Effects of (5z)-7-Oxozeaenol on the Oxidative Pathway of Cancer Cells

Aim: As part of an on going investigation of novel anticancer agents from natural origin, the biological and cellular effects of (5Z)-7-oxozeaenol on cancer cells were investigated. Materials and Methods: The expression of nuclear factor kappa B (NF-?B), I?B kinase (IKKa), IKKß and caspase-3 were analyzed by western blot. Reactive oxygen species (ROS) fluorescence and caspase luminescent assays were used to assess the intracellular effects in HeLa cervical and HT-29 colon cancer cell lines. The mitochondrial transmembrane potential (MTP) was analyzed by fluorescence-activated cell sorting (FACS). Results: Cells treated with (5Z)-7-oxozeaenol exhibited down-regulation of NF-?B in a dose-dependent manner. Treatment with (5Z)-7-oxozeaenol significantly enhanced the levels of ROS in HeLa and HT-29 cells. MTP was reduced in HT-29 cells. The expression of caspase-3 and -7 was induced in (5Z)-7-oxozeaenol treated HeLa cells, in comparison with those treated with paclitaxel. Conclusion: Our findings suggest that (5Z)-7-oxozeaenol is a potent inhibitor of the NF-?B pathway and potentiates the production of ROS, as well as induces caspase-3 and -7 in HeLa and HT-29 cancer cells. Thus, (5Z)-7-oxozeaenol represents a new lead compound for drug development, particularly as a new cancer chemotherapeutic agent, since programmed cell death might be mediated through the activation of a caspase-arbitrated pathway

Nanoparticle Drug-Delivery Systems for Peritoneal Cancers: A Case Study of the Design, Characterization and Development of the Expansile Nanoparticle

Nanoparticle (NP)-based drug-delivery systems are frequently employed to improve the intravenous administration of chemotherapy; however, few reports explore their application as an intraperitoneal therapy. We developed a pH-responsive expansile nanoparticle (eNP) specifically designed to leverage the intraperitoneal route of administration to treat intraperitoneal malignancies, such as mesothelioma, ovarian, and pancreatic carcinomatoses. This review describes the design, evaluation, and evolution of the eNP technology and, specifically, a Materials-Based Targeting paradigm that is unique among the many active- and passive-targeting strategies currently employed by NP-delivery systems. pH-responsive eNP swelling is responsible for the extended residence at the target tumor site as well as the subsequent improvement in tumoral drug delivery and efficacy observed with paclitaxel-loaded eNPs (PTX-eNPs) compared to the standard clinical formulation of paclitaxel, Taxol®. Superior PTX-eNP efficacy is demonstrated in two different orthotopic models of peritoneal cancer—mesothelioma and ovarian cancer; in a third model—of pancreatic cancer—PTX-eNPs demonstrated comparable efficacy to Taxol with reduced toxicity. Furthermore, the unique structural and responsive characteristics of eNPs enable them to be used in three additional treatment paradigms, including: treatment of lymphatic metastases in breast cancer; use as a highly fluorescent probe to visually guide the resection of peritoneal implants; and, in a two-step delivery paradigm for concentrating separately administered NP and drug at a target site. This case study serves as an important example of using the targeted disease-state's pathophysiology to inform the NP design as well as the method of use of the delivery system

Plasma Pharmacokinetics and Bioavailability of Verticillin A Following Different Routes of Administration in Mice Using Liquid Chromatography Tandem Mass Spectrometry

