantitative PCR. Cellular localization of Tuj1 and synaptophysin in differentiated Neuro2a cells was observed using immunofluorescence.

RESULTS

CDDOMe ceased proliferation and induced dramatic neurite outgrowth in Neuro2a cells. These morphological changes were accompanied by time dependent increase in the mRNA levels of tyrosine hydroxylase, neurofilament 200 and synaptophysin. Besides, cytoskeleton protein Tuj1 and the synaptic vesicle protein synaptophysin were also observed to be localized in the neurites induced by CDDOMe.

CONCLUSIONS

These early shreds of evidence suggest that CDDOMe induces differentiation in Neuro2a cells at concentrations ranging from 0.2 to 0.4μM and indeed contributes the existing knowledge on CDDOMe induced activities in cells.

Molecular links among non-biodegradable nanoparticles, reactive oxygen species, and autophagy

For nanoparticles to be successful in combating diseases in the clinic in the 21st century and beyond, they must localize to target areas of the body and avoid damaging non-target, healthy tissues. Both soft and stiff, bio-degradable and non-biodegradable nanoparticles are anticipated to be used to this end. It has been shown that stiff, non-biodegradable nanoparticles cause reactive oxygen species (ROS) generation and autophagy in a variety of cell lines in vitro. Both responses can lead to significant remodeling of the cytosol and even apoptosis. Thus these are crucial cellular functions to understand. Improved assays have uncovered crucial roles of the Akt/mTOR signaling pathway in both ROS generation and autophagy initiation after cells have internalized stiff, non-biodegradable nanoparticles over varying geometries in culture. Of particular - yet unresolved - interest is how these nanoparticles cause the activation of these pathways. This article reviews the most recent advances in nanoparticle generation of ROS and autophagy initiation with a focus on stiff, non-biodegradable technologies. We provide experimental guidelines to the reader for fleshing out the effects of their nanoparticles on the above pathways with the goal of tuning nanoparticle design.

Betulinic acid induces apoptosis by regulating PI3K/Akt signaling and mitochondrial pathways in human cervical cancer cells

Betulinic acid (BA), a potential anticancer compound, could induce apoptosis in human cervical cancer (HeLa) cells, but its mechanism has yet to be fully elucidated. The present study was focused on deciphering the detailed molecular mechanism of BA-induced apoptosis. In the present study, results indicated that BA was highly effective against HeLa cells via induction of time-dependent apoptosis, and the authors demonstrated that the BA treatment acted through downregulating a phosphatidylinositol 3-kinase (PI3K) subunit and suppressing the Akt phosphorylation at Thr308 and Ser473 after increasing the generation of intracellular reactive oxygen species. Then, BA induced cell cycle arrest at the G0/G1 phase, which was consistent with the cell cycle-related protein results in which BA significantly enhanced the expression of p27Kip and p21Waf1/Cip1 in HeLa cells. This target-specific inhibition was associated with mitochondrial apoptosis, as reflected by the increased expression of Bad and caspase-9, the generation of reactive oxygen species (ROS) and the decline in mitochondrial membrane potential. Moreover, preincubation of the cells with glutathione (antioxidant) blocked the process of apoptosis, prevented the phosphorylation of downstream substrates. These results established that ROS acted as a key factor to effect apoptosis by BA treatment in HeLa cells. Therefore, these findings demonstrated that BA induced apoptosis in HeLa cells by downregulating the expression of PI3K/Akt signaling molecules via ROS, and triggering a mitochondrial pathway.

