PD-L1 promotes tumor growth and progression by activating WIP and β-catenin signaling pathways and predicts poor prognosis in lung cancer

PD-L1 regulates cell proliferation and apoptosis in acute myeloid leukemia by activating PI3K-AKT signaling pathway

As immune checkpoint inhibitors (ICIs) continue to advance, more evidence has emerged that anti-PD-1/PD-L1 immunotherapy is an effective treatment against cancers. Known as the programmed death ligand-1 (PD-L1), this co-inhibitory ligand contributes to T cell exhaustion by interacting with programmed death-1 (PD-1) receptor. However, cancer-intrinsic signaling pathways of the PD-L1 molecule are not well elucidated. Therefore, the present study aimed to evaluate the regulatory network of PD-L1 and lay the basis of successful use of anti-PD-L1 immunotherapy in acute myeloid leukemia (AML). Data for AML patients were extracted from TCGA and GTEx databases. The downstream signaling pathways of PD-L1 were identified via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The key PD-L1 related genes were selected by weighted gene co-expression network analysis (WGCNA), MCC algorithm and Molecular Complex Detection (MCODE). The CCK-8 assay was used to assess cell proliferation. Flow cytometry was used to determine cell apoptosis and cell cycle. Western blotting was used to identify the expression of the PI3K-AKT signaling pathway. PD-L1 was shown to be elevated in AML patients when compared with the control group, and high PD-L1 expression was associated with poor overall survival rate. The ECM-receptor interaction, as well as the PI3K-AKT signaling pathway, were important PD-L1 downstream pathways. All three analyses found eight genes (ITGA2B, ITGB3, COL6A5, COL6A6, PF4, NMU, AGTR1, F2RL3) to be significantly associated with PD-L1. Knockdown of PD-L1 inhibited AML cell proliferation, induced cell apoptosis and G2/M cell cycle arrest. Importantly, PD-L1 knockdown reduced the expression of PI3K and p-AKT, but PD-L1 overexpression increased their expression. The current study elucidates the main regulatory network and downstream targets of PD-L1 in AML, assisting in the understanding of the underlying mechanism of anti-PD-1/PD-L1 immunotherapy and paving the way for clinical application of ICIs in AML.

Activation of Host-NLRP3 Inflammasome in Myeloid Cells Dictates Response to Anti-PD-1 Therapy in Metastatic Breast Cancers

Tumor-associated inflammation leads to dysregulated cytokine production that promotes tumor immune evasion and anti-tumor immunity dysfunction. In advanced stage breast cancer, the proinflammatory cytokine IL-1β is overexpressed due to large proportions of activated myeloid cells in the tumor microenvironment (TME). Here, we demonstrate the role of the host nucleotide-binding domain, leucine-rich containing family, pyrin domain-containing 3 (NLRP3) inflammasome in metastatic breast cancer. In vitro, we show that stimulation of THP-1 cells with conditioned media collected from MDA-MB-468 cells induced NLRP3 activation and increased Pdcd1l1 expression. In vivo, mice deficient in NLRP3 orthotopically implanted with metastatic breast cancer cell line (E0771) showed significant reduction in tumor growth (p < 0.05) and increased survival (p < 0.01). Inhibition of NLRP3 with the small molecule OLT1177® reduced expression of Pdcd1l1 (p < 0.001), Casp1 (p < 0.01) and Il1b (p < 0.01) in primary tumors. Furthermore, tumor-bearing mice receiving OLT1177® showed reduced infiltration of myeloid-derived suppressor cells (MDSCs) (p < 0.001) and increased CD8+ T cells (p < 0.05) and NK cells (p < 0.05) in the TME. NLRP3 inhibition in addition to anti-PD-1 treatment significantly reduced tumor growth from the monotherapies (p < 0.05). These data define NLRP3 activation as a key driver of immune suppression in metastatic breast cancers. Furthermore, this study suggests NLRP3 as a valid target to increase efficacy of immunotherapy with checkpoint inhibitor in metastatic breast cancers.

An unexpected role for PD-L1 in front-rear polarization and directional migration

Programmed cell death-ligand 1 (PD-L1)-mediated T cell inhibition through PD-1 is a key checkpoint frequently exploited by tumors to evade immunity. In this issue, Wang et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202108083) reveal an unexpected role for PD-L1 in promoting tumor cell front-rear polarity and directionally persistent cell migration, independently of PD-1.

Glucose-Restricted Diet Regulates the Tumor Immune Microenvironment and Prevents Tumor Growth in Lung Adenocarcinoma

Background

Lung cancer is the second common cancer type in western countries and has a high mortality. During the development and progression of the tumor, the nutrients in its environment play a central role. The tumor cells depend crucially on glucose metabolism and uptake. Tumor cell metabolism is dominated by the Warburg effect, where tumor cells produce large amounts of lactate from pyruvate under aerobic conditions. We thus reasoned that, reducing carbohydrates in the diet might support anti-tumoral effects of current immunotherapy and additionally target tumor immune escape.

Objectives

The link between reducing carbohydrates to improve current immunotherapy is not clear. We thus aimed at analyzing the effects of different glucose levels on the tumor development, progression and the anti-tumoral immune response.

Methods

We correlated the clinical parameters of our LUAD cohort with different metabolic markers. Additionally, we performed cell culture experiments with A549 tumor cell line under different glucose levels. Lastly, we investigated the effect of low and high carbohydrate diet in an experimental murine model of lung cancer on the tumor progression and different immune subsets.

Results

Here we found a positive correlation between the body mass index (BMI), blood glucose levels, reduced overall survival (OS) and the expression of Insulin-like growth factor-1 receptor (IGF1R) in the lung tumoral region of patients with lung adenocarcinoma (LUAD). Furthermore, increasing extracellular glucose induced IGF1R expression in A549 LUAD cells. Functional studies in a murine model of LUAD demonstrated that, glucose restricted diet resulted in decreased tumor load in vivo. This finding was associated with increased presence of lung infiltrating cytotoxic CD8+ T effector memory (TEM), tissue resident memory T (TRM) and natural killer cells as well as reduced IGFR mRNA expression, suggesting that glucose restriction regulates lung immunity in the tumor microenvironment.

Conclusions

These results indicate that, glucose restricted diet improves lung immune responses of the host and suppresses tumor growth in experimental lung adenocarcinoma. As glucose levels in LUAD patients were negatively correlated to postoperative survival rates, glucose-restricted diet emerges as therapeutic avenue for patients with LUAD.

