Absence of correlation between serum CRP levels and mitochondrial D-loop DNA mutations in gastro-oesophageal adenocarcinoma

Both inflammation and mitochondrial DNA (mtDNA) mutation are thought to play a role in the many human cancers. The aim of this study was to evaluate the relationship between inflammation and accumulation of mitochondrial DNA (mtDNA) mutations in the D-loop region in carcinogenesis of gastro-oesophageal adenocarcinomas. Blood samples of 20 patients with gastro-oesophageal adenocarcinoma were taken for measurement of serum C-reactive protein (CRP) concentration. Direct sequencing of mtDNA in the D-loop region was done in the 20 adenocarcinoma samples and their corresponding surrounding non-cancerous tissue. Sequences were compared with existing mtDNA databases to identify mutations. mtDNA mutations in the D-loop region occur commonly with almost identical frequency in both non-cancerous tissue (3.0 ± 1.6) and adenocarcinoma (3.1 ± 1.9) (P = 0.916, paired t-test). CRP levels are not predictive of the number of D-loop mutations in both adenocarcinoma (β: -0.131; 95% CI: -2.354-1.364; P = 0.583) and non-cancerous tissue samples (β: 0.130; 95% CI: -1.125-1.933; P = 0.586). Five new mutations were identified that were not recorded previously in mtDNA databases. D-loop mtDNA mutations are common in both gastro-oesophageal adenocarcinoma and surrounding non-cancerous tissue. However, the accumulation of such mutations appears to occur independent of systemic inflammation. The frequency of D-loop mutations is likely not useful as a marker for carcinogenesis in gastro-oesophageal adenocarcinoma.