29126

CD274

Immunosuppression of tumour-infiltrating lymphocytes (TIL) is a common feature of advanced cancer, but its biological basis has remained obscure. We demonstrate here a molecular link between epithelial-to-mesenchymal transition (EMT) and CD8(+) TIL immunosuppression, two key drivers of cancer progression. We show that microRNA-200 (miR-200), a cell-autonomous suppressor of EMT and metastasis, targets PD-L1. Moreover, ZEB1, an EMT activator and transcriptional repressor of miR-200, relieves miR-200 repression of PD-L1 on tumour cells, leading to CD8(+) T-cell immunosuppression and metastasis. These findings are supported by robust correlations between the EMT score, miR-200 levels and PD-L1 expression in multiple human lung cancer datasets. In addition to revealing a link between EMT and T-cell dysfunction, these findings also show that ZEB1 promotes metastasis through a heretofore unappreciated cell non-autonomous mechanism, and suggest that subgroups of patients in whom malignant progression is driven by EMT activators may respond to treatment with PD-L1 antagonists.

The incidence of kidney cancer has been increasing globally during the past two decades. Renal cell carcinoma (RCC) is the most aggressive subtype of kidney cancer, which usually deteriorates with epithelial-mesenchymal transition (EMT) that facilitates the migration and invasion of cancer cells. Till now, the underlying mechanism remains unclear. In this study, we demonstrated that programmed death ligand 1 (PD-L1/B7-H1/CD274) could induce EMT and enhance RCC cell cancer stemness through up-regulation of SREBP-1c. Furthermore, we found that PD-L1 is up-regulated in human RCC metastases. These results, taken together, provide evidence for a novel mechanism of PD-L1 in RCC progression, suggesting that there is a close relationship between EMT and immune escape signaling pathways in RCC.

Virus-associated malignancies and sarcomatoid cancers correlate with high PD-L1 expression, however, underlying mechanisms remain controversial. We evaluated the correlation between PD-L1 expression and epithelial-mesenchymal transition (EMT) in head and neck squamous cell carcinomas (HNSCC).tumor tissues from 50 patients with HNSCC were evaluated for PD-L1 by immunohistochemistry, which showed 32 (64.0%) were PD-L1 positive (PD-L1+). Interestingly, PD-L1 expression was significantly associated with EMT (P = 0.010), as assessed by low E-cadherin and high vimentin expression. The overall survival of PD-L1+ patients with EMT features was significantly worse than those without EMT features (P = 0.007). In an independent validation cohort (N = 91), as well as in HNSCC cases of The cancer Genome Atlas (TCGA) and the cancer Cell Line Encyclopedia, high PD-L1 expression was also associated with the high probability of an EMT signature, referred from the GEO dataset, GSE4824. Survival analysis confirmed PD-L1+/EMT+ patients had a poorer prognosis than PD-L1+/EMT- patients in the TCGA cohort. PD-L1 positivity can thus be divided into two categories according to the absence or presence of EMT. PD-L1 expression is also independently associated with EMT features in HNSCC.

BACKGROUND: Programmed cell death 1 (PD-1) negatively regulates antigen receptor signaling upon binding by either of its ligands, programmed cell death ligand 1 or 2 (PD-L1/2). Blockade of this interaction with either PD-1 or PD-L1 antibodies has been successful in the treatment of human cancer, especially melanoma and non-small cell lung cancer. PD-L1 expression has been proposed as a predictor of tumor response. However, the relationships between PD-L1 expression and various clinicopathological characteristics remain unclear. MATERIALS AND METHODS: PD-L1 expression was examined in 220 non-small cell lung cancer specimens that were consecutively resected at our hospital after validating the E1L3N antibody immunohistochemical assay by comparing IHC and RT-PCR data for lung cancer cell lines. We evaluated the relationships between PD-L1 positivity, several clinical factors and the immunohistochemical expression of epithelial-mesenchymal transition (EMT), cancer stem cell and proliferative markers. RESULTS: PD-L1 was expressed in 22% of lung adenocarcinomas and 60% of squamous cell lung cancers. There was no significant association between PD-L1 expression and clinicopathological features in squamous cell lung cancer. However, in patients with lung adenocarcinoma, PD-L1 expression was significantly correlated with solid subtype histology, vimentin expression, increased Ki-67 labeling index and poor prognosis by multivariate analysis. CONCLUSION: PD-L1 expression was associated with high proliferative activity and the EMT phenotype in adenocarcinoma but not in squamous cell carcinoma of the lung. PD-L1 expression was a significant poor prognostic factor in patients with lung adenocarcinoma.CI - Copyright (c) 2016 Elsevier Ireland Ltd. All rights reserved.

