LPS promotes the expression of PD-L1 in gastric cancer cells through NF-κB activation

The role of the immunosuppressive PD-1/PD-L1 checkpoint pathway in the aging process and age-related diseases

The accumulation of senescent cells within tissues is a hallmark of the aging process. Senescent cells are also commonly present in many age-related diseases and in the cancer microenvironment. The escape of abnormal cells from immune surveillance indicates that there is some defect in the function of cytotoxic immune cells, e.g., CD8+ T cells and natural killer (NK) cells. Recent studies have revealed that the expression of programmed death-ligand 1 (PD-L1) protein is abundantly increased in senescent cells. An increase in the amount of PD-L1 protein protects senescent cells from clearance by the PD-1 checkpoint receptor in cytotoxic immune cells. In fact, the activation of the PD-1 receptor suppresses the cytotoxic properties of CD8+ T and NK cells, promoting a state of immunosenescence. The inhibitory PD-1/PD-L1 checkpoint pathway acts in cooperation with immunosuppressive cells; for example, activation of PD-1 receptor can enhance the differentiation of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), and M2 macrophages, whereas the cytokines secreted by immunosuppressive cells stimulate the expression of the immunosuppressive PD-L1 protein. Interestingly, many signaling pathways known to promote cellular senescence and the aging process are crucial stimulators of the expression of PD-L1 protein, e.g., epigenetic regulation, inflammatory mediators, mTOR-related signaling, cGAS-STING pathway, and AhR signaling. It seems that the inhibitory PD-1/PD-L1 immune checkpoint axis has a crucial role in the accumulation of senescent cells and thus it promotes the aging process in tissues. Thus, the blockade of the PD-1/PD-L1 checkpoint signaling might be a potential anti-aging senolytic therapy. KEY MESSAGES: Senescent cells accumulate within tissues during aging and age-related diseases. Senescent cells are able to escape immune surveillance by cytotoxic immune cells. Expression of programmed death-ligand 1 (PD-L1) markedly increases in senescent cells. Age-related signaling stimulates the expression of PD-L1 protein in senescent cells. Inhibitory PD-1/PD-L1 checkpoint pathway suppresses clearance of senescent cells.

Cross-Talks between Raf Kinase Inhibitor Protein and Programmed Cell Death Ligand 1 Expressions in Cancer: Role in Immune Evasion and Therapeutic Implications

Innovations in cancer immunotherapy have resulted in the development of several novel immunotherapeutic strategies that can disrupt immunosuppression. One key advancement lies in immune checkpoint inhibitors (ICIs), which have shown significant clinical efficacy and increased survival rates in patients with various therapy-resistant cancers. This immune intervention consists of monoclonal antibodies directed against inhibitory receptors (e.g., PD-1) on cytotoxic CD8 T cells or against corresponding ligands (e.g., PD-L1/PD-L2) overexpressed on cancer cells and other cells in the tumor microenvironment (TME). However, not all cancer cells respond-there are still poor clinical responses, immune-related adverse effects, adaptive resistance, and vulnerability to ICIs in a subset of patients with cancer. This challenge showcases the heterogeneity of cancer, emphasizing the existence of additional immunoregulatory mechanisms in many patients. Therefore, it is essential to investigate PD-L1's interaction with other oncogenic genes and pathways to further advance targeted therapies and address resistance mechanisms. Accordingly, our aim was to investigate the mechanisms governing PD-L1 expression in tumor cells, given its correlation with immune evasion, to uncover novel mechanisms for decreasing PD-L1 expression and restoring anti-tumor immune responses. Numerous studies have demonstrated that the upregulation of Raf Kinase Inhibitor Protein (RKIP) in many cancers contributes to the suppression of key hyperactive pathways observed in malignant cells, alongside its broadening involvement in immune responses and the modulation of the TME. We, therefore, hypothesized that the role of PD-L1 in cancer immune surveillance may be inversely correlated with the low expression level of the tumor suppressor Raf Kinase Inhibitor Protein (RKIP) expression in cancer cells. This hypothesis was investigated and we found several signaling cross-talk pathways between the regulations of both RKIP and PD-L1 expressions. These pathways and regulatory factors include the MAPK and JAK/STAT pathways, GSK3β, cytokines IFN-γ and IL-1β, Sox2, and transcription factors YY1 and NFκB. The pathways that upregulated PD-L1 were inhibitory for RKIP expression and vice versa. Bioinformatic analyses in various human cancers demonstrated the inverse relationship between PD-L1 and RKIP expressions and their prognostic roles. Therefore, we suspect that the direct upregulation of RKIP and/or the use of targeted RKIP inducers in combination with ICIs could result in a more targeted anti-tumor immune response-addressing the therapeutic challenges related to PD-1/PD-L1 monotherapy alone.

All eyes on Eya: A unique transcriptional co-activator and phosphatase in cancer

The Eya family of proteins (consisting of Eyas1-4 in mammals) play vital roles in embryogenesis by regulating processes such as proliferation, migration/invasion, cellular survival and pluripotency/plasticity of epithelial and mesenchymal states. Eya proteins carry out such diverse functions through a unique combination of transcriptional co-factor, Tyr phosphatase, and PP2A/B55α-mediated Ser/Thr phosphatase activities. Since their initial discovery, re-expression of Eyas has been observed in numerous tumor types, where they are known to promote tumor progression through a combination of their transcriptional and enzymatic activities. Eya proteins thus reinstate developmental processes during malignancy and represent a compelling class of therapeutic targets for inhibiting tumor progression.

Infiltration to infection: key virulence players of Helicobacter pylori pathogenicity

PURPOSE

This study aims to comprehensively review the multifaceted factors underlying the successful colonization and infection process of Helicobacter pylori (H. pylori), a prominent Gram-negative pathogen in humans. The focus is on elucidating the functions, mechanisms, genetic regulation, and potential cross-interactions of these elements.

METHODS

Employing a literature review approach, this study examines the intricate interactions between H. pylori and its host. It delves into virulence factors like VacA, CagA, DupA, Urease, along with phase variable genes, such as babA, babC, hopZ, etc., giving insights about the bacterial perspective of the infection The association of these factors with the infection has also been added in the form of statistical data via Funnel and Forest plots, citing the potential of the virulence and also adding an aspect of geographical biasness to the virulence factors. The biochemical characteristics and clinical relevance of these factors and their effects on host cells are individually examined, both comprehensively and statistically.

RESULTS

H. pylori is a Gram-negative, spiral bacterium that successfully colonises the stomach of more than half of the world's population, causing peptic ulcers, gastric cancer, MALT lymphoma, and other gastro-duodenal disorders. The clinical outcomes of H. pylori infection are influenced by a complex interplay between virulence factors and phase variable genes produced by the infecting strain and the host genetic background. A meta-analysis of the prevalence of all the major virulence factors has also been appended.

CONCLUSION

This study illuminates the diverse elements contributing to H. pylori's colonization and infection. The interplay between virulence factors, phase variable genes, and host genetics determines the outcome of the infection. Despite biochemical insights into many factors, their comprehensive regulation remains an understudied area. By offering a panoramic view of these factors and their functions, this study enhances understanding of the bacterium's perspective, i.e. H. pylori's journey from infiltration to successful establishment within the host's stomach.

