Fatty Liver Stabilizes MYC to Drive Replacement Metastases in Colorectal Cancer

Researchers combined human liver metastasis samples with mouse models of colorectal cancer under high-fat conditions. They quantified metastasis morphology, measured MYC protein half-life, proline levels, and collagen architecture via mass spectrometry and histology. Patients with steatosis showed a marked shift toward infiltrative replacement growth, confirming the metabolic cue alters tumor-liver interface behavior rather than merely providing a permissive niche. This connects rising metabolic disease prevalence directly to the dominant pattern of liver metastasis that drives colorectal cancer mortality.

The mechanism involves elevated fatty acids that prevent MYC degradation, amplifying transcription of pyrroline-5-carboxylate synthase and thereby proline synthesis. Excess proline fuels collagen production that facilitates cancer-cell invasion into hepatic plates. This pathway was validated by MYC knockdown and proline supplementation rescue experiments, establishing a causal metabolic axis. The finding reframes fatty liver from comorbidity to active driver, consistent with prior observational data linking obesity to poorer colorectal outcomes but supplying the missing mechanistic step.

Trial enrichment strategies now emerge: MYC-targeted agents in development may achieve higher response rates when restricted to steatotic patients with replacement metastases. Future studies must test whether dietary or pharmacologic reversal of steatosis before metastasis formation reduces replacement incidence and improves survival. Large prospective cohorts with serial imaging and biopsy will be required to quantify risk modification and confirm generalizability beyond the current European cohorts.