Effect of curcumin on acetylation of histone H3 in human lymphoma cell line Raji

Abstract

BACKGROUND & OBJECTIVE: Epigenetic change is an important mechanism of oncogenesis. The inhibitors of methyltransferases and deacetylases, with epigenetic modificative effects, could inhibit proliferation and induce apoptosis of tumor cells. This study was to investigate the effects of curcumin on the acetylation of histone H3 and the expression of p21(WAF1/CIP1) gene in human lymphoma cell line Raji. METHODS: Raji cells were treated with 25 micromol/L curcumin. The levels of acetylated histone H3 and p21WAF1/CIP1 were detected by Western blot, the expression of p21(WAF1/CIP1) gene was detected by reverse transcription-polymerase chain reaction (RT-PCR), and the level of acetylated histone H3 at the site of p21(WAF1/CIP1) promoter gene was examined by chromatin immunoprecipitation assay. Cell cycle distribution was studied by flow cytometry. RESULTS: Curcumin induced hyperacetylation of histone H3 at the site of p21(WAF1/CIP1) promoter by 1.9 folds, and enhanced the levels of p21(WAF1/CIP1) mRNA by 4.2 folds and protein by 5.1 folds 24 h after treatment. Raji cells were arrested at G(2)/M phase when treated with curcumin for 24 h, and at G(0)/G(1) phase when treated for 36 h. CONCLUSION: Curcumin, with epigenetic modificative effects, could enhance the acetylayion of histone H3 at the site of p21(WAF1/CIP1) promoter gene, improve transcription of p21(WAF1/CIP1) gene, and arrest cell cycle progression of Raji cells.

背景與目的:表觀遺傳改變是腫瘤發生的一個重要原因,具有表觀遺傳修飾作用的甲基化轉移酶抑制劑和去乙酰化酶抑制劑可以抑制腫瘤增殖誘導凋亡。本研究探討姜黃素對Raji細胞組蛋白H3的乙酰化作用和細胞周期素依賴性激酶抑制劑p21WAF1/CIP1基因表達的影響。方法:用25μmol/L姜黃素作用Raji細胞不同時間,Westernblot分析乙酰化組蛋白H3和p21WAF1/CIP1變化;RT-PCR檢測p21WAF1/CIP1基因表達;染色質免疫沉淀分析p21WAF1/CIP1的啟動子基因位點組蛋白H3乙酰化水平;流式細胞術檢測細胞周期變化。結果:姜黃素提高p21WAF1/CIP1的啟動子基因位點組蛋白H3乙酰化水平1.9倍;使p21WAF1/CIP1mRNA合成增加和蛋白表達上調,在24h時分別增加了4.2倍和5.1倍;24h阻滯細胞在G2/M期,36h阻滯在G0/G1期。結論:姜黃素通過表觀遺傳修飾作用,調節p21WAF1/CIP1啟動子基因位點組蛋白H3乙酰化水平,促進p21WAF1/CIP1基因轉錄,阻滯Raji細胞周期進程。