Roles of PD-L1 in human adipose-derived mesenchymal stem cells under inflammatory microenvironment

Mesenchymal stem cells (MSCs) display unique homing and immunosuppression features which make them promising candidates for cell therapy in inflammatory disorders. It is known that C-X-C chemokine receptor type 4 (CXCR4, also known as CD184) is a critical receptor implicated in MSCs migration, and the protein programmed death ligand-1 (PD-L1) is involved in MSC's immunosuppression. However, it remains unclear how the molecular mechanisms regulate PD-L1 expression for migration and immunosuppression of MSCs under the inflammatory microenvironment. In this article, we used the human adipose-derived mesenchymal stem cells (hADMSCs) treated with lipopolysaccharide (LPS) as an in vitro inflammatory model to explore the roles of PD-L1 on the migration and immunosuppression of MSC. Our results demonstrate that in hADMSCs, LPS significantly increased PD-L1 expression, which mediated the migration of the LPS-treated hADMSCs via CXCR4. In addition, we found that the increased PD-L1 expression in the LPS-treated hADMSCs inhibited B cell proliferation and immunoglobulin G secretion through nuclear factor-κB. Our study suggests that the PD-L1 plays critical roles in the homing and immunosuppression of MSCs which are a promising cell therapy to treat inflammatory diseases.

Targeting the NF-κB pathway as a potential regulator of immune checkpoints in cancer immunotherapy

Advances in cancer immunotherapy over the last decade have led to the development of several agents that affect immune checkpoints. Inhibitory receptors expressed on T cells that negatively regulate the immune response include cytotoxic T‑lymphocyte antigen 4 (CTLA4) and programmed cell death protein 1 (PD1), which have been studied more than similar receptors. Inhibition of these proteins and other immune checkpoints can stimulate the immune system to attack cancer cells, and prevent the tumor from escaping the immune response. However, the administration of anti-PD1 and anti-CTLA4 antibodies has been associated with adverse inflammatory responses similar to autoimmune diseases. The current review discussed the role of the NF-κB pathway as a tumor promoter, and how it can govern inflammatory responses and affect various immune checkpoints. More precise knowledge about the communication between immune checkpoints and NF-κB pathways could increase the effectiveness of immunotherapy and reduce the adverse effects of checkpoint inhibitor therapy.

Identifying a locus in super-enhancer and its resident NFE2L1/MAFG as transcriptional factors that drive PD-L1 expression and immune evasion

Although the transcriptional regulation of the programmed death ligand 1 (PD-L1) promoter has been extensively studied, the transcription factor residing in the PD-L1 super-enhancer has not been comprehensively explored. Through saturated CRISPR-Cas9 screening of the core region of the PD-L1 super-enhancer, we have identified a crucial genetic locus, referred to as locus 22, which is essential for PD-L1 expression. Locus 22 is a potential binding site for NFE2:MAF transcription factors. Although genetic silencing of NRF2 (NFE2L2) did not result in a reduction of PD-L1 expression, further analysis reveals that MAFG and NFE2L1 (NRF1) play a critical role in the expression of PD-L1. Importantly, lipopolysaccharides (LPS) as the major component of intratumoral bacteria could greatly induce PD-L1 expression, which is dependent on the PD-L1 super-enhancer, locus 22, and NFE2L1/MAFG. Mechanistically, genetic modification of locus 22 and silencing of MAFG greatly reduce BRD4 binding and loop formation but have minimal effects on H3K27Ac modification. Unlike control cells, cells with genetic modification of locus 22 and silencing of NFE2L1/MAFG failed to escape T cell-mediated killing. In breast cancer, the expression of MAFG is positively correlated with the expression of PD-L1. Taken together, our findings demonstrate the critical role of locus 22 and its associated transcription factor NFE2L1/MAFG in super-enhancer- and LPS-induced PD-L1 expression. Our findings provide new insight into understanding the regulation of PD-L1 transcription and intratumoral bacteria-mediated immune evasion.

NLRP3 and cancer: Pathogenesis and therapeutic opportunities

More than a decade ago IL-1 blockade was suggested as an add-on therapy for the treatment of cancer. This proposal was based on the overall safety record of anti-IL-1 biologics and the anti-tumor properties of IL-1 blockade in animal models of cancer. Today, a new frontier in IL-1 activity regulation has developed with several orally active NLRP3 inhibitors currently in clinical trials, including cancer. Despite an increasing body of evidence suggesting a role of NLRP3 and IL-1-mediated inflammation driving cancer initiation, immunosuppression, growth, and metastasis, NLRP3 activation in cancer remains controversial. In this review, we discuss the recent advances in the understanding of NLRP3 activation in cancer. Further, we discuss the current opportunities for NLRP3 inhibition in cancer intervention with novel small molecules.

Sulforaphane Reduces the Chronic Inflammatory Immune Response of Human Dendritic Cells

BACKGROUND

Sulforaphane (SFN) is an isothiocyanate of vegetable origin with potent antioxidant and immunomodulatory properties. The characterization of its pleiotropic activity in human dendritic cells (DCs) is poorly summarized. The aim of this work was to study the immunomodulatory power of SFN in response to an inflammatory microenvironment on human monocyte-derived DCs (moDCs).

METHODS

We studied the immunological response induced by SFN. Apoptosis and autophagy assays were performed using flow cytometry on moDCs and a cancer cell line (THP-1). These included moDC maturation, lymphocyte proliferation and cytokine production under different experimental conditions. We investigated whether these results were associated with an inflammatory microenvironment induced by lipopolysaccharides (LPSs).

RESULTS

Our results demonstrated that SFN could interact with moDCs, significantly reducing the autophagy process and enhancing apoptosis similarly to cancer cell line THP-1 cells in a chronic inflammatory microenvironment. Under chronic inflammation, SFN modulated the phenotypical characteristics of moDCs, reducing the expression of all markers (CD80, CD83, CD86, HLA-DR and PD-L1). SFN significantly reduced the Th2 proliferative response, with a decrease in the IL-9 and IL-13 levels. Although we did not observe any changes in the regulatory proliferative response, we noted an increase in the IL-10 levels.

CONCLUSIONS

These findings demonstrate that SFN exerts protective effects against LPS-induced inflammation via the modulation of moDCs/T cells towards a regulatory profile. SFN may be a potential candidate for the treatment of pathologies with an inflammatory profile.

Role of regulation of PD-1 and PD-L1 expression in sepsis

Long term immunosuppression is problematic during sepsis. The PD-1 and PD-L1 immune checkpoint proteins have potent immunosuppressive functions. Recent studies have revealed several features of PD-1 and PD-L1 and their roles in sepsis. Here, we summarize the overall findings of PD-1 and PD-L1 by first reviewing the biological features of PD-1 and PD-L1 and then discussing the mechanisms that control the expression of PD-1 and PD-L1. We then review the functions of PD-1 and PD-L1 in physiological settings and further discuss PD-1 and PD-L1 in sepsis, including their involvement in several sepsis-related processes and their potential therapeutic relevance in sepsis. In general, PD-1 and PD-L1 have critical roles in sepsis, indicating that their regulation may be a potential therapeutic target for sepsis.

