HUMAN ENDOMETRIAL ADENOCARCINOMA CELL-LINES HEC-1B AND KLE SECRETE INSULIN-LIKE GROWTH-FACTOR BINDING PROTEIN-1 AND CONTAIN IGF-I RECEPTORS

The production of insulin-like growth factor binding proteins (IGFBP) with special reference to human IGFBP-1 was evaluated in five endometrial adenocarcinoma cell lines (HEC 1A, HEC 1B, KLE, RL952 and AN3CA) in continuous culture. Two of the cell lines (HEC 1B and KLE) produced immunoreactive IGFBP-1. The production was inhibited by clomiphene and progesterone, whereas estrogen, cortisol and insulin had no effect on IGFBP-1 secretion. The two cell lines which secreted immunoreactive IGFBP-1 also had IGF-I receptors, whereas the cell lines RL952 and AN3CA, not producing IGFBP-1, had no saturable IGF membrane binding sites. IGF-I receptor binding to HEC 1B and KLE cells was inhibited in the presence of purified IGFBP-1. In addition to IGFBP-1, the endometrial cancer cells secreted several other forms of IGFBPs as determined by cross-linking. Immunoprecipitation of IGF-BP complexes with a polyclonal antiserum against IGFBP-3 indicated that all cell lines secreted binding proteins antigenically related to IGFBP-3 with molecular weights ranging from 20 to 39 kDa.