PD-1/PD-L1-targeted immunotherapy has emerged as a promising therapeutic strategy for pulmonary adenocarcinoma (pADC). epithelial-to-mesenchymal transition (EMT) is involved in the progression and immune evasion of cancers. Therefore, we investigated the association between PD-L1 expression and EMT phenotype in pADC. Immunohistochemistry for E-cadherin (epithelial marker), ZEB1, SNAIL, SLUG, vimentin (mesenchymal markers), PD-L1, CD8, and PD-1 was performed on 477 cases of pADC. Cases were classified into epithelial, mesenchymal, epithelial-mesenchymal, and unspecified types based on immunohistochemical results. PD-L1 expression was scored as 0 in 14.0% (n=67), 1 in 26.4% (n=126), 2 in 51.2% (n=244), and 3 in 8.4% (n=40). PD-L1 score was positively correlated with SNAIL and vimentin H scores (P<.001, both). After dichotomizing patients into PD-L1-negative and PD-L1-positive groups, PD-L1 positivity was significantly higher in patients with mesenchymal (71.2%; 84/118) and epithelial-mesenchymal (62.7%; 84/134) phenotypes compared with those with epithelial (50.6%; 44/87) and unspecified (50.0%; 35/70) phenotypes (P=.005). The significant association between PD-L1 expression and EMT phenotype was maintained in EGFR-mutated pADCs. Moreover, cases with EMT phenotype (ie, mesenchymal and epithelial-mesenchymal) were infiltrated by higher numbers of CD8(+) and PD-1(+) cells than those with epithelial and unspecified phenotypes in EGFR-mutated pADCs (P=.043 for CD8(+) cells and P<.001 for PD-l(+) cells). Particularly, cases with EMT phenotype and PD-L1 expression showed the greatest amount of CD8(+) and PD-1(+) cells in EGFR-mutated cases (P=.043 for CD8(+) cells and P=.005 for PD-1(+) cells). This study demonstrates that EMT phenotype is related to PD-L1 overexpression in pADC cells and patients with EMT-phenotype pADC may benefit from PD-1/PD-L1-blocking immunotherapy.CI - Copyright A(c) 2016 Elsevier Inc. All rights reserved.

Blockade of the programmed-death 1 receptor (PD-1)/programmed-death ligand (PD-L1) pathway efficiently reduces tumour growth and improves survival. Durable tumour regression with blockade of the PD-1/PD-L1 checkpoint has been demonstrated in recent clinical studies. Oral squamous cell carcinoma (OSCC) is highly immunosuppressive, and PD-L1 expression has been proposed as a potential mechanism responsible for this phenotype. Despite the fact that anti-PD-1 treatment can produce durable responses, such therapy appears to benefit only a subset of patients. Thus, it is important to understand the mechanisms underlying regulation of PD-L1 expression in the OSCC microenvironment. In this study, we showed that PD-L1 expression in high-grade invasive OSCC cell lines was lower than that in a low-grade invasive OSCC line and found a close correlation between PD-L1 expression and the epithelial-mesenchymal transition (EMT). PD-L1 expression was upregulated in macrophages and dendritic cells (DCs) in high-grade invasive human OSCC tissues or co-cultured with mesenchymal-phenotype OSCC cells in vitro. TLR4-inhibitory peptide successfully suppressed PD-L1 upregulation on macrophages and DCs co-cultured with mesenchymal-phenotype OSCC cells, suggesting that some EMT-induced tumour antigen is critical for PD-L1 induction on tumour-associated macrophages and DCs. Further studies are necessary to explore the impact of EMT on the tumour immune microenvironment and to identify potential biomarkers for selecting patients who might preferentially benefit from PD-1/PD-L1 blockade or immunotherapies more broadly.