Gastric immune homeostasis imbalance: An important factor in the development of gastric mucosal diseases

The gastric mucosal immune system is a unique immune organ independent of systemic immunity that not only maintains nutrient absorption but also plays a role in resisting the external environment. Gastric mucosal immune disorder leads to a series of gastric mucosal diseases, including autoimmune gastritis (AIG)-related diseases, Helicobacter pylori (H. pylori)-induced diseases, and various types of gastric cancer (GC). Therefore, understanding the role of gastric mucosal immune homeostasis in gastric mucosal protection and the relationship between mucosal immunity and gastric mucosal diseases is very important. This review focuses on the protective effect of gastric mucosal immune homeostasis on the gastric mucosa, as well as multiple gastric mucosal diseases caused by gastric immune disorders. We hope to offer new prospects for the prevention and treatment of gastric mucosal diseases.

Beyond Cancer: Regulation and Function of PD-L1 in Health and Immune-Related Diseases

Programmed Cell Death 1 Ligand 1 (PD-L1, CD274, B7-H1) is a transmembrane protein which is strongly involved in immune modulation, serving as checkpoint regulator. Interaction with its receptor, Programmed Cell Death Protein 1 (PD-1), induces an immune-suppressive signal, which modulates the activity of T cells and other effector cells. This mediates peripheral tolerance and contributes to tumor immune escape. PD-L1 became famous due to its deployment in cancer therapy, where blockage of PD-L1 with the help of therapeutic antagonistic antibodies achieved impressive clinical responses by reactivating effector cell functions against tumor cells. Therefore, in the past, the focus has been placed on PD-L1 expression and its function in various malignant cells, whereas its role in healthy tissue and diseases apart from cancer remained largely neglected. In this review, we summarize the function of PD-L1 in non-cancerous cells, outlining its discovery and origin, as well as its involvement in different cellular and immune-related processes. We provide an overview of transcriptional and translational regulation, and expression patterns of PD-L1 in different cells and organs, and illuminate the involvement of PD-L1 in different autoimmune diseases as well as in the context of transplantation and pregnancy.

Effects of helicobacter pylori on tumor microenvironment and immunotherapy responses

Helicobacter pylori is closely associated with gastric cancer. During persistent infection, Helicobacter pylori can form a microenvironment in gastric mucosa which facilitates the survival and colony formation of Helicobacter pylori. Tumor stromal cells are involved in this process, including tumor-associated macrophages, mesenchymal stem cells, cancer-associated fibroblasts, and myeloid-derived suppressor cells, and so on. The immune checkpoints are also regulated by Helicobacter pylori infection. Helicobacter pylori virulence factors can also act as immunogens or adjuvants to elicit or enhance immune responses, indicating their potential applications in vaccine development and tumor immunotherapy. This review highlights the effects of Helicobacter pylori on the immune microenvironment and its potential roles in tumor immunotherapy responses.

NCX1 coupled with TRPC1 to promote gastric cancer via Ca2+/AKT/β-catenin pathway

Plasma membrane Na⁺/Ca²⁺ exchanger 1 (NCX1) is a bidirectional ion transporter to operate in Ca²⁺ entry or exit modes, and TRPC1 is Ca²⁺-permeable channel. Both NCX1 and TRPC1 play critical roles in maintaining cytosolic free Ca²⁺ ([Ca²⁺]_cyt) homeostasis in mammalian cells. Although either TRPC1 channel or Ca²⁺ entry mode of NCX1 is implicated in some tumorigenesis, it has not been explored if a coordination of NCX1 and TRPC1 involves in the pathogenesis of H. pylori-associated human gastric cancer (GC). Here we found the protein expression of NCX1 was significantly enhanced in human GC specimens, which correlated with tumor progression and poor survival in GC patients. TRPC1 and NCX1 were parallelly enhanced, co-localized and bound in human GC cells. By a functional coupling, TRPC1 drives NCX1 to the Ca²⁺ entry mode, raising [Ca²⁺]_cyt in GC cells. Moreover, CaCl₂, H. pylori and their virulence factors all enhanced expressions and activities of NCX1 and TRPC1, and evoked aberrant Ca²⁺ entry to promote proliferation, migration, and invasion of GC cells through AKT/β-catenin pathway. Tumor growth and metastasis also depended on the enhanced expression of NCX1 in subcutaneously xenografted GC mouse model. Overall, our findings indicate that TRPC1/NCX1 coupling may promote H. pylori-associated GC through the Ca²⁺/AKT/β-catenin pathway. Since the Ca²⁺ exit mode and the Ca²⁺ entry mode of NCX1 play different roles under mostly physiological and pathological conditions respectively, targeting TRPC1/NCX1 coupling could be a novel strategy for selectively blocking Ca²⁺ entry mode to potentially treat digestive cancer with less side effect.

Unveiling the Molecular Mechanisms Driving the Capsaicin-Induced Immunomodulatory Effects on PD-L1 Expression in Bladder and Renal Cancer Cell Lines

Simple Summary

Over time, capsaicin (CPS) has been considered both a potential anti-cancer and pro-cancer molecule. Hence, the diversity of CPS functioning has already been established. Now, exploration of its application with immunotherapies might open up a new avenue in cancer therapy. Herein, the application of CPS as an immunoadjuvant to overcome the tumor’s immune-escaping mechanisms or to increase immune checkpoint therapy has been approached. In bladder cancer, the interaction of CPS with its receptor TRPV1 increases PD-L1 expression, promoting a tumorigenic effect and also providing a target for anti-PD-1/PD-L1 immunotherapy. On the contrary, in renal cell carcinoma, CPS downregulates PD-L1 expression in a TRPV1-independent manner, suggesting a potential application of CPS as an immune-adjuvant in this type of cancer.

Abstract

The blockade of the PD-L1/PD-1 immune checkpoint has promising efficacy in cancer treatment. However, few patients with bladder cancer (BC) or renal cell carcinoma (RCC) respond to this approach. Thus, it is important to implement a strategy to stimulate the immune anti-tumor response. In this scenario, our study evaluated the effects of a low capsaicin (CPS) dose in BC and RCC cell lines. Western blot, qRT-PCR and confocal microscopy were used to assess PD-L1 mRNA and protein expression. Alterations to the cellular oxidative status and changes to the antioxidant NME4 levels, mRNA modulation of cytokines, growth factors, transcriptional factors and oncogene, and the activation of Stat1/Stat3 pathways were examined using Western blot, cytofluorimetry and qRT-PCR profiling assays. In BC, CPS triggers an altered stress oxidative-mediated DNA double-strand break response and increases the PD-L1 expression. On the contrary, in RCC, CPS, by stimulating an efficient DNA damage repair response, thus triggering protein carbonylation, reduces the PD-L1 expression. Overall, our results show that CPS mediates a multi-faceted approach. In modulating PD-L1 expression, there is a rationale for CPS exploitation as a stimulus that increases BC cells’ response to immunotherapy or as an immune adjuvant to improve the efficacy of the conventional therapy in RCC patients.

