Selena Y. Lin

Rapid and sensitive detection of hepatitis B virus 1762T/1764A double mutation from hepatocellular carcinomas using LNA-mediated PCR clamping and hybridization probes

The 1762T/1764A double mutation of the hepatitis B virus (HBV) basal core promoter has been suggested to be a potential biomarker for hepatocellular carcinoma (HCC) among individuals with chronic HBV infection. In this study, a real-time PCR assay is established using the hybridization probes and an oligonucleotide clamp containing locked nucleic acids (LNAs). The LNA-containing oligonucleotide clamp specific for the wild type HBV is able to suppress the amplification of the wild type HBV templates. In addition, the clamp can inhibit the binding of the WT templates to the fluorescence probes thereby suppress the wild type HBV signals during the melting curve analyses. These effects facilitated the detection of HBV double mutation in the presence of 3000-fold excess of the wild type genome. Thus PCR amplification coupled with the melting curve analyses provides a quick, simple, and highly sensitive tool for the detection of this HBV double mutation.

Methylation of the CpG Sites Only on the Sense Strand of the APC Gene Is Specific for Hepatocellular Carcinoma

Hypermethylation of the promoter of the tumor suppressor gene, adenomatous polyposis coli (APC), occurs in various malignancies, including hepatocellular carcinoma (HCC). However, reports on the specificity of the methylation of the APC gene for HCC have varied. To gain insight into how these variations occur, bisulfite PCR sequencing was performed to analyze the methylation status of both sense and antisense strands of the APC gene in samples of HCC tissue, matched adjacent non-HCC liver tissue, hepatitis, cirrhosis, and normal liver tissues. DNA derived from fetal liver and 12 nonhepatic normal tissue was also examined. These experiments revealed liver-specific, antisense strand-biased CpG methylation of the APC gene and suggested that, although methylation of the antisense strand of the APC gene exists in normal liver and other non-HCC disease liver tissue, methylation of the sense strand of the APC gene occurs predominantly in HCC. To determine the effect of the DNA strand on the specificity of the methylated APC gene as a biomarker for HCC detection, quantitative methylation-specific PCR assays for sense and antisense strand DNA were developed and performed on DNA isolated from HCC (n = 58), matched adjacent non-HCC (n = 58), cirrhosis (n = 41), and hepatitis (n = 39). Receiver operating characteristic curves were constructed. With the cutoff value set at the limit of detection, the specificity of sense and antisense strand methylation was 84% and 43%, respectively, and sensitivity was 67.2% and 72.4%, respectively. This result demonstrated that the identity of the methylated DNA strand impacted the specificity of APC for HCC detection. Interestingly, methylation of the sense strand of APC occurred in 40% of HCCs from patients with serum AFP levels less than 20 ng/mL, suggesting a potential role for APC as a biomarker to complement AFP in HCC screening.

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.

A Locked Nucleic Acid Clamp-Mediated PCR Assay for Detection of a p53 Codon 249 Hotspot Mutation in Urine

Hepatocellular carcinoma (HCC) has a 5-year survival rate of <10% because it is difficult to diagnose early. Mutations in the TP53 gene are associated with approximately 50% of human cancers. A hotspot mutation, a G:C to T:A transversion at codon 249 (249T), may be a potential DNA marker for HCC screening because of its exclusive presence in HCC and its detection in the circulation of some patients with HCC. A locked nucleic acid clamp-mediated PCR assay, followed by melting curve analysis (using the SimpleProbe), was developed to detect the TP53 249T mutation. In this assay, the locked nucleic acid clamp suppressed 10(7) copies of wild-type templates and permitted detection of 249T-mutated template, with a sensitivity of 0.1% (1:1000) of the mutant/wild-type ratio, assessed by a reconstituted standard within 2 hours. With an amplicon size of 41 bp, it detects target DNA sequences in short fragmented DNA templates. The detected mutations were validated by DNA sequencing analysis. We then tested DNA isolated from urine samples of patients with HCC for p53 mutations and identified positive TP53 mutations in 9 of 17 samples. The possibility of using this novel TP53 249T assay to develop a urine or blood test for HCC screening is discussed.

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.

Differential methylation of the promoter and first exon of the RASSF1A gene in hepatocarcinogenesis

Aberrant methylation of the promoter, P2, and the first exon, E1, regions of the tumor suppressor gene RASSF1A, have been associated with hepatocellular carcinoma (HCC), albeit with poor specificity. This study analyzed the methylation profiles of P1, P2 and E1 regions of the gene to identify the region of which methylation most specifically corresponds to HCC and to evaluate the potential of this methylated region as a biomarker in urine for HCC screening.

DNA markers in molecular diagnostics for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the one of the leading causes of cancer mortality in the world, mainly due to the difficulty of early detection and limited therapeutic options. The implementation of HCC surveillance programs in well-defined, high-risk populations were only able to detect about 40–50% of HCC at curative stages (Barcelona Clinic Liver Cancer stages 0 & 1) due to the low sensitivities of the current screening methods. The advance of sequencing technologies has identified numerous modifications as potential candidate DNA markers for diagnosis/surveillance. Here we aim to provide an overview of the DNA alterations that result in activation of cancer pathways known to potentially drive HCC carcinogenesis and to summarize performance characteristics of each DNA marker in the periphery (blood or urine) for HCC screening.

Strategic Assay Developments for Detection of HBV 1762T/1764A Double Mutation in Urine of Patients with HBV-Associated Hepatocellular Carcinomas

Hepatocellular carcinoma (HCC) is the 7th most common cancer worldwide and remains the third leading cause of cancer deaths (Yang and Roberts 2010). It has a 5-year survival rate of less than 11% even in developed nations (Garcia, Jemal et al. 2007). The 5-year survival rate drops from 26% to 2% in patients with localized versus metastasized cancer (ACS, 2010). The poor prognosis is due mainly to late detection with the methods currently available. Thus, a better screening method to detect HCC at its early, curative stage is needed to improve its outcome. One of the major etiological factors associated with HCC development is chronic infection with hepatitis B virus (HBV). In developing countries, 59% of liver cancers are attributable to HBV and, in developed countries, 23% of liver cancers are attributable to HBV (Garcia, Jemal et al. 2007).

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