Expression of orphan nuclear receptor NR4A2 in gastric cancer cells confers chemoresistance and predicts an unfavorable postoperative survival of gastric cancer patients with chemotherapy

A pan-cancer analysis unveiling the function of NR4A family genes in tumor immune microenvironment, prognosis, and drug response

BACKGROUND

NR4A family genes play crucial roles in cancers. However, the role of NR4A family genes in cancers remains paradoxical as they promote or suppress tumorigenesis.

OBJECTIVE

We aimed to conduct comprehensive analyses of the association between the expression of NR4A family genes and tumor microenvironment (TME) based on bioinformatics methods.

METHODS

We collected RNA-seq data from 33 cancer types and 20 normal tissue sites from the TCGA and GTEx databases. Expression patterns of NR4A family genes and their associations with DNA methylation, miRNA, overall survival, drug responses, and tumor microenvironment were investigated.

RESULTS

Significant downregulation of all NR4A family genes was observed in 15 cancer types. DNA promoter methylation and expression of NR4A family genes were negatively correlated in five cancers. The expression of 10 miRNAs targeting NR4A family genes was negatively correlated with the expression of NR4A family genes. High expression of all NR4A family genes was associated with poor prognosis in stomach adenocarcinoma and increased expressions of NR4A2 and NR4A3 were associated with poor prognosis in adrenocortical carcinoma. In addition, we found an elevated expression of NR4A2, which enhances the response to various chemotherapeutic drugs, whereas NR4A3 decreases drug sensitivity. Interestingly, in breast cancer, NR4A3 was significantly associated with C2 (IFN-γ dominant), C3 (inflammatory), and C6 (TGF-β dominant) immune subtypes and infiltrated immune cell types, implying both oncogenic and tumor-suppressive functions of NR4A3 in breast cancer.

CONCLUSION

The NR4A family genes have the potential to serve as a diagnostic, prognostic, and immunological marker of human cancers.

The role of microbiota in gastric cancer: A comprehensive review

BACKGROUND

Gastric cancer (GC) continues to pose a significant global threat in terms of cancer-related fatalities. Despite notable advancements in medical research and therapies, further investigation is warranted to elucidate its underlying etiology and risk factors. Recent times have witnessed an escalated emphasis on comprehending the role of the microbiota in cancer development.

METHODS

This review briefly delves into recent developments in microbiome-related research pertaining to gastric cancer.

RESULTS

According to studies, the microbiota can influence GC growth by inciting inflammation, disrupting immunological processes, and generating harmful microbial metabolites. Furthermore, there is ongoing research into how the microbiome can impact a patient's response to chemotherapy and immunotherapy.

CONCLUSION

The utilization of the microbiome for detecting, preventing, and managing stomach cancer remains an active area of exploration.

Novel players in the development of chemoresistance in ovarian cancer: ovarian cancer stem cells, non-coding RNA and nuclear receptors

Ovarian cancer (OC) ranks as the fifth leading factor for female mortality globally, with a substantial burden of new cases and mortality recorded annually. Survival rates vary significantly based on the stage of diagnosis, with advanced stages posing significant challenges to treatment. OC is primarily categorized as epithelial, constituting approximately 90% of cases, and correct staging is essential for tailored treatment. The debulking followed by chemotherapy is the prevailing treatment, involving platinum-based drugs in combination with taxanes. However, the efficacy of chemotherapy is hindered by the development of chemoresistance, both acquired during treatment (acquired chemoresistance) and intrinsic to the patient (intrinsic chemoresistance). The emergence of chemoresistance leads to increased mortality rates, with many advanced patients experiencing disease relapse shortly after initial treatment. This review delves into the multifactorial nature of chemoresistance in OC, addressing mechanisms involving transport systems, apoptosis, DNA repair, and ovarian cancer stem cells (OCSCs). While previous research has identified genes associated with these mechanisms, the regulatory roles of non-coding RNA (ncRNA) and nuclear receptors in modulating gene expression to confer chemoresistance have remained poorly understood and underexplored. This comprehensive review aims to shed light on the genes linked to different chemoresistance mechanisms in OC and their intricate regulation by ncRNA and nuclear receptors. Specifically, we examine how these molecular players influence the chemoresistance mechanism. By exploring the interplay between these factors and gene expression regulation, this review seeks to provide a comprehensive mechanism driving chemoresistance in OC.

