Promoter Hypermethylation of the EGFR-Signaling Genes in HNSCC
Alexis Bousamra, Haihong Zhang, Steven A Schichman, Chun-Yang Fan. University Arkansas for Med Sciences, Little Rock, AR; Central Arkansas Veterans Healthcare System, Little Rock, AR
Background: Epidermal Growth Factor Receptor (EGFR) signaling pathway appears critically important in the pathogenesis of head and neck squamous cell carcinomas (HNSCC). For the above reason, there has been immense interest in exploring targeted therapies aiming at EGFR, using either EGFR tyrosine kinase inhibitors (EGFR-TKI) or anti-EGFR monoclonal antibodies (EGFR-mab) for HNSCC. Characterization of epigenetic regulation of EGFR signaling genes (EGFR, E-Cadherin, PTEN and SCOS1) may lead to more effective treatment of HNSCC using EGFR-targeted therapies. Promoter hypermethylation has long been established as one epigenetic mechanism for gene silencing of tumor suppressior genes in human cancer.
Design: Promoter sequences of 4 EGFR signaling genes (EGFR, E-cadherin, PTEN and SCOS1) were analyzed for the presence or absence of CPG island using CpG Plot software and primers were designed for methylation-specific PCR (MSP) to detect promoter hypermethylation in these 4 genes. Genomic DNA samples were extracted from 6 cultured HNSCC cell lines, modified with sodium bisophite, followed by PCR amplification and agarose gel electrophoresis.
Results: All 4 EGFR signaling genes (EGFR, E-cadherin, PTEN and SCOS1) contain a CpG island in their respective promoter sequence, ranging from 233 to 602 basepairs. Following MSP, We detected promoter hypermethylation in 6 of 6 (100%) HNSCC cell lines for the SOC1 gene and in 1 of 6 (16%) cancer cell lines for the ECAD1 gene. No promoter methylation was detected for the EGFR and PTEN genes in any of the cell lines.
Conclusions: The presence of promoter hypermethylation in two important genes (SOC1 and ECAD1) of the EGFR-signaling pathway in HNSCC cell lines supports that the expression of these genes can be silenced by promoter hypermethylation in HNSCC and that DNA Demethylating agent, such as 5-azacytidine, may be use to improve the response of HNSCC to EGFR-targeted therapies by modulating the expression levels of some key EGFR-signaling genes.
Category: Head & Neck
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 203, Wednesday Morning