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Programmed cell death‐ligand 1 (PD‐L1) expressed on cancer cells can cause immune escape of non‐small‐cell lung cancer (NSCLC). Elucidation of the regulatory mechanisms of the PD‐L1 expression is a prerequisite for establishing new tumor immunotherapy strategies. Ubiquitin C‐terminal hydrolase L1 (UCHL1) is a regulator of cellular signaling transduction that is aberrantly expressed in NSCLC. However, it is not known whether UCHL1 regulates the expression of PD‐L1 in NSCLC cells. In the present study, we found that UCHL1 promotes the expression of PD‐L1 in NSCLC cell lines. In addition, UCHL1 expressed in NSCLC cells inhibited activation of Jurkat cells through upregulation of PD‐L1 expression in in vitro experiments. Moreover, UCHL1 upregulates PD‐L1 expression through facilitating activation of the AKT‐P65 signaling pathway. In conclusion, these results indicated that UCHL1 promoted PD‐L1 expression in NSCLC cells. This finding implied that inhibition of UCHL1 might suppress immune escape of NSCLC through downregulation of PD‐L1 expression in NSCLC cells., Deubiquitinase ubiquitin C‐terminal hydrolase L1 (UCHL1) is a regulator of cellular signaling transduction that is aberrantly expressed in non‐small‐cell lung cancer (NSCLC). We analyzed the relationship between deubiquitinase UCHL1 and immune checkpoint molecule programmed cell death‐ligand 1 (PD‐L1) in NSCLC cells. Our results showed that UCHL1 promoted expression of PD‐L1 through the Akt‐P65 signaling axis.

Macroautophagy/autophagy is an evolutionarily conserved process that involves the selective degradation of cytoplasmic components within lysosomes in response to starvation. Autophagy is an ancient defense mechanism that has been closely integrated with the immune system and has multiple effects on innate and adaptive immunity. The pro-inflammatory and anti-inflammatory cytokines can activate and inhibit autophagy, respectively. TNFAIP8L2/TIPE2 (tumor necrosis factor, alpha-induced protein 8-like 2) is a newly identified immune negative regulator of innate and adaptive immunity that plays an important role in immune homeostasis. However, whether and how TNFAIP8L2 controls autophagy is still unknown. Murine TNFAIP8L2 can directly bind to and block the RAC1 GTPase activity to regulate innate immunity. RAC1 can also bind to MTOR and regulate MTORC1 cellular localization and activity. Here, we find that TNFAIP8L2 can compete with MTOR for binding to the GTP-bound state of RAC1 and negatively regulate MTORC1 activity. Interestingly, TNFAIP8L2 overexpression fails to induce autophagy flux by the suppression of the MTOR activity under glutamine and serum starvation. Instead, TNFAIP8L2 appears to impair autophagic lysosome reformation (ALR) during prolonged starvation. Finally, we demonstrate that TNFAIP8L2 overexpression leads to a defect in MTOR reactivation and disrupts autophagy flux, thereby leading to cell death. Furthermore, TNFAIP8L2 deficiency can exacerbate the inflammatory response and lung injury by controlling the MTOR activity in an LPS-induced mouse endotoxemia model. Our study reveals a novel role of TNFAIP8L2 in autophagy by regulating the RAC1-MTORC1 axis that supports its potential as a target for therapeutic treatment.Abbreviations: ALR: autophagic lysosome reformation; BafA1: bafilomycin A1; BMDMs: bone marrow-derived macrophages; Co-IP: Co-Immunoprecipitation; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTORC1: mechanistic target of rapamycin kinase complex 1; RAPA: rapamycin; RPS6: ribosomal protein S6; SQSTM1/p62: sequestosome 1; Starv: Starvation; TNFAIP8L2/TIPE2: tumor necrosis factor-alpha-induced protein-8 like-2.

