Figure 4

Role of survivin family proteins in doxorubicin resistance in breast cancer. (A) Human breast tumors with low (Ki-67 ≤ 15%) or high (Ki-67 > 15%) proliferative index were analyzed for differential expression of survivin-ΔEx3 by qPCR. *P = 0.03. (B, C) MCF-7 cells were transfected with survivin-ΔEx3 (SVV-ΔEx3) or control vector (Ctrl), treated with 1 μM doxorubicin or vehicle, and analyzed for cell viability (B) or apoptosis (C) after 48 h by an 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) or terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, respectively. *P = 0.01; **P = 0.002 (unpaired t test).