Ethanol promotes alcohol-related colorectal cancer metastasis via the TGF-β/RUNX3/Snail axis by inducing TGF-β1 upregulation and RUNX3 cytoplasmic mislocalization

Background: Alcohol intake is a well-known lifestyle risk factor for CRC, and an increasing number of studies have revealed that alcohol intake is also tightly associated with CRC metastasis. However, the effect of alcohol on CRC metastasis and its underlying mechanism remain unclear. Methods: A retrospective cohort study was performed to investigate the characteristics of patients with alcohol-related CRC. The effects of ethanol on the biological behaviours of CRC cells were assessed through in vivo and in vitro assays using the Lieber-DeCarli ethanol liquid diet and ethanol, respectively. The ethanol-mediated signalling pathway and downstream factors were screened through ELISA, western blot, immunofluorescence and co-immunoprecipitation. Findings: Most patients with alcohol-related CRC, particularly those with tumour metastasis, were characterized by a notably higher circulating ethanol level and a lower systemic acetaldehyde level. Moreover, CRC cells accumulated in ethanol, but not acetaldehyde, to notably higher levels compared with adjacent normal cells. Alcohol intake significantly promoted CRC metastasis via the ethanol-mediated TGF-β/Smad/Snail axis, and ethanol induced the cytoplasmic mislocalization of RUNX3 and further promoted the aggressiveness of CRC by targeting Snail. Pirfenidone (PFD) significantly eliminated the effects of ethanol on CRC metastasis by specifically blocking TGF-β signalling. Interpretation: Alcohol intake plays a vital role in CRC metastasis via the ethanol-mediated TGF-β/RUNX3/Snail axis, and PFD might be a novel therapeutic management strategy for CRC.