Cachexia, marked by continuous skeletal muscle mass loss and severe metabolic disturbances, presents a substantial challenge for pancreatic ductal adenocarcinoma (PDAC) patients. Despite its prevalence and the adverse impact on quality of life and survival rates, effective clinical treatments for cachexia remain elusive. This study aims to bridge this gap by employing innovative in vitro models to investigate the underlying mechanisms of cachexia and identify potential therapeutic targets. To enhance the relevance of cell culture models, modifications were introduced to replicate in vivo conditions, where the muscle is exposed to the ongoing kinetics of constant tumor secretion of active factors. Patient-derived PDAC cells were cultured in a dense 3D stiffness extracellular matrix (ECM) to mimic the hypoxic desmoplastic tumor microenvironment. The conditioned medium from prolonged cultured patient-derived organoids (PDOs) was then used to supplement C2C12-derived myotubes. The investigation focuses on dynamic adaptations in muscle fiber type and metabolism when exposed to tumor paracrine factors. Metabolomic investigations of PDO-conditioned medium (PDO CM) on myotubes revealed distinct metabolic differences compared to non-treatment controls. Discriminatory metabolites included those associated with glycolysis, lipid, amino acid, and fatty acid metabolism. PDO CM induced a significant shift in muscle fiber type from slow-twitch to fast-twitch phenotypes, accompanied by de novel expression of embryonic and neonatal Myosin Heavy Chain (MyHC) isoforms. Fast fiber (F59) staining also confirmed the protein expression. Concurrently, PGC-1a, a master regulator of mitochondrial biogenesis and oxidative metabolism, significantly decreased, along with reduced ATP and Mito tracker staining, indicating a metabolic switch under the influence of tumor paracrine factors. Metabolome results on C2C12 myotubes treated with PDO CM also revealed significantly changed ABC transporter-related pathways, an adaptive process required to optimize substrate use under the influence of tumor secretome. However, the genes involved in the proteasome degradation process, such as MAFbx and MuRF1, did not show altered expression. The establishment of an in vitro cachexia model, focusing on changes in energy metabolism and utilizing muscle fiber type alterations as markers, will deepen our understanding of the mechanisms of cancer-associated cachexia. The insights gained may pave the way for identifying potential therapeutic targets to mitigate muscle wasting in PDAC patients and improve overall outcomes.

Citation Format: Bo Han, Shuqing Zhao, zhi Yang, Jose Trevino, Steven Grossman, Heinz-Josef Lenz, Ba Xuan Hoang. Pancreatic cancer-derived organoids alter muscle fiber type and increased energy consumption leading to cachexia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 382.