Recent advances on analytical technology of proteomics offer exciting opportunities to find novel and multiple biomarkers. Among proteomic procedures for differential analysis developed until today, two-dimensional differential gel electrophoresis (2D-DIGE) is one of the most useful techniques on analyzing the proteins containing their modified forms. Using this 2D-DIGE, we carried out a search for the disease-associated proteins linking to the potential diagnostic biomarkers for a highly malignant type in human ovarian cancer, clear cell adenocarcinoma (CCA).
In this study, we first performed a differential analysis using human ovarian cultured cell lines OVISE and OVTOKO as CCA cell lines in comparison with MCAS as a control cell line. Then the proteins characteristically expressed in CCA cell lines were identified by mass spectrometry. As a result of this analysis, some of the identified proteins were previously observed as alternative expression levels in ovarian and/or other cancers in clinical samples. In a subsequent preliminary differential study using surgical specimens from patients with CCA, it was demonstrated that some of the identified proteins were expressed differentially in actual tissues as well as in the CCA culture cells. The results from this investigation show the effectiveness of a proteomic approach to identify expressed proteins that are characteristic for particular cancers, which may eventually serve as diagnostic markers or therapeutic targets in CCA.