Testis-Specific MAGEA3/6 Regulate Glycolysis to Promote Metabolic Flexibility and Reveal Therapeutic Vulnerabilities in Pancreatic Cancer Cells
Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumor characterized by metabolic plasticity that enables cancer cells to survive nutrient deprivation and therapeutic stress. Melanoma-associated antigens A3 and A6 (MAGEA3/6), members of the cancer-testis antigen family with a previously identified protective role in spermatogenesis during nutritional stress, have been implicated in cancer progression and metabolic regulation. However, their contribution to metabolic adaptation in pancreatic cancer remains poorly understood. Here, we investigated the molecular mechanisms underlying MAGEA3/6-mediated resistance to glycolytic inhibition using complementary gain- and loss-of-function models, pharmacological inhibition of metabolic pathways, cellular metabolic assays, and integrated transcriptomic, proteomic, metabolomic, and lipidomic analyses. MAGEA3/6 expression enhanced resistance to 2-deoxy-D-glucose (2-DG), with MAGEA6-expressing MIA PaCa-2 cells exhibiting a greater than 2.5-fold increase in the half-maximal inhibitory concentration (IC50). Conversely, MAGEA3/6 depletion reduced clonogenic growth and migration and increased sensitivity to 2-DG. Resistance persisted despite pharmacological inhibition of mTORC1, the pentose phosphate pathway, or glutaminase, suggesting metabolic adaptations beyond these pathways. Unexpectedly, MAGEA6 expression was associated with increased rather than decreased AMPK1 protein abundance, contrasting with previously reported MAGEA3/6-mediated AMPK degradation and suggesting context-dependent regulation of this master regulator of cellular metabolism. MAGEA6 also reduced hexokinase HK1 and HK2 abundance while increasing several downstream glycolytic enzymes, revealing discordant regulation of glycolysis. Seahorse analyses and integrated multi-omics profiling identified extensive remodeling of mitochondrial metabolism, glutamine-aspartate metabolism, phospholipid composition, lipid storage, and redox homeostasis. Interestingly, despite enhanced resistance to glycolytic inhibition, MAGEA6-expressing cells exhibited increased sensitivity to hydrogen peroxide-induced oxidative stress, revealing a potential metabolic vulnerability. Given that MAGEA3/6 are physiologically expressed primarily in the male germline during early spermatogenesis, a process highly sensitive to metabolic and oxidative stress, these findings also raise important questions about their physiological roles in protecting developing germ cells and maintaining metabolic and redox homeostasis. Together, our findings recognize MAGEA3/6 as regulators of metabolic plasticity in PDAC and highlight how understanding their molecular functions in both spermatogenesis and cancer may uncover previously unrecognized metabolic vulnerabilities and potential therapeutic opportunities.