HUMAN BLADDER-CARCINOMA CELL-LINES AS INDICATORS OF ONCOGENIC CHANGE RELEVANT TO UROTHELIAL NEOPLASTIC PROGRESSION

Analysis of human tumour-derived cell lines has previously resulted in the identification of novel transformation-related elements and provi ded a useful tool for functional studies of different genes. To establ ish the utility of such cell lines as indicators of change relevant to urothelial cancer, we have characterised the expression of five genes (p53, MDM2, Rb, E-cadherin, APC) within a panel of human bladder carc inoma cell lines. Using single-strand conformation polymorphism (SSCP) and direct sequencing, p53 mutations were identified in 7/15 (47%) ce ll lines reflecting events reported in bladder rumours. Immunohistoche mical analysis of p53 in cultured cells and in paraffin-embedded secti ons of xenografts from the cell line panel revealed discordant results . An absence of p53 nuclear staining was associated with an exon 5 mut ation in EJ and with multiple p53 mutations found in J82. Two cell lin es positive for p53 staining in the absence of detectable mutation dis played overexpression of MDM2 (PSI, HT1197) in Western blot analysis. Loss or aberrant Rb expression was recorded in 5/15 (TCCSUP, SCaBER, 5 637, HT1376, J82) cell lines. Absence of E-cadherin was recorded in 5/ 15 cell lines (TCCSUP, EJ, KK47, UM-UC-3, J82) with loss of alpha-cate nin in immunoprecipitated E-cadherin complexes of CUBIII. Western blot analysis of APC revealed a truncated protein in 1/15 (CUBIII) cell li nes. The characterisation of oncogenic events within this panel of hum an bladder carcinoma cell lines establishes a representation of change observed in bladder tumours and better defines the genotypic backgrou nd in these experimental human cell models of neoplastic progression.