[Effect of adenomatous polyposis coli(APC) promoter methylation on gene transcription in lung cancer cell lines].
ABSTRACT Hypermethylation of CpG islands in adenomatous polyposis coli (APC) gene has been detected in a variety of human tumors, which is involved in the pathogenesis of these tumors. In previous research, we detected APC promoter methylation in 47% lung tumor tissues. This study was to analyze the effect of APC promoter methylation on the gene transcription in 3 lung cancer cell lines.
The methylation status of APC promoter 1A in lung adenocarcinoma cell line SPCA1, small cell lung cancer cell line NCI-H446, and big cell lung cancer cell line NCI-H460 was detected by methylation-specific polymerase chain reaction (MSP) and microarray methylated cord blood DNA served as positive control, and unmethylated cord blood DNA served as negative control. The expression of APC was examined by real-time quantitative polymerase chain reaction (PCR) with Sybr-Green I staining. After treatment of 1, 5, 10, 15 micromol/L DNA methyltransferase inhibitor 5-aza-2-deoxycytidine (5-aza-dC), the expression of APC in NCI-H460 cells was detected by real-time PCR.
APC promoter 1A was methylated in NCI-H460 cells, and unmethylated in NCI-H446 and SPC-A1 cells. Hypermethylation was detected in all 5 CpG islands (687, 707, 714, 719, 726) of APC promoter 1A in NCI-H460 cells. The expression of APC in NCI-H460 cells was decreased by 26.04% of that in NCI-H446 cells and by 32.36% of that in SPCA1 cells. After treatment of 1, 5, 10, 15 micromol/L 5-aza-dC, the expression of APC promoter 1A in NCI-H460 cells was enhanced by 4.59, 5.78, 9.58, 5.98 folds, respectively.
APC gene is hypermethylated in HCI-H460 cells, and its transcription coud be activated by 5-aza-dC.
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ABSTRACT: Inactivation of tumor-suppressor gene (TSG) by promoter hypermethylation has been reported in many tumor types, including lung cancer. This study was designed to determine the methylated APC and RASSF1A genes in tumor tissue, serum and plasma of patients with early stage lung cancer. Eighty-nine patients with undetermined solitary pulmonary nodules detected upon CT-scan were recruited in this study. DNA samples were extracted from biopsy tissues, serum and plasma and QMSP of APC and RASSF1A was carried out after bisulfite conversion. The 89 patients consist of 58 stage I lung cancer patients and 31 benign lung disease according to pathological report. Twenty-six cancer patients had matched biopsy tumor tissue, serum and plasma samples. The methylation rates of APC and RASSF1A were 59.0% and 66.1% in biopsy tissues, 42.5% and 52.5% in serum, and 24.1% and 43.1% in plasma of cancer patients. For RASSF1A, different samples all showed a significant difference between cancer group and benign group (P<0.05). However, APC gene only explored the P value less than 0.05 in plasma result. Towards the 26 lung cancer patients with three matched samples, methylation rate in each sample type was more than 50.0% and displayed no difference. Evaluation of APC and RASSF1A promoter methylation by using QMSP appears to be very useful for the differential diagnosis of patients with undetermined solitary pulmonary nodules. Our results also suggested that plasma might be the best sample for clinical detection of early stage lung.03/2015; 7(3):422-32. DOI:10.3978/j.issn.2072-1439.2015.01.24
Article: SNP model to address cytosine trios[Show abstract] [Hide abstract]
ABSTRACT: DNA methylation maintains allele specific gene expression (Chan et al., 2003) in which miRNA influences allele-specific protein expression and SNPs, found inside miRNA, in turn influences tumor susceptibility (Nicoloso et al., 2010). Further, methylated CpGs have been correlated to APC gene in colorectal cancer (Zhang et al., 2007) and retrotranspositions have also been correlated to APC gene (Miki et al., 1992). Another aspect unrelated to it is Tet1 gene, which has been associated with the conversion of methylcytosine to hydroxymethyl cytosine (Tahiliani et al., 2009). DNA methylation might also have a role in the prevention of normal differentiation in pediatric cancers (Diede et al., 2009). As the difference between a nucleobase and its methylated form is its structure and its molecular weight, this research article is focussed on using the molar mass of nucleobases to find out if there is any uniqueness as for the position of occurrence of a nucleotide in a given model. SNPs occurrence position was used as a model in this research for addressing the cytosine trios (cytosine, 5methyl cytosine, hydroxy methyl cytosine) based on molar mass of the nucleobase. As the conditions for occurrence of SNP, at a given position in a sequence, were found to uniformly conform with all 140,000 SNPs analysed, including all clinically associated SNPs from NCBI SNP database, it intrigued conformity to be cross checked with SNPs near experimentally proven methylation sites.
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ABSTRACT: Small cell lung cancer (SCLC), a special type of lung cancer, is reputed to carry a poor prognosis. The morbidity of SCLC is increasing in China and other countries. A variety of DNA alterations associated with non-small cell lung cancer (NSCLC) have been described. However, genetic and epigenetic changes of SCLC are not well established. Few studies have demonstrated that epigenetic silencing of key tumor suppressor genes (TSGs) is pivotal to initiation and development of SCLC. Recently, promoter methylation of many TSGs have been identified in SCLC. These novel TSGs are potential tumor biomarkers for early diagnosis and prognostic prediction. Moreover, epigenetic promoter methylation of TSGs could be a target of intervention with a wide prospect of clinical application. This review summarizes recent studies on promoter methylation of TSGs in SCLC and aims to provide better understanding of the promoter methylation in tumorigenesis and progression of SCLC.08/2013; 5(4):532-7. DOI:10.3978/j.issn.2072-1439.2013.08.21