Combined targeting of STAT3 and STAT5: a novel approach to overcome drug resistance in chronic myeloid leukemia

In chronic myeloid leukemia, resistance against BCR-ABL1 tyrosine kinase inhibitors can develop because of BCR-ABL1 mutations, activation of additional pro-oncogenic pathways, and stem cell resistance. Drug combinations covering a broad range of targets may overcome resistance. CDDO-Me (bardoxolone methyl) is a drug that inhibits the survival of leukemic cells by targeting different pro-survival molecules, including STAT3. We found that CDDO-Me inhibits proliferation and survival of tyrosine kinase inhibitor-resistant BCR-ABL1⁺ cell lines and primary leukemic cells, including cells harboring BCR-ABL1^T315I or T315I⁺ compound mutations. Furthermore, CDDO-Me was found to block growth and survival of CD34⁺/CD38⁻ leukemic stem cells (LSC). Moreover, CDDO-Me was found to produce synergistic growth-inhibitory effects when combined with BCR-ABL1 tyrosine kinase inhibitors. These drug-combinations were found to block multiple signaling cascades and molecules, including STAT3 and STAT5. Furthermore, combined targeting of STAT3 and STAT5 by shRNA and STAT5-targeting drugs also resulted in synergistic growth-inhibition, pointing to a new efficient concept of combinatorial STAT3 and STAT5 inhibition. However, CDDO-Me was also found to increase the expression of heme-oxygenase-1, a heat-shock-protein that triggers drug resistance and cell survival. We therefore combined CDDO-Me with the heme-oxygenase-1 inhibitor SMA-ZnPP, which also resulted in synergistic growth-inhibitory effects. Moreover, SMA-ZnPP was found to sensitize BCR-ABL1⁺ cells against the combination ‘CDDO-Me+ tyrosine kinase inhibitor’. Together, combined targeting of STAT3, STAT5, and heme-oxygenase-1 overcomes resistance in BCR-ABL1⁺ cells, including stem cells and highly resistant sub-clones expressing BCR-ABL1^T315I or T315I-compound mutations. Whether such drug-combinations are effective in tyrosine kinase inhibitor-resistant patients with chronic myeloid leukemia remains to be elucidated.

Triterpenoid Acids as Important Antiproliferative Constituents of European Elderberry Fruits

In Europe, both the fruits and flowers of Sambucus nigra L. have been used against cold, as well as laxative, diaphoretic, and diuretic remedies. There are also a number of commercially available food products that contain elderberry juice, puréed or dried elderberries. Recent comprehensive literature data on pharmacology and chemistry of Sambuci fructus have encouraged us to screen extracts with different polarities from this plant material against cancer cell lines. The cytotoxic activity of the ethyl acetate and aqueous acetone extracts from elderberries as well as detected triterpenoids on human colon adenocarcinoma cell line (LoVo) and human breast cancer cell line (MCF-7) was investigated by sulforhodamine B assay. Moreover, cell migration assay was conducted for triterpenoid fraction and pure compounds. Aqueous acetone extract possessed much lower IC50 value in cancer cell lines compared to ethyl acetate extract. The latter manifested high cytotoxicity against studied cell lines, suggesting that nonpolar compounds are responsible for the cytotoxic activity. Indeed, the phytochemical analysis revealed that ursolic and oleanolic acids are the main triterpenoids in the mentioned extract of which ursolic acid showed the highest activity with IC50 values of 10.7 µg/mL on MCF-7 and 7.7 µg/mL on LoVo cells.

Increased Intracellular Reactive Oxygen Species Mediates the Anti-Cancer Effects of WZ35 via Activating Mitochondrial Apoptosis Pathway in Prostate Cancer Cells

BACKGROUND

The limited treatment option for recurrent prostate cancer and eventual resistant to conventional chemotherapy drugs has fueled continued interest in finding new anti-neoplastic agents. WZ35, a chemical analog of curcumin, had been demonstrated to have high chemical stability and potential anticancer effects in gastric cancer cells. The present study aimed to investigate the anti-prostate cancer effects of WZ35 in vitro and in vivo as well as the underlying mechanism.

METHODS

Two prostate cancer cell lines RM-1 and DU145 were utilized to test the anti-cancer effects of WZ35 and the underlying mechanism. MTT assay was used to assess the cytotoxic effect of WZ35. Cell cycle distribution, apoptosis, alteration of ROS, and [Ca²⁺ ]_i level were evaluated using flow cytometry. Western blotting assay was applied to measure the levels of proteins associated with apoptosis and cell cycle. Immunofluorescence staining and Electron micrographs were used to evaluate activation of mitochondrial apoptosis pathway. Tumor models in nude mice were induced by injection of RM-1 prostate cancer cells to test the in vivo anticancer action of WZ35.

