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Promoter hypermethylation and downregulation of the FAS gene may be involved in colorectal carcinogenesis.

ABSTRACT: Aberrant DNA methylation has been investigated in carcinogenesis and as biomarker for the early detection of colorectal cancer (CRC). The present study aimed to define the methylation status in the regulatory elements of two proapoptotic genes, Fas cell surface death receptor (FAS) and BCL2-associated X protein (BAX). DNA methylation analysis was performed in tumor and adjacent normal tissue using HpaII/MspI restriction digestion and methylation-specific polymerase chain reaction (PCR). The results observed downregulation of the FAS and BAX genes in the CRC tissues compared with the adjacent normal samples. Furthermore, demethylation using 5-aza-2'-deoxycytidine treatment followed by reverse-transcription quantitative PCR were performed on the HT-29 cell line to measure BAX and FAS mRNA expression following demethylation. The 5-aza-2'-deoxycytidine treatment resulted in significant FAS gene upregulation in the HT-29 cell line, but no significant difference in BAX expression. Furthermore, analysis of CpG islands in the FAS gene promoter revealed that the FAS promoter was significantly hypermethylated in 53.3% of tumor tissues compared with adjacent normal samples. Taken together, the results indicate that decreased expression of the FAS gene due to hypermethylation of its promoter may lead to apoptotic resistance, and acts as an important step during colorectal carcinogenesis.

SUBMITTER: Manoochehri M

PROVIDER: S-EPMC4906593 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Promoter hypermethylation and downregulation of the FAS gene may be involved in colorectal carcinogenesis.

Manoochehri Mehdi M Borhani Nasim N Karbasi Ashraf A Koochaki Ameneh A Kazemi Bahram B

Oncology letters 20160516 1

Aberrant DNA methylation has been investigated in carcinogenesis and as biomarker for the early detection of colorectal cancer (CRC). The present study aimed to define the methylation status in the regulatory elements of two proapoptotic genes, Fas cell surface death receptor (FAS) and BCL2-associated X protein (BAX). DNA methylation analysis was performed in tumor and adjacent normal tissue using <i>Hpa</i>II/<i>Msp</i>I restriction digestion and methylation-specific polymerase chain reaction ( ...[more]

PMID: 27347139

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Project description:BACKGROUND:MicroRNAs are dysregulated in colorectal cancer and subsets correlated with advanced tumor stage and metastasis. Data are lacking on microRNA dysregulation from early to late-stage disease. OBJECTIVE:The purpose of this study was to identify a microRNA signature associated with the primary tumor and metastatic site in stage IV disease and to examine whether the signature is evident in earlier stages. DESIGN:A microRNA profile was generated and then explored in normal colon tissue (n = 5), early stage (stage I and II; n = 10), and late-stage (stage III and IV; n = 14) colorectal primary tumors via polymerase chain reaction to delineate molecular events that may promote colorectal carcinogenesis. SETTING:Genome-wide microRNA expression profiling was performed. PATIENTS:A total of 14 patient-matched stage IV primary colorectal cancer tumors and corresponding liver metastases were included. MAIN OUTCOME MEASURES:MicroRNA array technology was used to identify microRNA expression-predictive metastatic potential in the primary tumor. RESULTS:A distinct 9-member signature group of microRNAs was concurrent in stage IV primary colorectal cancer and their corresponding liver metastases, when compared with surrounding unaffected colon and liver tissue (microRNA-18b, microRNA-93, microRNA-182, microRNA-183, microRNA21, microRNA-486-5p, microRNA-500a, microRNA-552, and microRNA-941). Of the microRNA panel, only microRNA486-5p was differentially expressed in early stage colorectal cancer samples compared with normal tissue (p = 0.001) and additionally differentially expressed between late-stage colorectal cancer samples and normal tissue (p < 0.01). LIMITATIONS:Our microRNA profile was generated in a small subset of patients and will require validation in more samples. CONCLUSIONS:We identified a distinct microRNA signature in primary colon and matched metastatic disease. On additional investigation, 1 microRNA was differentially expressed in both early and late-stage cancer patient samples, and it may herald an early event in colorectal carcinogenesis. This study warrants additional investigation with a larger patient cohort to better understand the effect of microRNAs in carcinogenesis. See Video Abstract at http://links.lww.com/DCR/A723.

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Promoter hypermethylation and downregulation of the FAS gene may be involved in colorectal carcinogenesis.

Publications

Promoter hypermethylation and downregulation of the FAS gene may be involved in colorectal carcinogenesis.

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