Browsing by Author "Vicente, Francisca"
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- Discovery of a Novel, Isothiazolonaphthoquinone-Based Small Molecule Activator of FOXO Nuclear-Cytoplasmic ShuttlingPublication . Cautain, Bastien; Castillo, Francisco; Musso, Loana; Ferreira, Bibiana; de Pedro, Nuria; Quesada, Lorena Rodriguez; Machado, Susana; Vicente, Francisca; Dallavalle, Sabrina; Link, WolfgangFOXO factors are tumour suppressor proteins commonly inactivated in human tumours by posttranslational modifications. Furthermore, genetic variation within the FOXO3a gene is consistently associated with human longevity. Therefore, the pharmacological activation of FOXO proteins is considered as an attractive therapeutic approach to treat cancer and age-related diseases. In order to identify agents capable of activating FOXOs, we tested a collection of small chemical compounds using image-based high content screening technology. Here, we report the discovery of LOM612 (compound 1a), a newly synthesized isothiazolonaphthoquinone as a potent FOXO relocator. Compound 1a induces nuclear translocation of a FOXO3a reporter protein as well as endogenous FOXO3a and FOXO1 in U2OS cells in a dose-dependent manner. This activity does not affect the subcellular localization of other cellular proteins including NFkB or inhibit CRM1-mediated nuclear export. Furthermore, compound 1a shows a potent antiproliferative effect in human cancer cell lines.
- High-content screening of natural products reveals novel nuclear export inhibitorsPublication . Cautain, Bastien; de Pedro, Nuria; Garzon, Virginia Murillo; de Escalona, Maria Munoz; Menendez, Victor Gonzalez; Tormo, Jose R.; Martin, Jesus; El Aouad, Noureddine; Reyes, Fernando; Asensio, Francisco; Genilloud, Olga; Vicente, Francisca; Link, WolfgangNatural products are considered an extremely valuable source for the discovery of new drugs against diverse pathologies. As yet, we have only explored a fraction of the diversity of bioactive compounds, and opportunities for discovering new natural products leading to new drugs are huge. In the present study, U2nesRELOC, a previously established cell-based imaging assay, was employed to screen a collection of extracts of microbial origin for nuclear export inhibition activity. The fluorescent signal of untreated U2nesRELOC cells localizes predominantly to the cytoplasm. Upon treatment with the nuclear export inhibitor leptomycin B, the fluorescent-tagged reporter proteins appear as speckles in the nucleus. A proprietary collection of extracts from fungi, actinomycetes, and unicellular bacteria that covers an uncommonly broad chemical space was used to interrogate this nuclear export assay system. A two-step image-based analysis allowed us to identify 12 extracts with biological activities that are not associated with previously known active metabolites. The fractionation and structural elucidation of active compounds revealed several chemical structures with nuclear export inhibition activity. Here we show that substrates of the nuclear export receptor CRM1, such as Rev, FOXO3a and NF-B, accumulate in the nucleus in the presence of the fungal metabolite MDN-0105 with an IC50 value of 3.4 mu M. Many important processes in tumor formation and progression, as well as in many viral infections, critically depend on the nucleocytoplasmic trafficking of proteins and RNA molecules. Therefore, the disruption of nuclear export is emerging as a novel therapeutic approach with enormous clinical potential. Our work highlights the potential of applying high-throughput phenotypic imaging on natural product extracts to identify novel nuclear export inhibitors.