학술논문
Regulation of KEAP1expression by promoter methylation in malignant gliomas and association with patient’s outcome
Document Type
Article
Author
Muscarella, Lucia Anna; Barbano, Raffaela; D’Angelo, Vincenzo; Copetti, Massimiliano; Coco, Michelina; Balsamo, Teresa; la Torre, Annamaria; Notarangelo, Angelo; Troiano, Michele; Parisi, Salvatore; Icolaro, Nadia; Catapano, Domenico; Valori, Vanna Maria; Pellegrini, Fabio; Merla, Giuseppe; Carella, Massimo; Fazio, Vito Michele; Parrella, Paola
Source
Epigenetics; March 2011, Vol. 6 Issue: 3 p317-325, 9p
Subject
Language
ISSN
15592294; 15592308
Abstract
In light with the view that KEAP1loss of function may impact tumour behavior and modify response to chemotherapeutical agents, we sought to determine whether KEAP1gene is epigenetically regulated in malignant gliomas. We developed a Quantitative Methylation Specific PCR (QMSP) assay to analyze 86 malignant gliomas and 20 normal brain tissues. The discriminatory power of the assay was assessed by Receiving Operating Characteristics (ROC) curve analysis. The AUC value of the curve was 0.823 (95%CI: 0.764-0.883) with an optimal cut off value of 0.133 yielding a 74% sensitivity (95%CI: 63%-82%) and an 85% specificity (95%CI: 64%-95%). Bisulfite sequencing analysis confirmed QMSP results and demonstrated a direct correlation between percentage of methylated CpGs and methylation levels (Spearman’s Rho 0.929, P=0.003). Remarkably, a strong inverse correlation was observed between methylation levels and KEAP1mRNA transcript in tumour tissue (Spearman’s Rho -0.656 P=0.0001) and in a cell line before and after treatment with 5-azacytidine (P=0.003). RECPAM multivariate statistical analysis studying the interaction between MGMTand KEAP1methylation in subjects treated with radiotherapy and temozolomide (n=70), identified three prognostic classes of glioma patients at different risk to progress. While simultaneous methylation of MGMTand KEAP1promoters was associated with the lowest risk to progress, patients showing only MGMTmethylation were the subgroup at the higher risk (HR 5.54, 95% CI 1.35-22.74). Our results further suggest that KEAP1expression is epigenetically regulated. In addition we demonstrated that KEAP1is frequently methylated in malignant gliomas and a predictor of patient’s outcome.