Latent forms of transforming growth factor-beta 2 (TGF-beta 2) in breast cyst fluid.

Transforming growth factor-beta (TGF-beta) is secreted by cells in high molecular weight, latent forms and the in vivo mechanisms for the activation remain largely an enigma. Women who have palpable breast cyst with intracystic Na/K < 3 may have a higher risk of developing breast cancer than those with intracystic Na/K > 3. Finding of significantly higher concentrations of TGF-beta 2 in the Na/K > 3 group than Na/K < 3 group may explain the lower risk of breast cancer in the Na/K > 3 group. The aim of the present study was to characterise the latent forms of TGF-beta 2 in breast cyst fluid using HPLC, affinity chromatography, SDS-PAGE and immunostaining techniques. We found that TGF-beta 2 is present in high molecular weight, latent forms in breast cyst fluid: as a complex, probably with alpha 2-macroglobulin and a 56 kD protein which is likely to be a precursor form of TGF-beta 2.