Programmed Death-ligand 1 Signaling Research Articles

Regulation of cervical cancer via G15-mediated inhibition of G protein-coupled estrogen receptor.

Cervical cancer is among the most common gynecological malignancies. G protein-coupled estrogen receptor (GPER) is involved in the development of various tumors; however, its role in cervical cancer remains unclear. We investigated whether G15, an inhibitor of GPER, can regulate its expression and affect cervical cancer progression. We examined the biological behaviors of G15-treated SiHa and HeLa cells using Cell Counting Kit-8, monoclonal proliferation, plate scratching, and Transwell invasion experiments. Western blotting was used to detect the expression of GPER, E-cadherin, N-cadherin, vimentin, Bcl-2, Bax, phosphatidylinositol-3-kinase (PI3K)/AKT, and programmed death ligand 1 (PD-L1). The expression of GPER, E-cadherin, vimentin, and PD-L1 in cervical cancer and adjacent tissues was detected using immunohistochemistry. The correlation between GPER expression and clinicopathological characteristics was analyzed. The expression of GPER in cervical cancer tissues was significantly higher than that in paracancerous tissues, and it was detected in the membrane and cytoplasm of SiHa and HeLa cells. The proliferation, migration, and invasion abilities of SiHa and HeLa cells were reduced after G15 treatment. The G15-treated groups exhibited higher expression of E-cadherin and Bax and lower expression of N-cadherin, vimentin, Bcl-2, GPER, p-PI3K, p-AKT, and PD-L1 than the control group. The expression of E-cadherin was lower and that of vimentin was higher in cancer tissues than in paracancerous tissues; PD-L1 was highly expressed in tumor and stromal cells in cancer tissues but not in paracancerous tissues. G15 functions by regulating the GPER/PI3K/AKT/PD-L1 signaling pathway and may serve as a new immunotherapy for treating patients with cervical cancer.

Tobacco-induced hyperglycemia promotes lung cancer progression via cancer cell-macrophage interaction through paracrine IGF2/IR/NPM1-driven PD-L1 expression

Tobacco smoking (TS) is implicated in lung cancer (LC) progression through the development of metabolic syndrome. However, direct evidence linking metabolic syndrome to TS-mediated LC progression remains to be established. Our findings demonstrate that 4-(methylnitrosamino)−1-(3-pyridyl)−1-butanone and benzo[a]pyrene (NNK and BaP; NB), components of tobacco smoke, induce metabolic syndrome characteristics, particularly hyperglycemia, promoting lung cancer progression in male C57BL/6 J mice. NB enhances glucose uptake in tumor-associated macrophages by increasing the expression and surface localization of glucose transporter (GLUT) 1 and 3, thereby leading to transcriptional upregulation of insulin-like growth factor 2 (IGF2), which subsequently activates insulin receptor (IR) in LC cells in a paracrine manner, promoting its nuclear import. Nuclear IR binds to nucleophosmin (NPM1), resulting in IR/NPM1-mediated activation of the CD274 promoter and expression of programmed death ligand-1 (PD-L1). Restricting glycolysis, depleting macrophages, or blocking PD-L1 inhibits NB-mediated LC progression. Analysis of patient tissues and public databases reveals elevated levels of IGF2 and GLUT1 in tumor-associated macrophages, as well as tumoral PD-L1 and phosphorylated insulin-like growth factor 1 receptor/insulin receptor (pIGF-1R/IR) expression, suggesting potential poor prognostic biomarkers for LC patients. Our data indicate that paracrine IGF2/IR/NPM1/PD-L1 signaling, facilitated by NB-induced dysregulation of glucose levels and metabolic reprogramming of macrophages, contributes to TS-mediated LC progression.

Hyaluronic acid hydrogel to modulate tumor cell clustering and programmed death ligand 1 signaling in cancer stem cells.

