Overexpression of kallikrein 10 (hK10) in uterine serous papillary carcinomas

Objective Kallikrein 10 is a secreted serine protease recently implicated in the growth and invasion of several human tumors. The goal of this study was to investigate the expression and secretion levels in vitro and in vivo of kallikrein 10 in uterine serous papillary carcinoma, a highly aggressive variant of endometrial tumor. Study design Human kallikrein 10 gene expression levels were evaluated in 11 snap-frozen uterine serous papillary carcinoma biopsies and 6 normal endometrial cell biopsies by real-time polymerase chain reaction. Secretion of kallikrein 10 protein by 10 primary tumor cultures including 3 uterine serous papillary carcinomas, 2 endometrioid carcinomas, and 5 ovarian serous papillary tumors was measured using a sensitive ELISA. Finally, kallikrein 10 concentration in 75 serum and plasma samples from 22 healthy women, 20 women with benign diseases, 21 women with endometrioid carcinomas, and 12 uterine serous papillary carcinoma patients was studied. Results Kallikrein 10 gene expression levels were significantly higher in uterine serous papillary carcinoma when compared with normal endometrial cell biopsies (mean copy number by real time polymerase chain reaction = 743 versus 1.4; uterine serous papillary carcinoma versus endometrioid carcinoma: P< .02). In vitro kallikrein 10 secretion was detected in all primary uterine serous papillary carcinoma cell lines tested (mean = 2.7 μg/L), and the secretion levels were not significantly different to those found in primary ovarian serous papillary tumor cultures (mean 4.2 μg/L). In contrast, no kallikrein 10 secretion was detectable in primary endometrioid carcinomas. Kallikrein 10 serum and plasma concentrations (μg/L; mean ± SEM) among normal healthy females (0.6 ± 0.04), patients with benign diseases (0.6 ± 0.06), and patients with endometrioid carcinomas (0.7 ± 0.06) were not significantly different. In contrast, serum and plasma kallikrein 10 values in uterine serous papillary carcinoma patients (1.2 ± 0.1) were significantly higher than those in the non-cancer group (P = .002), benign group (P = .002), and endometrioid carcinoma patients (P = .005). Conclusion Kallikrein 10 is highly expressed in uterine serous papillary carcinoma, and it is released in the plasma and serum of uterine serous papillary carcinoma patients. Kallikrein 10 may represent a novel biomarker for uterine serous papillary carcinoma.