Mitophagy is a degradative pathway that mediates the degradation of the entire mitochondria, and defects in this process are implicated in many diseases including cancer. In mammals, mitophagy is mediated by BNIP3L (also known as NIX) that is a dual regulator of mitochondrial turnover and programmed cell death pathways. Acute myeloid leukemia (AML) cells with deficiency of BNIP3L are more sensitive to mitochondria-targeting drugs. But small molecular inhibitors for BNIP3L are currently not available. Some immunomodulatory drugs (IMiDs) have been proved by FDA for hematologic malignancies, however, the underlining molecular mechanisms are still elusive, which hindered the applications of BNIP3L inhibition for AML treatment. In this study we carried out MS-based quantitative proteomics analysis to identify the potential neosubstrates of a novel thalidomide derivative CC-885 in A549 cells. In total, we quantified 5029 proteins with 36 downregulated in CRBN^+/+ cell after CC-885 administration. Bioinformatic analysis showed that macromitophagy pathway was enriched in the negative pathway after CC-885 treatment. We further found that CC-885 caused both dose- and time-dependent degradation of BNIP3L in CRBN^+/+, but not CRBN^−/− cell. Thus, our data uncover a novel role of CC-885 in the regulation of mitophagy by targeting BNIP3L for CRL4CRBN E3 ligase-dependent ubiquitination and degradation, suggesting that CC-885 could be used as a selective BNIP3L degradator for the further investigation. Furthermore, we demonstrated that CC-885 could enhance AML cell sensitivity to the mitochondria-targeting drug rotenone, suggesting that combining CC-885 and mitochondria-targeting drugs may be a therapeutic strategy for AML patients.

线粒体是介导整个线粒体降解的降解途径，该过程中的缺陷与包括癌症在内的许多疾病有关。在哺乳动物中，线粒体由BNIP3L（也称为NIX）介导，BNIP3L是线粒体更新和程序性细胞死亡途径的双重调节剂。缺乏BNIP3L的急性髓样白血病（AML）细胞对靶向线粒体的药物更为敏感。但是目前尚无BNIP3L的小分子抑制剂。FDA已证明某些免疫调节药物（IMiDs）可用于血液系统恶性肿瘤，但其分子机制尚不清楚，这阻碍了BNIP3L抑制在AML治疗中的应用。在这项研究中，我们进行了基于质谱的定量蛋白质组学分析，以鉴定A549细胞中新型沙利度胺衍生物CC-885的潜在新底物。总共，我们量化了5029种蛋白质，其中36种在CRBN中下调CC-885给药后^{+ / +}细胞。生物信息学分析表明，CC-885处理后，巨噬细胞通路富集于阴性通路。我们进一步发现CC-885在CRBN ^{+ / +}中引起BNIP3L的剂量依赖性和时间依赖性降解，但不会引起CRBN ^-/-细胞降解。因此，我们的数据通过靶向BNIP3L靶向CRL4CRBN E3连接酶依赖性泛素化和降解，揭示了CC-885在线粒体调控中的新作用，这表明CC-885可作为选择性BNIP3L降解物用于进一步研究。此外，我们证明CC-885可以增强AML细胞对线粒体靶向药物鱼藤酮的敏感性，这表明将CC-885与线粒体靶向药物联合使用可能是AML患者的治疗策略。