MORF4L1-Mediated DNA Damage Repair Modulates cGAS-STING Activation and Radiosensitivity in Hepatocellular Carcinoma

<h3>Purpose/Objective(s)</h3> Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with poor prognosis. Radiotherapy (RT) is one of the main treatments for patients with unresectable HCC, but its efficacy has been limited due to inherent or acquired radiation resistance. However, the regulatory mechanisms of radiation resistance in HCC remain unclear. <h3>Materials/Methods</h3> Key DDR genes in HCC were identified by single-cell RNA sequencing (GSE149614). In vitro experiments confirmed that the expression level of MORF4L1 regulates DNA damage repair and susceptibility to radiotherapy of HCC cells. Immunoprecipitation-mass spectrometry was used to explore the core mechanism of MORF4L1 mediating DNA damage repair. Mechanisms of MORF4L1 antagonist combined with radiotherapy to enhance anti-tumor immune response was demonstrated by in vitro cell co-culture model, small molecule inhibitor and genetically engineered mice. <h3>Results</h3> In this study, MORF4L1 was identified as a key DDR gene in HCC by single-cell RNA sequencing (GSE149614). High expression of MORF4L1 mediates poor prognosis and poor RT efficacy in patients with HCC. The expression level of MORF4L1 regulates DNA damage repair and susceptibility to radiation therapy in liver cancer cells. Mechanistically, MORF4L1 mediates acetylation of histone H3 at lysine 4 to promote DNA damage repair. Knocking out MORF4L1 or inhibiting histone acetylation reduced recruitment of PALB2, BRCA2, and RAD51 at sites of DNA damage. Using in vitro cell co-culture models and genetically engineered mice, we demonstrated that the FDA-approved drug argatroban (MORF4L1 antagonist) combined with RT can enhance the anti-tumor immune response by activating the cGAS-STING signaling pathway. <h3>Conclusion</h3> This work highlights the mechanism of MORF4L1 as a key gene in HCC DNA damage repair. RT combined with argatroban enhances anti-tumor immune response by activating cGAS-STING signaling pathway, providing new insights for improving the efficacy of RT for HCC.