MicroRNA-34a enhances T cell activation by targeting diacylglycerol kinase ζ

Epigenetics in T-cell driven inflammation and cancer

For decades, scientists have been investigating how processes such as gene expression, stem cell plasticity, and cell differentiation can be modulated. The discovery of epigenetics helped unravel these processes and enabled the identification of major underlying mechanisms that, for example, are central for T cell maturation. T cells go through various stages in their development evolving from progenitor cells into double positive CD4/CD8 T cells that finally leave the thymus as naïve T cells. One major mechanism driving T cell maturation is the modulation of gene activity by temporally sequenced transcription of spatially exposed gene loci. DNA methylation, demethylation, and acetylation are key processes that enable a sequenced gene expression required for T cell differentiation. In vivo, differentiated T cells are subjected to enormous pressures originating from the microenvironment. Signals from this environment, particularly from an inflammatory or a tumor microenvironment, can push T cells to differentiate into specific effector and memory T cells, and even prompt T cells to adopt a state of dysfunctional exhaustion, en route of an epigenetically controlled mechanism. Fundamentals of these processes will be discussed in this review highlighting potential therapeutic interventions, in particular those beneficial to revive exhausted T cells.

Diacylglycerol kinases: A look into the future of immunotherapy

Cancer still represents the second leading cause of death right after cardiovascular diseases. According to the World Health Organization (WHO), cancer provoked around 10 million deaths in 2020, with lung and colon tumors accounting for the deadliest forms of cancer. As tumor cells become resistant to traditional therapeutic approaches, immunotherapy has emerged as a novel strategy for tumor control. T lymphocytes are key players in immune responses against tumors. Immunosurveillance allows identification, targeting and later killing of cancerous cells. Nevertheless, tumors evolve through different strategies to evade the immune response and spread in a process called metastasis. The ineffectiveness of traditional strategies to control tumor growth and expansion has led to novel approaches considering modulation of T cell activation and effector functions. Program death receptor 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) showed promising results in the early 90s and nowadays are still being exploited together with other drugs for several cancer types. Other negative regulators of T cell activation are diacylglycerol kinases (DGKs) a family of enzymes that catalyze the conversion of diacylglycerol (DAG) into phosphatidic acid (PA). In T cells, DGKα and DGKζ limit the PLCγ/Ras/ERK axis thus attenuating DAG mediated signaling and T cell effector functions. Upregulation of either of both isoforms results in impaired Ras activation and anergy induction, whereas germline knockdown mice showed enhanced antitumor properties and more effective immune responses against pathogens. Here we review the mechanisms used by DGKs to ameliorate T cell activation and how inhibition could be used to reinvigorate T cell functions in cancer context. A better knowledge of the molecular mechanisms involved upon T cell activation will help to improve current therapies with DAG promoting agents.

The Roles of MiRNAs (MicroRNAs) in Melanoma Immunotherapy

Melanoma is the most aggressive form of skin cancer, characterized by life-threatening and rapidly spreading progression. Traditional targeted therapy can alleviate tumors by inactivating hyperactive kinases such as BRAF or MEK but inevitably encounters drug resistance. The advent of immunotherapy has revolutionized melanoma treatment and significantly improved the prognosis of melanoma patients. MicroRNAs (miRNAs) are intricately involved in innate and adaptive immunity and are implicated in melanoma immunotherapy. This systematic review describes the roles of miRNAs in regulating the functions of immune cells in skin and melanoma, as well as the involvement of miRNAs in pharmacology including the effect, resistance and immune-related adverse events of checkpoint inhibitors such as PD-1 and CTLA-4 inhibitors, which are used for treating cutaneous, uveal and mucosal melanoma. The expressions and functions of miRNAs in immunotherapy employing tumor-infiltrating lymphocytes and Toll-like receptor 9 agonists are also discussed. The prospect of innovative therapeutic strategies such as the combined administration of miRNAs and immune checkpoint inhibitors and the nanotechnology-based delivery of miRNAs are also provided. A comprehensive understanding of the interplay between miRNAs and immunotherapy is crucial for the discovery of reliable biomarkers and for the development of novel miRNA-based therapeutics against melanoma.

Prenatal Cadmium Exposure Alters Proliferation in Mouse CD4+ T Cells via LncRNA Snhg7

Objective

Prenatal cadmium (Cd) exposure leads to immunotoxic phenotypes in the offspring affecting coding and non-coding genes. Recent studies have shown that long non-coding RNAs (lncRNAs) are integral to T cell regulation. Here, we investigated the role of long non-coding RNA small nucleolar RNA host gene 7 (lncSnhg7) in T cell proliferation.

Methods

RNA sequencing was used to analyze the expression of lncRNAs in splenic CD4+ T cells with and without CD3/CD28 stimulation. Next, T cells isolated from offspring exposed to control or Cd water throughout mating and gestation were analyzed with and without stimulation with anti-CD3/CD28 beads. Quantitative qPCR and western blotting were used to detect RNA and protein levels of specific genes. Overexpression of a miR-34a mimic was achieved using nucleofection. Apoptosis was measured using flow cytometry and luminescence assays. Flow cytometry was also used to measure T cell proliferation in culture. Finally, lncSnhg7 was knocked down in splenic CD4+ T cells with lentivirus to assess its effect on proliferation.

Results

We identified 23 lncRNAs that were differentially expressed in stimulated versus unstimulated T cells, including lncSnhg7. LncSnhg7 and a downstream protein, GALNT7, are upregulated in T cells from offspring exposed to Cd during gestation. Overexpression of miR-34a, a regulator of lncSnhg7 and GALNT7, suppresses GALNT7 protein levels in primary T cells, but not in a mouse T lymphocyte cell line. The T cells isolated from Cd-exposed offspring exhibit increased proliferation after activation in vitro, but Treg suppression and CD4+ T cell apoptosis are not affected by prenatal Cd exposure. Knockdown on lncSnhg7 inhibits proliferation of CD4+ T cells.

Conclusion

Prenatal Cd exposure alters the expression of lncRNAs during T cell activation. The induction of lncSnhg7 is enhanced in splenic T cells from Cd offspring resulting in the upregulation of GALNT7 protein and increased proliferation following activation. miR-34a overexpression decreased GALNT7 expression and knockdown of lncSnhg7 inhibited proliferation suggesting that the lncSnhg7/miR-34a/GALNT7 is an important pathway in primary CD4+ T cells. These data highlight the need to understand the consequences of environmental exposures on lncRNA functions in non-cancerous cells as well as the effects in utero.

