ORIGINAL ARTICLE Characterization of the ubiquitin-proteasome system in bortezomib-adapted cells
ORIGINAL ARTICLE Characterization of the ubiquitin-proteasome system in bortezomib-adapted cells
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发表时间：
2009
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通讯作者：
M. Kraus;Jeannette Gogel;A. Beck;H. Ovaa;M. Verdoes;H. Overkleeft;H. Kalbacher;C. Driessen
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作者：
M. Kraus;Jeannette Gogel;A. Beck;H. Ovaa;M. Verdoes;H. Overkleeft;H. Kalbacher;C. Driessen
对蛋白酶体抑制剂硼替佐米的耐药性知之甚少。我们使 HL-60、ARH-77 和 AMO-1 细胞系（骨髓性白血病、浆细胞样淋巴瘤、骨髓瘤）适应超过治疗血浆水平的硼替佐米，并比较了适应细胞和亲代细胞系之间的泛素-蛋白酶体系统、替代蛋白酶和未折叠蛋白反应 (UPR) 的特征。适应细胞表现出硼替佐米敏感的b5以及b2蛋白酶体亚基的转录率、活性和多肽水平增加，并且在治疗水平的硼替佐米存在下始终保持活性b1/b5型蛋白酶体亚基水平的升高。硼替佐米适应的 HL-60 细胞表现出 11S 蛋白酶体激活剂的表达和蛋白酶体关联增加，并且不会积累多聚泛素化蛋白，不会响应硼替佐米激活 UPR 或 UPR 介导的细胞凋亡。蛋白质生物合成速率降低，伴侣基因转录下调。我们没有观察到 TPPII、组织蛋白酶或去泛素化蛋白酶的活性发生重大变化。我们的结论是，不同类型的硼替佐米适应细胞系，包括骨髓瘤，在蛋白酶体机制中表现出相似的变化模式，这导致在硼替佐米存在下残留蛋白酶体活性以及蛋白质生物合成和破坏之间的定量平衡。
Resistance towards the proteasome inhibitor bortezomib is poorly understood. We adapted the HL-60, ARH-77 and AMO-1 cell lines (myeloid leukemia, plasmocytoid lymphoma, myeloma) to bortezomib exceeding therapeutic plasma levels, and compared characteristics of the ubiquitin–proteasome system, alternative proteases and the unfolded protein response (UPR) between adapted cells and parental lines. Adapted cells showed increased transcription rates, activities and polypeptide levels of the bortezomib-sensitive b5, but also of the b2 proteasome subunit and consistently retained elevated levels of active b1/b5-type proteasome subunits in the presence of therapeutic levels of bortezomib. Bortezomib-adapted HL-60 cells showed increased expression and proteasome association of the 11S proteasome activator, and did not accumulate poly-ubiquitinated protein, activate the UPR or UPR-mediated apoptosis in response to bortezomib. The rate of protein biosynthesis was reduced, and the transcription of chaperone genes downmodulated. We did not observe major changes in the activities of TPPII, cathepsins or deubiquitinating proteases. We conclude that different types of bortezomib-adapted cell lines, including myeloma, show similar patterns of changes in the proteasomal machinery which result in residual proteasome activity in the presence of bortezomib and a quantitative balance between protein biosynthesis and destruction.