Quantitative proteomics analysis of radiation-induced rectal injury in rectal cancer patients undergoing radiotherapy.

Radiation-induced rectal injury (RRI) affects perioperative treatment and the postoperative quality of life in patients with rectal cancer undergoing radiotherapy. This study aimed to clarify the molecular mechanisms of RRI and identify potential therapeutic targets. Hematoxylin-eosin and Masson's staining were utilized to evaluate RRI. Initially, 16 rectal samples were examined using data-independent acquisition proteomics to identify the differentially abundant proteins (DAPs). Subsequently, parallel reaction monitoring (PRM) was employed to validate DAP expression. Furthermore, DAP levels were assessed using enzyme-linked immunosorbent assay (ELISA) in 118 patients with rectal cancer. Pathologic examination revealed manifestations of RRI in rectal samples. A total of 1391 DAPs were identified, with 619 upregulated and 772 downregulated. Functional annotation revealed that these proteins are primarily involved in regulating actin cytoskeleton, metabolic pathways, and immune pathways. Enrichment analysis indicated significant enrichment of DAPs in pathways, including macrophage chemotaxis, neutrophil extracellular traps, and lipid metabolism. The expression of significantly upregulated DAPs (LBP, ITIH4, SERPINA3, FN1, PLG, HRG, FGA, and SAA1) in the relevant pathway was validated using PRM. ELISA revealed that the SAA1 level in the RRI group was significantly high. In conclusion, our study provides a proteomic profile of RRI, identifying biological markers and potential molecular regulatory mechanisms. SIGNIFICANCE: Radiation-induced intestinal injury (RII) significantly impacts the postoperative quality of life in patients undergoing pelvic radiotherapy. However, the current understanding of the mechanism behind RII remains unclear. In this study, Hematoxylin-eosin and Masson's staining were used to assess RRI. We employed data-independent acquisition proteomics analysis to characterize the proteomic profile associated with RII. Through this analysis, we identified differentially expressed proteins(DEPs) and potential molecular pathways implicated in RII. Parallel reaction monitoring and enzyme-linked immunosorbent assay further employed to validate the expression of DEPs. Our findings offer novel insights into the prevention and treatment strategies for RII, thereby potentially improving the clinical outcomes and quality of life for affected patients.