RESULTS

Our results showed that WZ35 treatment induced loss of cell viability, cell apoptosis, and G2/M cycle arrest in both RM-1 and DU145 cells, coupled with ROS overproduction, intracellular calcium surge, and activation of mitochondrial apoptosis pathway in RM-1 cells. Interestingly, all above changes induced by WZ35 were completely reversed by ROS blockage. In addition, prevention of [Ca²⁺ ]_i elevation by BAPTA/AM also inhibited activation of mitochondrial apoptosis pathway induced by WZ35. In vivo studies, WZ35 treatment significantly inhibited RM-1 homograft tumor growth along with increased ROS accumulation, mitochondrial disruption, and cell apoptosis in tumor tissues.

CONCLUSIONS

In conclusion, this work provides a novel anticancer candidate for the treatment of prostate cancer and demonstrated that increased ROS mediate the anti-cancer effects of WZ35 via activating mitochondrial apoptosis pathway. Importantly, this work also reveals that targeting ROS generation might be an effective strategy in human androgen-resistant prostate cancer treatment. Prostate 77:489-504, 2017. © 2016 Wiley Periodicals, Inc.

Oleanolic acid inhibits cell survival and proliferation of prostate cancer cells in vitro and in vivo through the PI3K/Akt pathway

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid and possesses diverse pharmacological activities, including anti-cancer effects that have been confirmed in multiple types of human cancers. However, the potential effect of natural OA on human prostate cancer is still unclear. The present study aimed to explore whether and how OA exerted anti-cancer effects in prostate cancer. Our data showed that OA inhibited cell viability and proliferation, and promoted cell apoptosis and G0/G1 phase cell cycle arrest in prostate cancer PC-3, DU145, and LNCaP cells, in a dose-dependent manner. In addition, OA was found to regulate the expression levels of apoptosis-related and cell cycle-related proteins, as well as the activity of PI3K/Akt pathway, in a dose-dependent manner. Mechanistically, our data revealed that OA exerted anti-cancer effects in vitro in PC-3 and DU145 cells by repressing the PI3K/Akt pathway. In agreement, OA also suppressed the tumor growth of PC-3 cells in vivo via inhibition of the PI3K/Akt pathway. In conclusion, our findings demonstrate the anti-cancer properties of OA in prostate cancer cells, both in vitro and in vivo, and provide the experimental evidence for the use of OA as an adjuvant agent for prostate cancer patients.

Oxidative Stress Attenuates Lipid Synthesis and Increases Mitochondrial Fatty Acid Oxidation in Hepatoma Cells Infected with Hepatitis C Virus

Cytopathic effects are currently believed to contribute to hepatitis C virus (HCV)-induced liver injury and are readily observed in Huh7.5 cells infected with the JFH-1 HCV strain, manifesting as apoptosis highly correlated with growth arrest. Reactive oxygen species, which are induced by HCV infection, have recently emerged as activators of AMP-activated protein kinase. The net effect is ATP conservation via on/off switching of metabolic pathways that produce/consume ATP. Depending on the scenario, this can have either pro-survival or pro-apoptotic effects. We demonstrate reactive oxygen species-mediated activation of AMP-activated kinase in Huh7.5 cells during HCV (JFH-1)-induced growth arrest. Metabolic labeling experiments provided direct evidence that lipid synthesis is attenuated, and β-oxidation is enhanced in these cells. A striking increase in nuclear peroxisome proliferator-activated receptor α, which plays a dominant role in the expression of β-oxidation genes after ligand-induced activation, was also observed, and we provide evidence that peroxisome proliferator-activated receptor α is constitutively activated in these cells. The combination of attenuated lipid synthesis and enhanced β-oxidation is not conducive to lipid accumulation, yet cellular lipids still accumulated during this stage of infection. Notably, the serum in the culture media was the only available source for polyunsaturated fatty acids, which were elevated (2-fold) in the infected cells, implicating altered lipid import/export pathways in these cells. This study also provided the first in vivo evidence for enhanced β-oxidation during HCV infection because HCV-infected SCID/Alb-uPA mice accumulated higher plasma ketones while fasting than did control mice. Overall, this study highlights the reprogramming of hepatocellular lipid metabolism and bioenergetics during HCV infection, which are predicted to impact both the HCV life cycle and pathogenesis.

