OBJECTIVETo investigate the expression of dipeptidyl peptidase IV (DPPIV) in patients with epithelial ovarian carcinoma (EOC) and its clinical significance.

METHODSImmunohistochemistry (IHC) was used to detect the expression of DPPIV protein in 378 formalin-fixed paraffin-embedded EOC tissue samples. The expression of DPPIV mRNA in 86 EOC tissue samples were examined by in situ hybridization (ISH) using specific FITC-labelled RNA probes. Forty-two samples of normal ovarian tissues were used as control. Statistical analyses were carried out by Chi-square test, Spearman rank correlation and Kaplan-Meier method.

RESULTSAmong the 378 epithelial ovarian carcinomas, 351 (92.9%) showed a positive expression of DPPIV protein, while only 25/42 (59.5%) of normal ovaries had a positive expression by semi-quantitative IHC analysis. The expression level of DPPIV protein was significantly lower in the normal ovaries than that in ovarian carcinomas (chi(2) = 18.4, P = 0.001). There was no significant correlation between the expression of DPPIV protein and age, FIGO stage and histological grade (P > 0.05). However, the expression of DPPIV protein was significantly associated with histological type (chi(2) = 28.5, P = 0.005). The patients with high level expression of DPPIV protein likely had a poor prognosis in terms of overall survival (P = 0.02). Of the 86 patients, 84 (97.7%)showed positive expression of DPPIV mRNA, also higher than that in normal ovarian tissues (P < 0.05). A statistically significant correlation between DPPIV mRNA and protein expression was observed (r(s) = 0.66, P = 0.001).

CONCLUSIONDPPIV may be involved in the carcinogenesis of ovarian cancer, and may become a potential prognostic marker for epithelial ovarian carcinoma.