Clickable Albumin Nanoparticles for Pretargeted Drug Delivery toward PD-L1 Overexpressing Tumors in Combination Immunotherapy

We present a simple methodology to design a pretargeted drug delivery system, based on clickable anti-programmed death ligand 1 (anti-PD-L1) antibodies (Abs) and clickable bovine serum albumin (BSA) nanoparticles (NPs). Pretargeted drug delivery is based on the decoupling of a targeting moiety and a drug-delivering vector which can then react in vivo after separate injections. This may be key to achieve active targeting of drug-delivering NPs toward cancerous tissue. In pretargeted approaches, drug-delivering NPs were observed to accumulate in a higher amount in the targeted tissue due to shielding-related enhanced blood circulation and size-related enhanced tissue penetration. In this work, BSA NPs were produced using the solvent precipitation methodology that renders colloidally stable NPs, which were subsequently functionalized with a clickable moiety based on chlorosydnone (Cl-Syd). Those reactive groups are able to specifically react with dibenzocyclooctyne (DBCO) groups in a click-type fashion, reaching second-order reaction rate constants as high as 1.9 M^-1·s^-1, which makes this reaction highly suitable for in vivo applications. The presence of reactive Cl-Syd was demonstrated by reacting the functionalized NPs with a DBCO-modified sulfo-cyanine-5 dye. With this reaction, it was possible to infer the number of reactive moieties per NPs. Finally, and with the aim of demonstrating the suitability of this system to be used in pretargeted strategies, functionalized fluorescent NPs were used to label H358 cells with a clickable anti-PD-L1 Ab, applying the reaction between Cl-Syd and DBCO as corresponding clickable groups. The results of these experiments demonstrate the bio-orthogonality of the system to perform the reaction in vitro, in a period as short as 15 min.

Combination gemcitabine and PD-L1xCD3 bispecific T cell engager (BiTE) enhances T lymphocyte cytotoxicity against cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is a lethal cancer with rapid progression and poor survival. Novel and more effective therapies than those currently available are, therefore, urgently needed. Our research group previously reported the combination of gemcitabine and cytotoxic T lymphocytes to be more effective than single-agent treatment for the elimination of CCA cells. However, gemcitabine treatment of CCA cells upregulates the expression of an immune checkpoint protein (programmed death-ligand 1 [PD-L1]) that consequently inhibits the cytotoxicity of T lymphocytes. To overcome this challenge and take advantage of PD-L1 upregulation upon gemcitabine treatment, we generated recombinant PD-L1xCD3 bispecific T cell engagers (BiTEs) to simultaneously block PD-1/PD-L1 signaling and recruit T lymphocytes to eliminate CCA cells. Two recombinant PD-L1xCD3 BiTEs (mBiTE and sBiTE contain anti-PD-L1 scFv region from atezolizumab and from a published sequence, respectively) were able to specifically bind to both CD3 on T lymphocytes, and to PD-L1 overexpressed after gemcitabine treatment on CCA (KKU213A, KKU055, and KKU100) cells. mBiTE and sBiTE significantly enhanced T lymphocyte cytotoxicity against CCA cells, especially after gemcitabine treatment, and their magnitudes of cytotoxicity were positively associated with the levels of PD-L1 expression. Our findings suggest combination gemcitabine and PD-L1xCD3 BiTE as a potential alternative therapy for CCA.

Artificial intelligence to identify genetic alterations in conventional histopathology

Precision oncology relies on the identification of targetable molecular alterations in tumor tissues. In many tumor types, a limited set of molecular tests is currently part of standard diagnostic workflows. However, universal testing for all targetable alterations, especially rare ones, is limited by the cost and availability of molecular assays. From 2017 to 2021, multiple studies have shown that artificial intelligence (AI) methods can predict the probability of specific genetic alterations directly from conventional hematoxylin and eosin (H&E) tissue slides. Although these methods are currently less accurate than gold-standard testing (e.g. immunohistochemistry, polymerase chain reaction or next-generation sequencing), they could be used as pre-screening tools to reduce the workload of genetic analyses. In this systematic literature review, we summarize the state of the art in predicting molecular alterations from H&E using AI. We found that AI methods perform reasonably well across multiple tumor types, although few algorithms have been broadly validated. In addition, we found that genetic alterations in FGFR, IDH, PIK3CA, BRAF, TP53 and DNA repair pathways are predictable from H&E in multiple tumor types, while many other genetic alterations have rarely been investigated or were only poorly predictable. Finally, we discuss the next steps for the implementation of AI-based surrogate tests in diagnostic workflows. This article is protected by copyright. All rights reserved.

Immune checkpoint silencing using RNAi-incorporated nanoparticles enhances antitumor immunity and therapeutic efficacy compared with antibody-based approaches

BACKGROUND

Cytotoxic CD8⁺ T cell-based cancer immunotherapy has been extensively studied and applied, however, tumor cells are known to evade immune responses through the expression of immune checkpoints, such as programmed death ligand 1 (PD-L1). To overcome these issues, antibody-based immune checkpoint blockades (eg, antiprogrammed cell death 1 (anti-PD-1) and anti-PD-L1) have been revolutionized to improve immune responses. However, their therapeutic efficacy is limited to 15%-20% of the overall objective response rate. Moreover, PD-L1 is secreted from tumor cells, which can interrupt antibody-mediated immune reactions in the tumor microenvironment.

METHODS

We developed poly(lactic-co-glycolic acid) nanoparticles (PLGA-NPs) encapsulating PD-L1 small interfering RNA (siRNA) and PD-1 siRNA, as a delivery platform to silence immune checkpoints. This study used the TC-1 and EG7 tumor models to determine the potential therapeutic efficacy of the PLGA (PD-L1 siRNA+PD-1 siRNA)-NPs, on administration twice per week for 4 weeks. Moreover, we observed combination effect of PLGA (PD-L1 siRNA+PD-1 siRNA)-NPs and PLGA (antigen+adjuvant)-NPs using TC-1 and EG7 tumor-bearing mouse models.

RESULTS

PLGA (PD-L1 siRNA+PD-1 siRNA)-NPs boosted the host immune reaction by restoring CD8⁺ T cell function and promoting cytotoxic CD8⁺ T cell responses. We demonstrated that the combination of NP-based therapeutic vaccine and PLGA (siRNA)-NPs resulted in significant inhibition of tumor growth compared with the control and antibody-based treatments (p<0.001). The proposed system significantly inhibited tumor growth compared with the antibody-based approaches.

CONCLUSION

Our findings suggest a potential combination approach for cancer immunotherapy using PLGA (PD-L1 siRNA+PD-1 siRNA)-NPs and PLGA (antigen+adjuvant)-NPs as novel immune checkpoint silencing agents.