Lipid Metabolism in the Development and Progression of Vascular Cognitive Impairment: A Systematic Review

Background: Vascular cognitive impairment (VCI) is a major public health problem. The current diagnosis of VCI is made based on the assessment of clinical symptoms and neuropsychological measurements, and is supported by neuroimaging. These methods are both time-consuming and expensive, which leads to needs for alternative biomarkers for VCI. Metabolomics is an emerging and powerful tool to discover of new biomarkers of disease, which can investigate variations in different metabolic processes such as lipid, since the brain is highly enriched in lipids and that lipid changes may lead to pathology in the brain. Vascular cognitive impairment is vulnerable to the disturbance of lipid metabolism. Furthermore, blood samples, which could be identified as reliable clinical biomarkers are relatively convenient to obtain and provide a non-invasive assessment. Therefore, our study aims to understand whether peripheral lipid biomarkers can be used as diagnostic biomarkers and monitor the progression of VCI.

Methods: We systematically searched the PubMed, Embase, CNKI, and VIP databases to find VCI and lipid metabolism in reports from inception through February 2021. Studies meeting the following criteria were eligible: (1) original studies in humans; (2) lipid metabolites in blood; (3) reports of VCI.

Results: Through our review, nine original articles were eligible. Blood-based metabolites that might be potential biomarkers were identified. Most of them including PC, PE, Cers, and ChEs were significantly lower, while elevation of FAs and DGs were associated with VCI. Most importantly, these blood-based metabolites might be proposed as potential biomarkers for VCI, which provides direction for further validation.

Discussion and Conclusion: To the best of our knowledge, this is the first systemic review concerning the relationship of lipid metabolism and VCI. It identifies potential biomarkers and provides insights into the disease pathobiology. However, more advanced studies and researches on a lipidomic platform must be done to understand the exact pathology behind and identify potential lipid biomarkers, which might help achieve the goal of discovering novel therapeutics.

Association of microRNA-34a rs2666433 (A/G) Variant with Systemic Lupus Erythematosus in Female Patients: A Case-Control Study

Several microRNAs (miRNAs) are associated with autoimmune disease susceptibility and phenotype, including systemic lupus erythematosus (SLE). We aimed to explore for the first time the role of the miRNA-34a gene (MIR34A) rs2666433A > G variant in SLE risk and severity. A total of 163 adult patients with SLE and matched controls were recruited. Real-Time allelic discrimination PCR was applied for genotyping. Correlation with disease activity and clinic-laboratory data was done. The rs2666433 variant conferred protection against SLE development under heterozygous [A/G vs. G/G; OR = 0.57, 95%CI = 0.34-0.95], homozygous [A/A vs. G/G; OR = 0.52, 95%CI = 0.29-0.94], dominant [A/G + A/A vs. GG; OR = 0.55, 95%CI = 0.35-0.88], and log-additive [OR = 0.71, 95%CI = 0.53-0.95] models. Data stratification by sex revealed a significant association with SLE development in female participants under heterozygous/homozygous models (p-interaction = 0.004). There was no clear demarcation between SLE patients carrying different genotypes regarding the disease activity index or patients stratified according to lupus nephritis. Enrichment analysis confirmed the implication of MIR34A in the SLE pathway by targeting several genes related to SLE etiopathology. In conclusion, although the MIR34A rs2666433 variant conferred protection against developing SLE disease in the study population, it showed no association with disease activity. Replication studies in other populations are warranted.

Differential Leukocyte MicroRNA Responses Following Pan T Cell, Allorecognition and Allosecretome-Based Therapeutic Activation

Effective immunomodulation of T-cell responses is critical in treating both autoimmune diseases and cancer. Our previous studies have demonstrated that secretomes derived from control or methoxypolyethylene glycol mixed lymphocyte alloactivation assays exerted potent immunomodulatory activity that was mediated by microRNAs (miRNA). The immunomodulatory effects of biomanufactured miRNA-based allo-secretome therapeutics (SYN, TA1, IA1 and IA2) were compared to Pan T-cell activators (PHA and anti-CD3/CD28) and lymphocyte alloactivation. The differential effects of these activation strategies on resting peripheral blood mononuclear cells (PBMC) were assessed via T-cell proliferation, subset analysis and miRNA expression profiles. Mitogen-induced PBMC proliferation (> 85%) significantly exceeded that arising from either allostimulation (~ 30%) or the pro-inflammatory IA1 secretome product (~ 12%). Consequent to stimulation, the ratio of CD4 to CD8 cells of the resting PBMC (CD4:CD8; 1.7 ± 0.1) decreased in the Pan T cell, allrecognition and IA1 activated cells (averages of 1.1 ± 0.2; 1.2 ± 0.1 and 1.0 ± 0.1). These changes arose consequent to the expansion of both CD4⁺CD8⁺ and CD4^–CD8^– populations as well as the shrinkage of the CD4 subset and the expansion of the CD8 T cells. Importantly, these activation strategies induced vastly different miRNA expression profiles which were associated with significant differences in cellular differentiation and biological function. These findings support the concept that the “differential patterns of miRNA expression” regulate the biologic immune response in a “lock and key” manner. The biomanufacturing of miRNA-enriched secretome biotherapeutics may be a successful therapeutic approach for the systemic treatment of autoimmune diseases (TA1) and cancer (IA1).

Regulatory roles of MicroRNA in shaping T cell function, differentiation and polarization

T lymphocytes are an integral component of adaptive immunity with pleotropic effector functions. Impairment of T cell activity is implicated in various immune pathologies including autoimmune diseases, AIDS, carcinogenesis, and periodontitis. Evidently, T cell differentiation and function are under robust regulation by various endogenous factors that orchestrate underlying molecular pathways. MicroRNAs (miRNA) are a class of noncoding, regulatory RNAs that post-transcriptionally control multiple mRNA targets by sequence-specific interaction. In this article, we will review the recent progress in our understanding of miRNA-gene networks that are uniquely required by specific T cell effector functions and provide miRNA-mediated mechanisms that govern the fate of T cells. A subset of miRNAs may act in a synergistic or antagonistic manner to exert functional suppression of genes and regulate pathways that control T cell activation and differentiation. Significance of T cell-specific miRNAs and their dysregulation in immune-mediated diseases is discussed. Exosome-mediated horizontal transfer of miRNAs from antigen presenting cells (APCs) to T cells and from one T cell to another T cell subset and their impact on recipient cell functions is summarized.

