Preparation Of Human Genomic CpG Islands Library And Construction And Application Of Inhibitor-controlled PCR

BackgroundsCpG islands (CGIs) of human genome are GC rich fragments located mainly in the promoter regions, and linked with ~60% of human genes. CGIs are unmethylated in human normal cells, with the exception of those that are associated with imprinted genes and genes on the inactive X chromosome. Hypermethylation of CGIs is a common event in carcinogenesis. Methylation of promoter CGIs is associated with a closed chromatin structure and transcriptional silencing of the associated gene, especially for tumor suppressor gene. The transcriptional silencing of tumor suppressor genes by promoter CGI hypermethylation contributes to oncogenesis. Compared with normal cells, tumor cells sustain tumor-specific methylation status and patterns of promoter CGIs. Tumor-specific CGIs methylation status and patterns are early events in carcinogenesis that could occur before the morphologic changes. Epigenetic biomarkers based on tumor-specific changes of CGIs methylation status and patterns have been considered helpful to the epigenetic diagnosis and therapeutic monitoring. So far, isolation and enrichment of CGIs at genomic levels play an important role in the evaluation of global CGIs methylation status and patterns.Polymerase chain reaction (PCR) is a general molecular biologic technique used in clinic and scientific researches. A common limitation to PCR-based methods is failed amplification due to the presence of PCR-inhibitory substances in the samples. Because of the universality and heterogeneous of samples from clinic and scientific researches, it can not always avoid the PCR-inhibitor substances that could be contained in these samples. If the PCR-inhibitor substances contained in samples are not diminished or eliminated, there should be false negative results. Inhibitor-controlled PCR (IC-PCR), which used internal...