Redox signaling: Potential arbitrator of autophagy and apoptosis in therapeutic response

Redox signaling plays important roles in the regulation of cell death and survival in response to cancer therapy. Autophagy and apoptosis are discrete cellular processes mediated by distinct groups of regulatory and executioner molecules, and both are thought to be cellular responses to various stress conditions including oxidative stress, therefore controlling cell fate. Basic levels of reactive oxygen species (ROS) may function as signals to promote cell proliferation and survival, whereas increase of ROS can induce autophagy and apoptosis by damaging cellular components. Growing evidence in recent years argues for ROS that below detrimental levels acting as intracellular signal transducers that regulate autophagy and apoptosis. ROS-regulated autophagy and apoptosis can cross-talk with each other. However, how redox signaling determines different cell fates by regulating autophagy and apoptosis remains unclear. In this review, we will focus on understanding the delicate molecular mechanism by which autophagy and apoptosis are finely orchestrated by redox signaling and discuss how this understanding can be used to develop strategies for the treatment of cancer.

Protective effects of ginsenoside Rg2 against H2O2-induced injury and apoptosis in H9c2 cells

Ginsenoside Rg2 is one of the major active components of ginseng and has many biological activities. This study aimed to investigate the protective effects of ginsenoside Rg2 against H2O2-induced injury and apoptosis in H9c2 cells. The results showed that pretreatment with ginsenoside Rg2 not only increased cell viability, but also decreased lactate dehydrogenase (LDH) release. Ginsenoside Rg2 inhibited the decrease of SOD, GSH-PX activities and the increase of MDA content induced by H2O2. Meanwhile, the levels of ROS generation and cardiomyocyte apoptosis in ginsenoside Rg2 group significantly reduced when compared with the model group. Western blot analyses demonstrated that ginsenoside Rg2 up-regulate level of Bcl-2 expression and down-regulate levels of Bax, Caspase-3, -9 expression. These findings indicated that ginsenoside Rg2 could protect H9c2 cells against H2O2-induced injury through its actions of anti-oxidant and anti-apoptosis.

The Synthetic Triterpenoid RTA 405 (CDDO-EA) Halts Progression of Liver Fibrosis and Reduces Hepatocellular Carcinoma Size Resulting in Increased Survival in an Experimental Model of Chronic Liver Injury

Patients with cirrhosis have an increased risk of developing liver cancer and a higher rate of mortality. Cirrhosis currently has no known cure, and patients may benefit from new agents aimed at alleviating their complications and slowing down the rate of disease progression. Therefore, the effects of the orally bioavailable synthetic triterpenoid 2-cyano-3,12-dioxooleana- 1,9(11)-dien-28-oate-ethyl amide (CDDO-EA, RTA 405), which has potent antioxidative and antiinflammatory properties, was evaluated in a chronic carbon tetrachloride (CCl(4))-induced model of liver cirrhosis and hepatocellular carcinoma (HCC). Mice were injected with CCl(4) (to induce fibrosis and cirrhosis) or placebo biweekly for 12 weeks followed by CDDO-EA in the diet for 18 weeks with continued biweekly injections of CCl(4). Chronic CCl(4) administration resulted in cirrhosis, ascites, and HCC formation, associated with increased serum transforming growth factor-β1, hepatic hydroxyproline content, and increased serum bilirubin. CDDO-EA, whose administration commenced after establishment of liver fibrosis, decreased liver fibrosis progression, serum bilirubin, ascites, and HCC formation and markedly increased overall survival. CDDO-EA also attenuated -TNFα (tumor necrosis factor-α), α-SMA (alpha smooth muscle actin), augmented -IL-10 levels, and improved histologic and serologic markers of fibrosis.

