Fig. 1
Inhibition of anti-apoptotic BCL-2 proteins by ABT-737 curbs WapMyc-driven mammary tumor growth. a Nuclear expression of MYC in breast cancer. Representative images from a breast cancer tissue microarray (TMA) immunostained for MYC. Samples that were missing from the TMA slide or had insufficient clinical diagnosis data, or had inadequate technical quality were excluded from all analyses. b Cross-tabulation of MYC expression against BCL-2, BCL-XL, or MCL-1 expression status. Gray boxes: Double-positive samples. c ABT-737 treatment protocol for WapMyc-induced autochthonous mammary adenocarcinoma. Red arrow: start of the treatment. d Upper: Western blot analysis of anti-apoptotic BCL-2 proteins in parallel non-tumor and tumor glands dissected from the same WapMyc mouse (N = 4 mice). Tubulin: Loading control. Lower: Immunostaining of BCL-XL in a hyperplastic gland and a tumor gland. Tumor–stroma border indicated with red dotted line. e Flow cytometric quantification of apoptosis in primary cultures. Epithelial cells were isolated from tumor or non-tumor glands, treated 24 h with 1 μM ABT-737 and stained with Annexin V/PI. Triplicate experiments performed on control (N = 2) or WapMyc tumor cell isolates (N = 5). Student’s t-test (unpaired), SD. f Quantification of apoptosis in tumor tissue. Positive cells scored from 16 vehicle and 16 ABT-737-treated tumors. Student’s t-test (unpaired), SD. g Left: Tumor growth during the 21-day treatment period. Arrow: First mice killed due to tumor burden (Ø > 2 cm). Right: Survival of the mice. h ABT-737 treatment decreases incidence of lung metastases in WapMyc tumor bearing mice, Student’s t-test (unpaired). i ABT-737 treatment protocol for orthotopically syngrafted WapMyc tumors. j MYC expression pattern in normal human breast tissue, human breast tumors, and endogenous & syngrafted WapMyc mouse mammary tumors. k Left: Tumor growth during the 21-day treatment period. Arrow: The first mice sacrificed due to tumor burden (Ø > 2 cm). Right: Survival of the mice
