title: Copy number and expression alterations of miRNAs in the ovarian cancer cell line OVCAR-3: impact on kallikrein 6 protein expression.
abstract: BACKGROUND
  Kallikrein-related peptidase 6 (KLK6), a member of the serine protease family of kallikrein (KLK) genes, is dysregulated in ovarian carcinomas (OCa) and its overexpression is associated with poor prognosis. Regulation of its expression is poorly understood and is likely to be influenced by multiple mechanisms. The KLK locus is subject to copy number changes and heterogeneity in serous OCas. These copy number imbalances generally correlate with KLK6 protein expression; however, this is not always the case. In this study we explored the role of miRNAs in the posttranscriptional control of KLK6 expression and the contributions of copy numbers, not only of the KLK locus, but also of the miRNAs predicted to regulate it.
  
  
  RESULTS
  By miRNA profiling of the KLK6-overexpressing OCa cell line, OVCAR-3, we identified overexpressed and underexpressed miRNAs. Publically available miRNA databases identified the human miRNA lethal 7 (hsa-let-7) family members as putative regulating miRNAs, from which hsa-let-7a was chosen for functional analysis. The transient transfection of hsa-let-7a to OVCAR-3 resulted in a decrease of KLK6 secreted protein. Moreover, such transfection was also able to weakly affect the expression of another member of the KLK gene family, KLK10 (kallikrein-related peptidase 10). Cytogenomic analysis, including array comparative genomic hybridization, fluorescence in situ hybridization, and spectral karyotyping revealed the overall net copy number losses of hsa-let-7a and other miRNAs predicted to target KLK6.
  
  
  CONCLUSIONS
  The hsa-let-7 family member hsa-let-7a is a modulator of KLK6 protein expression that is independent of the KLK6 copy number status.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Bayani
authors.forename: Uros
authors.initials: U
authors.lastname: Kuzmanov
authors.forename: Punit
authors.initials: P
authors.lastname: Saraon
authors.forename: William A
authors.initials: WA
authors.lastname: Fung
authors.forename: Antoninus
authors.initials: A
authors.lastname: Soosaipillai
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Squire
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018628:Gene Dosage; D006801:Humans; D007610:Kallikreins / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D035683:MicroRNAs; C103551:KLK6 protein, human; D007610:Kallikreins