Programmed death ligand 1 signals in cancer cells

The paradigm of surface-expressed programmed death ligand 1 (PDL1) signalling to immune cell programmed death 1 (PD1) to inhibit antitumour immunity has helped to develop effective and revolutionary immunotherapies using antibodies blocking these cell-extrinsic interactions. The recent discovery of cancer cell-intrinsic PDL1 signals has broadened understanding of pathologic tumour PDL1 signal consequences that now includes control of tumour growth and survival pathways, stemness, immune effects, DNA damage responses and gene expression regulation. Many such effects are PD1-independent. These insights demonstrate that the prevailing cell-extrinsic PDL1 signalling paradigm is useful, but incomplete in important respects. This Perspective discusses historical and recent advances in understanding cancer cell-intrinsic PDL1 signals, mechanisms for signal controls and important immunopathologic consequences including resistance to cytotoxic agents, targeted small molecules and immunotherapies. Cancer cell-intrinsic PDL1 signals present novel drug discovery targets and also have potential as reliable treatment response biomarkers. Cancer cell-intrinsic PD1 signals and cell-intrinsic PDL1 signals in non-cancer cells are discussed briefly, as are PDL1 signals from soluble and vesicle-bound PDL1 and PDL1 isoforms. We conclude with suggestions for addressing the most pressing challenges and opportunities in this rapidly developing field.

PD-L1 mediates lung fibroblast to myofibroblast transition through Smad3 and β-catenin signaling pathways

Programmed death ligand-1 (PD-L1) is an immune checkpoint protein that has been linked with idiopathic pulmonary fibrosis (IPF) and fibroblast to myofibroblast transition (FMT). However, it remains largely unclear how PD-L1 mediates this process. We found significantly increased PD-L1 in the lungs of idiopathic pulmonary fibrosis patients and mice with pulmonary fibrosis induced by bleomycin and TGF-β. In primary human lung fibroblasts (HLFs), TGF-β induced PD-L1 expression that is dependent on both Smad3 and p38 pathways. PD-L1 knockdown using siRNA significantly attenuated TGF-β-induced expression of myofibroblast markers α-SMA, collagen-1, and fibronectin in normal and IPF HLFs. Further, we found that PD-L1 interacts with Smad3, and TGF-β induces their interaction. Interestingly, PD-L1 knockdown reduced α-SMA reporter activity induced by TGF-β in HLFs, suggesting that PD-L1 might act as a co-factor of Smad3 to promote target gene expression. TGF-β treatment also phosphorylates GSK3β and upregulates β-catenin protein levels. Inhibiting β-catenin signaling with the pharmaceutical inhibitor ICG001 significantly attenuated TGF-β-induced FMT. PD-L1 knockdown also attenuated TGF-β-induced GSK3β phosphorylation/inhibition and β-catenin upregulation, implicating GSK3β/β-catenin signaling in PD-L1-mediated FMT. Collectively, our findings demonstrate that fibroblast PD-L1 may promote pulmonary fibrosis through both Smad3 and β-catenin signaling and may represent a novel interventional target for IPF.

Differential expression of PD‑L1 and PD‑L2 is associated with the tumor microenvironment of TILs and M2 TAMs and tumor differentiation in non‑small cell lung cancer

To improve the treatment strategy of immune-checkpoint inhibitors for non-small cell lung cancer (NSCLC), a comprehensive analysis of programmed death-ligand (PD-L)1 and PD-L2 expression is clinically important. The expression of PD-L1 and PD-L2 on both tumor cells (TCs) and tumor-infiltrating immune cells (ICs) was investigated, with respect to tumor-infiltrating lymphocytes (TILs) and M2 tumor-associated macrophages (TAMs), which are key components of the tumor microenvironment, in 175 patients with resected NSCLC. The TIL and M2 TAM densities were associated with the expression of PD-L1 on the two TCs (both P<0.0001) and ICs (both P<0.0001). The TIL and M2 TAM densities were also associated with the expression of PD-L2 on both TCs (P=0.0494 and P=0.0452, respectively) and ICs (P=0.0048 and P=0.0125, respectively). However, there was no correlation between the percentage of PD-L1-positive TCs and the percentage of PD-L2-positive TCs (r=0.019; P=0.8049). Meanwhile, tumor differentiation was significantly associated with the PD-L1 expression on TCs and ICs (P=0.0002 and P<0.0001, respectively). By contrast, tumor differentiation was inversely associated with the PD-L2 expression on both TCs and ICs (P=0.0260 and P=0.0326, respectively). In conclusion, the combined evaluation of PD-L1 and PD-L2 expression could be clinically important in the treatment strategy of immune-checkpoint inhibitors in patients with NSCLC. In particular, the evaluation of PD-L2 expression may be necessary for patients with PD-L1-negative NSCLC.

Dual-sgRNA CRISPR/Cas9 knockout of PD-L1 in human U87 glioblastoma tumor cells inhibits proliferation, invasion, and tumor-associated macrophage polarization

Programmed death ligand 1 (PD-L1) plays a key role in glioblastoma multiforme (GBM) immunosuppression, vitality, proliferation, and migration, and is therefore a promising target for treating GBM. CRISPR/Cas9-mediated genomic editing can delete both cell surface and intracellular PD-L1. This systemic deliverable genomic PD-L1 deletion system can be used as an effective anti-GBM therapy by inhibiting tumor growth and migration, and overcoming immunosuppression. To target PD-L1 for CRISPR/Cas9 gene editing, we first identified two single guide RNA (sgRNA) sequences located on PD-L1 exon 3. The first sgRNA recognizes the forward strand of human PD-L1 near the beginning of exon 3 that allows editing by Cas9 at approximately base pair 82 (g82). The second sgRNA recognizes the forward strand of exon 3 that directs cutting at base pair 165 (g165). A homology-directed repair template (HDR) combined with the dual-sgRNAs was used to improve PD-L1 knockout specificity and efficiency. sgRNAs g82 and g165 were cloned into the multiplex CRISPR/Cas9 assembly system and co-transfected with the HDR template in human U87 GBM cells (g82/165 + HDR). T7E1 analysis suggests that the dual-sgRNA CRISPR/Cas9 strategy with a repair template was capable of editing the genomic level of PD-L1. This was further confirmed by examining PD-L1 protein levels by western blot and immunofluorescence assays. Western blot analysis showed that the dual-sgRNAs with the repair template caused a 64% reduction of PD-L1 protein levels in U87 cells, while immunostaining showed a significant reduction of intracellular PD-L1. PD-L1 deletion inhibited proliferation, growth, invasion and migration of U87 cells, indicating intracellular PD-L1 is necessary for tumor progression. Importantly, U87 cells treated with g82/165 + HDR polarized tumor-associated macrophages (TAM) toward an M1 phenotype, as indicated by an increase in TNF-α and a decrease in IL-4 secretions. This was further confirmed with flow cytometry that showed an increase in the M1 markers Ly6C + and CD80 +, and a decrease in the M2 marker CD206 + both in vitro and in vivo. Utilizing dual-sgRNAs and an HDR template with the CRISPR/Cas9 gene-editing system is a promising avenue for the treatment of GBM.

