Barnase as a New Therapeutic Agent Triggering Apoptosis in Human Cancer Cells
Figure 2
Binding of barnase and scFv 4D5-dibarnase to cells.
The cell-binding ability of the recombinant proteins demonstrated by fluorescent microscopy. Cells were incubated at 4°C for 1 h with either 20 nM scFv 4D5-dibarnase (A, B and D), or a mixture of 20 nM scFv 4D5-dibarnase and 20 nM scFv 4D5 (C), or 20 µM barnase (E). Unbound proteins were removed, and then living (A–D) or fixed (E) cells were stained with rabbit anti-barnase antiserum and GAR-TR as described in Materials and Methods. The scFv 4D5-dibarnase bound to HER2-positive SKOV-3 cells (A and B), this specific binding was inhibited by scFv 4D5 (C). The scFv 4D5-dibarnase did not bind to HER2-negative CTLL-2 cells (D). Cytoplasmic staining of SKOV-3 cells with 20 µM barnase was observed (E). Magnification, 400×.