Identification of Aberrant Expression of Gemcitabine-Targeting Proteins in Drug-Resistant Cells Using an Activity-Based Gemcitabine Probe.

Gemcitabine-based monotherapy or combination therapy has become the standard treatment for locally advanced and metastatic pancreatic cancer. However, the emergence of resistance within weeks of treatment severely compromises therapeutic efficacy. The intricate biological process of gemcitabine resistance in pancreatic cancer presents a complex challenge, as the underlying mechanisms remain unclear. Identifying the target protein of gemcitabine is crucial for studying its drug-resistance mechanism. An activity-based probe is a powerful tool for studying drug target proteins, but the current lack of activity-based gemcitabine probes with robust biological activity hinders research on gemcitabine. In this study, we developed three active probes based on gemcitabine, among which Gem-3 demonstrated excellent stability and labeling efficacy. We utilized Gem-3 in conjunction with chemical proteomics to identify intracellular target proteins. We identified 79 proteins that interact with gemcitabine, most of which were previously unknown and represented various functional classes. Additionally, we validated the increased expression of IFIT3 and MARCKS in drug-resistant cells, along with the activation of the NF-κB signaling pathway. These findings substantially contribute to our comprehension of gemcitabine's target proteins and further our understanding of the mechanisms driving gemcitabine resistance in pancreatic cancer cells.