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, which is a subgroup of the serine protease enzyme family. In normal human tissues, KLK5 is highly expressed in skin, mammary gland and testis. Preliminary RT-PCR analysis has indicated that KLK5 is expressed in a subset of ovarian tumours. We have thus hypothesized that KLK5 may be a new prognostic indicator in ovarian cancer. We have examined the mRNA expression of KLK5 in 142 malignant ovarian tissues. Tumours were pulverized, total RNA was extracted, and cDNA was prepared by reverse transcription. KLK5 was amplified by PCR using gene specific primers, and the identity of the PCR product was verified by sequencing. Ovarian tissues were then classified as KLK5 positive or negative, based on ethidium bromide staining of the PCR product on agarose gels. KLK5 was found to be highly expressed in 58/142 (41%) of ovarian cancer samples while its level of expression was very low in normal ovarian tissues. We found a strong positive relation between KLK5 expression and tumour grade (P = 0.006) and disease stage (P = 0.027). Univariate survival analysis revealed that patients with ovarian tumours positive for KLK5 expression 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 (grades I and II). We conclude that KLK5 expression is associated with more aggressive forms of epithelial ovarian carcinoma and has indepdent prognostic value in low grade tumours. © 2001 Cancer Research Campaign http://www.bjcancer.co

Immunofluorometric quantitation and histochemical localisation of kallikrein 6 protein in ovarian cancer tissue: a new independent unfavourable prognostic biomarker

Human kallikrein 6 protein is a newly discovered human kallikrein. We determined the amount of human kallikrein 6 in extracts of 182 ovarian tumours and correlated specific activity (ng hK6 mg−1 total protein) with clinicopathological variables documented at the time of surgical excision and with outcome (progression free survival, overall survival) monitored over a median interval of 62 months. Thirty per cent of the tumours were positive for human kallikrein 6 (>35 ng hK6 mg−1 total protein). Human kallikrein 6-specific immunohistochemical staining of four ovarian tissues that included benign, borderline and malignant lesions indicated a cytoplasmic location of human kallikrein 6 in tumour cells of epithelial origin, although the intensity of staining was variable. Tumour human kallikrein 6 (ng hK6 mg−1 total protein) was higher in late stage disease, serous histotype, residual tumour >1 cm and suboptimal debulking (>1 cm) (P<0.05). Univariate analysis revealed that patients with tumour human kallikrein 6 positive specific activity were more likely to suffer progressive disease and to die (hazard ratio 1.71 (P=0.015) and 1.88 (P=0.022), respectively). Survival curves demonstrated the same (P=0.013 and 0.019, respectively). Multivariate analysis revealed that human kallikrein 6 positivity was retained as an independent prognostic variable in several subgroups of patients, namely those with (low) grade I and II tumours (hazard ratio progression free survival 4.3 (P=0.027) and overall survival 4.1 (P=0.023)) and those with optimal debulking (hazard ratio progression free survival 3.8 (P=0.019) and overall survival 5.6 (P=0.011)). We conclude that tumour kallikrein 6 protein levels have utility as an independent adverse prognostic marker in a subgroup of ovarian cancer patients with otherwise apparently good prognosis

The RON and MET oncogenes are co-expressed in human ovarian carcinomas and cooperate in activating invasiveness

RON is a member of the receptor tyrosine kinase gene family that includes the MET oncogene, whose germline mutations have been causally related to human tumorigenesis. In vitro, RON and MET receptors cross-talk, synergize in intracellular signaling, and cooperate in inducing morphogenic responses. Here we show that the RON and MET oncogenes were expressed in 55% and 56% of human ovarian carcinomas, respectively, and were significantly coexpressed in 42% (P<0.001). In ovarian carcinoma samples and cell lines we did not find mutations in RON and MET gene kinase domain, nor coexpression of RON and MET receptor ligands (MSP and HGF, respectively). We show that motility and invasiveness of ovarian cancer cells coexpressing MET and RON receptors were elicited by HGF and, to a lesser extent, by MSP. More interestingly, invasion of both reconstituted basement membrane and collagen get was greatly enhanced by the simultaneous addition of the two ligands. These data suggest that coexpression of the MET and RON receptors confer a selective advantage to ovarian cancer cells and might promote ovarian cancer progression

Methylation of tumor suppressor gene p16 and prognosis of epithelial ovarian cancer

Objective. Methylation of p16 promoter was evaluated in ovarian cancer to determine the role of p16 methylation in ovarian cancer prognosis. Methods. Two hundred and forty-nine patients with primary epithelial ovarian cancer were selected for the study; these patients were followed for a median of 31 months. Genomic DNA extracted from fresh frozen tumor tissues were treated with sodium bisulfite and were analyzed for p16 methylation using methylation-specific PCR (MSP). Cox regression survival analysis was performed to examine the associations of p16 methylation with progression-free and overall survivals. Results. Of the 249 patients, 100 (40%) were tested positive for p16 promoter methylation. The status of p16 methylation did not change significantly with patient age, disease stage, histological grade, residual tumor size, and debulking results, although p16 methylation seemed to occur more often in patients with advanced diseases or aggressive tumors. Compared to those without p16 methylation, patients with p16 methylation had significantly higher risk for disease progression ( P = 0.01). The relative risk for progression was 1.69 (95% CI: 1.12–2.54), and the association remained statistically significant (RR = 1.54, 95% CI: 1.01–2.34) after adjusting for clinical and pathological variables. The risk for death was also higher in methylation positive patients than in methylation negative patients (RR = 1.33, 95% CI: 0.88–2.00), but the difference was not statistically significant. Conclusion. The study suggests that promoter methylation in the p16 gene is associated with ovarian cancer progression, and evaluation of p16 methylation may have values in predicting ovarian cancer prognosis