Plasma lipidome is dysregulated in Alzheimer's disease and is associated with disease risk genes

Lipidomics research could provide insights of pathobiological mechanisms in Alzheimer's disease. This study explores a battery of plasma lipids that can differentiate Alzheimer's disease (AD) patients from healthy controls and determines whether lipid profiles correlate with genetic risk for AD. AD plasma samples were collected from the Sydney Memory and Ageing Study (MAS) Sydney, Australia (aged range 75-97 years; 51.2% male). Untargeted lipidomics analysis was performed by liquid chromatography coupled-mass spectrometry (LC-MS/MS). We found that several lipid species from nine lipid classes, particularly sphingomyelins (SMs), cholesterol esters (ChEs), phosphatidylcholines (PCs), phosphatidylethanolamines (PIs), phosphatidylinositols (PIs), and triglycerides (TGs) are dysregulated in AD patients and may help discriminate them from healthy controls. However, when the lipid species were grouped together into lipid subgroups, only the DG group was significantly higher in AD. ChEs, SMs, and TGs resulted in good classification accuracy using the Glmnet algorithm (elastic net penalization for the generalized linear model [glm]) with more than 80% AUC. In general, group lipids and the lipid subclasses LPC and PE had less classification accuracy compared to the other subclasses. We also found significant increases in SMs, PIs, and the LPE/PE ratio in human U251 astroglioma cell lines exposed to pathophysiological concentrations of oligomeric Aβ₄₂. This suggests that oligomeric Aβ₄₂ plays a contributory, if not causal role, in mediating changes in lipid profiles in AD that can be detected in the periphery. In addition, we evaluated the association of plasma lipid profiles with AD-related single nucleotide polymorphisms (SNPs) and polygenic risk scores (PRS) of AD. We found that FERMT2 and MS4A6A showed a significantly differential association with lipids in all lipid classes across disease and control groups. ABCA7 had a differential association with more than half of the DG lipids (52.63%) and PI lipids (57.14%), respectively. Additionally, 43.4% of lipids in the SM class were differentially associated with CLU. More than 30% of lipids in ChE, PE, and TG classes had differential associations with separate genes (ChE-PICALM, SLC24A4, and SORL1; PE-CLU and CR1; TG-BINI) between AD and control group. These data may provide renewed insights into the pathobiology of AD and the feasibility of identifying individuals with greater AD risk.

MicroRNA-34a: Potent Tumor Suppressor, Cancer Stem Cell Inhibitor, and Potential Anticancer Therapeutic

Overwhelming evidence indicates that virtually all treatment-naive tumors contain a subpopulation of cancer cells that possess some stem cell traits and properties and are operationally defined as cancer cell stem cells (CSCs). CSCs manifest inherent heterogeneity in that they may exist in an epithelial and proliferative state or a mesenchymal non-proliferative and invasive state. Spontaneous tumor progression, therapeutic treatments, and (epi)genetic mutations may also induce plasticity in non-CSCs and reprogram them into stem-like cancer cells. Intrinsic cancer cell heterogeneity and induced cancer cell plasticity, constantly and dynamically, generate a pool of CSC subpopulations with varying levels of epigenomic stability and stemness. Despite the dynamic and transient nature of CSCs, they play fundamental roles in mediating therapy resistance and tumor relapse. It is now clear that the stemness of CSCs is coordinately regulated by genetic factors and epigenetic mechanisms. Here, in this perspective, we first provide a brief updated overview of CSCs. We then focus on microRNA-34a (miR-34a), a tumor-suppressive microRNA (miRNA) devoid in many CSCs and advanced tumors. Being a member of the miR-34 family, miR-34a was identified as a p53 target in 2007. It is a bona fide tumor suppressor, and its expression is dysregulated and downregulated in various human cancers. By targeting stemness factors such as NOTCH, MYC, BCL-2, and CD44, miR-34a epigenetically and negatively regulates the functional properties of CSCs. We shall briefly discuss potential reasons behind the failure of the first-in-class clinical trial of MRX34, a liposomal miR-34a mimic. Finally, we offer several clinical settings where miR-34a can potentially be deployed to therapeutically target CSCs and advanced, therapy-resistant, and p53-mutant tumors in order to overcome therapy resistance and curb tumor relapse.

Regulatory and immunomodulatory role of miR-34a in T cell immunity

miRNAs are a class of non-coding RNAs and very conserve molecules that negatively regulate the expression of many genes by targeting the 3' UTR of mRNAs. miRNAs are involved in the modulation of T-cell biology during the earliest and last stages and key controllers of T-cell differentiation and function. The miR-34a, as a major hub of the regulatory network of T cells, plays an important role in T cell activation. miR-34a is widely expressed in immune cells (dendritic cells, macrophages, mast cells, B cells, and T cells) and regulates their development, function, and survival. This miRNA, by targeting over 30 genes across different cellular pathways controls immune response. miR-34a expression is controlled by p53 in transcription level. As well as, miR-34a by activating dendritic cells mediates innate immune response and increases tumor-infiltrating CD8 expression T lymphocytes. In various types of cancers and autoimmune diseases, miR-34a can regulate T cell function and become a possible significant target of microRNA-based therapy. Therefore, in this review, we focus on miR-34a-related regulatory mechanisms in T cell function and understanding mechanisms and molecules involved in this network.

Negative control of diacylglycerol kinase ζ-mediated inhibition of T cell receptor signaling by nuclear sequestration in mice

Diacylglycerol kinases (DGKs) play important roles in restraining diacylglycerol (DAG)-mediated signaling. Within the DGK family, the ζ isoform appears to be the most important isoform in T cells for controlling their development and function. DGKζ has been demonstrated to regulate T cell maturation, activation, anergy, effector/memory differentiation, defense against microbial infection, and antitumor immunity. Given its critical functions, DGKζ function should be tightly regulated to ensure proper signal transduction; however, mechanisms that control DGKζ function are still poorly understood. We report here that DGKζ dynamically translocates from the cytosol into the nuclei in T cells after TCR stimulation. In mice, DGKζ mutant defective in nuclear localization displayed enhanced ability to inhibit TCR-induced DAG-mediated signaling in primary T cells, maturation of conventional αβT and iNKT cells, and activation of peripheral T cells compared with WT DGKζ. Our study reveals for the first time nuclear sequestration of DGKζ as a negative control mechanism to spatially restrain it from terminating DAG mediated signaling in T cells. Our data suggest that manipulation of DGKζ nucleus-cytosol shuttling as a novel strategy to modulate DGKζ activity and immune responses for treatment of autoimmune diseases and cancer.

