β-Catenin regulates tumor-derived PD-L1

NDR1 mediates PD-L1 deubiquitination to promote prostate cancer immune escape via USP10

Prostate cancer (PCa) is one of the most common male genitourinary system malignancies. Despite the significant benefits of anti-PD-L1 immune checkpoint inhibitor therapy in other cancers, the reasons for its poor therapeutic efficacy in prostate cancer (PCa) remain unclear.NDR1 plays an important role in innate immunity, but its role in tumor immunity and immunotherapy has not been investigated. The role of NDR1 in the immune microenvironment of PCa and the related mechanisms are unknown. Here, we found a positive correlation between NDR1 and PD-L1 expression in PCa. NDR1 significantly inhibits CD8 + T cell infiltration and function, thereby promoting immune escape in prostate cancer.More importantly, NDR1 inhibition significantly enhanced CD8 + T cell activation, which enhanced the therapeutic effect of anti-PD-L1. Mechanistic studies revealed that NDR1 inhibits ubiquitination-mediated PD-L1 degradation via the deubiquitinase USP10, upregulates PD-L1, and promotes PCa immune escape. Thus, our study suggests a unique PD-L1 regulatory mechanism underlying PCa immunotherapy failure. The significance of NDR1 in PCa immune escape and its mechanism of action were clarified, and combined NDR1/PD-L1 inhibition was suggested as an approach to boost PCa immunotherapy effectiveness.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

Prognostic Significance of β-Catenin in Relation to the Tumor Immune Microenvironment in Oral Cancer

The aim of this study was to investigate the prognostic relevance of β-catenin expression in oral squamous cell carcinoma (OSCC) and to explore relationships with the tumor immune microenvironment. Expression of β-catenin and PD-L1, as well as lymphocyte and macrophage densities, were evaluated by immunohistochemistry in 125 OSCC patient specimens. Membranous β-catenin expression was detected in 102 (81.6%) and nuclear β-catenin in 2 (1.6%) tumors. There was an association between β-catenin expression, tumoral, and stromal CD8+ T-cell infiltration (TIL) and also the type of tumor immune microenvironment (TIME). Tumors harboring nuclear β-catenin were associated with a type II TIME (i.e., immune ignorance defined by a negative PD-L1 expression and low CD8+ TIL density), whereas tumors with membranous β-catenin expression were predominantly type IV (i.e., immune tolerance defined by negative PD-L1 and high CD8+ TIL density). Combined, but not individual, high stromal CD8+ TILs and membranous β-catenin expression was independently associated with better disease-specific survival (HR = 0.48, p = 0.019). Taken together, a combination of high stromal CD8+ T-cell infiltration and membranous β-catenin in the tumor emerges as an independent predictor of better survival in OSCC patients.

Role of β-catenin in PD-L1 expression of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a particular type of tumor connected to Epstein-Barr virus infection, genetic, and environmental factors. It is typically discovered late, with few therapeutic options and poor clinical outcomes. Cellular immune responses can be attenuated when programmed death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) are combined. Although PD-1 inhibitors have a different anti-tumor response rate than chemotherapy alone, they can nevertheless considerably outperform chemotherapy in patients with metastatic or recurrent NPC. The nuclear β-catenin can bind to the CD274 promoter region, promoting transcription and upregulating the expression of tumor-specific PD-L1. Separation of β-catenin from E-cadherin and translocation it into nucleus were both aided by β-catenin phosphorylates at the Tyr654 site. Its function in NPC and the expression of PD-L1 have not yet been investigated. This study investigated the predictive significance of PD-L1 and p-β-catenin^Tyr654 expressions in NPC. Our findings indicated that patients with distant metastases or poor prognoses exhibited higher levels of PD-L1 and p-β-catenin^Tyr654 expressions. According to Cox multivariate prognostic analysis, PD-L1 was also an effective indicator for predicting the survival status of patients with NPC. We subsequently demonstrated that PD-L1 transcription and protein production could be downregulated by targeting inhibition of the level of β-catenin in NPC cells. This is for developing the β-catenin or TCF4 inhibitor as a potential new option for immune checkpoint immunosuppression in NPC.

