Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-35321
Hofstetter, B; Niemierko, A; Forrer, C; Benhattar, J; Albertini, V; Pruschy, M; Bosman, F T; Catapano, C V; Ciernik, I F (2010). Impact of genomic methylation on radiation sensitivity of colorectal carcinoma. International Journal of Radiation Oncology, Biology and Physics, 76(5):1512-1519.
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PURPOSE: To investigate the influence of demethylation with 5-aza-cytidine (AZA) on radiation sensitivity and to define the intrinsic radiation sensitivity of methylation deficient colorectal carcinoma cells. METHODS AND MATERIALS: Radiation sensitizing effects of AZA were investigated in four colorectal carcinoma cell lines (HCT116, SW480, L174 T, Co115), defining influence of AZA on proliferation, clonogenic survival, and cell cycling with or without ionizing radiation. The methylation status for cancer or DNA damage response-related genes silenced by promoter methylation was determined. The effect of deletion of the potential target genes (DNMT1, DNMT3b, and double mutants) on radiation sensitivity was analyzed. RESULTS: AZA showed radiation sensitizing properties at >or=1 micromol/l, a concentration that does not interfere with the cell cycle by itself, in all four tested cell lines with a sensitivity-enhancing ratio (SER) of 1.6 to 2.1 (confidence interval [CI] 0.9-3.3). AZA successfully demethylated promoters of p16 and hMLH1, genes associated with ionizing radiation response. Prolonged exposure to low-dose AZA resulted in sustained radiosensitivity if associated with persistent genomic hypomethylation after recovery from AZA. Compared with maternal HCT116 cells, DNMT3b-defcient deficient cells were more sensitive to radiation with a SER of 2.0 (CI 0.9-2.1; p = 0.03), and DNMT3b/DNMT1-/- double-deficient cells showed a SER of 1.6 (CI 0.5-2.7; p = 0.09). CONCLUSIONS: AZA-induced genomic hypomethylation results in enhanced radiation sensitivity in colorectal carcinoma. The mediators leading to sensitization remain unknown. Defining the specific factors associated with radiation sensitization after genomic demethylation may open the way to better targeting for the purpose of radiation sensitization.
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|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||04 Faculty of Medicine > University Hospital Zurich > Clinic for Radiation Oncology|
|DDC:||610 Medicine & health|
|Deposited On:||09 Aug 2010 10:23|
|Last Modified:||14 Dec 2013 02:08|
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