摘要
目的探讨莱菔子素(SFN)对结肠癌Caco-2细胞株葡萄糖醛酸转移酶1A(UGT1A)表达的诱导作用及其机制。方法采用RT-PCR及Western印迹检测SFN诱导Caco-2细胞株UGT1A及其同功型的表达,高效液相色谱法测定UGT1A的催化活性;用共聚焦激光显微镜观察核转录因子Nrf2的转位。结果(1)10~35μmol/LSFN处理组UGT1AmRNA相对系数与对照组比较差异有统计学意义(P<0·05)。UGT1AmRNA表达量与SFN的剂量呈显著正相关(r=0·79,P<0·01)。25μmol/LSFN处理组的诱导作用随着时间延长而增强,呈时间依赖性。25μmol/LSFN处理组与对照组之间UGT1A1(P=0·006)、UGT1A8(P=0·017)、UGT1A10(P=0·008)表达的差异有统计学意义。(2)10~30μmol/LSFN作用于结肠腺癌Caco-2细胞株24h,随着浓度的增加,UGT1A蛋白带的灰度值比值增加。与对照组相比,差异均有统计学意义。(3)在SFN处理组N-OH-PhIP-N2葡萄糖醛酸甙的峰值明显增高。(4)共聚焦激光显微镜观察在对照组细胞质中看到Nrf2红色荧光标记,而在25μmol/LSFN处理24h组的细胞可在胞核内看到强烈的红色荧光,表示这种信号转导因子的细胞内转位。结论(1)小剂量的SFN能诱导UGT1A及其同工型UGT1A1、1A8、1A10mRNA表达,UGT1A蛋白表达增加,对杂环胺的葡萄糖醛酸结合能力增强。(2)SFN有可能通过核转录因子Nrf2激活UGT1A基因的转录表达。
Objective To study the induction of expression of uridine 5′-diphosphate (UDP)-glucuronosyltransferase (UGT)1A in colon cancer cells by sulforaphane (SFN) and its possible mechanism. Methods Human colon cancer cells of the line Caco-2 were cultured and added with SFN of different terminal concentrations, all below the concentration of IC 50. RT-PCR was used to examine the expression of UGT1A mRNA induced by SFN. Western blotting was used to detect the expression of UGT1A protein. The glucuronidation rate of N-hydroxy-PhIP was measured by high performance liquid chromatography (HPLC). The nuclear localization of transcription factor Nrf2 was observed by confocal laser microscopy. Results (1)Expression of UGT1A mRNA was observed in the Cac0-2 cells induced by SFN of the concentrations of 10 μmol/L^35 μmol/L in a dose-independent manner (P<0.05). Sulforaphane of the concentration of 25 μmol/L induced the UGT1A mRNA expression time-dependently. The levels of UGT1A1, UGT1A8, and UGT1A10 mRNA expression were significantly increased in the cells treated with 25 μmol/L sulforaphane compared to that in the controls (P=0.006, P=0.017, and P=0.008 respectively). (2)The UGT1A protein band intensity increased significantly in the Coco-2 cells treated with sulforaphane of the concentrations 10 μmol/L ~30 μmol/L for 24 h in comparison with the control cells.(3)When the microsomes from the untreated Caco-2 cells were incubated with N-hydroxy-PhIP there was a minor HPLC peak at the expected retention time for N-hydroxy-PhIP-N2-glucuronide.This peak was dramatically increased in the sulforaphane-treated cells, suggesting higher activities of glucuronidation of N- hydroxy -PhIP. (4) Cytoplasmic labeling of NF-E2-related factor 2 (Nrf2), a transcription factor, with no nuclear staining was observed in the non-stimulated cells, whereas an intense nuclear labeling was observed in the sulforaphane-treated cells, indicating the induction of nuclear translocation of Nrf2 by sulforaphane. Conclusion (1) Low dose sulforaphane in
出处
《中华医学杂志》
CAS
CSCD
北大核心
2005年第12期819-824,共6页
National Medical Journal of China
基金
国家自然科学资助项目(30370634/C03030204)
