Zn-curc impairs survival of mutant p53-carrying cells. (A) Tumor cells (4 x 104) were plated in 60 mm dish and 24 h later treated with increased amount of Zn-curc (20, 50, 100 μM). Twenty-four hours later, plates were washed with PBS and fresh medium was added. Death-resistant colonies were stained with crystal violet 14 days later. (B) Death-resistant colonies as in (A) were counted and plotted as percentage ± SD of two independent experiments performed in duplicate. (C) Cells (3 x 105) were plated at subconfluence in 60 mm dish and the day after treated with Zn-curc for 24 and 48 h. Cell viability was measured by trypan blue exclusion assay and expressed as percentage ± SD of two independent experiments. (D) Cytofluorimetric analysis of the SubG1 peak evaluated by Propidium Iodide (PI) staining (upper panel) and microscopical analysis of SKBR3 cells, mock-treated or treated with Zn-curc (100 μM) for 24 h (lower panel). Percentage of apoptotic cells is shown ± SD of two independent experiments. (E) SKBR3 and U373 cells were treated with Zn-curc (100 μM) for 24 h. Equal amount of total cell extracts were subjected to immunoblot with anti-PARP (cleaved form, 87 Kd) or anti-β-actin antibodies. (F) RKO cells were treated with Zn-curc (100 μM), ZnCl2 (100 μM) or adryamicin (ADR, 2 μg/ml) for 24 h. Equal amount of total cell extracts were subjected to immunoblot with anti-γH2AX (phopho-Ser139) or anti-β-actin antibodies.