Ovarian cancer is the most lethal gynecological malignancy, and specific biomarkers are important needed to improve diagnosis, prognosis, and to forecast and monitor treatment efficiency. There are a lot of pathological factors, including reactive oxygen species (ROS), involved in the process of cancer initiation and progression. The oxidative modification of proteins by ROS is implicated in the etiology or progression of disorders and diseases. In this study, a labeling experiment with the thiol-modifying reagent biotinylated iodoacetamide (BIAM) revealed that a variety of proteins were differentially oxidized between normal and tumor tissues of ovarian cancer patients. To identify cysteine oxidation-sensitive proteins in ovarian cancer patients, we performed comparative analysis by nano-UPLC-MSE shotgun proteomics. We found oxidation-sensitive 22 proteins from 41 peptides containing cysteine oxidation. Using Ingenuity program, these proteins identified were established with canonical network related to cytoskeletal network, cellular organization and maintenance, and metabolism. Among oxidation-sensitive proteins, the modification pattern of Collagen alpha-1(VI) chain (COL6A1) was firstly confirmed between normal and tumor tissues of patients by 2-DE western blotting. This result suggested that COL6A1 might have cysteine oxidative modification in tumor tissue of ovarian cancer patients.

ABSTRACT   INTRODUCTION   MATERIALS AND METHODS    Tissue Specimens    Two-Dimensional Gel Electrophoresis (2-DE) and WesternBlotting    Nano-UPLC MSE Shotgun Proteomics    In-gel Tryptic Digestion    Nano-UPLC-MSE Tandem Mass Spectrometry    Protein and Peptide Identification    Bioinformatics Analysis   RESULTS    Differential Oxidative Modification of Ovarian Cancer Patients    Reciprocal Networks of Proteins Containing Cysteine Oxidation    Different Modification Pattern of COL6A1   DISCUSSION   REFERENCES

• Hee-Young Yang(Department of Oral Biochemistry, Dental Science Research Institute and the BK21 Project, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757, Korea)
• Tae-Hoon Lee(Department of Oral Biochemistry, Dental Science Research Institute and the BK21 Project, Medical Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757, Korea) Corresponding author