Colitis-associated Colorectal Cancer Mouse Research Articles

Colon-targeted S100A8/A9-specific peptide systems ameliorate colitis and colitis-associated colorectal cancer in mouse models.

The link between chronic inflammation and cancer development is well acknowledged. Inflammatory bowel disease including ulcerative colitis and Crohn's disease frequently promotes colon cancer development. Thus, control of intestinal inflammation is a therapeutic strategy to prevent and manage colitis-associated colorectal cancer (CRC). Recently, gut mucosal damage-associated molecular patterns S100A8 and S100A9, acting via interactions with their pattern recognition receptors (PRRs), especially TLR4 and RAGE, have emerged as key players in the pathogenesis of colonic inflammation. We found elevated serum levels of S100A8 and S100A9 in both colitis and colitis-associated CRC mouse models along with significant increases in their binding with PRR, TLR4, and RAGE. In this study we developed a dual PRR-inhibiting peptide system (rCT-S100A8/A9) that consisted of TLR4- and RAGE-inhibiting motifs derived from S100A8 and S100A9, and conjugated with a CT peptide (TWYKIAFQRNRK) for colon-specific delivery. In human monocyte THP-1 and mouse BMDMs, S100A8/A9-derived peptide comprising TLR4- and RAGE-interacting motif (0.01, 0.1, 1 μM) dose-dependently inhibited the binding of S100 to TLR4 or RAGE, and effectively inhibited NLRP3 inflammasome activation. We demonstrated that rCT-S100A8/A9 had appropriate drug-like properties including in vitro stabilities and PK properties as well as pharmacological activities. In mouse models of DSS-induced acute and chronic colitis, injection of rCT-S100A8/A9 (50 μg·kg-1·d-1, i.p. for certain consecutive days) significantly increased the survival rates and alleviated the pathological injuries of the colon. In AOM/DSS-induced colitis-associated colorectal cancer (CAC) mouse model, injection of rCT-S100A8/A9 (50 μg·kg-1·d-1, i.p.) increased the body weight, decreased tumor burden in the distal colon, and significantly alleviated histological colonic damage. In mice bearing oxaliplatin-resistant CRC xenografts, injection of rCT-S100A8/A9 (20 μg/kg, i.p., every 3 days for 24-30 days) significantly inhibited the tumor growth with reduced EMT-associated markers in tumor tissues. Our results demonstrate that targeting the S100-PRR axis improves colonic inflammation and thus highlight this axis as a potential therapeutic target for colitis and CRC.

Colitis Induces Sex-Specific Intestinal Transcriptomic Responses in Mice.

There are significant sex differences in colorectal cancer (CRC), including in incidence, onset, and molecular characteristics. Further, while inflammatory bowel disease (IBD) is a risk factor for CRC in both sexes, men with IBD have a 60% higher risk of developing CRC compared to women. In this study, we investigated sex differences during colitis-associated CRC (CAC) using a chemically induced CAC mouse model. The mice were treated with azoxymethane (AOM) and dextran sodium sulfate (DSS) and followed for 9 and 15 weeks. We performed RNA-sequencing of colon samples from males (n = 15) and females (n = 15) to study different stages of inflammation and identify corresponding transcriptomic sex differences in non-tumor colon tissue. We found a significant transcriptome response to AOM/DSS treatment in both sexes, including in pathways related to inflammation and cell proliferation. Notably, we found a stronger response in males and that male-specific differentially expressed genes were involved in NFκB signaling and circadian rhythm. Further, an overrepresented proportion of male-specific gene regulations were predicted to be targets of Stat3, whereas for females, targets of the glucocorticoid receptor (Gr/Nr3c1) were overrepresented. At 15 weeks, the most apparent sex difference involved genes with functions in T cell proliferation, followed by the regulation of demethylases. The majority of sex differences were thus related to inflammation and the immune system. Our novel data, profiling the transcriptomic response to chemically induced colitis and CAC, indicate clear sex differences in CRC initiation and progression.

TLR9 induces colitis-associated colorectal carcinogenesis by regulating NF-κB expression levels.

Chronic colorectal inflammation has been associated with colorectal cancer (CRC); however, its exact molecular mechanisms remain unclear. The present study aimed to investigate the effect of Toll-like receptor 9 (TLR9) on the development of colitis-associated CRC (CAC) through its regulation of the NF-κB signaling pathway. By using a CAC mouse model and immunohistochemistry, the present study discovered that the protein expression levels of TLR9 were gradually upregulated during the development of CRC. In addition, the expression levels of TLR9 were revealed to be positively correlated with NF-κB and Ki67 expression levels. In vitro, inhibiting TLR9 expression levels using chloroquine decreased the cell viability, proliferation and migration of the CRC cell line HT29, and further experiments indicated that this may occur through downregulating the expression levels of NF-κB, proliferating cell nuclear antigen and Bcl-xl. In conclusion, the findings of the present study suggested that TLR9 may serve an important role in the development of CAC by regulating NF-κB signaling.

