Figure 6.

Putrescine lowers the growth of a pks+ E. coli strain isolated from a patient with colorectal cancer. A, Representative images of methylene blue staining of megalocytosis of HT-29 cells by E. coli moCRC10 at 4 hours postinfection (magnification 200×). EcNC101 ΔclbP and WT were used as pks− and pks+ control strains, respectively. Quantification of megalocytosis of HT-29 cells. (Upper gray dash line is control values; lower red dash line is EcNC101 values; mean ± SEM, ANOVA post hoc Dunnett compared with control; N = 3.) B, Scan of in-cell Western image showing DNA DSBs with merged detection of total DNA (red, 680 nm) and γ-H2AX (green, 800 nm). γ-H2AX fold induction (analysis was done on the single-colored picture; mean ± SEM, ANOVA post hoc Dunnett compared with control; N = 3). C,E. coli moCRC10 was grown in the absence or presence of putrescine (mean ± SEM, repeated-measure t test; N = 5). D, Lcn-2 concentration in fecal samples from healthy controls and patients with colorectal cancer. E, Abundance of Gram-negative lactose-fermenting strains from the Escherichia, Enterobacteria, and Klebsiella genera [t test on log(Y)-transformed data]. F, Scatterplot of the association between Lcn-2 and Enterobacteriaceae; N = 22 healthy individuals/N = 38 patients with colorectal cancer. n.s., nonsignificant; *, P < 0.05; **, P < 0.01; ***, P < 0.001.