title: The New Immortalized Uroepithelial Cell Line HBLAK Contains Defined Genetic Aberrations Typical of Early Stage Urothelial Tumors.
abstract: Background:Cell culture models of normal urothelial cells are important for studying differentiation, disease mechanisms and anticancer drug development. Beyond primary cultures with their limitations in lifespan, interindividual heterogeneity and supply, few conditionally immortalized cell lines with limited applicability due to partial transformation or impaired differentiation capacity are available. We describe characteristics of the new spontaneously immortalized cell line HBLAK derived from a primary culture of uroepithelial cells.Objective:To characterize utility and limitations of HBLAK cells as an urothelial cell culture model.Methods:Differentiation markers were investigated by immunofluorescence and RT-PCR, genetic changes by standard karyotyping, array-CGH, PCR, RT-PCR and exome sequencing; expression of p53 and p21 by Western blotting.Results:HBLAK cells proliferated for >50 passages without senescing. They expressed cytokeratins of basal urothelial cells. Terminal differentiation markers appeared only after induction of differentiation by specific protocols. The karyotype was stable, with few chromosomal changes, especially gains of chromosomes 5 and 20 and a chromosome 9p21 deletion resulting inp16INK4Aloss. A C228TTERTpromoter mutation was present, but no other mutation typical of urothelial carcinoma.TP53was wild-type and the cell cycle was arrested in response to genomic stress.Conclusions:HBLAK cells retain some differentiation potential and respond to cytotoxic agents similar to normal urothelial cells, but contain genetic changes contributing to immortalization in urothelial tumors. HBLAK may be valuable for evaluating the tumor specificity of novel cancer drugs, but may also be applied as an urothelialin vitrocarcinogenesis model.
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Michèle J
authors.initials: MJ
authors.lastname: Hoffmann
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Koutsogiannouli
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Margaretha A
authors.initials: MA
authors.lastname: Skowron
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Pinkerneil
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Niegisch
authors.affiliation: Institute for Human Genetics, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Artur
authors.initials: A
authors.lastname: Brandt
authors.affiliation: Biological and Medical Research Center (BMFZ), Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Stepanow
authors.affiliation: Institute for Human Genetics, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Rieder
authors.affiliation: Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany.
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Schulz
keywords: CDKN2A; Immortalization; bladder cancer; cell culture model; normal urothelial cells; p53; telomerase; urothelial differentiation