Programmed death-ligand 1 (PD-L1) plays a crucial role in the host immune system in cancer progression. The gene promoter region of PD-L1 also contains a binding site for ZEB1, a transcription factor related to epithelial-mesenchymal transition (EMT). The purpose of this study was to clarify the relationship between PD-L1 and EMT and its clinical importance in esophageal squamous cell carcinoma (ESCC). PD-L1 and ZEB1 expression at the tumor invasive front was examined by immunohistochemistry in resected specimens from 90 patients with ESCC who underwent surgery without preoperative therapy, and their expression and clinicopathological factors were compared. ZEB1 and PD-L1 expression was determined in TE8 cells, which demonstrate the EMT phenotype, following ZEB1 knockdown by siZEB1. TE5, TE6 and TE11 cells with non-EMT phenotype were also used for studies of TGF-beta1-dependent EMT induction and ZEB1 and PD-L1 expression. In cases of high PD-L1 expression at the invasive front, significantly greater depth of tumor invasion, EMT, and less CD8(+) lymphocyte infiltration were observed. High PD-L1 expression was also associated with worse overall and relapse-free survival. A correlation was observed between PD-L1 and ZEB1 expression. In TE8 cells, siZEB1 suppressed PD-L1 and promoted E-cadherin mRNA and protein expression. TGF-beta1 induced EMT and surface expression of PD-L1 in TE5, TE6 and TE11 cell lines. PD-L1 expression at the ESCC invasive front was related to ZEB1 expression, EMT and poor prognosis. We suggest that a cooperative mechanism bridging between tumor immune avoidance and EMT contributes to tumor malignancy in ESCC.CI - (c) 2017 The Authors. cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese cancer Association.

BACKGROUND/AIMS: PD-L1 (Programmed cell death 1 ligand 1, PD-L1), an essential immune checkpoint molecule in the tumor microenvironment, is an important target for cancer immunotherapy. We have previously reported that its expression in human gastric and esophageal cancer tissues is significantly associated with cancer progression and patients' postoperative prognoses. Its expression in cancer cells is well known to inhibit the T cell-mediated anti-tumor response, and this mechanism of action has been targeted for cancer immunotherapy. As of now, the autonomous effect of PD-L1 on cancer cells is not well understood, thus our present study aimed to examine the role of PD-L1 intervention in cellular biological functions, especially epithelial to mesenchymal transition (EMT), of the human esophageal cancer cell line, Eca-109 cells. METHODS: Immunohistochemistry assay was used to investigate the correlation between expression of PD-L1 and EMT markers in human esophageal cancer tissues. Intervention of PD-L1 by using RNAi and over-expression methods were used to study the role of PD-L1 in regulation of biological behaviors and EMT in Eca-109 cells. RESULTS: Our clinical and pathological data demonstrated that tumor samples in the EMT positive subgroup had higher PD-L1 expression than those in the EMT negative subgroup. By manipulating PD-L1 expression in Eca-109 cells either through ablation or overexpression of wild type and the cytoplasmic domain-truncated mutant, we demonstrated that PD-L1 expression significantly promoted the cell viability, migration and EMT phenotype. Furthermore, our study also indicated that PD-1 fusion protein mediated stimulation of PD-L1 and the cytoplasmic domain of PD-L1 played a critical role in promoting EMT phenotype of Eca-109 cells, thereby suggesting that PD-1 receptor usually by triggering the reverse signaling can effect PD-L1 mediated regulation of esophageal cancer cell response. CONCLUSION: Our present study reveals a tumor cell-autonomous role of PD-L1 signaling in promoting EMT in human esophageal cancer.CI - (c) 2017 The Author(s). Published by S. Karger AG, Basel.

