School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan.
School of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, 820-0067, Japan.
Sci Rep. 2020 Mar 4;10(1):4012. doi: 10.1038/s41598-020-61027-w.
Pomalidomide, a derivative of thalidomide, is an effective treatment for multiple myeloma. The drug exerts its effects through CRBN, a component of the E3 ubiquitin ligase complex CRL4. To search for novel factors involved in the anti-cancer activity of pomalidomide, we performed a genome-wide shRNA library screen and identified 445 genes as those affecting pomalidomide sensitivity. Genes encoding components of the ubiquitin-proteasome pathway, such as subunits of the CRL4 complex, the COP9 signalosome, and the 26S proteasome, were among the pomalidomide-affecting genes. Karyopherin beta 1 (KPNB1) was identified as a novel pomalidomide-affecting gene. KPNB1 was required for the nuclear import of CRBN and for the CRBN-directed, pomalidomide-dependent degradation of a clinically relevant substrate, the transcription factor Aiolos. By contrast, the cytoplasmic translation factor GSPT1 was degraded following treatment with the thalidomide derivative CC-885 only when CRBN was present in the cytoplasm, indicating that subcellular distribution of CRBN is critical for the efficacy of thalidomide-based medications.
泊马度胺是沙利度胺的衍生物，是多发性骨髓瘤的有效治疗药物。该药物通过 CRBN 发挥作用，CRBN 是 E3 泛素连接酶复合物 CRL4 的一个组成部分。为了寻找参与泊马度胺抗癌活性的新型因子，我们进行了全基因组 shRNA 文库筛选，确定了 445 个基因作为影响泊马度胺敏感性的基因。编码泛素-蛋白酶体途径成分的基因，如 CRL4 复合物、COP9 信号体和 26S 蛋白酶体的亚基，都属于泊马度胺作用基因。核孔蛋白β 1（KPNB1）被鉴定为泊马度胺作用的新基因。KPNB1 是 CRBN 核输入所必需的，也是 CRBN 定向的、依赖泊马度胺的、临床上相关的底物转录因子 Aiolos 降解所必需的。相比之下，只有当细胞质中存在 CRBN 时，细胞溶质翻译因子 GSPT1 才会在沙利度胺衍生物 CC-885 处理后被降解，这表明 CRBN 的亚细胞分布对基于沙利度胺的药物的疗效至关重要。