Targeting β-catenin and PD-L1 simultaneously by a racemic supramolecular peptide for the potent immunotherapy of hepatocellular carcinoma

Objective: The low clinical utility of immune checkpoint inhibitors (ICIs) against PD-1 or PD-L1 has recently been associated with the activation of the Wnt/β-catenin signaling pathway in hepatocellular carcinoma (HCC), which promotes tumor immune escape and resistance to anti-PD-1/PD-L1 therapy. Hence, we aimed to fabricate a supramolecular peptide which could target the Wnt/β-catenin signaling pathway coupled with ICIs blockage therapy for optimizing HCC immunotherapy. Methods: A racemic spherical supramolecular peptide termed sBBI&PDP nanoparticle was constructed by hierarchical self-assembly, comprising an L-enantiomeric peptide as an inhibitor of BCL9 and β-catenin (sBBI) and a D-enantiomeric peptide as an inhibitor of PD-1/PD-L1 (PDP). Results: sBBI&PDP nanoparticle potently suppressed the hyperactivated Wnt/β-catenin signaling pathway in vitro and in vivo, while blocking endogenous PD-L1 effectively. Furthermore, sBBI&PDP increased the infiltration and action of CD8+ T cells at tumor sites. Notably, compared with the original sBBI and commercial Anti-PD-L1 inhibitors, the designed sBBI&PDP showed stronger antitumor efficacy in an orthotopic homograft mice model of HCC and a PDX HCC model in Hu-PBMC-NSG mice. Moreover, sBBI&PDP possessed a favorable biosafety profile. Conclusion: The successful implementation of this strategy could revitalize ICIs blockage therapy and promote the discovery of artificial peptides for HCC immunotherapy.

PD-1 and PD-L1 Expression Levels as a Potential Biomarker of Chronic Rhinosinusitis and Head and Neck Cancers

Inflammation is an etiological factor of various chronic diseases contributing to more than 50% of worldwide deaths. In this study, we focus on the immunosuppressive role of the programmed death-1 (PD-1) receptor and its ligand (PD-L1) in inflammatory-related diseases, including chronic rhinosinusitis and head and neck cancers. The study included 304 participants. Of this number, 162 patients had chronic rhinosinusitis with nasal polyps (CRSwNP), 40 patients had head and neck cancer (HNC) and there were 102 healthy subjects. The expression level of the PD-1 and PD-L1 genes in the tissues of the study groups was measured by qPCR and Western blot methods. The associations between the age of the patients and the extent of disease and genes' expression were evaluated. The study showed a significantly higher mRNA expression of PD-1 and PD-L1 in the tissues of both the CRSwNP and HNC patient groups compared to the healthy group. The severity of CRSwNP significantly correlated with the mRNA expression of PD-1 and PD-L1. Similarly, the age of the NHC patients influenced PD-L1 expression. In addition, a significantly higher level of PD-L1 protein was noticed also for both the CRSwNP and HNC patient groups. The increased expression of PD-1 and PD-L1 may be a potential biomarker of inflammatory-related diseases, including chronic rhinosinusitis and head and neck cancers.

Potentiation of novel porphyrin based photodynamic therapy against colon cancer with low dose doxorubicin and elucidating the molecular signalling pathways responsible for relapse

Photodynamic therapy (PDT) is a promising non-invasive treatment modality for cancer and can be potentiated by combination with chemotherapy. Here, we combined PDT of novel porphyrin-based photosensitizers with low dose doxorubicin (Dox) to get maximum outcome. Dox potentiated and showed synergism with PDT under in vitro conditions on CT26.WT cells. The current colon cancer treatment strategies assure partial or even complete tumour regression but loco-regional relapse or distant metastasis is the major cause of death despite combination therapy. The spared cells after the treatment contribute to relapse and it is important to study their behaviour in host environment. Hence, we developed relapse models for PDT, Dox and combination treatments by transplanting respectively treated equal number of live cells to mice (n = 5) for tumour formation. Most of the treated cells lost tumour forming ability, but some treatment resistant cells developed tumours in few mice. These tumours served as relapse models and Western blot analysis of tumour samples provided clinically relevant information to delineate resistance strategies of individual as well as combination therapies at molecular level. Our results showed that low dose Dox helped in increasing the tumour inhibiting effect of PDT in combination therapy, but still there are indeed possibilities of relapse at later stages due to chemoresistance and immune suppression that may occur post-treatment. We observed that the combination therapy may also lead to the development of multidrug resistant (MDR) phenotype during relapse. Thus, this study provided clinically relevant information to further strengthen and improve PDT-drug combination therapy in order to avoid relapse and to treat cancer more effectively.

