Decreased mtDNA Copy Number of Gastric Cancer: a New Tumor Marker?

OBJECTIVE To explore the relationship between mtDNA (mitochondrial DNA) and gastric cancer by comparing the difference of mtDNA copy number in gastric cancers and paracancerous tissues.

METHODS The HV1 (hypervariable region) and HV2 of the mitochondrial D-loop region from 20 cases of gastric cancer and 20 paracancerous tissues were amplified by PCR with β-actin serving as a quantitative standard marker. The products were separated by polyacrylamide gel electrophoresis (PAGE) and silver stained in order to compare the difference in mtDNA copy number between gastric cancers and paracancerous tissues. The mtDNA copy number was determined for gastric cancers having various pathological characteristics and the results compared with previous immunohistochemical staining of the tumors.

RESULTS There was a significantly quantitative difference in HV1, HV2 (standardized with β-actin) between gastric cancers and paracancerous tissues (P<0.01). The mtDNA copy number was associated with important enzymes in the nucleus such as AKP, cAMP-PDE and cGMP-PDE (P< 0.05), but not associated with tumor histological type and invasive depth (P> 0.05).

CONCLUSION The occurrence of gastric cancer was closely associated with decreased mtDNA copy number, which may be a new tumor marker.