Smoke and Spike: Benzo[a]pyrene Enhances SARS-CoV-2 Infection by Boosting NR4A2-Induced ACE2 and TMPRSS2 Expression

Cigarette smoke aggravates severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the underlying mechanisms remain unclear. Here, they show that benzo[a]pyrene in cigarette smoke extract facilitates SARS-CoV-2 infection via upregulating angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Benzo[a]pyrene trans-activates the promoters of ACE2 and TMPRSS2 by upregulating nuclear receptor subfamily 4 A number 2 (NR4A2) and promoting its binding of NR4A2 to their promoters, which is independent of functional genetic polymorphisms in ACE2 and TMPRSS2. Benzo[a]pyrene increases the susceptibility of lung epithelial cells to SARS-CoV-2 pseudoviruses and facilitates the infection of authentic Omicron BA.5 in primary human alveolar type II cells, lung organoids, and lung and testis of hamsters. Increased expression of Nr4a2, Ace2, and Tmprss2, as well as decreased methylation of CpG islands at the Nr4a2 promoter are observed in aged mice compared to their younger counterparts. NR4A2 knockdown or interferon-λ2/λ3 stimulation downregulates the expression of NR4A2, ACE2, and TMPRSS2, thereby inhibiting the infection. In conclusion, benzo[a]pyrene enhances SARS-CoV-2 infection by boosting NR4A2-induced ACE2 and TMPRSS2 expression. This study elucidates the mechanisms underlying the detrimental effects of cigarette smoking on SARS-CoV-2 infection and provides prophylactic options for coronavirus disease 2019, particularly for the elderly population.

Mechanisms of NURR1 Regulation: Consequences for Its Biological Activity and Involvement in Pathology

NURR1 (Nuclear receptor-related 1 protein or NR4A2) is a nuclear protein receptor transcription factor with an essential role in the development, regulation, and maintenance of dopaminergic neurons and mediates the response to stressful stimuli during the perinatal period in mammalian brain development. The dysregulation of NURR1 activity may play a role in various diseases, including the onset and progression of neurodegenerative diseases, and several other pathologies. NURR1 is regulated by multiple mechanisms, among which phosphorylation by kinases or SUMOylation are the best characterized. Both post-translational modifications can regulate the activity of NURR1, affecting its stability and transcriptional activity. Other non-post-translational regulatory mechanisms include changes in its subcellular distribution or interaction with other protein partners by heterodimerization, also affecting its transcription activity. Here, we summarize the currently known regulatory mechanisms of NURR1 and provide a brief overview of its participation in pathological alterations.

Inflammation and Gastric Cancer

Gastric cancer remains a major killer globally, although its incidence has declined over the past century. It is the fifth most common cancer and the third most common reason for cancer-related deaths worldwide. Gastric cancer is the outcome of a complex interaction between environmental, host genetic, and microbial factors. There is significant evidence supporting the association between chronic inflammation and the onset of cancer. This association is particularly robust for gastrointestinal cancers in which microbial pathogens are responsible for the chronic inflammation that can be a triggering factor for the onset of those cancers. Helicobacter pylori is the most prominent example since it is the most widespread infection, affecting nearly half of the world’s population. It is well-known to be responsible for inducing chronic gastric inflammation progressing to atrophy, metaplasia, dysplasia, and eventually, gastric cancer. This review provides an overview of the association of the factors playing a role in chronic inflammation; the bacterial characteristics which are responsible for the colonization, persistence in the stomach, and triggering of inflammation; the microbiome involved in the chronic inflammation process; and the host factors that have a role in determining whether gastritis progresses to gastric cancer. Understanding these interconnections may improve our ability to prevent gastric cancer development and enhance our understanding of existing cases.

Nuclear Receptor 4A2 (NR4A2/NURR1) Regulates Autophagy and Chemoresistance in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with poor prognosis and chemotherapy with gemcitabine has limited effects and is associated with development of drug resistance. Treatment of Panc1 and MiaPaca2 pancreatic cancer cells with gemcitabine induced expression of the orphan nuclear receptor 4A2 (NURR1) and analysis of the cancer genome atlas indicated the NURR1 is overexpressed in pancreatic tumors and is a negative prognostic factor for patient survival. Results of NURR1 knockdown or treatment with the NURR1 antagonist 1,1-bis(3΄-indolyl)-1-(p-chlorophenyl)methane (C-DIM 12) demonstrated that NURR1 was pro-oncogenic in pancreatic cancer cells and regulated cancer cell and tumor growth and survival. NURR1 is induced by gemcitabine and serves as a key drug-resistance factor and is also required for gemcitabine-induced cytoprotective autophagy. NURR1 regulated genes were determined by RNA sequencing of mRNAs expressed in MiaPaCa2 cells expressing NURR1 and in CRISPR/Cas9 gene edited cells for NURR1 knockdown and KEGG enrichment analysis of the differentially expressed genes showed that autophagy was the major pathway regulated by NURR1. Moreover, NURR1 regulated expression of two major autophagic genes ATG7 and ATG12 which are also overexpressed in pancreatic tumors and like NURR1 are negative prognostic factors for patient survival. Thus, gemcitabine-induced cytoprotective autophagy is due to the NURR1 - ATG7/ATG12 axis and this can be targeted and disrupted by NURR1 antagonist C-DIM12 demonstrating the potential clinical applications for combination therapies with gemcitabine and NURR1 antagonists.

