Figure 7. Transient MT3-MMP expression in the MT3-MMP knockdown cells rescues nodular-type growth in collagen in conjunction with increased fibrin invasion.

(A) MT3-MMP was detected by immunoblotting in COS-1 cells transiently expressing mock vector (Mock), MT3-MMP (MT3), or rescue constructs rescMT3-1 and rescMT3-2. Ponceau staining served as a loading control. Asterix marks non-specific bands. (B) WM852 cells stably expressing MT3-MMP targeting shRNA (shMT3-2) transfected to express MT3-MMP rescue vectors (rescMT3-1 and rescMT3-2) or mock vector were embedded in 3D collagen type I and fibrin gels. Chart shows relative percentage of invasive colonies formed after 5 d, n = 3. (C) Fluorescent micrographs show representative colonies stained for F-actin (red) to visualize the cells. (D) WM852 cell pools after lentiviral expression of scrambled shRNA (Scr) and shMT3-2 as well as knockdown cells transfected with MT3-MMP rescue vectors (rescMT3-1 and rescMT3-2) were allowed to invade into collagen type I gels for 7 d followed by imaging and quantification, n = 3.