3-O-Acetyl-11-Keto-β-Boswellic Acid Suppresses Colitis-Associated Colorectal Cancer by Inhibiting the NF-Kb Signaling Pathway and Remodeling Gut Microbiota.

Objectives: Colorectal cancer (CRC) is one of the most common cancers all over the world. The progression of CRC is associated with inflammation and disruptions in intestinal flora. 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) has been noted for its potent anti-inflammatory properties. However, the effect of AKBA on colon cancer caused by inflammation and its mechanism are not unclear. The study is to explore the effect of AKBA on CRC and its mechanism.

Materials and methods: Cell proliferation, (5-ethynyl-2^'-deoxyuridine, EdU)-DNA synthesis assay and colony formation were used to assess the effect of AKBA on the proliferation of CRC cells. Flow cytometry was employed to analyze the cell cycle and apoptosis rate of cells treated with AKBA. RNA sequencing was done to explore the underlying mechanisms of AKBA. Western blot was used to assess the expression of key proteins in the nuclear factor kappa-B (NF-κB) signaling pathway after the treatment of AKBA. Real-time quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and Meso Scale Discovery (MSD) assays were employed to check the anti-inflammation effects of AKBA on Lipopolysaccharide (LPS)-induced RAW264.7 cells and LPS-induced mouse model. Additionally, the Azoxymethane/Dextran sulfate sodium (AOM/DSS)-induced colitis-associated CRC model was used to evaluate the anti-CRC effect of AKBA. Gut microbiota profiling of fecal samples from CRC mice, both with and without AKBA treatment, was conducted through metagenomic sequencing analysis.

Results: Our results showed that AKBA reduced the proliferation of HCT116 and SW620 cells, increased apoptosis of cells, and arrested the cell cycle at the G2/M phase. Results from RNA-seq showed that AKBA inhibited CRC by inhibiting the NF-κB signaling pathway and reducing cellular inflammation. Furthermore, AKBA reduced the levels of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), Interferon-γ (IFN-γ), Interleukin-IL-12p70 (IL-12p70), Interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in both the spleen and serum of LPS-induced acute inflammation mice. Additionally, AKBA inhibited the development of AOM/DSS-induced colitis-associated colon cancer in mice and positively influenced gut microbiota.

Conclusion: This study highlights the inhibitory effect of AKBA on colitis-associated CRC and reveals a novel aspect of its role in the remodeling of gut microbiota. These findings suggest that AKBA may be used as a potential therapeutic agent for CRC.