Administration of Bifidobacterium bifidum CGMCC 15068 modulates gut microbiota and metabolome in azoxymethane (AOM)/dextran sulphate sodium (DSS)-induced colitis-associated colon cancer (CAC) in mice.

The gut microbiota plays an important role in colorectal cancer (CRC), and the use of probiotics might be a promising intervention method. The aim of our study was to investigate the beneficial effect of Bifidobacterium bifidum CGMCC 15068 on an azoxymethane (AOM)/dextran sulphate sodium (DSS)-induced colitis-associated CRC (CAC) mouse model. CAC was induced by an intra-peritoneal injection of AOM (10mg/kg) and three 7-day cycles of 2% DSS in drinking water with a 14-day recovery period between two consecutive DSS administrations. B. bifidum CGMCC 15068 (3 × 109CFU/mL) was gavaged once daily during the recovery period. Then, the faecal microbial composition and metabolome were profiled using the 16S rRNA sequencing technology and gas chromatography-mass spectrometry (GC-MS), respectively. The administration of B. bifidum CGMCC 15068 attenuated tumourigenesis in the CAC mouse model. In addition, B. bifidum CGMCC 15068 pre-treatment increased the relative abundance of Akkermansia, Desulfovibrionaceae, Romboutsia, Turicibacter, Verrucomicrobiaceae, Ruminococcaceae_UCG_013, Lachnospiraceae_UCG_004, and Lactobacillus. Meanwhile, B. bifidum CGMCC 15068 altered metabolites involved in the citrate cycle (TCA cycle), glycolysis, butyrate metabolism, fatty acid biosynthesis, and galactose metabolism. Several significant correlations were identified between the differentially abundant microbes and metabolites. These findings supported the beneficial role of B. bifidum CGMCC 15068 in intestinal health by modulating dysbiosis and the gut metabolic profile. The manipulation of the gut microbial composition using probiotics might be a promising prevention strategy for CRC. Long-term and large-scale clinical trials are warranted for the potential clinical applications of this strategy in the future.

Interleukin-6 stimulates aerobic glycolysis by regulating PFKFB3 at early stage of colorectal cancer.

Chronic inflammation is a well-known etiological factor for colorectal cancer (CRC) and cancer cells are known to preferentially metabolize glucose through aerobic glycolysis. However, the connection between chronic inflammation and aerobic glycolysis in the development of CRC is largely unexplored. The present study investigated whether interleukin-6 (IL-6), a pro-inflammatory cytokine, promotes the development of CRC by regulating the aerobic glycolysis and the underlying molecular mechanisms. In colitis-associated CRC mouse, anti-IL-6 receptor antibody treatment reduced the incidence of CRC and decreased the expression of key genes in aerobic glycolysis, whereas the plasma concentrations of glucose and lactate were not affected. Consistently, IL-6 treatment stimulated aerobic glycolysis, upregulated key genes in aerobic glycolysis and promoted cell proliferation and migration in SW480 and SW1116 CRC cells. 6-phoshofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) was the most downregulated gene by anti-IL-6 receptor antibody in colorectal adenoma tissues. Further analysis in human samples revealed overexpression of PFKFB3 in colorectal adenoma and adenocarcinoma tissues, which was also associated with lymph node metastasis, intravascular cancer embolus and TNM stage. In addition, the effect of IL-6 on CRC cells can be abolished by knocking down PRKFB3 through siRNA transfection. Our data suggest that chronic inflammation promotes the development of CRC by stimulating aerobic glycolysis and IL-6 is functioning, at least partly, through regulating PFKFB3 at early stage of CRC.

Low Molecular Weight Apple Polysaccharides Induced Cell Cycle Arrest in Colorectal Tumor

Dietary components play an important role in cancer prevention. Many ingredients from apples have been proven to have antitumor potency. We thus made low molecular weight apple polysaccharides (LMWAP) and evaluated the effects of it on colorectal cancer (CRC). The effects of LMWAP on human colon carcinoma cells (HT-29) were evaluated using a microarray. Then, cell-cycle distribution was measured by flow cytometric analysis. A colitis-associated colorectal cancer mouse model was used to assess the effect of LMWAP on in vivo CRC prevention. Treatment of HT-29 cells with LMWAP resulted in 333 genes expression over cutoff values (≥2-fold). Further analysis demonstrated that pathways of cell cycle were mainly influenced. At the concentrations from 0.001 to 0.1 mg/mL, LMWAP induced a G0/G1 phase block in HT-29 cells in a dose-dependent way. In vivo studies revealed that administration of LMWAP could protect ICR mice against CRC effectively. The results of Western blot suggested LMWAP induced cell-cycle arrest in a p53 independent manner. These data indicate that LMWAP could inhibit the development of CRC through affecting cell cycle, and it has potential for clinical prevention for colon cancer.