Single-cell landscape reveals PLPP2 upregulation underlying radiotherapy resistance and immune microenvironment remodeling in pancreatic cancer.

The main purpose of this study was to investigate the molecular mechanisms underlying radiotherapy resistance in pancreatic cancer by integrating single-cell transcriptomic analysis with multicenter clinical cohorts. Using machine learning algorithms and genomic data, we identified key genes associated with radiotherapy response by analyzing radiotherapy sensitivity in our center's single-cell cohort together with external multicenter cohorts, combined with immune microenvironment remodeling and metabolic reprogramming. Radiotherapy resistance- and prognosis-related genes were identified using a random survival forest (RSF) model with high predictive performance, demonstrating satisfactory accuracy and robustness across both internal and external validation cohorts. Among the identified candidates, PLPP2 emerged as a key immune-related gene. Nomogram construction, survival analysis, and receiver operating characteristic (ROC) curve analysis further confirmed the predictive value and robustness of the radiotherapy resistance risk model. Single-cell transcriptomic profiling and cell-cell communication analyses revealed the cellular distribution of PLPP2 and its critical role in shaping the tumor immune microenvironment. High PLPP2 expression was associated with unfavorable survival outcomes, reduced infiltration of antitumor immune cells, and extensive immune microenvironment remodeling. In vivo experiments further demonstrated the potential of PLPP2 as a biomarker for predicting metabolic status, immune landscape, and responsiveness to immune checkpoint inhibitors in pancreatic cancer. Collectively, PLPP2 may have potential predictive value in stromal remodeling, metabolic reprogramming, immune heterogeneity, and radiotherapy efficacy in pancreatic cancer. These findings provide new insights into the molecular basis of radiotherapy resistance, identify a clinically relevant biomarker for prognosis and therapeutic response, and offer a foundation for precision treatment strategies in pancreatic cancer.