Treatment with Panobinostat Induces Glucose-Regulated Protein 78 Acetylation and Endoplasmic Reticulum Stress in Breast Cancer Cells
Treatment with Panobinostat Induces Glucose-Regulated Protein 78 Acetylation and Endoplasmic Reticulum Stress in Breast Cancer Cells
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DOI：
10.1158/1535-7163.mct-09-0988
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发表时间：
2010-04-01
影响因子：
5.7
通讯作者：
Bhalla, Kapil N.
中科院分区：
文献类型：
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作者：
Rao, Rekha;Nalluri, Srilatha;Bhalla, Kapil N.
内质网（ER）中错误折叠多肽水平的增加触发葡萄糖调节蛋白78（GRP 78）从三种跨膜ER应激介质中解离，即，蛋白激酶RNA样ER激酶（PERK）、激活转录因子-6（ATF 6）和肌醇需要酶1 α，其导致适应性未折叠蛋白反应（UPR）。在本研究中，我们确定组蛋白脱乙酰酶-6（HDAC 6）结合并脱乙酰化GRP 78。在用泛组蛋白脱乙酰酶抑制剂帕比司他（panobinostat）（Novartis Pharmaceuticals）处理或通过短发夹RNA敲低HDAC 6后，GRP 78在11个赖氨酸残基中被乙酰化，这使GRP 78与PERK解离。这与人类乳腺癌细胞中致命UPR的激活有关。免疫共沉淀研究表明，HDAC 6与GRP 78的结合需要HDAC 6的第二个催化和COOH末端BUZ结构域。帕比司他治疗增加了磷酸化真核翻译起始因子（p-eIF 2 α）、ATF 4和CAAT/增强子结合蛋白同源蛋白（CHOP）的水平。帕比司他处理还增加了促凋亡BIK、BIM、BAX和巴克水平，以及增加了半胱天冬酶-7的活性。GRP 78的敲低使MCF-7细胞对硼替佐米和帕比司他诱导的UPR和细胞死亡敏感。这些发现表明，GRP 78与PERK的强制乙酰化和结合减少与帕比司他诱导的UPR和乳腺癌细胞的细胞死亡机制相关。Mol Cancer Ther; 9（4）; 942-52. (C)2010年AACR。
Increased levels of misfolded polypeptides in the endoplasmic reticulum (ER) triggers the dissociation of glucose-regulated protein 78 (GRP78) from the three transmembrane ER-stress mediators, i.e., protein kinase RNA-like ER kinase (PERK), activating transcription factor-6 (ATF6), and inositol-requiring enzyme 1 alpha, which results in the adaptive unfolded protein response (UPR). In the present studies, we determined that histone deacetylase-6 (HDAC6) binds and deacetylates GRP78. Following treatment with the pan-histone deacetylase inhibitor panobinostat (Novartis Pharmaceuticals), or knockdown of HDAC6 by short hairpin RNA, GRP78 is acetylated in 11 lysine residues, which dissociates GRP78 from PERK. This is associated with the activation of a lethal UPR in human breast cancer cells. Coimmunoprecipitation studies showed that binding of HDAC6 to GRP78 requires the second catalytic and COOH-terminal BUZ domains of HDAC6. Treatment with panobinostat increased the levels of phosphorylated-eukaryotic translation initiation factor (p-eIF2 alpha), ATF4, and CAAT/enhancer binding protein homologous protein (CHOP). Panobinostat treatment also increased the proapoptotic BIK, BIM, BAX, and BAK levels, as well as increased the activity of caspase-7. Knockdown of GRP78 sensitized MCF-7 cells to bortezomib and panobinostat-induced UPR and cell death. These findings indicate that enforced acetylation and decreased binding of GRP78 to PERK is mechanistically linked to panobinostat-induced UPR and cell death of breast cancer cells. Mol Cancer Ther; 9(4); 942-52. (C) 2010 AACR.