Aberrant mTOR/autophagy/Nurr1 signaling is critical for TSC-associated tumor development

Tuberous sclerosis complex (TSC), an inherited neurocutaneous disease, is caused by mutations in either the TSC1 or TSC2 gene. This genetic disorder is characterized by the growth of benign tumors in the brain, kidneys, and other organs. As a member of the orphan nuclear receptor family, nuclear receptor related 1 (Nurr1) plays a vital role in some neuropathological diseases and several types of benign or malignant tumors. Here, we explored the potential regulatory role of TSC1/2 signaling in Nurr1 and the effect of Nurr1 in TSC-related tumors. We found that Nurr1 expression was drastically decreased by the disruption of the TSC1/2 complex in Tsc2-null cells, genetically modified mouse models of TSC, cortical tubers of TSC patients, and kidney tumor tissue obtained from a TSC patient. Deficient TSC1/2 complex downregulated Nurr1 expression in an mTOR-dependent manner. Moreover, hyperactivation of mTOR reduced Nurr1 expression via suppression of autophagy. In addition, Nurr1 overexpression inhibited cell proliferation and suppressed cell cycle progression. Therefore, TSC/mTOR/autophagy/Nurr1 signaling is partially responsible for the tumorigenesis of TSC. Taken together, Nurr1 may be a novel therapeutic target for TSC-associated tumors, and Nurr1 agonists or reagents that induce Nurr1 expression may be used for the treatment of TSC.

Hepatic stellate cells promote intrahepatic cholangiocarcinoma progression via NR4A2/osteopontin/Wnt signaling axis

Intrahepatic cholangiocarcinoma (ICC) is a highly fatal malignancy characterized by a vast amount of intra-tumoral fibroblasts. These fibroblasts are potentially implicated in maintaining the high aggressiveness of ICC, whereas its pro-cancer mechanisms remain scarcely reported. Here, by establishing co-culture models of ICC cells and hepatic stellate cells (HSCs), we identified that HSCs triggered the expression of nuclear receptor family 4 subgroup A member 2 (NR4A2), a transcription factor previously reported as a molecular switch between inflammation and cancer, in ICC cells. Functionally, NR4A2 promotes tumor proliferation, metastatic potentiality and represents an independent prognostic indicator for overall survival in ICC patients. Mechanistically, NR4A2 upregulates osteopontin (OPN) expression through transcriptional activation and thereby augments the activity of Wnt/β-catenin signaling. Intriguingly, in the context of co-culture, vascular endothelial growth factor (VEGF), a previously proved NR4A2 stimulus, not only enhances NR4A2 expression, but also can be blunted by the interference of the NR4A2-OPN axis. Altogether, this study suggests the NR4A2/OPN/Wnt signaling axis to be a pivotal executor of HSC-instigated cancer-promoting roles in ICC, and the NR4A2/OPN/VEGF positive feedback loop may help to reinforce the effect.

Circular RNAs as important players in human gastric cancer

As one of the most prevalent gastrointestinal diseases, gastric cancer (GC) is the second leading cause of cancer-related deaths worldwide. Since GC has no clinical manifestations in the early stage of the disease, most patients are detected in the later phases of disease and have an unfortunately lower chance of recovery. Circular RNAs (circRNAs), a novel category of non-coding RNAs (ncRNAs), are mainly engaged in the regulation of gene expression at the transcriptional and post-transcriptional levels. Numerous evidences have revealed that circRNAs play key roles in GC as they are involved in cell proliferation, growth, and apoptosis via modulating the expression of some target genes, miRNAs, and proteins. Many studies have addressed the impact of circRNA dysregulation on GC initiation, progression, and invasion via binding to miRNAs or RNA binding proteins. Moreover, changes in circRNA expression are associated with pathological and clinical features of GC highlighting their potentials as diagnostic or prognostic biomarkers in GC. In the current study, the recent findings on the significance of circRNAs in the development and progression of GC are reviewed. We focus on the implications of circRNAs as potential diagnostic or prognostic biomarkers in this malignancy.

