ETV4 lysine 2-hydroxyisobutyrylation promotes intrahepatic cholangiocarcinoma progression by suppressing ferroptosis through TXNIP downregulation.

Aberrant lysine 2-hydroxyisobutyrylation (Khib) is a novel post-translational modification implicated in tumor progression, but its role in intrahepatic cholangiocarcinoma (ICC) remains poorly defined. Here, we identify a specific Khib modification at lysine 97 (K97) of the oncogenic transcription factor ETV4, which is significantly upregulated in ICC and strongly associated with tumor metastasis and poor patient outcomes. Functional assays demonstrate that ETV4 K97-Khib enhances ICC cell proliferation, invasion, and distant metastasis by promoting ferroptosis resistance. Mechanistically, ETV4 K97-Khib represses transcription of the ferroptosis inducer TXNIP and simultaneously facilitates its post-translational degradation through upregulation of the SUMO E3 ligase ZBED1, leading to increased SUMOylation of TXNIP. This dual mechanism reduces TXNIP levels and potently suppresses ferroptosis. KAT2A and HDAC1 were identified as the acyltransferase and deacylase controlling ETV4 Khib dynamics, respectively. Notably, the small-molecule compound thiostrepton significantly inhibits ETV4 K97-Khib, thereby promoting ferroptosis and suppressing ICC cell migration, invasion, and lung metastasis. Together, our study reveals a novel ETV4 Khib-driven mechanism underlying ferroptosis suppression and malignant progression in ICC, and highlights ETV4 Khib as a potential therapeutic target in cholangiocarcinoma.