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Tumoral LINE-1 hypomethylation is associated with poor survival of patients with intrahepatic cholangiocarcinoma.

ABSTRACT: DNA methylation changes occurring in cancer cells are featured with both promoter CpG island hypermethylation and diffuse genomic hypomethylation. Long interspersed element-1 (LINE-1) is repeated in an interspersed manner with an estimated 500,000 copies per genome. LINE-1 has its CpG sites of the 5' untranslated region methylated heavily in normal cells and undergoes demethylation in association with cancerization. However, little information is available regarding LINE-1 hypomethylation and its prognostic implication in intrahepatic cholangiocarcinomas.A total of 172 cases of intrahepatic cholangiocarcinomas were analyzed for their methylation levels at four CpG sites of LINE-1 using bisulfite pyrosequencing. We examined the relation between tumoral LINE-1 methylation level and clinicopathological features, including survival.Tumor differentiation, lymphatic invasion, and T stage were associated with a low average methylation level of LINE-1 at the four CpG sites; LINE-1 methylation level tended to be lower in high-grade differentiation, lymphatic emboli, and higher T stage. LINE-1 hypomethylation was significantly linked with lower cancer-specific survival in patients with intrahepatic cholangiocarcinoma and was found to be an independent prognostic parameter.Our findings suggest that tumoral LINE-1 hypomethylation could be a molecular biomarker heralding poor prognosis of patients with intrahepatic cholangiocarcinoma. Our findings need to be validated in further study.

SUBMITTER: Jeong S

PROVIDER: S-EPMC5576385 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Tumoral LINE-1 hypomethylation is associated with poor survival of patients with intrahepatic cholangiocarcinoma.

Jeong Seorin S Lee Kyoungbun K Wen Xianyu X Kim Younghoon Y Cho Nam-Yun NY Jang Ja-June JJ Kang Gyeong Hoon GH

BMC cancer 20170829 1

<h4>Background</h4>DNA methylation changes occurring in cancer cells are featured with both promoter CpG island hypermethylation and diffuse genomic hypomethylation. Long interspersed element-1 (LINE-1) is repeated in an interspersed manner with an estimated 500,000 copies per genome. LINE-1 has its CpG sites of the 5' untranslated region methylated heavily in normal cells and undergoes demethylation in association with cancerization. However, little information is available regarding LINE-1 hyp ...[more]

PMID: 28851390

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Project description:Background and purposeCurrently, human papillomavirus (HPV) positivity represents a strong prognostic factor for both reduced risk of relapse and improved survival in patients with oropharyngeal squamous cell carcinoma (OPSCC). However, a subset of HPV-positive OPSCC patients still experience poor outcomes. Furthermore, HPV-negative OPSCC patients, who have an even higher risk of relapse, are still lacking suitable prognostic biomarkers for clinical outcome. Here, we evaluated the prognostic value of LINE-1 methylation level in OPSCC patients and further addressed the relationship between LINE-1 methylation status and p53 protein expression as well as genome-wide/gene-specific DNA methylation.ResultsIn this study, DNA was extracted from 163 formalin-fixed paraffin-embedded tissue samples retrospectively collected from stage III-IVB OPSCC patients managed with curative intent with up-front treatment. Quantitative methylation-specific PCR revealed that LINE-1 hypomethylation was directly associated with poor prognosis (5-year overall survival-OS: 28.1% for LINE-1 methylation < 35% vs. 69.1% for ≥ 55%; p < 0.0001). When LINE-1 methylation was dichotomized as < 55% versus ≥ 55%, interaction with HPV16 emerged: compared with hypermethylated HPV16-positive patients, subjects with hypomethylated HPV16-negative OPSCC reported an adjusted higher risk of death (HR 4.83, 95% CI 2.24-10.38) and progression (HR 4.54, 95% CI 2.18-9.48). Tumor protein p53 (TP53) gene is often mutated and overexpressed in HPV-negative OPSCC. Since p53 has been reported to repress LINE-1 promoter, we then analyzed the association between p53 protein expression and LINE-1 methylation levels. Following p53 immunohistochemistry, results indicated that among HPV16-negative patients with p53 ≥ 50%, LINE-1 methylation levels declined and remained stable at approximately 43%; any HPV16-positive patient reported p53 ≥ 50%. Finally, DNA methylation analysis demonstrated that genome-wide average methylation level at cytosine-phosphate-guanine sites was significantly lower in HPV16-negative OPSCC patients who relapsed within two years. The subsequent integrative analysis of gene expression and DNA methylation identified 20 up-regulated/hypomethylated genes in relapsed patients, and most of them contained LINE-1 elements in their promoter sequences.ConclusionsEvaluation of the methylation level of LINE-1 may help in identifying the subset of OPSCC patients with bad prognosis regardless of their HPV status. Aberrant LINE-1 hypomethylation might occur along with TP53 mutations and lead to altered gene expression in OPSCC.

Project description:PurposeThe role of locoregional therapy compared to systemic chemotherapy (SYS) for unresectable intrahepatic cholangiocarcinoma (IHC) remains controversial. The importance of hepatic disease control, either as initial or salvage therapy, is also unclear. We compared overall survival (OS) in patients treated with resection, hepatic arterial infusion pump (HAIP) chemotherapy, or SYS as it relates to hepatic recurrence or progression. We also evaluated recurrence after resection to determine the efficacy of locoregional salvage therapy.Patients and methodsIn this single-institution retrospective analysis, patients with biopsy-proven IHC treated with either curative-intent resection, HAIP (with or without SYS), or SYS alone were analyzed. Propensity score matching (PSM) was used to compare patients with liver-limited, advanced disease treated with HAIP versus SYS. The impact of locoregional salvage therapies in patients with liver-limited recurrence was analyzed in the resection cohort.ResultsFrom 2000 to 2017, 714 patients with IHC were treated, 219 (30.7%) with resectable disease, 316 (44.3%) with locally advanced disease, and 179 (25.1%) with metastatic disease. Resected patients were less likely to recur or progress in the liver (hazard ratio [HR] 0.41, 95% CI 0.34-0.45) versus those that received HAIP or SYS (HR 0.58, 95% CI 0.50-0.65 vs. HR 0.63, 95% CI 0.57-0.69, respectively). In resected patients, 161 (64.4%) recurred, with 65 liver-only recurrences. Thirty of these patients received subsequent locoregional therapy. On multivariable analysis, locoregional therapy was associated with improved OS after isolated liver recurrence (HR 0.46, 95% CI 0.29-0.75; p = 0.002). In patients with locally advanced unresectable or multifocal liver disease (with or without distant organ metastases), PSM demonstrated improved hepatic progression-free survival in patients treated with HAIP versus SYS (HR 0.65; 95% CI 0.46-0.91; p = 0.01), which correlated with improved OS (HR 0.59, 95% CI 0.43-0.80; p < 0.001).ConclusionIn patients with liver-limited IHC, hepatic disease control is associated with improved OS, emphasizing the potential importance of liver-directed therapy.

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Tumoral LINE-1 hypomethylation is associated with poor survival of patients with intrahepatic cholangiocarcinoma.

Publications

Tumoral LINE-1 hypomethylation is associated with poor survival of patients with intrahepatic cholangiocarcinoma.

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