Upregulation Of Programmed Death-ligand 1 Research Articles

Abstract A038: Investigating PD-L1 status in circulating tumor cells isolated from blood samples of lung cancer patients

Abstract Background: This research study aimed to assess the performance of a research use only (RUO) immunofluorescence (IF) assay targeting programmed death-ligand 1 (PD-L1) evolution in epithelial and/or mesenchymal circulating tumor cells (CTCs) isolated from blood using Parsortix® microfluidic technology. Upregulation of PD-L1 enables cancer cells to evade the host immune response. Assessment of PD-L1 status in the tumor, as determined by traditional tissue biopsy, can indicate if immunotherapy has the potential to be an effective treatment. However, PD-L1 expression in tumor biopsies may not reflect metastatic sites in their entirety and can become outdated during tumor evolution, as the process cannot be repeated due its invasive nature. Liquid biopsy offers a minimally invasive option for dynamic testing of PD-L1 in CTCs as patients undergo treatment. Methods: Analytical linearity, and specificity and sensitivity were assessed by spiking HCC1954 and Hs 578T cancer cell lines into the blood samples of 34 healthy volunteers. The assay was then evaluated in samples from 47 metastatic lung cancer patients, among which 32 had a known PD-L1 tissue status (19 positive, 13 negative). Up to six successive draws were taken for each patient, collected into Streck Cell-Free DNA blood collection tubes. ANGLE’s Parsortix® instruments were used to isolate spiked cancer cells or CTCs from blood samples based on their size and deformability. The CTC- enriched harvests were processed onto ANGLE’s CellKeepTM slides and IF stained with ANGLE’s Portrait® PD-L1 RUO assay for PD-L1 identification on CTCs. Slides were imaged on a BioView automated imaging system. Results: Analytical specificity of PD-L1 was 98% and analytical sensitivity was 81%. Analytical linearity (R2=0.91) was shown over a 0–500 cells range. In metastatic lung cancer patients, ≥1 CTC was identified in at least one draw for 91% of donors, with 55% of those donors exhibiting ≥1 PD-L1 positive CTC. A majority (81%) of donors exhibited a positive correlation between PD-L1 tissue status and CTC expression. However, the remaining 19% of donors exhibited discordance with a PD-L1 negative tissue status but PD-L1 positivity identified in ≥1 CTC. Of the PD-L1 positive CTCs identified, 98% expressed mesenchymal markers. Dynamic change was shown in all but one donor, with PD-L1 status of the CTCs changing over time. Conclusions: This study demonstrated the ability to determine PD-L1 status in CTCs from the blood of metastatic lung cancer patients and, subject to further study, the future potential to develop dynamic PD-L1 testing for advancement of more personalized cancer treatments. Patients with a PD-L1 negative tissue status exhibited PD-L1 positive CTCs, demonstrating the feasibility of a more repeatable and accurate assessment of PD-L1 status than can be achieved through a traditional tissue biopsy. Citation Format: Morgan Spode, Chloe Goodwin, Aarabhi Varatharajah, Aaron Cottingham, Elisha Duhig, Laura Kaja, David Greaves, Mariacristina Ciccioli, Anne-Sophie Pailhes-Jimenez. Investigating PD-L1 status in circulating tumor cells isolated from blood samples of lung cancer patients [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A038.

Leveraging chemotherapy-induced PD-L1 upregulation to potentiate targeted PD-L1 degradation using nanoparticle-based targeting chimeras

The combination of nab-paclitaxel and the programmed death-ligand 1(PD-L1) antibody atezolizumab showed limited benefits in clinical trials involving PD-L1-positive triple-negative breast cancer patients. This observed lack of success is attributed to the upregulation of PD-L1 on tumor cells induced by paclitaxel, leading to resistance against PD-L1 antibodies. Here, we introduce nanoparticle-based PD-L1 targeting chimeras (NanoTACPD-L1) to induce PD-L1 degradation instead of blockade. NanoTACPD-L1 initiates endocytosis independent of specific lysosome-targeting receptors, and delivers membrane-bound PD-L1 to lysosomes for targeted degradation. Furthermore, the efficiency of degradation is directly correlated with the PD-L1 expression level. NanoTACPD-L1 effectively leverages paclitaxel-induced PD-L1 upregulation to enhance PD-L1 degradation, employing a “Meet-Plot-With-Plot” strategy. In a series of in vivo models, NanoTACPD-L1 demonstrates superior therapeutic efficacy and immune activation, both when administered individually and in combination with paclitaxel, surpassing the effects of anti-PD-L1 antibody treatment. Collectively, our study provides a nanotechnology-based tool that can be enhanced by paclitaxel for PD-L1 degradation and validates its potential application in overcoming chemo-immunotherapy resistance.