e14584 Background: The root of malignancy lies in the extracellular matrix (ECM) surrounding the stromal cells. Thus, current therapeutic targets manipulate abnormal tumor microenvironments (TME), which nourish cancer stem cells (CSC) and induce tumor cell clustering (TCC). Notably, despite the first line of clinical therapy with surgery and chemotherapy, uncontrolled self-renewal of CSCs, conversion of non-CSCs to CSCs, and TCC trigger cancer recurrence. The transmembrane glycoprotein CD44 is thought to be a potential master regulator in cancer recurrence as it interacts with hyaluronic acid (HA) in TME, expresses aberrantly on CSCs, induces TCC by homophilic interactions like Plakoglobin despite less understanding on their crosstalk, and promotes expression of pro-tumorigenic factor programmed death ligand 1 (PD-L1). Notably, CD44 is expressed in multiple isoforms, and splice isoform switching of CD44 dictates the properties of CSC, which still needs to be clarified. Hence, we aimed to characterize CSCs based on CD44 isoform expression, investigate the crosstalk between CD44 and Plakoglobin, and then design a novel injectable HA hydrogel that can disguise TME and suppress PD-L1 to combat cancer recurrence. Methods: To characterize CSCs, we prepared different scaffolds of HA of varied molecular weights and other ECM proteins, cultured cancer cells (MDA-MB-231, HeLa), and determined the expression of CD44 isoforms. We sorted CD44+/CD24- expressing CSC by flow cytometry. We implemented immunoprecipitation to detect the interaction between CD44 and Plakoglobin. We created a novel HA hydrogel composed of low and very high molecular weight HA, thiolated gelatin, and other components crosslinked with PEGDA. Using a torsional rheometer, we measured matrix stiffness. We assessed the cell proliferation efficiency of CSC by a colony-forming assay. Results: The study disclosed that CD44 isoforms expressed differently based on ECM properties. Matrix stiffness dictated CD44 isoform expression. We observed that CD44 interacted with Plakoglobin. CD44 ablation upregulated Plakoglobin significantly. Tumor suppressor p53 played a significant role in CD44-Plakoglobin crosstalk. We observed that the injectable hydrogel modulated CD44-Plakoglobin signaling and inhibited TCC, likely promoting anoikis. The hydrogel affected CD44 splicing and modified the activity of the CD44 intracellular domain, which interacts with PD-L1 and thus suppressed PD-L1 expression significantly in CSC. Conclusions: Currently, antibodies targeting PD-1/PD-L1 signaling have been clinically approved for various cancers. However, this regimen of treatment is expensive. We report a novel injectable hydrogel that can disguise TME, modulate CSCs and PD-L1, and may advance an alternative cost-effective avenue for cancer immunotherapy.

Absence of PD-L1 signaling hinders macrophage defense against Mycobacterium tuberculosis via upregulating STAT3/IL-6 pathway

The blockade of programmed death-ligand 1 (PD-L1) pathway has been clinically used in cancer immunotherapy, while its effects on infectious diseases remain elusive. Roles of PD-L1 signaling in the macrophage-mediated innate immune defense against M.tb is unclear. In this study, the outcomes of tuberculosis (TB) in wild-type (WT) mice treated with anti-PD-1/PD-L1 therapy and macrophage-specific Pdl1-knockout (Pdl1ΔΜΦ) mice were compared. Treatment with anti-PD-L1 or anti-PD-1 benefited protection against M.tb infection in WT mice, while Pdl1ΔΜΦ mice exhibited the increased susceptibility to M.tb infection. Mechanistically, the absence of PD-L1 signaling impaired M.tb killing by macrophages. Furthermore, elevated STAT3 activation was found in PD-L1-deficient macrophages, leading to increased interleukin (IL)-6 production and reduced inducible nitric oxide synthase (iNOS) expression. Inhibiting STAT3 phosphorylation partially impeded the increase in IL-6 production and restored iNOS expression in these PD-L1-deficient cells. These findings provide valuable insights into the complexity and mechanisms underlying anti-PD-L1 therapy in the context of tuberculosis.

Abstract PO1-07-04: Multiomics analysis reveals the landscape of PD-L1 expression in triple-negative breast cancer

