Anti-tumour effect of Huangqin Decoction on colorectal cancer mice through microbial butyrate mediated PI3K/Akt pathway suppression

Introduction. Huangqin Decoction (HQD), a Chinese herbal formula, is widely used for various diseases, including colorectal cancer (CRC). Hypothesis/Gap Statement. We proposed that microbial butyrate mediated PI3K/Akt pathway suppression might involve the anti-cancer effect of HQD. Aim. This study aimed to evaluate the potential mechanism of HQD against CRC. Methodology. An azoxymethane plus dextran sulphate sodium induced CRC mouse model was used, and the intestinal flora and faecal short-chain fatty acid changes were detected, respectively, after HQD administration with 16S rRNA sequencing and gas chromatography coupled with mass spectrometry. Disease activity index, colon length and levels of inflammatory cytokines were measured to evaluate the effect of HQD on intestinal inflammation. Tumour size, number and histopathology were assessed to reflect the impact of HQD on tumour burden. Apoptosis and PI3K/Akt pathway activity were measured by TUNEL staining and Western-blotting. In vitro, the effects of sodium butyrate (NaB) on the viability of CRC cell lines were detected by the Cell-counting Kit-8. The apoptotic cells were determined by TUNEL staining. Cell migration and invasion were assessed by wound healing assay and Transwell assay, respectively. Western-blotting and immunofluorescent staining were used to test the activity of PI3K/Akt pathway. Results. Animal study showed that HQD could improve the gut dysbiosis, increase the abundance of Clostridium and the level of faecal butyric acid. Then, we found that HQD could attenuate colitis, reduce tumour burden, promote cell apoptosis and suppress PI3K/Akt pathway activity in CRC mice. In vitro experiment revealed that NaB treatment could inhibit cell growth, migration and invasion in CRC cell lines. Additionally, NaB enhanced cellular apoptosis, and reduced phosphorylated PI3K and Akt expressions. Interestingly, addition of 740Y-P, an agonist of PI3K, reversed the NaB effects on CRC cells. Conclusion. Overall, in this study, we revealed that HQD could induce apoptosis through microbial butyrate mediated PI3K/Akt inhibition and perform anti-CRC activity.