In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 72, No. 8_Supplement ( 2012-04-15), p. 4032-4032
Abstract:
Human endonuclease VIII-like1 (NEIL1) encodes a DNA glycosylase which is suggested to be involved in the repair of oxidative damage in association with DNA replication and transcription. We have recently demonstrated that hypermethylation of the NEIL1 gene promoter occurs in more than two third of head and neck squamous cell carcinoma (HNSCC) patients, and that this promoter hypermethylation correlated with a decreased expression both on the mRNA and protein levels. Further experiments were performed to investigate the relevance and functional consequence of these observations. Demethylation experiments using 5-aza-2′-deoxycytidine and DNMT1 knockdown demonstrated an up to 15-fold re-expression of NEIL1 mRNA in cultured HNSCC cells which initially carried hypermethylated promoter regions. The relevance of promoter methylation for NEIL1 expression was further studied by a luciferase promoter assay using CpG-free pCpGL vector constructs in 293T cells. A promoter construct covering the 5′ region of NEIL1 was treated with CpG methyltransferase (M.SssI) or remained untreated. Luciferase expression of the methylated NEIL1 promoter construct was significantly reduced compared to the unmethylated construct (p & lt;0.01, T-Test). Furthermore, NEIL1/2 glycosylase activity was measured in vitro using a bubble structure substrate containing 5-OHU and by quantifying the cleavage products. Nuclear extracts of HNSCC tissue samples which carried NEIL1 promoter hypermethylation showed a more than 2-fold decrease in NEIL1/2 activity when compared to extracts prepared from normal tissue samples without promoter hypermethylation. Taken together, the presented results strengthen the hypothesis that promoter hypermethylation can reduce NEIL1 gene expression and can lead to a significant loss of NEIL1/2 glycosylase activity in HNSCC tissue. NEIL1 hypermethylation may alter the cellular DNA repair capacity and thus play a role in modulating the response to DNA damaging therapies of HNSCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4032. doi:1538-7445.AM2012-4032
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/1538-7445.AM2012-4032
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2012
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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