Expression of multiple tumour markers in serum from patients with ovarian carcinoma and healthy women

Glycoproteomic Analysis of Malignant Ovarian Cancer Ascites Fluid Identifies Unusual Glycopeptides

Ovarian cancer is a major cause of cancer mortality among women, largely due to late diagnosis of advanced metastatic disease. More extensive molecular analysis of metastatic ovarian cancer is needed to identify post-translational modifications of proteins, especially glycosylation that is particularly associated with metastatic disease to better understand the metastatic process and identify potential therapeutic targets. Glycoproteins in ascites fluid were enriched by affinity binding to lectins (ConA or WGA) and other affinity matrices. Separate glycomic, proteomic, and glycopeptide analyses were performed. Relative abundances of different N-glycan groups and proteins were identified from ascites fluids and a serum control. Levels of biomarkers CA125, MUC1, and fibronectin were also monitored in OC ascites samples by Western blot analysis. N-Glycan analysis of ascites fluids showed the presence of large, highly fucosylated and sialylated complex and hybrid glycans, some of which were not observed in normal serum. OC ascites glycoproteins, haptoglobin, fibronectin, lumican, fibulin, hemopexin, ceruloplasmin, alpha-1-antitrypsin, and alpha-1-antichymotrypsin were more abundant in OC ascites or not present in serum control samples. Further glycopeptide analysis of OC ascites identified N- and O-glycans in clusterin, hemopexin, and fibulin glycopeptides, some of which are unusual and may be important in OC metastasis.

Evaluation of two new assays for tumor-associated antigens, CASA and OSA, found in the serum of patients with epithelial ovarian carcinoma--comparison with CA125

Two new assays have been developed to measure tumor-associated antigens designated ovarian serum antigen (OSA) and cancer-associated serum antigen (CASA). Both assays are dual epitope ELISAs using the same capture monoclonal antibody (BC2); the second antibodies in the OSA and CASA assays are OM-1 and BC3, respectively. Using arbitrary cutoffs of 2.5 and 3.0 units/ml, 82 and 76% of 80 serum samples from ovarian cancer patients were positive for OSA and CASA, respectively, compared with 5 and 2.5% of samples from a control population of 40 women. A strong correlation was found between the two assays (r = 0.80, P less than 0.001). CA125 levels were obtained from 49 of the 80 samples; 82% of these samples were positive for CA125 (greater than 35 U/ml), 82% for OSA and 73% for CASA. Of the 9 samples negative for CA125, 3 were positive for OSA and 3 were positive for CASA. Serum OSA, CASA, and CA125 levels were determined in serial samples from 20 ovarian carcinoma patients throughout the course of their treatment. Clinical course was accurately reflected by CA125 levels in 85% of patients, by CASA in 65%, and by OSA in 75%. In 4 patients, a rise in CASA levels and, in 2 patients, a rise in OSA levels significantly predated rising CA125 levels to predict recurrence. Six of 7 serum samples obtained prior to positive second-look laparotomy were negative for CA125, while 4 were positive for OSA and 6 were positive for CASA. These results indicate that the OSA and CASA assays could be superior to CA125 for detection of small volume occult ovarian carcinoma.