280B down-regulates p53 signaling in prostate cancer cells.

<p>(<b>A, C</b>) LNCaP, C81, CWR22-RV1 cells were transfected with control (−) or 280B siRNA (+) and p53, survivin, p21, and 280B expression levels were measured by Western blotting (A) or real-time PCR (C). (<b>B, D</b>) C81 cells were infected with empty (−) or 280B adenovirus (+) and p53, survivin, p21 and 280B expression levels were measured by Western blotting (B) or real-time PCR (D). All expression levels are relative to the first condition (C and D), and it was set to 1. (<b>E</b>) C81 cells were transfected with 0.2 µg p53-Luc and control (−), or 280B (+) siRNA, in the presence of control or p53 siRNA. Transcriptional activity of p53 activity was quantified by measuring Luciferase activity. All activities are relative to the first condition, and this activity was set to 1. (<b>F, G</b>) Cells from (E) were subjected to Western blotting for p53, Survivin, p21, and 280B (F), and measurement of cell density by MTT assay (G). β-actin served as a loading control in the Western blots. Bar graphs represent averages of three independent experiments plus SD. Asterisks indicate statistical significance (P<0.02).