Figure 4.
In vitro and in vivo growth of HT-1080 clones stably transfected with sflt-1 cDNA. HT-1080 tumor cells were stably transfected with control pcDNA3 plasmid (open square) or the corresponding pCIsflt-1 plasmid incorporating HCMV intron A (pCIsflt-1) from which clones C4 (open circles) and B3 (filled circles) were selected. (A) In vitro the control (pcDNA3), moderate (C4) sFLT-1-expressing, and high (B3) sFLT-1-expressing clones grew with equivalent rates in culture. (B) In nude mice (n = 6/group) tumors developing from two s.c. injections totaling 3 × 106 cells/animal of either the control (pcDNA3), moderate sFLT-1-expressing (C4), or high (B3) sFLT-1 expressing clones grew at high, intermediate, and low rates, respectively. (C) Tumors are shown in situ 19 days after injections of HT-1080 cells either stably transfected with control plasmid DNA (pcDNA3, top) or clones stably expressing intermediate (C4, middle) and high (B3, bottom) levels of sFLT-1.