Plasma lipidomic biomarker analysis reveals distinct lipid changes in vascular dementia

Vascular dementia (VaD) is a complex neurocognitive disorder secondary to a variety of cerebrovascular lesions. Numerous studies have shown that lipid metabolism is involved in the pathobiology of the disease. We examined the plasma lipid profiles in VaD, with the expectation of identifying reliable lipid biomarkers for VaD. 49 VaD patients and 48 healthy controls were recruited from Bankstown-Lidcombe Hospital in Sydney, Australia. Lipids were extracted by single phase 1-butanol/methanol, and untargeted analysis was performed by liquid chromatography coupled-mass spectrometry (LC–MS/MS). Univariate analysis of variance was used to examine the differences in lipid classes and individual lipids between VaD and control groups. In an independent sample of 161 subjects from the Older Australian Twins Study (OATS), elastic net penalization for the generalized linear model (Glmnet) and Random Forest were applied to the lipid levels to subcategorise the sample into vascular cognitive impairment and controls. Most lipids belonging to the classes of ceramides (Cer), cholesterol esters (ChE) and phospholipids were significantly lower in VaD plasma, while glycerides were elevated compared to controls. Levels of ChE, Cer and the two lipid classes together achieved the best accuracy in discriminating VaD from controls, with more than 80% accuracy. The probable VaD group in the OATS sample predicted by the lipid levels showed greater impairment in most cognitive domains, especially attention and processing speed and executive function from controls but did not differ in white matter hyperintensities and DTI measures. As a conclusion, plasma lipids levels, in particular Cer and ChE, are abnormal in VaD and may help discriminate them from healthy controls. Understanding the basis of these differences may provide insights into the pathobiology of VaD.

Phase 1 study of MRX34, a liposomal miR-34a mimic, in patients with advanced solid tumours

BACKGROUND

In this first-in-human, Phase 1 study of a microRNA-based cancer therapy, the recommended Phase 2 dose (RP2D) of MRX34, a liposomal mimic of microRNA-34a (miR-34a), was determined and evaluated in patients with advanced solid tumours.

METHODS

Adults with various solid tumours refractory to standard treatments were enrolled in 3 + 3 dose-escalation cohorts and, following RP2D determination, expansion cohorts. MRX34, with oral dexamethasone premedication, was given intravenously daily for 5 days in 3-week cycles.

RESULTS

Common all-cause adverse events observed in 85 patients enrolled included fever (% all grade/G3: 72/4), chills (53/14), fatigue (51/9), back/neck pain (36/5), nausea (36/1) and dyspnoea (25/4). The RP2D was 70 mg/m2 for hepatocellular carcinoma (HCC) and 93 mg/m2 for non-HCC cancers. Pharmacodynamic results showed delivery of miR-34a to tumours, and dose-dependent modulation of target gene expression in white blood cells. Three patients had PRs and 16 had SD lasting ≥4 cycles (median, 19 weeks, range, 11-55).

CONCLUSION

MRX34 treatment with dexamethasone premedication demonstrated a manageable toxicity profile in most patients and some clinical activity. Although the trial was closed early due to serious immune-mediated AEs that resulted in four patient deaths, dose-dependent modulation of relevant target genes provides proof-of-concept for miRNA-based cancer therapy.

CLINICAL TRIAL REGISTRATION

NCT01829971.

Beyond the Cell Surface: Targeting Intracellular Negative Regulators to Enhance T cell Anti-Tumor Activity

It is well established that extracellular proteins that negatively regulate T cell function, such as Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA-4) and Programmed Cell Death protein 1 (PD-1), can be effectively targeted to enhance cancer immunotherapies and Chimeric Antigen Receptor T cells (CAR-T cells). Intracellular proteins that inhibit T cell receptor (TCR) signal transduction, though less well studied, are also potentially useful therapeutic targets to enhance T cell activity against tumor. Four major classes of enzymes that attenuate TCR signaling include E3 ubiquitin kinases such as the Casitas B-lineage lymphoma proteins (Cbl-b and c-Cbl), and Itchy (Itch), inhibitory tyrosine phosphatases, such as Src homology region 2 domain-containing phosphatases (SHP-1 and SHP-2), inhibitory protein kinases, such as C-terminal Src kinase (Csk), and inhibitory lipid kinases such as Src homology 2 (SH2) domain-containing inositol polyphosphate 5-phosphatase (SHIP) and Diacylglycerol kinases (DGKs). This review describes the mechanism of action of eighteen intracellular inhibitory regulatory proteins in T cells within these four classes, and assesses their potential value as clinical targets to enhance the anti-tumor activity of endogenous T cells and CAR-T cells.

Current role of non-coding RNAs in the clinical setting

Non-coding RNAs (ncRNAs) have long been considered as "junk" material of the human genome until functional studies have exposed them as critical regulators of gene expression in both physiological and pathological conditions. Mounting evidences have also shown that ncRNAs may serve as diagnostic markers for several disorders, predictor for drugs response, and targets for new therapeutic approaches. In this mini-review, we discuss the state of the art of non-coding RNAs in drug development and their involvement in conventional treatments response.

The Emerging Epigenetic Role of CD8+T Cells in Autoimmune Diseases: A Systematic Review

Autoimmune diseases are usually complex and multifactorial, characterized by aberrant production of autoreactive immune cells and/or autoantibodies against healthy cells and tissues. However, the pathogenesis of autoimmune diseases has not been clearly elucidated. The activation, differentiation, and development of CD8+ T cells can be affected by numerous inflammatory cytokines, transcription factors, and chemokines. In recent years, epigenetic modifications have been shown to play an important role in the fate of CD8+ T cells. The discovery of these modifications that contribute to the activation or suppression of CD8+ cells has been concurrent with the increasing evidence that CD8+ T cells play a role in autoimmunity. These relationships have been studied in various autoimmune diseases, including multiple sclerosis (MS), systemic sclerosis (SSc), type 1 diabetes (T1D), Grave's disease (GD), systemic lupus erythematosus (SLE), aplastic anemia (AA), and vitiligo. In each of these diseases, genes that play a role in the proliferation or activation of CD8+ T cells have been found to be affected by epigenetic modifications. Various cytokines, transcription factors, and other regulatory molecules have been found to be differentially methylated in CD8+ T cells in autoimmune diseases. These genes are involved in T cell regulation, including interferons, interleukin (IL),tumor necrosis factor (TNF), as well as linker for activation of T cells (LAT), cytotoxic T-lymphocyte–associated antigen 4 (CTLA4), and adapter proteins. MiRNAs also play a role in the pathogenesis of these diseases and several known miRNAs that are involved in these diseases have also been shown to play a role in CD8+ regulation.