Cancer cell-specific PD-L1 expression is a predictor of poor outcome in patients with locally advanced oral cavity squamous cell carcinoma

BackgroundLocally advanced oral cavity squamous cell carcinoma (OCSCC) presents a significant clinical challenge despite being partially responsive to standard treatment modalities. This study investigates the prognostic implications of programmed death-ligand...

PD-L1 induces autophagy and primary resistance to EGFR–TKIs in EGFR-mutant lung adenocarcinoma via the MAPK signaling pathway

Resistance to epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitors (TKIs) is a significant cause of treatment failure and cancer recurrence in non-small cell lung cancer (NSCLC). Approximately 30% of patients with EGFR-activating mutations exhibit primary resistance to EGFR–TKIs. However, the potential mechanisms of primary resistance to EGFR–TKIs remain poorly understood. Recent studies have shown that increased expression of programmed death ligand-1 (PD-L1) is associated with EGFR–TKIs resistance. Therefore, the present study aimed to investigate the mechanism of PD-L1 in primary resistance to EGFR–TKIs in EGFR-mutant lung adenocarcinoma (LUAD) cells. We found that PD-L1 was associated with poor prognosis in patients with EGFR-mutant LUAD, while the combination of EGFR–TKIs with chemotherapy could improve its therapeutic efficacy. In vitro and in vivo experiments revealed that PD-L1 promoted the proliferation and autophagy and inhibited the apoptosis of LUAD cells. Mechanistic studies demonstrated that upregulation of PD-L1 was critical in inducing autophagy through the mitogen-activated protein kinase (MAPK) signaling pathway, which was beneficial for tumor progression and the development of gefitinib resistance. Furthermore, we found that gefitinib combined with pemetrexed could synergistically enhance antitumor efficacy in PD-L1-overexpression LUAD cells. Overall, our study demonstrated that PD-L1 contributed to primary resistance to EGFR–TKIs in EGFR-mutant LUAD cells, which may be mediated by inducing autophagy via the MAPK signaling pathway. These findings not only help improve the prognosis of patients with EGFR-mutant LUAD but also provide a reference for the research of other cancer types.

Peptide-based immuno-PET/CT monitoring of dynamic PD-L1 expression during glioblastoma radiotherapy

Real-time, noninvasive programmed death-ligand 1 (PD-L1) testing using molecular imaging has enhanced our understanding of the immune environments of neoplasms and has served as a guide for immunotherapy. However, the utilization of radiotracers in the imaging of human brain tumors using positron emission tomography/computed tomography (PET/CT) remains limited. This investigation involved the synthesis of [18F]AlF-NOTA-PCP2, which is a novel peptide-based radiolabeled tracer that targets PD-L1, and evaluated its imaging capabilities in orthotopic glioblastoma (GBM) models. Using this tracer, we could noninvasively monitor radiation-induced PD-L1 changes in GBM. [18F]AlF-NOTA-PCP2 exhibited high radiochemical purity (>95%) and stability up to 4 hours after synthesis. It demonstrated specific, high-affinity binding to PD-L1 in vitro and in vivo, with a dissociation constant of 0.24 nM. PET/CT imaging, integrated with contrast-enhanced magnetic resonance imaging, revealed significant accumulation of [18F]AlF-NOTA-PCP2 in orthotopic tumors, correlating with blood–brain barrier disruption. After radiotherapy (15 Gy), [18F]AlF-NOTA-PCP2 uptake in tumors increased from 9.51% ± 0.73% to 12.04% ± 1.43%, indicating enhanced PD-L1 expression consistent with immunohistochemistry findings. Fractionated radiation (5 Gy × 3) further amplified PD-L1 upregulation (13.9% ± 1.54% ID/cc) compared with a single dose (11.48% ± 1.05% ID/cc). Taken together, [18F]AlF-NOTA-PCP2 may be a valuable tool for noninvasively monitoring PD-L1 expression in brain tumors after radiotherapy.

