LAUSR

The liver is an unique organ in that it is responsible for many metabolic functions. During HCC development, these metabolic machineries are extensively reprogrammed to support the insatiable nutrient requirement of HCC. Cancer stem cells (CSCs) are a small and elusive subpopulation of self-renewing cancer cells with remarkable ability to initiate, propagate, and spread the malignant disease. Liver CSCs reprogram their metabolic pathways to match with the increased metabolic needs for cancer cell survival under adverse conditions. Identifying novel metabolic targets that are related to stemness can offer promising strategies for targeting CSCs and hence to kill and to control their growth. In this study, pathway enrichment analysis of genes that linked metabolism and stemness identified aberrant glycerophospholipid metabolism of which AGPAT4 ranked a top-hit. AGPAT4 upregulation in HCC is tightly correlated with aggressive clinical features, including survival, metastasis, and stemness signatures. Expression of AGPAT4 peaked during early liver progenitor development, decreased during hepatocyte maturation and increased progressively from well-differentiated to poorly differentiated HCCs. Enrichment of AGPAT4 in HCC was mediated by promoter binding of SOX9 to drive AGPAT4 transcriptional activity. AGPAT4 inhibition could mitigate tumor initiation, self-renewal, metastasis and sorafenib resistance. Mechanistic studies revealed an AGPAT4-mediated phosphatidic acid production axis to promote HCC through regulating mTOR signaling. Inhibition of Agpat4 by AAV8 shRNA reduced tumorigenicity and stemness, and sensitized HCC tumors to sorafenib. AGPAT4 overexpression was able to predict sorafenib response in the clinic. Through high-throughput screening coupled with activity-based protein profiling, a cysteine-reacting compound with high binding affinity and selectivity towards AGPAT4 was identified and found to work synergistically with sorafenib to supress HCC. To conclude, AGPAT4 is a novel metabolic driver of oncogenic stemness, dedifferentiation and metastasis in HCC. AGPAT4-induced tumor lineage plasticity may represent an Achilles heel for HCC. Inhibition of AGPAT4 may widen the therapeutic window for sorafenib treatment in the clinic. Citation Format: Kai Yu Ng, Tsz-Lok Fong, Ya Gao, Tin-Lok Wong, Yuan Gao, Jing-Ping Yun, Xin-Yuan Guan, Ming Liu, Clive YS Chung, Stephanie Ma. AGPAT4 as a novel metabolic driver of oncogenic stemness and dedifferentiation in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2429.