Ribonucleotide Reductase Regulatory Subunit M2 Research Articles

Comprehensive Analysis of Immune-Related Metabolic Genes in Lung Adenocarcinoma.

PurposeThe immunotherapy of lung adenocarcinoma (LUAD) has received much attention in recent years and metabolic reprogramming is linked to immune infiltration in the tumor microenvironment. Therefore, it is indispensable to dissect the role of immune-related metabolic genes in lung adenocarcinoma.MethodsIn this study, we screened immune-related genes by Pearson correlation. The function of these genes was explored by gene ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis. The differently expressed immune-related genes were analyzed by Limma. Furthermore, the LUAD patients were clustered based on immune-related genes through consensus clustering. The Unicox was used to identify survival-immune-related metabolic genes. The Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was used to optimize the gene sets. A prediction model was constructed and tested. The potential therapeutic target was selected based on two criteria, these immune-related metabolic genes that were highly expressed in tumor tissues and negatively correlated with the survival of patients in LUAD. Quantitative real‐time PCR (qRT‐PCR) was used for in vitro experimental validations.ResultsWe identified 346 immune-related genes, mainly involved in arachidonic acid metabolism and peroxisome proliferator-activated receptor (PPAR) signaling. Moreover, a total of 141 immune-related genes were dysregulated between tumor and normal tissues. We clustered three subtypes of LUAD based on immune-related metabolic genes and these subtypes exhibited different survival and immune status. We found Ribonucleotide Reductase Regulatory Subunit M2 (RRM2) as a potential therapeutic target, which is positively correlated with the cyclin-dependent kinase family of genes.ConclusionWe comprehensively analyzed the immune-related metabolic genes in LUAD. RRM2 was determined as a promising metabolic checkpoint for lung adenocarcinoma.

MiR-200c-3p and miR-485-5p overexpression elevates cisplatin sensitivity and suppresses the malignant phenotypes of non-small cell lung cancer cells through targeting RRM2.

BackgroundThis study intended to investigate the potential mechanism of microRNA‐200c‐3p (miR‐200c‐3p) and miR‐485‐5p in mediating the cisplatin (DDP) resistance in non–small cell lung cancer (NSCLC).MethodsQuantitative real‐time polymerase chain reaction (qRT‐PCR) was applied to measure the expression of miR‐200c‐3p, miR‐485‐5p, and ribonucleotide reductase regulatory subunit M2 (RRM2) messenger RNA (mRNA). 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay was used to analyze the DDP resistance and the proliferation of NSCLC cells. Colony formation assay was used to assess cell proliferation. Transwell assays were used to evaluate cell migration and invasion. The target relationship between RRM2 and miR‐200c‐3p or miR‐485‐5p was verified using dual‐luciferase reporter assay. The protein level of RRM2 was measured using Western blot assay. Animal experiments were conducted to analyze the roles of miR‐200c‐3p and miR‐485‐5p in the DDP resistance of xenograft tumors in vivo.ResultsMiR‐200c‐3p and miR‐485‐5p were both downregulated in DDP‐resistant NSCLC tissues and cell lines. Overexpressing miR‐200c‐3p or miR‐485‐5p suppressed the DDP resistance and malignant behaviors of NSCLC cells. MiR‐200c‐3p played a synergistic role with miR‐485‐5p in regulating the chemo‐resistance and biological behaviors NSCLC cells. RRM2 was confirmed as a target of miR‐200c‐3p and miR‐485‐5p. RRM2 silencing restrained the DDP resistance and progression of NSCLC. RRM2 overexpression partly reversed miR‐200c‐3p or miR‐485‐5p‐induced influences in NSCLC cells. The overexpression of miR‐200c‐3p or miR‐485‐5p aggravated DDP‐mediated suppressive effect on tumor growth in vivo.ConclusionMiR‐200c‐3p or miR‐485‐5p enhanced the DDP sensitivity and suppressed the malignant behaviors of NSCLC cells partly through targeting RRM2.

LncRNA PART1 Stimulates the Development of Ovarian Cancer by Up-regulating RACGAP1 and RRM2.

Ovarian cancer (OC) is a kind of gynecologic malignancy with a high mortality rate. Long non-coding RNAs (lncRNAs) have been reported to exert regulatory roles in multiple diseases. However, the role of lncRNA prostate androgen-regulated transcript 1 (PART1) has not been investigated in the development of OC. In this study, from RT-qPCR analysis, we discovered that PART1 demonstrated high expression in OC cells. Moreover, data from functional assays manifested that PART1 reduction hindered the proliferative, migratory, and invasive capabilities of OC cells. In vivo uncovered that PART1 knockdown impeded OC tumor growth. Furthermore, from the experimental results of RNA pull down, RIP, and luciferase reporter assays, we discovered that PART1 served as a sponge for microRNA-6884-5p (miR-6884-5p) to modulate the expression of Rac GTPase activating protein 1 (RACGAP1) and ribonucleotide reductase regulatory subunit M2 (RRM2). Finally, rescue assays proved that overexpression of RACGAP1 or RRM2 abrogated the suppressive role of PART1 knockdown on OC cell malignant behaviors. RACGAP1 and RRM2 were also revealed to act as oncogenes in OC cells. In summary, our research verified the PART1/miR-6884-5p/RACGAP1/RRM2 axis in OC cells, which signified that PART1 might act as a novel biomarker in OC.

