FIG. 5.
Signaling pathways of SRC-3-induced cell growth in stable LNCaP-SRC-3 cells. (A) Schematic overview of the PI3K/AKT/mTOR signaling cascade, linking receptor tyrosine kinase-derived signals to protein synthesis and cell growth regulatory mechanisms. (B) Activation of the PI3K/AKT/mTOR pathway by treatment with mifepristone with LNCaP-SRC-3 stable cells. Immunoblot analysis of clone no. 12 and parental LNCaP cells showed that stimulation with mifepristone (10−8 M) for 12 h increased the phosphorylation of AKT, S6K1, and GSK3 (lane 4) compared with controls (lanes 1 to 3). Treatment of SRC-3 stable cell lines with kinase inhibitors for PI3K (10 μM LY294002 [LY]) (lane 5), mTOR inhibitor (2 ng/ml rapamycin [RAP]) (lane 6), and an inhibitor of Erk1/2, PD98059 (PD) (lane 7) is shown. Similar results are also seen for other stable clones.