Role of miRNAs in immune responses and immunotherapy in cancer

In the past decade, the study of mechanisms of cancer immunity has seen a prominent boom, which paralleled the increased amount of research on the clinical efficacy of immune checkpoint blockade in several lethal types of cancers. This conspicuous effort has led to the development of successful immunotherapy treatment strategies, whose medical impact has been recognized by the awarding of 2018 Nobel Prize in Physiology or Medicine to the two pioneers of check point inhibitor research, Tasuku Honjo and James Allison. Despite these promising achievements, the differences in the clinical response rate in different cancer patients and the high risk of toxicity of immune-based therapies represent crucial challenges. More remarkably, the causes responsible for different outcome (success vs failure) in patients with tumor having same histotype and clinical characteristics remain mostly unknown. MicroRNAs (miRNAs), small regulatory noncoding RNA molecules representing the most studied component of the dark matter of the human genome, are involved in the regulation of many pathways of cancer and immune cells. Therefore, understanding the role of miRNAs in controlling cancer immunity is necessary, as it can contribute to reveal mechanisms that can be modulated to improve the success of immunetherapy in cancer patients. Here, we discuss the latest findings on immune pathways regulated by miRNAs in cancer, miRNA-mediated regulation of immune cells in the tumor microenvironment, and miRNAs as potential target for immunotherapies.

Emodin, a natural anthraquinone, suppresses liver cancer in vitro and in vivo by regulating VEGFR2 and miR-34a

The pharmacokinetic (PK) and potential effects of Emodin on liver cancer were systematically evaluated in this study. Both the intragastric administration (i.g.) and hypodermic injection (i.h.) of Emodin exhibited a strong absorption (absorption rate < 1 h) and elimination capacity (t_1/2 ≈ 2 h). The tissue distribution of Emodin after i.h. was rapid and wide. The stability of Emodin in three species of liver microsomes wasrat >human> beagle dog. These PK data provided the basis for the subsequent animal experiments. In liver cancer patient tissues, the expression of vascular endothelial growth factor (VEGF)-induced signaling pathways, including phosphorylated VEGF receptor 2 (VEGFR₂), AKT, and ERK_1/2,were simultaneously elevated, but miR-34a expression was reduced and negatively correlated with SMAD₂ and SMAD₄. Emodin inhibited the expression of SMAD_2/4 in HepG2 cells by inducing the miR-34a level. Subsequently, BALB/c nude mice received a daily subcutaneous injection of HepG2 cells with or without Emodin treatment (1 mg/kg or 10 mg/kg), and Emodin inhibited tumorigenesis and reduced the mortality rate in a dose-dependent manner. In vivo experiments showed that cell proliferation, migration, and invasion were promoted by VEGF or miR-34a signal treatment but were inhibited when combined with Emodin treatment. All these results demonstrated that Emodin inhibited tumorigenesis in liver cancer by simultaneously inhibiting the VEGFR₂-AKT-ERK_1/2signaling pathway and promoting a miR-34a-mediated signaling pathway.

Differentially circulating exosomal microRNAs expression profiling in oral lichen planus

Oral lichen planus (OLP) is a common chronic inflammatory autoimmune disease with unclear etiology. The aim of the present study was to identify the expression profiles of circulating exosomal miRNAs, which have been shown to be potent stimulators of inflammatory and immune responses, in OLP patients. Plasma exosomes were isolated from the patients and healthy individuals, and RAE scoring system was used to evaluate the severity of OLP. Differentially deregulated exosomal miRNAs associated with inflammatory response and autoimmunity in OLP were identified by miScript^® miRNA PCR Array, and the results were confirmed by RT-PCR. The relationship between exosomal miRNAs and RAE scores was then analyzed, and bioinformatics analysis was used to predict the target genes and pathways of the differentially expressed exosomal miRNAs. Expression profiling showed that circulating exosomal miR-34a-5p and miR-130b-3p were upregulated, while miR-301b-3p was downregulated in OLP patients. Exosomal miR-34a-5p was positively correlated with the severity of OLP. Bioinformatics analysis revealed that the target genes of miR-34a-5p were mainly involved in regulation of gene expression, cell communication, signaling, and metabolic process, and modulated OLP progression through the PI3K/Akt signaling pathway. In conclusion, circulating exosomal miR-34a-5p could be a potential biomarker for evaluating the severity of OLP.

Differential MicroRNA Expression Levels in Cutaneous Acute Graft-Versus-Host Disease

Allogeneic hematopoietic stem cell transplantation is a curative treatment for numerous hematological malignancies. However, acute graft-versus-host disease (aGvHD) is a major complication affecting 40-70% of all transplant patients, whereby the earliest and most frequent presentation is in the skin. MicroRNAs play a role in varied biological process and have been reported as potential biomarkers for aGvHD. More recently, microRNAs have received added attention as circulatory biomarkers that can be detected in biofluids. In this study, we performed global microRNA expression profiling using a discovery cohort of diagnostic cutaneous aGvHD biopsies (n = 5, stages 1-3) and healthy volunteers (n = 4), in order to identify a signature list of microRNAs that could be used as diagnostic biomarkers for cutaneous aGvHD. Candidate microRNAs (n = 8) were then further investigated in a validation cohort of post-HSCT skin biopsies (n = 17), pre-HSCT skin biopsies (n = 6) and normal controls (n = 6) for their association with aGvHD. Expression of let-7c (p = 0.014), miR-503-5p (p = 0.003), miR-365a-3p (p = 0.02), miR-34a-5p (p < 0.001) and miR-34a-3p (p = 0.006) were significantly differentially expressed between groups and significantly associated with survival outcome in post-HSCT patients (miR-503-5p ROC AUC = 0.83 p = 0.021, Log Rank p = 0.003; miR-34a-3p ROC AUC = 0.93, p = 0.003, Log Rank p = 0.004). There was no association with relapse. A statistical interaction between miR-34a-3p and miR-503-5p (p = 0.016) was diagnostic for aGvHD. Expression levels of the miR-34a-5p protein target p53 were assessed in the epidermis of the skin, and an inverse correlation was identified (r² = 0.44, p = 0.039). Expression of the validated candidate microRNAs was also assessed at day 28 post-HSCT in the sera of transplant recipients, in order to investigate their potential as circulatory microRNA biomarkers. Expression of miR-503-5p (p = 0.001), miR-34a-5p (p = 0.005), and miR-34a-3p (p = 0.004) was significantly elevated in the sera of patients who developed aGvHD versus no-aGvHD (n = 30) and miR-503-5p was associated with overall survival (OS) (ROC AUC = 0.80, p = 0.04, Log Rank p = 0.041). In conclusion, this investigation reports that microRNA expression levels in clinical skin biopsies, obtained at the time of cutaneous aGvHD onset, show potential as diagnostic biomarkers for aGvHD and as predictive biomarkers for OS. In addition, the same microRNAs can be detected in the circulation and show predictive association with post-HSCT outcomes.

