Extracellular Superoxide Production by Enterococcus faecalis Promotes Chromosomal Instability in Mammalian Cells  Xingmin Wang, Mark M. Huycke  Gastroenterology  Volume 132, Issue 2, Pages 551-561 (February 2007) DOI: 10.1053/j.gastro.2006.11.040 Copyright © 2007 AGA Institute Terms and Conditions

Figure 1 E faecalis causes CIN in target cells. (A) Survival curve for ALN cells exposed to increasing doses of OG1RF at 37°C for 2 hours. (B) Survival curve for ALN cells exposed to increasing doses of γ-irradiation. (C) A dose–response in mutant fraction was noted for ALN cells exposed to OG1RF at 37°C for 2 hours. (D) The mutant fraction for ALN cells also increased with radiation dose (R2 = 0.99). Mutant fraction produced by OG1RF at 1 × 109 cfu mL−1 was equivalent 2 Gy γ irradiation (hashed lines). Mutant fractions were calculated as the number of surviving colonies divided by the total number of cells plated after correction for plating efficiency. Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 2 CIN in ALN cells. (A) Multiplex PCR verified deletions of CD59 exons for 8 of 10 randomly selected colonies. The 4 CD59 exons (arrows) were present in an ALN control colony and for 2 colonies that survived complement lysis (C3 and C26). No amplicons were generated for any CD59 exon in 8 of 10 surviving colonies (C6, C11, C21–C25, and C27). (B) Using human SNP mapping, clones negative by multiplex PCR for CD59 exons showed large deletions in chromosome 11 (12 to 110 Mb) in 4 clones (C6, C11, C23, and C27) and smaller deletions in 4 other clones (C21, C22, C24, and C25). CD59 is located at 11p13 (arrow) and signal shift to the left of baseline represents loss of SNPs. Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 3 Commensal E coli does not promote CIN. (A) Survival curve for ALN cells exposed to increasing doses of DH5α at 37°C for 2 hours. (B) No significant difference in mutant fraction was noted for ALN cells exposed to DH5α at 37°C for 2 hours compared to the no bacteria control. Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 4 CIN in ALN cells is due to extracellular ·O2− from E faecalis and COX-2. (A) Mutant fraction for ALN cells exposed to OG1RF (109 cfu mL−1) decreased 50% with MnSOD, but not catalase. (B) Mutant fraction increased with arachidonic acid but not docosahexaenoic acid (left) and decreased with αT, γT, and γ-CEHC (right). (C) OG1RF induced Cox-2 mRNA in ALN cells (upper); Cox-2 mRNA was decreased by MnSOD (middle); E coli DH5α did not induce Cox-2 expression (lower). (D) Mutant fractions decreased following treatment with COX-2 inhibitors (**P < .01, ***P < .001, NS, not significant; P values in comparison to OG1RF). Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 5 Phagocytosis of E faecalis or E coli by macrophages causes CIN in ALN cells. (A) Murine macrophages (RAW264.7 cells) exposed to OG1RF were cultured on insert in upper compartment of a dual-chamber model with ALN cells in lower compartment as the target. (B) OG1RF- or DH5α-treated RAW264.7 cells induced CIN in ALN cells at MOIs >1 (*P < .05, **P < .01, ***P < .001, NS, not significant; P values in comparison to no bacteria control); similarly, DH5α-treated RAW264.7 cells modestly increased CIN in ALN cells, but not at an MOI of 1000 (*P < .05, **P < 0.01, ***P < .001, NS, not significant; P values in comparison to no bacteria control; black bar, OG1RF; open bar, DH5α). (C) OG1RF treatment of RAW264.7 cells up-regulated COX-2; RT-PCR (upper) and Western blotting (lower). (D) OG1RF caused dose-dependent expression of COX-2 in RAW264.7 cells; RT-PCR (upper) and Western blotting (lower); (E) DH5α also caused COX-2 expression; RT-PCR (upper) and Western blotting (lower); RNA extracted at 24 hours and protein at 48 hours. Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 6 CIN in ALN cells is caused by E faecalis-induced COX-2 expression in macrophages in dual-chamber model. (A) ALN mutant fractions decreased when OG1RF-treated RAW264.7 cells were pretreated with COX-2 inhibitors or Cox-2 silenced by siRNA (***P < .001; P values in comparison to an MOI of 1000). (B) COX-2 knock-down verified by RT-PCR (left) and Western blotting (right). Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions

Figure 7 Extracellular ·O2− from E faecalis promotes COX-2 expression in macrophages and induces CIN in ALN cells in the dual-chamber model. (A) ALN cell mutant fraction using heat-inactivated OG1RF or MnSOD (upper; *P < .05, **P < .01, ***P < .001; P values in comparison to OG1RF). COX-2 expression by Western blotting (middle) and normalized to β-actin control (lower). (B) γT (200 μmol/L) and γ-CEHC (100 μmol/L), but not αT (200 μmol/L), protect ALN cells from CIN (upper; **P < .01, ***P < .001, NS, not significant; P values in comparison to OG1RF). COX-2 expression decreased by γT, but not αT or γ-CEHC. COX-2 protein by Western blotting (middle) and normalized to β-actin control (lower). Gastroenterology 2007 132, 551-561DOI: (10.1053/j.gastro.2006.11.040) Copyright © 2007 AGA Institute Terms and Conditions