Upregulation Of Programmed Cell Death-ligand 1 Research Articles

GBP5 Repression Suppresses the Metastatic Potential and PD-L1 Expression in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype because of its high metastatic potential. Immune evasion due to aberrant expression of programmed cell death ligand 1 (PD-L1) has also been reported recently in metastatic TNBC. However, the mechanism underlying metastatic progression and PD-L1 upregulation in TNBC is still largely unknown. Here, we found that guanylate binding protein 5 (GBP5) is expressed in higher levels in TNBC tissues than in non-TNBC and normal mammary tissues and serves as a poorer prognostic marker in breast cancer patients. Transwell cultivation indicated that GBP5 expression is causally related to cellular migration ability in the detected TNBC cell lines. Moreover, the computational simulation of the gene set enrichment analysis (GSEA) program against the GBP5 signature generated from its coexpression with other somatic genes in TNBC revealed that GBP5 upregulation may be associated with the activation of interferon gamma (IFN-γ)-responsive and NF-κB-related signaling cascades. In addition, we found that the coexpression of GBP5 with PD-L1 was significantly positive correlation in TNBC tissues. Robustly, our data showed that GBP5 knockdown in TNBC cells harboring a higher GBP5 level dramatically suppresses the number of migrated cells, the activity of IFN-γ/STAT1 and TNF-α/NF-κB signaling axes, and the expression of PD-L1. Importantly, the signature combining a higher GBP5 and PD-L1 level predicted the shortest time interval of brain metastasis in breast cancer patients. These findings not only uncover the oncogenic function of GBP5 but also provide a new strategy to combat metastatic/immunosuppressive TNBC by targeting GBP5 activity.

Radiation induces epithelial to mesenchymal transition via upregulation of PD-L1 in nasopharyngeal carcinoma cell.

BackgroundThe acquisition of radioresistance by nasopharyngeal carcinoma (NPC) cells during radiotherapy may lead to tumor metastasis and poor survival. This study aimed to explore the mechanism of long-term radiation-induced NPC metastasis.MethodsThe radioresistant NPC cell, Hone-1R, was established for further study. A colony-forming assay was selected for the evaluation of radioresistant capacity, while a scratch wound healing assay was used to detect tumor cell migration. The expression of relative protein levels were detected by Western blot (WB) analysis and immunofluorescence. Cell morphology was acquired by microscopy. The programmed cell death ligand-1 (PD-L1) expression level in NPC tumor tissues was evaluated based on the publicly available datasets of NPC patients.ResultsA radioresistant NPC cell, Hone-1R, was established with a total dose of 180 Gy, and verified by radioresistant capacity testing. The morphology of Hone-1R cells showed obvious mesenchymal-like cells. WB and wound healing assays indicated that Hone-1R cells exhibited an epithelial-mesenchymal transition (EMT) phenotype with high migration ability and upregulation of PD-L1. Knockdown of PD-L1 reversed EMT status and reduced the migration ability of Hone-1R cells. Further analysis indicated that PD-L1 was overexpressed in more advanced stages and was positively correlated with the EMT score in NPC patients based on in silico analysis.ConclusionsOur study revealed that long-term radiation induces EMT and increases migration ability of NPC radioresistant cells through upregulation of PD-L1. These results advance our investigation of the underlying mechanism of ionizing radiation (IR)-induced migration, and suggest potential interventions to reverse EMT-induced acquisition of radioresistance in NPC.

Expression of peripheral monocytic programmed death ligand-1 in severe sepsis combined with HBV-related cirrhosis. A pilot observational study.