Soluble Programmed Death-Ligand 1 (sPD-L1) is Elevated in Aggressive Prostate Cancer Disease Among African Men

Introduction

Programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1)-targeted immunotherapies have become a new mode of treatment for several tumours; however, there is limited evidence on the expression and prognostic value of PD-1/PD-L1 in prostate cancer, especially in African men.

Methods

Plasma concentrations of PD-L1/PD-1 were assessed using enzyme-linked immunosorbent assay in patients with prostate cancer and normal healthy controls at the Uganda Cancer Institute. The associations between plasma PD-L1/PD-1 concentration levels and serum prostate-specific antigen (PSA) levels, Gleason scores, age, and body mass index (BMI) were determined.

Results

We found significant differences in the median plasma concentrations of PD-L1 and PD-1 immune checkpoint molecules between prostate cancer cases and normal healthy controls of 0.285 vs 0.035 (p = 0.001) and 0.596 vs 0.355 (p = 0.017), respectively. We found no significant association between age, serum PSA levels, BMI and Gleason scores, and PD-1 among patients with prostate cancer and controls. However, elevated levels of PD-L1 were significantly associated with higher Gleason scores among patients with prostate cancer (p = 0.014).

Conclusions

Elevated PD-L1 levels were statistically significantly linked to high Gleason scores. These results may guide clinicians in assessing the prognosis of patients individually and selecting patients who will be suitable candidates for anti-PD-L1 immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40487-022-00184-6.

PD-L1 interacts with Frizzled 6 to activate β-catenin and form a positive feedback loop to promote cancer stem cell expansion

Cancer stem cells (CSCs) drive tumor initiation, progression, metastasis, and drug resistance. We report here that programmed cell death ligand 1 (PD-L1) is constitutively expressed in cancer cells to maintain and expand CSC through a novel mechanism in addition to promoting cancer cell immune evasion. We discovered that PD-L1 interacts with receptor Frizzled 6 to activate β-catenin signaling and increase β-catenin-targeted gene expression, such as a putative stem cell marker leucine-rich-repeat-containing G-protein-coupled receptor 5. Blockage of PD-L1 function, using a specific small hairpin RNA or a specific antibody, inhibits disease progression by reducing the CSC population in both colorectal and breast tumors. Moreover, β-catenin conversely regulates PD-L1 expression through a β-catenin complex binding site in the PD-L1 promoter. Our discoveries reveal that besides assistant tumor cell immune escaping, PD-L1 and β-catenin signaling form a positive feedback loop to promote cancer progression through CSC maintenance and expansion.

Immunosuppressive Traits of the Hybrid Epithelial/Mesenchymal Phenotype

Recent preclinical and clinical data suggests enhanced metastatic fitness of hybrid epithelial/mesenchymal (E/M) phenotypes, but mechanistic details regarding their survival strategies during metastasis remain unclear. Here, we investigate immune-evasive strategies of hybrid E/M states. We construct and simulate the dynamics of a minimalistic regulatory network encompassing the known associations among regulators of EMT (epithelial-mesenchymal transition) and PD-L1, an established immune-suppressor. Our simulations for the network consisting of SLUG, ZEB1, miR-200, CDH1 and PD-L1, integrated with single-cell and bulk RNA-seq data analysis, elucidate that hybrid E/M cells can have high levels of PD-L1, similar to those seen in cells with a full EMT phenotype, thus obviating the need for cancer cells to undergo a full EMT to be immune-evasive. Specifically, in breast cancer, we show the co-existence of hybrid E/M phenotypes, enhanced resistance to anti-estrogen therapy and increased PD-L1 levels. Our results underscore how the emergent dynamics of interconnected regulatory networks can coordinate different axes of cellular fitness during metastasis.

PD-L1 expression in megakaryocytes and its clinicopathological features in primary myelofibrosis patients

Myeloproliferative neoplasms (MPNs) are characterized by upregulation of proinflammatory cytokines and immune dysregulation, which provide a reasonable basis for immunotherapy in patients. Megakaryocytes are crucial in the pathogenesis of primary myelofibrosis (PMF), the most clinically aggressive subtype of MPN. In this study, we aimed to explore PD-L1 (programmed death-ligand 1) expression in megakaryocytes and its clinical implications in PMF. We analyzed PD-L1 expression on megakaryocytes in PMF patients by immunohistochemistry and correlated the results with clinicopathological features and molecular aberrations. We employed a two-tier grading system considering both the proportion of cells positively stained and the intensity of staining. Among the 85 PMF patients, 41 (48%) showed positive PD-L1 expression on megakaryocytes with the immune-reactive score ranging from 1 to 12. PD-L1 expression correlated closely with higher white blood cell count (p = 0.045), overt myelofibrosis (p = 0.010), JAK2V617F mutation (p = 0.011), and high-molecular risk mutations (p = 0.045), leading to less favorable overall survival in these patients (hazard ratio 0.341, 95% CI 0.135-0.863, p = 0.023). Our study provides unique insights into the interaction between immunologic and molecular phenotypes in PMF patients. Future work to explore the translational potential of PD-L1 in the clinical setting is needed.

