Single-cell RNA sequence analysis reveals USP32 as a therapeutic target to mitigate PD-L1-driven colorectal tumorigenesis in vitro and in vivo.

(-)-Epigallocatechin gallate (EGCG) is now widely accepted as a non-toxic, effective cancer preventive compound. EGCG also acts as a synergist with anti-cancer drugs for cancer treatment. Considering the wide beneficial effects of EGCG, we think EGCG might have antitumor immunity. Programmed death-ligand 1 (PD-L1) expression on tumor cells is involved in PD-L1/PD-1 pathway. PD-L1 protein levels varied among 6 non-small human lung cancer cell lines (NSCLCs): LC-AI and Lu99 cell lines showed the highest PD-L1 expression, A549 and H322 cell lines were medium, and H1703 and H1299 were very low, independent on cancer cell lines. Since PD-L1 expression is induced by various cytokines and growth factors, we studied the effects of IFN-γ and EGF on cell-surface PD-L1 level using flow cytometry, and its gene expression using RT-PCR. Treatment with IFN-γ dose-dependently stimulated PD-L1 expression in both A549 and H1299 cells, and not effective on Lu99 cells, whereas treatment with EGF stimulated PD-L1 in Lu99 cells only. Pretreatment with EGCG for 3 h, dose-dependently inhibited INF-γ-induced PD-L1 gene expression and protein level on cell-surface in both A549 and H1299. It is important to note that EGCG also inhibited phosphorylation of STAT1. In addition, EGCG inhibited EGF-induced PD-L1 gene expression and protein level in Lu99 cells via inhibition of phosphorylation of Akt. In order to study the effects of EGCG in between rodent carcinogenesis experiment and antitumor immunity, green tea extract (GTE) was given to NNK-induced lung tumors in A/J mice, which showed significant reduction of PD-L1 protein level, determined by immunohistochemical analysis using anti-PD-L1 antibody. Furthermore, the group treated with NNK + GTE significantly showed reduced number of tumors per mouse from 3.2 to 2.2, and decreased tumor size. Treatment with Wortmannin, a PI3K inhibitor, as a control, did not inhibit PD-L1 expression in A549 and H1299 cells. The results strongly suggest that EGCG enhances antitumor immunity via inhibition of PD-L1 expression in cancer cells, resulting in significant cancer preventive activity. Citation Format: Anchalee Rawangkan, Keisuke Iida, Ryo Sakai, Hirota Fujiki, Masami Suganuma. Green tea catechin, EGCG, enhances antitumor immunity by down-regulation of PD-L1 expression in non-small human lung cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2665. doi:10.1158/1538-7445.AM2017-2665

IntroductionRecent data has demonstrated that hypoxia drives an immunosuppressive tumour microenvironment (TME) via various mechanisms including hypoxia inducible factor (HIF)-dependent upregulation of programmed death ligand 1 (PD-L1). Both hypoxia and an immunosuppressive TME are targetable independent negative prognostic factors for bladder cancer. Therefore we sought to investigate whether hypoxia is associated with upregulation of PD-L1 in the disease.Materials and methodsThree human muscle-invasive bladder cancer cell lines (T24, J82, UMUC3) were cultured in normoxia (20% oxygen) or hypoxia (1 and 0.1% oxygen) for 24 h. Differences in PD-L1 expression were measured using Western blotting, quantitative polymerase chain reaction (qPCR) and flow cytometry (≥3 independent experiments). Statistical tests performed were unpaired t tests and ANOVA. For in silico work an hypoxia signature was used to apply hypoxia scores to muscle-invasive bladder cancers from a clinical trial (BCON; n = 142) and TCGA (n = 404). Analyses were carried out using R and RStudio and statistical tests performed were linear models and one-way ANOVA.ResultsWhen T24 cells were seeded at < 70% confluence, there was decreased PD-L1 protein (p = 0.009) and mRNA (p < 0.001) expression after culture in 0.1% oxygen. PD-L1 protein expression decreased in both 0.1% oxygen and 1% oxygen in a panel of muscle-invasive bladder cancer cells: T24 (p = 0.009 and 0.001), J82 (p = 0.008 and 0.013) and UMUC3 (p = 0.003 and 0.289). Increasing seeding density decreased PD-L1 protein (p < 0.001) and mRNA (p = 0.001) expression in T24 cells grown in both 20 and 1% oxygen. Only when cells were 100% confluent, were PD-L1 protein and mRNA levels higher in 1% versus 20% oxygen (p = 0.056 and p = 0.037). In silico analyses showed a positive correlation between hypoxia signature scores and PD-L1 expression in both BCON (p = 0.003) and TCGA (p < 0.001) cohorts, and between hypoxia and IFNγ signature scores (p < 0.001 for both).ConclusionTumour hypoxia correlates with increased PD-L1 expression in patient derived bladder cancer tumours. In vitro PD-L1 expression was affected by cell density and decreased PD-L1 expression was observed after culture in hypoxia in muscle-invasive bladder cancer cell lines. As cell density has such an important effect on PD-L1 expression, it should be considered when investigating PD-L1 expression in vitro.

PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma

Background Effects of mesenchymal stem cells (MSCs) on tumors have been extensively studied in recent years, but results still remain controversial. In this study we investigated the roles of MSCs on the expression of programmed death-ligand 1 (PD-L1) in lung cancer cells. Since overexpression of PD-L1 has been found to attenuate body's immune system against tumor cells, PD-1/PD-L1 blockages have become the most effective immunotherapy to the late stage non-small cell lung cancer (NSCLC). Therefore, understanding the effects of MSCs on PD-L1 expression is critical in managing immunotherapy for NSCLC patients. Method PD-L1 expressions were tested in two NSCLC cell lines, A549 and H1299 using qRT-PCR and Western Blot to qualitatively measure mRNA and protein levels, respectively. MSCs were isolated from umbilical cord blood and co-cultured with A549 and H1299 cells in complete medium using Transwell filters for 24-h, 48-h and 72-h. Then both A549 and H1299 cells were collected and PD-L1 expressions were tested. MSC-Conditioned Medium (MSC-CM) was generated by culturing 80% confluence of MSCs with serum-free medium. After 48 h, the medium was collected as MSC-CM. Both A549 and H1299 were then cultured in MSC-CM for 24-h, 48-h and 72-h, and PD-L1 expressions were measured from these two cell lines separately. Result Both MSCs and MSC-CM significantly increased the PD-L1 mRNA levels in the two NSCLC cells, while the MSC-CM had stronger stimulation to PD-L1 expressions (P &amp;lt; 0.0001) comparing to MSCs treatment (P&amp;lt;0.01). A549 cells reached the most significant effect at 48-h, while H1299 cells attended the same effect at 24-h treatment. The similar results were observed with PD-L1 protein levels. Both cell lines showed increased PD-L1 protein expressions after treating with MSCs and MSC-CM, but the augmented scales were smaller than the mRNA levels. The PD-L1 protein expressions in A549 cells increased significantly (p &amp;lt; 0.05) at 48-h when treating with MSCs, while increased much higher when treating with MSC-CM (P &amp;lt; 0.01). H1299 cells also showed the similar increase in PD-L1 protein expressions after 24-h treatment. Conclusion Both MSCs and MSC-CM significantly increase PD-L1 expressions in lung cancer cells, which ultimately attenuate the immune system against tumor cells. Citation Format: Hui Zhao, Hui Yang, Jinqiu Sun, Guoqiang Liang, Qianqian Zhao, Xiufang Zhang, Shengxian Liang, Rui Guo, Li Zhong. Mesenchymal stem cells promote PD-L1 expression in lung cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6011.

