Frequent reduced expression of alpha-1B-adrenergic receptor caused by aberrant promoter methylation in gastric cancers

Recent studies have suggested that epigenetic inactivation of tumour-related genes by promoter methylation participates in the development of gastric cancer. We newly identified the frequently aberrant promoter methylation of alpha-1B-adrenergic receptor (ADRA1B) in colorectal cancer by methylation-sensitive representational difference analysis (MS-RDA) and examined the methylation status of the ADRA1B promoter in 34 paired samples of colorectal cancer and surrounding epithelial tissue, and 34 paired samples of gastric cancer and surrounding epithelial tissue. In colorectal cancers, only four of 34 (11.8%) tumours showed ADRA1B promoter methylation. In contrast, ADRA1B promoter methylation was detected in 24 of 34 (70.6%) gastric cancers and in 14 of 34 (41.2%) surrounding epithelial tissues. The frequency of ADRA1B promoter methylation was higher in gastric epithelial tissues with intestinal metaplasia (41.6%) than in those without intestinal metaplasia (25.0%). Reverse transcription–PCR detected reduced ADRA1B expression in 12 of 18 (66.7%) gastric cancers, and its promoter methylation was detected in 11 of these 12 (91.7%) gastric cancers with reduced ADRA1B expression. Thus, ADRA1B promoter is frequently methylated in gastric cancer. Our results suggest that the ADRA1B gene is an important tumour-related gene frequently involved in the development and progression of gastric cancer

Book review: The educator's guide to LGBT plus inclusion : a practical resource for K-12 teachers, administrators, and school support staff

202202 bchyVersion of RecordNot mentionPublishe

Book review: The deviant's war : the homosexual vs. the United States of America

202202 bchyVersion of RecordNot mentionPublishe

Book review: The gay revolution : the story of the struggle

A Book Review on The Gay Revolution: The Story of the Struggle Faderman, L. (New York: Simon & Schuster), 2015, 832 pages, ISBN-13: 978-1451694123202111 bchyVersion of RecordPublishe

Safe is not enough : better schools for LGBTQ students (youth development and education series) [Book review]

202111 bchyVersion of RecordPublishe

Application of novel psychoactive substances : chemsex and HIV/AIDS policies among men who have sex with men in Hong Kong

202307 bcchVersion of RecordRGCOthersDepartment of Applied Social Sciences; Hong Kong Polytechnic University; Chinese University of Hong KongPublishe

High-throughput quantification of hMLH1 promoter methylation using Pyrosequencing™ technology

Promoter hypermethylation of hMLH1 is believed to account for the majority of hMLH1 down-regulation in sporadic gastric and colorectal cancers. As a key DNA mismatch repair gene, hMLH1 silencing leads to the manifestation of microsatellite instability (MSI), which is recognized as a specific tumorigenic pathway in both cancer types. Although biallelic methylation of the hMLH1 promoter has been demonstrated in colon cancer cell lines, such information is rarely available in primary tumors, neither can it be implied without quantitative data on methylation level. Currently, few techniques offer simple, high-throughput quantitative measurement of methylation at multiple CpG sites. Pyrosequencing technology has recently emerged for quantifying allele frequency at polymorphic sites. Its application has been extended to the measurement of methylation levels, where the cytosine methylation at individual CpG sites is viewed as a C/T polymorphism after bisulphite modification and PCR amplification. We report here a Pyrosequencing protocol for the accurate measurement of hMLH1 promoter methylation level. Assessment of methylation levels at five individual CpG sites showed a good correlation with the expected percentages of methylated population generated by the mixing of DNA from a methylated and an unmethylated cell lines in variable proportions (R2=0.97). These assessed sites were previously shown by our group and others to have a strong positive correlation with gene expression level. The specific primers chosen here showed minimal PCR bias in amplification of the methylated and unmethylated alleles. Upon measurement in gastric adenocarcinoma, a clear cut-off of below 5% methylated population (mean of five positions) was found in all non-neoplastic gastric mucosa (n=20) as well as in those tumors without hMLH1 protein loss (n=31). For those tumors with protein loss (n=19, all manifested MSI), methylation levels of 20-80% were noted. In parallel, methylation status of all tumors were determined by direct bisulphite genomic sequencing, from which data was in complete concordance with those from Pyrosequencing. Interestingly, among the methylated tumors, 42% (8/19) presented with a methylation level of less than 50%. Upon histological review, this was unlikely attributed solely to normal cells contamination, and thus may suggest additional genetic events for hMLH1 inactivation in these cases. In conclusion, Pyrosequencing was validated as a simple and reliable method for the quantification of methylation. Its application in hMLH1 methylation study, together with mutation analysis, offer a comprehensive assessment of the underlying mechanisms for hMLH1 silencing. This information will be especially useful in genetic counseling and risk prediction in patients with cancers involving hMLH1 inactivation, such as the Hereditary Non-Polyposis Colorectal Cancer

Identification of a novel gene NCRMS on chromosome 12q21 with differential expression between rhabdomyosarcoma subtypes

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Successful aging : a neuroscientist explores the power and potential of our lives [Book review]

202111 bchyVersion of RecordPublishe

Impacts of COVID-19 pandemic on psychological well-being of older chronic kidney disease patients

202110 bcvcVersion of RecordPublishe