CONCLUSIONS

CDDO-EA mitigates the progression of liver fibrosis induced by chronic CCl(4) administration, which is associated with the induction of antifibrogenic genes and suppression of profibrogenic genes.

The effect of ex vivo CDDO-Me activation on nuclear factor erythroid 2-related factor 2 pathway in white blood cells from patients with septic shock

Nuclear factor erythroid 2-related factor 2 (NRF2) has been shown to protect against experimental sepsis in mice and lipopolysaccharide (LPS)-induced inflammation in ex vivo white blood cells from healthy subjects by upregulating cellular antioxidant genes. The objective of this study was to test the hypothesis that ex vivo methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate (CDDO-Me) activates NRF2-regulated antioxidant genes in white blood cells from patients with septic shock and protects against LPS-induced inflammation and reactive oxidative species production. Peripheral blood was collected from 18 patients with septic shock who were being treated in medical and surgical intensive care units. Real-time polymerase chain reaction was used to quantify the expression of NRF2 target genes (NQO1, HO-1, GCLM, and FTL) and IL-6 in peripheral blood mononuclear cells (PBMCs), monocytes, and neutrophils after CDDO-Me treatment alone or after subsequent LPS exposure. Superoxide anion (O2) was measured to assess the effect of CDDO-Me pretreatment on subsequent LPS exposure. Treatment with CDDO-Me increased the gene expression of NQO1 (P = 0.04) and decreased the expression of HO-1 (P = 0.03) in PBMCs from patients with septic shock. Purified monocytes exhibited significant increases in the expression of NQO1 (P = 0.01) and GCLM (P = 0.003) after CDDO-Me treatment. Levels of other NRF2 target genes (HO-1 and FTL) remained similar to those of vehicle-treated cells. Peripheral blood mononuclear cells showed a trend toward increased IL-6 gene expression after CDDO-Me treatment, whereas purified monocytes showed a trend toward decreased IL-6. There was no discernible trend in the IL-6 expression subsequent to LPS treatment in either vehicle-treated or CDDO-Me-treated PBMCs and monocytes. Treatment with CDDO-Me significantly increased O2 production in PBMCs (P = 0.04). Although CDDO-Me pretreatment significantly attenuated O2 production to subsequent LPS exposure (P = 0.03), the change was comparable to that observed in vehicle-treated PBMCs. Pretreatment with CDDO-Me followed by LPS exposure had no significant effect on O2 levels in purified monocytes. These data suggest that the NRF2 pathway is differentially responsive to CDDO-Me activation in peripheral blood cells from patients with septic shock and results in increased O2 production. The data may also suggest a suppressed NRF2 pathway in white blood cells from critically ill patients.

Antiproliferative and Apoptosis Inducing Effects of Non-Polar Fractions from Lawsonia inermis L. in Cervical (HeLa) Cancer Cells

Two non-polar fractions viz. hexane (Hex-LI) and chloroform fraction (CHCl3-LI) of Lawsonia inermis were studied for their antiproliferative potential in various cancer cell lines viz. HeLa, MCF-7, A549 and C6 glioma cells. Both the fractions showed more than 60 % of growth inhibition in all the tested cell lines at highest tested concentration. In clonogenic assay, different concentrations of Hex-LI and CHCl3-LI decreased the number and size of colonies as compared to control in HeLa cells. The apoptotic effects as nuclear condensation, fragmentation were visualized with Hoechst-33342 staining of HeLa cells using confocal microscope. Both fractions induced apoptotic cell death in human cervical carcinoma (HeLa) cells as evident from flow cytometric analysis carried out using Annexin V-FITC and propidium iodide dyes. CHCl3-LI treated cells significantly induced apoptosis (25.43 %) in comparison to control. Results from Neutral Comet assay demonstrated that both fractions induced double stranded breaks (DSB's) in HeLa cells. Our data indicated that Hex-LI and CHCl3-LI treated cells showed significant increase of 32.2 and 18.56 % reactive oxygen species (ROS) levels in DCFH-DA assay respectively. Further, experimental studies to decipher exact pathway via which these fractions induce cell death are in progress.

