Circulating Cell-free Mitochondrial DNA In Serum As Non-invasive Biomarker In HBV Related HCC Risk Prediction

Backgrounds Increasing evidence has indicated that mitochondrial DNA(mtDNA)is closely related with various human cancers.Abnormal alternations of mitochondrial DNA,including genetic mutation and copy numbers variation,may affect the susceptibility to tumors,such as hepatocellular carcinoma(HCC),lung cancer,breast cancer and so on.The majority of recent studies have been focused on evaluating mtDNA content in tumor tissues and in peripheral blood lymphocytes(PBLs)and the correlation with tumors.This study is to explore the association of circulating mtDNA content and HBV-related HCC risk in hepatitis B(HBV)patients.Methods This case-control study included 156 hepatitis B virus(HBV)-related HCC cases,which including male 128 andfemale 28,with mean age of54.0 ± 9.7,and 312 age–matched cancer-free HBV controls,which including male 246 and female 66,with mean age of 54.2 ± 9.4.We determined the mtDNA content in serum DNA samples using quantitative real-time PCR and compared the differences between groups by Wilcoxon rank test.The association between mtDNA content and HCC risk was evaluated by logistical regression model using univariate and multivariate analyses.To compare with the effect of mtDNA and some current clinical parameters,such AFP,AST,ALT,ALP and GGT,we further evaluated the associations between these variables and HBV-HCC risk in this population.Results The serum mtDNA content in HBV-HCC cases(median 1.210,quartile range0.301–3.593)was lower than that in non-cancer HBV controls(median1.616,quartile range 0.369-3.987).Furthermore,the older patients had lower levels of mtDNA content than younger patients,which with more evident in non-cancer HBV controls.There was no significant association observed between mtDNA and HBV-related HCC risk in overall population.However,patients with lower mtDNA content exhibited significantly higher risk in younger and non-cirrhosis patients.Specifically,the odd ratios(OR)of increased HCC cancer risk conferred by low mtDNA content was 1.731(95%CI,0.999-2.999,P=0.50)by univariate analysis and 2.209(95CI%,1.187-4.111,P=0.012)by multivariate analysis with adjusting for all host variables excepting for age in younger patients.And also the OR of increased HCC cancer risk conferred by low mtDNA content was 2.177(95%CI,1.086-4.363,P =0.028)by univariate analysis and 2.049(95CI%,1.002-4.118,P=0.049)by multivariate analysis with adjusting for all host variables excepting for cirrhosis in subgroup patients without cirrhosis.We further observed a significant association between higher level of AFP and increased HBV-related HCC risk in the sub-populaiton analysis.However,there was no significant association observed between AST,ALT,ALP or GGT and HBV-related HCC risk.Conclusions Serum mtDNA content may serve as a potential non-invasive biomarker in HBV-related HCC risk prediction.Our finding needs further validation by prospective studies with a larger sample size to explore its clinical significance.