RELEASE OF FIBROBLAST GROWTH-FACTOR-I BY HUMAN SQUAMOUS-CELL CARCINOMA CORRELATES WITH AUTOCRINE CELL-GROWTH

A squamous cell carcinoma cell line Nakata proliferated in serum-free culture and was not responsive to exogenous fibroblast growth factor-1 (FGF-1). Immunostaining revealed that Nakata cells expressed FGF-1 in their cytoplasms and nuclei. Two molecular mass species of FGF-1 (16 and 18 kDa) were identified in cell extracts by Western blot. These ce lls also expressed high-affinity FGF-1 binding sites (Kd = 360 pM, 28 000 sites/cell). The results of cross-linking with [I-125]FGF-1 demons trated the presence of two bands with molecular masses of 160 and 140 kDa. The addition of FGF-1 specific antisense oligonucleotides at 25 m u M to Nakata cells resulted in an 82% inhibition in cell growth and s uppressed FGF-1 expression. This effect was dose-dependent and specifi c, because sense oligonucleotides were ineffective in inhibiting cell growth. In addition, Nakata cell growth was suppressed by an anti-FGF- 1 neutralizing antibody, which resulted in a 52% inhibition at 8 mu g/ ml. These results demonstrate that Nakata cells produce FGF-1, and ind icate that this growth factor acts in an autocrine manner by interacti ng with FGF-1 binding sites on Nakata cells.