Oviductal glycoprotein (OVGP1, MUC9): a differentiation-based mucin present in serum of women with ovarian cancer.

Introduction: Epithelial ovarian carcinomas are highly lethal because most are detected at late stages. A previous immunohistochemical analysis showed that oviductal glycoprotein 1 (OVGP1), a secretory product of the oviductal epithelium under estrogen dominance, is produced predominantly by borderline and low-grade malignant epithelial ovarian tumors. In the present study, we investigated OVGP1 as a possible serum marker for the detection of ovarian cancer.

Methods: We generated a highly specific monoclonal antibody, clone 7E10, to human OVGP1. Using 7E10 and a polyclonal antibody, a sandwich enzyme-linked immunosorbent assay was developed to assay OVGP1 levels in 135 normal sera, and sera from 21 benign tumors, 12 borderline tumors, and 87 ovarian cancers (18, grade 1-2 serous; 44, grade 3 serous; 10, mucinous; 10, clear cell; and 5, endometrioid).

Results: Using a 95% confidence interval cutoff from the mean of normal postmenopausal sera, median OVGP1 levels were elevated in the sera from 75% of the women with borderline tumors and 80% of the women with mucinous, 60% with clear cell, 59% with grade 1 and 2 serous, 22% with grade 3 serous, and 0% with endometrioid carcinomas. By stage, OVGP1 levels were highest in the sera from the borderline tumors, stage I and II serous carcinomas, and mucinous carcinomas. OVGP1 levels varied independently of cancer antigen 125 (CA125).

Conclusions: Increases in OVGP1 serum levels vary with ovarian tumor histotypes and stages. Being differentiation based, OVGP1 seems to detect a different spectrum of ovarian epithelial cancers than other markers and thus should be a useful adjunct for more accurate detection, particularly of early serous ovarian cancers and mucinous carcinomas, which tend to lack increased CA125.