Dysbiosis of skin microbiome and gut microbiome in melanoma progression

Background

The microbiome alterations are associated with cancer growth and may influence the immune system and response to therapy. Particularly, the gut microbiome has been recently shown to modulate response to melanoma immunotherapy. However, the role of the skin microbiome has not been well explored in the skin tumour microenvironment and the link between the gut microbiome and skin microbiome has not been investigated in melanoma progression. Therefore, the aim of the present study was to examine associations between dysbiosis in the skin and gut microbiome and the melanoma growth using MeLiM porcine model of melanoma progression and spontaneous regression.

Results

Parallel analysis of cutaneous microbiota and faecal microbiota of the same individuals was performed in 8 to 12 weeks old MeLiM piglets. The bacterial composition of samples was analysed by high throughput sequencing of the V4-V5 region of the 16S rRNA gene. A significant difference in microbiome diversity and richness between melanoma tissue and healthy skin and between the faecal microbiome of MeLiM piglets and control piglets were observed. Both Principal Coordinate Analysis and Non-metric multidimensional scaling revealed dissimilarities between different bacterial communities. Linear discriminant analysis effect size at the genus level determined different potential biomarkers in multiple bacterial communities. Lactobacillus, Clostridium sensu stricto 1 and Corynebacterium 1 were the most discriminately higher genera in the healthy skin microbiome, while Fusobacterium, Trueperella, Staphylococcus, Streptococcus and Bacteroides were discriminately abundant in melanoma tissue microbiome. Bacteroides, Fusobacterium and Escherichia-Shigella were associated with the faecal microbiota of MeLiM piglets. Potential functional pathways analysis based on the KEGG database indicated significant differences in the predicted profile metabolisms between the healthy skin microbiome and melanoma tissue microbiome. The faecal microbiome of MeLiM piglets was enriched by genes related to membrane transports pathways allowing for the increase of intestinal permeability and alteration of the intestinal mucosal barrier.

Conclusion

The associations between melanoma progression and dysbiosis in the skin microbiome as well as dysbiosis in the gut microbiome were identified. Results provide promising information for further studies on the local skin and gut microbiome involvement in melanoma progression and may support the development of new therapeutic approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02458-5.

RelB upregulates PD-L1 and exacerbates prostate cancer immune evasion

Background

The interaction between programmed death receptor (PD-1) and its ligand (PD-L1) is essential for suppressing activated T-lymphocytes. However, the precise mechanisms underlying PD-L1 overexpression in tumours have yet to be fully elucidated. Here, we describe that RelB participates in the immune evasion of prostate cancer (PCa) via cis/trans transcriptional upregulation of PD-L1.

Methods

Based on transcriptome results, RelB was manipulated in multiple human and murine PCa cell lines. Activated CD4⁺ and CD8⁺ T cells were cocultured with PCa cells with different levels of RelB to examine the effect of tumourous RelB on T cell immunity. Male mice were injected with murine PCa cells to validate the effect of RelB on the PD-1/PD-L1-mediated immune checkpoint using both tumour growth and metastatic experimental models.

Results

PD-L1 is uniquely expressed at a high level in PCa with high constitutive RelB and correlates with the patients’ Gleason scores. Indeed, a high level of PD-L1 is associated with RelB nuclear translocation in AR-negative aggressive PCa cells. Conversely, the silencing of RelB in advanced PCa cells resulted in reduced PD-L1 expression and enhanced susceptibility of PCa cells to the T cell immune response in vitro and in vivo. Mechanistically, a proximal NF-κB enhancer element was identified in the core promoter region of the human CD274 gene, which is responsible for RelB-mediated PD-L1 transcriptional activation. This finding provides an informative insight into immune checkpoint blockade by administering RelB within the tumour microenvironment.

Conclusion

This study deciphers the molecular mechanism by which tumourous RelB contributes to immune evasion by inhibiting T cell immunity via the amplification of the PD-L1/PD-1-mediated immune checkpoint.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02243-2.

Chitosan oligosaccharide regulates AMPK and STAT1 pathways synergistically to mediate PD-L1 expression for cancer chemoimmunotherapy

After regular chemotherapy, the expression of programmed cell death ligand 1 (PD-L1) in almost all kinds of cancers is significantly increased, leading to reduced efficacy of T cell mediated immune killing in tumors. To solve this, a lot of PD-L1 antibodies were produced and used, but their high cost and serious toxic side effects still limit its usage. Recently, small molecule compounds that could effectively regulate PD-L1 expression possess the edges to solve the problems of PD-L1 antibodies. Chitosan oligosaccharide (COS), a biomaterial derived from the N-deacetylation product of chitin, has a broad spectrum of biological activities in treating tumors. However, the mechanism of its anti-cancer effect is still not well understood. Here, for the first time, we clearly identified that COS could inhibit the upregulated PD-L1 expression induced by interferon γ (IFN-γ) in various tumors via the AMPK activation and STAT1 inhibition. Besides, COS itself significantly restricted the growth of CT26 tumors by enhancing the T cell infiltration in tumors. Furthermore, we observed that combining COS with Gemcitabine (GEM), one of the typical chemotherapeutic drugs, leaded to a more remarkable tumor remission. Therefore, it was demonstrated that COS could be used as a useful way to improve the efficacy of existing chemotherapies by effective PD-L1 downregulation.

Potential Role of CXCL13/CXCR5 Signaling in Immune Checkpoint Inhibitor Treatment in Cancer

Simple Summary

Immunotherapy is currently the backbone of new drug treatments for many cancer patients. CXC chemokine ligand 13 (CXCL13) is an important factor involved in recruiting immune cells that express CXC chemokine receptor type 5 (CXCR5) in the tumor microenvironment and serves as a key molecular determinant of tertiary lymphoid structure (TLS) formation. An increasing number of studies have identified the influence of CXCL13 on prognosis in patients with cancer, regardless of the use of immunotherapy treatment. However, no comprehensive reviews of the role of CXCL13 in cancer immunotherapy have been published to date. This review aims to provide an overview of the CXCL13/CXCR5 signaling axis to summarize its mechanisms of action in cancer cells and lymphocytes, in addition to effects on immunity and cancer pathobiology, and its potential as a biomarker for the response to cancer immunotherapy.

Abstract

Immune checkpoint inhibitors (ICIs), including antibodies that target programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), or cytotoxic T lymphocyte antigen 4 (CTLA4), represent some of the most important breakthroughs in new drug development for oncology therapy from the past decade. CXC chemokine ligand 13 (CXCL13) exclusively binds CXC chemokine receptor type 5 (CXCR5), which plays a critical role in immune cell recruitment and activation and the regulation of the adaptive immune response. CXCL13 is a key molecular determinant of the formation of tertiary lymphoid structures (TLSs), which are organized aggregates of T, B, and dendritic cells that participate in the adaptive antitumor immune response. CXCL13 may also serve as a prognostic and predictive factor, and the role played by CXCL13 in some ICI-responsive tumor types has gained intense interest. This review discusses how CXCL13/CXCR5 signaling modulates cancer and immune cells to promote lymphocyte infiltration, activation by tumor antigens, and differentiation to increase the antitumor immune response. We also summarize recent preclinical and clinical evidence regarding the ICI-therapeutic implications of targeting the CXCL13/CXCR5 axis and discuss the potential role of this signaling pathway in cancer immunotherapy.

