title: KLK6 and KLK13 predict tumor recurrence in epithelial ovarian carcinoma.
abstract: BACKGROUND
  The human kallikrein-related peptidase family consists of 15 genes. Twelve of these genes are overexpressed in ovarian cancer and may represent potential markers for diagnosis, prognosis, and/or response to treatment. The aim of this study was to determine the prognostic significance of kallikrein-related peptidase 6 (KLK6) and kallikrein-related peptidase 13 (KLK13) in epithelial ovarian cancer by quantifying gene expression levels with tumour pathology and patient survival data.
  
  
  METHODS
  Total RNA was isolated from 106 patients diagnosed with primary ovarian cancer, as well as 8 normal ovary controls. Samples were analysed by quantitative real-time PCR for KLK6 and KLK13 expression. Correlation between kallikrein gene expression and clinical characteristics was evaluated with the chi(2)-test. Survival analysis was performed using Kaplan-Meier and Cox proportional hazards regression models.
  
  
  RESULTS
  Expression levels of both KLK6 and KLK13 mRNA were significantly increased in invasive cancers relative to normal ovaries (P=0.002 and 0.039 respectively). High KLK6 and KLK13 expression was an indicator of poor prognosis, with patients having a shorter recurrence-free survival (P=0.002 and 0.027 respectively). High KLK6 expression was also significantly associated with lower overall survival (P=0.011). When subjected to multivariate analysis, patients with either high KLK6 or KLK13 were 3- and 2.2-fold, respectively, more likely to have a recurrence than patients with low kallikrein expression.
  
  
  CONCLUSIONS
  These data show increased mRNA expression of KLK6 and KLK13 in ovarian cancer compared to normal ovarian tissues. High KLK6 or KLK13 expression in primary ovarian tumours can significantly predict prognosis in terms of recurrence-free survival and overall survival. In all, this study shows KLK6 and KLK13 as potential biomarkers and may be therapeutic targets for treatment of ovarian cancer.
authors.affiliation: Division of BioMedical Sciences, Memorial University, St John's, Newfoundland, Canada.
authors.forename: N M A
authors.initials: NM
authors.lastname: White
authors.forename: M
authors.initials: M
authors.lastname: Mathews
authors.forename: G M
authors.initials: GM
authors.lastname: Yousef
authors.forename: A
authors.initials: A
authors.lastname: Prizada
authors.forename: C
authors.initials: C
authors.lastname: Popadiuk
authors.forename: J J E
authors.initials: JJ
authors.lastname: Doré
mesh_terms: D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007610:Kallikreins / Q000032:analysis / Q000235:genetics*; D009364:Neoplasm Recurrence, Local; D009375:Neoplasms, Glandular and Epithelial / Q000737:chemistry / Q000378:metabolism / Q000401:mortality*; D010051:Ovarian Neoplasms / Q000737:chemistry / Q000378:metabolism / Q000401:mortality*; D011379:Prognosis; D012333:RNA, Messenger / Q000032:analysis; D012044:Regression Analysis
chemical_list: D012333:RNA, Messenger; C470778:KLK13 protein, human; C103551:KLK6 protein, human; D007610:Kallikreins
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