2c). Neither wt Ia protein nor the nonrelative LWMP could
kill MCF-7, Zr-75-30 and Raji cells up to the maximal tested concentration at any time points (125 μg/ml). 72 hours co-incubation of Zr-75-30 and Raji with Fab-Ia, Sc-Ia, PMN and LWMP peptide molecules at any concentration did not significantly affect the viability of these cells relative to untreated control (Fig. 2a). Figure 2 In vitro killing see more activity assays of PMN. (a) Killing effects of PBS, non-relative LWMP, wt Ia, Fab-Ia, PMN and Sc-Ia on MCF-7, Zr-75-30 and Raji cells lines. LWMP, low molecular weight marker protein; wt Ia, wild-type colicin Ia; Fab-Ia, Fab segment from original antibody-colicin Ia fusion peptide; PMN, protomimecin; Sc-Ia, ScFv segment this website from original antibody-colicin Ia fusion peptide. (b) MCF-7 breast cancer click here cells were incubated with 75 μg/ml PMN for 24, 48 and 72 hrs, respectively. And tumor cells were stained with acridine orange (green color) and propidium iodide (red color). Red
spots, dead cell mass; Green spots, live cell. After co-incubation for 72 hrs, approximately 80% of all MCF-7 cells had died (upper panel). T, PMN-treated group; C, control group treated with PBS. (c) Cytotoxicity of different concentration of PMN against MCF-7. We assessed the antigen-recognition capabilities of PMN, Fab, Sc-Fv, LWMP and wt Ia peptides against MCF-7 cell by competition with the parent antibody. The results indicated that the VHFR1C-10-VHCDR1-VHFR2-VLCDR3-VLFR4N-10 mimetic had nearly the same extent effect on blocking binding of the parent antibody as Fab and Sc-Fv peptides (Fig. 3a). The concentration of the mimetic peptides that could induce 50% saturation of antigen was about 10~15% that of OAbs (Fig. 3b). The killing activity of PMN molecules against MCF-7 cells could be inhibited up to 90% by increasing concentrations of OAbs or synthetic VHFR1C-10-VHCDR1-VHFR2-VLCDR3-VLFR4N-10
mimetic molecules (Fig. 3c, d). Figure 3 The competition ability of synthetic V H FR1 C-10 -V H CDR1-V H FR2-V L CDR3-V L FR4 N-10 . (a) Fixed MCF-7 cells were incubated Protein tyrosine phosphatase with PBS, LWMP, Fab, PMN and Sc-Fv peptides (50 μM) and DAPI (50 ng/ml) prior to flow cytometry. LWMP, low molecular weight marker protein; Fab, Fab segment from original antibody; PMN, protomimecin; Sc-Fv, ScFv segment from original antibody. (b) The relative affinity of VHFR1C-10-VHCDR1-VHFR2-VLCDR3-VLFR4N-10 peptides and OAbs to antigen. OAb, original antibody. (c) Concentration-dependent inhibition of different concentration of synthetic mimetic antibody or OAb against 75 μg/ml PMN. (d) MCF-7 cell survival ratio of the inhibition activity of OAb against PMN (75 μg/ml). OAb, original mAb antibody A520C9. In vivo activity and the biodistribution of PMN PMN, Fab-Ia and Sc-Ia agents were administered to tumor-bearing BALB/c nude mice at 1,200 μg/mouse/day (400 μg/8 hours, i.p. tid).