RELATIONSHIP BETWEEN BASIC FIBROBLAST GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-BETA-2 IN BREAST CYST FLUID

Women with ''apocrine'' breast cysts (usually having intracystic Na/K < 3) may have a higher risk of developing breast cancer than women wit h breast cysts lined by flattened epithelium (usually having intracyst ic Na/K > 3). In this study the concentrations of basic fibroblast gro wth th factor (bFGF), a potent mitogen, and transforming growth factor -beta 2 (TGF-beta 2), which exerts a growth inhibitory effect on epith elial cell types, were measured in breast cyst fluid and their relatio nship studied. Both growth factors were measured by ''sandwich'' enzym e immunometric assays. The concentrations of both bFGF and TGF-beta 2 were significantly higher (P < 0.001) in the Na/K > 3 group (median 44 4 fmol/L, range: < 56 fmol/L - 7,890 fmol/L. n = 23 and median 1,776 p mol/L, range: 20.4 pmol/L - 5,000 pmol/L, n = 19 respectively) than in the Na/K < 3 group (median < 56 fmol/L. range: < 56 fmol/L - 2,722 fm ol/L, n = 21 and median 176 pmol/L, range: 12 pmol/L - 1,940 pmol/L, n = 23 respectively). Significant positive correlations were found betw een bFGF and TGF-beta 2 (r(S) = 0.496, n = 37, P = 0.002), bFGF and Na /K (r(S) = 0.599, n = 44, P < 0.001) and TGF-beta 2 and Na/K (r(S) = 0 .521, n = 42, P < 0.001). The significantly higher concentrations of t he growth inhibitory TGF-beta 2 in the Na/K > 3 cyst group may provide an explanation for the lower risk of breast cancer which has been obs erved in this group of women. The role of bFGF in mammary carcinogenes is is unclear as lower levels of this growth factor are present in bre ast cancer tissue and breast cancer cell lines than in normal breast t issue and cell lines. The positive correlation between bFGF and TGF-be ta 2 may indicate regulation by a common factor or that one of these g rowth factors may regulate the production of the other. This is the su bject of further study.