To investigate the effect and mechanism of autophagy on the expression of neutrophil programmed death ligand-1 (PD-L1) in mice with sepsis. (1) In vivo experiment: male C57BL/6 mice aged 6-8 weeks were divided into sham operation group (Sham group), cecum ligation and perforation (CLP) group, and rapamycin (RAP)+CLP group by random number table with 10 mice in each group. The sepsis model was reproduced by CLP, and the cecum and perforation were not ligated in Sham group, and other operations were the same as CLP group. The mice in RAP+CLP group were intraperitoneally injected with autophagy agonist RAP 4 mg×kg-1×d-1 7 days before modeling, while the mice in Sham group and CLP group were not treated. Lung, liver, spleen and pancreas tissues were harvested for immunohistochemical staining 4 days after the operation, and the infiltration of neutrophils in various organs was observed under light microscope. Meanwhile, the expressions of immunosuppressive molecule PD-L1 and autophagy marker microtubule-associated protein 1 light chain 3 (LC3) in lung neutrophils were determined by immunofluorescence staining. (2) In vitro experiment: mouse bone marrow neutrophils were extracted and re-suspended to 1×1010/L, and they were divided into blank control group (without any treatment), RAP control group (RAP 100 μmol/L), autophagy inhibitor Bafilomycin A1 (Baf) control group (Baf 10 μmol/L), lipopolysaccharide (LPS) stimulation group (LPS 1 mg /L), RAP+LPS group, and Baf+LPS group. The latter two groups were pretreated with 100 μmol/L RAP or 10 μmol/L Baf 30 minutes before LPS stimulation, respectively. The expression of PD-L1 mRNA of neutrophils was determined by reverse transcription-polymerase chain reaction (RT-PCR) at 0, 4, 12 hours after LPS stimulation. At the same time, the expressions of PD-L1, LC3 and p62 at the protein level were determined by Western Blot. (1) In vivo experiment: according to immunohistochemical experiments, a large amount of infiltration of neutrophils in lung, liver, spleen and pancreas was found at 4 hours after CLP. In the immunofluorescence, with the time extension after CLP, the positive expression of LC3 in the lung tissue showed a decreased tendency, and PD-L1 expression was significantly increased. RAP pretreatment could promote the expression of LC3 and reduce the expression of PD-L1 in CLP mice. (2) In vitro experiment: in terms of mRNA levels, with the extension of LPS stimulation time, the expression of PD-L1 mRNA in mouse neutrophils was increased continuously, and peaked at 12 hours, it was significantly higher than that in the blank control group (2-ΔΔCT: 72.2±10.0 vs. 13.0±0.8, P < 0.01). Compared with LPS stimulation group, the expression of PD-L1 mRNA in RAP+LPS group was significantly down-regulated [12-hour PD-L1 mRNA (2-ΔΔCT): 47.4±7.3 vs. 72.2±10.0, P < 0.01]. In Baf+LPS group, PD-L1 mRNA expression was significantly up-regulated as compared with that in LPS stimulation group [12-hour PD-L1 mRNA (2-ΔΔCT): 109.1±7.4 vs. 72.2±10.0, P < 0.01]. At the protein levels, at 4 hours after LPS stimulation, the positive expressions of PD-L1, LC3 and p62 were increased significantly as compared with those in the blank control group, and PD-L1 and p62 were increased continuously with time. Compared with the LPS stimulation group, the expressions of PD-L1 and p62 in the RAP+LPS group were significantly down-regulated, while the expression of LC3 was continually increased, indicating that the level of autophagy was increased, and autophagy was circulated smoothly. On the contrary, the expressions of PD-L1, LC3 and p62 in the Baf+LPS group were significantly up-regulated, indicating that the binding of autophagy and lysosome was blocked, and autophagy was not smooth. In sepsis, the infiltration of neutrophils in all organs increased, and the expression of PD-L1 of neutrophils in lungs was increased significantly, while the expression level of autophagy was decreased. The expression of PD-L1 stimulated by LPS can be inhibited by autophagy agonists, and promoted by autophagy inhibitors. PD-L1 has a negative regulatory effect on sepsis. It can reduce the expression of PD-L1 molecule in sepsis by targeting autophagy, so as to improve sepsis.