Abstract Background: Tumor-infiltrating lymphocytes (TILs) and programmed death ligand 1 (PD-L1) remain controversial in predicting clinical outcomes of triple-negative breast cancer (TNBC), as outcomes do not always correlate with the expression of these biomarkers. Genomic and transcriptomic alterations that might contribute to the expression of these biomarkers remain incompletely uncovered. Methods: We evaluated PD-L1 immunohistochemistry (IHC) scores (SP142 and 28-8) and TILs in our TNBC multiomics dataset and two immunotherapy clinical trial cohorts. Then, we analyzed genomic and transcriptomic alterations correlated with TILs, PD-L1 expression and patient outcomes. Results: Despite TILs serving as a decent predictor for TNBC clinical outcomes, there remained exceptions. Our study revealed that several genomic alterations were correlated with unexpected events. Particularly, PD-L1 expression may cause a paradoxical relationship between TILs and prognosis in certain patients. Consequently, we classified TNBCs into four groups based on PD-L1 and TIL levels. The TIL-PD-L1+ and TIL+PD-L1- groups were not typical “hot” tumors; both were associated with worse prognoses and lower immunotherapy efficacy than TIL+PD-L1+ tumors. Copy number variation of PD-L1 and oncogenic signaling activation were correlated with PD-L1 expression in the TIL-PD-L1+ group, whereas GSK3B-induced degradation might cause undetectable PD-L1 expression in the TIL+PD-L1- group. These factors have the potential to affect the predictive function of both PD-L1 and TILs. Conclusions: Several genomic and transcriptomic alterations may cause paradoxical effects among TILs, PD-L1 expression and prognosis in TNBC. Investigating and targeting these factors will advance precision immunotherapy for TNBC patients. Keywords: Triple-negative breast cancer, PD-L1 expression, Tumor-infiltrating lymphocytes, Multiomics, Immunotherapy Citation Format: Han Wang, Xiao-Hong Ding, Cheng-Lin Liu, Yi Xiao, Ruo-Hong Shui, Yan-Ping Li, Chen Chen, Wen-Tao Yang, Zhi-Ming Shao, Yi-Zhou Jiang. Multiomics analysis reveals the landscape of PD-L1 expression in triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-07-04.

HMGB1 promotes neutrophil PD-L1 expression through TLR2 and mediates T cell apoptosis leading to immunosuppression in sepsis

Neutrophils and T lymphocytes are closely related to occurrence of immunosuppression in sepsis. Studies have shown that neutrophil apoptosis decreases and T lymphocyte apoptosis increases in sepsis immunosuppression, but the specific mechanism involved remains unclear. In the present study, we found Toll-like Receptor 2 (TLR2) and programmed death-ligand 1 (PD-L1) were significantly activated in bone marrow neutrophils of wild-type mice after LPS treatment and that they were attenuated by treatment with C29, an inhibitor of TLR2. PD-L1 activation inhibits neutrophil apoptosis, whereas programmed death protein 1 (PD-1)activation promotes apoptosis of T lymphocytes, which leads to immunosuppression. Mechanistically, when sepsis occurs, pro-inflammatory factors and High mobility group box-1 protein (HMGB1) passively released from dead cells cause the up-regulation of PD-L1 through TLR2 on neutrophils. The binding of PD-L1 and PD-1 on T lymphocytes leads to increased apoptosis of T lymphocytes and immune dysfunction, eventually resulting in the occurrence of sepsis immunosuppression. In vivo experiments showed that the HMGB1 inhibitor glycyrrhizic acid (GA) and the TLR2 inhibitor C29 could inhibit the HMGB1/TLR2/PD-L1 pathway, and improving sepsis-induced lung injury. In summary, this study shows that HMGB1 regulates PD-L1 and PD-1 signaling pathways through TLR2, which leads to immunosuppression.

Blocking senescence and tolerogenic function of dendritic cells induced by γδ Treg cells enhances tumor-specific immunity for cancer immunotherapy

BackgroundRegulatory T (Treg) cells are a key component in maintaining the suppressive tumor microenvironment and immune suppression in different types of cancers. A precise understanding of the molecular mechanisms used...

PD-L1 Expression Is Increased in LPS-Induced Acute Respiratory Distress Syndrome by PI3K-AKT-Egr-1/C/EBPδ Signaling Pathway.

