Gelsolin Induces Cancer Invasion via uPA Cascade Figure 3. Gelsolin promotes migration and invasion of colorectal cancer cells. (A) Endogenous gelsolin level was increased in an in vivo- derived metastatic variant of HCT116, E1, which was described in [31]. (B) Gelsolin overexpression plasmid was constructed by cloning human cytoplasmic gelsolin cDNA into pIRES2-EGFP vector (left). HCT116 cells were either transfected with gelsolin-pIRES2-EGFP plasmid or empty pIRES2- EGFP plasmid to establish stable gelsolin-overexpressing cell lines and vector control cell lines respectively. Western blot analysis confirmed increased gelsolin expression in HCT116 cell lines stably-transfected with the gelsolin-overexpression plasmid compared to those transfected with control plasmid. (C) Western blot showing transient gelsolin siRNA knockdown (KD) at 3 days in wild-type HCT116 and gelsolin-overexpressing HCT116 cells, E1, as well as other colorectal cancer cell lines DLD-1 and Caco-2 cells. Control cells (Cont) were treated with control siRNA. (D) Increased gelsolin in HCT116 enhanced tumor cell migration and invasion. The migration of gelsolin-overexpressing HCT116 cells through uncoated transwells and PLOS ONE | www.plosone.org 5 August 2012 | Volume 7 | Issue 8 | e43594