The Paradoxical Roles of Orphan Nuclear Receptor 4A (NR4A) in Cancer

The three-orphan nuclear receptor 4A genes are induced by diverse stressors and stimuli, and there is increasing evidence that NR4A1 (Nur77), NR4A2 (Nurr1), and NR4A3 (Nor1) play an important role in maintaining cellular homeostasis and in pathophysiology. In blood-derived tumors (leukemias and lymphomas), NR4A expression is low and NR4A1^-/-/NR4A3^-/- double knockout mice rapidly develop acute myelocytic leukemia, suggesting that these receptors exhibit tumor suppressor activity. Treatment of leukemia and most lymphoma cells with drugs that induce expression of NR4A1and NR4A3 enhances apoptosis, and this represents a potential clinical application for treating this disease. In contrast, most solid tumor-derived cell lines express high levels of NR4A1 and NR4A2, and both receptors exhibit pro-oncogenic activities in solid tumors, whereas NR4A3 exhibits tumor-specific activities. Initial studies with retinoids and apoptosis-inducing agents demonstrated that their cytotoxic activity is NR4A1 dependent and involved drug-induced nuclear export of NR4A1 and formation of a mitochondrial proapoptotic NR4A1-bcl-2 complex. Drug-induced nuclear export of NR4A1 has been reported for many agents/biologics and involves interactions with multiple mitochondrial and extramitochondrial factors to induce apoptosis. Synthetic ligands for NR4A1, NR4A2, and NR4A3 have been identified, and among these compounds, bis-indole derived (CDIM) NR4A1 ligands primarily act on nuclear NR4A1 to inhibit NR4A1-regulated pro-oncogenic pathways/genes and similar results have been observed for CDIMs that bind NR4A2. Based on results of laboratory animal studies development of NR4A inducers (blood-derived cancers) and NR4A1/NR4A2 antagonists (solid tumors) may be promising for cancer therapy and also for enhancing immune surveillance.

Role of Nurr1 in Carcinogenesis and Tumor Immunology: A State of the Art Review

Simple Summary

Nuclear receptor related-1 protein (Nurr1) emerges as a therapeutic target in multiple malignancies and immunotherapies. Previous studies have highlighted its association with clinicopathological parameters, tumorigenesis and therapeutic resistance in cancers. In addition, recent studies unraveled its contribution to the suppression of antitumor immunity, suggesting that inhibition of Nurr1 is a potential method to repress cancer aggressiveness and disrupt tumor immune tolerance. In line with this evidence, the present review provides the roles of Nurr1 in tumor progression and the associated underlying molecular mechanisms. Moreover, the significance of Nurr1 in promoting immune tolerance and potential strategies for Nurr1 inhibition are highlighted.

Abstract

Nuclear receptor related-1 protein (Nurr1), coded by an early response gene, is involved in multiple cellular and physiological functions, including proliferation, survival, and self-renewal. Dysregulation of Nurr1 has been frequently observed in many cancers and is attributed to multiple transcriptional and post-transcriptional mechanisms. Besides, Nurr1 exhibits extensive crosstalk with many oncogenic and tumor suppressor molecules, which contribute to its potential pro-malignant behaviors. Furthermore, Nurr1 is a key player in attenuating antitumor immune responses. It not only potentiates immunosuppressive functions of regulatory T cells but also dampens the activity of cytotoxic T cells. The selective accessibility of chromatin by Nurr1 in T cells is closely associated with cell exhaustion and poor efficacy of cancer immunotherapy. In this review, we summarize the reported findings of Nurr1 in different malignancies, the mechanisms that regulate Nurr1 expression, and the downstream signaling pathways that Nurr1 employs to promote a wide range of malignant phenotypes. We also give an overview of the association between Nurr1 and antitumor immunity and discuss the inhibition of Nurr1 as a potential immunotherapeutic strategy.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

Orphan nuclear receptor Nurr1 promotes Helicobacter pylori-associated gastric carcinogenesis by directly enhancing CDK4 expression

BACKGROUND

Abnormal expression of the orphan nuclear receptor Nurr1 is a critical factor in the etiology of multiple cancers. However, its potential role in gastric cancer (GC) remains elusive. In this study, we have demonstrated that the expression of Nurr1 was elevated and had an oncogenic function in GC.

METHODS

Nurr1 expression was analyzed in clinical specimens and the GEO database. Functions of Nurr1 in GC cells were analyzed using Nurr1 knockdown and overexpression. Various cell and molecular biological methods were used to explore the potential mechanisms of Nurr1 upregulation and its role in promoting GC.

FINDINGS

Overexpression of Nurr1 was directly related to the poor prognosis of GC patients. What's more, Nurr1 was induced by Helicobacter pylori (H. pylori) via the PI3K/AKT-Sp1 pathway. Sp1 enhanced Nurr1 expression by binding to its promoter to activate the transcription. Upregulated Nurr1 then directly targeted CDK4 by binding to its promoter region to increase its expression, thereby facilitated GC cells proliferation both in vitro and in vivo.

INTERPRETATION

We identified Nurr1 as a driving oncogenic factor in GC. In addition, Nurr1 could be used as a potential therapeutic target for the diagnosis and treatment of H. pylori-associated GC.