Unveiling the regulatory mechanism of nimotuzumab on PD-L1 expression in head and neck squamous cell carcinoma patients: Implications for enhanced anticancer treatment strategies

The overexpression of programmed death ligand 1 (PD-L1) is associated with resistance to anticancer therapies and poor prognosis in patients with head and neck squamous cell carcinoma (HNSCC). Nimotuzumab, a humanized anti-epidermal growth factor receptor (EGFR) mAb, has been widely used clinically for treating several solid tumors. However, whether its anticancer effect involves a reduction in PD-L1 expression remains unclear. The current study aimed to investigate the regulatory effects and underlying mechanism of nimotuzumab on PD-L1 expression in HNSCC both in vitro and in vivo. In vitro, nimotuzumab inhibited IFN-γ-induced PD-L1 upregulation at both the transcriptional and protein levels in the HNSCC cell lines. Subsequent mechanism research revealed that nimotuzumab suppressed IFN-γ-stimulated PD-L1 upregulation mainly by inhibiting phosphorylation of EGFR/MEK/ERK pathway, which was further validated by MEK and ERK inhibitors. In a HNSCC tumor-bearing model, nimotuzumab significantly decreased PD-L1 expression during tumor progression or chemotherapy, and this reduction was accompanied by increased sensitivity of the tumor to docetaxel and atezolizumab. Additionally, nimotuzumab reversed PD-L1 upregulation when combined with Taxol + Cisplatin (TP) induction chemotherapy regimens and improved the CD4+ and CD8+ T cells infiltration in HNSCC patients. These findings provide new insights into the anticancer mechanisms of nimotuzumab in HNSCC.

Human cytomegalovirus UL23 exploits PD-L1 inhibitory signaling pathway to evade T cell-mediated cytotoxicity.

T cell immunity is pivotal in controlling primary human cytomegalovirus (HCMV) infection, restricting periodic reactivation, and preventing HCMV-associated diseases. Despite inducing a robust T cell immune response, HCMV has developed sophisticated immune evasion mechanisms that specifically target T cell responses. Although numerous studies have been conducted on HCMV-specific T cells, the primary focus has been on the impact of HCMV on T cell recognition via major histocompatibility complex molecules. Our studies show for the first time that HCMV exploits the programmed death ligand 1 (PD-L1) inhibitory signaling pathway to evade T cell immunity by modulating the activities of T cells and thereby blocking the secretion of IFN-γ, which is directly mediated by HCMV-encoded tegument protein UL23. While PD-L1 has been extensively studied in the context of tumors and viruses, its involvement in HCMV infection and viral immune evasion is rarely reported. We observed an upregulation of PD-L1 in normal cells during HCMV infection and provided strong evidence supporting its critical role in UL23-induced inhibition of T cell-mediated cytotoxicity. The novel strategy employed by HCMV to manipulate the inhibitory signaling pathway of T cell immune activation for viral evasion through its encoded protein offers valuable insights for the understanding of HCMV-mediated T cell immunomodulation and developing innovative antiviral treatment strategies.

Treg-derived TGF-β1 dampens cGAS-STING signaling to downregulate the expression of class I MHC complex in multiple myeloma

Multiple myeloma (MM) progression involves diminished tumor antigen presentation and an immunosuppressive microenvironment, characterized by diminished expression of major histocompatibility complexes (MHC) class I molecule and elevated programmed death ligand 1 (PDL1) in MM cells, along with an enriched population of regulatory T cells (Tregs). To investigate Treg's influence on MM cells, we established a co-culture system using Tregs from MM patients and the MM cell lines (MM.1S and SK-MM-1) in vitro and assessed the effects of intervening in the relevant pathways connecting Tregs and MM cells in vivo. In vitro, Tregs induced transforming growth factor beta-1 (TGF-β1) production, downregulated MHC I members, and increased PDL1 expression in MM cells. Treg-derived TGF-β1 suppressed the cGAS-STING pathway, contributing to the loss of MHC I molecule expression and PDL1 upregulation. Correspondingly, neutralizing TGF-β1 or activating the cGAS-STING pathway restored MHC I and PDL1 expression, effectively countering the pro-tumorigenic effect of Tregs on MM cells in vivo. These data elucidated how Tregs influence tumor antigen presentation and immunosuppressive signal in MM cells, potentially providing therapeutic strategies, such as neutralizing TGF-β1 or activating the cGAS-STING pathway, to address the immune escape and immunosuppressive dynamics in MM.

