Project description:To find out potential mediators of PD-L1 lysosomal degradation, PD-L1 was immunoprecipitated and subjected to mass spectrometry analysis.
Project description:To clarify the potential BLIMP1 downstream target regulating PD-L1 expression, we performed proteomics analysis using BLIMP1 Hep3B cells and control cells. Proteomics analysis revealed that SPI1 may serve as a pivotal transcriptional factor that enhances PD-L1 expression by acting as a downstream effector of BLIMP1.
Project description:Disrupting PD-1/PD-L1 interaction rejuvenates antitumor immunity. Clinical successes by blocking PD-1/PD-L1 binding have grown across wide-ranging cancer histologies, but innate therapy resistance is evident in the majority of treated patients1. Cancer cells can express robust surface levels of PD-L1 to tolerize tumor-specific T cells, but regulation of PD-L1 protein levels in the cancer cell is poorly understood. Quasi-mesenchymal tumor cells up-regulate PD-L1/L2 and induce an immune-suppressive microenvironment, including expansion of M2-like macrophages and regulatory T cells and exclusion of CD8+ T-cell infiltration2. Targeted therapy, including MAPK inhibitor therapy in melanoma, leads to quasi-mesenchymal transitions and resistance3, and both MAPK inhibitor treatment and mesenchymal signatures are associated with innate anti-PD-1 resistance4,5. Here we identify ITCH as an E3 ligase that downregulates tumor cell-surface PD-L1/L2 in PD-L1/L2-high cancer cells, including MAPK inhibitor-resistant melanoma, and suppresses acquired MAPK inhibitor resistance in and only in immune-competent mice. ITCH interacts with and poly-ubiquitinates PD-L1/L2, and ITCH deficiency increases cell-surface PD-L1/L2 expression and reduces T cell activation. Mouse melanoma tumors grow faster with Itch knockdown only in syngeneic hosts but not in immune-deficient mice. MAPK inhibitor therapy induces tumor cell-surface PD-L1 expression in murine melanoma, recapitulating the responses of clinical melanoma3, and this induction is more robust with Itch knockdown. Notably, suppression of ITCH expression first elicits a shift toward an immune-suppressive microenvironment and then accelerates resistance development. These findings collectively identify ITCH as a critical negative regulator of PD-L1 tumor cell-surface expression and provide insights into previously unexplained role of PD-L1 in adaptive resistance to therapy.
Project description:Tumors expressing high level of programmed cell death-1 (PD-1) ligand 1 (PD-L1) are more likely to respond to immune checkpoint blockers (ICBs) targeting PD-1 or PD-L1. However, more than half of tumor patients with high PD-L1 expression does not respond to ICBs and the underlying mechanisms are yet to be clarified. Here we show that depletion of developmentally regulated GTP-binding protein 2 (DRG2) inhibited recycling of endosomal PD-L1 and reduced surface PD-L1 level in melanoma cells. DRG2-depleted cells showed decreased binding with recombinant PD-1. Although DRG2-depleted cells expressed high levels of PD-L1, anti-PD-1 ICB did not activate T cells within DRG2-depleted tumors and failed to improve the survival of DRG2-depleted tumor-bearing mice. Cohort analysis of melanoma patients under anti-PD-1 treatment revealed that patients bearing tumors with high DRG2 protein level were more sensitive to PD-1 anti-PD-1 ICBs. These findings identify DRG2 as a regulator of recycling of endosomal PD-L1 and a key determinant for response to anti-PD-1 ICB and provide insights into how to increase the correlation between PD-L1 expression and response to ICB.
Project description:Tumors expressing high level of programmed cell death-1 (PD-1) ligand 1 (PD-L1) are more likely to respond to immune checkpoint blockers (ICBs) targeting PD-1 or PD-L1. However, more than half of tumor patients with high PD-L1 expression does not respond to ICBs and the underlying mechanisms are yet to be clarified. Here we show that depletion of developmentally regulated GTP-binding protein 2 (DRG2) inhibited recycling of endosomal PD-L1 and reduced surface PD-L1 level in melanoma cells. DRG2-depleted cells showed decreased binding with recombinant PD-1. Although DRG2-depleted cells expressed high levels of PD-L1, anti-PD-1 ICB did not activate T cells within DRG2-depleted tumors and failed to improve the survival of DRG2-depleted tumor-bearing mice. Cohort analysis of melanoma patients under anti-PD-1 treatment revealed that patients bearing tumors with high DRG2 protein level were more sensitive to PD-1 anti-PD-1 ICBs. These findings identify DRG2 as a regulator of recycling of endosomal PD-L1 and a key determinant for response to anti-PD-1 ICB and provide insights into how to increase the correlation between PD-L1 expression and response to ICB.
Project description:This study aims to identify combination treatments capable of inducing improved IO responses in lung tumours and thus, help guide decisions on the next combination arms for the HUDSON trial (post-IO). For that purpose, a lung tumour GEMM model was treated with either vehicle, PD-L1, ATR, ATR/PD-L1; Cisplatin/PD-L1/Ctla4 or VEGFR/PD-L1 and tumours collected for transcriptional profiling.
Project description:Prostate cancers (PC) are largely unresponsive to immune checkpoint inhibitors and there is strong evidence that PD-L1 expression itself must be inhibited to activate anti-tumor immunity. Here, we report that neuropilin-2 (NRP2), which functions as a VEGF receptor on tumor cells, is an attractive target to activate anti-tumor immunity in prostate cancer because we demonstrate that VEGF/NRP2 signaling sustains PD-L1 expression. NRP2 depletion increased T cell activation in vitro. Inhibition of the binding of VEGF to NRP2 using a mouse specific anti-NRP2 mAb in a syngeneic model of prostate cancer that is resistant to checkpoint inhibition resulted in significant necrosis and tumor regression compared to both an anti-PD-L1 mAb and control IgG. This therapy also decreased tumor PD-L1 expression and increased immune cell infiltration. We also observed that the NRP2, VEGF-A, and VEGF-C genes are amplified in metastatic castration resistant and neuroendocrine prostate cancer (NEPC) and that NRP2high PD-L1high population in metastatic tumors had a significantly lower AR and higher NEPC scores than other populations. Therapeutic inhibition of VEGF binding to human NRP2 with a high affinity humanized mAb, which is suitable for clinical use, in organoids derived from NEPC patients also diminished PD-L1 expression and caused a significant increase in immune-mediated tumor cell killing consistent with the animal studies. These findings provide justification for the initiation of clinical trials using this novel function-blocking NRP2 mAb in prostate cancer, especially for patients with aggressive primary and metastatic cancers, where blocking NRP2-VEGF signaling shows potential in mitigating the morbidity and mortality associated with these cancers.
Project description:Tumor cells evade T cell-mediated immunosurveillance via the interaction between programmed death-1 (PD-1) ligand 1 (PD-L1) on tumor cells and PD-1 on T cells. Strategies disrupting PD-1/PD-L1 have shown clinical benefits in various cancers. However, the limited response rate prompts us to investigate the molecular regulation of PD-L1. Here we identify trafficking protein particle complex subunit 4 (TRAPPC4), a major player in vesicular trafficking, as a crucial PD-L1 regulator. TRAPPC4 interacts with PD-L1 in recycling endosomes, promoting RAB11-mediated recycling of PD-L1, and acting as a scaffold between PD-L1 and RAB11, thus replenishing its distribution on the tumor cell surface.