Suppressed oncogenic molecules involved in the treatment of colorectal cancer by fecal microbiota transplantation

Abstract

Dysbiosis of the intestinal microbiota is prevalent among patients with colorectal cancer (CRC). This study aims to explore the anticancer roles of the fecal microbiota in inhibiting the progression of colorectal cancer and possible mechanisms. The intestinal microbial dysbiosis in CRC mice was significantly ameliorated by fecal microbiota transplantation (FMT), as indicated by the restored ACE index and Shannon index. The diameter and number of cancerous foci were significantly decreased in CRC mice treated with FMT, along with the restoration of the intestinal mucosal structure and the lessening of the gland arrangement disorder. Key factors in oxidative stress (TXN1, TXNRD1, and HIF-1α); cell cycle regulators (IGF-1, BIRC5, CDK8, HDAC2, EGFR, and CTSL); and a critical transcription factor of the innate immune signal pathway (IRF5) were among the repressed oncogenic targets engaged in the FMT treatment of CRC. Correlation analysis revealed that their expressions were positively correlated with uncultured_bacterium_o_Mollicutes_RF39, Rikenellaceae_RC9_gut_group, and negatively correlated with Bacillus, Marvinbryantia, Roseburia, Angelakisella, Enterorhabdus, Bacteroides, Muribaculum, and genera of uncultured_bacterium_f_Eggerthellaceae, uncultured_bacterium_f_Xanthobacteraceae, Prevotellaceae_UCG-001, uncultured_bacterium_f_Erysipelotrichaceae, uncul-tured_bacterium_f_Lachnospiraceae, uncultured_bacterium_f_Ruminococcaceae, Eubacterium_coprostanoligenes_group, Ruminococcaceae_UCG-005, and uncultured_bacterium_f_Peptococcaceae. This study provides more evidence for the application of FMT in the clinical treatment of CRC.

Keywords: colorectal cancer; fecal microbiota transplantation; intestinal homeostasis; intestinal microbiota; oncogenic molecules.

Figure 1

Inhibitory effect of FMT on CRC progression. (A) Design of the experiment. (B) Pictures of intestinal tissue. Ctl, normal control mice; CRC, colorectal cancer mice; FMT, colorectal cancer mice receiving fecal microbiota transplantation. (C,D) The average number and diameter of cancerous foci. ^**p < 0.01 (Ctl, n = 6; CRC, n = 6; FMT, n = 6). (E) The average body weight of mice in each week. ^*p < 0.05 (Ctl, n = 19; CRC, n = 15; FMT, n = 18). (F) HE staining of intestinal tissue. (G) Immuno-histochemical staining of Ki67 and cleaved caspase-3 in intestinal tissue. ^*p < 0.05, n = 6.

Figure 2

FMT reverses the microbial disturbance in CRC mice. (A–D) The distribution of gut microbiota at the levels of phylum, family, genus and species. (E,F) Alpha diversity indicated by Shannon index (E) and ACE index (F), ^*p < 0.05 and ^***p < 0.001, n = 6. (G,H) Beta diversity indicated by PCoA analysis (G) and NMDS analysis (H). (I) Cluster analysis of samples. (J) Bacterial co-occurrence network.

Figure 3

FMT inhibits the expression levels of cancer-promoting molecules. (A) Differentially expressed genes associated with CRC development. (B) Protein levels of the cancer-promoting molecules detected by western blot. ^*p < 0.05, n = 3. (C) The abundance of intestinal microbes related to the cancer-promoting factors. ^*p < 0.05, Ctl vs. CRC; ^#p < 0.05, CRC vs. FMT, n = 3. (D) Correlation analysis between the intestinal bacteria and the molecules screened out. ^*p < 0.05 and ^**p < 0.01, n = 3.

Figure 4

Locations of the oncogenic targets in the intestinal tissue. BIRC5, TXN1, TXNRD1, CDK8, HIF-1α, IGF-1, HDAC2, CTSL, IRF5, and EGFR were distributed in all sub-structures of the mucosa, including the mucosal epithelium, amina propria, and muscularis mucosae.