Sitong Chen

Impact of the Location of CpG Methylation within the GSTP1 Gene on Its Specificity as a DNA Marker for Hepatocellular Carcinoma

Hypermethylation of the glutathione S-transferase π 1 (GSTP1) gene promoter region has been reported to be a potential biomarker to distinguish hepatocellular carcinoma (HCC) from other liver diseases. However, reports regarding how specific a marker it is have ranged from 100% to 0%. We hypothesized that, to a large extent, the variation of specificity depends on the location of the CpG sites analyzed. To test this hypothesis, we compared the methylation status of the GSTP1 promoter region of the DNA isolated from HCC, cirrhosis, hepatitis, and normal liver tissues by bisulfite–PCR sequencing. We found that the 5′ region of the position −48 nt from the transcription start site of the GSTP1 gene is selectively methylated in HCC, whereas the 3′ region is methylated in all liver tissues examined, including normal liver and the HCC tissue. Interestingly, when DNA derived from fetal liver and 11 nonhepatic normal tissue was also examined by bisulfite-PCR sequencing, we found that methylation of the 3′ region of the promoter appeared to be liver-specific. A methylation-specific PCR assay targeting the 5′ region of the promoter was developed and used to quantify the methylated GSTP1 gene in various diseased liver tissues including HCC. When we used an assay targeting the 3′ region, we found that the methylation of the 5′-end of the GSTP1 promoter was significantly more specific than that of the 3′-end (97.1% vs. 60%, p<0.0001 by Fishers exact test) for distinguishing HCC (n = 120) from hepatitis (n = 35) and cirrhosis (n = 35). Encouragingly, 33.8% of the AFP-negative HCC contained the methylated GSTP1 gene. This study clearly demonstrates the importance of the location of CpG site methylation for HCC specificity and how liver-specific DNA methylation should be considered when an epigenetic DNA marker is studied for detection of HCC.

Comprehensive DNA methylation analysis of hepatitis B virus genome in infected liver tissues

Hepatitis B virus (HBV) is a hepatotropic virus causing hepatitis, cirrhosis and hepatocellular carcinoma (HCC). The methylation status of the HBV DNA in its different forms can potentially provide insight into the pathogenesis of HBV-related liver diseases, including HCC, however this is unclear. The goal of this study is to obtain comprehensive DNA methylation profiles of the three putative CpG islands in the HBV DNA in infected livers, with respect to liver disease progression. The extent of methylation in these CpG islands was first assessed using bisulfite PCR sequencing with a small set of tissue samples, followed by analysis using both quantitative bisulfite-specific PCR and quantitative methylation-specific PCR assays in a larger sample size (n = 116). The level of HBV CpG island 3 methylation significantly correlated with hepatocarcinogenesis. We also obtained, for the first time, evidence of rare, non-CpG methylation in CpG island 2 of the HBV genome in infected liver. Comparing methylation of the HBV genome to three known HCC-associated host genes, APC, GSTP1, and RASSF1A, we did not identify a significant correlation between these two groups.

Abstract 888: Development of a urine DNA based marker panel for early detection of liver cancer

Hepatocellular carcinoma (HCC) or liver cancer is an aggressive disease and one of the fastest growing cancers in incidence in the United States. The 5 year survival rate drops dramatically from a poor 26% in early stages to a mere 2% in later stages of the disease. Currently, the only available biomarker for early detection is serum alpha-fetoprotein which can identify only 40-60% of cases. We aim to improve the poor disease prognosis by developing a screening test capable of detecting liver cancer in its earlier stages. Since cancer is a disease of the genome and epigenome, if we can detect these underlying genetic mutations and epigenetic modifications in the periphery, we should be able to effectively detect cancer early. We have previously shown that urine contains fragmented, cell-free, cancer related DNA, both mutated and methylated, derived from the circulation of cancer patients. We have also demonstrated that the concentration of tumor-derived DNA in plasma and in urine is similar in patients with tumors. Hence, we propose the use of a panel of HCC-associated genetic and epigenetic methylation DNA biomarkers to develop a sensitive, noninvasive urine screening test for HCC. In order to detect these markers in the circulation derived urine DNA, we developed short amplicon (∼50 bp) PCR based assays targeting HCC-associated mutations in TP53, CTNNB1, hTERT genes and HCC associated methylation in GSTP1, RASSF1A and CDKN2A. Urine DNA isolated from hepatitis, cirrhosis and HCC patients were tested in each of the assays and analyzed. Panel performance parameters such as sensitivity, specificity and area under the receiver operating curve were calculated for individual markers and then as a group in order to evaluate their ability to distinguish HCC patients from hepatitis and cirrhosis subjects. The potential of this urine test in the early detection of HCC is discussed. Citation Format: Sitong Chen, Surbhi Jain, Selena Lin, Ying-Hsiu Su, Wei Song. Development of a urine DNA based marker panel for early detection of liver cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 888. doi:10.1158/1538-7445.AM2014-888

