Involvement of heat-shock protein 70 and p53 proteins in attenuation of UVC-induced apoptosis by thermal stress in hepatocellular carcinoma cells
Involvement of heat-shock protein 70 and p53 proteins in attenuation of UVC-induced apoptosis by thermal stress in hepatocellular carcinoma cells
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DOI：
10.1111/j.1751-1097.1999.tb01952.x
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发表时间：
1999-07-01
影响因子：
3.3
通讯作者：
Lin, JK
中科院分区：
文献类型：
--
作者：
Chen, YC;Lin-Shiau, SY;Lin, JK
细胞凋亡的诱导是外部刺激和细胞基因表达的功能。许多细胞通过诱导细胞凋亡来响应DNA损伤，这取决于功能性p53蛋白，并通过p53水平的升高来发出信号。在这项研究中，我们发现，先前暴露于轻度压力，（42 ℃）可以保护HepG 2（p53（+/+））细胞免受随后的由DNA片段化和亚G1峰比率确定的UV C诱导的凋亡，而对Hep 3B（p53（-/-））细胞则无热增强保护作用。热应激诱导HepG 2和Hep 3B细胞HSP 70蛋白和mRNA表达的模式相似，但热应激对紫外线诱导的HepG 2和Hep 3B细胞凋亡的影响存在明显差异。然而，这种抑制作用在转染的Hep 3B细胞中没有发生。用p53反义寡核苷酸处理HepG 2细胞，可有效阻断热应激对WC诱导的细胞凋亡的抑制作用，并通过将wtp 53表达质粒转染Hep 3B细胞，使细胞内野生型p53蛋白的表达增加，从而增强热应激对WC照射的抵抗力。结果表明p53参与了热应激对UVC辐射的抗凋亡作用。最后，在WC处理的HepG 2细胞中检测到p53蛋白的增加，并且在热应激处理后可以与HSP 70共免疫沉淀。延长p53结合活性和增强表达的p53控制的基因，如G1期阻滞和DNA损伤45和野生型p53激活因子1/Cdk相互作用蛋白1的热应力也观察到在紫外线照射的HepG 2细胞。基于这些结果，我们提出热应激的抗凋亡作用是通过增加HSP 70和调节细胞内p53功能介导的。
Induction of apoptosis is a function of external stimuli and cellular gene expression, Many cells respond to DNA damage by the induction of apoptosis, which depends on a functional p53 protein and is signaled by elevation of p53 levels, In this study, we found that a prior exposure to mild stress (42 degrees C) can protect HepG2 (p53(+/+)) cells from a subsequent UVC-induced apoptosis determined by DNA fragmentation and ratio of sub-G1 peak, but no heat-enhanced protection was found in Hep3B (p53(-/-)) cells. Although a similar inductive pattern of HSP70 protein and mRNA was detected in the two cell lines under thermal stress, the effect of thermal stress on UVC-induced apoptosis in HepG2 and Hep3B cells was obviously different, Overexpression of HSP70 by transient transfection of HSP70 expression vector in HepG2 cells significantly inhibited UVC-induced cell death; however, this inhibitory effect did not occur in transfected-Hep3B cells. Treatment of HepG2 cells with p53-specific anti-sense oligonucleotide could effectively block the antiapoptotic effect of thermal stress on WC-induced apoptosis and increase of intracellular wild-type p53 protein by transfecting wtp53 expression plasmid into Hep3B cells yielded more resistance to WC irradiation after prior thermal stress exposure. The results reveal an involvement of p53 in the antiapoptotic effect of thermal stress on UVC irradiation. Finally, a p53 protein increase was detected in WC-treated HepG2 cells and could be coimmunoprecipitated with HSP70 after a thermal stress treatment. Prolonged p53 binding activity and enhanced expression of p53-controlled genes such as G1 arrest and DNA damage 45 and wild-type p53 activation factor 1/Cdk-interacting protein 1 by thermal stress are also observed in UVC-irradiated HepG2 cells. Based on these results, we propose that the antiapoptotic effect of thermal stress is mediated by increasing HSP70 and modulating intracellular p53 function.