High concentration of Dezocine induces immune escape of lung cancer and promotes glucose metabolism through up-regulating PD-L1 and activating NF-κB pathway

BACKGROUND

Dezocine is an opioid analgesic that can affect the immune system. Here, we explored the synergy of high concentration of Dezocine and Programmed death-ligand 1 (PD-L1) with regards to immune escape and glucose metabolism in lung cancer (LC).

METHODS

PD-L1 level in human LC cell lines was determined and the influence of Dezocine at different concentrations for the proliferation of LC cells was identified. Next, LC cells were transfected to alter PD-L1 level, and exposed to Dezocine at 8 μg/mL to explore their effects on cell proliferation, production of interferon-γ (IFN-γ), contents of glucose, lactate and NADPH/NADP+ and activation of the nuclear factor-κB (NF-κB) pathway.

RESULTS

PD-L1 level was increased in LC cells and Dezocine (8 μg/mL) impaired the proliferation of LC cells. Down-regulating PD-L1 inhibited cell proliferation, enhanced production of IFN-γ and reduced the contents of glucose, lactate and NADPH/NADP+ while up-regulating PD-L1 caused the opposite results. Dezocine (8 μg/mL) induced immune escape and glucose metabolism in LC, and Dezocine-induced effects were reversed by down-regulating PD-L1. Dezocine (8 μg/mL) up-regulated PD-L1 by activating the NF-κB pathway.

CONCLUSION

Dezocine at 8 μg/mL promotes immune escape and glucose metabolism in LC through up-regulating PD-L1 and activating the NF-κB pathway.

Role of the PD-1/PD-L1 Signaling in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis: Recent Insights and Future Directions

Multiple sclerosis (MS) is an autoimmunity-related chronic demyelination disease of the central nervous system (CNS), causing young disability. Currently, highly specific immunotherapies for MS are still lacking. Programmed cell death 1 (PD-1) is an immunosuppressive co-stimulatory molecule, which is expressed on activated T lymphocytes, B lymphocytes, natural killer cells, and other immune cells. PD-L1, the ligand of PD-1, is expressed on T lymphocytes, B lymphocytes, dendritic cells, and macrophages. PD-1/PD-L1 delivers negative regulatory signals to immune cells, maintaining immune tolerance and inhibiting autoimmunity. This review comprehensively summarizes current insights into the role of PD-1/PD-L1 signaling in MS and its animal model experimental autoimmune encephalomyelitis (EAE). The potentiality of PD-1/PD-L1 as biomarkers or therapeutic targets for MS will also be discussed.

Fusobacterium nucleatum enhances the efficacy of PD-L1 blockade in colorectal cancer

Given that only a subset of patients with colorectal cancer (CRC) benefit from immune checkpoint therapy, efforts are ongoing to identify markers that predict immunotherapeutic response. Increasing evidence suggests that microbes influence the efficacy of cancer therapies. Fusobacterium nucleatum induces different immune responses in CRC with different microsatellite-instability (MSI) statuses. Here, we investigated the effect of F. nucleatum on anti-PD-L1 therapy in CRC. We found that high F. nucleatum levels correlate with improved therapeutic responses to PD-1 blockade in patients with CRC. Additionally, F. nucleatum enhanced the antitumor effects of PD-L1 blockade on CRC in mice and prolonged survival. Combining F. nucleatum supplementation with immunotherapy rescued the therapeutic effects of PD-L1 blockade. Furthermore, F. nucleatum induced PD-L1 expression by activating STING signaling and increased the accumulation of interferon-gamma (IFN-γ)+ CD8+ tumor-infiltrating lymphocytes (TILs) during treatment with PD-L1 blockade, thereby augmenting tumor sensitivity to PD-L1 blockade. Finally, patient-derived organoid models demonstrated that increased F. nucleatum levels correlated with an improved therapeutic response to PD-L1 blockade. These findings suggest that F. nucleatum may modulate immune checkpoint therapy for CRC.

LINC01123 is associated with prognosis of oral squamous cell carcinoma and involved in tumor progression by sponging miR-34a-5p

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is a malignant tumor. This study aimed to investigate the role of a long noncoding RNA (lncRNA), LINC01123, in OSCC prognosis and progression and to explore the underlying mechanisms.

STUDY DESIGN

OSCC tissues were collected from 102 patients, and 4 OSCC cell lines were analyzed. The expression levels of LINC01123 and miR-34a-5p were estimated using quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) and Transwell assays were used to assess the proliferation, migration, and invasion of OSCC cells. Kaplan-Meier survival analysis was used to analyze the prognostic value of LINC01123 in OSCC.

RESULTS

The analysis results showed that LINC01123 was overexpressed in OSCC tumor tissues; also, the prognosis of patients with OSCC with high LINC01123 expression levels was poor. The knockdown of LINC01123 inhibited the proliferation, migration, and invasion of OCSS cells. MiR-34a-5p was a target of LINC01123, and its inhibitor could reverse the effect of silenced LINC01123 on the progression of OSCC.

CONCLUSIONS

Highly expressed LINC01123 was associated with poor prognosis of OSCC and regulated OSCC cell proliferation, invasion, and migration by sponging miR-34a-5p. Therefore, the LINC01123/miR-34a-5p axis may provide new ideas for the prognosis and treatment of OSCC.

Impact of Environmental and Pharmacologic Changes on the Upper Gastrointestinal Microbiome

Diseases of the upper gastrointestinal tract have become more prevalent over time. Mechanisms of disease formation are still only partially understood. Recent literature has shown that the surrounding microbiome affects the propensity for disease formation in various parts of the upper gastrointestinal tract. A review was performed of any literature to our best knowledge concerning the effects of pharmacologic agents, environmental changes, and surgical intervention on the microbiome of the upper gastrointestinal tract. Searches of the literature were performed using specific keywords related to drugs, surgical procedures, and environmental factors. Many prescription and nonprescription drugs that are commonly used have varying effects on the upper gastrointestinal tract. Proton pump inhibitors may affect the relative prevalence of some organisms in the lower esophagus and have less effect in the proximal esophagus. Changes in the esophageal microbiome correlate with some esophageal diseases. Drugs that induce weight loss have also been shown to affect the microbiomes of the esophagus and stomach. Common surgical procedures are associated with shifts in the microbial community in the gastrointestinal tract. Environmental factors have been shown to affect the microbiome in the upper gastrointestinal tract, as geographic differences correlate with alterations in the microbiome of the gastrointestinal tract. Understanding the association of environmental and pharmacologic changes on the microbiome of the upper gastrointestinal tract will facilitate treatment plans to reduce morbidity from disease.

LPS stimulates gingival fibroblasts to express PD-L1 via the p38 pathway under periodontal inflammatory conditions

OBJECTIVE

The overall aim of this research was to investigate the differences in the expression of programmed death ligand 1 (PD-L1) in human gingival fibroblasts (HGFs) between a periodontal healthy group and a periodontal inflammatory group. and explore the possible mechanism involved.