Patterns and prognostic relevance of PD-1 and PD-L1 expression in colorectal carcinoma

Differential expression of PD-L1 and IDO1 in association with the immune microenvironment in resected lung adenocarcinomas

BackgroundProgrammed death ligand-1 (PD-L1) has been identified as a factor associated with poor prognosis in a range of cancers, and was reported to be mainly induced by PTEN loss in gliomas. However, the clinical effect of PD-L1 and its regulation by PTEN has not yet been determined in colorectal cancer (CRC). In the present study, we verified the regulation of PTEN on PD-L1 and further determined the effect of PTEN on the correlation between PD-L1 expression and clinical parameters in CRC.Methods/ResultsRNA interference approach was used to down-regulate PTEN expression in SW480, SW620 and HCT116 cells. It was showed that PD-L1 protein, but not mRNA, was significantly increased in cells transfected with siRNA PTEN compared with the negative control. Moreover, the capacity of PTEN to regulate PD-L1 expression was not obviously affected by IFN-γ, the main inducer of PD-L1. Tissue microarray immunohistochemistry was used to detect PD-L1 and PTEN in 404 CRC patient samples. Overexpression of PD-L1 was significantly correlated with distant metastasis (P<0.001), TNM stage (P<0.01), metastatic progression (P<0.01) and PTEN expression (P<0.001). Univariate analysis revealed that patients with high PD-L1 expression had a poor overall survival (P<0.001). However, multivariate analysis did not support PD-L1 as an independent prognostic factor (P = 0.548). Univariate (P<0.001) and multivariate survival (P<0.001) analysis of 310 located CRC patients revealed that high level of PD-L1 expression was associated with increased risks of metastatic progression. Furthermore, the clinical effect of PD-L1 on CRC was not statistically significant in a subset of 39 patients with no PTEN expression (distant metastasis: P = 0.102; TNM stage: P = 0.634, overall survival: P = 0.482).ConclusionsPD-L1 can be used to identify CRC patients with high risk of metastasis and poor prognosis. This clinical manifestation may be partly associated with PTEN expression.

Placental trophoblasts contribute to regulatory T (Treg) function via the programmed cell death-1 (PD-1)/PD-1 ligand 1 (PD-L1) pathway during normal pregnancy. Decreased expression of PD-L1 in trophoblasts was closely associated with Treg deficiency in the development of pregnancy failure. Thus, targeting PD-L1 might be a novel therapy to prevent pregnancy loss. However, the mechanisms for modulating the expression of PD-L1 in trophoblasts are an enigma. The proportion of decidual Treg cells, and the profile of decidual macrophages (DMs) sampled from women with normal pregnancy (NP) and recurrent miscarriage (RM) were evaluated by flow cytometry. The expression of Yin and Yang 1 protein (YY1) and PD-L1 in human villous were measured by Immunohistochemistry (IHC), qRT-PCR and western blot. The determination of soluble PD-L1 (sPD-L1) in serum from NP and RM, and trophoblast conditioned media (TCM) was performed by the PD-L1 SimpleStep ELISA kit. Knockdown of YY1 was processed in the human trophoblast derived cell lines, HTR-8 and Bewo, with siYY1 transfection. Peripheral naïve CD4+ T cells were isolated from women with NP for the in vitro culture. The percentages of Treg cells differentiated from peripheral naïve CD4+ T cells were measured by flow cytometry. The interaction between YY1 and CD274 was proved by CHIP. The expression of inducible nitric oxide synthase (iNOS) in decidua was evaluated by IHC. The level of NO in serum from women with NP and RM was determined by the Griess reagent system. The effects of NO on YY1 were determined by the in vitro culture of HTR-8 cells with the NO donor, SNAP. The in vivo model comprising twelve pregnant mice and underwent different treatment. The percentages of Treg cells in murine uterus were measured by flow cytometry. Similarly, Western blot and IHC were performed to determine the expression of YY1 and PD-L1 in murine placenta. Decreased expression of YY1 and PD-L1 in trophoblasts and lower proportion of decidual Treg cells were observed in patients with RM. Knockdown of YY1 contributes to a lower expression of YY1 and PD-L1. Soluble PD-L1 in the supernatant from HTR-8 cells was also decreased with siYY1 administration. Lower Treg differentiation was observed in the presence of supernatant from HTR-8 cells treated with siYY1. CHIP analysis revealed that endogenous YY1 directly occupied the promoter region of the CD274 (PD-L1) gene. Accompanied with increased M1 DMs, higher NO was observed in serum sampled from patients with RM. In the presence of Reduced expression of YY1 and PD-L1 was observed in HTR-8 cells with the treatment of SNAP. Furthermore, less Treg differentiation was observed with SNAP treated TCM. Moreover, our in vivo data found that YY1 deficiency was associated with decreased PD-L1, which further resulting in less Treg differentiation and Treg deficiency at the maternal-fetal interface and increased embryo loss. Our work found the modulatory capacity of YY1 on PD-L1 in trophoblasts during early pregnancy. Furthermore, reduced YY1 was supposed resulting from higher levels of NO produced from the M1 DMs in RM.