Dual Suppressive Effect of miR-34a on the FOXM1/eEF2-Kinase Axis Regulates Triple-Negative Breast Cancer Growth and Invasion

Purpose: Recent studies indicated that dysregulation of noncoding RNAs (ncRNA) such as miRNAs is involved in pathogenesis of various human cancers. However, the molecular mechanisms underlying miR-34a are not fully understood in triple-negative breast cancer (TNBC).Experimental Design: We performed in vitro functional assays on TNBC cell lines to investigate the role of miR-34a in FOXM1/eEF2K signaling axis. TNBC tumor xenograft models were used for in vivo therapeutic delivery of miR-34a.Results: In this study, we investigated the role of p53-driven ncRNA miR-34a and found that miR-34a is associated with significantly longer patient survival in TNBC and inversely correlated with levels of proto-oncogenic eEF2K, which was associated with significantly shorter overall patient survival. We showed that miR-34a directly binds to the 3'-untranslated region of eEF2K and FOXM1 mRNAs and suppresses their expression, leading to inhibition of TNBC cell proliferation, motility, and invasion. Notably, restoring miR-34a expression recapitulated the effects of inhibition of eEF2K and FOXM1, the transcription factor for eEF2K and the direct target of p53, in TNBC cell lines, whereas overexpression of eEF2K and FOXM1 rescued the effects and signaling pathways mediated by miR-34a. Moreover, in vivo therapeutic delivery of miR-34a nanoparticles by systemic intravenous administration delayed tumor growth of two different orthotopic TNBC tumor xenograft models by inhibiting eEF2K and FOXM1, intratumoral proliferation and angiogenesis, and inducing apoptosis.Conclusions: Overall, our findings provide new insights into the tumor suppressor role of miR-34a by dual-targeting of FOXM1/eEF2K signaling axis and suggest that miR-34a-based gene therapy may be a potential therapeutic strategy in TNBC. Clin Cancer Res; 24(17); 4225-41. ©2018 AACR.

Augmented frontal cortex diacylglycerol levels in Parkinson's disease and Lewy Body Disease

Background

Research from our laboratory, and that of other investigators, has demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of subjects with Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI). We have extended these observations to investigate the frontal cortex of subjects with Parkinson’s disease (PD) and Lewy Body Disease (LBD), with and without coexisting pathologic features of AD.

Methods/Principal findings

Utilizing a high-resolution mass spectrometry analytical platform, we clearly demonstrate that DAG levels are significantly increased in the frontal cortex of subjects with PD, LBD with intermediate neocortical AD neuropathology, and in LBD with established neocortical AD neuropathology. In the case of the PD cohort, increases in cortical DAG levels were detected in cases with no neocortical pathology but were greater in subjects with neocortical pathology. These data suggest that DAG changes occur early in the disease processes and are amplified as cortical dysfunction becomes more established.

Conclusions

These findings suggest that altered DAG synthesis/metabolism is a common feature of neurodegenerative diseases, characterized by proteinopathy, that ultimately result in cognitive deficits. With regard to the mechanism responsible for these biochemical alterations, selective decrements in cortical levels of phosphatidylcholines in LBD and PD suggest that augmented degradation and/or decreased synthesis of these structural glycerophospholipids may contribute to increases in the pool size of free DAGs. The observed augmentation of DAG levels may be phospholipase-driven since neuroinflammation is a consistent feature of all disease cohorts. If this conclusion can be validated it would support utilizing DAG levels as a biomarker of the early disease process and the investigation of early intervention with anti-inflammatory agents.

Dysregulated miR34a/diacylglycerol kinase ζ interaction enhances T-cell activation in acquired aplastic anemia

Acquired aplastic anemia is an idiopathic paradigm of human bone marrow failure syndrome, which involves active destruction of hematopoietic stem cells and progenitors by cytotoxic T cells in the bone marrow. Aberrant expression of microRNAs in T cells has been shown to lead to development of certain autoimmune diseases. In the present study, we performed a microarray analysis of miRNA expression in bone marrow CD3⁺ T cells from patients with aplastic anemia and healthy controls. Overexpression of miR34a and underexpression of its target gene diacylglycerol kinase (DGK) ζ in bone marrow mononuclear cells were validated in 41 patients and associated with the severity of aplastic anemia. Further, the level of miR34a was higher in naïve T cells from patients than from controls. The role of miR34a and DGKζ in aplastic anemia was investigated in a murine model of immune-mediated bone marrow failure using miR34a^−/− mice. After T-cell receptor stimulation in vitro, lymph node T cells from miR34a^−/− mice demonstrated reduced activation and proliferation accompanied with a less profound down-regulation of DGKζ expression and decreased ERK phosphorylation compared to those from wild-type C57BL6 control mice. Infusion of 5 × 10⁶ miR34a^−/− lymph node T cells into sublethally irradiated CB6F1 recipients led to increased Lin^-Sca1⁺CD117⁺ cells and less vigorous expansion of CD8⁺ T cells than injection of same number of wild-type lymph node cells. Our study demonstrates that the miR34a/DGKζ dysregulation enhances T-cell activation in aplastic anemia and targeting miR34a may represent a novel molecular therapeutic approach for patients with aplastic anemia.

Alternative mechanisms of miR-34a regulation in cancer

MicroRNA miR-34a is recognized as a master regulator of tumor suppression. The strategy of miR-34a replacement has been investigated in clinical trials as the first attempt of miRNA application in cancer treatment. However, emerging outcomes promote the re-evaluation of existing knowledge and urge the need for better understanding the complex biological role of miR-34a. The targets of miR-34a encompass numerous regulators of cancer cell proliferation, survival and resistance to therapy. MiR-34a expression is transcriptionally controlled by p53, a crucial tumor suppressor pathway, often disrupted in cancer. Moreover, miR-34a abundance is fine-tuned by context-dependent feedback loops. The function and effects of exogenously delivered or re-expressed miR-34a on the background of defective p53 therefore remain prominent issues in miR-34a based therapy. In this work, we review p53-independent mechanisms regulating the expression of miR-34a. Aside from molecules directly interacting with MIR34A promoter, processes affecting epigenetic regulation and miRNA maturation are discussed. Multiple mechanisms operate in the context of cancer-associated phenomena, such as aberrant oncogene signaling, EMT or inflammation. Since p53-dependent tumor-suppressive mechanisms are disturbed in a substantial proportion of malignancies, we summarize the effects of miR-34a modulation in cell and animal models in the clinically relevant context of disrupted or insufficient p53 function.