Abstract 3128: Detection of genetic and epigenetic DNA markers in urine for the early detection of primary and recurrent HCC

The purpose of this study was to explore the potential of urine DNA biomarkers for the early detection of primary and recurrent hepatocellular carcinoma (HCC). HCC is an aggressive disease with a 5-year survival rate of 26% in early-stage cancers, and a mere 2% in later stages, with an approximate 50% recurrence rate in the first 2 years of treatment. The most commonly used screening biomarker for HCC is serum alpha-fetoprotein (AFP), which detects only 40-60% of cases. We have previously shown that urine contains fragmented, circulation-derived, cell-free DNA that can be used for detection of cancer-related DNA markers, if a tumor is present. In order to detect circulation-derived, cell-free DNA markers in urine, we have developed short amplicon (∼50 bp) PCR-based assays for the three most frequent hotspot mutations in TP53 (codon 249), TERT (-124, promoter), and CTNNB1 (hotspot in exon 3, codons 32-37), and for aberrant DNA methylation in GSTP1 (mGSTP1) and RASSF1A (mRASSF1A). This five marker panel has an area under the receiver operating curve of 0.94 (92.2% sensitivity at 80% specificity) in distinguishing primary HCC (n = 77) from non-HCC (n = 91) patients by a logistic regression-based combination algorithm. Furthermore, these 5 DNA markers scored 42 of the 45 (93.3%) AFP-negative ( Citation Format: Surbhi Jain, Hie-Won Hann, Sitong Chen, Selena Y. Lin, Ting-Tsung Chang, Chi-Tan Hu, Wei Song, Ying-Hsiu Su. Detection of genetic and epigenetic DNA markers in urine for the early detection of primary and recurrent HCC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3128.

Abstract 1569: Development of a noninvasive and sensitive urine screening test for liver cancer targeting circulation-derived cancer DNA biomarkers

Hepatocellular carcinoma (HCC), or liver cancer, is an aggressive disease and is regarded as one of the fastest growing cancers in the United States in incidence. The 5-year survival rate of HCC patients drops dramatically from a poor 26%, in early-stage cancer, to a mere 2% in late stages of this disease. The only available early detection biomarker is serum alpha-fetoprotein, which can detect only 40-60% of cases. Our goal is to develop a screening test for early detection of liver cancer, in order to meet this urgent need for new and better biomarkers for HCC. Cancer is a disease of the genome and epigenome, and if we can detect these underlying genetic mutations and epigenetic modifications in the periphery, we can effectively detect cancer early. Hence, we chose a panel of both HCC-associated genetic and DNA methylation biomarkers. We have previously shown that urine contains fragmented cell-free DNA derived from the circulation and that we can detect cancer-related DNA, both mutated and methylated DNA, in the urine of such patients. We have also demonstrated that the concentration of tumor-derived DNA in plasma and in urine is similar in patients with tumors. In order to demonstrate the feasibility of detecting HCC DNA biomarkers in the circulation derived urine DNA, we have developed short amplicon (∼50 bp) PCR-based assays targeting HCC-specific mutations in TP53 and CTNNB1 genes and HCC-specific methylation in GSTP1, RASSF1A and CDKN2A genes. Urine DNA isolated from samples of hepatitis, cirrhosis, and HCC patients were tested in each of the assays and analyzed for individual marker and panel performance. The performance of the markers and our approach towards the development of a targeted next generation urine DNA based HCC screening test is discussed. Citation Format: Surbhi Jain, Sitong Chen, Selena Y. Lin, Adam Clemens, Hei-won L. Hann, Ting-Tsung Chang, Chi-Tan Hu, Shun-Hua Chen, Wei Song, Ying-Hsiu Su. Development of a noninvasive and sensitive urine screening test for liver cancer targeting circulation-derived cancer DNA biomarkers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1569. doi:10.1158/1538-7445.AM2015-1569