Verticillin A is a natural product isolated from fungal cultures and has displayed potent antibiotic, antiviral, nematocidal, and anticancer properties in vitro. While in vivo studies have been limited due to sparse supply, the in vivo efficacy data that does exist demonstrates potent anti-tumor activity in murine cancer models. The current study aims to investigate the pharmacokinetics and bioavailability of verticillin A in mice to provide guidance for further efficacy assessment in mouse models. A sensitive and specific liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of verticillin A in mouse plasma. Sample preparation was accomplished through protein precipitation, and chromatographic separation was achieved on an Agilent Zorbax Extend C18 column with a security guard cartridge C8 using a binary gradient with mobile phase A (water/0.1% formic acid) and B (ACN/0.1% formic acid) at a flow rate of 400 µl/min. Elution of verticillin A and internal standard, hesperetin, occurred at 4.87 and 2.06 min, respectively. The total chromatographic run time was 8 min, and the assay was linear in the concentration range of 1–1000 nM. The within- and between day precisions and accuracy were in the range of 2.58–8.71 and 90–105%, respectively. The assay was applied to determine plasma drug concentration in a mouse pharmacokinetic study. It was found that intraperitoneal dosing of 3 mg/kg resulted in high systemic exposure and achieved Cmax of 110 nM with plasma concentrations sustained above 10 nM for the 24-h duration of the study. Intravenous and oral dosing achieved observed Cmax of 73 nM and 9 nM, respectively. Oral dosing resulted in an approximate 9% bioavailability. Comparing with previously published in vitro studies that demonstrated verticillin A is active in the 20 nM to 130 nM range, the pharmacokinetic data demonstrate similar levels are achieved in mouse plasma via intravenous or intraperitoneal dosing routes

Effects of (5z)-7-Oxozeaenol on MDA-MB-231 Breast Cancer Cells

Aim: (5Z)-7-Oxozeaenol was studied to reveal the path through which it exerts its effects on triple-negative MDA-MB-231 breast cancer cells. Materials and Methods: The apoptotic effect of (5Z)-7-oxozeaenol on MDA-MB-231 cancer cells was analyzed by cell flow cytometry. The effects of (5Z)-7-oxozeaenol on the expression of the nuclear factor kappa B (NF-?B) p65, p50, I?B kinase (IKKa), IKKß and caspase-7 were analyzed by western blot. The expression of intracellular reactive oxygen species (ROS) and effects on cell adhesion were also assessed. Cell viability was determined using the 3[4,5-dimethylthiazol-2-yl-]2,5-diphenyl tetrazolium bromide (MTT) assay. Results: (5Z)-7-Oxozeaenol down-regulated NF-?B in a dose-dependent manner. Intracellular levels of ROS increased in a dose-dependent manner when treated with (5Z)-7-oxozeaenol and potentiated in the presence of H2O2, when compared to paclitaxel which was used as positive control. Treatment with (5Z)-7-oxozeaenol resulted in G1-phase arrest of treated cells and inhibition of cell proliferation. Cell adhesion was notably affected in treated cells. (5Z)-7-Oxozeaenol also significantly enhanced apoptosis of treated cells, through the activation of caspase-7. Conclusion: Our findings suggest that (5Z)-7-oxozeaenol is a potent up-stream inhibitor of the NF-?B pathway, enhances the sensitivity of treated cells to apoptosis induced by ROS, and affects cell adhesion of MDA-MB-231 breast cancer cells. Thus, (5Z)-7-oxozeaenol is a potential new lead for breast cancer drug development since it might, in combination therapy, enhance the efficacy of current treatments and reduce resistance to chemotherapy of triple negative breast cancer

Romidepsin (Istodax, NSC 630176, FR901228, FK228, Depsipeptide): A Natural Product Recently Approved for Cutaneous T-Cell Lymphoma

Romidepsin (Istodax), a selective inhibitor of histone deacetylases (HDACs), was approved for the treatment of cutaneous T-cell lymphoma in November 2009 by the US Food and Drug Administration. This unique natural product was discovered from cultures of Chromobacterium violaceum, a Gram-negative bacterium isolated from a Japanese soil sample. This bicyclic compound acts as a prodrug, its disulfide bridge being reduced by glutathione on uptake into the cell, allowing the free thiol groups to interact with Zn ions in the active site of class I and II HDAC enzymes. Due to the synthetic complexity of the compound, as well as the low yield from the producing organism, analogs are sought to create synthetically accessible alternatives. As a T-cell lymphoma drug, romidepsin offers a valuable new treatment for diseases with few effective therapies

Verticillin A Inhibits Leiomyosarcoma and Malignant Peripheral Nerve Sheath Tumor Growth Via Induction of Apoptosis

