FIGURE 4.

Demethoxycurcumin (DMC) downregulated HER2 expression by dissociating of Hsp90 from HER2. (A) RT4 cells were cultured with 20 μg/ml cycloheximide (CHX) in the presence or absence of 20 μM DMC for the indicated times followed by Western blot for HER2 and β‐Actin. (B) RT4 cells were pretreated with MG132 (20 μM) for 30 min followed by 20 μM DMC for 9 h, and Triton X‐100–soluble and Triton X‐100–insoluble cell lysates were prepared and a followed by Western blotting for HER2 and β‐actin. (C) RT4 cells were treated with 20 μM DMC for the indicated periods. Lysates of RT4 cells were immunoprecipitated with antibodies against HER2 and immunoblotting was performed using anti‐HER2 and anti‐Hsp90 antibodies. (D) RT4 cells were treated with Hsp90 inhibitor 17AAG (10 μM) or DMC (20 and 40 μM) for 48 h followed by Western blot for HER2, Raf‐1, AKT, CDK4, and β‐actin. Western blot data presented are representative of those obtained in at least three separate experiments. The values below the figures represent change in protein expression of the bands normalized to β‐actin