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Campos-Olivas R.,Spectroscopy and NMR Unit
Biomolecular NMR assignments | Year: 2011

The Src tyrosine kinase is the paradigm of an oncogenic kinase, and of regulation by intramolecular inhibitory interactions, as well as an important anticancer target due to its roles in cell proliferation and metastasis. The assignment of backbone (1)H(N), (13)C(α), (13)CO, and (15)N, and sidechain (13)C(β) resonances of the catalytic domain of Src (283 residues) in complex with the anticancer drug Imatinib is reported here. Consistent with previous X-ray studies of the same complex, most signals from the activation loop are not detected, indicating that, even in the presence of the drug, it probably adopts highly heterogeneous conformations in intermediate exchange. For the rest of the polypeptide backbone, assignments have been completed for ~88% of residues, with only a few solvent-exposed amides remaining unassigned.

Garcia-Alvarez I.,Institute Quimica Organica General | Garrido L.,CSIC - Institute of Polymer Science and Technology | Romero-Ramirez L.,Instituto Cajal Of Neurobiologia | Nieto-Sampedro M.,Instituto Cajal Of Neurobiologia | And 2 more authors.
PLoS ONE | Year: 2013

The effect of the treatment with glycolipid derivatives on the metabolic profile of intact glioma cells and tumor tissues, investigated using proton high resolution magic angle spinning (1H HR-MAS) nuclear magnetic resonance (NMR) spectroscopy, is reported here. Two compounds were used, a glycoside and its thioglycoside analogue, both showing anti-proliferative activity on glioma C6 cell cultures; however, only the thioglycoside exhibited antitumor activity in vivo. At the drug concentrations showing anti-proliferative activity in cell culture (20 and 40 μM), significant increases in choline containing metabolites were observed in the 1H NMR spectra of the same intact cells. In vivo experiments in nude mice bearing tumors derived from implanted C6 glioma cells, showed that reduction of tumor volume was associated with significant changes in the metabolic profile of the same intact tumor tissues; and were similar to those observed in cell culture. Specifically, the activity of the compounds is mainly associated with an increase in choline and phosphocholine, in both the cell cultures and tumoral tissues. Taurine, a metabolite that has been considered a biomarker of apoptosis, correlated with the reduction of tumor volume. Thus, the results indicate that the mode of action of the glycoside involves, at least in part, alteration of phospholipid metabolism, resulting in cell death. © 2013 García-Álvarez et al.

Martin-Pintado N.,CSIC - Institute of Physical Chemistry "Rocasolano" | Yahyaee-Anzahaee M.,McGill University | Campos-Olivas R.,Spectroscopy and NMR Unit | Noronha A.M.,McGill University | And 4 more authors.
Nucleic Acids Research | Year: 2012

We report here the first structure of double helical arabino nucleic acid (ANA), the C2'-stereoisomer of RNA, and the 2'-fluoro-ANA analogue (2'F-ANA). A chimeric dodecamer based on the Dickerson sequence, containing a contiguous central segment of arabino nucleotides, flanked by two 2'-deoxy- 2'F-ANA wings was studied. Our data show that this chimeric oligonucleotide can adopt two different structures of comparable thermal stabilities. One structure is a monomeric hairpin in which the stem is formed by base paired 2'F-ANA nucleotides and the loop by unpaired ANA nucleotides. The second structure is a bimolecular duplex, with all the nucleotides (2'F-ANA and ANA) forming Watson-Crick base pairs. The duplex structure is canonical B-form, with all arabinoses adopting a pure C2'-endo conformation. In the ANA:ANA segment, steric interactions involving the 2'-OH substituent provoke slight changes in the glycosidic angles and, therefore, in the ANA:ANA base pair geometry. These distortions are not present in the 2'F-ANA:2'F-ANA regions of the duplex, where the -OH substituent is replaced by a smaller fluorine atom. 2'F-ANA nucleotides adopt the C2'-endo sugar pucker and fit very well into the geometry of B-form duplex, allowing for favourable 2'F⋯⋯⋯H8 interactions. This interaction shares many features of pseudo-hydrogen bonds previously observed in 2'F-ANA:RNA hybrids and in single 2'F-ANA nucleotides. © 2012 The Author(s).

Carranza G.,University of Cantabria | Castano R.,University of Cantabria | Fanarraga M.L.,University of Cantabria | Villegas J.C.,University of Cantabria | And 10 more authors.
Cellular and Molecular Life Sciences | Year: 2013

Tubulin cofactors (TBCs) participate in the folding, dimerization, and dissociation pathways of the tubulin dimer. Among them, TBCB and TBCE are two CAP-Gly domain-containing proteins that together efficiently interact with and dissociate the tubulin dimer. In the study reported here we showed that TBCB localizes at spindle and midzone microtubules during mitosis. Furthermore, the motif DEI/M-COO- present in TBCB, which is similar to the EEY/F-COO- element characteristic of EB proteins, CLIP-170, and α-tubulin, is required for TBCE-TBCB heterodimer formation and thus for tubulin dimer dissociation. This motif is responsible for TBCB autoinhibition, and our analysis suggests that TBCB is a monomer in solution. Mutants of TBCB lacking this motif are derepressed and induce microtubule depolymerization through an interaction with EB1 associated with microtubule tips. TBCB is also able to bind to the chaperonin complex CCT containing α-tubulin, suggesting that it could escort tubulin to facilitate its folding and dimerization, recycling or degradation. © 2012 Springer Basel AG.

Sancho P.,Queen Mary, University of London | Sancho P.,Stem Cells and Cancer Group | Burgos-Ramos E.,Stem Cells and Cancer Group | Tavera A.,Stem Cells and Cancer Group | And 12 more authors.
Cell Metabolism | Year: 2015

The anti-diabetic drug metformin targets pancreatic cancer stem cells (CSCs), but not their differentiated progenies (non-CSCs), which may be related to distinct metabolic phenotypes. Here we conclusively demonstrate that while non-CSCs were highly glycolytic, CSCs were dependent on oxidative metabolism (OXPHOS) with very limited metabolic plasticity. Thus, mitochondrial inhibition, e.g., by metformin, translated into energy crisis and apoptosis. However, resistant CSC clones eventually emerged during treatment with metformin due to their intermediate glycolytic/respiratory phenotype. Mechanistically, suppression of MYC and subsequent increase of PGC-1α were identified as key determinants for the OXPHOS dependency of CSCs, which was abolished in resistant CSC clones. Intriguingly, no resistance was observed for the mitochondrial ROS inducer menadione and resistance could also be prevented/reversed for metformin by genetic/pharmacological inhibition of MYC. Thus, the specific metabolic features of pancreatic CSCs are amendable to therapeutic intervention and could provide the basis for developing more effective therapies to combat this lethal cancer. © 2015 Elsevier Inc.

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