Objective: The heterogeneity of soft tissue sarcoma (STS) represents a major challenge for the development of effective therapeutics. Comprised of over 50 different histology subtypes of various etiologies, STS subsets are further characterized as either karyotypically simple or complex. Due to the number of genetic anomalies associated with genetically complex STS, development of therapies demonstrating potency against this STS cluster is especially challenging and yet greatly needed. Verticillin A is a small molecule natural product with demonstrated anticancer activity; however, the efficacy of this agent has never been evaluated in STS. Therefore, the goal of this study was to explore verticillin A as a potential STS therapeutic.Methods: We performed survival (MTS) and clonogenic analyses to measure the impact of this agent on the viability and colony formation capability of karyotypically complex STS cell lines: malignant peripheral nerve sheath tumor (MPNST) and leiomyosarcoma (LMS). The in vitro effects of verticillin A on apoptosis were investigated through annexin V/PI flow cytometry analysis and by measuring fluorescently-labeled cleaved caspase 3/7 activity. The impact on cell cycle progression was assessed via cytometric measurement of propidium iodide intercalation. In vivo studies were performed using MPNST xenograft models. Tumors were processed and analyzed using immunohistochemistry (IHC) for verticillin A effects on growth (Ki67) and apoptosis (cleaved caspase 3).Results: Treatment with verticillin A resulted in decreased STS growth and an increase in apoptotic levels after 24 h. 100 nM verticillin A induced significant cellular growth abrogation after 24 h (96.7, 88.7, 72.7, 57, and 39.7% reduction in LMS1, S462, ST88, SKLMS1, and MPNST724, respectively). We observed no arrest in cell cycle, elevated annexin, and a nearly two-fold increase in cleaved caspase 3/7 activity in all MPNST and LMS cell lines. Control normal human Schwann (HSC) and aortic smooth muscle (HASMC) cells displayed higher tolerance to verticillin A treatment compared to sarcoma cell lines, although toxicity was seen in HSC at the highest treatment dose. In vivo studies mirrored the in vitro results: by day 11, tumor size was significantly reduced in MPNST724 xenograft models with treatment of 0.25 and 0.5 mg/kg verticillin A. Additionally, IHC assessment of tumors demonstrated increased cleaved caspase 3 and decreased proliferation (Ki67) following treatment with verticillin A.Conclusion: Advancement in the treatment of karyotypically complex STS is confounded by the high level of genetic abnormalities found in these diseases. Consequently, the identification and investigation of novel therapies is greatly needed. Our data suggest that verticillin A selectively inhibits MPNST and LMS growth via induction of apoptosis while exhibiting minimal to moderate effects on normal cells, pointing to verticillin A as a potential treatment for MPNST and LMS, after additional preclinical validation

Revisiting the Enniatins: A Review of Their Isolation, Biosynthesis, Structure Determination and Biological Activities

Enniatins are cyclohexadepsipeptides isolated largely from Fusariumspecies of fungi, although they have been isolated from other genera, such as Verticillium and Halosarpheia. They were first described over 60 years ago, and their range of biological activities, including antiinsectan, antifungal, antibiotic and cytotoxic, drives contemporary interest. To date, 29 enniatins have been isolated and characterized, either as a single compound or mixtures of inseparable homologs. Structurally, these depsipeptides are biosynthesized by a multifunctional enzyme, termed enniatin synthetase, and are composed of six residues that alternate between N-methyl amino acids and hydroxy acids. Their structure elucidation can be challenging, particularly for enniatins isolated as inseparable homologs; however, several strategies and tools have been utilized to solve these problems. Currently, there is one drug that has been developed from a mixture of enniatins, fusafungine, which is used as a topical treatment of upper respiratory tract infections by oral and/or nasal inhalation. Given the range of biological activities observed for this class of compounds, research on enniatins will likely continue. This review strives to digest the past studies, as well as, describe tools and techniques that can be utilized to overcome the challenges associated with the structure elucidation of mixtures of enniatin homologs

Epigenetic Manipulation of a Filamentous Fungus by the Proteasome-Inhibitor Bortezomib Induces the Production of an Additional Secondary Metabolite

The use of epigenetic modifiers, such as histone deacetylase inhibitors and DNA methyltransferase inhibitors, has been explored increasingly as a technique to induce the production of additional microbial secondary metabolites. The application of such molecules to microbial cultures has been shown to upregulate otherwise suppressed genes, and in several cases has led to the production of new molecular structures. In this study, the proteasome inhibitor bortezomib was used to induce the production of an additional metabolite from a filamentous fungus (Pleosporales). The induced metabolite was previously isolated from a plant, but the configuration was not assigned until now; in addition, an analogue was isolated from a degraded sample, yielding a new compound. Proteasome inhibitors have not previously been used in this application and offer an additional tool for microbial genome mining

