Neddylation inhibition upregulates PD‐L1 expression and enhances the efficacy of immune checkpoint blockade in glioblastoma

Abstract

Pevonedistat (MLN4924), a specific NEDD8‐activating enzyme inhibitor, has been considered as a promising treatment for glioblastoma, which is currently in Phase I/II clinical trials. On the other hand, inhibition of neddylation pathway substantially upregulates the expression of T cell negative regulator programmed death‐ligand 1 (PD‐L1), which might account for the potential resistance via evasion of immune surveillance checkpoints. Whether administration of anti‐PD‐L1 enhances the efficacy of pevonedistat through a cytotoxic T cell‐dependent mechanism in glioblastoma needs to be investigated. Here, we report that depletion of neddylation pathway key enzymes markedly elevates PD‐L1 expression in glioblastoma cancer cells. Consistently, neddylation inhibitor pevonedistat significantly enhances PD‐L1 expression in both glioblastoma cancer cell lines and animal models. Mechanistically, pevonedistat increases PD‐L1 mRNA levels mainly through inhibiting Cullin1‐F‐box and WD repeat domain‐containing 7 E3 ligase activity and accumulating c‐MYC proteins, a direct transcriptional activator of PD‐L1 gene expression. In addition, inhibition of Cullin3 activity by pevonedistat also blocks PD‐L1 protein degradation. Importantly, pevonedistat attenuates T cell killing through PD‐L1 induction, and blockade of PD‐L1 restores the sensitivity of pevonedistat‐treated glioblastoma cancer cells to T cell killing. The combination of pevonedistat and anti‐PD‐L1 therapy compared to each agent alone significantly increased the therapeutic efficacy in vivo. Our study demonstrates inhibition of neddylation pathway suppresses cancer‐associated immunity and provides solid evidence to support the combination of pevonedistat and PD‐L1/programmed cell death protein 1 immune checkpoint blockade as a potential therapeutic strategy to treat glioblastoma.

PD-L1 degradation pathway and immunotherapy for cancer

“…The high expression of PD-L1 protein levels is observed in different types of cancers, which promotes cancer cell immune escape 5,7 . The expression of PD-L1 in cancer cells is regulated by multiple signaling pathways, including NFκB, MAPK, mTOR, STAT, and c-Myc 8,9 , while PD-L1 protein undergoes degradation in proteasomes or lysosomes by multiple pathways [10][11][12][13][14][15][16] , leading to increased effectiveness of cancer immunotherapy (Figs. 1 and 2 and Tables 1 and 2).…”

The pivotal roles of neddylation pathway in immunoregulation

“…43 Neddylation inactivation also upregulates PD-L1 expression on glioblastoma cell lines by stabilization of c-Myc. 54 Adaptor protein Shc is another target for neddylation, which facilitating the formation of the ZAP70-Shc-Grb2 complex and downstream Erk activation. 48 NEDD8 modification of Itch, leading to degradation of FoxO1, promotes Tfh cell differentiation.…”

“…57 Another study indicated that neddylation inhibition significantly enhances Cullin-1/c-Mycmodulated PD-L1 expression in glioblastoma cancer cell lines, resulting in T-cell exhaustion and attenuated T-cell killing. 54 Besides of solid tumors, unique effects of neddylation inhibition on lymphoid malignancies have been discussed recently. NAE inhibition treated T cells derived from patients with chronic lymphocytic leukemia exert markedly differential expression of NF-κB-regulated genes and downregulated of interleukin-2 signaling during T-cell activation.…”

“…Neddylation leads to repressed Deptor accumulation by the conjugation of Nedd8 to Cullin‐1 and sequentially promotes the mechanistic target of rapamycin kinase (mTOR) activity 43 . Neddylation inactivation also upregulates PD‐L1 expression on glioblastoma cell lines by stabilization of c‐Myc 54 . Adaptor protein Shc is another target for neddylation, which facilitating the formation of the ZAP70‐Shc‐Grb2 complex and downstream Erk activation 48 .…”

“…Coinhibitory “checkpoints,” such as PD‐1 and its ligand PD‐L1, are considered to cause T‐cell exhaustion and terminally diminished adaptive immune response 53 . It was reported that inhibition of Cullin‐3 activity by MLN4924 attenuated T‐cell killing through blocked PD‐L1 protein degradation 54 . In view of intricate differentiation and function of adaptive immune cells, our knowledge of that of neddylation is far from being desired.…”