Purvalanol induces endoplasmic reticulum stress-mediated apoptosis and autophagy in a time-dependent manner in HCT116 colon cancer cells
Purvalanol induces endoplasmic reticulum stress-mediated apoptosis and autophagy in a time-dependent manner in HCT116 colon cancer cells
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DOI：
10.3892/or.2015.3918
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发表时间：
2015-06-01
期刊：
影响因子：
4.2
通讯作者：
Palavan-Unsal, Narcin
中科院分区：
文献类型：
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作者：
Coker-Gurkan, Ajda;Arisan, Elif Damla;Palavan-Unsal, Narcin
Purvalanol是一种新型的细胞周期蛋白依赖性激酶抑制剂，被认为是一种强凋亡诱导剂，可导致各种癌细胞如前列腺癌、乳腺癌和结肠癌细胞系的细胞周期停滞。各种生理和病理条件如葡萄糖饥饿、蛋白质糖基化抑制和氧化应激可导致未折叠蛋白在内质网（ER）中积累，从而导致未折叠蛋白反应（UPR）和自噬。由于缺乏蛋白体对未折叠蛋白聚集体的作用，内质网应激可能诱导自噬机制。自噬是一个进化上保守的过程，其特征是大量降解胞浆内容物。在本研究中，我们的目的是确定时间依赖性，ER介导的凋亡和自噬诱导purvalanol在HCT 116结肠癌细胞。十五微摩尔的purvalanol诱导细胞活力减少20和35%，在24和48小时内，分别。将HCT 116结肠癌细胞暴露于Purvalanol，Purvalanol通过在HCT 116结肠癌细胞中的早期时间点上调PERK、IRE 1 α基因表达、eIF-2 α磷酸化和ATF-6切割来激活ER应激。此外，我们确定，在purvalanol介导的内质网应激，自噬机制也被激活之前，凋亡细胞死亡的终结。Beclin-1和Atg-5的表达水平上调，LC 3裂解后6小时purvalanol处理。Purvalanol诱导线粒体膜电位的损失，caspase-7和caspase-3激活和PARP裂解后48小时的处理。因此，我们得出结论，Purvalanol在HCT 116细胞中的抗癌作用是由于ER应激介导的细胞凋亡;然而，Purvalanol触发自噬，其在早期时间点起细胞存活机制的作用。
Purvalanol, a novel cyclin-dependent kinase inhibitor, is referred to as a strong apoptotic inducer which causes cell cycle arrest in various cancer cells such as prostate, breast and colon cancer cell lines. Various physiological and pathological conditions such as glucose starvation, inhibition of protein glycosylation and oxidative stress may cause an accumulation of unfolded proteins in the endoplasmic reticulum (ER), leading to the unfolded protein response (UPR) and autophagy. Lacking proteosomal function on aggregates of unfolded proteins, ER stress may induce autophagic machinery. Autophagy, an evolutionarily conserved process, is characterized by massive degradation of cytosolic contents. In the present study, our aim was to determine the time-dependent, ER-mediated apoptotic and autophagy induction of purvalanol in HCT 116 colon cancer cells. Fifteen micromoles of purvalanol induced a reduction in cell viability by 20 and 35% within 24 and 48 h, respectively. HCT 116 colon cancer cells were exposed to purvalanol, which activated ER stress via upregulation of PERK, IREl alpha gene expression, eIF-2 alpha phosphorylation and ATF-6 cleavage at early time-points in the HCT 116 colon cancer cells. Moreover, we determined that during purvalanol-mediated ER stress, autophagic machinery was also activated prior to apoptotic cell death finalization. Beclin-1 and Atg-5 expression levels were upregulated and LC3 was cleaved after a 6 h purvalanol treatment. Purvalanol induced mitochondrial membrane potential loss, caspase-7 and caspase-3 activation and PARP cleavage following a 48 h treatment. Thus, we conclude that the anticancer effect of purvalanol in HCT 116 cells was due to ER stress-mediated apoptosis; however, purvalanol triggered autophagy, which functions as a cell survival mechanism at early time-points.