Bardoxolone methyl induces apoptosis and autophagy and inhibits epithelial-to-mesenchymal transition and stemness in esophageal squamous cancer cells

Natural and synthetic triterpenoids have been shown to kill cancer cells via multiple mechanisms. The therapeutic effect and underlying mechanism of the synthetic triterpenoid bardoxolone methyl (C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid; CDDO-Me) on esophageal cancer are unclear. Herein, we aimed to investigate the anticancer effects and underlying mechanisms of CDDO-Me in human esophageal squamous cell carcinoma (ESCC) cells. Our study showed that CDDO-Me suppressed the proliferation and arrested cells in G₂/M phase, and induced apoptosis in human ESCC Ec109 and KYSE70 cells. The G₂/M arrest was accompanied with upregulated p21Waf1/Cip1 and p53 expression. CDDO-Me significantly decreased B-cell lymphoma-extra large (Bcl-xl), B-cell lymphoma 2 (Bcl-2), cleaved caspase-9, and cleaved poly ADP ribose polymerase (PARP) levels but increased the expression level of Bcl-2-associated X (Bax). Furthermore, CDDO-Me induced autophagy in both Ec109 and KYSE70 cells via suppression of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway. There were interactions between the autophagic and apoptotic pathways in Ec109 and KYSE70 cells subject to CDDO-Me treatment. CDDO-Me also scavenged reactive oxygen species through activation of the nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) pathway in Ec109 and KYSE70 cells. CDDO-Me inhibited cell invasion, epithelial–mesenchymal transition, and stemness in Ec109 and KYSE70 cells. CDDO-Me significantly downregulated E-cadherin but upregulated Snail, Slug, and zinc finger E-box-binding homeobox 1 (TCF-8/ZEB1) in Ec109 and KYSE70 cells. CDDO-Me significantly decreased the expression of octamer-4, sex determining region Y-box 2 (Sox-2), Nanog, and B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1), all markers of cancer cell stemness, in Ec109 and KYSE70 cells. Taken together, these results indicate that CDDO-Me is a promising anticancer agent against ESCC. Further studies are warranted to explore the molecular targets, efficacy and safety of CDDO-Me in the treatment of ESCC.

Antioxidant enzyme inhibitor role of phosphine metal complexes in lung and leukemia cell lines

Phosphine metal complexes have been recently evaluated in the field of cancer therapy. In this research, the cytotoxic effects of some metal phosphines {[PdCl2((CH2OH)2PCH2)2NCH3] (C1), [RuCl2(((CH2OH)2PCH2)2NCH3)2] (C2), [PtCl2((Ph2PCH2)2NCH3)(timin)2] (C3)} on K562 (human myelogenous leukemia cell line) and A549 (adenocarcinomic human alveolar basal epithelial cells) cells were investigated using the MTT test. C1 and C2 are water-soluble metal complexes, which may have some advantages in in vitro and in vivo studies. The effects of the above-mentioned metal complexes on thioredoxin reductase (TrxR) (EC: 1.8.1.9), glutathione peroxidase (GPx) (EC: 1.11.1.9), and catalase (Cat) (EC: 1.11.1.6) enzymes were also tested. The results of this research showed that all three metal complexes indicated dose-dependent cytotoxicity on A549 and K562 cell lines and that the complexes inhibited different percentages of the TrxR, GPx, and Cat enzymes of these tumor cells.

