Distribution of marker chromosomes in relation to histologic grade in bladder cancer

Detection of genetic alterations in primary bladder carcinoma with dual-color and multiplex fluorescence in situ hybridization

Cytogenetic studies of bladder cancer have shown several nonrandom aberrations. Numerical aberrations of both sex chromosomes were investigated in 32 primary bladder tumors with bicolor fluorescence in situ hybridization (FISH). Loss of chromosome Y and overrepresentation of chromosome X were observed in subgroups of male patients. Chromosome X was represented normally in female patients. Two of the above primary bladder tumors, a transitional cell carcinoma (TCC) and an adenocarcinoma, were further analyzed with both multiplex FISH (24-color M-FISH) and G-banding. Both cases exhibited 1) common breakpoints on 5q11 approximately q12 and 15q24; 2) involvement of the pericentromeric area of chromosome 13; 3) structural abnormalities of chromosomes 8 and 17, with loss of material on the short arm; 4) structural abnormalities involving chromosome 11; and 5) loss of chromosome Y. The TCC case also exhibited structural abnormalities of chromosome 9, resulting in loss of 9q. The combined G-banding and M-FISH findings could help reveal regions potentially involved in bladder tumorigenesis.

In vitro karyotype evolution and cytogenetic instability in the non-tumorigenic human breast epithelial cell line HMT-3522

The "spontaneously" immortalized cell line HMT-3522, derived from a fibrocystic breast lesion, is used as a model for premalignant breast epithelium. During 205 passages the cytogenetic evolution was followed. The results were compared with our earlier results on oncogene expression and growth factor requirements. During in vitro growth, gain and loss of markers, loss of normal chromosomes, and duplication of the chromosome complement could be demonstrated. The variability increased during in vitro growth. This variability, probably created randomly, leads to cells with different growth capacities, from which sidelines may be selected and become stemlines. The karyotypic evolution (including polyploidization) demonstrated here may be a result of genetic instability and heterogeneity. Although tumorigenicity was not achieved, either due to lack of cancer-specific gene alterations or to lack of proper selection pressure, the results suggest an ongoing process towards malignancy.

Genetics of transitional cell carcinoma

Several models of genetic events which define the origin and progression of human tumors have been elucidated over the last several years. These models suggest that the study of tumors at the level of both the chromosome and the gene can be useful in elucidating molecular events in tumor progression and in determining the biologic behavior of individual tumors. The genetics of transitional cell carcinomas are reviewed with emphasis on potential mechanisms of tumorigenicity and the clinical utility of genetic markers.