NLRC5 Might Promote Endometrial Cancer Progression by Inducing PD-L1 Expression

Aims: The NOD-like receptor (NLR) family, caspase recruitment (CARD) domain containing 5 (NLRC5) was dysregulated in endometrial cancer (EC). However, the potential regulatory mechanisms of NLRC5 in EC remained unclear. We aimed to explore whether NLRC5 could regulate the programmed cell death protein ligand 1 (PD-L1) in EC. We also investigated the related molecular which led to the inactivation of NLRC5 in EC. Methods: The expressions of NLRC5 and PD-L1 in endometrium tissue microarray were detected by immunohistochemistry. Pearson's correlation analysis was performed to detect the expression correlation between NLRC5 and PD-L1. Immunofluorescence staining, western blotting, and quantitative real-time PCR (qRT-PCR) were used to detect the role of NLRC5 in PD-L1 in EC cell lines. The somatic mutation in EC patients was detected by whole-exome sequencing (WGS). Results: NLRC5 was downregulated in the endometrium of EC patients when compared to those in the normal endometrium. The level of PD-L1 in the endometrium of EC patients was higher when compared to those in the normal endometrium. There was a negative expression correlation between NLRC5 and PD-L1. NLRC5 could promote the expression of PD-L1 in EC cell lines. The mutations of ANKRD20A2, C2orf42, ADGRB3, AVPR2, GOLGA6C, and IPPK may lead to the downregulation of NLRC5 in EC patients. Conclusion: NLRC5 could inhibit the activation of PD-L1 in EC. Mutations of ANKRD20A2, C2orf42, ADGRB3, AVPR2, GOLGA6C, and IPPK may lead to the downregulation of NLRC5 in EC patients. Future study should investigate the mechanism of NLRC5 in PD-L1, as well as the mechanism of ANKRD20A2, C2orf42, ADGRB3, AVPR2, GOLGA6C, and IPPK in NLRC5.

Meaningful connections: Interrogating the role of physical fibroblast cell-cell communication in cancer

As part of the connective tissue, activated fibroblasts play an important role in development and disease pathogenesis, while quiescent resident fibroblasts are responsible for sustaining tissue homeostasis. Fibroblastic activation is particularly evident in the tumor microenvironment where fibroblasts transition into tumor-supporting cancer-associated fibroblasts (CAFs), with some CAFs maintaining tumor-suppressive functions. While the tumor-supporting features of CAFs and their fibroblast-like precursors predominantly function through paracrine chemical communication (e.g., secretion of cytokine, chemokine, and more), the direct cell-cell communication that occurs between fibroblasts and other cells, and the effect that the remodeled CAF-generated interstitial extracellular matrix has in these types of cellular communications, remain poorly understood. Here, we explore the reported roles fibroblastic cell-cell communication play within the cancer stroma context and highlight insights we can gain from other disciplines.

Involvement of PD-L1-mediated Tumor Intrinsic Signaling and Immune Suppression in Tumorigenic Effect of α-Tocopherol

Numerous studies have shown that the different isoforms vitamin E have distinct activity on carcinogenesis. α-Tocopherol (α-T), the most abundant vitamin E in certain types of food and animal tissues, has demonstrated a cancer-promoting effect in a number of human clinical trials and pre-clinical studies, whereas the γ- and δ- forms of Tocopherols and Tocotrienols have exhibited significant anticancer effect in various pre-clinical studies. However, the mechanisms underlying the tumorigenic effect of α-T have not yet been fully understood. In the present study, we found that α-T was able to activate Programmed death-ligand 1 (PD-L1)-mediated tumor-intrinsic signaling and immune suppression via JAK/STAT3-dependent transcriptional and ERK-dependent posttranscriptional mechanism. In line with PD-L1 induction, α-T treatment increased cancer cell viability in vitro and promoted tumor growth in LLC xenograft mouse model. The findings of the present study for the first time provided evidence that PD-L1-mediated tumor-intrinsic and immune escape mechanism contributed to the tumorigenic effect of α-T.

L-Type Amino Acid Transporter 1 Regulates Cancer Stemness and the Expression of Programmed Cell Death 1 Ligand 1 in Lung Cancer Cells

The l-type amino acid transporter 1 (LAT1) is a membranous transporter that transports neutral amino acids for cells and is dysregulated in various types of cancer. Here, we first observed increased LAT1 expression in pemetrexed-resistant non-small cell lung cancer (NSCLC) cells with high cancer stem cell (CSC) activity, and its mRNA expression level was associated with shorter overall survival in the lung adenocarcinoma dataset of the Cancer Genome Atlas database. The inhibition of LAT1 by a small molecule inhibitor, JPH203, or by RNA interference led to a significant reduction in tumorsphere formation and the downregulation of several cancer stemness genes in NSCLC cells through decreased AKT serine/threonine kinase (AKT)/mammalian target of rapamycin (mTOR) activation. The treatment of the cell-permeable leucine derivative promoted AKT/mTOR phosphorylation and reversed the inhibitory effect of JPH203 in the reduction of CSC activity in pemetrexed-resistant lung cancer cells. Furthermore, we observed that LAT1 silencing caused the downregulation of programmed cell death 1 ligand 1 (PD-L1) on lung cancer cells. The PD-L1⁺/LAT1⁺ subpopulation of NSCLC cells displayed great CSC activity with increased expression of several cancer stemness genes. These data suggest that LAT1 inhibitors can serve as anti-CSC agents and could be used in combination with immune checkpoint inhibitors in lung cancer therapy.

Mild hyperthermia promotes immune checkpoint blockade-based immunotherapy against metastatic pancreatic cancer using size-adjustable nanoparticles

Immune checkpoint blockade treatment is one of the most promising immunotherapies, which exhibits promising therapeutic effects on inhibition of metastasis. However, immunotherapy has little effect on pancreatic cancer, due to its extensive fibrotic matrix and immunosuppressive tumor microenvironment. Mild hyperthermia induced by photothermal therapy (PTT) has been proven to activate the immune responses in the tumor microenvironment. Herein, we designed a combine strategy of mild hyperthermia and immune checkpoint blockade (BMS-202) treatment with size-adjustable thermo- and fibrotic matrix- sensitive liposomes (HSA-BMS@CAP-ILTSL), in which BMS-202 loaded small-sized albumin nanoparticle (HSA-BMS) was encapsulated. Mild hyperthermia reduced the tumor hypoxia, relieved the interstitial pressure and increased the recruitment of endogenous immune cells in tumors. In the meantime, small-sized HSA-BMS was released from large-sized HSA-BMS@CAP-ILTSL in response to fibroblast activation protein-α (FAP-α) and near-infrared (NIR) laser, and enhanced the immunological responses by recovering the activity of T lymphocytes, accompanied by secreting relevant cytokines (TNF-α and IFN-γ). The combined therapy (HSA-BMS@CAP-ILTSL) could not only significantly suppress the tumor growth in vivo, but also decrease the amounts of metastatic nodules in distant organs. These results suggested that size-adjustable nanoparticles had a great potential in the treatment of metastatic pancreatic cancer. STATEMENT OF SIGNIFICANCE: The desmoplastic stroma and hypoperfusion of pancreatic cancer imposed physical barriers to effective therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. We constructed size-adjustable thermo- and fibrotic matrix- sensitive liposomes (HSA-BMS@CAP-ILTSL) with size around 120 nm, where small sized albumin nanoparticle (10 nm) of immune checkpoint inhibitor (HSA-BMS) were encapsulated inside. Mild hyperthermia not only contributed to release HSA-BMS for penetration (blocking the immunosuppressive signals deep in the tumor), but enhanced tumor blood perfusion for infiltration of endogenous immune cells. In the two-pronged treatment, the pancreatic cancer immunotherapy significantly enhanced and the risk of cancer metastasis was reduced. Overall, the strategy provides a promising approach to increase drug accumulation and improve the anti-tumor immune activity in pancreatic cancer.