Long non-coding RNAs associated with non-small cell lung cancer

Lung cancer, with 80–85% being non-small cell lung cancer (NSCLC), is the leading cause of cancer-related death in both men and women. Long non-coding RNAs (lncRNAs), always defined as non-protein-coding RNA molecules longer than 200 nucleotides, are now thought as a new frontier in the study of human malignant diseases including NSCLC. As researches continue, increasing number of roles that lncRNAs play in NSCLC has been found, and more and more evidences show lncRNAs have a close relationship with patients’ response to radiochemotherapy or molecular therapy. The aim of this review is to disclose the roles that lncRNAs play in NSCLC and how lncRANs influence the treatment of NSCLC.

Inhibition of microRNA-34a ameliorates murine collagen-induced arthritis

Rheumatoid arthritis (RA) is one of the most frequently occurring autoimmne diseases, with symptoms including synovium hyperplasia, immune disorder, cartilage damage and bone resorption. It has previously been demonstrated that microRNA-34a (miR-34a) may participate in cell apoptosis, immune activation and bone metabolism, therefore the present study investigated the effects of miR-34a on RA. Collagen-induced arthritic (CIA) mice were employed as a murine model of experimental arthritis, and it was demonstrated that the level of miR-34a in the spleens, lymph nodes and synovium was increased in the CIA mice compared with normal DBA/1j mice. Administration of miR-34a antagomir, the chemically modified inhibitor, ameliorated CIA and delayed the onset of symptoms. Arthritis scores decreased and joint swelling was alleviated with the miR-34a antagomir treatment and the expression of inflammatory cytokines was decreased. miR-34a antagomir delivery significantly decreased the percentage of T cells present including T helper (Th) 1, Th2, Th17 and regulatory T cells. Furthermore miR-34a antagomir-treated CIA mice demonstrated decreased inflammatory-induced bone loss. Overall, it was observed that inhibition of miR-34a ameliorated murine arthritis, downregulated T cell percentage and cytokine expression, and suppressed bone loss. The experimental results suggest that inhibition of miR-34a may offer a novel alternative for the treatment of RA.

Radiation-inducible miR-770-5p sensitizes tumors to radiation through direct targeting of PDZ-binding kinase

Radiotherapy represents the most effective non-surgical modality in cancer treatment. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression, and are involved in many biological processes and diseases. To identify miRNAs that influence the radiation response, we performed miRNA array analysis using MCF7 cells at 2, 8, and 24 h post irradiation. We demonstrated that miR-770-5p is a novel radiation-inducible miRNA. When miR-770-5p was overexpressed, relative cell number was reduced due to increased apoptosis in MCF7 and A549 cells. Transcriptomic and bioinformatic analyses revealed that PDZ-binding kinase (PBK) might be a possible target of miR-770-5p for regulation of radiosensitivity. PBK regulation mediated by direct targeting of miR-770-5p was demonstrated using luciferase reporter assays along with wild-type and mutant PBK-3′untranslated region constructs. Radiation sensitivity increased and decreased in miR-770-5p- and anti-miR-770-5p-transfected cells, respectively. Consistent with this result, transfection of short interfering RNA against PBK inhibited cell proliferation, while ectopic expression of PBK restored cell survival from miR-770-5p-induced cell death. In addition, miR-770-5p suppressed tumor growth, and miR-770-5p and PBK levels were inversely correlated in xenograft model mice. Altogether, these data demonstrated that miR-770-5p might be a useful therapeutic target miRNA that sensitizes tumors to radiation via negative regulation of PBK.

Synergy between next generation EGFR tyrosine kinase inhibitors and miR-34a in the inhibition of non-small cell lung cancer

OBJECTIVES

EGFR tyrosine kinase inhibitors (TKIs) are widely used to treat NSCLC, primarily patients with activating mutations, with more limited response in wild-type disease. However, even with EGFR-mutated disease, many patients fail to respond, most who initially respond fail to respond completely, and almost all develop resistance and inevitably progress. New therapeutic options that improve these outcomes could provide substantial clinical benefit. We previously demonstrated strong synergistic effects between erlotinib and the tumor suppressor microRNA miR-34a, sensitizing NSCLC cells with primary resistance (EGFR wild-type) and restoring sensitivity in cells with acquired resistance. Here, we report results of further research combining miR-34a with newer generation EGFR-TKIs in similar experiments.

MATERIALS AND METHODS

Human NSCLC cell lines with varying degrees of primary and acquired resistance to erlotinib were assessed for sensitivity to a broad set of combined doses of miR-34a mimic and afatinib, rociletinib or osimertinib. Multiple analytical approaches were used to characterize effects on cancer cell proliferation as additive, antagonistic or synergistic.

RESULTS

Mimics of miR-34a synergized with afatinib, rociletinib or osimertinib in all EFGR-mutant cells tested. Best and consistently strong synergy was observed in cell models with acquired resistance. Synergy was also evident in most EGFR wild-type cells with miR-34a combined with rociletinib and osimertinib, but not with afatinib. The effects were observed across a broad range of dose levels and drug ratios, with maximal synergy at doses yielding high levels of inhibition beyond those possible to be induced by the single agents alone.

CONCLUSION

Combined miR-34a and EGFR-TKIs synergistically sensitize both EGFR wild-type and mutant NSCLC cells, supporting clinical investigation of these combinations as a strategy to overcome both primary and acquired resistance to EGFR-TKIs in NSCLC, possibly with an improved therapeutic index.

Phase I study of MRX34, a liposomal miR-34a mimic, administered twice weekly in patients with advanced solid tumors

Purpose Naturally occurring tumor suppressor microRNA-34a (miR-34a) downregulates the expression of >30 oncogenes across multiple oncogenic pathways, as well as genes involved in tumor immune evasion, but is lost or under-expressed in many malignancies. This first-in-human, phase I study assessed the maximum tolerated dose (MTD), safety, pharmacokinetics, and clinical activity of MRX34, a liposomal miR-34a mimic, in patients with advanced solid tumors. Patients and Methods Adult patients with solid tumors refractory to standard treatment were enrolled in a standard 3 + 3 dose escalation trial. MRX34 was given intravenously twice weekly (BIW) for three weeks in 4-week cycles. Results Forty-seven patients with various solid tumors, including hepatocellular carcinoma (HCC; n = 14), were enrolled. Median age was 60 years, median prior therapies was 4 (range, 1-12), and most were Caucasian (68%) and male (57%). Most common adverse events (AEs) included fever (all grade %/G3%: 64/2), fatigue (57/13), back pain (57/11), nausea (49/2), diarrhea (40/11), anorexia (36/4), and vomiting (34/4). Laboratory abnormalities included lymphopenia (G3%/G4%: 23/9), neutropenia (13/11), thrombocytopenia (17/0), increased AST (19/4), hyperglycemia (13/2), and hyponatremia (19/2). Dexamethasone premedication was required to manage infusion-related AEs. The MTD for non-HCC patients was 110 mg/m², with two patients experiencing dose-limiting toxicities of G3 hypoxia and enteritis at 124 mg/m². The half-life was >24 h, and C_max and AUC increased with increasing dose. One patient with HCC achieved a prolonged confirmed PR lasting 48 weeks, and four patients experienced SD lasting ≥4 cycles. Conclusion MRX34 treatment with dexamethasone premedication was associated with acceptable safety and showed evidence of antitumor activity in a subset of patients with refractory advanced solid tumors. The MTD for the BIW schedule was 110 mg/m² for non-HCC and 93 mg/m2 for HCC patients. Additional dose schedules of MRX34 have been explored to improve tolerability.