H3K27me3-mediated regulation of PD-L1 expression in triple-negative breast cancer (TNBC).

Simple SummaryFor non-small-cell lung cancer (NSCLC) patients undergoing immunotherapy blocking the PD-1/PD-L1 interaction, the cancer cell PD-L1 expression level is a determinant of treatment efficiency. This study was conducted to determine whether PD-L1 DNA methylation regulates and can predict PD-L1 expression in NSCLC. Tumor biopsies and cell lines were analyzed for PD-L1 DNA methylation, mRNA expression, and protein expression. CRISPR-Cas9 and dCas9 fusions with TET1 and DNMT3A were used to change the PD-L1 DNA methylation levels. In this study, we found that the PD-L1 DNA methylation status functionally influences its expression. However, although methylation can be inversely correlated with the expression of PD-L1 in NSCLC lines, this association is not strong in NSCLC tumor samples. The fact that PD-L1 DNA methylation status does not inevitably mirror the expression level is important for future attempts to improve the effectiveness of PD-1/PD-L1 immunotherapy in NSCLC.Immunotherapy targeting the interaction between programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) is a treatment option for patients with non-small-cell lung cancer (NSCLC). The expression of PD-L1 by the NSCLC cells determines treatment effectiveness, but the relationship between PD-L1 DNA methylation and expression has not been clearly described. We investigated PD-L1 DNA methylation, mRNA expression, and protein expression in NSCLC cell lines and tumor biopsies. We used clustered regularly interspaced short palindromic repeats-associated protein 9 (CRISPR-Cas9) to modify PD-L1 genetic contexts and endonuclease deficient Cas9 (dCas9) fusions with ten-eleven translocation methylcytosine dioxygenase 1 (TET1) and DNA (cytosine-5)-methyltransferase 3A (DNMT3A) to manipulate PD-L1 DNA methylation. In NSCLC cell lines, we identified specific PD-L1 CpG sites with methylation levels inversely correlated with PD-L1 mRNA expression. However, inducing PD-L1 mRNA expression with interferon-γ did not decrease the methylation level for these CpG sites, and using CRISPR-Cas9, we found that the CpG sites did not directly confer a negative regulation. dCas9-TET1 and dCas9-DNMT3A could induce PD-L1 hypo- and hyper-methylation, respectively, with the latter conferring a decrease in expression showing the functional impact of methylation. In NSCLC biopsies, the inverse correlation between the methylation and expression of PD-L1 was weak. We conclude that there is a regulatory link between PD-L1 DNA methylation and expression. However, since these measures are weakly associated, this study highlights the need for further research before PD-L1 DNA methylation can be implemented as a biomarker and drug target for measures to improve the effectiveness of PD-1/PD-L1 immunotherapy in NSCLC.

Programmed cell death protein 1 (PD-1)/ programmed cell death ligand 1(PD-L1) axis is associated with immune tolerance via inhibition of T cell activation. The aim of this study was to clarify the significance of PD-1 and PD-L1 expressions and analyze the relationships between PD-1, PD-L1, transforming growth factor-β (TGF-β) and Forkhead box P3 (Foxp3) expressions in colorectal cancer (CRC). A total of 116 patients who underwent curative colectomy for stage II/III CRC were included in the study. PD-1, PD-L1, TGF-β, and Foxp3 expressions were examined by immunohistochemistry and related to prognostic factors by Kaplan-Meier. PD-1 expression was correlated with PD-L1, TGF-β, and Foxp3 expressions. Overall survival rates were significantly poorer in the PD-1 and PD-L1-positive groups. Multivariate analysis showed that PD-L1-positive is an independent risk factor. Disease-free survival (DFS) was tended in the PD-L1-positive group. The group with double-positive expression had significantly poorer prognosis. PD-1 and PD-L1 expressions were associated with a poor prognosis and correlated with TGF-β and Foxp3 expressions in patients with CRC.

