Integral membrane proteins are generally under-represented in routine proteomic analyses, mostly because of their relatively low abundance, hydrophobicity and lack of trypsin-cleavage sites. To increase the coverage of membrane proteomes, various strategies have been developed, targeting mostly the extra-membrane segments of membrane proteins. We focused our attention to the rather overlooked hydrophobic transmembrane segments. Such peptides can be isolated after carbonate stripping and protease "shaving" of membranes isolated by simple centrifugation procedure. The treated membranes with embedded hydrophobic peptides can then be solubilized in organic solvents, re-digested with CNBr, delipidated and subjected to LC-MS/MS analysis. We modified the original "hppK" method, and applied it for the analysis of human lymphoma cells. We identified 1224 proteins of which two-thirds were IMPs with 1-16 transmembrane segments. This method allowed us to identify 13 "missing proteins" - proteins with no previous evidence on protein level. BIOLOGICAL SIGNIFICANCE: Integral membrane proteins execute numerous essential functions and represent substantial part of eukaryotic proteomes. Our knowledge of their function and expression is, however, limited. Novel approaches extending our knowledge of membrane proteome are therefore highly desired. As we demonstrate here, a non-conventional method which targets rather overlooked hydrophobic transmembrane segments of integral membrane proteins has wide potential to provide the missing information on the membrane proteome. We show that it can deliver identification and potentially also quantification of hundreds of integral membrane proteins including the so called "missing proteins".

• MeSH
• chromatografie kapalinová metody   MeSH
• hydrofobní a hydrofilní interakce MeSH
• lidé MeSH
• lymfom z plášťových buněk chemie   MeSH
• membránové proteiny analýza   MeSH
• nádorové proteiny analýza   MeSH
• peptidy analýza   MeSH
• proteom chemie   MeSH
• proteomika metody   MeSH
• tandemová hmotnostní spektrometrie metody   MeSH
• trypsin chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mantle cell lymphoma (MCL) is a chronically relapsing aggressive type of B-cell non-Hodgkin lymphoma considered incurable by currently used treatment approaches. Fludarabine is a purine analog clinically still widely used in the therapy of relapsed MCL. Molecular mechanisms of fludarabine resistance have not, however, been studied in the setting of MCL so far. We therefore derived fludarabine-resistant MCL cells (Mino/FR) and performed their detailed functional and proteomic characterization compared to the original fludarabine sensitive cells (Mino). We demonstrated that Mino/FR were highly cross-resistant to other antinucleosides (cytarabine, cladribine, gemcitabine) and to an inhibitor of Bruton tyrosine kinase (BTK) ibrutinib. Sensitivity to other types of anti-lymphoma agents was altered only mildly (methotrexate, doxorubicin, bortezomib) or remained unaffacted (cisplatin, bendamustine). The detailed proteomic analysis of Mino/FR compared to Mino cells unveiled over 300 differentially expressed proteins. Mino/FR were characterized by the marked downregulation of deoxycytidine kinase (dCK) and BTK (thus explaining the observed crossresistance to antinucleosides and ibrutinib), but also by the upregulation of several enzymes of de novo nucleotide synthesis, as well as the up-regulation of the numerous proteins of DNA repair and replication. The significant upregulation of the key antiapoptotic protein Bcl-2 in Mino/FR cells was associated with the markedly increased sensitivity of the fludarabine-resistant MCL cells to Bcl-2-specific inhibitor ABT199 compared to fludarabine-sensitive cells. Our data thus demonstrate that a detailed molecular analysis of drug-resistant tumor cells can indeed open a way to personalized therapy of resistant malignancies.

• MeSH
• antitumorózní látky farmakologie   MeSH
• chemorezistence * MeSH
• chromatografie kapalinová metody   MeSH
• izotopové značení metody   MeSH
• lidé MeSH
• lymfom z plášťových buněk farmakoterapie   metabolismus   MeSH
• nádorové biomarkery metabolismus   MeSH
• nádorové buňky kultivované MeSH
• proteomika metody   MeSH
• tandemová hmotnostní spektrometrie metody   MeSH
• vidarabin analogy a deriváty   farmakologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH