Jadomycins are natural products that kill drug-sensitive and multidrug-resistant (MDR) breast cancer cells. To date, the cytotoxic activity of jadomycins has never been tested in MDR breast cancer cells that are also triple negative. Additionally, there is only a rudimentary understanding of how jadomycins cause cancer cell death, which includes the induction of intracellular reactive oxygen species (ROS). We first created a paclitaxel-resistant, triple-negative breast cancer cell line [paclitaxel-resistant MDA-MB-231 breast cancer cells (231-TXL)] from drug-sensitive control MDA-MB-231 cells (231-CON). Using thiazolyl blue methyltetrazolium bromide cell viability-measuring assays, jadomycins B, S, and F were found to be equipotent in drug-sensitive 231-CON and MDR 231-TXL cells; and using ROS-detecting assays, these jadomycins were determined to increase ROS activity in both cell lines by up to 7.3-fold. Jadomycins caused DNA double-strand breaks in 231-CON and 231-TXL cells as measured by H2AX Western blotting. Coincubation with the antioxidant-acetyl cysteine or pro-oxidant auranofin did not affect jadomycin-mediated DNA damage. Jadomycins induced apoptosis in 231-CON and 231-TXL cells as measured by annexin V affinity assays, a process that was retained when ROS were inhibited. This indicated that jadomycins are capable of inducing MDA-MB-231 apoptotic cell death independently of ROS activity. Using quantitative polymerase chain reaction, Western blotting, and direct topoisomerase inhibition assays, it was determined that jadomycins inhibit type II topoisomerases and that jadomycins B and F selectively poison topoisomerase II We therefore propose novel mechanisms through which jadomycins induce breast cancer cell death independently of ROS activity, through inhibition or poisoning of type II topoisomerases and the induction of DNA damage and apoptosis.

/npsi/ctrl?action=rtdoc&an=21275442&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21275442&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Jadomycins are natural products biosynthesized by the bacteria Streptomyces venezuelae which kill drug-sensitive and multidrug-resistant breast cancer cells in culture. Currently, the mechanisms of jadomycin cytotoxicity are poorly understood; however, reactive oxygen species (ROS)–induced DNA cleavage is suggested based on bacterial plasmid DNA cleavage studies. The objective of this study was to determine if and how ROS contribute to jadomycin cytotoxicity in drug-sensitive MCF7 (MCF7-CON) and taxol-resistant MCF7 (MCF7-TXL) breast cancer cells. As determined using an intracellular, fluorescent, ROS-detecting probe, jadomycins B, S, SPhG, and F dose dependently increased intracellular ROS activity 2.5- to 5.9-fold. Cotreatment with the antioxidant N-acetyl cysteine lowered ROS concentrations to below baseline levels and decreased the corresponding cytotoxic potency of the four jadomycins 1.9- to 3.3-fold, confirming a ROS-mediated mechanism. Addition of CuSO4 enhanced, whereas addition of the Cu(II)-chelator d-penicillamine reduced, the ROS generation and cytotoxicity of each jadomycin. Specific inhibitors of the antioxidant enzymes, superoxide dismutase 1, glutathione S-transferase, and thioredoxin reductase, but not catalase, enhanced jadomycin-mediated ROS generation and anticancer activity. In conclusion, the results indicate that jadomycin cytotoxicity involves the generation of cytosolic superoxide via a Cu(II)-jadomycin reaction, a mechanism common to all jadomycins tested and observed in MCF7-CON and drug-resistant MCF7-TXL cells. The superoxide dismutase 1, glutathione, and peroxiredoxin/thioredoxin cellular antioxidant enzyme pathways scavenged intracellular ROS generated by jadomycin treatment. Blocking these antioxidant pathways could serve as a strategy to enhance jadomycin cytotoxic potency in drug-sensitive and multidrug-resistant breast cancers.

/npsi/ctrl?action=rtdoc&an=21277038&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21277038&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

/npsi/ctrl?action=rtdoc&an=21275909&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21275909&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

We report the production, isolation, and characterization of jadomycins with seven-, nine-, and ten-membered E-rings, all of which are unique natural product ring scaffolds. This significantly expands the scope of a non-enzymatic biosynthetic step in jadomycin biosynthesis in order to produce novel natural products.

The jadomycins are a family of secondary metabolites produced by S. venezuelae ISP5230. Specific jadomycins have been shown to possess a variety of anticancer, antifungal, and antibacterial properties, with different molecular mechanisms of action. Herein we demonstrate qualitative and quantitative direct binding between the validated anticancer target human topoisomerase IIβ and jadomycin DS using WaterLOGSY NMR spectroscopy. Additionally, we report for the first time, that jadomycin DS also binds a variety of other proteins, likely in a non-specific manner. Such interactions may rationalize the potential polypharmacology of jadomycin DS.

Okadaic acid (OA) and its analogs dinophysistoxins-1 (DTX1) and -2 (DTX2) are lipophilic polyethers produced by marine dinoflagellates. These toxins accumulate in shellfish and cause diarrhetic shellfish poisoning (DSP) in humans. Regulatory testing of shellfish is essential to safeguard public health and for international trade. Certified reference materials (CRMs) play a key role in analytical monitoring programs. This paper presents an overview of the interdisciplinary work that went into the planning, production, and certification of calibration-solution CRMs for OA, DTX1, and DTX2. OA and DTX1 were isolated from large-scale algal cultures and DTX2 from naturally contaminated mussels. Toxins were isolated by a combination of extraction and chromatographic steps with processes adapted to suit the source and concentration of each toxin. New 19-epi-DSP toxin analogs were identified as minor impurities. Once OA, DTX1, and DTX2 were established to be of suitable purity, solutions were prepared and dispensed into flame-sealed glass ampoules. Certification measurements were carried out using quantitative NMR spectroscopy and LC-tandem MS. Traceability of measurements was established through certified external standards of established purity. Uncertainties were assigned following standards and guidelines from the International Organization for Standardization, with components from the measurement, stability, and homogeneity studies being propagated into final combined uncertainties.