Construction of Genetically Encoded Biosensors to Monitor Subcellular Compartment-Specific Glutathione Response to Chemotherapeutic Drugs in Acute Myeloid Leukemia Cells.

Glutathione (GSH), the constituent of the redox buffer system, is a scavenger of reactive oxygen species (ROS), and its ratio to oxidized glutathione (GSSG) is a key indicator of oxidative stress in the cell. Acute myeloid leukemia (AML) is a highly aggressive hematopoietic malignancy characterized by aberrant levels of reduced and oxidized GSH due to oxidative stress. Therefore, the real-time, dynamic, and highly sensitive detection of GSH/GSSG in AML cells is of great interest for the clinical diagnosis and treatment of leukemia. The application of genetically encoded sensors to monitor GSH/GSSG levels in AML cells is not explored, and the underlying mechanism of how the drugs affect GSH/GSSG dynamics remains unclear. In this study, we developed subcellular compartment-specific sensors to monitor GSH/GSSG combined with high-resolution fluorescence microscopy that provides insights into basal GSH/GSSG levels in the cytosol, mitochondria, nucleus, and endoplasmic reticulum of AML cells, in a decreasing order, revealing substantial heterogeneity of GSH/GSSG level dynamics in different subcellular compartments. Further, we investigated the response of GSH/GSSG ratio in AML cells caused by Prussian blue and Fe 3 O 4 nanoparticles, separately and in combination with cytarabine, pointing to steep gradients. Moreover, cytarabine and doxorubicin downregulated the GSH/GSSG levels in different subcellular compartments. Similarly, live-cell imaging showed a compartment-specific decrease in response to various drugs, such as CB-839, parthenolide (PTL), and piperlongumine (PLM). The enzymatic activity assay revealed the mechanism underlying fluctuations in GSH/GSSG levels in different subcellular compartments mediated by these drugs in the GSH metabolic pathway, suggesting some potential therapeutic targets in AML cells.