In cancer immunology, the programmed cell death 1-programmed cell death 1/ligand 1 (PD-1/PD-L1) pathway plays a major role. Anti-PD-1 and anti-PD-L1 antibodies provide reliable immunotherapy when given as treatment for various types of malignancy including lung cancer. PD-L1 expression in cancer cells has been reported to be a predictive factor for the therapeutic effects of immunotherapy. However, the mechanism of PD-L1 expression remains unclear. Another key process in cancer progression is epithelial-mesenchymal transition (EMT). In the present study, we investigated the mechanism of PD-L1 expression as well as changes in its expression during the EMT process in non-small cell lung cancer (NSCLC). In this study, A549 cells underwent EMT by treatment with TGF-beta or chemotherapeutic agents and then PD-L1 expression was evaluated. The alterations of PD-L1 expression was also examined during the reverse EMT process; mesenchymal-epithelial transition (MET). The relationship between for PD-L1 expression and EMT status in clinical specimens with NSCLC after induction chemotherapy were analyzed by immunohistochemical staining. We found that PD-L1 expression was upregulated following TGF-beta induction; in contrast, it was downregulated by TGF-beta receptor-kinase inhibitors and the MET process. Furthermore, chemo-treatment increased TGF-beta expression and enhances PD-L1 expression via autocrine TGF-beta induced EMT. Analysis of clinical samples revealed a significant relationship between PD-L1 expression and EMT status (P<0.05). In conclusion, our results suggest that PD-L1 expression is regulated by TGF-beta induced EMT and enhanced by chemo-treatment via the chemo-induced TGF-beta signaling. The anti-PD-1/PD-L1 blockade may provide more effective anticancer activities in combination with chemotherapy in NSCLC.

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor due to the lack of effective therapeutic drugs. cancer therapy targeting programmed cell death protein 1 (PD-1) or programmed death ligand-1 (PD-L1) is of revolutionary. However, the role of intrinsic PD-L1, which determines immune-therapy outcomes, remains largely unclear. Here we demonstrated an oncogenic role of PD-L1 via binding and activating Ras in GBM cells. RNA-sequencing transcriptome data revealed that PD-L1 significantly altered gene expression enriched in cell growth/migration/invasion pathways in human GBM cells. PD-L1 overexpression and knockout or knockdown demonstrated that PD-L1 promoted GBM cell proliferation and migration in vitro and in vivo. Mechanistically, PD-L1 prominently activated epithelial mesenchymal transition (EMT) process in a MEK/Erk- but not PI3K/Akt-dependent manner. Further, we identified intracellular interactions of PD-L1 and H-Ras, which led to Ras/Erk/EMT activation. Finally, we demonstrated that PD-L1 overexpression promoted while knockdown abolished GBM development and invasion in orthotopic GBM models of rodents. Taken together, we found that intracellular PD-L1 confers GBM cell malignancy and aggressiveness via binding Ras and activating the downstream Erk-EMT signaling. Thus, these results shed important insights in improving efficacy of immune therapy for GBM as well as other malignant tumors.CI - Copyright (c) 2018 Elsevier B.V. All rights reserved.

B7-H1 (CD274) is a T-cell coinhibitory molecule that is also often induced on human carcinoma cells, where its expression has been implicated in immune escape. Under inflammatory conditions, B7-H1 is also inducible in normal epithelial cells but little is known about its involvement in conversion of normal cells to tumor cells. Here, we show that skin-specific expression of B7-H1 accelerates inflammatory carcinogenesis in a methylcholantrene (MCA)-induced model of squamous cell carcinoma (SCC). Inflammatory responses induced by MCA or phorbol ester TPA were clearly inhibited in B7-H1 transgenic mice (B7-H1tg mice). Antibody-mediated blockade of either B7-H1 or the related molecule PD-1 revealed that their ability to limit inflammation relied on ligand interactions made by B7-H1 or PD-1. Skin keratinocytes derived from B7-H1tg mice exhibited constitutive reduction of E-cadherin, and SCC induced in B7-H1tg mice also showed loss of E-cadherin along with elevated expression of the transcription factors Slug and Twist that drive epithelial-mesenchymal transition (EMT). Our results indicate that upregulation of B7-H1 in skin epithelial cells promotes EMT and accelerates carcinogenesis, revealing insights into the significance of B7-H1 overexpression on solid tumor cells and hinting at a close relationship between EMT and immune escape signaling pathways in cancer.CI - (c)2010 AACR.