METHODS

Differences in PD-L1 mRNA and protein expression in HGFs from a periodontal healthy group and a periodontal inflammatory group were examined by qPCR and western blotting, respectively, and were further tested after lipopolysaccharide (LPS) stimulation in both groups. The effects of a p38 pathway inhibitor on the changes in p38 phosphorylation levels and PD-L1 expression after LPS stimulation were investigated in both groups.

RESULTS

PD-L1 mRNA and protein levels in HGFs in the periodontal inflammatory group were significantly higher than those in the periodontal healthy group (p < 0.05). After 10 μg/mL LPS stimulation, PD-L1 mRNA levels in HGFs from both groups increased significantly (p < 0.05), peaking at 4 h, and the peak was significantly higher in the periodontal inflammatory group than in the periodontal healthy group (p < 0.05). However, PD-L1 protein expression was upregulated only in the inflammatory group (p < 0.05). Inhibition of the p38 pathway in HGFs decreased p38 phosphorylation in both groups (p < 0.05) but this treatment reversed the LPS-induced increase in PD-L1 mRNA and protein levels only in the inflammatory group (p < 0.05).

CONCLUSION

In the periodontal inflammatory state, the expression of PD-L1 in HGFs is more easily activated, and may be influenced by the p38 pathway.

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.

High fat diet, gut microbiome and gastrointestinal cancer

Gastrointestinal cancer is currently one of the main causes of cancer death, with a large number of cases and a wide range of lesioned sites. A high fat diet, as a public health problem, has been shown to be correlated with various digestive system diseases and tumors, and can accelerate the occurrence of cancer due to inflammation and altered metabolism. The gut microbiome has been the focus of research in recent years, and associated with cell damage or tumor immune microenvironment changes via direct or extra-intestinal effects; this may facilitate the occurrence and development of gastrointestinal tumors. Based on research showing that both a high fat diet and gut microbes can promote the occurrence of gastrointestinal tumors, and that a high fat diet imbalances intestinal microbes, we propose that a high fat diet drives gastrointestinal tumors by changing the composition of intestinal microbes.

Shikonin-mediated PD-L1 degradation suppresses immune evasion in pancreatic cancer by inhibiting NF-κB/STAT3 and NF-κB/CSN5 signaling pathways

BACKGROUND

Pancreatic cancer (PC) is a highly fatal malignancy with few effective therapies currently available. Recent studies have shown that PD-L1 inhibitors could be potential therapeutic targets for the treatment of PC. The present study aims to investigate the effect of Shikonin on immune evasion in PC with the involvement of the PD-L1 degradation.

METHODS

Initially, the expression patterns of PD-L1 and NF-κB in PC were predicted in-silico using the GEPIA database, and were subsequently validated using PC tissues. Thereafter, the correlation of NF-κB with STAT3, CSN5 and PD-L1 was examined. PC cells were treated with Shikonin, NF-κB inhibitor, STAT3 activator, and CSN5 overexpression plasmid to investigate effects on PD-L1 glycosylation and immune evasion in PC. Finally, in vivo tumor formation was induced in C57BL/6J mice, in order to verify the in vitro results.

RESULTS

PD-L1, NF-κB, NF-κB p65, STAT3, and CSN5 were highly expressed in PC samples, and NF-κB was positively correlated with STAT3/CSN5/PD-L1. Inhibition of NF-κB decreased PD-L1 glycosylation and increased PD-L1 degradation, whereas activated STAT3 and overexpressed CSN5 reversed these trends. Shikonin blocked immune evasion in PC, and lowered the expression of PD-L1, NF-κB, NF-κB p65, STAT3 and CSN5 in vivo and in vitro.

CONCLUSION

The findings indicated Shikonin inhibited immune evasion in PC by inhibiting PD-L1 glycosylation and activating the NF-κB/STAT3 and NF-κB/CSN5 signaling pathways. These effects of Shikonin on PC cells may bear important potential therapeutic implications for the treatment of PC.

Regulation of PD-L1 expression in the tumor microenvironment

Programmed death-ligand 1 (PD-L1) on cancer cells engages with programmed cell death-1 (PD-1) on immune cells, contributing to cancer immune escape. For multiple cancer types, the PD-1/PD-L1 axis is the major speed-limiting step of the anti-cancer immune response. In this context, blocking PD-1/PD-L1 could restore T cells from exhausted status and eradicate cancer cells. However, only a subset of PD-L1 positive patients benefits from α-PD-1/PD-L1 therapies. Actually, PD-L1 expression is regulated by various factors, leading to the diverse significances of PD-L1 positivity. Understanding the mechanisms of PD-L1 regulation is helpful to select patients and enhance the treatment effect. In this review, we focused on PD-L1 regulators at the levels of transcription, post-transcription, post-translation. Besides, we discussed the potential applications of these laboratory findings in the clinic.

Association between Inflammation and Function of Cell Adhesion Molecules Influence on Gastrointestinal Cancer Development

Gastrointestinal cancer is highly associated with inflammatory processes inducing the release of cytokines from cancer or immune cells, including interferons, interleukins, chemokines, colony-stimulating factors, and growth factors, which promote or suppress tumor progression. Inflammatory cytokines within the tumor microenvironment promote immune cell infiltration. Infiltrating immune, and tumor-surrounding stromal cells support tumor growth, angiogenesis, metastasis, and immunosuppression through communication with inflammatory cytokines and cell adhesion molecules. Notably, infiltrating immune and tumor cells present immunosuppressive molecules, such as programmed death-ligand 1 (PD-L1) and CD80/CD86. Suppression of cytotoxic T cells promotes tumor avoidance of immune surveillance and greater malignancy. Moreover, glycosylation and sialylation of proteins hyperexpressed on the cancer cell surface have been shown to enhance immune escape and metastasis. Cytokine treatments and immune checkpoint inhibitors are widely used in clinical practice. However, the tumor microenvironment is a rapidly changing milieu involving several factors. In this review, we have provided a summary of the interactions of inflammation and cell adhesion molecules between cancer and other cell types, to improve understanding of the tumor microenvironment.

Dysbiosis of gut microbiota in patients with esophageal cancer

A number of studies have identified that gut microbiota influences the development of cancer. However, there is little known about gut microbiota and esophageal cancer (EC). The aim of this study was to investigate the gut microbiota profile associated with EC. In this study, 23 patients with EC and 23 sex- and age-matched healthy controls (NC) were recruited between July 2019 and August 2019 at Huai'an First People's Hospital (Huai'an, China) and the gut microbiota was analyzed by 16S rRNA gene sequencing of fresh stool samples. We found that the microbial richness of intestinal flora in patients with EC were higher than NC, whereas evenness did not change obviously. Principal coordinate analysis (PCoA) and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) analysis both revealed that a distinct separation in bacterial community composition between the EC and NC. At the phylum level, the EC group showed significantly higher abundances of Firmicutes and Actinobacteria, but a lower Bacteroidetes than NC. At the genus level, a significantly increased abundance of Streptococcus, Bifidobacterium, Subdoligranulum, Blautia, Romboutsia, Collinsella, Paeniclostridium, Dorea, and Atopobium were observed in EC patients, while Lachnospira, Bacteroides, Agathobacter, Lachnoclostridium, Parabacteroides, Paraprevotella, Butyricicoccus, Tyzzerella, Fusicatenibacter, and Sutterella were reduced. Receiver operating characteristic (ROC) analysis revealed that Lachnospira, Bacteroides, Streptococcus, and Bifidobacterium both achieved a high accuracy in EC diagnosis (area under the curve was more than 0.85), and the Lachnospira was found to be the best classifier. This study firstly characterized the gut microbiota composition of EC patients and screened out the optimal potential microbiota biomarkers for EC diagnosis. It may provide a fundamental reference for further studies on the gut microbiome for the diagnosis and treatment of EC.