Background: Upregulation of Programmed Death-Ligand 1 (PD-L1) in tumor cells results in the deactivation of cytotoxic T cells in the tumor microenvironment and development of tolerance to the malignant cells. We aimed to investigate the role of PD-L1 expression in early stage breast cancer and its correlation with tumor characteristics as well as assess the relationship between PD-L1 membrane protein and gene expression. Methods: For this single center, retrospective study, women (age &amp;gt;18 years) with early stage breast cancer diagnosed between January 2005 and December 2005 were enrolled. Key inclusion criteria for enrollment were pathologic diagnosis of DCIS or invasive ductal/lobular carcinoma, stage 0-2, with local resection done in 2005. Patients had to have adequate formalin-fixed paraffin-embedded tumor specimens for PD-L1 testing. We hypothesized that higher levels of PD-L1 expression correlates with more aggressive disease and worse prognosis. We used histopathological analysis, medical chart review, and PD-L1 expression via immunohistochemistry (IHC) and reverse transcription polymerase chain reaction (RT-PCR) for data analysis. Chi Square and one way ANOVA analyses were used to compare clinical and pathological characteristics of patients with high and low PD-L1 expression. Results In 2005, 368 women were diagnosed with breast cancer at Providence-Providence Park Hospital of which 31 pathological specimens were obtained for exploratory analysis. PD-L1 protein expression was determined to be positive if more than 1% of the tumor cells showed partial or complete membrane staining for PD-L1 by IHC. All patients with DCIS (n=7) were negative for PDL-1 expression although 3 showed gene expression by PCR. After excluding the DCIS specimens, 17% (4/24) of early stage breast cancer was found to express PD-L1 protein. Seven of 24 specimens (excluding DCIS) were positive for PD-L1 RNA by RT-PCR. There was no relationship between PD-L1 protein and mRNA expression (p=0.552). 75% of the PD-L1 positive specimens by IHC were also ER positive although this was not statistically significant (p=0.312). There was a trend toward larger tumors for those expressing PD-L1 on the cell surface (mean size of 2.7 cm vs 1.7 cm, p= 0.07). All the PD-L1 positive specimens had increased lymphocyte infiltration, although no statistical significance was observed. At 10 years from initial diagnosis, all-cause mortality rate was 29% (7/24). The rate of death in PD-L1 positive patients was 2/4 (50%) compared to 5/20 (25%) in PD-L1 negative group. Conclusion: Expression of PD-L1 in early stage breast cancer could be an important indicator for more aggressive disease and supports investigating checkpoint inhibitors in this population. Further investigation is needed to determine its applicability in clinical decisions and effects on treatment. Citation Format: Hadeel Assad, Juan Cattoni, Subramanyeswara Arekapudi, Nancy Jackson, Hugo Macchi Cattoni, Sherri Motahari, Hema Govil, Anibal Drelichman. Correlation between PD-L1 expression and tumor clinicopathologic characteristics in early stage breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5006. doi:10.1158/1538-7445.AM2017-5006