Brain-derived neurotrophic factor (BDNF) is a growth factor that plays vital roles in the neuron survival, growth, and neuroplasticity. Alteration to BDNF expression is associated with major depressive disorder. However, the BDNF translational machinery in depression remains unknown. Herein, we pointed that Pdcd4, a suppressor oncogene, acted as an endogenous inhibitor for the translation of BDNF, and selectively repressed the translation of BDNF splice variant IIc mRNA in an eIF4A-dependent manner. Chronic restraint stress (CRS) up-regulated Pdcd4 expression in hippocampus via decreasing mTORC1-mediated proteasomes degradation pathway, which resulted in the reduction of BDNF protein expression. Moreover, over-expression of Pdcd4 in the hippocampus triggered spontaneous depression-like behaviors under the non-stressed conditions in mice, while systemic or neuron-specific knockout of Pdcd4 reverses CRS-induced depression-like behaviors. Importantly, administration of Pdcd4 siRNA or an interfering peptide that interrupts the Pdcd4-eIF4A complex substantially promoted BDNF expression and rescued the behavioral disorders which were caused by CRS. Overall, we have discovered a previously unrecognized role of Pdcd4 in controlling BDNF mRNA translation, and provided a new method that boosting BDNF expression through blocking the function of Pdcd4 in depression, indicating that Pdcd4 might be a new potential target for depressive disorder therapy.

A20 is a prototypical anti-inflammatory molecule that is linked to multiple human diseases, including cancers. The role of A20 as a tumor suppressor was first discovered in B cell lymphomas. Subsequent studies revealed the dual roles of A20 in solid cancers. This review focuses on the roles of A20 in different cancer types to demonstrate that the effects of A20 are cancer type-dependent. A20 plays antitumor roles in colorectal carcinomas and hepatocellular carcinomas, whereas A20 acts as an oncogene in breast cancers, gastric cancers and melanomas. Moreover, the roles of A20 in the setting of glioma therapy are context-dependent. The action mechanisms of A20 in different types of cancer are summarized. Additionally, the role of A20 in antitumor immunity is discussed. Furthermore, some open questions in this rapidly advancing field are proposed. Exploration of the actions and molecular mechanisms of A20 in cancer paves the way for the application of A20-targeting approaches in future cancer therapy.

Endometrial carcinoma is one of the most common malignancies in the female reproductive system. Interleukin-37 (IL-37) is a newly discovered anti-inflammatory factor belonging to the IL-1 family. IL-37 has five different isoforms, and IL-37b is the most biologically functional subtype. In recent years, the protective roles of IL-37 in different cancers, including lung and liver cancers, have been successively reported. IL-37 also plays an important role in some gynecological diseases such as endometriosis, adenomyosis, and cervical cancer. However, the role and mechanism of IL-37b, especially the mature form of IL-37b, in endometrial carcinoma have not been elucidated. The present study demonstrated that IL-37 protein was downregulated in endometrial carcinoma cells compared with the control endometrium. IL-37b did not affect the proliferation and colony-forming ability of endometrial cancer cells. A mature form of IL-37b (IL-37bΔ1-45) effectively suppressed the migration and invasion of endometrial cancer cells by decreasing the expression of matrix metalloproteinase 2 (MMP2) via Rac1/NF-κB signal pathway. However, it did not affect epithelial-mesenchymal transition (EMT) or filamentous actin (F-actin) depolymerization of endometrial cancer cells. IL-37bΔ1-45 attenuated tumor metastasis in a peritoneal metastatic xenograft model of endometrial cancer. To sum up, these results suggested IL-37b could be involved in the pathogenesis of endometrial carcinoma and provide a novel target for the diagnosis and treatment of endometrial carcinoma.

Transcription factor EB (TFEB) is a master regulator of autophagy and lysosomal biogenesis. The post-translational phosphorylation modulations of TFEB by mTOR and ERK signaling can determine its nucleocytoplasmic shuttling and activity in response to nutrient availability. However, regulations of TFEB at translational level are rarely known. Here, we found that programmed cell death 4 (PDCD4), a tumor suppressor, decreased levels of nuclear TFEB to inhibit lysosome biogenesis and function. Mechanistically, PDCD4 reduces global pool of TFEB by suppressing TFEB translation in an eIF4A-dependent manner, rather than influencing mTOR- and ERK2-dependnet TFEB nucleocytoplasmic shuttling. Both of MA3 domains within PDCD4 are required for TFEB translation inhibition. Furthermore, TFEB is required for PDCD4-mediated lysosomal function suppression. In the tumor microenvironment, PDCD4 deficiency promotes the anti-tumor effect of macrophage via enhancing TFEB expression. Our research reveals a novel PDCD4-dependent TFEB translational regulation and supports PDCD4 as a potential therapeutic target for lysosome dysfunction related diseases.

