Autocrine growth mechanism by transforming growth factor (TGF)‐β1 and TGF‐β1‐receptor regulation by epidermal growth factor in a human endometrial cancer cell line IK‐90

Abstract

Transforming growth factor‐β1 (TGF‐β1) enhanced cell proliferation in a concentration‐dependent manner in a human endometrial cancer cell line, IK‐90. Scatchard analysis of TGF‐β1 receptor in IK‐90 cells, using 125I‐TGF‐β1 as a ligand, revealed the presence of a class of high‐affinity TGF‐β1 receptors (2,000 sites per cell, KD = 74pM). Moreover, IK‐90 cells produced and secreted TGF‐β1: TGF‐β1 messenger RNA was detected at 2.5 and 4.0 kb by Northern‐blot analysis using 32P‐labeled TGF‐β1 cDNA as a probe, and TGF‐β1 activity in conditioned medium by the inhibition of 3H‐thymidine uptake into CCI 64 mink lung epithelial cells. We investigated the regulation of TGF‐β1 receptor by 4 kinds of growth factor: epidermal growth factor (EGF) but not TGF‐β1 insulin or insulin‐like growth factor‐I increased the level of TGF‐β1 binding sites in a concentration‐ and time‐dependent manner. These findings suggest that TGF‐β1 may be a potential autocrine growth factor in a human endometrial cancer cell line IK‐90 and that this autocrine mechanism may be affected by EGF. Copyright © 1993 Wiley‐Liss, Inc., A Wiley Company