Sharon C Doherty | PubMed Health

PubMed2006

Gene expression in normal urothelium depends on location within the bladder: a possible link to bladder carcinogenesis.

OBJECTIVES: Clinical studies have shown that more than 70% of primary bladder tumours arise in the area around the ureteric orifice. In this study a genomic approach was taken to explore the molecular mechanisms that may influence this phenomenon. METHODS: RNA was isolated from each individual normal ureteric orifice and the dome biopsy from 33 male patients. Equal amounts of the pooled ureteric orifice and dome mRNAs were labelled with Cy3 and Cy5, respectively before hybridising to the gene chip (UniGEM 2.0, Incyte Genomics Inc., Wilmington, Delaware, USA). RESULTS: Significant changes (more than a twofold difference) in gene expression were observed in 3.1% (312) of the 10,176 gene array: 211 genes upregulated and 101 downregulated. Analysis of Cdc25B, TK1, PKM, and PDGFra with RT-PCR supported the reliability of the microarray result. Seladin-1 was the most upregulated gene in the ureteric orifice: 8.3-fold on the microarray and 11.4-fold by real time PCR. CONCLUSIONS: Overall, this study suggests significant altered gene expression between these two anatomically distinct areas of the normal human bladder. Of particular note is Seladin-1, whose significance in cancer is yet to be clarified. Further studies of the genes discovered by this work will help clarify which of these differences influence primary bladder carcinogenesis.

Adult↗

PubMed2003

Cell cycle checkpoint function in bladder cancer.

BACKGROUND: Cell cycle checkpoints function to maintain genetic stability by providing additional time for repair of DNA damage and completion of events that are necessary for accurate cell division. Some checkpoints, such as the DNA damage G1 checkpoint, are dependent on p53, whereas other checkpoints, such as the decatenation G(2) checkpoint, are not. Because bladder transitional cell carcinomas (TCCs) often contain numerous chromosomal aberrations and appear to have highly unstable genomes, we analyzed cell cycle checkpoint functions in a panel of TCC lines. METHODS: Cell cycle arrest was induced in normal human fibroblasts (NHF1-hTERT) and normal human uroepithelial cells (HUCs), and TCC lines and checkpoint functions were quantified using flow cytometry and fluorescence microscopy. The inducers and checkpoints were ionizing radiation (i.e., DNA damage) (G1 and G2 checkpoints), the mitotic inhibitor colcemid (polyploidy checkpoint), or the topoisomerase II catalytic inhibitor ICRF-193 (decatenation G2 checkpoint). Four of the five TCC lines expressed mutant p53. RESULTS: HUCs had an effective G1 checkpoint response to ionizing radiation, with 68% of cells inhibited from moving from G1 into S phase. By contrast, G1 checkpoint function was severely attenuated (<15% inhibition) in three of the five TCC lines and moderately attenuated (<50% inhibition) in the other two lines. NHF1-hTERT had an effective polyploidy checkpoint response, but three of five TCC lines were defective in this checkpoint. HUCs had effective ionizing radiation and decatenation G2 checkpoint responses. All TCC lines had a relatively effective G2 checkpoint response to DNA damage, although the responses of two of the TCC lines were moderately attenuated relative to HUCs. All TCC lines had a severe defect in the decatenation G2 checkpoint response. CONCLUSION: Bladder TCC lines have defective cell cycle checkpoint functions, suggesting that the p53-independent decatenation G2 checkpoint may cooperate with the p53-dependent G1 checkpoints to preserve chromosomal stability and suppress bladder carcinogenesis.

Carcinoma, Transitional Cell↗