Anti-Lung Cancer Activities of 1,2,3-Triazole Curcumin Derivatives via Regulation of the MAPK/NF-κB/STAT3 Signaling Pathways

In this study, a series of curcumin derivatives containing 1,2,3-triazole were designed and synthesized, and their inhibitory activities against the proliferation of lung cancer cells were studied. Compound 5 k (3,4-dichlorobenzyltriazole methyl curcumin) had the best activity against A549 cells, with a half-maximal inhibitory concentration (IC₅₀ ) of 2.27 μM, which was approximately 10 times higher than that of the lead curcumin and higher than that of gefitinib (IC₅₀ =8.64 μM). Western blotting revealed that 5 k increased the phosphorylation levels of p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). Compound 5 k also promoted the expression of the inhibitor of nuclear factor-κB (IκBα) and decreased that of nuclear factor-κB (NF-κB), signal transducer and activator of transcription 3 (STAT3), and β-catenin. Therefore, 5 k suppresses A549 cell proliferation by activating the mitogen-activated protein kinases and suppressing NF-κB/STAT3 signaling pathways. So, 5 k can potentially be used for treating non-small cell lung cancer.

PD-1/PD-L1 Checkpoints and Resveratrol: A Controversial New Way for a Therapeutic Strategy

Simple Summary

Over the last decade, immunotherapies using antibodies targeting the programmed cell death 1 (PD-1) checkpoint or its ligand, programmed death ligand 1 (PD-L1), have emerged as promising therapeutic strategies against cancer. However, some current limitations include a relatively low rate of “responders”, the high cost of the treatment, and a rare risk of hyper-progression. Currently, the main challenge is, therefore, to improve these therapies, for instance, by using combined approaches. Here, we summarize the accumulating evidence that resveratrol (RSV) plays a role in the modulation of the PD-1/PD-L1 axis in cancer cells, suggesting the potential of therapeutic strategies combining RSV with PD-L1 or anti-PD-1 inhibitors. We then discuss the therapeutic potential of polyphenols such as RSV to be used in combination with PD-L1 or PD-1 inhibitors for the management of cancer patients.

Abstract

Immune checkpoints refer to a range of immunoregulatory molecules that modulate the immune response. For example, proteins expressed at the surface of T-cells (including PD-1 and CTLA-4) and their ligands (PD-L1 and B7-1/B7-2, respectively), expressed by cancer cells and antigen-presenting cells, are needed to prevent excessive immune responses. However, they dampen anti-tumor immunity by limiting T-cell activity, making them promising therapeutic targets in cancer. Although immunotherapies using checkpoint blocking/neutralizing antibodies targeting PD-L1 or PD-1 have proven their superiority over conventional chemotherapies or targeted therapies by enhancing T-cell-mediated anti-tumor immunity, some limitations have emerged. These include a relatively low rate of “responders” (<50%; irrespective of cancer type), the high cost of injections, and a rare risk of hyper-progression. For clinicians, the current challenge is thus to improve the existing therapies, potentially through combinatory approaches. Polyphenols such as resveratrol (RSV), a trihydroxystilbene found in various plants and an adjuvant in numerous nutraceuticals, have been proposed as potential therapeutic targets. Beyond its well-known pleiotropic effects, RSV affects PD-L1 and PD-1 expression as well as PD-L1 subcellular localization and post-translational modifications, which we review here. We also summarize the consequences of PD-1/PD-L1 signaling, the modalities of their blockade in the context of cancer, and the current status and limitations of these immunotherapies. Finally, we discuss their potential use in combination with chemotherapies, and, using RSV as a model, we propose polyphenols as adjuvants to enhance the efficacy of anti-PD-1/anti-PD-L1 immunotherapies.

Phospho-β-catenin expression in primary and metastatic melanomas and in tumor-free visceral tissues, and associations with expression of PD-L1 and PD-L2

