Fabrizio Federico Pio, Costantini Manuela, Copetti Massimiliano, la Torre Annamaria, Sparaneo Angelo, Fontana Andrea, Poeta Luana, Gallucci Michele, Sentinelli Steno, Graziano Paolo, Parente Paola, Pompeo Vincenzo, De Salvo Laura, Simone Giuseppe, Papalia Rocco, Picardo Francesco, Balsamo Teresa, Flammia Gerardo Paolo, Trombetta Domenico, Pantalone Angela, Kok Klaas, Paranita Ferronika, Muscarella Lucia Anna, Fazio Vito Michele
Laboratory of Oncology, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy.
Genetic and Clinic Pathology Unit, University Campus Bio-Medico of Rome, Rome, Italy.
Oncotarget. 2017 Feb 14;8(7):11187-11198. doi: 10.18632/oncotarget.14492.
The Keap1/Nrf2 pathway is a master regulator of the cellular redox state through the induction of several antioxidant defence genes implicated in chemotherapeutic drugs resistance of tumor cells. An increasing body of evidence supports a key role for Keap1/Nrf2 pathway in kidney diseases and renal cell carcinoma (RCC), but data concerning the molecular basis and the clinical effect of its deregulation remain incomplete.Here we present a molecular profiling of the KEAP1 and NFE2L2 genes in five different Renal Cell Carcinoma histotypes by analysing 89 tumor/normal paired tissues (clear cell Renal Carcinoma, ccRCCs; Oncocytomas; Papillary Renal Cell Carcinoma Type 1, PRCC1; Papillary Renal Cell Carcinoma Type 2, PRCC2; and Chromophobe Cell Carcinoma).A tumor-specific DNA methylation of the KEAP1 gene promoter region was found as a specific feature of the ccRCC subtype (18/37, 48.6%) and a direct correlation with mRNA levels was confirmed by in vitro 5-azacytidine treatment. Analysis of an independent data set of 481 ccRCC and 265 PRCC tumors corroborates our results and multivariate analysis reveals a significant correlation among ccRCCs epigenetic KEAP1 silencing and staging, grading and overall survival.Our molecular results show for the the first time the epigenetic silencing of KEAP1 promoter as the leading mechanism for modulation of KEAP1 expression in ccRCCs and corroborate the driver role of Keap1/Nrf2 axis deregulation with potential new function as independent epigenetic prognostic marker in renal cell carcinoma.
Keap1/Nrf2通路是细胞氧化还原状态的主要调节因子，可诱导多种与肿瘤细胞化疗耐药相关的抗氧化防御基因。越来越多的证据支持Keap1/Nrf2通路在肾脏疾病和肾细胞癌（RCC）中起关键作用，但关于其失调的分子基础和临床效应的数据仍不完整。在此，我们通过分析89对肿瘤/正常配对组织（透明细胞肾细胞癌，ccRCC；嗜酸性细胞瘤；1型乳头状肾细胞癌，PRCC1；2型乳头状肾细胞癌，PRCC2；以及嫌色细胞癌），对五种不同肾细胞癌组织学类型中的KEAP1和NFE2L2基因进行了分子分析。发现KEAP1基因启动子区域的肿瘤特异性DNA甲基化是ccRCC亚型的一个特征（18/37，48.6%），体外5-氮杂胞苷处理证实了其与mRNA水平的直接相关性。对481例ccRCC和265例PRCC肿瘤的独立数据集进行分析证实了我们的结果，多变量分析显示ccRCC的表观遗传KEAP1沉默与分期、分级和总生存期之间存在显著相关性。我们的分子结果首次表明KEAP1启动子的表观遗传沉默是ccRCC中KEAP1表达调控的主要机制，并证实了Keap1/Nrf2轴失调作为肾细胞癌独立表观遗传预后标志物的潜在新功能的驱动作用。
