Objective: To investigate the expression of dipeptidyl peptidase IV (DPPIV) in patients with epithelial ovarian carcinoma (EOC) and its clinical significance.
Methods: Immunohistochemistry (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.
Results: Among 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).
Conclusion: DPPIV may be involved in the carcinogenesis of ovarian cancer, and may become a potential prognostic marker for epithelial ovarian carcinoma.