BACKGROUND: The level of long interspersed nucleotide element-1 (LINE-1) methylation has become regarded as a surrogate marker of global DNA methylation. Previously, we demonstrated that LINE-1 hypomethylation might contribute to the acquisition of aggressive tumor behavior through genomic gains of oncogenes such as cyclin-dependent kinase 6 (CDK6) in esophageal squamous cell carcinoma. However, the relationship between LINE-1 hypomethylation and clinical outcome in hepatocellular carcinoma (HCC) remains unclear. METHODS:LINE-1 methylation level in 208 samples of curatively resected HCCs was measured by pyrosequencing assay, and the prognostic value of LINE-1 methylation level in HCC was examined. RESULTS:LINE-1 methylation levels in the 208 HCC patients investigated were distributed as follows: mean 64.7; median 64.6; standard deviation (SD) 13.6; range 21.5-99.1; interquartile range 62.9-66.6. Univariate Cox regression analysis revealed a significantly higher cancer recurrence rate in the low-methylation-level group than in the high-methylation-level group (hazard ratio 1.58; 95 % CI 1.05-2.47; p = 0.028). Interestingly, the influence of LINE-1 hypomethylation on patient outcome was modified by hepatitis virus infection (p of interaction = 0.023); LINE-1 hypomethylation was associated with a higher cancer recurrence rate in patients without hepatitis virus infection (log-rank p = 0.0047). CDK6 messenger RNA expression levels were inversely associated with LINE-1 methylation levels (p = 0.0075; R = -0.37). CONCLUSIONS: Genome-wide DNA hypomethylation, as measured by LINE-1 levels, might be associated with poor disease-free survival in HCC patients, suggesting a potential role for LINE-1 methylation level as a biomarker for identifying patients who will experience an unfavorable clinical outcome.
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BACKGROUND: The level of long interspersed nucleotide element-1 (LINE-1) methylation has become regarded as a surrogate marker of global DNA methylation. Previously, we demonstrated that LINE-1 hypomethylation might contribute to the acquisition of aggressive tumor behavior through genomic gains of oncogenes such as cyclin-dependent kinase 6 (CDK6) in esophageal squamous cell carcinoma. However, the relationship between LINE-1 hypomethylation and clinical outcome in hepatocellular carcinoma (HCC) remains unclear. METHODS: LINE-1 methylation level in 208 samples of curatively resected HCCs was measured by pyrosequencing assay, and the prognostic value of LINE-1 methylation level in HCC was examined. RESULTS: LINE-1 methylation levels in the 208 HCC patients investigated were distributed as follows: mean 64.7; median 64.6; standard deviation (SD) 13.6; range 21.5-99.1; interquartile range 62.9-66.6. Univariate Cox regression analysis revealed a significantly higher cancer recurrence rate in the low-methylation-level group than in the high-methylation-level group (hazard ratio 1.58; 95 % CI 1.05-2.47; p = 0.028). Interestingly, the influence of LINE-1 hypomethylation on patient outcome was modified by hepatitis virus infection (p of interaction = 0.023); LINE-1 hypomethylation was associated with a higher cancer recurrence rate in patients without hepatitis virus infection (log-rank p = 0.0047). CDK6 messenger RNA expression levels were inversely associated with LINE-1 methylation levels (p = 0.0075; R = -0.37). CONCLUSIONS: Genome-wide DNA hypomethylation, as measured by LINE-1 levels, might be associated with poor disease-free survival in HCC patients, suggesting a potential role for LINE-1 methylation level as a biomarker for identifying patients who will experience an unfavorable clinical outcome.
Authors: Chih-Ching Yeh; Abhishek Goyal; Jing Shen; Hui-Chen Wu; Joshua A Strauss; Qiao Wang; Irina Gurvich; Rachael A Safyan; Gulam A Manji; Mary V Gamble; Abby B Siegel; Regina M Santella Journal: Ann Surg Oncol Date: 2017-06-07 Impact factor: 5.344