Prediction of smoking by multiplex bisulfite PCR with long amplicons considering allele-specific effects on DNA methylation
CLINICAL EPIGENETICS
Authors: Kondratyev, Nikolay; Golov, Arkady; Alfimova, Margarita; Lezheiko, Tatiana; Golimbet, Vera
Abstract
BackgroundMethylation of DNA is associated with a variety of biological processes. With whole-genome studies of DNA methylation, it became possible to determine a set of genomic sites where DNA methylation is associated with a specific phenotype. A method is needed that allows detailed follow-up studies of the sites, including taking into account genetic information. Bisulfite PCR is a natural choice for this kind of task, but multiplexing is one of the most important problems impeding its implementation. To address this task, we took advantage of a recently published method based on Pacbio sequencing of long bisulfite PCR products (single-molecule real-time bisulfite sequencing, SMRT-BS) and tested the validity of the improved methodology with a smoking phenotype.ResultsHerein, we describe the panhandle modification of the method, which permits a more robust PCR with multiple targets. We applied this technique to determine smoking by DNA methylation in 71 healthy people and 83 schizophrenia patients (n=50 smokers and n=104 non-smokers, Russians of the Moscow region). We used five targets known to be influenced by smoking (regions of genes AHRR, ALPPL2, IER3, GNG12, and GFI1). We discovered significant allele-specific methylation effects in the AHRR and IER3 regions and assessed how this information could be exploited to improve the prediction of smoking based on the collected DNA methylation data. We found no significant difference in the methylation profiles of selected targets in relation to schizophrenia suggesting that smoking affects methylation at the studied genomic sites in healthy people and schizophrenia patients in a similar way.ConclusionsWe determined that SMRT-BS with panhandle modification performs well in the described setting. Additional information regarding methylation and allele-specific effects could improve the predictive accuracy of DNA methylation-based models, which could be valuable for both basic research and clinical applications.
ALPPL2 Is a Potential Diagnostic Biomarker for Pancreatic Cancer-Derived Extracellular Vesicles
MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT
Authors: Shin, Hye-Su; Jung, Sang Baek; Park, Sungho; Dua, Pooja; Lee, Dong Ki
Abstract
Pancreatic cancer is an aggressive malignancy that often goes undiagnosed in the early stages. Non-invasive, early, and accurate diagnosis is therefore undoubtedly the "holy grail" of pancreatic cancer research. However, despite extensive research efforts, there is no definitive biomarker for this cancer. Previously, we identified alkaline phosphatase placental-like 2 (ALPPL2) as a diagnostic biomarker for pancreatic ductal adenocarcinoma and developed a 20-fluoro modified RNA aptamer toward it. In this study, we show that ALPPL2 is present in pancreatic cancer extracellular vesicles (EVs) and therefore has potential application in liquid biopsy-based diagnostic strategies. We also developed ALPPL2 direct and sandwich aptamer-linked immobilized sorbent assay (ALISA) for EVs, which could sensitively and specifically detect the protein. We believe that our ALISA format may have a potential diagnostic utility in screening pancreatic-cancer-derived EVs.