In vitro invasiveness of human bladder cancer from cell lines and biopsy specimens.

Aggregates prepared from cell lines established from a human transitional cell carcinoma of the urothelium (Hu 456) or from apparently normal urothelium before (Hu 609) and after phenotypic transformation (Hu 609T) were confronted with fragments of embryonic chick cardiac muscle in organ culture. In this assay a correlation was found between in vitro invasiveness of animal cell lines and their capacity to produce invasive tumours in syngeneic animals. The invasiveness of cells from established human urothelial lines was compared to the invasiveness of cells from established human urothelial lines was compared to the invasiveness of cells from fresh biopsy specimens of a normal urothelium, a non-invasive papilloma, and a metastasizing transitional cell carcinoma. Cells from all established lines (Hu 609, Hu 609T and HU 456) and from the biopsy specimens of the transitional cell carcinoma occupied and eventually replaced the cardiac muscle by contrast with cells from the normal urothelium or from the non-invasive papilloma. We concluded that the organ culture assay for invasiveness might be used to define malignancy of human bladder cell lines and to follow the various steps during the acquisition of invasiveness in vitro.