The effectiveness of immunotherapy targeting the immune checkpoint PD-L1/PD-1 pathway highlights importance of elucidating the regulatory mechanisms of PD-L1 expression in cancer cells. Previous studies demonstrate that oncogene MYC up-regulates PD-L1 expression in lymphomas. In the present study, we investigated the regulatory role of MYC in the PD-L1 expression induced by IFN-γ in HCC cells. Unexpectedly, knockdown of MYC expression using siRNA assay increased the inducible expression of PD-L1 both at mRNA and protein levels. Mechanistically, the inhibition of MYC elevated expression of STAT1, a critical component of IFN-γ signaling pathway, leading to the elevation of PD-L1 expression in HCC cells exposed to IFN-γ. These results suggest that MYC may down-regulate PD-L1 expression in the context of HCC. This study implicates that a combination therapy targeting MYC function and PD-L1/PD-1 pathway might be effective for treatment of HCC.

Aim: Exosomes are nanoscale membranous vesicles secreted by most cell types able to transfer bioactive molecules among cells, which play crucial roles in intercellular communication. We characterized the exosomes derived from Toxoplasma gondii and detected the immune response in macrophages. Methods: We used transmission electron microscopy, nanotracking analysis and western blotting to identify T. gondii exosomes. Functional experiments were performed in RAW264.7 cells for the induction of cytokines, MAPKs (p38 MAPK, ERK 1/2 and c-Jun N-terminal kinase [JNK]), mRNAs and nuclear translocation of phosphorylated JNK protein. Results: JNK pathway was activated by T. gondii exosomes, and the production of IL-12, IFN-γ and TNF-α was significantly increased in macrophages. Conclusion: Our findings demonstrated that T. gondii exosomes elicit innate immune through JNK activation, which could provide new insight into the essential regulators of host–pathogen interactions.

Introduction Exosomes are nanograde membrane-bound vesicles secreted from most cell types through the fusion of multivesicular bodies with plasma membranes. Some of these exosomes are well defined, and are known to have immunomodulatory properties as well as play critical roles in intercellular communications. In this study, we characterized the exosomes derived from Toxoplasma gondii and their functions in aspect of immune responses. Methods T. gondii exosomes were isolated and identified using electron microscopy, nanoparticle tracking analysis, and Western blotting. The viability of macrophage RAW264.7 cells affected by exosomes was evaluated using a Cell Counting Kit (CCK-8). Then the uptake of T. gondii exosomes by RAW264.7 cells was detected by labeling with fluorescent dye PKH67. After exosomes stimulation, in vitro the production of interleukin (IL)-12, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10 in RAW264.7 cells were investigated using enzyme-linked immunosorbent assay (ELISA). In immunized BALB/c mice, the antibodies, cytokines as well as the percentage of CD4+ and CD8+ T cells were determined using ELISA and flow cytometric analysis. Protective efficacy was evaluated by challenging intraperitoneally with tachyzoites of T. gondii. Results We successfully isolated and characterized the exosomes derived from T. gondii. Functionally, the viability of macrophage RAW264.7 cells was significantly affected by exosomes at a high concentration (160 μg/mL). The production of IL-12, TNF-α and IFN-γ in macrophage cells were increased, and the level of IL-10 was decreased. Furthermore, BALB/c mice immunized with T. gondii exosomes showed both humoral and cellular immune responses and also exhibited a prolonged survival time. Conclusion T. gondii exosomes could modulate macrophage activation in vitro and trigger humoral and cellular immune responses and partial protection against acute parasite infection in mice, which suggested that exosomes may serve as a potential candidate against toxoplasmosis.