β-catenin (βcat) is an important downstream effector in the Wnt signaling pathway and plays important roles in the development and progression of many cancers including melanoma. βcat expression is regulated by GSK-3β-mediated phosphorylation at positions 33, 37 and 41. In normal cells, phosphorylation at these sites triggers proteasomal degradation, which prevents accumulation of free cytoplasmic βcat. In cancer cells, stabilized β-catenin translocates into the nucleus, where it associates with TCF/Lef proteins to activate transcription of genes that promote tumorigenesis and metastasis, including PD-L1. It has been suggested that nuclear phospho-βcat (pβcat) staining may be diagnostically useful in differentiating primary from metastatic melanoma. Also, a pβcat peptide (residues 30-39, with only S33 phosphorylated) is naturally presented by melanoma cells as a T-cell target. We evaluated expression of pS33-βcat in primary and metastatic melanomas by immunohistochemistry and found its expression varied widely but was most commonly cytoplasmic. Nuclear staining was identified in only 18% of metastatic melanomas. Staining with antibodies to pS33-βcat and pS33/37/T41-βcat was most intense in mitotic melanoma cells; however, pS33-βcat intensity was not significantly associated with AJCC stage, tumor location, BRAF mutation status, or immune infiltrates. Yet, PD-L1 and PD-L2 expression by tumor cells were significantly higher in tumors with high pS33-βcat expression. The low rate of nuclear pS33-βcat expression suggests that pS33-βcat may have limited utility for identifying metastatic melanomas. However, high expression in dividing cells and strong associations with PD-L1 and PD-L2 expression may inform future personalized therapies for tumors with high pS33-βcat expression.

Polyphenols Modulating Effects of PD-L1/PD-1 Checkpoint and EMT-Mediated PD-L1 Overexpression in Breast Cancer

Investigating dietary polyphenolic compounds as antitumor agents are rising due to the growing evidence of the close association between immunity and cancer. Cancer cells elude immune surveillance for enhancing their progression and metastasis utilizing various mechanisms. These mechanisms include the upregulation of programmed death-ligand 1 (PD-L1) expression and Epithelial-to-Mesenchymal Transition (EMT) cell phenotype activation. In addition to its role in stimulating normal embryonic development, EMT has been identified as a critical driver in various aspects of cancer pathology, including carcinogenesis, metastasis, and drug resistance. Furthermore, EMT conversion to another phenotype, Mesenchymal-to-Epithelial Transition (MET), is crucial in developing cancer metastasis. A central mechanism in the upregulation of PD-L1 expression in various cancer types is EMT signaling activation. In breast cancer (BC) cells, the upregulated level of PD-L1 has become a critical target in cancer therapy. Various signal transduction pathways are involved in EMT-mediated PD-L1 checkpoint overexpression. Three main groups are considered potential targets in EMT development; the effectors (E-cadherin and Vimentin), the regulators (Zeb, Twist, and Snail), and the inducers that include members of the transforming growth factor-beta (TGF-β). Meanwhile, the correlation between consuming flavonoid-rich food and the lower risk of cancers has been demonstrated. In BC, polyphenols were found to downregulate PD-L1 expression. This review highlights the effects of polyphenols on the EMT process by inhibiting mesenchymal proteins and upregulating the epithelial phenotype. This multifunctional mechanism could hold promises in the prevention and treating breast cancer.

Wnt Inhibition Sensitizes PD-L1 Blockade Therapy by Overcoming Bone Marrow-Derived Myofibroblasts-Mediated Immune Resistance in Tumors

Cancer-associated fibroblasts (CAFs) has been recognized as one cause of tumor resistance to immune checkpoint blockade therapy, but the underlying mechanisms still remain elusive. In the present study, a bone marrow-derived CAF (BMF) -rich tumor model is successfully established by subcutaneously mixed inoculation of BMFs and tumor cells into mice and the BMF-mixed tumor xenografts are demonstrated to be resistant to anti-PD-L1 antibody immunotherapy compared to the mere tumor xenografts. In vitro assays via the co-culture system of BMFs and tumor cells indicate that the co-cultured BMFs are induced to overexpress PD-L1, while there is no such a phenomenon in the co-cultured cancer cells. The further knock-out of PD-L1 in BMFs rescues the sensitivity of BMF-mixed tumor xenografts to PD-L1 blockade therapy. Mechanistically, via the microarray assay, we identify that the upregulation of PD-L1 in BMFs stimulated by cancer cells is medicated by the activation of the Wnt/β-catenin signaling pathway in BMFs. Moreover, the administration of Wnt/β-catenin signaling inhibitors, including XAV-939 and Wnt-C59, distinctly inhibits the upregulation of PD-L1 expression in the co-cultured BMFs. The further combination administration of XAV-939 significantly potentiates the therapeutic outcome of PD-L1 blockade therapy in BMF-mixed tumors. In summary, our study demonstrates that Wnt inhibition augments PD-L1 blockade efficacy by overcoming BMF-mediated immunotherapy resistance.