Contrasting Roles of H3K4me3 and H3K9me3 in Regulation of Apoptosis and Gemcitabine Resistance in Human Pancreatic Cancer Cells

Background: Pancreas ductal adenocarcinoma (PDAC) has the most dismal prognosis among all human cancers since it is highly resistant to chemotherapy, radiotherapy and immunotherapy. The anticipated consequence of all therapies is induction of tumor apoptosis. The highly resistance nature of PDACs to all therapies suggests that the intrinsic tumor cell factors, likely the deregulated apoptosis pathway, are key mechanisms underlying PDAC non-response to these therapies, rather than the therapeutic agents themselves. The aim of this study is to test the hypothesis that epigenetic dysregulation of apoptosis mediators underlies PDAC resistance to gemcitabine, the standard chemotherapy for human PDAC.Methods: PDAC cells were analyzed for apoptosis sensitivity in the presence of a selective epigenetic inhibitor. The epigenetic regulation of apoptosis regulators was determined by Western Blotting and quantitative PCR. The specific epigenetic modification of apoptosis regulator promoter chromatin was determined by chromatin immunoprecipitation in PDAC cells.Results: Inhibition of histone methyltransferase (HMTase) by a selective HMTase inhibitor, verticillin A, significantly increased human PDAC cell sensitivity to gemcitabine-induced growth suppression. Verticillin A treatment decreased FLIP, Mcl-1, Bcl-x and increased Bak, Bax and Bim protein level in the tumor cells, resulting in activation of caspases, elevated cytochrome C release and increased apoptosis as determined by upregulated PARP cleavage in tumor cells. Analysis of human PDAC specimens indicated that the expression levels of anti-apoptotic mediators Bcl-x, Mcl-1, and FLIP were significantly higher, whereas the expression levels of pro-apoptotic mediators Bim, Bak and Bax were dramatically lower in human PDAC tissues as compared to normal pancreas. Verticillin A downregulated H3K4me3 levels at the BCL2L1, CFLAR and MCL-1 promoter to decrease Bcl-x, FLIP and Mcl-1 expression level, and inhibited H3K9me3 levels at the BAK1, BAXand BCL2L11 promoter to upregulate Bak, Bax and Bim expression level.Conclusion: We determined that PDAC cells use H3K4me3 to activate Bcl-x, FLIP and Mcl-1, and H3K9me3 to silence Bak, Bax and Bim to acquire an apoptosis-resistant phenotype. Therefore, selective inhibition of H3K4me3 and H3K9me3 is potentially an effective approach to overcome PDAC cells resistance to gemcitabine

The MLL1-H3K4me3 Axis-Mediated PD-L1 Expression and Pancreatic Cancer Immune Evasion

Background: Pancreatic cancer is one of the cancers where anti-PD-L1/PD-1 immunotherapy has been unsuccessful. What confers pancreatic cancer resistance to checkpoint immunotherapy is unknown. The aim of this study is to elucidate the underlying mechanism of PD-L1 expression regulation in the context of pancreatic cancer immune evasion.Methods: Pancreatic cancer mouse models and human specimens were used to determine PD-L1 and PD-1 expression and cancer immune evasion. Histone methyltransferase inhibitors, RNAi, and overexpression were used to elucidate the underlying molecular mechanism of PD-L1 expression regulation. All statistical tests were two-sided.Results: PD-L1 is expressed in 60% to 90% of tumor cells in human pancreatic carcinomas and in nine of 10 human pancreatic cancer cell lines. PD-1 is expressed in 51.2% to 52.1% of pancreatic tumor–infiltrating cytotoxic T lymphocytes (CTLs). Tumors grow statistically significantly faster in FasL-deficient mice than in wild-type mice (P = .03–.001) and when CTLs are neutralized (P = .03–Conclusions: The Fas-FasL/CTLs and the MLL1-H3K4me3-PD-L1 axis play contrasting roles in pancreatic cancer immune surveillance and evasion. Targeting the MLL1-H3K4me3 axis is an effective approach to enhance the efficacy of checkpoint immunotherapy against pancreatic cancer