Brevilin A suppresses lipid metabolism reprogramming in colorectal adenoma-to-adenocarcinoma sequence via the NR1D1/APOH signaling axis.

[BACKGROUND] The adenoma-carcinoma sequence is a classic pathway for colorectal cancer (CRC) occurrence, and this pathway is associated with lipid metabolism reprogramming. Brevilin A (Br), an extract from Centipeda minima, exhibits anticancer effects in multiple tumors. However, its role in inhibiting the adenoma-carcinoma sequence remain unclear.

[METHODS] Using APC mice on a high-fat diet, APC-knockout mouse models, and in vitro cell assays, we investigated Br's effects, combining 16S rRNA sequencing, fecal metabolite profiling, and proteomics to analyze lipid metabolism-related factors. Chromatin immunoprecipitation (ChIP), co-immunoprecipitation (co-IP) and Surface Plasmon Resonance (SPR) were employed to investigate Nuclear receptor subfamily 1 group D member 1 (NR1D1) binding to the Apolipoprotein H (APOH) promoter and Br-mediated ubiquitination of NR1D1.

[RESULTS] Specifically, in APC mice fed a high-fat diet, APC-knockout mouse and nude-mice model, Br administration led to marked reductions in tumor number and volume, as evidenced by gross intestinal observation and HE staining. Meanwhile, Oil Red O staining of colonic and tumor tissues showed that Br decreased lipid deposition, confirming its role in mitigating lipid accumulation during tumor progression. In vitro, Br suppressed CRC cells and adenoma organoids proliferation, accompanied by downregulation of proliferation markers including PCNA and c-Myc. Mechanistically, Br directly bound to NR1D1, inhibiting K48- and K11-linked ubiquitination at its K124/K171 residues. This ubiquitination, dependent on E3 ligase TRIM21, stabilized NR1D1 and reduced its proteasomal degradation. Reduced NR1D1 after treatment of Br lost transcriptional repression of APOH, promoting APOH expression, validated by ChIP assay showing NR1D1 binding to the APOH promoter. Silencing APOH abrogated Br's antitumor effects, while APOH deficiency exacerbated lipid deposition and elevated triglyceride levels. Clinically, APOH expression was downregulated in CRC tissues and correlated with favorable prognosis, whereas NR1D1 exhibited the opposite trend.

[CONCLUSIONS] Br suppresses CRC progression via regulating lipid metabolism through the NR1D1-APOH axis. These findings establish Br as a potential therapeutic for CRC prevention and treatment.