Programmed death ligand 1 (PD-L1) plays a significant role in colorectal tumorigenesis through induction of regulatory T cells (Tregs) and suppression of antitumor immunity. Furthermore, microRNAs (miRNAs) as the posttranscriptional regulators of gene expression show considerable promise as a therapeutic target for colorectal cancer (CRC) treatment. Considering this, in vitro effects of miRNA-124 (miR-124-3p) on CRC cell tumorigenesis and Tregs differentiation via targeting PD-L1were investigated in the current study. Functional analysis showed that miR-124 is significantly downregulated in CRC tissues as compared with marginal normal samples (p < .0001), and its downregulation was negatively correlated with PD-L1 expression. Moreover, a specific region in PD-L1 3'-untranslated region was predicted as the miR-124 target and validated using the luciferase assay. Further investigation showed that transfection of HT29 and SW480 cells with miR-124 mimics significantly reduced PD-L1 mRNA, protein, and cell surface expression, and inhibited Tregs in coculture models via modulating interleukin[IL]-10, IL-2, tumor necrosis factor α, transforming growth factor beta, and interferon gamma expression levels. Besides, miR-124 overexpression decreased CRC cell proliferation and arrested cell cycle at the G1 phase through downregulation of c-Myc and induced apoptosis in CRC cells via upregulation of both intrinsic and extrinsic pathways. Also, miR-124 exogenous overexpression could reduce colony and spheroid formation ability of CRC cells via downregulating CD44 mRNA expression. miR-124 also diminished MMP-9 expression and subsequently suppressed cell migration and invasion. We also illustrated that STAT3 signaling was repressed by miR-124 in CRC cells. Taken together, our findings imply that considering the involvement of miR-124 in the regulation of PD-L1 through colorectal tumorigenesis and its remarkable antitumor effects, this miRNA could be regarded as the promising target for the development of therapeutic approaches for colorectal cancer.

BACKGROUNDAnti-programmed death therapy has thrust immunotherapy into the spotlight. However, such therapy has a modest response in hepatocellular carcinoma (HCC). Epigenetic immunomodulation is a suggestive combinatorial therapy with immune checkpoint blockade. Non-coding ribonucleic acid (ncRNA) driven regulation is a major mechanism of epigenetic modulation. Given the wide range of ncRNAs that co-opt in programmed cell-death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) regulation, and based on the literature, we hypothesized that miR-155-5p, miR-194-5p and long non-coding RNAs (lncRNAs) X-inactive specific transcript (XIST) and MALAT-1 are involved in a regulatory upstream pathway for PD-1/PD-L1. Recently, nutraceutical therapeutics in cancers have received increasing attention. Thus, it is interesting to study the impact of oleuropein on the respective study key players.AIMTo explore potential upstream regulatory ncRNAs for the immune checkpoint PD-1/PD-L1.METHODSBioinformatics tools including microrna.org and lnCeDB software were adopted to detect targeting of miR-155-5p, miR-194-5p and lncRNAs XIST and MALAT-1 to PD-L1 mRNA, respectively. In addition, Diana tool was used to predict targeting of both aforementioned miRNAs to lncRNAs XIST and MALAT-1. HCC and normal tissue samples were collected for scanning of PD-L1, XIST and MALAT-1 expression. To study the interaction among miR-155-5p, miR-194-5p, lncRNAs XIST and MALAT-1, as well as PD-L1 mRNA, a series of transfections of the Huh-7 cell line was carried out. RESULTSBioinformatics software predicted that miR-155-5p and miR-194-5p can target PD-L1, MALAT-1 and XIST. MALAT-1 and XIST were predicted to target PD-L1 mRNA. PD-L1 and XIST were significantly upregulated in 23 HCC biopsies compared to healthy controls; however, MALAT-1 was barely detected. MiR-194 induced expression elevated the expression of PD-L1, XIST and MALAT-1. However, overexpression of miR-155-5p induced the upregulation of PD-L1 and XIST, while it had a negative impact on MALAT-1 expression. Knockdown of XIST did have an impact on PD-L1 expression; however, following knockdown of the negative regulator of X-inactive specific transcript (TSIX), PD-L1 expression was elevated, and abolished MALAT-1 activity. Upon co-transfection of miR-194-5p with siMALAT-1, PD-L1 expression was elevated. Co-transfection of miR-194-5p with siXIST did not have an impact on PD-L1 expression. Upon co-transfection of miR-194 with siTSIX, PD-L1 expression was upregulated. Interestingly, the same PD-L1 expression pattern was observed following miR-155-5p co-transfections. Oleuropein treatment of Huh-7 cells reduced the expression profile of PD-L1, XIST, and miR-155-5p, upregulated the expression of miR-194-5p and had no significant impact on the MALAT-1 expression profile.CONCLUSIONThis study reported a novel finding revealing that opposing acting miRNAs in HCC, have the same impact on PD-1/PD-L1 immune checkpoint by sharing a common signaling pathway.