Radiation protection of the gastrointestinal tract and growth inhibition of prostate cancer xenografts by a single compound

Normal tissue toxicity markedly reduces the therapeutic index of genotoxic anticancer agents, including ionizing radiation. Countermeasures against tissue damage caused by radiation are limited by their potential to also protect malignant cells and tissues. Here, we tested a panel of signal transduction modifiers for selective radioprotection of normal but not tumor tissues. These included three inhibitors of GSK3 (LiCl, SB216763, and SB415286) and two inhibitors of NF-κB (ethyl pyruvate and RTA 408). Among these, the thiol-reactive triterpenoid RTA 408 emerged as a robust and effective protector of multiple organ systems (gastrointestinal, skin, and hemopoietic) against lethal doses of radiation. RTA 408 preserved survival and proliferation of intestinal crypt cells in lethally irradiated mice while reducing apoptosis incidence in crypts and villi. In contrast, RTA 408 uniformly inhibited growth of established CWR22Rv1, LNCaP/C4-2B, PC3, and DU145 xenografts either alone or combined with radiation. Antitumor effects in vivo were associated with reduced proliferation and intratumoral apoptosis and with inhibition of NF-κB-dependent transcription in PC3 cells. Selective protection of normal tissue compartments by RTA 408 critically depended on tissue context and could not be replicated in vitro. Collectively, these data highlight the potential of RTA 408 as a cytoprotective agent that may be safely used in chemoradiation approaches.

Anti-cancer effects of ursane triterpenoid as a single agent and in combination with cisplatin in bladder cancer

Ursolic acid and most of its derivatives are cytotoxic to bladder cancer cells. An ursolic acid derivative, isopropyl 3β-hydroxyurs-12-en-28-oat (UA17), previously reported that it exhibited potent cytotoxicity against bladder cancer cells, NTUB1 cells. In this study, we further investigated the underlying mechanism of UA17 and evaluated its potential clinical use. UA17 may exert the onset of a p53-mediated p38 MAPK activation to up-regulate GADD153. GADD153, in turn, down-regulated Bcl-2 protein to cause mitochondrial membrane potential loss and apoptosis through intracellular ROS generation. In addition, UA17 markedly decreased the levels of cyclins (D1 and E), cyclin-dependent kinases (CDK2 and CDK4), and caused increase of p21 and p27 levels. To assess the suitability of UA17 as a chemotherapeutic agent against NTUB1 cells, its cytotoxic effects have been further evaluated in the combination with cisplatin. The addition of UA17 to cisplatin induces possibly additive cell growth inhibition which correlated to the accumulation of S phase cells and a corresponding decrease in accumulation of G1 phase cells, accompanied an increased accumulation of sub-G1 phase cells. Furthermore, UA17/cisplatin combination exhibited increase of p21, cyclin E, and p-p53 level, and decrease of p27 and cyclin D1 proteins, and slightly diminishing the level of CDK2. P-p38 up-regulation induced by UA17/cisplatin combination through generation of ROS and Bcl-2 down-regulation induced by UA17/cisplatin combination increased cell death. Finally, the antitumorigenic effects of UA17 or UA17/cisplatin combination were further supported by their inhibition on growth of bladder tumor cells in a therapeutic murine MBT-2 bladder tumor model.

Substituted 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones intercalate into DNA and cause genotoxicity through the increased generation of reactive oxygen species culminating in cell death

Naphthoquinones interact with biological systems by generating reactive oxygen species (ROS) that can damage cancer cells. The cytotoxicity and the antitumor activity of 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones (DPB1‑DPB9) were evaluated in the MCF7 human breast cancer cell line and in male Ehrlich tumor‑bearing Balb/c mice. DPB4 was the most cytotoxic derivative against MCF7 cells (EC50 15 µM) and DPB6 was the least cytotoxic one (EC50 56 µM). The 1,4‑naphthoquinone derivatives were able to cause DNA damage and promote DNA fragmentation as shown by the plasmid DNA cleavage assay (FII form). In addition, 1,4‑naphthoquinone derivatives possibly interacted with DNA as intercalating agents, which was demonstrated by the changes caused in the fluorescence of the DNA‑ethidium bromide complexes. Cell death of MCF7 cells induced by 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones was mostly due to apoptosis. The DNA fragmentation and subsequent apoptosis may be correlated to the redox potential of the 1,4‑naphthoquinone derivatives that, once present in the cell nucleus, led to the increased generation of ROS. Finally, certain 1,4‑naphthoquinone derivatives and particularly DPB4 significantly inhibited the growth of Ehrlich ascites tumors in mice (73%).