Fig. 4.

Decrease in AR protein induced by omega-3 PUFA. (A) Effects in vivo: western blot of AR in prostate tumor tissues from allografts or transgenics fed omega-3 and omega-6 diets. Compared with omega-6 diet group, omega-3 diet reduced AR expression in transgenics (P = 0.02, Student's t-test). A similar trend was seen in allografts. Bars are standard deviations. AR messenger RNA was quantified by real-time reverse transcription–polymerase chain reaction. No statistically significant difference was seen between tumor samples from mice on omega-3 and omega-6 diet. (B) Effects on multiple cell lines: human PTEN-negative prostate tumor cells (C4-2 and LNCaP), mouse Pten-null cells (Pten^−/−) and in vitro Pten-deleted mouse prostate cells (Pten^L/L+Cre) were incubated with AA, DHA or BSA. AR protein expression was determined by western blotting. AR messenger RNA in C4-2 cells was quantified by real-time reverse transcription–polymerase chain reaction. DHA treatment reduced AR protein, but not messenger RNA levels. Bars are standard deviations. (C) Kinetics: C4-2 cells were treated with AA, DHA or BSA for 24, 48 and 72 h. AR protein expression was determined by western blotting. DHA treatment reduced the level of AR protein. (D) Subcellular distribution of AR protein: C4-2 cells were treated with AA, DHA or BSA for 72 h. Cytosolic and nuclear fractions were prepared and AR protein expression was determined by western blotting. Lamin B1 and α-tubulin were used as loading controls for nuclear and cytosolic fractions, respectively. DHA treatment reduced the level of AR protein to a similar extent in both fractions, suggesting that DHA had no effect on AR nuclear translocation. Analysis of variance was used to assess the significance of data. P < 0.05 was considered as significant.