Abstract 1373: Comprehensive analysis of HBV DNA methylation in liver tissues of hepatitis B, cirrhosis and hepatocellular carcinoma patients

Hepatitis B virus (HBV) is a hepatotropic virus causing hepatitis, cirrhosis and hepatocellular carcinoma. In patients, HBV DNA circulates in blood as virion DNA and exists in hepatocytes both as nuclear form (episomal cccDNA and integrated DNA) and as cytoplasmic core DNA form. It has been reported that HBV infection up-regulates DNMTs and thus induces epigenetic changes in the host cells. Understanding the methylation status of the HBV DNA in its different forms can potentially provide insight into the pathogenesis of HBV-related liver diseases including hepatocarcinogenesis. Previous studies conducted in patient serum and in cell cultures have demonstrated that the CpG islands of HBV virion DNA are in the unmethylated state, and cccDNA methylation has been extensively studied for its role in the regulation of transcription, but very few studies have investigated the methylation status of integrated HBV DNA in human liver tissues. To better understand the methylation status of HBV DNA in hepatitis B, cirrhosis and HCC, a comprehensive methylation profile of three CpG islands in the HBV genome was assessed by BS-sequencing, and methylation of each of the 3 CpG islands was compared by using bisulfite specific PCR and methylation specific PCR assays in a larger sample size. We observed that the methylation of CpG island 1 and 3 of HBV DNA from liver tissues was significantly higher in HCC as compared to hepatitis and cirrhosis. We also obtained, for the first time, the evidence of rare non-CpG methylation in the CpG island 1 and 2 of HBV genome in liver tissues. The overall co-relation of HBV genome methylation and disease progression was also investigated. In addition, no co-relation between the methylation levels of the HBV genome and host genome was found, suggesting independent mechanisms regulate the methylation of host and viral genomes. The mechanisms of HBV genome methylation in liver disease and its regulation are discussed. Citation Format: Surbhi Jain, Sitong Chen, Batbold Boldbaatar, Selena Y. Lin, Ran Yan, Chi-Tan Hu, Haitao Guo, Timothy M. Block, Wei song, Ying-Hsiu Su. Comprehensive analysis of HBV DNA methylation in liver tissues of hepatitis B, cirrhosis and hepatocellular carcinoma patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1373. doi:10.1158/1538-7445.AM2014-1373

Abstract 4086: Location matters: The impact of the location of CpG sites on the specificity of methylation biomarkers for HCC

Hepatocellular carcinoma (HCC) is the second fastest growing cancer and one of the top 10 causes of cancer deaths in the United States. The 5-year survival rate is 14%, ranging from 26% among early stage tumors to only 2% in late stage HCC. The only available biomarker for screening, serum alpha-fetoprotein (AFP), has a low sensitivity of detection (40%-60%), so the need for a better detection method is urgent. Given the heterogeneous nature of HCC, a panel of genetic and epigenetic biomarkers would be needed to obtain high sensitivity for the early diagnosis of HCC. In the course of assembling a panel of epigenetic markers for HCC, we noticed variable HCC specificity of three extensively studied potential methylation biomarkers, APC, GSTP1, and RASSF1A. We hypothesized that the specificity of promoter methylation of the tumor suppressor genes APC, GSTP1, and RASSF1A as a biomarker for HCC could depend upon the location of the CpG sites analyzed. To test this hypothesis, we used bisulfite-PCR sequencing to compare the methylation status of the promoter region of these three genes in DNA isolated from HCC, matched adjacent non-HCC, cirrhosis, hepatitis, and normal liver. We identified HCC-specific CpG methylation sites and unique liver-specific methylation patterns in the promoter region of the APC (Jain et. al, PloSOne 2011) and GSTP1 genes and in a more HCC-specific promoter region (p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4086. doi:1538-7445.AM2012-4086