Current understanding of cancer-intrinsic PD-L1: regulation of expression and its protumoral activity

In the last decade, we have witnessed an unprecedented clinical success in cancer immunotherapies targeting the programmed cell-death ligand 1 (PD-L1) and programmed cell-death 1 (PD-1) pathway. Besides the fact that PD-L1 plays a key role in immune regulation in tumor microenvironment, recently a plethora of reports has suggested a new perspective of non-immunological functions of PD-L1 in the regulation of cancer intrinsic activities including mesenchymal transition, glucose and lipid metabolism, stemness, and autophagy. Here we review the current understanding on the regulation of expression and intrinsic protumoral activity of cancer-intrinsic PD-L1.

Anticancer Activities of Hesperidin via Suppression of Up-Regulated Programmed Death-Ligand 1 Expression in Oral Cancer Cells

Up-regulated expression of programmed death-ligand 1 (PD-L1) by interferon-gamma (IFN-γ) has been associated with promotion of cancer cell survival and tumor cell escape from anti-tumor immunity. Therefore, a blockade of PD-L1 expression can potentially be used as a molecular target for cancer therapy. The aim of this study was to investigate whether suppression of IFN-γ induced PD-L1 expression in two oral cancer cell lines, HN6 and HN15, by hesperidin effectively decreased cell proliferation and migration. Further, our objective was to elucidate the involvement of the signal transducer and activator of transcription 1 (STAT1) and STAT3 in the inhibition of induced PD-L1 expression by hesperidin. Our findings indicate that IFN-γ induced expression of PD-L1 protein in HN6 and HN15 via phosphorylation of STAT1 and STAT3 and that hesperidin significantly reduced that induction through suppression of phosphorylated STAT1 and STAT3 in both cell lines. Moreover, hesperidin also significantly decreased the viability, proliferation, migration, and invasion of both cell lines. In conclusion, hesperidin exerted anticancer effects against oral cancer cells through the suppression of PD-L1 expression via inactivation of the STAT1 and STAT3 signaling molecules. The findings of this study support the use of hesperidin as a potential adjunctive treatment for oral cancer.

Expression of immune checkpoint PD-1 in non-small cell lung cancer is associated with tumor cell DNA-dependent protein kinase

Immunotherapy using immune checkpoint inhibitors has demonstrated durable responses and has significantly improved survival in patients with non-small cell lung cancer (NSCLC). Moreover, immunotherapy is increasingly used in combination with cytotoxic treatments such as chemotherapy and radiotherapy. Although the combined treatments are more effective, the underling mechanisms that lead to higher antitumor activity are not fully understood. Therefore, the aim of the current retrospective study was to determine the relationship between expression of immune checkpoints [programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1)] and the enzyme DNA-dependent protein kinase (DNA-PK), which is part of a key pathway involved in the repair of cytotoxic cancer therapy induced damage. Surgically excised NSCLC tissues (n=121) were histologically examined for overall extent of inflammation (score 0-3). Expression levels of PD-1 (number of PD-1 positive cells), PD-L1 [tumor proportion score (TPS); %] and DNA-PK (proportion of DNA-PK positive tumor cells; %) were determined using immunohistochemistry. Expressions of these markers were compared in different clinicopathological subgroups and later used for nonparametric Spearman correlation analysis to determine associations. In patients with NSCLC, PD-1 was significantly expressed in males (P=0.030) and in patients with no or trivial inflammation scores (P=0.030). PD-L1 expression was also significantly higher in current smokers (P=0.025). Correlation analysis was based on the individual values of patients and revealed a significant association between one of the targets of immune checkpoint inhibitors and tumor cell DNA-PK. Tumors with higher numbers of PD-1 positive cells also demonstrated higher tumor cell DNA-PK expressions (P=0.027). The results demonstrated a significant positive correlation between the PD-1/PD-L1 axis and tumor cell DNA-PK expression in patients with NSCLC. Further studies are required to clarify the significance of this correlation and its effect on the efficacy of immunotherapy and cytotoxic cancer therapy combinations.

Immune checkpoint inhibitors: a new landscape for extensive stage small cell lung cancer treatment

Introduction: Landscape of Extensive Stage (ES)-SCLC treatment has been unchanged over the years. Chemotherapy, mostly based on cisplatin and etoposide, remained the standard-of-care for patients with ES-SCLC for almost 40 years. Recently, immune check points inhibitors have emerged marking a turning point for ES-SCLC treatmentAreas covered: Aim of the paper is to discuss ICIs impact on ES-SCLC treatment algorithms, review current clinical trials, and explore future perspectives.Expert opinion: A growing body of evidence supports ICI-containing regimens as a new mainstay of ES-SCLC treatment. Whether subgroups of SCLC patients may have greater survival benefits from ICIs treatment needs to be better defined. Understanding the impact of tumor microenvironment and identifying reliable predictive and/or prognostic biomarkers will be fundamental to move toward a personalized treatment approach leading to improved survival.

Inhibition of STAT3/PD-L1 and Activation of miR193a-5p Are Critically Involved in Apoptotic Effect of Compound K in Prostate Cancer Cells

Since the signal transducer and activator of transcription 3 (STAT3)/programmed death-ligand 1 (PD-L1) signaling plays an important role in tumor-immune microenvironments, in the present study, the role of STAT3/PD-L1 signaling in the apoptotic mechanism of an active ginseng saponin metabolite compound K (CK) was investigated in human prostate cancer cells. Here, CK exerted significant cytotoxicity without hurting RWPE1 normal prostate epithelial cells, increased sub-G1 and cleavage of Poly ADP-ribose polymerase (PARP) and attenuated the expression of pro-PARP and Pro-cysteine aspartyl-specific protease3 (pro-caspase-3) in LANCap, PC-3 and DU145 cells. Further, CK attenuated the expression of p-STAT3 and PD-L1 in DU145 cells along with disrupted the binding of STAT3 to PD-L1. Furthermore, CK effectively abrogated the expression of p-STAT3 and PD-L1 in interferon-gamma (INF-γ)-stimulated DU145cells. Additionally, CK suppressed the expression of vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β), interleukin 6 (IL-6) and interleukin 10 (IL-10) as immune escape-related genes in DU145 cells. Likewise, as STAT3 targets genes, the expression of CyclinD1, c-Myc and B-cell lymphoma-extra-large (Bcl-xL) was attenuated in CK-treated DU145 cells. Notably, CK upregulated the expression of microRNA193a-5p (miR193a-5p) in DU145 cells. Consistently, miR193a-5p mimic suppressed p-STAT3, PD-L1 and pro-PARP, while miR193a-5p inhibitor reversed the ability of CK to attenuate the expression of p-STAT3, PD-L1 and pro-PARP in DU145 cells. Taken together, these findings support evidence that CK induces apoptosis via the activation of miR193a-5p and inhibition of PD-L1 and STAT3 signaling in prostate cancer cells.

