TRIM27-Cas9–loaded EVs suppress HCC proliferation and enhance responsiveness to anti–PD-1 therapy by promoting ACSL4-mediated ferroptosis

Inducing ferroptosis in hepatocellular carcinoma (HCC) cells represents an important therapeutic strategy, but intrinsic resistance mechanisms often limit efficacy. Therefore, elucidating the mechanisms underlying ferroptosis resistance in HCC cells can facilitate the development of effective therapeutic strategies. Here, we performed genome-wide CRISPR/Cas9 library screens to identify TRIM27 as a key determinant of ferroptosis resistance. TRIM27 knockdown markedly potentiated erastin-induced ferroptosis in HCC cells, whereas TRIM27 overexpression suppressed the expression of fatty-acid metabolic enzymes including ACSL4 and reduced oxidized lipid accumulation. Mechanistically, TRIM27 directly binds with ACSL4 and promotes its K48-linked ubiquitination and degradation, thereby attenuating ferroptosis in HCC cells. Furthermore, we developed TRIM27-Cas9-loaded EVs with robust editing efficiency. These engineered EVs were readily internalized by HCC cells and preferentially accumulated in the liver. Functionally, TRIM27-Cas9-loaded EVs inhibited HCC cell proliferation by enhancing ACSL4-mediated ferroptosis and significantly improved the anti-tumor efficacy of anti-PD-1 therapy in HCC. Collectively, our findings suggest that TRIM27 confers ferroptosis resistance via facilitating K48-linked ubiquitination and subsequent proteasomal degradation of ACSL4. TRIM27-Cas9-loaded EVs restore cellular sensitivity to ferroptosis, inhibit HCC proliferation, and sensitize HCC lesions to anti-PD-1 immunotherapy.