M1A inhibition fuels oncolytic virus-elicited antitumor immunity via downregulating MYC/PD-L1 signaling

N1-methyladenosine (m1A) RNA methylation is critical for regulating mRNA translation; however, its role in the development, progression, and immunotherapy response of head and neck squamous cell carcinoma (HNSCC) remains largely unknown. Using Tgfbr1 and Pten conditional knockout (2cKO) mice, we found the neoplastic transformation of oral mucosa was accompanied by increased m1A modification levels. Analysis of m1A-associated genes identified TRMT61A as a key m1A writer linked to cancer progression and poor prognosis. Mechanistically, TRMT61A-mediated tRNA-m1A modification promotes MYC protein synthesis, upregulating programmed death-ligand 1 (PD-L1) expression. Moreover, m1A modification levels were also elevated in tumors treated with oncolytic herpes simplex virus (oHSV), contributing to reactive PD-L1 upregulation. Therapeutic m1A inhibition sustained oHSV-induced antitumor immunity and reduced tumor growth, representing a promising strategy to alleviate resistance. These findings indicate that m1A inhibition can prevent immune escape after oHSV therapy by reducing PD-L1 expression, providing a mutually reinforcing combination immunotherapy approach.

Transmural Flow Upregulates PD-L1 Expression in Microvascular Networks.

Endothelial programmed death-ligand 1 (PD-L1) expression is higher in tumors than in normal tissues. Also, tumoral vasculatures tend to be leakier than normal vessels leading to a higher trans-endothelial or transmural fluid flow. However, it is not clear whether such elevated transmural flow can control endothelial PD-L1 expression. Here, a new microfluidic device is developed to investigate the relationship between transmural flow and PD-L1 expression in microvascular networks (MVNs). After treating the MVNs with transmural flow for 24h, the expression of PD-L1 in endothelial cells is upregulated. Additionally, CD8 T cell activation by phytohemagglutinin (PHA) is suppressed when cultured in the MVNs pre-conditioned with transmural flow. Moreover, transmural flow is able to further increase PD-L1 expression in the vessels formed in the tumor microenvironment. Finally, by utilizing blocking antibodies and knock-out assays, it is found that transmural flow-driven PD-L1 upregulation is controlled by integrin αVβ3. Overall, this study provides a new biophysical explanation for high PD-L1 expression in tumoral vasculatures.

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.

Acesulfame potassium upregulates PD-L1 in HCC cells by attenuating autophagic degradation

Artificial sweeteners, which contain no or few calories, have been widely used in various foods and beverages, and are regarded as safe alternatives to sugar by the Food and Drug Administration. While several studies suggest that artificial sweeteners are not related to cancer development, some research has reported their potential association with the risk of cancers, including hepatocellular carcinoma (HCC). Here, we investigated whether acesulfame potassium (Ace K), a commonly used artificial sweetener, induces immune evasion of HCC cells by upregulating programmed death ligand-1 (PD-L1). Ace K elevated the protein levels of PD-L1 in HCC cells without increasing its mRNA levels. The upregulation of PD-L1 protein levels in HCC cells by Ace K was induced by attenuated autophagic degradation of PD-L1, which was mediated by the Ace K-stimulated ERK1/2-mTORC1 signaling pathway. Ace K-induced upregulation of PD-L1 attenuated T cell-mediated death of HCC cells, thereby promoting immune evasion of HCC cells. In summary, the present study suggests that Ace K promotes HCC progression by upregulating the PD-L1 protein level.

