Cycloheximide protects HepG2 cells from serum withdrawal-induced apoptosis by decreasing p53 and phosphorylated p53 levels
Cycloheximide protects HepG2 cells from serum withdrawal-induced apoptosis by decreasing p53 and phosphorylated p53 levels
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DOI：
10.1124/jpet.106.110007
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发表时间：
2006-12-01
影响因子：
3.5
通讯作者：
Cederbaum, Arthur I.
中科院分区：
文献类型：
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作者：
Bai, Jingxiang;Cederbaum, Arthur I.
环己酰亚胺 (CHX) 是一种蛋白质合成抑制剂，据报道可以防止多种细胞类型中由不同细胞凋亡刺激产生的细胞死亡。然而，CHX 保护细胞免于凋亡的机制仍不清楚。在本研究中，我们研究了 p53 是否在 CHX 保护血清戒断诱导的细胞凋亡中发挥作用。从培养基中去除血清会导致 HepG2 细胞凋亡，而 CHX 可以显着保护细胞免于死亡。 p53、p21 和 Bax 蛋白水平升高，血清停药后细胞周期停滞。 CHX 消除了 p53、p21 和 Bax 的升高以及血清剥夺引起的细胞周期停滞。 p53 抑制剂 Pifithrin-alpha 可以保护 HepG2 细胞免受血清撤药诱导的细胞凋亡。表达显性失活形式的突变型 p53 的 HepG2 细胞和缺乏 p53 的 Hep3B 细胞对血清撤药诱导的细胞凋亡具有抵抗力。通过小干扰 RNA 降低 p53 可保护 HepG2 细胞免受血清停药诱导的细胞凋亡。 p53 磷酸化是由血清停药和其他化疗试剂（例如放线菌素 D、阿霉素和依托泊苷）诱导的。即使存在蛋白酶体抑制剂，CHX 也会降低磷酸化 p53 (pp53) 的水平，从而维持总 p53 水平，而不会影响 pp53 的去磷酸化。这些结果表明磷酸化 p53 的激酶可能会受到 CHX 给药的影响。总之，CHX 通过抑制 p53 的合成和 p53 的磷酸化来保护 HepG2 细胞免受血清撤药诱导的细胞凋亡。
Cycloheximide (CHX), an inhibitor of protein synthesis, has been reported to prevent cell death in a wide variety of cell types and produced by different apoptotic stimuli. However, the mechanisms by which CHX protects cells from apoptosis are still unclear. In this study, we investigated whether p53 plays a role in the protection by CHX against serum withdrawal-induced apoptosis. Deprivation of serum from the culture medium causes apoptosis in HepG2 cells, and CHX dramatically protects cells from death. p53, p21, and Bax protein levels were elevated, and cell cycle arrest was produced after serum withdrawal. CHX abolished this elevation of p53, p21, and Bax as well as the cell cycle arrest induced by serum deprivation. The p53 inhibitor pifithrin-alpha protects HepG2 cells against apoptosis induced by serum withdrawal. HepG2 cells expressing a dominant negative form of mutant p53 and Hep3B cells lacking p53 were resistant to serum withdrawal-induced apoptosis. Lowering of p53 by small interfering RNA protects HepG2 cells from serum withdrawal-induced apoptosis. p53 phosphorylation was induced by serum withdrawal and other chemotherapeutic reagents such as actinomycin D, doxorubicin, and etoposide. CHX decreases the levels of phosphorylated p53 (pp53) even in the presence of a proteasome inhibitor, which maintains the total p53 levels, whereas it does not affect the dephosphorylation of pp53. These results suggest the possibility that kinases that phosphorylate p53 might be affected by CHX administration. In summary, CHX protects HepG2 cells from serum withdrawal-induced apoptosis through inhibiting the synthesis of p53 and the phosphorylation of p53.