Indirect mitogenic effect of transforming growth factor-beta on cell proliferation of subconjunctival fibroblasts

Invest Ophthalmol Vis Sci. 1998 Mar;39(3):481-6.


Purpose: To understand the mechanism of fibrosis after filtering surgery for glaucoma, the effect of transforming growth factor-beta (TGF-beta) was studied in subconjunctival fibroblasts (SCFs). TGF-beta, universal inhibitor of cell proliferation, stimulates the cell proliferation of fibroblasts. SCFs were evaluated for their production of TGF-beta and fibroblast growth factor 2 (FGF-2) to determine whether TGF-beta may be an indirect mitogen acting through the induction of an endogenous growth factor, or factors, that then acts as the direct mitogen in an autocrine manner.

Methods: Cell proliferation was determined either by counting cell numbers or by analyzing the incorporation of [3H]thymidine into DNA. The synthesis of TGF-beta and FGF-2 was analyzed by immunoprecipitation and immunoblotting.

Results: TGF-beta 1, TGF-beta 2, and TGF-beta 3 stimulated the cell proliferation of SCFs in a dose-dependent manner. The media conditioned by SCFs, which were subsequently activated by acid, stimulated cell proliferation of corneal stromal fibroblasts. When the acid-activated media conditioned by SCFs were immunoprecipitated, respectively, either with anti-TGF-beta 1 and TGF-beta 2 antibodies or with anti-TGF-beta 3 antibody, TGF-beta s, with an apparent molecular size of 25 kDa, were detected, whereas SCFs produced an 80-kDa latent form of TGF-beta 1. Interestingly, SCFs produced and secreted an 18-kDa extracellular isoform of FGF-2, the synthesis of which is further stimulated by TGF-beta 1 and TGF-beta 3, respectively, whereas the neutralizing antibody to FGF-2 and the FGF-2-specific antisense oligonucleotide primers inhibited the stimulatory activities of TGF-beta 1 in SCFs.

Conclusions: These findings indicate that SCFs produce TGF-beta and FGF-2 and that FGF-2 seems to be the direct stimulator of TGF-beta-mediated cell proliferation in SCFs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Count
  • Cell Division / drug effects
  • Cells, Cultured
  • Conjunctiva / cytology
  • Conjunctiva / drug effects*
  • Conjunctiva / metabolism
  • Culture Media, Conditioned
  • DNA / biosynthesis
  • DNA Replication
  • Dose-Response Relationship, Drug
  • Fibroblast Growth Factor 2 / biosynthesis
  • Fibroblast Growth Factor 2 / genetics
  • Fibroblasts / cytology
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Immunoblotting
  • Mitogens / pharmacology*
  • Oligonucleotides, Antisense / pharmacology
  • Precipitin Tests
  • Rabbits
  • Transforming Growth Factor beta / biosynthesis
  • Transforming Growth Factor beta / pharmacology*


  • Culture Media, Conditioned
  • Mitogens
  • Oligonucleotides, Antisense
  • Transforming Growth Factor beta
  • Fibroblast Growth Factor 2
  • DNA