Human kallikrein 8 (hK8/TADG-14) expression is associated with an early clinical stage and favorable prognosis in ovarian cancer

The purpose of this study was to examine human kallikrein 8 (hK8/TADG-14) expression in epithelial ovarian tumors and to investigate the association of hK8 expression levels with patient survival. Human kallikrein 8 protein (hK8) expression was examined by immunohistochemistry in 74 ovarian adenocarcinomas and 6 normal ovaries. Results of immunostaining were correlated with clinicopathological variables and overall survival of the patients. Human kallikrein 8 gene (KLK8) mRNA expression was examined by semi-quantitative PCR in 35 ovarian tumors and 7 normal ovaries. Expression of hK8 was not detected on the surface epithelium of normal ovaries. In contrast, hK8 expression was detected in 51.4% (38/74) of carcinomas with a significantly higher detection rate of hK8 expression being observed in early stage disease compared to advanced stage disease (p=0.0192). Data analysis using the log-rank test showed hK8 expression correlated significantly with favorable patient survival (p=0.0328). Younger age (p=0.0008), early clinical stage (p<0.0001), and low histological grades of the tumors (p=0.0018) were also associated significantly with a favorable prognosis. In a multivariate model, age (p=0.0186) and clinical stage (p<0.0001) remained associated significantly with overall survival, whereas hK8 expression and histological grade lost their significance. There was significant relationship between the hK8 expression status and KLK8 mRNA expression levels (p=0.0304). Expression of hK8 is increased during the development of ovarian cancer and down-regulated during ovarian cancer progression. Expression of hK8 is a favorable prognostic marker in patients with ovarian cancer.