Hexavalent chromium exposure activates the non-canonical nuclear factor kappa B pathway to promote immune checkpoint protein programmed death-ligand 1 expression and lung carcinogenesis

Lung cancer is the leading cause of cancer-related death worldwide; however, the mechanism of lung carcinogenesis has not been clearly defined. Chronic exposure to hexavalent chromium [Cr(VI)], a common environmental and occupational pollutant, causes lung cancer, representing an important lung cancer etiology factor. The mechanism of how chronic Cr(VI) exposure causes lung cancer remains largely unknown. By using cell culture and mouse models and bioinformatics analyses of human lung cancer gene expression profiles, this study investigated the mechanism of Cr(VI)-induced lung carcinogenesis. A new mouse model of Cr(VI)-induced lung carcinogenesis was developed as evidenced by the findings showing that a 16-week Cr(VI) exposure (CaCrO4, 100 μg per mouse once per week) via oropharyngeal aspiration induced lung adenocarcinomas in male and female A/J mice, whereas none of the sham-exposed control mice had lung tumors. Mechanistic studies revealed that chronic Cr(VI) exposure activated the non-canonical NFκB pathway through the long non-coding RNA (lncRNA) ABHD11-AS1/deubiquitinase USP15-mediated tumor necrosis factor receptor-associated factor 3 (TRAF3) down-regulation. The non-canonical NFκB pathway activation increased the interleukin 6 (IL-6)/Janus kinase (Jak)/signal transducer and activator of transcription 3 (Stat3) signaling. The activation of the IL-6/Jak signaling axis by Cr(VI) exposure not only promoted inflammation but also stabilized the immune checkpoint molecule programmed death-ligand 1 (PD-L1) protein in the lungs, reducing T lymphocyte infiltration to the lungs. Given the well-recognized critical role of PD-L1 in inhibiting anti-tumor immunity, these findings suggested that the lncRNA ABHD11-AS1-mediated non-canonical NFκB pathway activation and PD-L1 up-regulation may play important roles in Cr(VI)-induced lung carcinogenesis.

Abstract 100: Blockade of CCL5 and CXCL10 signaling as a novel immunotherapy for epithelial ovarian cancer

Abstract Background: Cancer immune evasion remains a major barrier in developing enduring therapies for epithelial ovarian cancer (EOC). Expression of programmed death-ligand 1 (PD-L1) is known for its immunosuppressive role in cancer, thus interferences to PD-L1 have shown marked efficacy against many advanced cancers. However, the mechanisms by which PD-L1-negative cancers evade immune response remain unelucidated. We have found chemokine (C-C motif) ligand 5 (CCL5) and (C-X-C motif) ligand 10 (CXCL10) to up-regulate in PD-L1-negative EOC. Therefore, the present study aims to investigate blockade of CCL5/CXCL10 signaling to overcome immune evasion of EOC. Methods: Isogenic BRCA2-mutated PEO1 and BRCA2-wild type PEO4 EOC cells were treated with IFNγ, olaparib, or both in combination for western blot and flow cytometric analyses of PD-L1 expression. The conditioned medium of PEO1 and PEO4 cells was analyzed for immune array analysis to determine and compare the levels of 36 cytokines. PEO1 and PEO4 cells were co-cultured with CD3/CD28 antibodies-activated human peripheral blood mononuclear cells (PBMCs). Then, PBMCs were stained with anti-CD8 or CD4 and CD25 antibodies for flow cytometric analyses of cytotoxic or helper T cells, respectively. PEO1 and PEO4 cells were co-cultured with activated PBMCs in the presence and absence of TAK-779 or AMG-487. Thereafter, PBMCs were stained with anti-CD4, CD25, and FOXP3 antibodies for flow cytometric analyses of regulatory T cells (Tregs). PEO1 and PEO4 cells were transfected with CCL5- or CXCL10-siRNA and subsequently co-cultured with activated SUPT1 cells or PBMCs. The conditioned medium was collected and analyzed for the levels of IFNγ by ELISA. Results: PEO1 cells exhibited an up-regulation of basal and IFNγ-induced PD-L1 compared with PEO4 cells. PEO4 cells displayed a pronounced increase in the CCL5 and IFNγ-induced CXCL10 compared with PEO1 cells. Co-culture of PBMCs with PEO1 and PEO4 cells led to a significant decrease in activated CD8+ effector T and CD4+ helper T cells. However, co-culture of PBMCs with PEO4 cells caused a significant increase in activated CD4+ helper T cells. Co-culture of PBMCs with PEO4 cells caused a significant increase in FOXP3+CD4+CD25+ Tregs. This increase in Tregs was significantly reduced by the treatment with the CCL5/CCR5 antagonist TAK-779 or the CXCL10/CXCR3 antagonist AMG-487. Silencing of CCL5 or CXCL10 in PEO4 cells by siRNA significantly increased IFNγ production by SUPT1 cells and PBMCs. Conclusions: PEO4 cells secrete CCL5 and IFNγ-induced CXCL10 to activate Tregs, enabling tumor cells to evade host immune response by dysregulating their microenvironment. PEO4 cells-induced Tregs are reduced by CCL5/CXCL10 signaling blockade with TAG-779 or AMG-487. Furthermore, silencing of CCL5 or CXCL10 in PEO4 cells with siRNA abolishes Treg-mediated immunosuppression and restores the antitumor activity of effector T cells. Citation Format: Annabelle C. Lin, Jake Moscarelli, Z. Ping Lin, Elena S. Ratner. Blockade of CCL5 and CXCL10 signaling as a novel immunotherapy for epithelial ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 100.

