ABSTRACT
This chapter discusses some of the techniques which have been used by researchers and others to detect growth factor production and secretion in human epithelial cells. It also discusses some of the specific growth factors which have been detected in normal and neoplastic human epithelial cells in situ and in culture. The classical approach for detection of secreted growth factors from a tumor cell line was described by Marquardt and Todaro in 1982. These investigators used biochemical methods to purify TGF-α from large volumes of medium conditioned by sarcoma virus-transformed rat embryo fibroblasts or a human melanoma cell line. TGF-α has many functions in addition to stimulation of cell growth and, for many, is more potent than epidermal growth factor (EGF). The chapter demonstrates the presence of TGF-α and IGF-I in medium conditioned by A549 cells. The experimental results indicated that other unknown growth-stimulating peptides were present in A549 cell-conditioned medium.
