Hypoxia-Induced Creatine Uptake Reprograms Metabolism to Antagonize PARP1-Mediated Cell Death and Facilitate Tumor Progression in Hepatocellular Carcinoma

Recently, a PARP1-dependent cell death process termed "parthanatos" that is driven by DNA damage has emerged as a crucial regulator of tissue homeostasis and tumorigenesis. Hypoxia is a hallmark of solid tumors and profoundly affects the malignant phenotypes of cancer cells. In this study, we investigated the cross-talk between parthanatos and hypoxia. Despite causing DNA damage, hypoxia failed to induce parthanatos in hepatocellular carcinoma (HCC). The creatine transporter SLC6A8 promoted parthanatos antagonism and malignant phenotypes in hypoxic HCC cells. Hypoxia-induced creatine accumulation drove metabolic reprogramming and antagonized parthanatos. Mechanistically, creatine elevated serpin peptidase inhibitor class E member 1 (SERPINE1) expression through MPS1-mediated Smad2/3 phosphorylation and formed a creatine/SERPINE1/hypoxia-inducible factor 1α-positive feedback loop. SERPINE1 facilitated ubiquitin-specific protease 10 (USP10)-mediated deubiquitination and stabilization of pyruvate kinase, liver, and red blood cell by forming a SERPINE1-USP10-pyruvate kinase, liver, and red blood cell complex. USP10 contained a strong poly(ADP-ribose)-binding motif, and SERPINE1 reversed the attenuated deubiquitination activity of USP10 caused by the direct binding of poly(ADP-ribose) under hypoxia. The SLC6A8 inhibitor RGX-202 exerted potent antitumor activity alone and in combination with lenvatinib in patient-derived xenografts and primary HCC mouse models. Overall, this study identified intracellular creatine accumulation as a mechanism that allows hypoxic cancer cells to circumvent parthanatos and as a therapeutic target in HCC. SIGNIFICANCE: The creatine transporter SLC6A8 drives creatine uptake in hypoxic cancer cells to induce parthanatos antagonism and metabolic reprogramming, which can be overcome by inhibiting SLC6A8 as a strategy for treating hepatocellular carcinoma.