Enhancement of tumorigenic, metastatic and in vitro invasive capacity of rat mammary tumor cells by transforming growth factor-β

We investigated the effects of transforming growth factor-β (TGF-β) on biological behavior of a weakly malignant rat mammary carcinoma ER-1 cell line. TGF-β enhanced the tumorigenic and metastatic capacity of ER-1 cells and their in vitro invasiveness to rat mesothelial and endothelial cell. Further cell biological analysis indicated that the increased invasive and metastatic capacity of ER-1 cells by TGF-β was due to the increase in cell motility and adhesion to the mesothelial and endothelial cell monolayers. Thus, it is suggested that TGF-β acts on ER-1 cells as a progression-enhancing factor which stimulates their adhesive and motile activities.