Long non-coding RNAFOXD1-AS1 modulated CTCs epithelial-mesenchymal transition and immune escape in hepatocellular carcinoma in vitro by sponging miR-615-3p.

Hepatocellular carcinoma (HCC) is widely recognized as a globally prevalent malignancy. Immunotherapy is a promising therapy for HCC patients. Increasing evidence suggests that lncRNAs are involved in HCC progression and immunotherapy. The study reveals the mechanistic role of long non-coding RNA (lncRNA) FOXD1-AS1 in regulating migration, invasion, circulating tumor cells (CTCs), epithelial-mesenchymal transition (EMT), and immune escape in HCC in vitro. This study employed real-time PCR (RT-qPCR) to measure FOXD1-AS1, miR-615-3p, and programmed death-ligand 1 (PD-L1). The interactions of FOXD1-AS1, miR-615-3p, and PD-L1 were validated via dual-luciferase reporter gene and ribonucleoprotein immunoprecipitation (RIP) assay. In vivo experimentation involves BALB/c mice and BALB/c nude mice to investigate the impact of HCC metastasis. The upregulation of lncRNA FOXD1-AS1 in malignant tissues significantly correlates with poor prognosis. The investigation was implemented on the impact of lncRNA FOXD1-AS1 on the migratory, invasive, and EMT of HCC cells. It has been observed that the lncRNA FOXD1-AS1 significantly influences the generation and metastasis of MCTC in vivo analysis. In mechanistic analysis, lncRNA FOXD1-AS1 enhanced immune escape in HCC via upregulation of PD-L1, which acted as a ceRNA by sequestering miR-615-3p. Additionally, lncRNA FOXD1-AS1 was found to modulate the EMT of CTCs through the activation of the PI3K/AKT pathway. This study presents compelling evidence supporting the role of lncRNA FOXD1-AS1 as a miRNA sponge that sequesters miR-655-3p and protects PD-L1 from suppression.

Upregulation of PD-L1, VISTA, and CTLA-4 Gene Expression in a Melanoma Cell Line Following Chemotherapy: An In Vitro Study

Background: Melanoma, an aggressive form of skin cancer, has garnered substantial research attention due to its rising incidence and limited treatment efficacy. Tumor cells often become more aggressive post-chemotherapy, evading innate and adaptive immune responses, leading to recurrence and metastasis. Identifying mechanisms of chemotherapy resistance is crucial to reduce mortality rates. Negative immune pathways such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed death-ligand 1 (PD-L1), and V-domain Ig suppressor of T cell activation (VISTA) hinder immune responses to cancer. This study aimed to uncover the dynamic alterations in the expression patterns of key immune checkpoints VISTA, PD-L1, and CTLA-4 in melanoma cancer cell line. Methods: In this study, the A-375 melanoma cancer cell line was cultivated using conventional cell culture techniques. The IC50 (half-maximal inhibitory concentration) and efficacy assessment of chemotherapy drugs, docetaxel and doxorubicin, were determined using the MTT test. After treatment, an analysis of the expression of PD-L1, CTLA-4, and VISTA genes in the A-375 cell line was performed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). One-way analysis of variance (ANOVA) was used for statistical analysis. All experiments were conducted in triplicate, with significance set at P<0.05. Statistical significance is denoted as follows: *P<0.05, **P<0.01, ***P<0.001, and ****P<0.0001. Results: Significant upregulation of VISTA expression was observed in both ADO and ADC groups. CTLA-4 expression increased significantly in the ADC group, while no significant change was observed in the ADO group. PD-L1 expression was significantly higher in both ADO and ADC groups compared to the control group. Conclusion: These compelling findings underscore the profound impact of chemotherapeutic agents on the heightened expression of immune checkpoint genes, shedding light on the potential modulation of crucial pathways associated with immune response regulation.