The role of programmed death ligand 1 (PD-L1) has been extensively investigated in adaptive immune system. However, increasing data show that innate immune responses are also affected by the immune checkpoint molecule. It has been demonstrated that regulation of PD-L1 signaling in macrophages may be a potential therapeutic method for acute respiratory distress syndrome (ARDS). However, the PD-L1 expression pattern in local macrophages and whole lung tissues remains mysterious, hindering optimization of the potential treatment program. Therefore, we aim to determine the PD-L1 expression pattern during ARDS. Our findings show that PD-L1 levels are markedly increased in lipopolysaccharide (LPS)-stimulated lung tissues, which might be attributable to an increase in the gene expression by immune cells, including macrophages and neutrophils. In vitro experiments are performed to explore the mechanism involved in LPS-induced PD-L1 production. We find that PD-L1 generation is controlled by transcription factors early growth response 1 (Egr-1) and CCAAT/enhancer binding protein delta (C/EBPδ). Strikingly, PD-L1 production is enhanced by phosphoinositide-3 kinase (PI3K)-protein kinase B (AKT) signaling pathway via up-regulation of Egr-1 and C/EBPδ expressions. Additionally, we observe that expressions of Egr-1 and C/EBPδ mutually reinforce each other. Moreover, we observe that PD-L1 is protective for ARDS due to its regulatory role in macrophage-associated inflammatory response. In summary, during LPS-induced ARDS, PD-L1 expression, which is beneficial for the disease, is increased via the PI3K-AKT1-Egr-1/C/EBPδ signaling pathway, providing theoretical basis for application of methods controlling PD-L1 signaling in macrophages for ARDS treatment in clinic.

Identification of the functional PD-L1 interface region responsible for PD-1 binding and initiation of PD-1 signaling

The PD-1/PD-L1 checkpoint pathway is important for regulating immune responses and can be targeted by immunomodulatory drugs to treat a variety of immune disorders. However, the precise protein-protein interactions required for the initiation of PD-1/PD-L1 signaling are currently unknown. Previously, we designed a series of first-generation PD-1 targeting peptides based on the native interface region of programmed death ligand 1 (PD-L1) that effectively reduced PD-1/PD-L1 binding. In this work, we further characterized the previously identified lead peptide, MN1.1, to identify key PD-1 binding residues and design an optimized peptide, MN1.4. We show MN1.4 is significantly more stable than MN1.1 in serum and retains the ability to block PD-1/PD-L1 complex formation. We further characterized the immunomodulatory effects of MN1.4 treatment by measuring markers of T cell activation in a co-culture model with ovarian cancer cells and peripheral blood mononuclear cells. We found MN1.4 treatment reduced cytokine secretion and suppressed T cell responses in a similar manner as recombinant PD-L1. Therefore, the PD-L1 interface region used to design MN1.4 appeared sufficient to initiate PD-1 signaling and likely represents the minimum necessary region of PD-L1 required for PD-1 recognition. We propose a peptide agonist for PD-1, such as MN1.4, could have several applications for treating autoimmune disorders caused by PD-1 deficiencies such as type 1 diabetes, inflammatory arthritis, or autoimmune side effects arising from monoclonal antibody-based cancer immunotherapies.

PD-1/PD-L1 Interaction Upregulates YAP1 Expression in HepG2 Cells Through MAPK/ERK Pathway

Background Antibodies, which target programmed cell death protein-1 (PD-1) or its ligand programmed death ligand-1 (PD-L1), can rescue T cells from an exhausted state and resume their immune response to cancer cells. Clinically, the purpose of blocking the PD-1/PD-L1 signaling pathway is to induce immune cells to play an anti-tumor role. However, the effect of intertumor PD-1/PD-L1 signal blocking on tumor cells remains unclear. Methods HepG2 cells were treated with DHA, IFN-γ, BSA, DDP, PD-1-Fc (1 μg/ml), IgG-Fc, nivolumab, or human IgG for 24 h, respectively. GEPIA, cBioPortal, and TIMER databases were used to analyze the correlation between YAP1, PD-1, and PD-L1 and ERK, ERK-5, JNK, and p38. Western blot was used to detect the expression of YAP1 and p-ERK. Results GEPIA, cBioPortal, and TIMER databases analysis showed that YAP1 was positively correlated with ERK. After HepG2 cells were treated with PD98059 (ERK inhibitor), the expression of YAP1 was decreased. In this study, we investigated the inhibitory effect of PD98059 on PD-1/PD-L1 signaling. Our study found that PD-1-Fc (PD-1 fusion protein) promoted the expression of p-ERK/ERK and YAP1 in HepG2 cells. In contrast, nivolumab (PD-1 blocking antibody) reduced the expression of p-ERK/ERK and YAP1 in IFN-γ-pretreated HepG2 cells. In addition, the application of DHA also inhibited the expression of p-ERK/ERK to inhibit YAP1. Furthermore, treatment of HepG2 cells with DHA alone or DHA combined with cisplatin (DDP) both inhibited the expression of p-ERK/ERK and YAP1. Conclusions These results suggested that PD-1/PD-L1 interactions between tumor cells could promote the expression of ERK or YAP1 within tumors. Moreover, the conduction of PD-1/PD-L1 could be reversed using ERK inhibitors.

