Abstract 7240: The role of myeloid cell derived HMGB1 in the development of hepatocellular carcinoma

Abstract Background: High mobility group box 1 (HMGB1) is a non-histone chromatin-associated protein involved in the pathogenesis of chronic liver disease. HMGB1 is expressed in myeloid cells, including conventional dendritic cells (cDCs), which play a major role in the tumor microenvironment. However, whether intracellular myeloid cell-derived HMGB1 is involved in hepatocellular carcinoma (HCC) is unknown. We hypothesize that intracellular HMGB1 drives cDC maturation towards LAMP3+ DCs, allowing effective cytotoxic CD8+ T cell responses to reduce HCC. Methods: We analyzed publicly available scRNA-seq datasets from human HCC for the expression of HMGB1 in all subsets of DCs in HCC tumor and non-tumor tissues and in hepatic draining lymph nodes (dLNs). We generated mice with conditional ablation or overexpression of Hmgb1 in myeloid cells (Hmgb1ΔMye and Hmgb1KI Mye). To induce HCC, 14-day-old male mice were injected i.p. with diethylnitrosamine (DEN) and were sacrificed at 5, 6, 8, and 10 months. Histopathological analysis of livers was performed using H&E staining. Immune cell populations were analyzed in tumor and non-tumor tissues using flow cytometry. cDCs were isolated from tumor and non-tumor tissues by FACS, and RNA-seq analysis was performed. Results: Analysis of scRNA-seq datasets revealed LAMP3+DCs increased in human HCC tumor tissue and hepatic dLNs. LAMP3+DCs displayed increased activation and migration scores. Moreover, HMGB1 was highly expressed in cDCs (CLEC9A+and CD1C+), which can differentiate to LAMP3+DCs. Hmgb1KI Myemice were protected from HCC, whereas control mice developed HCC after 8 months, and Hmgb1ΔMyemice started developing HCC at 5 months. Macroscopic analysis and H&E staining of the livers from Hmgb1ΔMyemice showed more tumors and higher tumor volume than control and Hmgb1KI Myemice. Immunohistochemistry of HCC tumor sections revealed that Hmgb1ΔMye mice have fewer LAMP3+DCs in tumor tissues than control and Hmgb1KI Myemice. Flow cytometry analysis showed that Hmgb1KI Myemice had significantly increased cDCs in tumor tissues and dLNs than control and Hmgb1ΔMye mice. In addition, there was enhanced CD8+T cell apoptosis in the HCC tumor tissues from Hmgb1ΔMyemice. RNA-seq data of cDCs unveiled that pathways involved in antigen presentation were downregulated in Hmgb1ΔMye mice and upregulated in Hmgb1KI Mye mice compared to control mice. Conclusions: Ablation of myeloid-derived HMGB1 accelerates HCC development in mice. Enhancing HMGB1 expression in myeloid cells increased the number and the antigen presentation activity of cDCs. Therefore, increasing HMGB1 expression in cDCs could be a therapeutic approach to protect from HCC. Citation Format: Sai Santosh Babu Komakula, Xiaodong Ge, Wei Chen, Romain Desert, Hui Han, Zhuolun Song, Sukanta Das, Dipti Athavale, Nithyananthan Subramaniyam, Chao Wang, Daniel Lantvit, Abid Anwar, Natalia Nieto. The role of myeloid cell derived HMGB1 in the development of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7240.