Helicobacter pylori Virulence Factors-Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

Gastric cancer constitutes one of the most prevalent malignancies in both sexes; it is currently the fourth major cause of cancer-related deaths worldwide. The pathogenesis of gastric cancer is associated with the interaction between genetic and environmental factors, among which infection by Helicobacter pylori (H. pylori) is of major importance. The invasion, survival, colonization, and stimulation of further inflammation within the gastric mucosa are possible due to several evasive mechanisms induced by the virulence factors that are expressed by the bacterium. The knowledge concerning the mechanisms of H. pylori pathogenicity is crucial to ameliorate eradication strategies preventing the possible induction of carcinogenesis. This review highlights the current state of knowledge and the most recent findings regarding H. pylori virulence factors and their relationship with gastric premalignant lesions and further carcinogenesis.

Protective Role of Somatostatin in Sepsis-Induced Intestinal Barrier Dysfunction through Inhibiting the Activation of NF-κB Pathway

Somatostatin (SST) has a protective role in intestinal injury, inflammatory response, and intestinal mucosal barrier in rats with acute pancreatitis. However, its function in sepsis-induced intestinal barrier dysfunction remains largely unknown. A mouse sepsis model was constructed, and SST was injected into the tail vein. Then, hematoxylin and eosin staining (HE) was used to detect the intestinal barrier dysfunction. Enzyme-linked immunosorbent assay was used to detect the level of tumor necrosis factor α- (TNF-) α, interleukin- (IL-) 6, and interleukin- (IL-) 10 in the ileum. Expressions of tight junction proteins, zonula occludens- (ZO-) 1 and Claudin-1, and NF-κB p65 in the ileum were detected using western blot and immunohistochemistry as needed. Furthermore, JSH-23 as an inhibitor of the NF-κB pathway was injected into sepsis mice with SST or not. Mice with sepsis showed an obvious intestinal barrier dysfunction with decreasing specific somatostatin receptor subtype (SSTRs), and increasing TNF-α, IL-6, and IL-10 in the ileum. SST could relieve the injury, the decrease of SSTRs, and the increase of TNF-α and IL-6 induced by sepsis and also further enhanced the expression of IL-10. Further analysis showed that ZO-1 and Claudin-1 were reduced in the ileum by sepsis but enhanced by SST. NF-κB p65 was promoted in the ileum by sepsis but inhibited by SST. Further experiments confirmed that NF-κB inhibitor JSH-23 could repair the intestinal barrier dysfunction and enhance the protective effect of SST on the intestinal barrier. SST, with a protective effect on intestinal barrier dysfunction through suppression of NF-κB, could be a potential therapeutic drug for sepsis-induced intestinal barrier dysfunction.

Regulation of PD-L1 Expression by NF-κB in Cancer

Immune checkpoints are inhibitory receptor/ligand pairs regulating immunity that are exploited as key targets of anti-cancer therapy. Although the PD-1/PD-L1 pair is one of the most studied immune checkpoints, several aspects of its biology remain to be clarified. It has been established that PD-1 is an inhibitory receptor up-regulated by activated T, B, and NK lymphocytes and that its ligand PD-L1 mediates a negative feedback of lymphocyte activation, contributing to the restoration of the steady state condition after acute immune responses. This loop might become detrimental in the presence of either a chronic infection or a growing tumor. PD-L1 expression in tumors is currently used as a biomarker to orient therapeutic decisions; nevertheless, our knowledge about the regulation of PD-L1 expression is limited. The present review discusses how NF-κB, a master transcription factor of inflammation and immunity, is emerging as a key positive regulator of PD-L1 expression in cancer. NF-κB directly induces PD-L1 gene transcription by binding to its promoter, and it can also regulate PD-L1 post-transcriptionally through indirect pathways. These processes, which under conditions of cellular stress and acute inflammation drive tissue homeostasis and promote tissue healing, are largely dysregulated in tumors. Up-regulation of PD-L1 in cancer cells is controlled via NF-κB downstream of several signals, including oncogene- and stress-induced pathways, inflammatory cytokines, and chemotherapeutic drugs. Notably, a shared signaling pathway in epithelial cancers induces both PD-L1 expression and epithelial–mesenchymal transition, suggesting that PD-L1 is part of the tissue remodeling program. Furthermore, PD-L1 expression by tumor infiltrating myeloid cells can contribute to the immune suppressive features of the tumor environment. A better understanding of the interplay between NF-κB signaling and PD-L1 expression is highly relevant to cancer biology and therapy.

Alpha-Fetoprotein Regulates the Expression of Immune-Related Proteins through the NF-κB (P65) Pathway in Hepatocellular Carcinoma Cells

Background

The prognosis of patients with hepatocellular carcinoma (HCC) is poor, with 60% to 70% of patients developing recurrence and metastasis within five years of radical resection. Alpha-fetoprotein (AFP) plays a significant role in predicting the recurrence and metastasis of HCC after surgery. However, its role in modulating tumor immunity has not been investigated. Our objective was to examine the effect of AFP on the expression of B7 family and activation of the NF-κB (P65) pathway in HCC.

Methods

We generated human hepatoma SMMC-7721 cell lines with or without recombinant AFP transfection (AFPup and control groups). Colony formation assay, Transwell invasion assay, and wound healing assay were used to detect the function of AFP. Liver cancer xenografts were made in BALB/c nude male mice (N = 6 per group). After 28 days of inoculation, the expression of immune genes in the HCC tissues, including PD-L (B7-H1), B7-H3, B7-H4, and P65, was evaluated by quantitative real-time PCR (qPCR) and western blot. In addition, immunofluorescence was used to determine the subcellular localization of the P65 protein, a key factor in the NF-κB pathway. An online HCC patients' dataset was also used to detect the connection between AFP and P65.

Results

Overexpression of AFP could enhance proliferation, invasion, and migration of HCC cells. Both qPCR and western blot results demonstrated that the expressions of PD-L1, B7-H4, and P65 were significantly higher in the AFP group compared to the controls (P < 0.05). Immunofluorescence results indicated that the majority of the P65 protein was located in the cytoplasm in the control group but was translocated to the nucleus in the AFPup group. The Spearman correlation coefficient confirms that AFP has a positive correlation with P65 in HCC patients (R = 0.33, P=0.05).

Conclusion

AFP could enhance proliferation, invasion, and migration in HCC cells. The upregulation of AFP would increase the PD-L1 and B7-H4 mRNA and protein expression in HCC tissues through the upregulation and activation of the P65 protein.