Elevated NOX4 promotes tumorigenesis and acquired EGFR-TKIs resistance via enhancing IL-8/PD-L1 signaling in NSCLC.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been widely used for human non-small-cell lung cancer (NSCLC) treatment. However, acquired resistance to EGFR-TKIs is the major barrier of treatment success, and new resistance mechanism remains to be elucidated. In this study, we found that elevated NADPH oxidase 4 (NOX4) expression was associated with acquired EGFR-TKIs resistance. Gefitinib is the first-generation FDA-approved EGFR-TKI, and osimertinib is the third-generation FDA-approved EGFR-TKI. We demonstrated that NOX4 knockdown in the EGFR-TKI resistant cells enabled the cells to become sensitive to gefitinib and osimertinib treatment, while forced expression of NOX4 in the sensitive parental cells was sufficient to induce resistance to gefitinib and osimertinib in the cells. To elucidate the mechanism of NOX4 upregulation in increasing TKIs resistance, we found that knockdown of NOX4 significantly down-regulated the expression of transcription factor YY1. YY1 bound directly to the promoter region of IL-8 to transcriptionally activate IL-8 expression. Interestingly, knockdown of NOX4 and IL-8 decreased programmed death ligand 1 (PD-L1) expression, which provide new insight on TKIs resistance and immune escape. We found that patients with higher NOX4 and IL-8 expression levels showed a shorter survival time compared to those with lower NOX4 and IL-8 expression levels in response to the anti-PD-L1 therapy. Knockdown of NOX4, YY1 or IL-8 alone inhibited angiogenesis and tumor growth. Furthermore, the combination of NOX4 inhibitor GKT137831 and gefitinib had synergistic effect to inhibit cell proliferation and tumor growth and to increase cellular apoptosis. These findings demonstrated that NOX4 and YY1 were essential for mediating the acquired EGFR-TKIs resistance. IL-8 and PD-L1 are two downstream targets of NOX4 to regulate TKIs resistance and immunotherapy. These molecules may be used as potential new biomarkers and therapeutic targets for overcoming TKIs resistance in the future.

Theprogrammed death ligand 1 interactome demonstrates bidirectional signaling coordinating immune suppression and cancer progression in head and neck squamous cell carcinoma.

The programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) are validated cancer targets; however, emerging mechanisms and impact of PD-L1 intracellular signaling on cancer behavior are poorly understood. We investigated the cancer cell intrinsic role of PD-L1 in multiple patient-derived models in vitro and in vivo. PD-L1 overexpression, knockdown, and PD-L1 intracellular domain (PD-L1-ICD) deletion (Δ260-290PD-L1) models were assessed for key cancer properties: clonogenicity, motility, invasion, and immune evasion. To determine how PD-L1 transduces signals intracellularly, we used the BioID2 platform to identify the PD-L1 intracellular interactome. Both human papillomavirus-positive and negative patient-derived xenografts were implanted in NOD-scid-gamma and humanized mouse models to investigate the effects of recombinant PD-1, anti-PD-L1, and anti-signal transducer and activator of transcription 3 (STAT3) in vivo. PD-L1 intracellular signaling increased clonogenicity, motility, and invasiveness in multiple head and neck squamous cell carcinoma (HNSCC) models, and PD-1 binding enhanced these effects. Protein proximity labeling revealed the PD-L1 interactome, distinct for unbound and bound PD-1, which initiated cancer cell-intrinsic signaling. PD-L1 binding partners interleukin enhancer binding factors 2 and 3 (ILF2-ILF3) transduced their effect through STAT3. Δ260-290PD-L1 disrupted signaling and reversed pro-growth properties. In humanized HNSCC in vivo models bearing T-cells, PD-1 binding triggered PD-L1 signaling, and dual PD-L1 and STAT3 inhibition were required to achieve tumor control. Upon PD-1 binding, the PD-L1 extracellular and intracellular domains exert a synchronized effect to promote immune evasion by inhibiting T-cell function while simultaneously enhancing cancer cell-invasive properties.

