Jiménez-López José M, Carrasco María P, Segovia Josefa L, Marco Carmen
Faculty of Sciences, Department of Biochemistry and Molecular Biology, University of Granada, Avenida Fuentenueva s/n, Granada 18001, Spain.
Biochem Pharmacol. 2002 Apr 15;63(8):1485-90. doi: 10.1016/s0006-2952(02)00896-1.
The influence of both short- and long-term ethanol exposure on the lipid metabolism was determined in the human hepatoma cell line HepG2. Ethanol did not cause any cytotoxicity or lipid peroxidation even after 7 days of 100 mM ethanol treatment of HepG2 cells. Incubation of cells in the presence of [1-(14)C]ethanol demonstrated that these cells actively metabolize ethanol to acetyl CoA, incorporating the radioactive label into neutral lipids and phospholipids. [1,2,3-(3)H]glycerol was efficiently used in phospholipid and neutral lipid biosynthesis, showing higher radioactivity in phosphatidylcholine, phosphatidylethanolamine and triacylglycerols. Exposure of HepG2 cells to 100 mM ethanol for 24 hr did not significantly modify the incorporation of glycerol into newly synthesized phospholipids and neutral lipids, nor was lipid degradation affected by the presence of ethanol. When the alcohol treatment was prolonged for 7 days, incorporation of [1,2,3-(3)H]glycerol into triacylglycerols and diacylglycerols showed a slight increase concomitantly with decreased radioactivity in the major phospholipids, phosphatidylcholine and phosphatidylethanolamine. In addition, these changes were associated with a greater release of radiolabeled triacylglycerols into the culture medium. These results indicate that ethanol does not cause in HepG2 cells the marked lipogenic stimulation widely shown in hepatocytes, and demonstrate that HepG2 cells strongly resist the adverse effects of ethanol. Since these cells lack the isoenzymatic form of cytochrome P(450) mainly involved in the ethanol metabolism (namely cytochrome P(450)2E1) and also are devoid of alcohol dehydrogenase activity, we propose that the toxic actions of ethanol on liver must be linked to the activity of one or both of these systems.
在人肝癌细胞系HepG2中测定了短期和长期乙醇暴露对脂质代谢的影响。即使在对HepG2细胞进行100 mM乙醇处理7天后，乙醇也未引起任何细胞毒性或脂质过氧化。在[1-(14)C]乙醇存在下培养细胞表明，这些细胞可将乙醇积极代谢为乙酰辅酶A，将放射性标记掺入中性脂质和磷脂中。[1,2,3-(3)H]甘油被有效地用于磷脂和中性脂质的生物合成，在磷脂酰胆碱、磷脂酰乙醇胺和三酰甘油中显示出较高的放射性。将HepG2细胞暴露于100 mM乙醇24小时，并未显著改变甘油掺入新合成的磷脂和中性脂质中的情况，乙醇的存在也未影响脂质降解。当乙醇处理延长至7天时，[1,2,3-(3)H]甘油掺入三酰甘油和二酰甘油中的量略有增加，同时主要磷脂磷脂酰胆碱和磷脂酰乙醇胺中的放射性降低。此外，这些变化与放射性标记的三酰甘油向培养基中的释放增加有关。这些结果表明，乙醇在HepG2细胞中不会引起肝细胞中广泛显示的明显的脂肪生成刺激，并表明HepG2细胞对乙醇的不良反应具有很强的抵抗力。由于这些细胞缺乏主要参与乙醇代谢的细胞色素P(450)的同工酶形式（即细胞色素P(450)2E1），并且也缺乏乙醇脱氢酶活性，我们提出乙醇对肝脏的毒性作用必须与这两个系统中的一个或两个的活性相关联。
