Fig. 4: Gut microbes mediate tumor promotion of FADS1 in CRC.

a An orthotopic tumor model of CRC was established by injecting SW480^Luc cells or HCT116^Luc cells into the wall of the cecum of BALB/C null mice. b Computed tomography (CT) with 3D organ reconstruction bioluminescence imaging of the orthotopic tumor of BALB/C null mice injected with shNC and shFADS1 SW480^Luc cells (n = 6 mice per group, means ± s.d.; two-tailed unpaired t test). Gut microbes were deleted by quadruple antibiotics for two weeks. The yellow signal represents intestine, the green signal represents colon and the red signal represents tumor. Scale colour bar: 1×10⁶−1.00×10⁷. **p = 0.007. c CT with 3D organ reconstruction bioluminescence imaging of orthotopic tumors in BALB/C null mice injected with shNC and shFADS1 HCT116^Luc cells (n = 6 mice per group, means ± s.d.; two-tailed unpaired t test). Gut microbes were deleted by quadruple antibiotics for two weeks. The yellow signal represents intestine, the green signal represents colon and the red signal represents tumor. Scale colour bar: 1×10⁶−1.00×10⁷. **p = 0.004. d Ratio of gram-negative and gram-positive bacteria in the orthotopic tumors of BALB/C null mice injected with shNC and shFADS1 cells (n = 6 mice per group, Chi square test, n = 3 technical replicates). *p = 0.037, 0.031. e Relative abundance of Es. coli, En. faecalis and Lactobacillus in the orthotopic tumor injected with shNC and shFADS1 cells (n = 6 mice per group, Box plots: Min to Max; two-tailed unpaired t test). **p = 0.008, 0.009, 0.005, 0.002, 0.004, 0.005. f IVIS imaging of the orthotopic tumor in the cecum of BALB/C null mice injected with shNC and shFADS1 SW480^Luc cells (n = 6 mice per group, means ± s.d.; two-tailed unpaired t test), gut microbes were selectively deleted by 0.2 g/L aztreonam or 0.1 g/L vancomycin treatment for two weeks. Scale colour bar: 3.96×10⁷−1.55×10⁸. ***p < 0.001, ns indicates no statistical significance. Source data are provided in the Source Data file.