Chromosomal characteristics and malignancy of urothelial cells from carcinogen-treated rats

Epithelial cells of bladders from male Fischer 344 rats that had been treated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) or N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) were cultured and examined for chromosomal changes, anchorage independence in vitro, and transplantability in vivo. Numerical but not structural changes of chromosomes were significantly greater in the FANFT group than in the BBN group. Urothelial cell lines that demonstrated prolonged life span and loss of anchorage dependency were established from 14 of these rats, but only nine of them demonstrated tumorigenicity in the nude mouse model. Two of these transplantable cell lines and R4909, a transplantable bladder cell line derived from a 3-methylcholanthrene-treated rat, have normal chromosomes. The present study demonstrates a carcinogen-related chromosome change in the urothelial cells, but the relationship between malignancy and specific chromosomal changes is not clear.