Evidence for a role of FGF-2 and FGF receptors in the proliferation of non-small cell lung cancer cells

Abstract

Basic fibroblast growth factor (FGF-2) has been implicated in the progression of human tumours via both autocrine and paracrine (angiogenic) activities. We investigated the expression of FGF-2 and FGF receptors (FGFR-1 to -4) in NSCLC cell lines (N = 16), NSCLC surgical specimens (N = 21) and 2 control cell lines. Our data show that almost all NSCLC cells produce elevated levels of FGF-2 and FGFR in vitro and in vivo. FGF-2 expression did correlate with a short doubling time as well as with potent anchorage-independent growth of NSCLC cell lines. In contrast with control cells, NSCLC cells did not secrete considerable amounts of FGF-2 into the extracellular space. Expression levels of FGFR-1 and -2 in NSCLC cell lines correlated with FGF-2 production. FGFR were located at the plasma membranes in some low FGF-2-producing NSCLC and control cell lines. These cells were sensitive to the proliferative effect of recombinant FGF-2 (rFGF-2). In NSCLC cell lines with an enhanced FGF-2 production, representing the majority studied, FGFR localisation was predominantly intracellular. These cells were insensitive to both the proliferative effect of rFGF-2 and growth inhibition by FGF-2-neutralising antibodies. In contrast, several agents antagonised FGF-2 intracellularly impaired growth of almost all NSCLC cell lines. Our data suggest a role of FGF-2 and FGFR in the growth stimulation of NSCLC cells possibly via an intracrine mechanism.