PD-L1 is upregulated via BRD2 in head and neck squamous cell carcinoma models of acquired cetuximab resistance

BACKGROUND

Tumor models resistant to EGFR tyrosine kinase inhibitors or cisplatin express higher levels of the immune checkpoint molecule PD-L1. We sought to determine whether PD-L1 expression is elevated in head and neck squamous cell carcinoma (HNSCC) models of acquired cetuximab resistance and whether the expression is regulated by bromodomain and extraterminal domain (BET) proteins.

METHODS

Expression of PD-L1 was assessed in HNSCC cell line models of acquired cetuximab resistance. Proteolysis targeting chimera (PROTAC)- and RNAi-mediated targeting were used to assess the role of BET proteins.

RESULTS

Cetuximab-resistant HNSCC cells expressed elevated PD-L1 compared to cetuximab-sensitive controls. Treatment with the BET inhibitor JQ1, the BET PROTAC MZ1, or RNAi-mediated knockdown of BRD2 decreased PD-L1 expression. Knockdown of BRD2 also reduced the elevated levels of PD-L1 seen in a model of acquired cisplatin resistance.

CONCLUSIONS

PD-L1 is significantly elevated in HNSCC models of acquired cetuximab and cisplatin resistance where BRD2 is the primary regulator.

Molecular Pathways and Druggable Targets in Head and Neck Squamous Cell Carcinoma

Head and neck cancers are a heterogeneous group of neoplasms, affecting an ever increasing global population. Despite advances in diagnostic technology and surgical approaches to manage these conditions, survival rates have only marginally improved and this has occurred mainly in developed countries. Some improvements in survival, however, have been a result of new management and treatment approaches made possible because of our ever-increasing understanding of the molecular pathways triggered in head and neck oncogenesis, and the growing understanding of the abundant heterogeneity of this group of cancers. Some important pathways are common to other solid tumours, but their impact on reducing the burden of head and neck disease has been less than impressive. Other less known and little-explored pathways may hold the key to the development of potential druggable targets. The extensive work carried out over the last decade, mostly utilising next generation sequencing has opened up the development of many novel approaches to head and neck cancer treatment. This paper explores our current understanding of the molecular pathways of this group of tumours and outlines associated druggable targets which are deployed as therapeutic approaches in head and neck oncology with the ultimate aim of improving patient outcomes and controlling the personal and economic burden of head and neck cancer.

Extracellular Vesicle Mediated Tumor-Stromal Crosstalk Within an Engineered Lung Cancer Model

Tumor-stromal interactions within the tumor microenvironment (TME) influence lung cancer progression and response to therapeutic interventions, yet traditional in vitro studies fail to replicate the complexity of these interactions. Herein, we developed three-dimensional (3D) lung tumor models that mimic the human TME and demonstrate tumor-stromal crosstalk mediated by extracellular vesicles (EVs). EVs released by tumor cells, independent of p53 status, and fibroblasts within the TME mediate immunomodulatory effects; specifically, monocyte/macrophage polarization to a tumor-promoting M2 phenotype within this 3D-TME. Additionally, immune checkpoint inhibition in a 3D model that included T cells showed an inhibition of tumor growth and reduced hypoxia within the TME. Thus, perfused 3D tumor models incorporating diverse cell types provide novel insights into EV-mediated tumor-immune interactions and immune-modulation for existing and emerging cancer therapies.

MiR-200c-3p Contrasts PD-L1 Induction by Combinatorial Therapies and Slows Proliferation of Epithelial Ovarian Cancer through Downregulation of β-Catenin and c-Myc

Conventional/targeted chemotherapies and ionizing radiation (IR) are being used both as monotherapies and in combination for the treatment of epithelial ovarian cancer (EOC). Several studies show that these therapies might favor oncogenic signaling and impede anti-tumor responses. MiR-200c is considered a master regulator of EOC-related oncogenes. In this study, we sought to investigate if chemotherapy and IR could influence the expression of miR-200c-3p and its target genes, like the immune checkpoint PD-L1 and other oncogenes in a cohort of EOC patients’ biopsies. Indeed, PD-L1 expression was induced, while miR-200c-3p was significantly reduced in these biopsies post-therapy. The effect of miR-200c-3p target genes was assessed in miR-200c transfected SKOV3 cells untreated and treated with olaparib and IR alone. Under all experimental conditions, miR-200c-3p concomitantly reduced PD-L1, c-Myc and β-catenin expression and sensitized ovarian cancer cells to olaparib and irradiation. In silico analyses further confirmed the anti-correlation between miR-200c-3p with c-Myc and β-catenin in 46 OC cell lines and showed that a higher miR-200c-3p expression associates with a less tumorigenic microenvironment. These findings provide new insights into how miR-200c-3p could be used to hold in check the adverse effects of conventional chemotherapy, targeted therapy and radiation therapy, and offer a novel therapeutic strategy for EOC.

EZH2-mediated epigenetic suppression of SH3BGRL potently inhibits lung cancer progression

Lung cancer is the leading cause of cancer-related deaths worldwide. Lung cancer stem cells (CSCs) are a small population of cancer cells with self-renewal, therapeutic resistance, and tumor relapse capability. Yet the molecular mechanisms underlying lung CSCs self-renewal remain largely unknown. Here, we report that SH3BGRL were down-regulated in lung cancer tissues comparing with normal lung tissues and SH3BGRL low expression was correlated with the poor clinical outcomes of patients with lung cancer. Moreover, SH3BGRL was also weakly expressed in lung CSCs compared with its corresponding lung cancer cells. We first characterize that EZH2 directly binds to SH3BGRL promoter and transcriptional represses SH3BGRL expression in epigenetic level. Functionally, overexpression of SH3BGRL potently suppresses Lung CSCs self-renewal in vitro. The gain of function study reveals that SH3BGRL acts as a novel tumor suppressor via inhibiting lung cancer cell proliferation and migration as well as Lung CSCs self-renewal in vitro. Collectively, our work demonstrates that SH3BGRL hold potential as a favorable prognostic marker and therapeutic target for patients with lung cancer in future.

