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Multi-layered control of PD-L1 expression in Epstein-Barr virus-associated gastric cancer.

ABSTRACT: Gastric cancer (GC) is the fifth most common cancer worldwide. In approximately 10% of GC cases, cancer cells show ubiquitous and monoclonal Epstein-Barr virus (EBV) infection. A significant feature of EBV-associated GC (EBVaGC) is high lymphocytic infiltration and high expression of immune checkpoint proteins, including programmed death-ligand 1 (PD-L1). This highlights EBVaGC as a strong candidate for immune checkpoint blockade therapy. Indeed, several recent studies have shown that EBV positivity in GC correlates with positive response to programmed cell death protein 1 (PD-1)/PD-L1 blockade therapy. Understanding the mechanisms that control PD-L1 expression in EBVaGC can indicate new predictive biomarkers for immunotherapy, as well as therapeutic targets for combination therapy. Various mechanisms have been implicated in PD-L1 expression regulation, including structural variations, post-transcriptional control, oncogenic activation of intrinsic signaling pathways, and increased sensitivity to extrinsic signals. This review provides the most recent updates on the multilayered control of PD-L1 expression in EBVaGC.

SUBMITTER: Miliotis CN

PROVIDER: S-EPMC8244904 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Multi-layered control of PD-L1 expression in Epstein-Barr virus-associated gastric cancer.

Miliotis Christos N CN Slack Frank J FJ

Journal of cancer metastasis and treatment 20200523 13

Gastric cancer (GC) is the fifth most common cancer worldwide. In approximately 10% of GC cases, cancer cells show ubiquitous and monoclonal Epstein-Barr virus (EBV) infection. A significant feature of EBV-associated GC (EBVaGC) is high lymphocytic infiltration and high expression of immune checkpoint proteins, including programmed death-ligand 1 (PD-L1). This highlights EBVaGC as a strong candidate for immune checkpoint blockade therapy. Indeed, several recent studies have shown that EBV positi ...[more]

PMID: 34212113

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Project description:PurposeCausative factors of breast cancer include infections, such as Epstein-Barr virus (EBV) infection. The aim of this study was to analyze the clinicopathological features of EBV-positive (IBC) and determine if EBV affects programmed cell death receptor 1 (PD-1)/PD ligand 1 (PD-L1) expression in IBC, similar to other EBV-infected tumors with PD-L1/PD-1 expression.MethodsWe collected 140 samples of IBC tissues and 25 samples of adjacent tissues. All patients were followed-up by telephone from the day of surgery to December 2020. Chromogenic in-situ hybridization was performed to evaluate EBV-encoded RNA (EBER). Immunohistochemistry was performed to evaluate PD-L1 and PD-1 expressions. The correlation between PD1/PDL1 expression and clinicopathological features was also analyzed.ResultsEBER was detected in 57 of 140 (40.7%) IBC tissues and not detected in any adjacent tissue (P < 0.05). Clinicopathologic features of patients were consistent with EBV-associated IBC. EBV infection was correlated with the mass size, menopausal status, axillary lymph node metastasis, vascular invasion, Ki-67 index, clinical stage, and estrogen receptor and progesterone receptor expressions (all P < 0.05), but not with the histological type, invasive ductal carcinoma histological grade, or human epidermal growth factor receptor 2 (HER2) expression (all P > 0.05). The positive rate of PD-1/PD-L1 expression was higher in the EBV-positive group than in the EBV-negative group (P < 0.05). The Kaplan-Meier univariate survival analysis showed that EBV was associated with poor disease-free survival and overall survival in patients with IBC. PD-L1/PD-1 expression could predict a poor prognosis.ConclusionsIn this study, clinicopathologic characteristics of patients were consistent with EBV-infected IBC. Patients with EBV-positive breast cancer were more likely to have elevated PD-1/PDL-1 expression compared to those with EBV-negative breast cancer. This finding could serve as a basis to explore therapeutic targets, particularly immunotherapy, for patients with IBC.

Project description:BackgroundThe prognostic potential of PD-L1 is currently unclear in gastric carcinomas, although the immune checkpoint PD-1/PD-L1 inhibitors have produced promising results in clinical trials.MethodsWe explored the prognostic implications of programmed death ligand 1 (PD-L1) in 514 consecutive surgically-resected gastric carcinomas. Overall survival and recurrence-free survival were evaluated. Immunohistochemistry for PD-L1, CD8, FOXP3, and PD-1, and molecular grouping by in situ hybridization for Epstein-Barr virus (EBV)-encoded small RNAs and multiplex PCR for microsatellite instability (MSI) markers were performed. Additionally, to explore the function inherent to PD-L1, PD-L1-specific siRNA transfection, cell proliferation, invasion, migration and apoptosis assays were conducted in five gastric carcinoma cell lines.ResultsPD-L1(+) tumor and immune cells were observed in 101 (20%) and 244 patients (47%), respectively. "Tumoral PD-L1(+)/immune cell PD-L1(-)/CD8+/low tumor-infiltrating lymphocytes (TILs)," and more advanced-stage tumors were associated with unfavorable clinical outcomes in the entire cohort through multivariate analysis. Furthermore, tumoral PD-L1(+)/FOXP3+/low TILs were associated with worse clinical outcomes in EBV-positive and MSI-high carcinomas. Tumoral PD-L1(+) alone was an adverse prognostic factor in EBV-positive carcinomas, but not in MSI-high carcinomas, whereas PD-L1(+) immune cells or FOXP3+/high TILs alone were correlated with a favorable prognosis. PD-L1 knockdown in gastric carcinoma cells suppressed cell proliferation, invasion and migration, and increased apoptosis, which were all statistically significant in two EBV(+) cell lines, but not all in three EBV(-) cell lines.ConclusionsThe prognostic impact of PD-L1 may depend on the tumor microenvironment, and statuses of EBV and MSI, although PD-L1 innately promotes cancer cell survival in cell-based assays. The combination of "tumoral PD-L1/immune cell PD-L1/CD8+ TILs" may serve as an independent prognostic factor. Tumoral PD-L1(+)/immune cell PD-L1(-)/CD8+/low TILs showing a worse prognosis may be beneficial for combinatorial therapies of anti-PD-L1/PD-1 and anti-cytotoxic T-lymphocyte associated antigen 4 (CTLA4) that would promote effector T cells, thus attack the tumor.

Dataset Information

Multi-layered control of PD-L1 expression in Epstein-Barr virus-associated gastric cancer.

Publications

Multi-layered control of PD-L1 expression in Epstein-Barr virus-associated gastric cancer.

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