IntroductionHepatitis B virus (HBV)-related liver cirrhosis (LC) complicated with severe sepsis (SS) leads to HBV-related acute-on-chronic liver failure (HBV-ACLF). Programmed cell death ligand-1 (PD-L1)-associated immunosuppression is involved in both LC and SS. This study aimed to examine the expression and clinical relevance of PD-L1 on peripheral CD14+ monocytes in sepsis-induced HBV-ACLF.Material and methodsPD-L1 expression on peripheral CD14+ monocytes among the healthy control (HC), LC and LC + SS groups was examined using flow cytometry analysis and compared. In the LC + SS group, an SS-induced ACLF subgroup was identified. LC + SS patients were followed up for 28 days. The correlations between monocytic PD-L1 expression and illness severity scores and the prognostic value of monocytic PD-L1 expression in SS-induced HBV-ACLF patients was examined.ResultsThere were 17, 30 and 70 participants in the HC, LC and LC + SS groups, respectively. The monocytic PD-L1 expression was higher in the LC group compared with the HC group and in the LC + SS group compared with the LC group. The monocytic PD-L1 expression was positively correlated with the illness severity scores in LC + SS patients and predicted 28-day mortality of SS-induced HBV-ACLF patients (n = 59).ConclusionsSevere sepsis exhibits a superimposed effect of monocytic PD-L1 up-regulation on the basis of liver cirrhosis, and monocytic PD-L1 expression predicts 28-day mortality of SS-induced HBV-ACLF.

Blockade of AIM2 inflammasome or α1-AR ameliorates IL-1β release and macrophage-mediated immunosuppression induced by CAR-T treatment

BackgroundInterleukin (IL) 1 released from monocytes/macrophages is one of the critical determinants in mediating the adverse events of chimeric antigen receptor T cell (CAR-T) therapy, including cytokine release syndrome and...

The mechanism of ABL1 upregulating the expression of PD-L1 and the therapeutic effect of PD-L1 and STAT3 inhibitors in lung adenocarcinoma.

The upregulation of programmed cell death-ligand 1 (PD-L1) and continuous mutation of EGFR could induce chemoresistance in somatic cancers, however, the molecular mechanism of oncogene ABL1 in regulating the expression of PD-L1 in lung adenocarcinoma (LAD) remains unclear. In addition, the therapeutic effect of STAT3 and PD-L1 inhibitors in LAD is not fully understood. The ABL1 lentiviruses were used to transfect LAD cell lines (H1975, PC-9) with different EGFR mutation subtypes. Next, the expression of the JAK/STAT3 and PD-L1 pathway was detected followed by the treatment with STAT3 and PD-L1 inhibitors. Lastly, we observed the apoptosis and expression of STAT3 and PD-L1 before and after treatments in transfected and knocked down cell lines. The expression of ABL1 was upregulated by more than 3.71-fold and the expression of PD-L1 increased by 4.85-fold in lung cancer tissues compared with para-cancer tissues (both p<0.01), the ABL1 could induce upregulation of PD-L1 in LAD cell lines. Furthermore, the STAT3 inhibitor might induce more apoptosis than the PD-L1 inhibitor in both H1975 and PC-9 cell lines (both p<0.01) The STAT3 inhibitor combined with PD-L1 inhibitor had a synergistic effect on the PC-9 cell line, and the antagonistic effect was observed on the H1975 cell line. Furthermore, the expression of PD-L1 decreased almost equally after the PD-L1 inhibitor combined with a STAT3 inhibitor, or the STAT3 inhibitor alone (p>0.05). In addition, the STAT3 and PD-L1 decreased significantly after the STAT3 inhibitor compared with other treatments on the H1975 cell line (both p<0.01). To conclude, the EGFR mutation subtypes might influence the therapeutic efficacy in the treatment with PD-L1 inhibitor combined with STAT3 inhibitor on LAD cell lines.

Epithelial-to-mesenchymal transition and its association with PD-L1 and CD8 in thyroid cancer.

Programmed cell death-ligand 1 (PD-L1) has recently been shown to play a role in the regulation of epithelial-to-mesenchymal transition (EMT); however, the relationship between PD-L1 expression, EMT and the inflammatory tumour microenvironment has yet to be investigated in thyroid cancer. To address this issue, we examined the expression of CD8, PD-L1 and the EMT markers E-cadherin and vimentin in a cohort of 74 papillary thyroid cancer (PTC) patients and investigated the association of these with clinicopathologic characteristics and disease-free survival (DFS). The relationship between PD-L1 and EMT was further examined in three thyroid cancer cell lines via Western blot and live cell imaging. In order to expand our in vitro findings, the normalised gene expression profiles of 516 thyroid cancer patients were retrieved and analysed from The Cancer Genome Atlas (TCGA). PD-L1 positivity was significantly higher in PTC patients exhibiting a mesenchymal phenotype (P = 0.012). Kaplan–Meier analysis revealed that PD-L1 (P = 0.045), CD8 (P = 0.038) and EMT status (P = 0.038) were all significant predictors for DFS. Sub-analysis confirmed that the poorest DFS was evident in PD-L1 positive patients with EMT features and negative CD8 expression (P < 0.0001). IFN-γ treatment induced upregulation of PD-L1 and significantly promoted an EMT phenotype in two thyroid cancer cell lines. Our findings suggest that PD-L1 signalling may play a role in stimulating EMT in thyroid cancer. EMT, CD8 and PD-L1 expression may serve as valuable predictive biomarkers in patients with PTC.

