Heparin-binding (fibroblast) growth factors are potential autocrine regulators of esophageal epithelial cell proliferation

Abstract

A serum-free culture system supplemented with neural tissue extract for normal human esophagus was applied to the culture of mouse esophageal epithelium. Similar to mouse mesenchyme and skin epithelium, esophageal epithelial lines (MEE) emerged after serial culture. The cells had an apparent unlimited life-span, but retained morphology and other characteristics of normal epithelial cells. A screen for growth factors that stimulated growth of MEE cells in the absence of neural extract revealed that epidermal growth factor (EGF) and heparin-binding (fibroblast) growth factors (HBGF) were most effective. An HBGF-like activity was apparent in extracts of rapidly proliferating, but not quiescent MEE cells at low or confluent densities. A cloned cell line (MEE/C8) was selected from MEE cell cultures in the absence of neural extract. MEE/C8 cells proliferated independent of either EGF or HBGF at rates equal to MEE cells, cell extracts exhibited HBGF-like activity at all stages of proliferation, and the cells formed invasive tumors in syngenic hosts. The HBGF-like activity present in extracts of tumorigenic MEE/C8 cells had properties similar to HBGF-1 (acidic fibroblast growth factor).