[Mutations in the D-loop region of mitochondrial DNA and the ROS level in the tissue of hepatocellular carcinoma].

To explore the relationship between ROS level and mutations in D-Loop region of mtDNA, mutations in the D-Loop region of mtDNA and the ROS level in primary hepatocarcinoma tissues were studied. We amplified the D-Loop region of mtDNA of 20 hepatocarcinomas and their adjacent tissue by PCR and then sequencing. ROS in tissue was measured by flow cytometry. mtDNA mutations were detected in 40% (8 of 20) tumor samples. 53 point mutations were detected in eight tumour samples, including 2 insertions, 11 deletions and 40 point mutations. 75% point mutations were T-C and C-T transition. They were four microsatellites among the mutations. Mutations in the adjacent tissues were always companied with mutations in tumour tissues. The mutation frequency in tumour tissues was higher than that in adjacent tissue. There was a larger unidentified deletion. The ROS level in hepatocarcinoma tissue was much higher than control (P<0.01). Meanwhile, we found the ROS level in hepatocarcinoma tissues with mutated mtDNA D-Loop was higher than that hepatocarcinoma tissue normal mtDNA D-Loop, and the ROS level in hepatocarcinoma adjacent tissue with mutated mtDNA D-Loop was higher than that in hepatocarcinoma adjacent tissue with normal mtDNA D-Loop. It was concluded that the D-Loop region of mitochondrial DNA was a highly polymorphoric and mutable region and mutation rate was relatively high in patients with hepaticellular carcinoma, and the abnormal ROS level might be the point mutation in the mitochondrial DNA and hepatocarcinogenesis related to ROS.