The role of programmed death receptor (PD-)1/PD-ligand (L)1 in periodontitis and cancer.

The programmed-death-ligand-1 (PD-L1) is an immune-modulating molecule that is constitutively expressed on various immune cells, different epithelial cells and a multitude of cancer cells. It is a costimulatory molecule that may impair T-cell mediated immune response. Ligation to the programmed-death-receptor (PD)-1, on activated T-cells and further triggering of the related signaling pathways can induce T-cells apoptosis or anergy. The upregulation of PD-L1 in various cancer types, including oral squamous cell carcinomas, was demonstrated and has been linked to immune escape of tumors and poor prognosis. A bidirectional relationship exists between the increased PD-L1 expression and periodontitis as well as the epithelial-mesenchymal transition (EMT), a process of interconversion of epithelial cells to mesenchymal cells that may induce immune escape of tumors. Interaction between exosomal PD-L1 and PD-1 on T-cells may cause immunosuppression by blocking the activation and proliferation of T-cells. The efficacy and importance of treatment with PD-1/PD-L1 checkpoint inhibitors and their prognostic influence on human cancers was demonstrated. Regarding PD-1/PD-L1 checkpoint inhibitors, resistances exist or may develop, basing on various factors. Further investigations of the underlying mechanisms will help to overcome the therapeutic limitations that result from resistances and to develop new strategies for the treatment of cancer.

Hypoxia-induced PD-L1 expression and modulation of muscle stem cell allograft rejection.

Stem cell therapy has shown immense promise in treating genetic disorders, particularly muscular diseases like Duchenne muscular dystrophy (DMD). This study investigates a novel method to enhance the viability of stem cell transplants in DMD by upregulating Programmed Death Ligand 1 (PD-L1) in muscle stem cells (MuSCs) through preconditioning with hypoxia and/or interferon-γ (IFN-γ) to mitigate T cell immune rejection. MuSCs were treated with 5% hypoxia for 72h and further treated with IFN-γ to enhance PD-L1 expression. Additionally, gain and loss experiments using a PD-L1 inhibitor (BMS-1) were conducted to investigate cellular expression profiles in vitro and cell transplantation outcomes in vivo. Our results showed significant upregulation of PD-L1 in MuSCs under hypoxia and IFN-γ conditions without affecting cellular proliferation and differentiation in vitro. In vivo, these preconditioned MuSCs led to decreased infiltration of CD4+ and CD8+ T cells in implanted limb muscles of mouse models. Blocking PD-L1 reduced graft survival in muscles treated with MuSCs. Conversely, increased PD-L1 expression and reduced T cell infiltration correlated with improved graft survival, as identified by pre-labeled LacZ + MuSCs following transplantation. This study provides evidence that hypoxia and IFN-γ preconditioning of MuSCs can significantly enhance the efficacy of cell therapy for DMD by mitigating immune rejection. Our strategic approach aimed to improve donor cell survival and function post-transplantation by modifying immune responses towards the donor cells.