Tissue Age Affects Antigenicity and Scoring for the 22C3 Immunohistochemistry Companion Diagnostic Test

Programmed death-ligand 1 (PD-L1) antibody 22C3 is the approved companion diagnostic immunohistochemistry test for treatment with pembrolizumab and cemiplimab in multiple cancer types. The 22C3 and 28-8 antibodies target the extracellular domain (ECD) of PD-L1, which is known to contain N-glycosylation sites. We hypothesize that antigenicity could be affected by the degradation of the glycan part of the epitope and thus change the scoring of the assay over time. Here, we test samples over time and assess the effects of time and deglycosylation on PD-L1 signal by comparing an antibody with an ECD antigen to an antibody with an intracellular domain (ICD) antigen. Ten whole-tissue sections of non–small-cell lung cancer (NSCLC) from 2018 were selected for testing. Fresh-cut serial sections for each case were stained on DAKO Link48 for 22C3 according to the label. In parallel, a previously described laboratory-developed test using E1L3N (an ICD antibody) was performed on the Leica BondRX. Tumor proportion scores for 22C3 and E1L3N were read by a pathologist and compared to the previous clinical diagnoses. To determine the effect using a quantitative approach, a tissue microarray (TMA) cohort with 90 NSCLC cases was similarly assessed. Finally, to determine whether the possible effect of epitope glycosylation, antibodies were tested before and after enzymatic deglycosylation of specimens. We found that 6 of 7 archival positive samples showed a significant reduction in positive staining with 22C3 compared to the original diagnostic sample assessed 3 years earlier. In an older archival TMA cohort, a quantitative significant difference in signal intensity was noted when staining with 22C3 was compared to E1L3N. This loss of signal was not noted in the fresh cell line TMA consistent with a time-dependent degradation of staining. Finally, quantitative assessment of the fresh TMA showed a significant loss of signal after a deglycosylation procedure when stained with 22C3, which was not seen when stained with E1L3N. We believe that these data show that the glycan part of the 22C3 epitope is not stable over time, and that this issue should be considered when assessing archival tissue for diagnostic or research purposes.

Discovery of potential PD-L1 small molecule inhibitors as novel cancer therapeutics using machine learning-based QSAR models: A virtual drug repurposing study.

Binding of programmed death 1 (PD-1) to programmed death ligand-1 (PD-L1) triggers downstream signaling pathways and results in inhibition of new cytotoxic T-cell activation. Cancer cells can “trick” the immune system with the T-cell suppression ability of the PD-1/PD-L1 signaling mechanism. Blocking the PD-1/PD-L1 interaction through target-specific small molecules can recruit cytotoxic T cells and reactivate the immune response, is a potential therapy in many types of cancer. In spite of that, there are currently no approved small molecule inhibitors targeting the PD-1/PD-L1 pathway. In this study, we aim to discover target-specific and effective small molecules with anti-cancer activity. With this objective, we performed a virtual drug repurposing study on PD1 protein, PD1-PDL1 structure and PDL1-PDL1 homodimer complexes. The results revealed that PDL1-dimer structure is the most suitable target model for virtual screening of small molecule inhibitors. Three different approaches with different algorithms were used in virtual screening to discover the best hit molecules: (i) structure-based, (ii) structure-based pharmacophore (hybrid) and (iii) machine learning-based QSAR. At the end of the study, which included three different approaches, promising PDL1 small molecule inhibitors such as anidulafungin, bemotrizinol, deferoxamine, dequalinium, neratinib, ubiquinol and vilanterol were discovered.

Effect of MiR-424-5p on the Drug Resistance of Diffuse Large B-Cell Lymphoma Cells by Regulating PD-1/PD-L1 Signaling Pathway

