丁酸钠通过信号转导和转录激活因子1抑制肝癌细胞吲哚胺2，3-双加氧酶的表达

Sodium butyrate inhibited the expression of indoleamine 2, 3-dioxygenase by inhibiting phosphoryl. ation of signal transducers and activators of transcription 1 in HepG2 Cells

目的观察丁酸钠（NaB）对干扰素-1（IFN-1）诱导的人肝癌细胞HepG2内吲哚胺2，3-双加氧酶（IDO）表达的影响。方法利用低浓度（10、20、30、40mmol／L）的NaB作用于人肝癌细胞HepG224h，通过噻唑蓝（MTT）比色法检测细胞的增殖；利用蛋白印迹法及细胞免疫化学法检测NaB对HepG2细胞内IDO表达的影响；蛋白印迹法检测NaB对IDO基因表达的关键性干扰素应答因子1（IRF．1）及信号转导和转录激活因子1（STAT1）的影响。结果低浓度NaB对人肝癌细胞HepG2的增殖具有1％-20％的抑制作用；3mmol／L的NaB能完全抑制IFN-1诱导的IDO的表达；这种抑制作用通过抑制STAT-1701位的酪氨酸磷酸化实现。结论NaB通过抑制STAT1的磷酸化而抑制肝癌细胞HepG2中IDO的表达。

Objective To investigate the effect of sodium butyrate （NAB） on the expression of in- doleamine 2, 3-dioxygenase （IDO） induced by interferon （IFN）-γ in HepG2 cells. Methods HepG2 cells were treated with low concentration of NaB for 24 h, such as 10, 20, 30 and 40 mmol/L, and the proliferation of the cells was detected by methyl thiazolyl tetrazolium （MTlP） assay. The effects of NaB on IDO expression induced by IFN-~/ in HepG2 cells were demonstrated by Western blotting and immunocyto- chemistry. The transcription of interferon responsive factor-1 （ IRF-1 ） and signal transducers and activators of transcription 1 （ STAT1 ）, which were key transcription factor regulating IDO expression, were analyzed by Western blotting. Results Low concentration of NaB inhibited the proliferation of HepG2 cells, varying from 1% to 20%. And the expression of IDO in HepG2 cells was completely inhibited by 3 mmol/L NaB through inhibition of the phosphorylation of STAT1 （ tyrosine at 701 site）. Conclusion NaB could inhibit the expression of IDO in HepG2 cells through inhibiting STAT1 phosphorylation.