Transforming growth factor-beta 1 modulates chondrocyte responsiveness to 17 beta-estradiol

This study examined the interrelationship between transforming growth facto r-beta1 (TGF-beta 1) and 17 beta-estradiol (E-2) in the regulation of growt h plate chondrocytes. To determine whether TGF-beta 1 modulates chondrocyte response to E-2, we used cells isolated from the resting zone (RC) and gro wth zone (GC) of costochondral cartilage. Confluent, fourth-passage culture s were pretreated with rhTGF-beta 1 for 24 h, followed by treatment with E- 2 for 24 h. The effect of TGF-beta 1 and E-2 alone, or the sequential combi nation, were examined by measuring [H-3]-thymidine incorporation (prolifera tion), alkaline phosphatase (AP) specific activity (differentiation), and [ S-35]-sulfate incorporation (matrix synthesis). TGF-beta 1 alone increased [H-3]-thymidine incorporation in both female and male RC and GC cells, but E-2 affected this parameter only in RC cells, causing a dose-dependent decr ease. At the highest concentration of TGF-beta 1 and E-2, [H-3]-thymidine i ncorporation in female CC cells was the same as seen in untreated control c ultures. In male GC cells, [H-3]-thymidine incorporation in cultures treate d with TGF-beta 1 and E-2 exhibited a comparable increase, as was seen in c ultures treated with TGF-beta 1 alone. TGF-beta 1 caused a biphasic stimula tion in AP that was maximal at 0.22 ng/mL, in both female and male RC and G C cells. E-2, however, affected only female cells. Whereas the effect of TG F-beta 1 predominated in RC and GC male cells, the biphasic stimulation cau sed by E-2, maximal at 10(-9) M, predominated in female RC cells. In female GC cells, however, TGF-beta 1 caused a synergistic response, resulting in enhanced AP specific activity in cultures pretreated with 0.22 ng/mL of TGF -beta 1 and 10(-8) M E-2. TGF-beta 1 alone caused dose-dependent increases in [S-35]-sulfate incorporation in female RC and GC cells, as well as in ma le GC cells, but had no effect on male RC cells. E-2 affected only female c ells. TGF-beta 1 potentiated the effect of E-2 on this parameter, resulting in synergistic increases in the female cells. This is the first demonstrat ion of a gender-specific response to TGF-beta 1 in chondrocytes. These resu lts suggest that chondrocyte response to a systemic hormone such as E-2 can be modulated by local regulatory agents such as TGF-beta 1.