Figure 4

Examples of the Western blot analysis of the ERK 1/2 and AKT phosporylation after exposure to IGF-1 (100 ng/mL), 15dPGJ2 (2 µM) and rosiglitazone (10 µM) in PC-3 cells cultured with 0.5% FBS. The time of exposure was 5 min, 15 min, 30 min, 60 min, and 6 h (written on the figure as 5′ 15′ 30′ 60′ and 6h). Under identical experimental conditions, we also have examined the activation of ERK1/2 and AKT following combination treatments using IGF-1 plus 15dPGJ2 and IGF-1 plus rosiglitazone (ROS). Note that IGF-1 activated both the ERK 1/2 and AKT phosphorylation as published previously. In addition, 15dPGJ2 activated ERK1/2 phosphorylation while it did not activate AKT phosphorylation. Furthermore, 15dPGJ2 did not alter the IGF-1-mediated activation of ERK1/2 and AKT phosphorylation. In contrast, ROS did not alter ERK1/2 and AKT phosphorylation of PC-3 cells when given as a single agent, however, it blocked partially the IGF-1-mediated ERK1/2 phosphorylation and attenuated completely the IGF-1-mediated AKT phosphorylation of PC-3 cells when given in combination with IGF-1. The inhibition of AKT phosphorylation by rosiglitazone was not altered when the cells were pre-incubated by the PPARγ antagonist GW9662.