Pancreatic ductal adenocarcinoma (PDAC) poses a formidable challenge in oncology, characterized by its high lethality and limited treatment options. The advanced stage at diagnosis, aggressive metastasis, and the constrained efficacy of conventional therapeutic drugs collectively contribute to the grim prognosis associated with PDAC. Gemcitabine, a nucleoside analog and the longstanding standard chemotherapy for pancreatic cancer, encounters a significant hurdle in its efficacy due to the development of resistance. To establish a cancer-acquired resistance model applicable to Gem-modified drugs, it is crucial to account for the dense extracellular matrix (ECM) composition characteristic of PDAC. In this investigation, we employ three-dimensional (3D) cell culture models, specifically utilizing pancreatic cancer patient-derived organoids (PDOs) within a 3D matrix with tunable density and stiffness by incorporating variations in transglutaminase crosslinking rates. PDAC cells from different patients exhibit diverse adaptations within these altered gel matrix environments, manifesting differences in morphology, doubling time, and responses to drugs. Notably, PDAC cells display pronounced stemness characteristics in the dense matrix, featuring a more rounded and compact appearance and an increase in ABC transporters.Addressing the challenge of gemcitabine resistance, modifications such as gemcitabine conjugates with stearate (Gem-S) have shown promise in preclinical studies. Exploring the effects of both Gem and Gem-S in a viscoelastic-specific ECM model derived from PDAC patient-derived organoids, distinct responses based on matrix stiffness come to light. The physical properties of the matrix exert a significant influence on cellular function, thereby impacting the effectiveness of therapeutic agents. Intriguingly, within a stiffer environment, Gem-S demonstrates higher sensitivity compared to Gem, suggesting the potential application of Gem-S in the dense pathological PDAC environment. Further investigation reveals that Gem-S treatment induces a noteworthy increase in reactive oxygen species (ROS) and HIF-1 expression compared to Gem. Surprisingly, the role of multidrug transporters in Gem-S sensitivity is limited, while the downregulation of NRF (Nrf2) after Gem-S treatment hints at distinct mechanisms underlying the development of drug resistance. This study provides valuable insights into the intricate interplay between gemcitabine resistance and the PDAC microenvironment. Understanding the matrix-specific responses opens avenues for tailored therapeutic interventions, offering the potential for improved outcomes in PDAC patients.

Citation Format: Bo Han, Shuqing Zhao, Edward Agyare, Xueyou Zhu, Jose Trevino, Sherise Rogers, Enrique Velazquez, Jason Brant, Payam Eliahoo, Jonathan Barajas, Ba Xuan Hoang. Impact of gemcitabine modification on redox-driven responses in pancreatic cancer organoids cultured in distinct 3D microenvironments [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 3167.