Diacylglycerol Kinases in T Cell Tolerance and Effector Function

Diacylglycerol kinases (DGKs) are a family of enzymes that regulate the relative levels of diacylglycerol (DAG) and phosphatidic acid (PA) in cells by phosphorylating DAG to produce PA. Both DAG and PA are important second messengers cascading T cell receptor (TCR) signal by recruiting multiple effector molecules, such as RasGRP1, PKCθ, and mTOR. Studies have revealed important physiological functions of DGKs in the regulation of receptor signaling and the development and activation of immune cells. In this review, we will focus on recent progresses in our understanding of two DGK isoforms, α and ζ, in CD8 T effector and memory cell differentiation, regulatory T cell development and function, and invariant NKT cell development and effector lineage differentiation.

Diacylglycerol Kinases in the Coordination of Synaptic Plasticity

Synaptic plasticity is activity-dependent modification of the efficacy of synaptic transmission. Although, detailed mechanisms underlying synaptic plasticity are diverse and vary at different types of synapses, diacylglycerol (DAG)-associated signaling has been considered as an important regulator of many forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Recent evidences indicate that DAG kinases (DGKs), which phosphorylate DAG to phosphatidic acid to terminate DAG signaling, are important regulators of LTP and LTD, as supported by the results from mice lacking specific DGK isoforms. This review will summarize these studies and discuss how specific DGK isoforms distinctly regulate different forms of synaptic plasticity at pre- and postsynaptic sites. In addition, we propose a general role of DGKs as coordinators of synaptic plasticity that make local synaptic environments more permissive for synaptic plasticity by regulating DAG concentration and interacting with other synaptic proteins.

Targeted Lipidomics of Fontal Cortex and Plasma Diacylglycerols (DAG) in Mild Cognitive Impairment and Alzheimer's Disease: Validation of DAG Accumulation Early in the Pathophysiology of Alzheimer's Disease

Previous studies have demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of Alzheimer's disease (AD) patients. We extended these findings from non-targeted lipidomics studies to design a lipidomics platform to interrogate DAGs and monoacylglycerols (MAG) in the frontal cortex and plasma of MCI subjects. Control subjects included both aged normal controls and controls with normal cognition, but AD pathology at autopsy, individuals termed non-demented AD neuropathology. DAGs with saturated, unsaturated, and polyunsaturated fatty acid substituents were found to be elevated in MCI frontal cortex and plasma. Tandem mass spectrometry of the DAGs did not reveal any differences in the distributions of the fatty acid substitutions between MCI and control subjects. While triacylglycerols were not altered in MCI subjects there were increases in MAG levels both in the frontal cortex and plasma. In toto, increased levels of DAGs and MAGs appear to occur early in AD pathophysiology and require both further validation in a larger patient cohort and elucidation of the lipidomics alteration(s) that lead to the accumulation of DAGs in MCI subjects.

PDL1 Regulation by p53 via miR-34

BACKGROUND

Although clinical studies have shown promise for targeting PD1/PDL1 signaling in non-small cell lung cancer (NSCLC), the regulation of PDL1 expression is poorly understood. Here, we show that PDL1 is regulated by p53 via miR-34.

METHODS

p53 wild-type and p53-deficient cell lines (p53(-/-) and p53(+/+) HCT116, p53-inducible H1299, and p53-knockdown H460) were used to determine if p53 regulates PDL1 via miR-34. PDL1 and miR-34a expression were analyzed in samples from patients with NSCLC and mutated p53 vs wild-type p53 tumors from The Cancer Genome Atlas for Lung Adenocarcinoma (TCGA LUAD). We confirmed that PDL1 is a direct target of miR-34 with western blotting and luciferase assays and used a p53(R172HΔ)g/+K-ras(LA1/+) syngeneic mouse model (n = 12) to deliver miR-34a-loaded liposomes (MRX34) plus radiotherapy (XRT) and assessed PDL1 expression and tumor-infiltrating lymphocytes (TILs). A two-sided t test was applied to compare the mean between different treatments.

RESULTS

We found that p53 regulates PDL1 via miR-34, which directly binds to the PDL1 3' untranslated region in models of NSCLC (fold-change luciferase activity to control group, mean for miR-34a = 0.50, SD = 0.2, P < .001; mean for miR-34b = 0.52, SD = 0.2, P = .006; and mean for miR-34c = 0.59, SD = 0.14, and P = .006). Therapeutic delivery of MRX34, currently the subject of a phase I clinical trial, promoted TILs (mean of CD8 expression percentage of control group = 22.5%, SD = 1.9%; mean of CD8 expression percentage of MRX34 = 30.1%, SD = 3.7%, P = .016, n = 4) and reduced CD8(+)PD1(+) cells in vivo (mean of CD8/PD1 expression percentage of control group = 40.2%, SD = 6.2%; mean of CD8/PD1 expression percentage of MRX34 = 20.3%, SD = 5.1%, P = .001, n = 4). Further, MRX34 plus XRT increased CD8(+) cell numbers more than either therapy alone (mean of CD8 expression percentage of MRX34 plus XRT to control group = 44.2%, SD = 8.7%, P = .004, n = 4). Finally, miR-34a delivery reduced the numbers of radiation-induced macrophages (mean of F4-80 expression percentage of control group = 52.4%, SD = 1.7%; mean of F4-80 expression percentage of MRX34 = 40.1%, SD = 3.5%, P = .008, n = 4) and T-regulatory cells.

CONCLUSIONS

We identified a novel mechanism by which tumor immune evasion is regulated by p53/miR-34/PDL1 axis. Our results suggest that delivery of miRNAs with standard therapies, such as XRT, may represent a novel therapeutic approach for lung cancer.