PD-L1 expression in tongue squamous cell carcinoma.

Immune checkpoint proteins programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are important therapeutic targets for head and neck cancer. This large-scale case study aimed to analyze tongue squamous cell carcinomas (SCCs) and evaluate the correlation between PD-L1 expression and clinical prognosis. So far, this study is the largest case study on PD-L1 expression in tongue SCCs. This is a case-control study that analyzed 121 tongue SCCs. Paraffin-embedded sections and clinical data were obtained retrospectively and immunohistochemistry with PD-L1 was performed. 11.6% contained ≥ 50% of PD-L1-positive cells, 57.1% of these cases had a poor prognosis with nodal metastasis. Among cases of T1/2 primary lesions with nodal metastasis, cases of high PD-L1 expression had a significantly shorter disease-free survival than cases of no PD-L1 expression (p = 0.018). The hazard ratio for high PD-L1 expression was 3.21 (95 per cent CI, 1.26-8.72) compared with no PD-L1 expression after adjusting for other factors. These data indicate that PD-L1 upregulation in tongue SCCs is associated with a more advanced stage and shorter disease-free survival. PD-1/PD-L1 inhibitors might hence constitute potential adjuvant therapy for tongue SCCs with PD-L1 upregulation.

Daratumumab prevents programmed death ligand-1 expression on antigen-presenting cells in de novo multiple myeloma.

BackgroundDaratumumab (Dara), an anti‐CD38 monoclonal antibody, has an immunologic mechanism of action through targeting of CD38 expressing immune cells in patients with multiple myeloma (MM). Furthermore, it was recently shown that CD38 upregulation in tumors, is a major mechanism of acquired resistance to antiprogrammed cell death 1 (PD‐1)/programmed cell death ligand 1 (PD‐L1). Therefore, we decided to evaluate the immunomodulatory effects of CD38 blockade by Dara on the PD‐L1 expressing immune cells.MethodsWe analyzed CD38 and PD‐L1 expression on immune cells at different time points in 18 newly diagnosed MM receiving bortezomib, lenalidomide and dexamethasone, with or without Dara.ResultsWe first confirmed that CD38 is widely expressed on immune cells, with the strongest expression on plasmacytoid dendritic cells (pDC). Furthermore, Dara induces a strong depletion of pDC in addition to the well‐known rapid depletion of natural killer cells. Finally, we found that PD‐L1 expression on antigen‐presenting cells (APC) increases with MM treatment in patients that did not received Dara, while addition of Dara prevents this increase.ConclusionOverall, our results suggest new mechanisms of action of Dara through depletion of pDC and prevention of PD‐L1 upregulation expression on APC. Our finding provides new evidences for development of therapeutic strategies targeting both CD38 and PD‐L1/PD‐1 pathway in patients with MM.

PARP inhibition and immune modulation: scientific rationale and perspectives for the treatment of gynecologic cancers.

Poly[adenosine diphosphate (ADP) ribose]polymerase (PARP) has multifaceted roles in the maintenance of genomic integrity, deoxyribonucleic acid (DNA) repair and replication, and the maintenance of immune-system homeostasis. PARP inhibitors are an attractive oncologic therapy, causing direct cancer cell cytotoxicity by propagating DNA damage and indirectly, by various mechanisms of immunostimulation, including activation of the cGAS/STING pathway, paracrine stimulation of dendritic cells, increased T-cell infiltration, and upregulation of death-ligand receptors to increase susceptibility to natural-killer-cell killing. However, these immunostimulatory effects are counterbalanced by PARPi-mediated upregulation of programmed cell-death-ligand 1 (PD-L1), which leads to immunosuppression. Combining PARP inhibition with immune-checkpoint blockade seeks to exploit the immune stimulatory effects of PARP inhibition while negating the immunosuppressive effects of PD-L1 upregulation.

