| Autor: |
Tornyi I; Department of Human Genetics, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary.; Department of Pulmonology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary.; Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary.; Biosystems Immunolab Zrt., 4025 Debrecen, Hungary., Lazar J; Biosystems Immunolab Zrt., 4025 Debrecen, Hungary.; Biosystems International Kft., 4025 Debrecen, Hungary., Pettko-Szandtner A; Proteomics Laboratory, Biological Research Center, 6726 Szeged, Hungary., Hunyadi-Gulyas E; Proteomics Laboratory, Biological Research Center, 6726 Szeged, Hungary., Takacs L; Department of Human Genetics, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary. |
| Abstrakt: |
The human proteome is more complex than the genetic code predicts it to be. Epitomics, or protein epitome profiling, is a tool for understanding sub-protein level variation. With the ultimate goal to explore C9 proteoforms and their relevance to lung cancer, here we report plasma C9 epitope-associated molecular heterogeneity in plasma samples of lung cancer patients and control subjects. We show three C9 epitopes (BSI0449, BSI0581, BSI0639) with markedly different association with lung cancer ("unaltered", "upregulated" and "downregulated"). In order to exclude confounding effects, we show first that the three epitope-defining mAbs recognize C9 in purified form and in the natural context, in the human plasma. Then, we present data demonstrating the lack of major epitope interdependence or overlap. The next experiments represent a quest toward the understanding of the molecular basis of apparent disparate association with lung cancer. Using immunochemistry, SDS PAGE and LC-MS/MS technologies, we demonstrate that epitope-specific immunoprecipitates of plasma C9 seem identical regarding peptide sequence. However, we found epitope-specific posttranslational modification and coprecipitated protein composition differences with respect to control and lung cancer plasma. Epitope profiling enabled the classification of hypothetical C9 proteoforms through differential association with lung cancer. |
