Fig. 4
From: The motility regulator flhDC drives intracellular accumulation and tumor colonization of Salmonella
Tumor colonization of Salmonella depends on intracellular accumulation in tumor masses. a) Control Salmonella (Sal) intracellularly invaded MCF7 cells more than the minimally invasive ΔsipB Salmonella (S-Sal). Green fluorescence indicates induction of GFP expression by the PSSEJ promoter, which is activated intracellularly. Scale bar is 100 μm. b) The ΔsipB mutant (S-Sal) intracellularly invaded tumor cells ten-fold less than control Salmonella in monolayer (*, P<0.05). c) The sipB knockout reduced the amount of intracellular Salmonella (green) in devices at 30 and 48 h after administration. Scale bar is 100 μm. d, e) Compared to control Sal, S-Sal (d) accumulated in tumor cells in devices 2.5 fold less (*, P<0.05, n = 6) and (e) had a four-fold slower rate of fluorescence increase (*, P<0.05). f) The sipB knockout also reduced the total density of colonized Salmonella (red) in devices at 30 and 48 h after administration. Scale bar is 100 μm. g, h) Compared to control (Sal), S-Sal (G) colonized tumors 2.5 fold less (*, P<0.05) and (h) grew in tumors four-fold slower (*, P<0.05).