Project description:We will explore the genetic (including APC, k-ras, p53, MSI, etc.) and environmental (including family history, life style, diet, nutritional status, DM, serum IGF-I, IGFBP-3, etc.) risk factors of colorectal tumorigenesis. We will accrue approximately 1000 patients as experimental group. The control group consists of 2000 individuals who were confirmed without colorectal cancer or polyps by colonoscopy. We estimated the statistical power of this study will reach more than 90%. In the second year, we will explore the association between various environmental risk factors with the epigenetic changes of various oncogenes and tumor suppressor genes. Firstly, we will study the correlation between hypermethylation of promoter region of hMLH1 gene with various environmental factors. Next, we will explore the genetic polymorphisms of promoter of E-cadherin gene. Recently, it has been reported that the C→A genetic polymorphism in the promoter region of E-cadherin gene in prostate cancer. Since this phenomenon has not been reported in colorectal cancer, it is mandatory for us to extend our research to the E-cadherin polymorphisms of colorectal cancer. Moreover, this project will focus on exploration of the association between the genetic polymorphisms of promoter of TS gene with chemosensitivity to 5-Fu-based therapy. We speculated that the better prognosis in colorectal tumors with MSI is related to their expression of TS gene. In summary, the second year of this project will extend our accumulated experience in the study of genetic polymorphisms to further clarify the association between genetic polymorphisms of TS gene with the prognosis of colorectal cancers after chemotherapy. We believe that this project will facilitate: (1) the further clarification of colorectal cancer tumorigenesis; (2) the establishment of domestic epidemiological data of colorectal cancer of Taiwan, and (3) the improvement of the quality of clinical management of patients with colorectal cancer.
Project description:The enhancer/promoter of the vitellogenin II (VTG) gene has been extensively studied as a model system of vertebrate transcriptional control. While deletion mutagenesis and in vivo footprinting identified the transcription factor (TF) binding sites governing its tissue specificity, DNase hypersensitivity- and DNA methylation studies revealed the epigenetic changes accompanying its hormone-dependent activation. Moreover, upon induction with estrogen (E2), the region flanking the estrogen-responsive element (ERE) was reported to undergo active DNA demethylation. We now show that although the VTG ERE is methylated in embryonic chicken liver and in LMH/2A hepatocytes, its induction by E2 was not accompanied by extensive demethylation. In contrast, E2 failed to activate a VTG enhancer/promoter-controlled luciferase reporter gene methylated by SssI. Surprisingly, this inducibility difference could be traced not to the ERE, but rather to a single CpG in an E-box (CACGTG) sequence upstream of the VTG TATA box, which is unmethylated in vivo, but methylated by SssI. We demonstrate that this E-box binds the upstream stimulating factor USF1/2. Selective methylation of the CpG within this binding site with an E-box-specific DNA methyltranferase Eco72IM was sufficient to attenuate USF1/2 binding in vitro and abolish the hormone-induced transcription of the VTG gene in the reporter system.
Project description:Purpose: To identify the genetic basis of posterior polymorphous corneal dystrophy 1 (PPCD1). Methods: Next-generation sequencing was performed on DNA samples from 4 affected and 4 unaffected members of a previously reported family with PPCD1 linked to chromosome 20 between D20S182 and D20S195. Custom capture probes were utilized for targeted region capture of the linked interval. Single nucleotide variants (SNVs) and insertions/deletions (indels) were identified using two bioinformatics pipelines and two annotation databases. Candidate variants met the following criteria: quality score ≥20, read depth ≥5X, heterozygous, novel or rare (minor allele frequency (MAF) ≤ 0.05), present in each affected individual and absent in each unaffected individual. Structural variants were detected with two different microarray platforms to identify indels of varying sizes. Results: Sequencing reads aligned to the linked region on chromosome 20, and high coverage was obtained across the sequenced region. The majority of identified variants were detected with both pipelines and annotation databases, although unique variants were identified. Twelve SNVs in 10 genes (2 synonymous variants and 10 noncoding variants) and 9 indels in 7 genes met the filtering criteria and were considered candidate variants for PPCD1. Conclusions: Next-generation sequencing of the PPCD1 interval has identified 17 genes containing novel or rare SNVs and indels that segregate with the affected phenotype in an affected family previously mapped to the PPCD1 locus. We anticipate that screening of these candidate genes in other families previously mapped to the PPCD1 locus will result in the identification of the genetic basis of PPCD1.