In) were scanned with excitation/emission wavelengths of 532/560 nm according to the user’s manual. Proteins in chemosensitive ascites samples were compared with those in chemoresistant ones. Increases or decreases of protein abundance of more than 1.5-fold (t-test andBiomarkers for Chemoresistant JI 101 ovarian CancerANOVA, P,0.01) were considered significant changes. The corresponding protein spots were selected in the stained preparative gel for spot picking.Results Clinical Patient InformationNineteen ascites samples of serous EOC patients were analyzed using 2D-DIGE to screen potential biomarkers associated with differential responses to chemotherapy. Samples from a separate cohort of 28 patients with serous EOC were used for validation of the 2D-DIGE results by ELISA. All patients had received satisfactory cytoreductive surgery. There were no significant differences in age at diagnosis, tumor differentiation and International Federation of Gynecology and Obstetrics (FIGO) staging between the patients in the chemosensitive and chemoresistant groups. Demographic and clinical features of the cases are shown in Table 1. In addition, survival rates of the 28 patients tested by ELISA were compared according to their different responses to chemotherapy. By March 2012, four of the nine patients (44.4 ) in the chemoresistant group and three of nineteen patients (15.8 ) had died in the chemosensitivity group. The median survival time of the nine chemoresistant ovarian cancer patients in our study was 18.9 months. However, a longer period of follow-up was needed to determine an accurate median survival of chemosensitive patients, which was more than 18.9 months. Based on the observation period in this study, the difference in survival between the two groups as observed using Kaplan eier estimates was significant (P = 0.007), favoring those with better responses to chemotherapy (Fig. 1531364 1).Protein Spot HandlingThe selected protein spots in the preparative gels were automatically picked and handled in an Ettan Spot Handling Workstation (GE Healthcare). The selected protein spots were washed with 15 mM ammonium bicarbonate and 50 methanol and then digested in 0.02 mg/mL sequencing grade trypsin solution (Promega, Madison, WI, USA) at 37uC for 2 h. The tryptic peptides were extracted with 50 (v/v) acetonitrile (ACN) and 0.5 (v/v) trifluoroacetic acid (TFA), dissolved in 5 mg/mL R-cyano-4-hydroxycinnamic acid (Amersham Bioscience) in 50 (v/v) ACN and 0.1 (v/v) TFA and then spotted on the MS sample plate.Matrix-assisted Laser Desorption/ionization Time-of-flight Mass Spectrometry (MALDI-TOF/TOF MS) AnalysisProtein identification was performed with the ABI 4800 Proteomics MALDI-TOF/TOF Analyzer (Applied Biosystems, Foster City, CA, USA) in positive ion reflector mode. Monoisotopic peak masses were acquired in a range of 900?,000 Da with a signal-to-noise ratio (S/N) .200. Trypsin autolytic peptides of masses 842.5 and 2211.1 were used as internal standards. Five of the most intense ion signals were automatically selected as precursors for MS/MS acquisition, excluding the trypsin autolysis peaks and matrix ion signals. The peptide mass fingerprint (PMF) combined MS/MS spectra were searched against the NCBInr database using GPS ExplorerTM software (Version 3.6, Applied Biosystems) and MASCOT version 2.1 (Matrix Science). The search parameters were set as follows: Homo sapiens, trypsin cleavage (one missed cleavage allowed), carbamidomethylation as fixed m.
