The novel cereblon modulator CC-885 inhibits mitophagy via selective degradation of BNIP3L

Abstract

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.

Selective Degradation of GSPT1 by Cereblon Modulators Identified via a Focused Combinatorial Library

“…The majority of the 51 compounds in the library exhibited no antiproliferative activity in either MM1.S wild-type (WT) or CRBN −/− up to a concentration of 20 μM. Seven compounds (8,25,36,42,43,44, and 47) had notable to slight antiproliferative activity in both cell lines (Table 1, Supplementary Figure S1). This indicated that these compounds have CRBN-independent cytotoxicity.…”

“…Screening for CRBN-dependent antiproliferative effects led to the identification of CRBN modulators that can induce the selective degradation of GSPT1. In contrast to CC-885, which induces degradation of GSPT1, IKZF1/3, and a large number of other proteins, 12,24,25 our tool compounds are highly selective GSPT1/2 degraders with little to no activity on IKZF1/3 and no observable offtarget activity in global proteomics. This is confirmed by our selective tool compounds exhibiting antiproliferative activity that is strictly dependent on the expression of CRBN, while CC-885 retains antiproliferative activity with unspecific toxicity in a CRBN −/− cell line (Figure 4D).…”

Expression and Clinical Significance of BCL2 Interacting Protein 3 Like in Multiple Myeloma

“…33 Another example showed that AML cells with BNIP3L deficiency were reported to be more sensitive to mitochondria-targeting drugs. 34 Furthermore, BNIP3L expression was also upregulated by decitabine in myeloid cells. 28 These studies will help incorporate BNIP3L into new therapeutic strategies for MM.…”

CRL4CRBN E3 Ligase Complex as a Therapeutic Target in Multiple Myeloma

“…Furthermore, a recent analysis based on mass-spectroscopy proteomics also identified dose- and time-dependent degradation of BNIP3L in CRBN +/+ , but not CRBN −/− cells exposed to CC-885 compound. That data uncover a novel role of CC-885 in regulating degradation of mitochondria (mitophagy) by targeting BNIP3L for CRL4 CRBN E3 ligase-dependent ubiquitination [ 83 ]. In MM cell lines, CC-885 selectively induced the ubiquitination and degradation of CDK4 in a CRBN-dependent manner, suggesting that CDK4 destruction contributed to its cytotoxicity in MM pre-clinical model [ 84 ].…”