Multiplicity (multiple)’, `tumor size ( 5 cm)’, `HBsAg (positive)’, `serum AFP ( 20 ng/ml)’, `grade (III V)’, `cirrhosis (yes)’, `stage (III V)’, and `relapse (yes)’. Results revealed that patients with low SIRT3 expression in all subgroups survived shorter than those with high SIRT3 expression (Fig. 6). Unfortunately, it seemed that SIRT3 expression was not of significance in 18334597 predicting the Felypressin biological activity recurrence-free survival for these subgroups of HCC cases (Fig. S2). Our further study indicated that low SIRT3 expression in HCC patients with tumor size (,5 cm), grade (I I), or stage (I I) associated with poorer overall survival but not recurrence-free survival (Fig. S3).Figure 5. Correlation of low SIRT3 expression in HCC tissue with unfavorable overall survival and recurrence-free survival. Probabilities of overall survival (A) and recurrence-free survival (B) of total 248 HCC patients were analyzed by Kaplan-Meier survival analysis (log-rank test). doi:10.1371/journal.pone.0051703.gcontrol group) the positive clinical outcome. As a result, the cutoff score for low SIRT3 expression is 2.50, which indicated that tumor were defined as one with low SIRT3 expression when the IHC score was not higher than 2.50.Association between SIRT3 Expression and Clinicopathological VariablesSince SIRT3 was remarkably downregulated in HCC cell lines and cancer tissues, we next further examined its expression in 248 paraffin-embedded HCC tissues. According to the results of TMAbased IHC, SIRT3 was mainly presented in cytoplasm (Fig. 3A?F). Out of more than 65 of cases, SIRT3 expressions in HCC were lower than those in corresponding adjacent nontumor tissues. Furthermore, based on the definition of cutoff score, low SIRT3 expression was observed in 67.3 (167/248) of HCC cases.Univariate and Multivariate Analyses of Prognostic Variables in HCC PatientsTo evaluate the representative of our samples, univariate analyses were applied. Results indicated that SIRT3, as well as tumor size, serum AFP level, tumor multiplicity, clinical stage, vascular invasion, tumor differentiation, and relapse, was responsible for ML-281 site outcome of HCC patient who underwent surgical resection (Tables 2 and S1).SIRT3 as a Prognostic Biomarker in HCCFigure 6. Relation of SIRT3 expression with overall survival in morphologic and pathological HCC subgroups. Survival analysis was performed in subgroups according to the factors that are attributed to worse outcome of HCC patients, using Kaplan-Meier survival analysis (log-rank test). doi:10.1371/journal.pone.0051703.gMultiple Cox regression analysis was conducted to determine the independent prognostic value of SIRT3. After adjusted for the prognostic factors established in univariate analysis, a significant correlation of low SIRT3 expression with worse overall survival (Hazard Ratio (HR) 0.555, P = 0.016) was observed (Table 3). However, SIRT3 was revealed not to be an independent marker of recurrence-free survival (Hazard Ratio (HR) 0.712, P = 0.123) for HCC patients (Table S2). Taken together, our data suggested SIRT3 as an independent prognostic biomarker for overall survival in postsurgical patients with primary HCC.DiscussionHCC is a heterogeneous cancer with a very high mortality. Searching for valuable biomarkers for HCC diagnosis and prognostic prediction has been attracting more and more interests. In recent years, many potential biomarkers have been disclosed to be of diagnostic value in HCC, such as serum DKK1 [24], serum anti-Ku86 [25.Multiplicity (multiple)’, `tumor size ( 5 cm)’, `HBsAg (positive)’, `serum AFP ( 20 ng/ml)’, `grade (III V)’, `cirrhosis (yes)’, `stage (III V)’, and `relapse (yes)’. Results revealed that patients with low SIRT3 expression in all subgroups survived shorter than those with high SIRT3 expression (Fig. 6). Unfortunately, it seemed that SIRT3 expression was not of significance in 18334597 predicting the recurrence-free survival for these subgroups of HCC cases (Fig. S2). Our further study indicated that low SIRT3 expression in HCC patients with tumor size (,5 cm), grade (I I), or stage (I I) associated with poorer overall survival but not recurrence-free survival (Fig. S3).Figure 5. Correlation of low SIRT3 expression in HCC tissue with unfavorable overall survival and recurrence-free survival. Probabilities of overall survival (A) and recurrence-free survival (B) of total 248 HCC patients were analyzed by Kaplan-Meier survival analysis (log-rank test). doi:10.1371/journal.pone.0051703.gcontrol group) the positive clinical outcome. As a result, the cutoff score for low SIRT3 expression is 2.50, which indicated that tumor were defined as one with low SIRT3 expression when the IHC score was not higher than 2.50.Association between SIRT3 Expression and Clinicopathological VariablesSince SIRT3 was remarkably downregulated in HCC cell lines and cancer tissues, we next further examined its expression in 248 paraffin-embedded HCC tissues. According to the results of TMAbased IHC, SIRT3 was mainly presented in cytoplasm (Fig. 3A?F). Out of more than 65 of cases, SIRT3 expressions in HCC were lower than those in corresponding adjacent nontumor tissues. Furthermore, based on the definition of cutoff score, low SIRT3 expression was observed in 67.3 (167/248) of HCC cases.Univariate and Multivariate Analyses of Prognostic Variables in HCC PatientsTo evaluate the representative of our samples, univariate analyses were applied. Results indicated that SIRT3, as well as tumor size, serum AFP level, tumor multiplicity, clinical stage, vascular invasion, tumor differentiation, and relapse, was responsible for outcome of HCC patient who underwent surgical resection (Tables 2 and S1).SIRT3 as a Prognostic Biomarker in HCCFigure 6. Relation of SIRT3 expression with overall survival in morphologic and pathological HCC subgroups. Survival analysis was performed in subgroups according to the factors that are attributed to worse outcome of HCC patients, using Kaplan-Meier survival analysis (log-rank test). doi:10.1371/journal.pone.0051703.gMultiple Cox regression analysis was conducted to determine the independent prognostic value of SIRT3. After adjusted for the prognostic factors established in univariate analysis, a significant correlation of low SIRT3 expression with worse overall survival (Hazard Ratio (HR) 0.555, P = 0.016) was observed (Table 3). However, SIRT3 was revealed not to be an independent marker of recurrence-free survival (Hazard Ratio (HR) 0.712, P = 0.123) for HCC patients (Table S2). Taken together, our data suggested SIRT3 as an independent prognostic biomarker for overall survival in postsurgical patients with primary HCC.DiscussionHCC is a heterogeneous cancer with a very high mortality. Searching for valuable biomarkers for HCC diagnosis and prognostic prediction has been attracting more and more interests. In recent years, many potential biomarkers have been disclosed to be of diagnostic value in HCC, such as serum DKK1 [24], serum anti-Ku86 [25.