PD-L1 Protein Expression in Middle Eastern Breast Cancer Predicts Favorable Outcome in Triple-Negative Breast Cancer

Programmed cell-death ligand 1 (PD-L1) has been shown to induce potent T-cell mediated anti-tumoral immunity. The significance of PD-L1 expression in the prognosis of breast cancer (BC) remains controversial and its prevalence and prognostic value in breast cancer from Middle Eastern ethnicity is lacking. A total of 1003 unselected Middle Eastern breast cancers were analyzed for PD-L1 expression using immunohistochemistry. PD-L1 expression, seen in 32.8% (329/1003) of cases, was significantly associated with poor prognostic indicators such as younger patients, high-grade tumors, estrogen-receptor (ER)-negative, progesterone-receptor (PR)-negative, and triple-negative breast cancers (TNBC) as well as high Ki-67 index. We also found a significant association between PD-L1 expression and deficient mismatch repair protein expression. No association was found between PD-L1 expression and clinical outcome. However, on further subgroup analysis, PD-L1 expression was found to be an independent marker for favorable overall survival and recurrence-free survival in TNBC. In conclusion, we demonstrated strong association between PD-L1 and mismatch repair deficiency in Middle Eastern BC patients and that PD-L1 overexpression in tumor cells was an independent prognostic marker in TNBCs from Middle Eastern ethnicity. Overall, these findings might help in the development of more appropriate treatment strategies for BC in Middle Eastern population.

PD-L1 Expression in Chinese Patients with Advanced Non-Small Cell Lung Cancer (NSCLC): A Multi-Center Retrospective Observational Study

Objective: This study aimed to investigate the prevalence of tumor programmed death-ligand 1 (PD-L1) expression in Chinese patients with advanced Non-Small Cell Lung Cancer (NSCLC). Methods: Tumor tissues with histologically confirmed stage IIIB/IV NSCLC were retrospectively obtained from 10 centers in China. PD-L1 expression was determined using the PD-L1 IHC 22C3 pharmDx kit (Agilent, Santa Clara, CA, USA) and the samples were repetitively assayed with the PD-L1 IHC 22C3 Ab concentrate (Agilent, Santa Clara, CA, USA). Results: Out of 901 patients who met the inclusion criteria, 879 (97.6%) had evaluable PD-L1 data. The number of patients with a PD-L1 tumor proportion score (TPS) < 1%, 1-49%, and ≥ 50% (corresponding to PD-L1 non-expression, low expression, and high expression) was 424 (48.2%), 266 (30.3%), and 189 (21.5%), respectively. PD-L1 expression was more likely to be found in patients younger than 75 years, men, current or former smokers, those with good performance status (PS) scores, and those with a wild-type epidermal growth factor receptor (EGFR). PD-L1 TPS ≥ 50% and ≥ 1% were respectively 28.0% and 50.2% among patients negative for both EGFR mutation and anaplastic lymphoma kinase (ALK) rearrangement. PD-L1 expression determined using the 22C3 antibody concentrate and pharmDx kit had comparable results. Conclusions: The prevalence of PD‑L1 expression in advanced NSCLC was consistent with that reported in the global EXPRESS study. Age, gender, smoking history, PS scores, and EGFR/ALK mutation status affected PD-L1 expression. The 22C3 antibody concentrate appears to be an alternative reagent for the PD-L1 assay.

Prognostic and clinicopathological value of PD-L2 in lung cancer: A meta-analysis

OBJECTIVE

The prognostic role of programmed death ligand-2 (PD-L2) expression in lung cancer has been widely studied, however, the results are controversial. Accordingly, we investigated the prognostic and clinicopathological value of PD-L2 in patients with lung cancer in this meta-analysis.

METHODS

Relevant studies were systematically searched in the PubMed, Web of Science, EMBASE, ClinicalTrials.gov., Scopus, and Cochrane Library until July 10, 2020. The hazard ratio (HR), odds ratio (OR), and their corresponding 95% confidence intervals (CIs) were calculated.

RESULTS

Thirteen studies with 3107 participants were included. High PD-L2 expression was associated with poor overall survival (OS) (HR 1.248, 95% CI: 1.071-1.455, p = 0.004) and worse disease-free survival (DFS)/progression-free survival (PFS)/relapse-free survival (RFS) (HR 1.224, 95% CI: 1.058-1.417, p = 0.007) in lung cancer. Furthermore, unfavorable OS was found in lung adenocarcinoma (HR 1.349, 95% CI: 1.051-1.731, p = 0.019), but not in other pathological types (HR 1.192, 95% CI: 0.982-1.447 p = 0.076) with higher PD-L2 expression in our subgroup analysis. Concerning the clinicopathological characteristics, high PD-L2 expression was associated with smoking (OR 0.725, 95% CI: 0.591-0.890, p = 0.002) and PD-L1 (OR 1.607, 95% CI:1.115-2.314, p = 0.011) and vascular invasion (OR 1.500, 95% CI: 1.022-2.203, p = 0.039).

CONCLUSION

PD-L2 overexpression might predict a poor prognosis in lung cancer patients after surgery. PD-L2 expression might be a potential biomarker for PD-1/PD-L1-targeted immunotherapy in lung cancer, which should be investigated in future studies.

WIP Modulates Oxidative Stress through NRF2/KEAP1 in Glioblastoma Cells

Due to their high metabolic rate, tumor cells produce exacerbated levels of reactive oxygen species that need to be under control. Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP) is a scaffold protein with multiple yet poorly understood functions that participates in tumor progression and promotes cancer cell survival. However, its participation in the control of oxidative stress has not been addressed yet. We show that WIP depletion increases the levels of reactive oxygen species and reduces the levels of transcription factor NRF2, the master regulator of redox homeostasis. We found that WIP stabilizes NRF2 by restraining the activity of its main NRF2 repressor, the E3 ligase adapter KEAP1, because the overexpression of a NRF2ΔETGE mutant that is resistant to targeted proteasome degradation by KEAP1 or the knock-down of KEAP1 maintains NRF2 levels in the absence of WIP. Mechanistically, we show that the increased KEAP1 activity in WIP-depleted cells is not due to the protection of KEAP1 from autophagic degradation, but is dependent on the organization of the Actin cytoskeleton, probably through binding between KEAP1 and F-Actin. Our study provides a new role of WIP in maintaining the oxidant tolerance of cancer cells that may have therapeutic implications.