Figure 5.

(A) Effect of Sant 7 on PGE₂-stimulated aromatase in proximal fibroblasts. IL-6 (50 ng ml⁻¹)+IL-6sR (100 ng ml⁻¹) stimulated aromatase activity to a greater extent than did PGE₂ (10 μM). Sant 7, which blocks IL-6+IL-6sR-stimulated aromatase activity, significantly reduced the ability of PEG₂ to stimulate aromatase activity in these fibroblasts. To examine if the effects of Sant 7 were reversible (Rev), one set of fibroblasts (IL-6+IL-6sR (Rev)) was preincubated with Sant 7 for 12 h and then Sant 7 was removed by washing the cells with phosphate-buffered saline. IL-6+IL-6sR stimulated aromatase activity in these cells after washing to a similar extent to fibroblasts not exposed to Sant 7, showing that Sant 7 does not act in an irreversible manner. (a, P<0.001 vs controls; b, P<0.0001 vs PGE₂; c, P<0.001 PGE₂+Sant 7 vs PGE₂). (B) As for the legend to Figure 4A but carried out using breast tumour-derived fibroblasts (a, P<0.001 vs controls; b, P<0.001 vs PGE₂; c, P<0.05 vs controls; d, P<0.001 vs PGE₂, means±s.d., n=3).