Figure 1.

Depletion of Pirh2 increased p27 expression in head and neck squamous cell carcinoma (HNSCC) cell lines. (a) Depletion of Pirh2 induced p27 accumulation in HNSCC cells. Ho‐u‐1 and Ho‐1‐N‐1 cell lines were transfected with Pirh2 or control short interfering RNA (siRNA). Thirty µg of protein was subjected to western blot analysis using anti‐Pirh2 or anti‐p27 antibodies. β‐Actin blot was used as a loading control. The lower graph shows the quantitative density of Pirh2 and p27 protein expression detected by western blotting. (b) The effect of Pirh2 siRNA transfection on cell proliferation in vitro. Correlation was analyzed by Student's t‐test. Results are from three independent experiments. (c) Effects of Pirh2 depletion on cell cycle progression. P‐value of G₁ to S ratios were analyzed by Student's t‐test. Results are from three independent experiments. (d) Accumulation of p27 by depletion of Pirh2 was detected by immunohistochemical analysis of Pirh2 and p27 in Ho‐1‐u‐1 cells. Ho‐1‐u‐1 cells were transfected with Pirh2 or control siRNA. Residual cells were packed as a cell block and then subjected to immunocytochemical analysis using anti‐Pirh2 or anti‐p27 antibodies (×200; magnified image, ×800). (e) Pirh2‐ or p27‐positive cells were counted and their rates calculated. Correlation was analyzed by Student's t‐test. The results are from three specimens.