Copy Number Aberrations of Multiple Genes Identified as Prognostic Markers for Extrahepatic Metastasis-free Survival of Patients with Hepatocellular Carcinoma

Extrahepatic metastasis confers unfavorable patient prognosis in patients with hepatocellular carcinoma(HCC),however,reliable markers allowing prediction of extrahepatic metastasis at the time of initial diagnosis are still lacking.This study was to identify gene-level copy number aberrations(CNAs)related to extrahepatic metastasis-free survival of HCC patients,and further examine the associations between CNAs and gene expression.Array comparative genomic hybridization(aCGH)and expression array were used to analyze gene CNAs and expression levels,respectively.The associations between CNAs of a panel of 20 genes and extrahepatic metastasis-free survival were analyzed in 66 patients with follow-up period of 1.6-90.5 months.The gene expression levels between HCCs with and without gene CNA were compared in 109 patients with HCC.We observed that gains at MDM4 and BCL2L1,and losses at APC and FBXW7 were independent prognostic markers for extrahepatic metastasis-free survival of HCC patients.Integration analysis of aCGH and expression data showed that MDM4 and BCL2L1 were significantly upregulated in HCCs with gene gain,while APC and FBXW7 were significantly downregulated in HCCs with gene loss.We concluded that gene gains at MDM4 and BCL2L1,and losses at APC and FBXW7,with concordant expression changes,were associated with extrahepatic metastasis-free survival of HCC patients and have potential to act as novel prognostic markers.

Association of p53 codon 72 polymorphism with liver metastases of colorectal cancers positive for p53 overexpression

Objective： To evaluate the association between p53 codon 72 polymorphism （R72P） and the risk ofcolorectal liver metastases. Methods： The p53 R72P genotype was identified by polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method in 78 consecutive colorectal cancer patients with liver metastases and 214 age- and sex-matched cases with nonmetastatic colorectal cancer. Results： The R allele of the p53 R72P polymorphism was more frequently found in metastatic cases than in nonmetastatic cases （P=0.075）. Carriers of the 72R allele had a 2.25-fold （95% CI （confidence interval）=1.05-4.83） increased risk of liver metastases. On the stratification analysis, 72R-carrying genotype conferred a 3.46-fold （95% CI=1.02-11.72） and a 1.05-fold （95% CI=0.36-3.08） increased risk of liver metastases for p53 overexpression-positive and negative colorectal cancers, respectively. Conclusion： These results demonstrate for the first time that the 72R allele of the p53 polymorphism has an increased risk for liver metastases in colorectal cancers positive for p53 overexpression.

A Panel of Genes Identified as Targets for 8q24.13-24.3 Gain Contributing to Unfavorable Overall Survival in Patients with Hepatocellular Carcinoma

Copy number aberrations （CNAs） in chromosome arm 8q have been associated with unfavorable clinical outcomes of several cancers and progressive tumor characteristics of hepatocellular carcinoma （HCC）. This study was to identify correlation of CNAs in 8q with clinical outcomes of HCC patients, and further screen for differentially expressed genes in outcome-related CNAs. Array comparative genomic hybridization and expression arrays were performed to detect CNAs and expression levels, respectively. The correlations between CNAs in 8q and outcomes were analyzed in 66 patients, with a median follow-up time of 45.0 months （range, 2.6-108.6 months）. One hundred and nine cases were further evaluated to identify differentially expressed genes in the potential outcome-related CNAs. Copy number gain in 8q was observed in 22 （33.3%） of the 66 HCC cases. The most recurrent gains （with frequencies 〉20%） were 8q 13.3-21.3, 8q21.3-23.3, 8q23.3-24.13, 8q24.13-24.3, and 8q24.3. Survival analysis showed that 8q24.13-24.3 gain was significantly associated with reduced overall survival （P=0.010）. Multivariate Cox analysis identified 8q24.13- 24.3 gain as an independent prognostic factor for poor overall survival （HR=2.47; 95% CI=1.16-5.26; P=0.019）. A panel of 17 genes within the 8q24.13-24.3 region, including ATAD2, SQLE, PVT1, ASAP1, and NDRG1 were significantly upregulated in HCCs with 8q24.13-24.3 gain compared to those without. These results suggest that copy number gain at 8q24.13-24.3 is an unfavorable prognostic marker for HCC patients, and the potential oncogenes ATAD2, SQLE, PVT1, ASAP1, and NDRG1 within the regional gain, may contribute coordinately to the 8q24.13-24.3 gain-related poor prognosis.

Association of hypomethylation of LINE-1 repetitive element in blood leukocyte DNA with an increased risk of hepatocellular carcinoma

Global DNA hypomethylation has been associated with increased risk for cancers of the colorectum,bladder,breast,head and neck,and testicular germ cells.The aim of this study was to examine whether global hypomethylation in blood leukocyte DNA is associated with the risk of hepatocellular carcinoma (HCC).A total of 315 HCC cases and 356 age-,sex-and HBsAg status-matched controls were included.Global methylation in blood leukocyte DNA was estimated by analyzing long interspersed element-1 (LINE-1) repeats using bisulfite-polymerase chain reaction (PCR) and pyrosequencing.We observed that the median methylation level in HCC cases (percentage of 5-methylcytosine (5mC)=77.7%) was significantly lower than that in controls (79.5% 5mC) (P=0.004,Wilcoxon rank-sum test).The odds ratios (ORs) of HCC for individuals in the third,second,and first (lowest) quartiles of LINE-1 methylation were 1.1 (95% confidence interval (CI) 0.7-1.8),1.4 (95% CI 0.8-2.2),and 2.6 (95% CI 1.7-4.1) (P for trend <0.001),respectively,compared to individuals in the fourth (highest) quartile.A 1.9-fold (95% CI 1.4-2.6) increased risk of HCC was observed among individuals with LINE-1 methylation below the median compared to individuals with higher (>median) LINE-1 methylation.Our results demonstrate for the first time that individuals with global hypomethylation measured in LINE-1 repeats in blood leukocyte DNA have an increased risk for HCC.Our data provide the evidence that global hypomethylation detected in the easily obtainable DNA source of blood leukocytes may help identify individuals at risk of HCC.