Circulating Cell-Free Mitochondrial DNA and Inflammation in Older Adults with Pancreatic Cancer: Results from an Exploratory Study

Pancreatic cancer (PaCa) is among the most aggressive malignancies of the digestive system. Inflammation plays a critical role in tumor growth and dissemination, with soluble cytokines serving as messengers that facilitate interactions between immune and cancer cells. The release of cell-free mitochondrial DNA (cf-mtDNA) into the bloodstream has been identified as a potent proinflammatory trigger, acting as a mitochondrial-derived damage-associated molecular pattern (mtDAMP). Whether a relationship exists between circulating cf-mtDNA (ccf-mtDNA) unloading and inflammation in PaCa remains unclear. In this study, we quantified ccf-mtDNA levels in plasma/serum samples from PaCa patients and healthy controls and examined their association with inflammatory markers. Analyses were conducted on 14 participants: 3 controls (mean age: 52.0 ± 16.0 years, 67% women) and 11 PaCa patients (mean age: 69.1 ± 10.0 years, 27% women). Circulating levels of ccf-mtDNA in PaCa patients did not show differences compared to controls (p = 0.06). In contrast, concentrations of interleukin (IL)-8, IL-17, and interferon-gamma were significantly higher in PaCa patients. Stratification of PaCa patients based on the median ccf-mtDNA concentration revealed significantly higher levels of IL-4, IL-9, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein 1-beta in those with ccf-mtDNA levels above the median (p < 0.05). Significant positive associations were also observed between levels of ccf-mtDNA and IL-8, fibroblast growth factor, and MCP-1. These results suggest a potential association between elevated ccf-mtDNA levels and increased concentrations of proinflammatory cytokines, especially in PaCa patients with an unfavorable prognosis. Further research with larger cohorts is required to validate these findings and assess the prognostic value of these biomarkers.