Fig. 4

Transfection of basic fibroblast growth factor (bFGF) knockdown cells with 23-kDa bFGF (nuclear bFGF) vector restores chemo-residual cell survival and subsequent colony formation. a bFGF shRNA-transfected SUM159 cells were transfected with vectors expressing low molecular weight (LMW) (cytosolic) bFGF, high molecular weight (HMW) (nuclear) bFGF, or pCI as a vector control (ctrl). The expression of addback constructs in stable transfectants was confirmed and compared to control shRNA-transfected cells by immunoblotting equivalent amounts of nuclear (upper two lanes) or cytosolic (lower two lanes) extract with bFGF antibody. Protein loading was assessed using Lamin A or GAPDH antibody. b SUM159 cells expressing control shRNA, bFGF shRNA, or bFGF shRNA plus indicated addback constructs were treated with doxorubicin as described in Fig. 1a. The number of chemo-residual cells was determined on day 7 by trypan blue exclusion. Error bars represent SD, n = 3, ***p <0.001, two-tailed Student’s t test. c Colonies (containing >50 cells) were quantified on the indicated days. Error bars represent SD, n = 3, ***p <0.001, two-tailed Student’s t test. d Colonies were fixed and stained with crystal violet on day 20. Similar results were obtained in at least three independent trials