Direct Demonstration of an Autocrine Mechanism in EMS-Induced, Tumorigenic Mutants of the Growth Factor-Dependent Hemopoietic Cell Line, FDC-P1

Abstract

A growth factor-dependent hemopoietic cell-line, FDC-P1, was treated with a chemical mutagen, EMS, and a number of growth factor-independent variants isolated. Six lines have been extensively analyzed with respect to their growth kinetics, morphology, karyotype, tumorigenicity, and hemopoietic growth factor production. Four lines produced at least one growth factor, subsequently demonstrated to be GM-CSF, while two lines showed no evidence of hemopoietic growth factor production. The observation that the autonomous proliferation of those EMS-derived cell lines that produced GM-CSF can be inhibited by incubation in growth media containing 10-50 microM anti-sense GM-CSF oligonucleotides demonstrated directly that the autonomous behavior of these cells is based on an autocrine mechanism. The induction of the expression of the GM-CSF gene represents a rare class of EMS-induced mutants, and is strongly suggestive of repressor inactivation rather than promoter activation.