To explore the effect of microRNA-424-5p (miR-424-5p) on the drug resistance of diffuse large B-cell lymphoma (DLBCL) cells by regulating the programmed death receptor-1 (PD-1)/programmed death ligand-1 (PD-L1) signaling pathway. Human DLBCL cell line CRL2631 cells were induced to construct CRL2631-CHOP resistant cell line. RT-qPCR and Western blot were used to detect the expression levels of MiR-424-5p, PD-L1 mRNA and protein, and multidrug resistance gene-1 (MDR-1) protein in CRL2631 cells and CRL2631-CHOP cells, respectively. The target genes of MiR-424-5p was verified by dual luciferase reporter assay. The miRNA simulation/interference technology and thiazole blue (MTT) method were used to detect the resistance of CRL2631 cells and CRL2631-CHOP cells to CHOP. Compared with CRL2631 cells, the drug resistance of CRL2631-CHOP cells to CHOP and the levels of MDR-1 protein (P<0.05), PD-L1 mRNA and protein in the cells were significantly increased (both P<0.001), while the relative level of MiR-424-5p was significantly reduced (P<0.001). The result of the dual luciferase reporter assay showed that PD-L1 was the direct downstream target gene of MiR-424-5p (P<0.001). After transfection of MiR-424-5p inhibitor, the resistance of CRL2631 cells to CHOP drugs increased, and the expression level of MDR-1 protein (P<0.01), PD-L1 mRNA and protein also increased significantly (both P<0.01). After transfection of MiR-424-5p mimics, the resistance of CRL2631-CHOP cells to CHOP drugs decreased, and the expression level of MDR-1 protein (P<0.001), PD-L1 mRNA and protein also decreased significantly (both P<0.001). Overexpression of PD-L1 could reverse the inhibitory effect of upregulating MiR-424-5p on PD-L1 (P<0.001). Down-regulation of MiR-424-5p enhances the drug resistance of DLBCL cells by regulating the PD-1/PD-L1 signaling pathway.

Research progress on the intrinsic non-immune function of PD-L1 in tumors (Review).

Programmed death ligand 1 (PD-L1) is widely expressed in human tumors. It is widely known for its immunosuppressive function as it can help tumor cells evade T cell immune killing through the PD-1/PD-L1 signal. A number of clinical trials have proved that the destruction of the combination of PD-1 and PD-L1 by antibodies could significantly affect patients with advanced cancer. However, a number of patients with cancer still cannot benefit from PD-1/PD-L1 blocking therapy. The main reason is that PD-L1 also has some intrinsic regulatory functions to promote the progression of tumors. PD-L1 Protein contains an intrinsic domain that could link to other signal pathways, but the mechanism has not yet been fully revealed. The present review mainly discussed the non-immune checkpoint functions of PD-L1, such as its role in regulating cell proliferation, cell metabolism, drug resistance and maintaining epithelial-mesenchymal transition and stemness.

Nanobubbles containing PD-L1 Ab and miR-424 mediated PD-L1 blockade, and its expression inhibition to enable and potentiate hepatocellular carcinoma immunotherapy in mice

Immune checkpoint inhibitors (ICI) therapy is the main type of immunotherapy for cancer. Current clinical trials are focused on enhancing anti-tumor effects through combinations of multiple ICIs with agents that cause tumor cell death and release tumor antigens. In this study, weprepared nanobubbles (NBs) to load programmed death-ligand 1 (PD-L1) antibody andmiR-424gene to evaluate the combined anti-tumor activity of the targeted NBs.The miR-424 gene was chosen to be an anti-tumor gene, which can target PD-L1 and Bcl-2, through bioinformatics analysis and target gene verification. Then, PD-L1 Ab/miR-424-NBs were prepared by thin-film hydration. The optimal shape, size, and character of the NBs were determined by scanning electron microscopy and Zeta potential study. In addition, the antibody binding rate and gene loading of the targeted NBs were studied by agarose gel electrophoresis and flow cytometry, respectively. The synergistic immunotherapeutic effect of anti-PD-L1 antibody andmiR-424in vivo and their mechanism were evaluated using an H22 hepatoma transplanted tumor model in mice,whichproved that the targeted NBs mediated the PD-L1 antibody toblock the PD-1/PD-L1 signaling pathway and the transfected miR-424gene to downregulate the PD-L1 expression of tumor cells, both of which enhanced the antitumor immune effect mediated by T cells. It was also found that the targeted NBs activated T cells, which released a large number of cytokines, such as IFN-γ and IL-2, to recruit and activate macrophages and NK cells. It is suggested that ultrasound-mediated PD-L1 antibody NBs delivering miR-424 can inhibit the growth of subcutaneously transplanted hepatocellular carcinoma in terms of apoptosis and immunity. Therefore, ultrasound-mediated targeted NBs are a potential effective carrier for liver cancer, and PD-L1 antibody and miR-424 have a synergistic anti-tumor immunotherapy effect.

PD-1/PD-L1 Inhibition Enhances Chemotherapy-Induced Neuropathic Pain by Suppressing Neuroimmune Antinociceptive Signaling.

