Fig. 3

Basic fibroblast growth factor (bFGF) knockdown in triple-negative (TN) breast tumor cells reduces the number of chemo-residual cells and blocks subsequent colony formation. a SUM159 and BT549 cells were transfected stably with a bFGF shRNA or control (ctrl) shRNA. The knockdown of nuclear bFGF was confirmed by immunoblotting equivalent amounts of nuclear extract with bFGF antibody. Protein loading was accessed using Lamin A antibody. Protein bands were quantified using Image J software (NIH), and the relative ratio of bFGF to loading control is shown for each lane. b and c SUM159 cells (b) and BT549 cells (c) transfected stably with a bFGF shRNA or control shRNA were treated with doxorubicin as described in Fig. 1a. Upper panel: pictures of remaining chemo-residual cells were taken on day 7. Magnification ×20. Lower panel: numbers of chemotherapy (chemo)-enriched chemo-residual cells on day 7 were determined by trypan blue exclusion; n = 3, error bars represent SD, ***p <0.001, two-tailed Student’s t test. d and e SUM159 cells (d) and BT549 cells (e) transfected stably with a bFGF shRNA or control (ctrl) shRNA were treated with doxorubicin as described in Fig. 1a. Upper panel: colonies (containing >50 cells) were quantified on the indicated days. Error bars represent SD, n = 3, **p <0.01, ***p <0.001, two-tailed Student’s t test. Lower panel: colonies were fixed and stained with crystal violet on day 22 (SUM159 cell) and day 24 (BT549 cell). Similar results were obtained in at least three independent trials