FUNDING

This work was supported by the National Natural Science Foundation of China (Nos 81801983, 81871620, 81971901, 81772151 and 81571960), and the Department of Science and Technology of Shandong Province (2018CXGC1208).

Functional and transcriptomic characterization of cisplatin-resistant AGS and MKN-28 gastric cancer cell lines

Gastric cancer (GC) is a significant cancer-related cause of death worldwide. The most used chemotherapeutic regimen in GC is based on platinum drugs such as cisplatin (CDDP). However, CDDP resistance reduces advanced GC survival. In vitro drug-resistant cell model would help in the understanding of molecular mechanisms underlying this drug-resistance phenomenon. The aim of this study was to characterize new models of CDDP-resistant GC cell lines (AGS R-CDDP and MKN-28 R-CDDP) obtained through a stepwise increasing drug doses method, in order to understand the molecular mechanisms underlying chemoresistance as well as identify new therapeutic targets for the treatment of GC. Cell viability assays, cell death assays and the expression of resistance molecular markers confirmed that AGS R-CDDP and MKN-28 R-CDDP are reliable CDDP-resistant models. RNA-seq and bioinformatics analyses identified a total of 189 DEGs, including 178 up-regulated genes and 11 down-regulated genes, associated mainly to molecular functions involved in CDDP-resistance. DEGs were enriched in 23 metabolic pathways, among which the most enriched was the inflammation mediated by chemokine and cytokine signaling pathway. Finally, the higher mRNA expression of SERPINA1, BTC and CCL5, three up-regulated DEGs associated to CDDP resistance found by RNA-seq analysis was confirmed. In summary, this study showed that AGS R-CDDP and MKN-28 R-CDDP are reliable models of CDDP resistance because resemble many of resistant phenotype in GC, being also useful to assess potential therapeutic targets for the treatment of gastric cancers resistant to CDDP. In addition, we identified several DEGs associated with molecular functions such as binding, catalytic activity, transcription regulator activity and transporter activity, as well as signaling pathways associated with inflammation process, which could be involved in the development of CDDP resistance in GC. Further studies are necessary to clarify the role of inflammatory processes in GC resistant to CDDP and these models could be useful for these purposes.

Nuclear receptor 4A2 (NR4A2) is a druggable target for glioblastomas

INTRODUCTION

The orphan nuclear receptor 4A2 (NR4A2) has been extensively characterized in subcellular regions of the brain and is necessary for the function of dopaminergic neurons. The NR4A2 ligand, 1,1-bis (3¹-indoly1)-1-(p-chlorophenyl)methane (DIM-C-pPhCl) inhibits markers of neuroinflammation and degeneration in mouse models and in this study we investigated expression and function of NR4A2 in glioblastoma (GBM).

METHODS

Established and patient-derived cell lines were used as models and the expression and functions of NR4A2 were determined by western blots and NR4A2 gene silencing by antisense oligonucleotides respectively. Effects of NR4A2 knockdown and DIM-C-pPhCl on cell growth, induction of apoptosis (Annexin V Staining) and migration/invasion (Boyden chamber and spheroid invasion assay) and transactivation of NR4A2-regulated reporter genes were determined. Tumor growth was investigated in athymic nude mice bearing U87-MG cells as xenografts.

RESULTS

NR4A2 knockdown and DIM-C-pPhCl inhibited GBM cell and tumor growth, induced apoptosis and inhibited migration and invasion of GBM cells. DIM-C-pPhCl and related analogs also inhibited NR4A2-regulated transactivation (luciferase activity) confirming that DIM-C-pPhCl acts as an NR4A2 antagonist and blocks NR4A2-dependent pro-oncogenic responses in GBM.

CONCLUSION

We demonstrate for the first time that NR4A2 is pro-oncogenic in GBM and thus a potential druggable target for patients with tumors expressing this receptor. Moreover, our bis-indole-derived NR4A2 antagonists represent a novel class of anti-cancer agents with potential future clinical applications for treating GBM.

A genomewide transcriptomic approach identifies a novel gene expression signature for the detection of lymph node metastasis in patients with early stage gastric cancer

BACKGROUND

Although identification of lymph node (LN) metastasis is a well-recognized strategy for improving outcomes in patients with gastric cancer (GC), currently there is lack of availability of adequate molecular biomarkers that can identify such metastasis. Herein we have developed a robust gene-expression signature for detecting LN metastasis in early stage GC by using a transcriptome-wide biomarker discovery and subsequent validation in multiple clinical cohorts.

METHODS

A total of 532 patients with pathological T1 and T2 GC from 4 different cohorts were analyzed. Two independent datasets (n = 96, and n = 188) were used to establish a gene signature for the identification of LN metastasis in GC patients. The diagnostic performance of our gene-expression signature was subsequently assessed in two independent clinical cohorts using qRT-PCR assays (n = 101, and n = 147), and subsequently compared against conventional tumor markers and image-based diagnostics.

