EFFECTS OF EPIDERMAL GROWTH-FACTOR ON THE INVASION ACTIVITY OF THE BLADDER-CANCER CELL-LINE

Purpose: Epidermal growth factor (EGF) is excreted in high concentrati ons in the urine and stimulates urothelial cell growth. The cultured b ladder cancer cell line KU-1 was used to study the molecular mechanism s by which EGF affects urothelial tumor growth and invasion activity. Materials and Methods: KU-1 cells were grown in cell culture in the pr esence or absence of EGF. Anchorage-independent cell growth assays and Matrigel invasion assays were performed. Expression of cytokeratins w as examined by Northern and Western blot analyses. Chloramphenicol ace tyltransferase assays were used to determine whether EGF stimulated ma trix metalloproteinase expression. Results: EGF enhanced anchorage-ind ependent growth in soft agar and increased the number of cells penetra ting into a Matrigel membrane. A transient transfection assay revealed that EGF increased the promoter activities of the matrix metalloprote inase 1 and 9 genes in KU-1 cells. Moreover, the morphology of KU-1 ce lls changed after the addition of EGF to the culture medium. Western a nd Northern blot analyses demonstrated that EGF decreased cytokeratin 19 expression, but did not affect expression of cytokeratin 8 or 18. C onclusion: EGF increased the invasive activity of KU-1 bladder cancer cells in part by increasing the secretion of matrix metalloproteinases . Morphologic changes may result from altered composition of cytoskele tal proteins.