Background Interleukin-37 (IL-37) is a new negative immune regulator. It has 5 splicing forms, IL-37a–e, and most research mainly focuses on IL-37b functions in diverse diseases. Our previous research found that IL-37d inhibits lipopolysaccharide-induced inflammation in endotoxemia through a mechanism different from that of IL-37b. However, whether IL-37d plays a role in colitis and the underlying mechanisms is still obscure. Herein, we identified whether IL-37d regulates NLRP3 inflammasome activity and determined its effect on colitis. Methods NLRP3 inflammasome in macrophages from IL-37d transgenic (IL-37dtg) and control wild type (WT) mice were activated by lipopolysaccharide and adenosine 5′-triphosphate. The expression of NLRP3 inflammasome components and its downstream effector, IL-1β, were detected by real-time polymerase chain reaction, western blot, and ELISA. The models of alum-induced peritonitis and dextran sodium sulfate (DSS)-induced colitis were used to investigate the function of IL-37d on regulating the activity of NLRP3 inflammasome in vivo. Results Our results showed that the activation of NLRP3 inflammasome in macrophage and alum-induced peritonitis was inhibited by IL-37d. Strikingly, IL-37d suppressed NLRP3 expression at the priming step via inhibiting NF-κB activation by transcriptional profiling. Moreover, the recombinant protein IL-37d attenuated NLRP3 inflammasome activation and the production of IL-1β, which could be reversed by IL-1R8 knockdown. Finally, IL-37d transgenic mice resisted DSS-induced acute colitis and NLRP3 inflammasome activation. Conclusion Interleukin-37d inhibits overactivation of the NLRP3 inflammasome through regulating NLRP3 transcription in an IL-1R8 receptor-mediated signaling pathway.

Non-small cell lung cancer (NSCLC) is one of the leading causes of all cancer-related deaths worldwide. Despite extensive efforts to improve the diagnosis and treatment of this neoplasm, limited progress has been made. Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a newly introduced negative immune regulator, which also controls tumorigenesis. However, the role of TIPE2 in angiogenesis is unknown. In the present study, we investigated the expression and roles of TIPE2 in NSCLC. TIPE2 upregulation in human NSCLC tissues was negatively associated with the primary tumor size, lymph node metastasis, and advanced clinical stage, which can be used to predict lymph node metastasis. Moreover, overexpression of TIPE2 not only inhibited the colony formation, migration, and invasion of NSCLC cells but also indirectly suppressed the proliferation, migration, and tube formation of vascular endothelial cells. Furthermore, TIPE2 suppressed tumor invasiveness and angiogenesis via inhibiting the activation of Rac1 and subsequently weakening its downstream effects, including F-actin polymerization and VEGF expression. Collectively, these results indicate that TIPE2 plays a key role in NSCLC metastasis, suggesting that forced TIPE2 expression might be a novel strategy for the treatment of NSCLC.

Metastasis of hepatocellular carcinoma (HCC) can be facilitated by TNF-α, a prototypical inflammatory cytokine in the HCC microenvironment. A20 is a negative regulator of NF-κB signaling pathway. In the present study we ask whether A20 plays a role in HCC metastasis. We found that A20 expression was downregulated in the invasive cells of microvascular invasions (MVI) compared with the noninvasive cells in 89 tissue samples from patients with HCC by immunochemistry methods. Overexpression of A20 in HCC cell lines inhibited their motility induced by TNF-α. Furthermore, the overexpression of A20 inhibited epithelial-mesenchymal transition (EMT), FAK activation and RAC1 activity. By contrast, knockdown of A20 in one HCC cell line results in the converse. In addition, the overexpression of A20 restrained the formation of MVI in HCC xenograft in nude mice treated with TNF-α. All the results suggested that A20 functioned as a negative regulator in motility of HCC cells induced by TNF-α.

