Suchergebnisse

North bicyclo methanocarba thymidine (TN) nucleosides were substituted into siRNAs to investigate the effect of bicyclo[3.1.0]hexane 2′-deoxy-pseudosugars on RNA interference activity. Here we provide evidence that these modified siRNAs are compatible with the intracellular RNAi machinery. We studied the effect of the TN modification in a screen involving residue-specific changes in an siRNA targeting Renilla luciferase and we applied the most effective pattern of modification to the knockdown of murine tumor necrosis factor (TNF-α). We also showed that incorporation of TN units into siRNA duplexes increased their thermal stabilities, substantially enhanced serum stabilities, and decreased innate immunostimulation. Comparative RNAi studies involving the TN substitution and locked nucleic acids (LNAs) showed that the gene-silencing activities of TN-modified siRNAs were comparable to those obtained with the LNA modification. An advantage of the North 2′-deoxy-methanocarba modification is that it may be explored further in the future by changing the 2′-position. The results from these studies suggest that this modification might be valuable for the development of siRNAs for therapeutic applications. ; This research was supported by the European Union (MULTIFUN consortium), the Spanish Ministry of Education (BFU2007-63287, CTQ2010-20541), and the Generalitat the Catalunya (2009/SGR/208). This work was funded in part by the Center for Cancer Research, National Cancer Institute, NIH. M.T. acknowledges the JAE-Doc 2008 contract (CSIC, Spain) and the Juan de la Cierva contract (MICINN, Spain) for financial support. ; Peer reviewed

Mitochondrial metabolism and the generation of reactive oxygen species (ROS) contribute to the acquisition of DNA mutations and genomic instability in cancer. How genomic instability influences the metabolic capacity of cancer cells is nevertheless poorly understood. Here, we show that homologous recombination‐defective (HRD) cancers rely on oxidative metabolism to supply NAD+ and ATP for poly(ADP‐ribose) polymerase (PARP)‐dependent DNA repair mechanisms. Studies in breast and ovarian cancer HRD models depict a metabolic shift that includes enhanced expression of the oxidative phosphorylation (OXPHOS) pathway and its key components and a decline in the glycolytic Warburg phenotype. Hence, HRD cells are more sensitive to metformin and NAD+ concentration changes. On the other hand, shifting from an OXPHOS to a highly glycolytic metabolism interferes with the sensitivity to PARP inhibitors (PARPi) in these HRD cells. This feature is associated with a weak response to PARP inhibition in patient‐derived xenografts, emerging as a new mechanism to determine PARPi sensitivity. This study shows a mechanistic link between two major cancer hallmarks, which in turn suggests novel possibilities for specifically treating HRD cancers with OXPHOS inhibitors ; This study has been funded by the Ministerio de Ciencia, Innovación y Universidades, which is part of the Agencia Estatal de Investigación (AEI), through the project SAF2017-85869-R (cofunded by the European Regional Development Fund (ERDF), a way to build Europe) to FV and BFU2015-66030-R to JCP; by the FIS PI15/00854 and FIS PI16/01898 (Instituto Carlos III, cofunded by FEDER funds/European Regional Development Fund (ERDF), a way to build Europe) to MAP and AVillanueva and with the support of the Secretariat for Universities and Research of the Department of Business and Knowledge of the Government of Catalonia (2017SGR449) to FV. We thank the CERCA Program/Generalitat de Catalunya for their institutional support. We particularly wish to acknowledge the collaboration of ...