The lipid peroxidation-derived DNA adduct γ-OHPdG as a diagnostic and prognostic biomarker in hepatocellular carcinoma

Abstract

Purpose: Chronic inflammation and lipid peroxidation (LPO) are associated with the pathogenesis of hepatocellular carcinoma (HCC), and γ-hydroxy-1, N²-propanodeoxyguanosine (γ-OHPdG) is a promutagenic DNA adduct derived from LPO. This study aimed to examine the relationship between γ-OHPdG and the progression of liver carcinogenesis.

Methods: Primary HCC specimens were obtained from 228 patients and cirrhosis specimens from 46 patients. The patients were followed up with after surgery via outpatient visits and telephone calls. The levels of γ-OHPdG were determined by immunohistochemical analysis in the carcinomatous tissues together with adjacent and cirrhosis tissues.

Results: γ-OHPdG levels in the cancerous tissues were significantly higher compared to adjacent tissues (P < 0.001) and also higher than the ones from the tissues of cirrhosis patients. Along with tumor size, histological grade, MVI grade, T stage, the percentage of ki67-positive cells and HCC progression, γ-OHPdG levels in cancerous tissues showed a gradually increasing trend. Moreover, prognostic analysis showed that higher γ-OHPdG levels in cancerous tissues were strongly correlated with lower overall survival (P < 0.001), lower intrahepatic recurrence-free survival (P < 0.001) and lower distant metastasis-free survival (P < 0.05). There was a trend, although not statistically significant, of increased levels of γ-OHPdG in cirrhosis cases that advanced to HCC, whereas γ-OHPdG levels reversely correlated with the period of time observed for cirrhosis advanced to HCC.

Conclusions: These results suggest that γ-OHPdG is a prognostic biomarker for predicting outcomes in HCC, and may serve as a prospective indicator for predicting HCC in cirrhosis patients.

Keywords: cirrhosis; hepatocellular carcinoma; occurrence; prognosis; γ-OHPdG.

Figure 1

The levels of γ-OHPdG by IHC staining in the development of HCC. (A) The levels of γ-OHPdG in the adjacent tissues, primary tumors, the recurrent and metastatic tumor tissues (20×); (B, C) Comparison of the levels of γ-OHPdG in HCC and the adjacent tissues; (D–G) The histogram plot shows γ-OHPdG levels in tumor size, Edmondson-Steiner grades I–IV, MVI grades 0-2, T stages T1a-T4 HCC patients, respectively; (H) Dot plot between γ-OHPdG levels and ki67 percentage scores; (I, J) γ-OHPdG levels between the recurrent tumors/metastatic tumors and their primary HCC tissues.*P < 0.05, **P < 0.01, ***P < 0.001 (Wilcoxon rank sum test and Kruskal-Wallis test).

Figure 2

The γ-OHPdG levels and the prediction of prognosis in HCC patients. (A–C) Kaplan-Meier survival curve analysis of OS, PFS and MFS rates with high and low γ-OHPdG levels in HCC patients, respectively; (D–F) ROC curve validation of the prognostic value of the γ-OHPdG; (G–I) Time-dependent ROC curve analysis of the γ-OHPdG levels for OS, MFS and RFS.

Figure 3

The γ-OHPdG levels in cirrhosis patients. (A, B) The levels of γ-OHPdG (representatives of IHC staining) in cirrhosis tissues. (C, D) γ-OHPdG IHC examination of cirrhosis tissues advanced to HCC; (E) The comparison of γ-OHPdG levels in HCC and the cirrhosis tissues; (F) Dot plotting and Spearman fitting show the correlation between γ-OHPdG levels and the time of cirrhosis advanced to HCC. *** indicates P < 0.001 (Wilcoxon rank sum test).