Human kallikrein gene 5 (KLK5) expression is an indicator of poor prognosis in ovarian cancer

Kallikrein gene 5 (KLK5, also known as KLK-L2), located on chromosome 19q13 .4, is one of the newly identified members of the kallikrein gene family, w hich is a subgroup of the serine protease enzyme family. In normal human ti ssues, KLK5 is highly expressed in skin. mammary gland and testis. Prelimin ary RT-PCR analysis has indicated that KLK5 is expressed in a subset of ova rian tumours. We have thus hypothesized that KLK5 may be a new prognostic i ndicator in ovarian cancer. We have examined the mRNA expression of KLK5 in 142 malignant ovarian tissues. Tumours were pulverized, total RNA was extr acted, and cDNA was prepared by reverse transcription. KLK5 was amplified b y PCR using gene specific primers, and the identity of the PCR product was verified by sequencing. Ovarian tissues were then classified as KLK5 positi ve or negative, based on ethidium bromide staining of the PCR product on ag arose gels. KLK5 was found to be highly expressed in 58/142 (41%) of ovaria n cancer samples while its level of expression was very low in normal ovari an tissues. We found a strong positive relation between KLK5 expression and tumour grade (P = 0.006) and disease stage (P = 0.027). Univariate surviva l analysis revealed that patients with ovarian tumours positive for KLK5 ex pression had an increased risk for relapse and death (P = 0.018 and 0.022, respectively). In multivariate analysis, KLK5 expression showed independent prognostic value only in the subset of tumours with lower grade disease (g rades I and II). We conclude that KLK5 expression is associated with more a ggressive forms of epithelial ovarian carcinoma and has independent prognos tic value in low grade tumours. (C) 2001 Cancer Research Campaign.