Department of Pediatric Oncology/Hematology (D.N., L.F.V.R., J.v.M., G.J.L.K., J.C.), Department of Rheumatology (G.J.), and Department of Hematology (J.v.M., S.Z., J.C.), VU University Medical Center, Amsterdam, The Netherlands; Scripps Institution of Oceanography and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, San Diego, California (A.J.K., B.S.M.); The Fred Wyszkowski Cancer Research Laboratory, Technion-Israel Institute of Technology, Haifa, Israel (Y.G.A.); and Research Department, Onyx Pharmaceuticals Inc., South San Francisco, California (J.L.A.).
Department of Pediatric Oncology/Hematology (D.N., L.F.V.R., J.v.M., G.J.L.K., J.C.), Department of Rheumatology (G.J.), and Department of Hematology (J.v.M., S.Z., J.C.), VU University Medical Center, Amsterdam, The Netherlands; Scripps Institution of Oceanography and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, San Diego, California (A.J.K., B.S.M.); The Fred Wyszkowski Cancer Research Laboratory, Technion-Israel Institute of Technology, Haifa, Israel (Y.G.A.); and Research Department, Onyx Pharmaceuticals Inc., South San Francisco, California (J.L.A.)
Mol Pharmacol. 2014 Jul;86(1):12-9. doi: 10.1124/mol.114.092114. Epub 2014 Apr 15.
Salinosporamide A (NPI-0052, marizomib) is a naturally occurring proteasome inhibitor derived from the marine actinobacterium Salinispora tropica, and represents a promising clinical agent in the treatment of hematologic malignancies. Recently, these actinobacteria were shown to harbor self-resistance properties to salinosporamide A by expressing redundant catalytically active mutants of the 20S proteasome β-subunit, reminiscent of PSMB5 mutations identified in cancer cells with acquired resistance to the founding proteasome inhibitor bortezomib (BTZ). Here, we assessed the growth inhibitory potential of salinosporamide A in human acute lymphocytic leukemia CCRF-CEM cells, and its 10-fold (CEM/BTZ7) and 123-fold (CEM/BTZ200) bortezomib-resistant sublines harboring PSMB5 mutations. Parental cells displayed sensitivity to salinosporamide A (IC50 = 5.1 nM), whereas their bortezomib-resistant sublines were 9- and 17-fold cross-resistant to salinosporamide A, respectively. Notably, combination experiments of salinosporamide A and bortezomib showed synergistic activity in CEM/BTZ200 cells. CEM cells gradually exposed to 20 nM salinosporamide A (CEM/S20) displayed stable 5-fold acquired resistance to salinosporamide A and were 3-fold cross-resistant to bortezomib. Consistent with the acquisition of a PSMB5 point mutation (M45V) in CEM/S20 cells, salinosporamide A displayed a markedly impaired capacity to inhibit β5-associated catalytic activity. Last, compared with parental CEM cells, CEM/S20 cells exhibited up to 2.5-fold upregulation of constitutive proteasome subunits, while retaining unaltered immunoproteasome subunit expression. In conclusion, salinosporamide A displayed potent antileukemic activity against bortezomib-resistant leukemia cells. β-Subunit point mutations as a common feature of acquired resistance to salinosporamide A and bortezomib in hematologic cells and S. tropica suggest an evolutionarily conserved mechanism of resistance to proteasome inhibitors.
沙利度胺 A（NPI-0052，马利佐米）是一种天然存在的蛋白酶体抑制剂，来源于海洋放线菌盐孢菌，是治疗血液恶性肿瘤的一种很有前途的临床药物。最近，这些放线菌被证明通过表达冗余的 20S 蛋白酶体β亚单位的催化活性突变体来抵抗沙利度胺 A，这让人想起了在对最初的蛋白酶体抑制剂硼替佐米（BTZ）获得耐药性的癌细胞中发现的 PSMB5 突变。在这里，我们评估了沙利度胺 A 对人急性淋巴细胞白血病 CCRF-CEM 细胞及其对硼替佐米的 10 倍（CEM/BTZ7）和 123 倍（CEM/BTZ200）耐药亚系的生长抑制潜力，这些亚系携带有 PSMB5 突变。亲本细胞对沙利度胺 A 敏感（IC50=5.1 nM），而它们的硼替佐米耐药亚系对沙利度胺 A 的交叉耐药性分别为 9 倍和 17 倍。值得注意的是，沙利度胺 A 和硼替佐米的组合实验在 CEM/BTZ200 细胞中显示出协同活性。逐渐暴露于 20 nM 沙利度胺 A 的 CEM 细胞（CEM/S20）对沙利度胺 A 表现出稳定的 5 倍获得性耐药性，对硼替佐米的交叉耐药性为 3 倍。与 CEM/S20 细胞中获得 PSMB5 点突变（M45V）一致，沙利度胺 A 抑制β5 相关催化活性的能力明显受损。最后，与亲本 CEM 细胞相比，CEM/S20 细胞的组成型蛋白酶体亚基表达上调高达 2.5 倍，而免疫蛋白酶体亚基表达不变。总之，沙利度胺 A 对硼替佐米耐药性白血病细胞具有强大的抗白血病活性。β-亚基点突变是血液细胞和盐孢菌获得性耐药沙利度胺 A 和硼替佐米的共同特征，表明蛋白酶体抑制剂耐药具有进化上保守的机制。