IL-10 dampens antitumor immunity and promotes liver metastasis via PD-L1 induction

The liver is one of the organs most commonly affected by metastasis. The presence of liver metastases has been reported to be responsible for an immunosuppressive microenvironment and diminished immunotherapy efficacy. Herein, we aimed to investigate the role of IL-10 in liver metastasis and to determine how its modulation could affect the efficacy of immunotherapy invivo. To induce spontaneous or forced liver metastasis in mice, murine cancer cells (MC38) or colon tumor organoids were injected into the cecum or the spleen, respectively. Mice with complete and cell type-specific deletion of IL-10 and IL-10 receptor alpha were used to identify the source and the target of IL-10 during metastasis formation. Programmed death ligand 1 (PD-L1)-deficient mice were used to test the role of this checkpoint. Flow cytometry was applied to characterize the regulation of PD-L1 by IL-10. We found that Il10-deficient mice and mice treated with IL-10 receptor alpha antibodies were protected against liver metastasis formation. Furthermore, by using IL-10 reporter mice, we demonstrated that Foxp3+ regulatory T cells (Tregs) were the major cellular source of IL-10 in liver metastatic sites. Accordingly, deletion of IL-10 in Tregs, but not in myeloid cells, led to reduced liver metastasis. Mechanistically, IL-10 acted on Tregs in an autocrine manner, thereby further amplifying IL-10 production. Furthermore, IL-10 acted on myeloid cells, i.e. monocytes, and induced the upregulation of the immune checkpoint protein PD-L1. Finally, the PD-L1/PD-1 axis attenuated CD8-dependent cytotoxicity against metastatic lesions. Treg-derived IL-10 upregulates PD-L1 expression in monocytes, which in turn reduces CD8+ T-cell infiltration and related antitumor immunity in the context of colorectal cancer-derived liver metastases. These findings provide the basis for future monitoring and targeting of IL-10 in colorectal cancer-derived liver metastases. Liver metastasis diminishes the effectiveness of immunotherapy and increases the mortality rate in patients with colorectal cancer. We investigated the role of IL-10 in liver metastasis formation and assessed its impact on the effectiveness of immunotherapy. Our data show that IL-10 is a pro-metastatic factor involved in liver metastasis formation and that it acts as a regulator of PD-L1. This provides the basis for future monitoring and targeting of IL-10 in colorectal cancer-derived liver metastasis.

Investigation of tryptophan to kynurenine degradation in response to interferon-γ in melanoma cell lines

Background and aimMelanoma is a fatal form of skin cancer that carries a grave prognosis if the cancer cells spread and form metastases. The Kynurenine (Kyn) pathway is activated by the enzyme indoleamine 2,3-dioxygenase 1 (IDO-1) and has been shown to have a role in tumour progression. We have previously shown that interferon-γ (IFN-γ) acts as an inducer of tryptophan (Trp) degradation to Kyn in keratinocytes of the basal layer in a 3D epidermis model. Before extending our reconstructed human epidermis model to not only contain keratinocytes but also fibroblasts and melanocytes/melanoma cells, we have in this study set out to investigate possible differences between primary adult melanocytes and six melanoma cell lines regarding the expression of the immune checkpoint inhibitors IDO-1 and programmed death ligand 1 (PD-L1) together with Kyn production. MethodsThe melanocytes and melanoma cells were stimulated with 1–20 ng/ml of IFN-γ and the levels of Trp to Kyn degradation were monitored with high-performance liquid chromatography (HPLC). To analyze the viability of the cell types after IFN-γ treatment, an MTT assay was performed. mRNA quantity of IDO-1, PD-L1 and IFN-γ receptor (IFN-GR1) was analyzed with qPCR. ResultsAfter 24 h, only the metastatic cell line WM-266-4 was affected by all concentrations of IFN-γ, whereas at 48 h, the higher IFN-γ concentrations gave a more pronounced effect on the viability in all cell types. Trp was detected at various levels in the culture medium from all cell types before and after IFN-γ treatment. The degradation to Kyn was detected in primary melanocytes, Mel Juso, and Mel Ho cell lines after 24 h of treatment and low levels of IFN-γ. However, the higher concentration of IFN-γ, 20 ng/ml, induced Kyn to various degrees in all cell types after 24 h. The change in mRNA quantity of IDO-1 and PD-L1 was similar in all cell types. ConclusionTo conclude, no significant difference in upregulation of the immune checkpoint inhibitors PD-L1 and IDO-1 was seen between primary tumour and metastatic melanoma. IFN-γ stimulation of melanocytes and different stages of melanoma cell lines resulted in an increased Kyn/Trp ratio in the more aggressive melanoma cells when a high concentration was used (20 ng/ml) but when a lower concentration of IFN-γ (5 ng/ml) was used an increased Kyn/Trp ratio were detected in media from primary melanocytes and early-stage melanoma.