2,3,7,8-TCDD的短期暴露对HepG2肝癌细胞内小分子代谢产物的影响

为了研究二恶英对细胞的代谢毒性,探究其肝毒性的作用机制,以二恶英中毒性最强的2,3,7,8-四氯代二苯并-对-二恶英(TCDD)为代表污染物,以HepG2肝癌细胞为受试对象,采用四甲基偶氮唑蓝(MTT)法和高效液相色谱/串联质谱法考察了TC-DD的24h暴露对HepG2细胞的增殖活性以及细胞的葡萄糖、氨基酸、尿素和甘油等小分子代谢物的影响。结果显示,短暂的TCDD暴露对HepG2细胞的增殖活性无显著影响。24h的TCDD暴露对细胞的葡萄糖消耗量无显著影响,但当TCDD浓度增至1nmol·L-1时,葡萄糖的消耗量表现出一定的降低趋势。0.01nmol·L-1TCDD就会使细胞脯氨酸和谷氨酸的合成能力下降,且谷氨酸的变化表现出明显的剂量-效应关系;TCDD可刺激细胞对缬氨酸、苏氨酸、酪氨酸、甲硫氨酸以及亮氨酸与异亮氨酸的吸收,并具有明显的浓度依赖性。随着TCDD浓度的增加,甘油和尿素产生量的降低趋势逐渐明显,1nmol·L-1TCDD处理24h后,甘油和尿素的产生量仅为对照组的1%和18%。研究表明,TCDD在短时间内使HepG2细胞内的一系列小分子代谢产物发生了不同程度的改变,且呈现出一定的剂量-效应关系。可见,TCDD可通过干扰HepG2肝癌细胞的代谢过程产生毒性。

Effects of Short-Term Exposure to 2,3,7,8-TCDD on Low-Molecular Metabolites in HepG2 Cells

To investigate the mechanisms underlying metabolic toxicity and hepatotoxicity of dioxins, HepG2 cells were selected to be exposed to the most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 24 h, and the proliferative activity of HepG2 cells was determined by MTT assay, while low-molecular metabolites (amino acids, glucose, urea and glycerol) were qualitatively and quantitatively analyzed by HPLC-MS/MS. Results showed that short-term TCDD exposure had little effect on the proliferative activity of HepG2 cells. Glucose consumption did not change significantly after 24 h-exposure to TCDD, but only when the concentration of TCDD increased to 1 nmol·L^-1, glucose consumption showed a slight decrease. 0.01 nmol·L^-1 TCDD inhibited the synthesis of proline and glutamate in HepG2 cells, and the synthesis of glutamate decreased in an obvious dose-response manner. The absorbability of several amino acids (valine, tryptophan, tyrosine, methionine, leucine and isoleucine) was stimulated by TCDD in a dose-response manner. The productions of urea and glycerol tended to decrease with increasing TCDD concentration. After 24 h-exposure to 1 nmol·L^-1 TCDD, the productions of urea and glycerol decreased to 1% and 18% of that of the control group. These results demonstrated that short-term exposure to TCDD could affect low-molecular metabolites in HepG2 cells to different degrees. TCDD exerted toxicity to HepG2 cells by disturbing its metabolism.