KRAS-ERK signaling drives metastasis in colorectal cancer via phosphorylation-dependent activation of the ZBTB20-TGFBR2 axis.

BACKGROUND

Metastatic colorectal cancer (CRC) harboring KRAS mutations presents a major therapeutic challenge due to its aggressive nature, poor prognosis, and resistance to EGFR-targeted therapies. This study aimed to identify novel drivers of metastasis specifically in KRAS-mutant CRC and to elucidate the underlying molecular mechanisms to undercover new therapeutic vulnerabilities.

METHODS

We integrated data from clinical databases (TCGA, CPTAC) with experimental validation using human CRC cell lines, a tissue microarray, and two distinct in vivo metastasis models (liver and lung colonization). ZBTB20 expression and function were analyzed by IHC, Western blotting, Transwell assays, and RNA-seq integrated with ChIP-seq data. The mechanism of ZBTB20 regulation was investigated via co-immunoprecipitation, mass spectrometry, truncation analysis, site-directed mutagenesis, and luciferase reporter assays. Statistical significance was determined using Student's t-tests, ANOVA, and survival analysis.

RESULTS

ZBTB20 expression was significantly upregulated with metastatic progression specifically in KRAS-mutant CRC patients and correlated with reduced overall survival. Functionally, ZBTB20 promoted CRC cell migration, invasion, EMT in vitro, and drove metastatic colonization in vivo. Mechanistically, KRAS/ERK signaling directly phosphorylated ZBTB20 at Threonine 138, 142, and 232, a step essential for its nuclear localization and pro-metastatic activity. Integrating transcriptomic and cistromic data, we identified TGFBR2 as a direct transcriptional target of activated ZBTB20. Notably, pharmacological degradation of TGFBR2 with the inhibitor ITD-1 potently abrogated metastatic outgrowth in both liver and lung colonization models.

CONCLUSIONS

Our findings delineate a novel KRAS-ERK-ZBTB20-TGFBR2 signaling axis that is a critical driver of metastasis colonization in KRAS-mutant CRC. The robust efficacy of a TGFBR2 degrader in multiple in vivo models validates this axis as a viable therapeutic target, offering a promising strategy to inhibit metastatic progression in patients with this aggressive disease.