FINDINGS

We established a 15-gene signature by analyzing multiple high throughput datasets, which robustly distinguished LN status in both training (AUC = 0.765, 95% CI 0.667-0.863) and validation cohorts (AUC = 0.742, 95% CI 0.630-0.852). Notably, the 15-gene signature was significantly superior compared to the conventional tumor markers, CEA (P = .04) and CA19-9 (P = .005), as well as computed tomography-based imaging (P = .04).

INTERPRETATION

We have established and validated a 15-gene signature for detecting LN metastasis in GC patients, which offers a robust diagnostic tool for potentially improving treatment outcomes in gastric cancer patients. FUND: NIH: CA72851, CA181572, CA14792, CA202797, CA187956; CPRIT: RP140784: Baylor Sammons Cancer Center polot grants (AG), VPRT: 9610337, CityU 21101115, 11102317, 11103718; JCYJ20170307091256048 (XW).

CircRNA_001569 promotes cell proliferation through absorbing miR-145 in gastric cancer

Gastric cancer severely threatens human life, while its pathogenesis is still unclear. The present study was to explore the potential pathogenic mechanism underlying gastric cancer. Real-time PCR was performed to detect the expression of circRNA_001569 and miR-145; western blot was performed to detect the expression of NR4A2. Cell cycle and apoptosis was determined using flow cytometry, and cell viability was determined using Cell counting kit-8 (CCK-8) assay. Luciferase reporter assay was carried out to validate the relationship between miR-145 and NR4A2. Both circRNA_001569 and NR4A2 were overexpressed in tissues and cells of gastric cancer, while miR-145 was down-regulated. Overexpressed circRNA_001569 significantly increased cell viability, and decreased cell apoptosis, while down-regulated circRNA_001569 dramatically decreased cell viability and promoted cell apoptosis. CircRNA_001569 regulated the expression of miR-145, the effect of pcDNA-circRNA_001569 was abolished by miR-145 mimic and the effect of si-circRNA_001569 was abolished by miR-145 inhibitor. MiR-145 targets NR4A2 to regulate its expression. Overexpressed miR-145 suppressed cell viability and promoted cell apoptosis. Taken together, the present study indicated that overexpressed circRNA_001569 promoted cell viability of gastric cancer through suppressing the expression of miR-145, which was mediated by NR4A2. The research will provide great theoretical basis for further clinical diagnosis and therapy.

Drug screening to target nuclear orphan receptor NR4A2 for cancer therapeutics

Background

Our previous study suggested NR4A2, a subfamily member of orphan nuclear receptors, is essential for survival of human cancer cells such as mucoepidermoid carcinoma (MEC).

Methods

We conducted high throughput drug screening for NR4A2 inhibitors as a novel therapeutic modality. Positive screening was performed using a luciferase reporter vector containing NR4A2 binding sequence, and a CRE-reporter control vector was used to eliminate false positives. In vitro assays for positive hits were conducted.

Results

A total of 23 Food and Drug Administration (FDA) and 43 Life Science Library compounds were identified, including several epidermal growth factor inhibitors and Src inhibitors. Subsequent in vitro assays confirmed that identified compounds were preferentially active in NR4A2+ cancer cells. Several candidate compounds appeared to suppress NR4A2 via inhibition of p-ERK, whereas a novel compound KU0171309 may act as a more direct inhibitor.

Conclusions

Further research should focus on homologue selectivity, in vivo activity, and definitively deciphering the mechanism of action of KU0171309.

NR1H3 Expression is a Prognostic Factor of Overall Survival for Patients with Muscle-Invasive Bladder Cancer

Background: Nuclear receptors (NRs) are a class of transcription factors that regulate many cellular functions through manipulation of gene expression and also play important roles in tumorigenesis, proliferation, progression and prognosis in various kinds of cancers according to recent studies. This work aimed to determine the predictive ability of NRs in muscle-invasive bladder cancer (MIBC).

Patients and methods: A total of 308 MIBC patients with complete clinicopathological and RNASeq data from The Cancer Genome Atlas (TCGA) cohort were collected for filtration. Genes showed clear correlations with overall survival (OS) and recurrence free survival (RFS) were further validated in 123 MIBC patients recruited consecutively from 2008 to 2012 in Fudan University Shanghai Cancer Center (FUSCC) cohort. Cox proportional hazards regression model and Kaplan-Meier plot were used to assess the relative factors.