Tumor PD-L1 Induction by Resveratrol/Piceatannol May Function as a Search, Enhance, and Engage ("SEE") Signal to Facilitate the Elimination of "Cold, Non-Responsive" Low PD-L1-Expressing Tumors by PD-L1 Blockade.

Programmed cell death ligand 1 (PD-L1) is an immune regulatory protein that facilitates tumor escape from host immune surveillance. In the clinic, tumors with high level of PD-L1 have been used to identify patients who might respond favorably to treatment by anti-PD-L1 antibodies (PD-L1 blockade, PLB). Typically, a progression-free response of 9–20% to PLB has been observed, the basis for the low success rate is largely unknown. Recently, we show upregulation of PD-L1 in cancer cells by ≥IC50 supra-pharmacological dose of grape polyphenol resveratrol and piceatannol, alone and combined. Herein, we summarize recent published studies on the regulation of tumor PD-L1 by flavonoids and grape polyphenols. We hypothesize that the induced tumor PD-L1 by resveratrol and/or piceatannol may serve as a Search, Enhance, and Engage (“SEE”) signal to sensitize and augment the recognition and detection of low PD-L1-expressing “cold, non-responsive” tumors. The “SEE” strategy enhances the “visibility” of previously unidentified tumor cells for targeting and eventual eradication by the host antitumor activity. This strategy expands the selection criteria for patients with improved sensitivity and potential responsiveness when used in combination with PLB. The modulation of tumor PD-L1 by flavonoids or polyphenols is proposed to improve the response to PLB in low PD-L1 tumors.

P12.06 Clinicopathological evaluation of PD-L1 expression and cytotoxic T-lymphocyte infiltrates across intracranial molecular subgroups of ependymomas

Abstract BACKGROUND Immune check-point blockade targeting programmed cell death ligand-1 (PD-L1)/programmed death-1 (PD-1) axis has created paradigm shift in the treatment of advanced cancer. The prognosis of the ‘ST-RELA’ and ‘PF-A’ molecular subgroups of ependymomas (EPN) remains poor. This study aims to understand the potential candidature of EPNs for ICB. MATERIAL AND METHODS All supratentorial (ST) Grade II/III EPNs were classified into ST-RELA, ST-YAP and ST-not otherwise specified (NOS), based on L1CAM protein expression and/or presence of RELA/YAP1 fusion transcripts by RT-PCR. All posterior fossa (PF) BEPNs were classified into PF-A and PF-B based on H3K27me3 protein expression and chromosome 1q gain. Immunohistochemistry for PD-L1 (SP263, Ventana) and CD8 was performed. RelA protein enrichment at PDL1 promoter site was analysed by chromatin immunoprecipitation-qPCR (ChIP-qPCR) in three ST-RELA samples. RESULTS A total of 83 intracranial EPNs were included as follows: ST-RELA (n=32), ST-YAP (n=1), ST-NOS (n=11), ST-subependymoma (n=1), PF-A (n=25) and PF-B (n=13). Median tumor infiltrating CD8+ cytotoxic T-lymphocyte (CTL) density was 6/mm2, and was higher in ST EPNs (median 10/mm2) as compared to PF EPNs (median 3/mm2). PD-L1 protein expression in ≥1% tumor cells was noted in 17/83 (20%) of all EPNs, including 12/32 (37%) of ST-RELA and rare ST-NOS (2/11), PF-A (2/25) and PF-B (1/13) tumors. Twelve intracranial EPNs (14%, 12/83) showed high CTL density and concurrent PD-L1 positivity, of which majority (83%, 10/12) were ST-RELA EPNs. Enrichment of RelA protein was seen at PD-L1 promoter. CONCLUSION Increased CTL densities and upregulation of PD-L1 in ST-RELA ependymomas suggests potential candidature for immunotherapy.

Cisplatin contributes to programmed death-ligand 1 expression in bladder cancer through ERK1/2-AP-1 signaling pathway.

