Abstract 6674: Leucine sensing and mTOR activation drive SNAIL-mediated EMT in pancreatic cancer cells

Abstract Background: Pancreatic cancer, characterized by a highly fibrotic and hypovascular tumor microenvironment, possesses unique metabolic adaptations that enable survival and proliferation in malnourished conditions. Aim: This study aimed to compare the metabolic adaptations of pancreatic cancer cells to glucose deprivation with those of liver cancer cells, which are representative of hypervascular tumors. Methods: Three pancreatic cancer cell lines (BxPC-3, Panc-1, MIA PaCa-2) and two liver cancer cell lines (HuH-7, Hep3B) were analyzed. We examined transcriptional expression levels of genes involved in amino acid transport, including LAT1, CD98, CD147, EPCAM, and ASCT2; epithelial-mesenchymal transition (EMT), including SNAIL, SLUG, and ZEB1; and cancer stemness, including CD24, CD44, and DCLK1, under glucose-deprived conditions. Results: Pancreatic cancer cells displayed significantly lower proliferative activity under glucose deprivation compared to liver cancer cells. While glucose-starved cells did not undergo significant apoptosis, they exhibited cell cycle arrest. Pancreatic cancer cells showed mild arrests in both the G0/G1 and G2/M phases, whereas liver cancer cells exhibited a clear G0/G1 arrest. Among amino acid transporters, LAT1 was uniquely upregulated in pancreatic cancer cells, correlating with increased SNAIL (EMT regulator) and DCLK1 (cancer stemness marker) expression. LAT1 knockdown abolished SNAIL upregulation in glucose-starved pancreatic cancer cells, indicating a mechanistic link. Stimulation of LAT1 by branched-chain amino acids (BCAAs; valine, leucine, isoleucine) under glucose-free conditions induced dose-dependent SNAIL upregulation by leucine, accompanied by increased expression of leucine sensors SAR1B and Sestrin2. This activation triggered mTOR pathway signaling, as evidenced by phosphorylation of S6K1 and 4E-BP1. Conversely, rapamycin inhibited mTORC1 activation, suppressing leucine-induced SNAIL upregulation. Conclusion: Pancreatic cancer cells reprogram their metabolism to adapt to energy crises via leucine-mediated upregulation of SNAIL, potentially enhancing metastatic capabilities through EMT. Targeting LAT1 or the mTOR pathway may represent promising therapeutic strategies for pancreatic cancer. Citation Format: Hironori Koga, Yasuko Imamura, Atsutaka Masuda, Hiroyuki Suzuki, Toshimitsu Tanaka, Takahiko Sakaue, Hideki Iwamoto, Toru Nakamura, Takumi Kawaguchi. Leucine sensing and mTOR activation drive SNAIL-mediated EMT in pancreatic cancer cells [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 6674.