Results: In TCGA cohort, we found that high NR1H3 (HR=0.779, 95% CI: 0.634 - 0.957), NR2C1 (HR=0.673, 95% CI: 0.458 - 0.989) and NR2F6 (HR=0.750, 95% CI: 0.574 - 0.980) expressions were independent factors of favorable OS, while only low NR1H3 (log-rank test, P=0.0076) and NR2F6 (log-rank test, P=0.0395) expressions had the ability to predict poor prognosis for RFS. Further, in FUSCC validating cohort, we confirmed that low NR1H3 expression level was independent factor of poor OS (HR=1.295, 95% CI: 1.064 - 1.576) and it had the ability to predict poor RFS (log-rank test, P=0.0059).

Conclusions: Low NR1H3 expression level is an independent prognostic factor of poor OS, and can also predict worse RFS in MIBC patients. Our “TCGA filtrating and local database validating” model can help reveal more prognostic biomarkers and cast a new light in understanding certain gene function in MIBC.

Periostin expression in intra-tumoral stromal cells is prognostic and predictive for colorectal carcinoma via creating a cancer-supportive niche

Periostin (POSTN) expression in cancer cells and circulation has been related to poor prognosis of colorectal carcinoma (CRC). However, the role of POSTN expressed in intra-tumoral stroma on CRC progression remains largely unknown. This study enrolled 1098 CRC patients who received surgical treatment in Shanghai and Guangzhou, Mainland China. In Shanghai cohort, immunohistochemistry score of stromal POSTN expression increased consecutively from adjacent mucosa, primary CRC tissues, to metastatic CRC tissues (P < 0.001), while medium- and high-stromal POSTN expression, rather than epithelial POSTN expression, independently predicted unfavorable prognoses of CRC, adjusted for covariates including TNM stage and postoperative chemotherapy in multivariate Cox models. The results in Shanghai cohort were faithfully replicated in Guangzhou cohort. Stromal POSTN expression dose-dependently predicted an unfavorable prognosis of stage III CRC patients with postoperative chemotherapy in both cohorts. POSTN derived from colonic fibroblasts or recombinant POSTN significantly promoted proliferation, anchorage independent growth, invasion, and chemo-resistance of CRC cells; whereas these effects were counteracted via targeting to PI3K/Akt or Wnt/β-catenin signaling pathway. CRC cell RKO-derived factor(s) significantly induced POSTN production in colonic fibroblasts and autocrine POSTN promoted proliferation, migration, and anchorage independent growth of fibroblasts. Conclusively, stromal POSTN is prognostic and predictive for CRC via creating a niche to facilitate cancer progression. Targeting POSTN-induced signaling pathways may be therapeutic options for metastatic or chemoresistant CRC.

The orphan nuclear receptor NR4A2 is part of a p53-microRNA-34 network

Nuclear receptor subfamily 4 group A member 2 (NR4A2) is an orphan nuclear receptor that is over-expressed in cancer and promotes cell proliferation, migration, transformation, and chemoresistance. Increased expression and function of NR4A2 have been attributed to various signaling pathways, but little is known about microRNA (miRNA) regulation of NR4A2 in cancer. To investigate the posttranscriptional regulation of NR4A2, we used a 3′ untranslated region (UTR) reporter screen and identified miR-34 as a putative regulator of NR4A2. By using computer predictions, we identified and confirmed an miRNA recognition element in the 3′ UTR of NR4A2 that was responsible for miR-34–mediated suppression. We next demonstrated that overexpression of exogenous miR-34 or activation of the p53 pathway, which regulates endogenous miR-34 expression, decreased NR4A2 expression. Consistent with previous reports, overexpression of NR4A2 blocked the induction of p53 target genes, including mir-34a. This was a phenotypic effect, as NR4A2 overexpression could rescue cells from p53-induced inhibition of proliferation. In summary, our results are the first characterization of a cancer-related miRNA capable of regulating NR4A2 and suggest a network and possible feedback mechanism involving p53, miR-34, and NR4A2.

Clinical significance of flotillin-1 overexpression in human gastric cancer

AIM: To investigate the expression of flotillin-1 (FLOT1) protein in gastric cancer and analyze their correlation with pathological characteristics and prognosis.

METHODS: We detected the FLOT1 expression in fresh gastric cancer samples and matched adjacent noncancerous tissue samples by real-time florescence quantitative PCR (qRT-PCR) (n = 16) and Western blot analysis (n = 16). Additionally, immunohistochemistry was performed to examine FLOT1 protein expression in paraffin-embedded gastric carcinoma tissues and matched normal specimens from 187 gastric cancer patients. Statistical analyses were applied to evaluate the associations of FLOT1 expression with clinical parameters and prognosis.

