Abstract Hepatocellular carcinoma (HCC) frequently arises from steatotic and fibrotic livers, yet molecular factors linking metabolic dysregulation to tumor-promoting hepatic microenvironments remain incompletely defined. We aimed to identify transporter genes associated with HCC risk and elucidate their mechanistic role in steatohepatitis-related hepatocarcinogenesis. Using the GSE10143 cohort, we screened 617 transporter genes curated from the Transporter Classification Database for prognostic relevance based on Cox proportional hazards modeling of overall survival. Candidate genes were validated by RNA sequencing of liver biopsy specimens from 94 patients with metabolic dysfunction-associated steatotic liver disease (MASLD) (12 with HCC) obtained between 2016 and 2020, following institutional ethical approval. Functional studies were conducted in C57BL/6 mice with hepatic overexpression of solute carrier family 12 member 2 (SLC12A2)—a Na+-K+-Cl− cotransporter—via AAV8, followed by feeding with a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for six weeks to induce diet-associated steatohepatitis. In vitro assays were performed using a normal hepatocyte cell line and Hep3B cells with stable SLC12A2 overexpression or shRNA-mediated knockdown. From the transporter gene screening, SLC12A2 showed the highest hazard ratio for poor survival and was also associated with increased late (2 years) post-hepatectomy recurrence, implying enhanced carcinogenic potential of background liver tissue. In the MASLD cohort, hepatic SLC12A2 expression was significantly higher in HCC cases and positively correlated with fibrosis stage and liver stiffness. In mice, hepatic SLC12A2 overexpression exacerbated CDAHFD-induced steatohepatitis—evidenced by increased liver weight, serum ALT levels, hepatic triglyceride content, Sirius red-positive area, and fibrogenic gene expression. Cleaved caspase-3 and Ki-67 staining indicated increased hepatocellular apoptosis and compensatory proliferation, features typical of chronic liver injury. Orthotopic implantation of Hepa1-6 cells resulted in significantly larger tumors, demonstrating a tumor-promoting microenvironment. In vitro, SLC12A2 overexpression enhanced palmitate-induced lipid droplet formation, whereas shRNA-mediated knockdown suppressed it. Expression of genes involved in fatty acid synthesis and oxidation remained unchanged, but glycerol release was decreased, indicating suppression of lipolysis as the primary mechanism. Our findings suggest that SLC12A2 promotes hepatic steatosis and fosters a tumor-promoting microenvironment by repressing lipolysis. Its overexpression identifies high-risk MASLD livers predisposed to HCC and represents a potential therapeutic target for metabolic liver disease-associated hepatocarcinogenesis. Citation Format: Yotaro Kudo, Ryosuke Tateishi, Mitsuhiro Fujishiro. SLC12A2 drives a tumor-promoting microenvironment and poor prognosis in hepatocellular carcinoma by suppressing lipolysis abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2258.
Kudo et al. (Fri,) studied this question.