ALDH1 expression, and biological features of ALDH1-positive and ALDH1-negative RCC cells.

<p>(A) The expression of ALDH1 in SP cells and NSP cells in ACHN and KRC/Y. The ALDH1-positive cell rates in ACHN and KRC/Y were 15.3% and 6.5%, respectively. (B) Comparison of cell growth among control cells, cells treated with Sorafenib or IFNα, and cells exposed to hypoxia in ACHN. Cell growth was measured at 48, 72 or 96 hours after drug treatment or exposure to hypoxia. Cell growth after drug treatment or exposure to hypoxia was significantly suppressed as compared with control (* <i>P</i><0.005, ** <i>P</i><0.0001 vs. control). (C) The percentage of ALDH1-positive cells in cells treated with Sorafenib or IFNα, or cells exposed to hypoxia for 48, 72 or 96 hours. The percentage of ALDH1-positive cells in cells treated with Sorafenib or IFNα, or cells exposed to hypoxia for 96 hours was higher as compared with the normal condition. The experiments were repeated twice, and almost identical results were obtained. A representative figure of our experiments is shown. (D) Sphere forming ability between ALDH1-positive cells and ALDH1-negative cells. The sphere formation of ALDH1-positive cells in ACHN and KRC/Y was higher than that of ALDH1-negative cells. The experiments were repeated twice, and almost identical results were obtained.