Bladder cancer (BC) is the second most common urologic malignancy and the ninth most common malignancy worldwide. Surgical resection is the mainstay of treatment for patients with early-stage disease, whereas therapeutic options are limited for patients with advanced-stage or residual BC. Programmed cell death ligand-1 (PD-L1) is an important target for immunotherapy. It is known that PD-L1 is overexpressed in BC; a clinical trial involving PD-L1 immune checkpoint inhibitors in advanced BC is ongoing. In the present study, we used Western blot and quantitative real-time PCR (qPCR) to define the expression level of PD-L1 after cisplatin treatment in BC-derived cell lines. The signal activation was also evaluated by Western blot in BC-derived cell lines. We found that chemotherapeutic drug cisplatin can induce PD-L1 but not PD-L2 expression in BC-derived cell lines. Furthermore, the expression level of PD-L1 was increased in a dose- and time-dependent manner after cisplatin treatment. The cisplatin-induced PD-L1 expression is mainly mediated by ERK1/2 but not Akt/mTOR signal pathway. Moreover, we found that cisplatin activates transcription factor activator protein-1 (AP-1) to regulate PD-L1 expression. The chemotherapy drug such as cisplatin may trigger resistance of BC through PD-L1 up-regulation. The present study suggests that PD-L1 antibody should be used concomitantly with chemotherapy in the setting of advanced and metastatic BC.

Clinicopathological evaluation of PD-L1 expression and cytotoxic T-lymphocyte infiltrates across intracranial molecular subgroups of ependymomas: are these tumors potential candidates for immune check-point blockade?

Immune check-point blockade (ICB) targeting programmed cell death ligand-1 (PD-L1)/programmed death-1 (PD-1) axis has created paradigm shift in cancer treatment. 'ST-RELA' and 'PF-A' molecular subgroups of ependymomas (EPN) show poor outcomes. We aimed to understand the potential candidature of EPNs for ICB. Supratentorial (ST) Grade II/III EPNs were classified into ST-RELA, ST-YAP, and ST-not otherwise specified (NOS), based on RELA/YAP1 fusion transcripts and/or L1CAM and p65 protein expression. Posterior fossa (PF) EPNs were classified into PF-A and PF-B based on H3K27me3 expression. Immunohistochemistry for PD-L1 and CD8 was performed. RelA protein enrichment at PDL1 promoter site was analysed by chromatin immunoprecipitation-qPCR (ChIP-qPCR). Eighty-three intracranial EPNs were studied. Median tumor infiltrating CD8 + cytotoxic T-lymphocyte (CTL) density was 6/mm2, and was higher in ST-EPNs (median 10/mm2) as compared to PF-EPNs (median 3/mm2). PD-L1 expression was noted in 17/83 (20%) EPNs, including 12/31 ST-RELA and rare ST-NOS (2/12), PF-A (2/25) and PF-B (1/13) EPNs. Twelve EPNs (14%) showed high CTL density and concurrent PD-L1 positivity, of which majority (10/12) were ST-RELA EPNs. Enrichment of RelA protein was seen at PDL1 promoter. Increased CTL densities and upregulation of PD-L1 in ST-RELA ependymomas suggests potential candidature for immunotherapy.

Abstract 2110: WEE1 inhibition could reverse trastuzumab resistance by downregulation of PD-L1 in HER2-positive cancers

