Figure 3.

Decorin inhibited EGFR and EGFR phosphorylation in prostate of Pten^P-/- mice and human prostate cancer cells. (A) Prostate tissues from AP, DL, and VP of Pten^P-/- mice treated with decorin or saline (n = 2 mice each group) were homogenized with lysis buffer containing protease and phosphatase inhibitors. Protein extracts was analyzed by Western blots for EGFR, EGFR phosphorylation (Tyr 1068), and β-actin. (B) Cells were treated with decorin (1 and 2 µM) or biglycan (2 µM) for 48 hours. The cells were lysed, and EGFR and its phosphorylation (p-EGFR, Tyr 1068) were measured by Western blot analysis of 20-µg per well protein aliquots. Data shown are representative of three experiments with similar results. (C) PC3 cells were treated with decorin (2 µM) for 5, 10, or 20 minutes. Total proteins were used to measure EGFR and EGFR phosphorylation (Tyr 1068) by Western blot assay. Results are representative of two independent experiments. (D) LNCaP cells were treated with decorin (2 µM), AG1478 (2 µM), and/or EGF (100 ng/ml) for 10 minutes. Total proteins were analyzed by Western blot analysis with anti-phospho-EGFR (Tyr 1068) or anti-total EGFR antibodies. Results are representative of two independent experiments. (E) Cells were exposed to decorin (2 µM), biglycan (2 µM), AG1478 (2 µM), and/or EGF (100 ng/ml) for 48 hours. Cell number was measured by MTS. Values representing the mean ± SD (n = 4) with different letters indicate significant differences (P < .05). (F) PC3 and DU145 cells were exposed to EGFR kinase inhibitor, AG1478 (2 µM, pretreated for 30 minutes), decorin (2 µM), or biglycan (2 µM). Cell number was measured by MTS after 72 hours. Values representing the mean ± SD (n = 4) with different letters indicate significant differences (P < .05).