Programmed cell death 4 (PDCD4) has been identified as a tumor‑suppressor gene that inhibits neoplastic transformation, tumor progression, and protein translation. It has been reported that multiple factors participate in the regulation of PDCD4 mRNA and protein. The endometrium is regulated by changing concentrations of ovarian hormones, such as estrogen and progesterone, and shows periodical changes. However, whether ovarian hormones regulate PDCD4 expression remains unclear. This study aimed to explore the effect and mechanism of estrogen or progesterone on PDCD4 mRNA and protein expression in human endometrial cancer cells. The expression of PDCD4 mRNA and protein in Ishikawa and HEC‑1‑A cells was detected by quantitative real‑time PCR and western blot analysis. The signaling pathway‑related proteins were detected by western blot analysis. The results showed that PDCD4 mRNA levels exhibited no significant changes after treatment with estrogen or progesterone in both Ishikawa and HEC‑1‑A cell lines. Estrogen also had no obvious effect on PDCD4 protein expression. However, progesterone effectively decreased the expression of PDCD4 protein and the PI3K/AKT pathway may be involved in the downregulation of PDCD4 protein induced by progesterone. These results suggest that the downregulation of PDCD4 induced by progesterone affects the therapeutic efficacy of progesterone in human endometrial cancer or endometriosis, which may have important implications for progesterone treatment in the clinic.

IL-37 is a new member of IL-1 family and possesses five different isoforms (named as IL-37 a–e). IL-37b has been demonstrated as a physiological suppressor of immune responses. However, the function of other isoforms remains unknown. Here, we show that IL-37d possesses anti-inflammatory roles both in vitro and in vivo. Firstly, IL-37d is expressed in peripheral blood mononuclear cells (PBMCs) and umbilical cords-derived mesenchymal stem cells (UCMSCs). Secondly, IL-37d overexpression markedly inhibits IL-1β-induced IL-6 production in A549 cells. Consistently, bone marrow-derived macrophages (BMDMs) from IL-37d transgenic mice express low levels of pro-inflammatory cytokines (such as IL-6 and TNF-α) following LPS stimulation, compared with those from wild-type mice. Furthermore, IL-37d transgenic mice produce less pro-inflammatory cytokines, and show much less degree of LPS-induced endotoxemia in vivo. Mechanistically, IL-37d interacts with Smad3 and promotes nuclear translocation of pSmad3. SIS3 (a specific Smad3 inhibitor) treatment completely blocks the inhibitory effects of IL-37d. Thus, our data indicate that IL-37d is a functional cytokine that negatively regulates pro-inflammatory cytokines expression in a Smad3-dependent manner.

Endometriosis (EM) is a kind of estrogen-dependent disease in reproductive-age women. Ovarian EM is the most common type. Although EM is a benign disease, it shares many similar features with cancers. Programmed cell death 4 (PDCD4), a newly identified tumor suppressor, plays an important role in inhibiting tumorigenesis and tumor progression at the transcriptional and translational levels. To explore the roles of PDCD4 in EM, we detected the expression of PDCD4 in control endometrium and eutopic/ectopic endometrium of ovarian EM patients, and analyzed the effects of PDCD4 on the biological behaviors of endometrial cell lines and primary endometrial cells. The results demonstrated that PDCD4 was downregulated in eutopic and ectopic endometrium of EM patients compared with control endometrium. PDCD4 effectively inhibited the proliferation and colony-forming ability of endometrial cells maybe by inhibiting cell autophagy. In addition, PDCD4 also suppressed the migration and invasion ability of endometrial cells, the mechanism may be related to NF-κB/MMP2/MMP9 signal pathway. Taken together, these results suggest that PDCD4 could be involved in the pathogenesis of EM, and provide a novel approach to target the aberrant PDCD4 expression in EM.

