Kallikrein 4 expression is up-regulated in epithelial ovarian carcinoma cells in effusions

We immunohistochemically analyzed kallikrein 4 protein (hK4) expression in effusions and solid tumors of patients with epithelial ovarian carcinoma (181 malignant effusions) or epithelial ovarian carcinoma (n = 103). Expression of hK4 also was studied it? 32 effusions using immunoblotting. Carcinoma cells expressed hK4 in 144 (79.6%) of 181 effusions and 85 (82.5%) of 103 solid tumors. Expression was seen in 51 % or more of tumor cells in 70 effusions but often was limited to 5% or fewer cells in solid tumors (P = .009, primary tumors vs effusions; P = .002, metastases vs effusions). Immunoblotting showed hK4 expression in 31 of 32 specimens. Stromal cell hK4 expression, seen in 48 (46.6%) of 103 lesions, was significantly higher in primary tumors than metastases (26143 vs 22160, P = .019). hK4 expression in tumor cells was significantly lower in International Federation of Gynecology and Obstetrics stage IV than stage III tumors (P = .004, all lesions; P = .012, primary tumors). hK4 expression in carcinoma cells was associated with longer overall survival (not significant; P = .14, peritoneal effusions). hK4 is expressed widely in ovarian carcinoma; levels in carcinoma cells are highest in effusions, which might be related to loss of stromal contribution and/or altered microenviromnent. hK4 expression in carcinoma cells of effusions or solid tumors does not predict survival.