Cytotoxic agents synergize with immune checkpoint inhibitors and improve outcomes for patients with several cancer types. Nonetheless, a parallel increase in the incidence of dose-limiting side effects, such as peripheral neuropathy, is often observed. Here, we investigated the role of the programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis in the modulation of paclitaxel-induced neuropathic pain. We found that human and mouse neural tissues, including the dorsal root ganglion (DRG), expressed basal levels of PD-1 and PD-L1. During the development of paclitaxel-induced neuropathy, an increase in PD-L1 expression was observed in macrophages from the DRG. This effect depended on Toll-like receptor 4 activation by paclitaxel. Furthermore, PD-L1 inhibited pain behavior triggered by paclitaxel or formalin in mice, suggesting that PD-1/PD-L1 signaling attenuates peripheral neuropathy development. Consistent with this, we observed that the combined use of anti-PD-L1 plus paclitaxel increased mechanical allodynia and chronic neuropathy development induced by single agents. This effect was associated with higher expression of inflammatory markers (Tnf, Il6, and Cx3cr1) in peripheral nervous tissue. Together, these results suggest that PD-1/PD-L1 inhibitors enhance paclitaxel-induced neuropathic pain by suppressing PD-1/PD-L1 antinociceptive signaling.

Disrupting the Interplay between Programmed Cell Death Protein 1 and Programmed Death Ligand 1 with Spherical Nucleic Acids in Treating Cancer.

Disrupting the interplay between programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) is a powerful immunotherapeutic approach to cancer treatment. Herein, spherical nucleic acid (SNA) liposomal nanoparticle conjugates that incorporate a newly designed antisense DNA sequence specifically against PD-L1 (immune checkpoint inhibitor SNAs, or IC-SNAs) are explored as a strategy for blocking PD-1/PD-L1 signaling within the tumor microenvironment (TME). Concentration-dependent PD-L1 silencing with IC-SNAs is observed in MC38 colon cancer cells, where IC-SNAs decrease both surface PD-L1 (sPD-L1) and total PD-L1 expression. Furthermore, peritumoral administration of IC-SNAs in a syngeneic mouse model of MC38 colon cancer leads to reduced sPD-L1 expression in multiple cell populations within the TME, including tumor cells, dendritic cells, and myeloid derived suppressor cells. The treatment effectively increases CD8+ T cells accumulation and functionality in the TME, which ultimately inhibits tumor growth and extends animal survival. Taken together, these data show that IC-SNA nanoconstructs are capable of disrupting the PD-1/PD-L1 interplay via gene regulation, thereby providing a promising avenue for cancer immunotherapy.

Abstract 5624: PD-L1 mediates IFNγ-regulation of glucose but not of tryptophan metabolism in clear cell renal cell carcinoma

Abstract The immune checkpoint programmed death-ligand 1 (PD-L1) is expressed on the cell surface of tumor cells and is key for maintaining an immunosuppressive microenvironment through its interaction with the programmed cell death 1 (PD-1). Clear cell renal cell carcinoma (ccRCC) is a highly immunogenic cancer characterized by an aberrant aerobic glycolytic metabolism and is known to overexpress PD-L1. Multiple immunotherapies have been approved for the treatment of ccRCC, including cytokines and immune checkpoint inhibitors. Recently the intrinsic role of PD-L1 and interferon gamma (IFNγ) signaling have been studied in several types of tumor cells, yet it remains unclear how they affect the metabolism and signaling pathways of ccRCC. Using metabolomics, metabolic assays and RNAseq, we showed that IFNγ enhanced aerobic glycolysis and tryptophan metabolism in ccRCC cells in vitro and induced the transcriptional expression of signaling pathways related to inflammation, cell proliferation and cellular energetics. These metabolic and transcriptional effects were partially reversed following PD-L1 transient silencing. Aerobic glycolysis as well as signaling pathways related to inflammation were not induced by IFNγ when PD-L1 was silenced, however tryptophan metabolism and activation of Jak2 and STAT1 were maintained. Our data demonstrate that PD-L1 expression is required to mediate some of IFNγ’s effect in ccRCC cells and highlight the importance of PD-L1 signaling in regulating the metabolism of ccRCC cells in response to inflammatory signals. Citation Format: Mamatha Garige, Susmita Ghosh, ALexis Norris, Guangyuan Li, Carole Sourbier. PD-L1 mediates IFNγ-regulation of glucose but not of tryptophan metabolism in clear cell renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5624.