Clinical benefit from immunotherapy of B7-H1/PD-1 checkpoint blockade indicates that it is important to understand the regulatory mechanism of B7-H1 expression in cancer cells. As an adaptive response to the endogenous antitumor immunity, B7-H1 expression is up-regulated in HCC cells. B7-H1 expression is induced mainly by IFN-γ released from tumor-infiltrating T cells in HCC. In addition, HCC is a prototype of inflammation-related cancer and TNF-α is a critical component of inflammatory microenvironment of HCC. In the present study, we asked whether TNF-α can promote the expression of B7-H1 induced by IFN-γ in HCC cells. We found that JAK/STAT1/IRF1 was the primary pathway responsible for induction of B7-H1 expression by IFN-γ in human HCC cell lines. TNF-α and IFN-γ synergistically induced the expression of B7-H1 in the HCC cells. Moreover, the mechanism of the synergy was that TNF-α enhanced IFN-γ signaling by upregulating the expression of IFN-γ receptors. Furthermore, B7-H1 expression induced synergistically by TNF-α and IFN-γ in murine HCC cells facilitated tumor growth in vivo. Our findings suggest that TNF-α may enhance the adaptive immune resistance mediated by IFN-γ-induced B7-H1 in HCC cells.

Background Although programmed cell death (PDCD) 4 is generally considered to be a new tumor suppressor, the consequence of Pdcd4 deficiency in tumorigenesis is not well established. The role of PDCD4 in colitis-associated colorectal carcinoma (CRC) remains unknown. Methods Experimental colitis and CRC were induced by dextran sodium sulfate and dextran sodium sulfate with azoxymethane, respectively, in wild type and Pdcd4 knockout (Pdcd4(-/-)) mice and were evaluated by clinical examination and histopathology. Levels of cytokines were detected by enzyme-linked immunosorbent assay. Changes in signaling pathways were examined by Western blot and immunofluorescent staining. Cell proliferation was determined by BrdU incorporation and Cell Counting Kit-8 staining. Results Pdcd4 deficiency not only aggravated the dextran sodium sulfate-induced acute colitis but also promoted the development of colitis-induced CRC. Mechanically, Pdcd4 deficiency accelerated epithelial cell proliferation during tumorigenesis, markedly up-regulated the expression of proinflammatory cytokines, such as interleukin (IL)-6, and enhanced the activation of signal transducer and activator of transcription (STAT3), a IL-6 downstream effector. Using purified cells, we found that Pdcd4 deficiency increased IL-6 expression in vitro and the susceptibility to IL-6/STAT3 pathway-mediated cell proliferation significantly. Furthermore, blockade of IL-6/STAT3 pathway through sgp130Fc reversed the promoting effect of Pdcd4 deficiency on colonic epithelial cell proliferation in vivo. Conclusion The Pdcd4 deficiency accelerates colitis and colitis-associated CRC presumably through up-regulating IL-6/STAT3 pathway, suggesting that PDCD4 plays a protective role in inflammation-associated carcinoma and might be a potential target for the treatment of CRC.

A growing body of evidence demonstrates that autophagy, an evolutionarily conserved intracellular degradation process, is involved in the pathogenesis of atherosclerosis and has become a potential therapeutic target. Here we tested the effect of two inhibitors of phosphatidylinositol 3-kinase, 3-methyladenine (3-MA) and 2-(4-morpholinyl)-8-phenyl-chromone (LY294002), commonly used as inhibitors of autophagy, in atherosclerosis in apolipoprotein E−/− mice. Systemic application of 3-MA but not LY294002 markedly reduced the size of atherosclerotic plaque and increased the stability of lesions in high-fat diet-fed mice as compared with controls. Furthermore, 3-MA had multiple atheroprotective effects, including modulating macrophage autophagy and foam cell formation and altering the immune microenvironment. Long-term treatment with 3-MA promoted oxidized low-density lipoprotein (oxLDL)-induced macrophage autophagy and suppressed foam cell formation and cell viability in vitro. Furthermore, systemic application of 3-MA promoted lipid droplet breakdown and decreased apoptosis, most likely associated with autophagy. 3-MA treatment strikingly enhanced the expression of immune-negative molecules such as interleukin 10 (IL-10), transforming growth factor β and IL-35, as well as forkhead box P3 (Foxp3), the specific transcriptional factor for regulatory T cells, but did not affect the level of proinflammatory cytokines in the arterial wall. We provide strong evidence for the potential therapeutic benefit of 3-MA in inhibiting atherosclerosis development and improving plaque stability.