Abstract Background: Trastuzumab in combination with chemotherapy is a standard of care for patients with HER2-positive breast and gastric cancer. Resistance mechanism to trastuzumab, anti-HER2 therapy, includes multiple pathways. Cancer cells could evade immune surveillance through high expression of programmed cell death ligand 1 (PD-L1) on cancer or immune cells. Among resistance mechanisms to trastuzumab, the role of PD-L1 modulation has not yet been discovered in HER2-positive cancers. WEE1 is involved in cell cycle progression and DNA damage response (DDR), and, interestingly, beyond DDR, it could modulate immunes. We aimed to evaluate the role of PD-L1 in trastuzumab resistance in HER2-positive cancers with/without immune cells and to explore WEE1 inhibitor as a trastuzumab resistance overcoming strategy by modulation of PD-L1. Methods: Four trastuzumab-resistant (HR) cells (SNU216HR, N87HR, SNU2670HR, SNU2773HR) were established from 2 HER2-amplified gastric cancer cells (SNU216, NCI-N87) and 2 HER2-amplified biliary tract cancer cells (SNU2670, SNU2773). For WEE1 inhibition, AZD1775 was used. MTT assay, colony formation assay, cell cycle analysis by FACS Calibur flow cytometer, and western blot were done. Results: All four HR cells showed PD-L1 upregulation compared with parental cells. When PD-L1 was knocked-down by transfection with si-PD-L1, anti-growth/proliferation effects were observed in MTT assay and colony forming assay. PD-L1 itself may promote cancer cell growth without interacting with immune cells. AZD1775 downregulated PD-L1 expression and induced cell cycle arrest at sub-G1 and G2/M phases in all 4 HR cells. The synergistic anti-proliferative effects were found in all 4 HR cells with co-treatment of trastuzumab and AZD1775. Conclusion: PD-L1 upregulation may contribute to trastuzumab resistance in HER2-positive cancer cells. Targeting WEE1-PD-L1 pathway might be a candidate strategy to overcome trastuzumab resistance in HER2-positive cancers. Citation Format: Meihua Jin, Ah-Rong Nam, Ji-Eun Park, Ju-Hee Bang, Kyoung-Seok Oh, Do-Youn Oh, Yung-Jue Bang. WEE1 inhibition could reverse trastuzumab resistance by downregulation of PD-L1 in HER2-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2110.

Expression of programmed cell death-ligand 1 in oral squamous cell carcinoma and oral leukoplakia is associated with disease progress and CD8+ tumor-infiltrating lymphocytes

ObjectiveIn recent years, monoclonal antibodies targeting programmed cell death-ligand 1 (PD-L1) have become a promising cancer immunotherapy. However, the role of PD-L1 in oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMDs), including oral leukoplakia (OLK), remains controversial. The aim of the present study was to investigate the expression level of PD-L1 in OSCC and OPMDs, and examine its relationship with CD8 expression and different clinicopathological features. MethodExpression of PD-L1 and CD8 were conducted in 41 OSCC, 21 OLK, and 25 normal mucosa samples by immunohistochemistry. Then, the density of PD-L1 expression was measured, and its correlation with CD8 expression and different clinicopathological features was analyzed. ResultsPD-L1 protein was detected in 97.6% of OSCC, 61.9% of OLK, and 0% of normal tissues. PD-L1 was highly expressed in human OSCC tissue (P < 0.0001), when compared to both OLK and control tissues. PD-L1 positivity was significantly associated with CD8 density (P < 0.0001, r = 0.8491). The PD-L1 high expression OSCC group displayed a trend for improved overall survival (OS) and disease-free survival (DFS) compared to the low expression group, although the differences were not significant. Moreover, the expression level of PD-L1 in OSCC was positively correlated with the pathological grade (P < 0.0001), but it was independent of age, gender, smoking, drinking, tumor size, lymph node status, or recurrence (P > 0.05). Also, there was a significant upregulation of PD-L1 expression observed in the OLK group compared to the control group (P < 0.0001). PD-L1 positivity in OLK patients was associated with gender and smoking habits (P < 0.05), but it did not correlate with age, drinking, or dysplasia (P > 0.05). ConclusionThe upregulation of PD-L1 may be associated with disease progress and CD8+ tumor-infiltrating lymphocytes in oral premalignant and malignant lesions.

MRNA expression of programmed cell death ligand 1 and components of the phosphatidylinositol 3-kinase/AKT/phosphatase and tensin homolog pathway in epidermal growth factor receptor mutation-positive lung adenocarcinoma.