RESULTS: FLOT1 mRNA and protein levels were evidently up-regulated in gastric cancer tissues compared with adjacent non-cancerous tissue samples (13/16; 12/16). FLOT1 expression in gastric cancer tissues was significantly higher than that in corresponding adjacent normal tissues (92.35% vs 26.67%, P < 0.05). Expression of FLOT1 in tumor tissue was not significantly associated with gender, age, tumor size, differentiation status or tumor location. However, elevated FLOT1 expression was strongly correlated with depth of invasion (P = 0.000), lymph node metastasis (P = 0.000), distant metastasis (P = 0.000), and AJCC stage (P = 0.016). Elevated FLOT1 cases had a poor prognosis.

CONCLUSION: FLOT1 expression is significantly correlated with depth of invasion and distant metastasis. FLOT1 may be used as an early diagnostic marker and therapeutic target for gastric carcinoma.

Inflammation-related factors predicting prognosis of gastric cancer

Gastric cancer (GC), which is mainly induced by Helicobacter pylori (H. pylori) infection, is one of the leading causes of cancer-related death in the developing world. Active inflammation initiated by H. pylori infection and maintained by inherent immune disorders promotes carcinogenesis and postoperative recurrence. However, the presence with H. pylori in tumors has been linked to a better prognosis, possibly due to the induction of antitumor immunity. Tumor infiltrations of tumor-associated macrophages, myeloid-derived suppressor cells, neutrophils, Foxp3⁺ regulatory T cells are correlated with poor prognosis. Tumor infiltrating CD8⁺ cytotoxic T lymphocytes, dendritic cells, and CD45RO T cells are generally associated with good prognosis of GC, although some subsets of these immune cells have inverse prognosis prediction values. High ratios of Foxp3⁺/CD4⁺ and Foxp3⁺/CD8⁺ in tumors are associated with a poor prognosis; whereas high Th1/Th2 ratio in tumors predicts a good prognosis. High levels of interleukin (IL)-6, IL-10, IL-32, and chemokine C-C motif ligands (CCL)7 and CCL21 in circulation, high expression of CXC chemokine receptor 4, chemokine C-C motif receptor (CCR)3, CCR4, CCR5, CCR7, hypoxia-inducible factor-1α, signal transducer activator of transcription-3, cyclooxygenase-2, and orphan nuclear receptor 4A2 in tumors are associated with an unfavorable prognosis. Increased serum levels of matrix metalloproteinases (MMP)-3, MMP-7, and MMP-11 and increased levels of MMP-9, MMP-12, and MMP-21 in tumors are consistently associated with poor survival of GC. Further emphasis should be put on the integration of these biomarkers and validation in large cohorts for personalized prediction of GC postoperative prognosis.

Role of imaging in predicting response to neoadjuvant chemotherapy in gastric cancer

With the proven overall benefit of neoadjuvant chemotherapy in patients with locally advanced gastric cancer, there has come a need to discriminate responders from non-responders. In this article, the current role of anatomical and molecular imaging in the prediction of response to neoadjuvant therapy in gastric cancer is outlined and future prospects are discussed.

Minireview: role of orphan nuclear receptors in cancer and potential as drug targets

The nuclear orphan receptors for which endogenous ligands have not been identified include nuclear receptor (NR)0B1 (adrenal hypoplasia congenita critical region on chromosome X gene), NR0B2 (small heterodimer partner), NR1D1/2 (Rev-Erbα/β), NR2C1 (testicular receptor 2), NR2C2 (testicular receptor 4), NR2E1 (tailless), NR2E3 (photoreceptor-specific NR [PNR]), NR2F1 chicken ovalbumin upstream promoter transcription factor 1 (COUP-TFI), NR2F2 (COUP-TFII), NR2F6 (v-erbA-related protein), NR4A1 (Nur77), NR4A2 (Nurr1), NR4A3 (Nor1), and NR6A1 (GCNF). These receptors play essential roles in development, cellular homeostasis, and disease including cancer where over- or underexpression of some receptors has prognostic significance for patient survival. Results of receptor knockdown or overexpression in vivo and in cancer cell lines demonstrate that orphan receptors exhibit tumor-specific pro-oncogenic or tumor suppressor-like activity. For example, COUP-TFII expression is both a positive (ovarian) and negative (prostate and breast) prognostic factor for cancer patients; in contrast, the prognostic activity of adrenal hypoplasia congenita critical region on chromosome X gene for the same tumors is the inverse of COUP-TFII. Functional studies show that Nur77 is tumor suppressor like in acute leukemia, whereas silencing Nur77 in pancreatic, colon, lung, lymphoma, melanoma, cervical, ovarian, gastric, and some breast cancer cell lines induces one or more of several responses including growth inhibition and decreased survival, migration, and invasion. Although endogenous ligands for the orphan receptors have not been identified, there is increasing evidence that different structural classes of compounds activate, inactivate, and directly bind several orphan receptors. Thus, the screening and development of selective orphan receptor modulators will have important clinical applications as novel mechanism-based agents for treating cancer patients overexpressing one or more orphan receptors and also for combined drug therapies.