Profiles of PD-1, PD-L1, PD-L2 in Gastric Cancer and Their Relation with Mutation, Immune Infiltration, and Survival

Background

Although multiple types of cancers demonstrated favorable outcome after immunotherapy of PD-1/PD-L1 blockade, the specific regulatory mechanism of PD genes in gastric cancer (GC) remains largely unknown.

Materials and Methods

Expression of RNA, copy number variants, and clinical parameters of GC individuals from TCGA were analyzed. Coexpressed genes for PD-1, PD-L1, and PD-L2 were selected by correlation analysis and confirmed by STRING. Gene Ontology and KEGG pathway analyses were performed by clusterProfiler. The influence of PD-1/PD-L1/PD-L2 on immune cell infiltration was investigated by MCP-counter.

Results

PD-L2 demonstrated significant relation with clinical stage of GC (P = 0.043). Survival analysis showed that PD-1 expression was correlated with better prognosis of GC patients (HR = 0.70, P = 0.031), but PD-L2 expression was related with worse survival (HR = 1.42, P = 0.032). Mutation of PIK3CA could alter the level of PD-1, PD-L1, and PD-L2 (P < 0.001), and TP53 mutation demonstrated significant correlation with PD-L1 (P = 0.015) and PD-L2 (P = 0.014) expression. Enrichment analysis of PD-1/PD-L1/PD-L2 coexpressed genes indicated a biological process of mononuclear cell proliferation, leukocyte cell-cell adhesion, and lymphocyte activation as well as KEGG pathways including cell differentiation of Th1 and Th2, cell differentiation of Th17, and hematopoietic cell landscape. As for immune infiltration analysis, PD-1 was mainly related with cytotoxic lymphocytes and endothelial cells; PD-L1 were associated with monocytic lineage; PD-L2 showed significant correlation with myeloid dendritic cells.

Conclusion

PD-1 expression showed association with better prognosis of GC, and PD-L2 expression was related with worse survival. Mutations of PIK3CA and TP53 significantly correlated with PD-1/PD-L1/PD-L2 axis. PD-1/PD-L1/PD-L2 coexpressed genes demonstrated enrichment in mononuclear cell proliferation, leukocyte cell-cell adhesion, and lymphocyte activation as well as KEGG pathways including cell differentiation of Th1, Th2, and Th17.

NF-κB and Its Role in Checkpoint Control

Nuclear factor-κB (NF-κB) has been described as one of the most important molecules linking inflammation to cancer. More recently, it has become clear that NF-κB is also involved in the regulation of immune checkpoint expression. Therapeutic approaches targeting immune checkpoint molecules, enabling the immune system to initiate immune responses against tumor cells, constitute a key breakthrough in cancer treatment. This review discusses recent evidence for an association of NF-κB and immune checkpoint expression and examines the therapeutic potential of inhibitors targeting either NF-κB directly or molecules involved in NF-κB regulation in combination with immune checkpoint blockade.

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

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.

The TLR4/ERK/PD‑L1 axis may contribute to NSCLC initiation

Infection and inflammation serve an important role in tumor development. Toll-like receptor 4 (TLR4) is a pivotal component of the innate and adaptive immune response during infection and inflammation. Programmed-death ligand 1 (PD-L1) is hypothesized as an important factor for non-small cell lung cancer (NSCLC) immune escape. In the present study, the relationship between TLR4 and PD-L1, in addition to the associated molecular mechanism, were investigated. TLR4 and PD-L1 expression in lung cancer tissues were detected using immunohistochemistry, whilst overall patient survival was measured using the Kaplan-Meier method. The A549 cell line stimulated using lipopolysaccharide (LPS) was applied as the in vitro inflammatory NSCLC model. Associated factors were investigated using reverse transcription-quantitative PCR and western blotting. Lung cancer tissues exhibited increased PD-L1 and TLR4 levels compared with those of adjacent para-cancerous tissues, where there was a positive correlation between TLR4 and PD-L1 expression. In addition, increased expression of these two proteins was found to be linked with poorer prognoses. Following the stimulation of A549 cells with LPS, TLR4 and PD-L1 expression levels were revealed to be upregulated in a dose-dependent manner, where the ERK and PI3K/AKT signaling pathways were found to be activated. Interestingly, in the presence of inhibitors of these two pathways aforementioned, upregulation of PD-L1 expression was only inhibited by the MEK inhibitor PD98059, which can inhibit ERK activity. These data suggested that the ERK signaling pathway is necessary for the TLR4/PD-L1 axis. In conclusion, data from the present study suggest that TLR4 and PD-L1 expression can serve as important prognostic factors for NSCLC, where TLR4 activation may induce PD-L1 expression through the ERK signaling pathway.

Epigenetic induction of tumor stemness via the lipopolysaccharide-TET3-HOXB2 signaling axis in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell cancer (ESCC) is one kind of frequent digestive tumor. The inflammatory environment plays an important role in the tumorigenesis and development of ESCC. Cancer stem cells are a small group of tumor cells with stem cell characteristics, which can potentially hinder the tumor management and treatment.

METHODS

ELISA was performed to detect the lipopolysaccharide concentration in cancer tissues. qPCR, Western blot, FACS, Immunohistochemistry, Immunofluorescence and Dot blot were applied to detect target genes expression. CCK-8, Colony-formation, Transwell, Sphere and Xenograft were conducted to investigate the function of cells, influenced by risk factors. The survival curve was drawn with the Kaplan-Meier product limit estimator. Nano-hmC-Seal-seq was utilized to detect the downstream target of TET3. ChIP-qPCR was adopted to demonstrate the transcriptional regulation of stem cell-associated genes by HOXB2.

RESULTS

Lipopolysaccharide concentration was significantly up-regulated in ESCC. High concentration of lipopolysaccharide stimulation induced the stemness of ESCC cells. TET3 expression was elevated with lipopolysaccharide stimulation via p38/ERK-MAPK pathway in ESCC and negatively correlated with patients' survival. TET3 induced the stemness of ESCC cells. Nano-hmC-Seal-seq showed that TET3 overexpression led to a significant increase in 5hmC levels of HOXB2 gene region, which was thus identified as the downstream target of TET3. The binding of HOXB2 to NANOG and cMYC was verified by ChIP-qPCR.

CONCLUSIONS

Lipopolysaccharide served as a tumor promotor in ESCC by inducing cancer cell stemness through the activation of a LPS-TET3-HOXB2 signaling axis, which might provide a novel therapeutic strategy for ESCC. Video Abstract.

How does Helicobacter pylori cause gastric cancer through connexins: An opinion review

Helicobacter pylori (H. pylori) is a Gram-negative bacterium with a number of virulence factors, such as cytotoxin-associated gene A, vacuolating cytotoxin A, its pathogenicity island, and lipopolysaccharide, which cause gastrointestinal diseases. Connexins function in gap junctional homeostasis, and their downregulation is closely related to gastric carcinogenesis. Investigations into H. pylori infection and the fine-tuning of connexins in cells or tissues have been reported in previous studies. Therefore, in this review, the potential mechanisms of H. pylori-induced gastric cancer through connexins are summarized in detail.