The objective of this study is to investigate the relationship between programmed cell death ligand 1 (PD-L1) expression and the mutation status of epidermal growth factor receptor (EGFR) in lung adenocarcinoma, as well as the correlation between the clinical features of patients and mRNA levels of PD-L1 and components of the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT)/phosphatase and tensin homolog (PTEN) pathways. mRNA levels of PD-L1, PI3K, AKT, and PTEN in tumor and matched normal tissues of patients with EGFR mutation-positive lung adenocarcinoma were determined by real-time polymerase chain reaction. Twenty-three patients with EGFR mutation-positive lung adenocarcinoma were enrolled, and 46 samples (23 pairs of tumor and matched normal lung tissues) were collected. PD-L1 and AKT mRNA levels were higher in EGFR mutation-positive lung adenocarcinoma than in matched normal lung tissues (P = 0.047 and P = 0.046, respectively), whereas PI3K and PTEN mRNA levels were significantly lower in the cancerous tissues (P = 0.009 and P = 0.039, respectively). PD-L1 expression was positively correlated with PI3K/AKT signaling pathway activation. PD-L1 upregulation in lung adenocarcinoma was positively correlated with EGFR exon 19 mutations (P = 0.034). AKT mRNA upregulation was correlated with lymph node metastasis (P = 0.034). PTEN mRNA downregulation was correlated with high tumor staging and lymph node metastasis (P = 0.035 and P = 0.014, respectively). Elevated PD-L1 mRNA expression in lung adenocarcinoma is associated with EGFR mutation and may be mediated through the PI3K-AKT pathway. EGFR exon 19 mutations closely correlate with increased PD-L1 mRNA expression. Increased AKT mRNA expression correlates with lymph node metastasis, while decreased PTEN mRNA levels correlate with advanced tumor stage and lymph node metastasis.

Type 1 IFN and PD-L1 Coordinate Lymphatic Endothelial Cell Expansion and Contraction during an Inflammatory Immune Response.

Lymph node (LN) expansion during an immune response is a complex process that involves the relaxation of the fibroblastic network, germinal center formation, and lymphatic vessel growth. These processes require the stromal cell network of the LN to act deliberately to accommodate the influx of immune cells to the LN. The molecular drivers of these processes are not well understood. Therefore, we asked whether the immediate cytokines type 1 IFN produced during viral infection influence the lymphatic network of the LN in mice. We found that following an IFN-inducing stimulus such as viral infection or polyI:C, programmed cell death ligand 1 (PD-L1) expression is dynamically upregulated on lymphatic endothelial cells (LECs). We found that reception of type 1 IFN by LECs is important for the upregulation of PD-L1 of mouse and human LECs and the inhibition of LEC expansion in the LN. Expression of PD-L1 by LECs is also important for the regulation of LN expansion and contraction after an IFN-inducing stimulus. We demonstrate a direct role for both type 1 IFN and PD-L1 in inhibiting LEC division and in promoting LEC survival. Together, these data reveal a novel mechanism for the coordination of type 1 IFN and PD-L1 in manipulating LEC expansion and survival during an inflammatory immune response.

Intratumoral Delivery of an Adenoviral Vector Carrying the SOCS-1 Gene Enhances T-Cell-Mediated Antitumor Immunity By Suppressing PD-L1.

Ovarian cancer is the leading cause of gynecologic cancer-related deaths and novel therapeutic strategies are required. Programmed cell death 1 and programmed cell death ligand 1 (PD-L1), which are key mediators of host immune tolerance, are associated with ovarian cancer progression. Recent evidence indicates the importance of IFNγ-induced PD-L1 for immune tolerance in ovarian cancer. This study aimed to reveal the therapeutic potential of suppressor of cytokine signaling 1 (SOCS-1), an endogenous inhibitor of the Janus kinase (JAK)-STAT signaling pathway, for the treatment of ovarian cancer. IHC assessment revealed that patients with ovarian cancer with high intratumoral STAT1 activation exhibited poor prognosis compared with patients with low STAT1 activation (P < 0.05). Stimulation of OVISE, OVTOKO, OV2944-HM-1 (HM-1), and CT26 cell lines with IFNγ induced STAT1 phosphorylation and PD-L1 expression. Adenovirus-mediated SOCS-1 gene delivery (AdSOCS-1) in HM-1 and CT26 cells in vitro potently inhibited IFNγ-induced STAT1 phosphorylation and PD-L1 upregulation, similar to the addition of JAK inhibitor I, but failed to inhibit their proliferation. Notably, intratumoral injection of AdSOCS-1, but not AdLacZ, significantly inhibited the tumor growth of HM-1 and CT26 cells subcutaneously transplanted in immunocompetent syngeneic mice. AdSOCS-1 reduced PD-L1 expression on tumors and restored the activation of tumor-infiltrating CD8+ T cells. Moreover, the antitumor effect of AdSOCS-1 was significantly attenuated by PD-L1 Fc-fusion protein administration in vivo, suggesting that the effect of AdSOCS-1 is mainly attributable to enhancement of tumor immunity. This study highlights the potential clinical utility of SOCS-1 as an immune checkpoint inhibitor. Mol Cancer Ther; 17(9); 1941-50. ©2018 AACR.

Effect of anthracycline and taxane on the expression of programmed cell death ligand-1 and galectin-9 in triple-negative breast cancer

This study identified chemotherapeutic agents that up-regulate programmed cell death ligand-1 (PD-L1) and galectin-9 (Gal-9) in breast cancer cells. Immunohistochemical (IHC) staining was used to evaluate changes in PD-L1 and Gal-9 expression in the tumor tissue of triple-negative breast cancer (TNBC) patients who received anthracycline- and taxane-based neoadjuvant chemotherapy. To determine whether PD-L1 and Gal-9 expression changes were attributable directly to chemotherapeutics, MDA-MB-231 cells and HS578T cells were treated with different concentrations of anthracycline and taxane. Expression levels of PD-L1 and Gal-9 were evaluated and the activation status of NFκB in MDA-MB-231 and HS578T cells was determined to identify the PD-L1 and Gal-9 up-regulation mechanism. Three cases of increased PD-L1 expression and two of increased Gal-9 expression were observed among the TNBC patients. PD-L1 and Gal-9 expression were up-regulated by anthracycline and taxane in MDA-MB-231 cells, but not in HS578T cells. Increased nuclear levels of NFκB were observed in MDA-MB-231 cells treated with 0.5 μM epirubicin. Anthracycline and taxane up-regulated PD-L1 and Gal-9 expression in some subtypes of TNBC. This study provides useful reference data for clinical trials investigating combination treatments with immune checkpoint inhibitors and chemotherapy.

Abstract 3625: MET signaling upregulates PD-L1 expression in human lung and gastric cancer

Abstract Background: Tyrosine kinase receptor, MET, plays an important role for the progression of tumor through diverse mechanisms. Cancer immunotherapy targeting PD-1/PD-L1 pathway shows clinical benefit in patient with PD-L1 expressing solid tumor. In our previous study on non-small cell lung cancer (NSCLC) using immunohistochemistry, MET overexpression was significantly associated with programmed cell death-ligand 1 (PD-L1) overexpression. Thus, we investigated if MET signaling pathway is involved in PD-L1 expression in tumor cells. Method and Result: Lung adenocarcinoma cell lines including H596 (harboring MET exon 14 skipping mutation), H1993 (harboring MET gene amplification), H23 and H522 (MET wild-type), and a gastric carcinoma cell line, Hs746T (harboring MET exon 14 skipping mutation and gene amplification) were used. Hs746T cells were treated with MET inhibitor or transfected with MET siRNA and subject to microarray analysis. MET inhibition or knockdown led to changes in expression level of variable immune-related molecules, of which PD-L1 was one of the most down-regulated molecules. Stimulation of H596, H23 and H522 cells with HGF, a MET ligand, increased PD-L1 expression at the mRNA and protein level. Treatment of H1993 and Hs746T cells with MET inhibitor or MET knockdown using siRNA resulted in down-regulation of PD-L1 at the mRNA, total protein, and surface expression levels. PI3K/Akt and MAPK/Erk signaling pathways were involved in MET-mediated PD-L1 up-regulation in H1993 and Hs746T cells. Finally, the Cancer Genome Atlas (TCGA) analysis showed that MET and PD-L1 expression are significantly positively correlates with each other in patients with lung cancer (in NSCLC, rho=0.219 [p&amp;lt;0.001]; in adenocarcinoma, r=0.401 [p&amp;lt;0.001]; in squamous cell carcinoma, r=0.144 [p=0.001]) and in patients with gastric cancer (r=0.137 [p=0.005]). Conclusion: This study demonstrates that MET signaling increases PD-L1 transcription and protein overexpression in lung and gastric cancer cells, which might contribute to immune escape of tumor via PD-1/PD-L1 pathway. MET-targeted therapy may be considered as combination therapy with PD-1/PD-L1 blockades. Citation Format: Hyunkyung Ahn, Sehui Kim, Ji Young Jang, Dohee Kwon, Jaemoon Koh, Young A Kim, Doo Hyung Chung, Yoon Kyung Jeon. MET signaling upregulates PD-L1 expression in human lung and gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3625.