MicroRNA-582-3p targeting ribonucleotide reductase regulatory subunit M2 inhibits the tumorigenesis of hepatocellular carcinoma by regulating the Wnt/β-catenin signaling pathway

ABSTRACT Hepatocellular carcinoma (HCC) is an important cause of death worldwide. MicroRNA (miRNA)-mediated gene silencing is involved in tumor biology. In this study, we aimed to elucidate the function and mechanism of action of miR-582-3p in HCC. We performed reverse transcription-quantitative polymerase chain reaction and western blotting to detect the expression levels of miR-582-3p, ribonucleotide reductase regulatory subunit M2 (RRM2), and markers of the Wnt/β-catenin signaling pathway (Wnt, Gsk-3β, β-catenin, and C-myc). The potential binding between miR-582-3p and RRM2 was confirmed using a dual-luciferase reporter assay. The proliferative and migratory capacities of the cells were evaluated using the cell counting kit-8 and wound-healing assays, respectively. Mouse models were used to validate the role of miR-582-3p in vivo. We observed the downregulation of miR-582-3p levels in HCC tumors and cell lines. Its upregulation in Huh7 and Hep 3B cells impaired their proliferation and migration, and the in vivo results showed suppressed tumor growth. Additionally, miR-582-3p upregulation also reduced the expression levels of Wnt, β-catenin, and C-myc, but enhanced the expression levels of glycogen synthase kinase-3β, both in vitro and in vivo. miR-582-3p targeted RRM2, and a negative correlation was observed in its expression patterns in HCC. Furthermore, RRM2 overexpression aggravated the proliferative and migratory capabilities of Hep3B and Huh7 cells and triggered Wnt/β-catenin signaling. However, miR-582-3p depleted RRM2 expression, thereby attenuating the oncogenic effects of RRM2. In conclusion, our results demonstrated that miR-582-3p binds to RRM2 to regulate the Wnt/β-catenin signaling pathway, thereby blocking the progression of HCC.

Targeting matrix metallopeptidase 2 by hydroxyurea selectively kills acute myeloid mixed-lineage leukemia

Oncogene-induced tumorigenesis results in the variation of epigenetic modifications, and in addition to promoting cell immortalization, cancer cells undergo more intense cellular stress than normal cells and depend on other support genes for survival. Chromosomal translocations of mixed-lineage leukemia (MLL) induce aggressive leukemias with an inferior prognosis. Unfortunately, most MLL-rearranged (MLL-r) leukemias are resistant to conventional chemotherapies. Here, we showed that hydroxyurea (HU) could kill MLL-r acute myeloid leukemia (AML) cells through the necroptosis process. HU target these cells by matrix metallopeptidase 2 (MMP2) deficiency rather than subordinate ribonucleotide reductase regulatory subunit M2 (RRM2) inhibition, where MLL directly regulates MMP2 expression and is decreased in most MLL-r AMLs. Moreover, iron chelation of HU is also indispensable for inducing cell stress, and MMP2 is the support factor to protect cells from death. Our preliminary study indicates that MMP2 might play a role in the nonsense-mediated mRNA decay pathway that prevents activation of unfolding protein response under innocuous endoplasmic reticulum stress. Hence, these results reveal a possible strategy of HU application in MLL-r AML treatment and shed new light upon HU repurposing.

Uridine dynamic administration affects the circadian variation of bile acid metabolism in high-fat-diet-fed mice

High-fat diet (HFD) is demonstrated to disturb the bile acid metabolism. The rhythm of bile acid metabolism can also be affected by uridine, whose metabolism exhibits a daily rhythm. However, the mechanism of dynamic uridine administration affecting bile acid during HFD remains unclear. In this study, C57BL/6J mice were fed HFD (the control group; CON) or HFD with oral administration of uridine in the daytime (DUR) and nighttime (NUR) to investigate the mechanism of the effect of uridine on the bile acid. This study showed that the mRNA expression of uridine transporters and circadian clock genes in the jejunum was affected by zeitgeber time (ZT) (P < 0.001). Genes related to the metabolism of pyrimidines in the liver showed a high dependence on daily rhythm (P < 0.01), and DUR remarkably up-regulated the expression of ribonucleotide reductase regulatory subunit M2 (RRM2) (P < 0.05) compared to the CON group. Importantly, the mRNA expression of bile acids nuclear receptors, bile acid synthesis, and transporters in the liver showed significantly rhythmically changed (P < 0.05), and the expression of cholesterol 7-alpha-hydroxylase (CYP7A1), fibroblast growth factor receptor 4 (FGFR4), Na+/taurocholate co transporting polypeptide (NTCP), and bile salt export pump (BSEP) mRNAs of mice with uridine administration increased significantly (P < 0.05). The mRNA expression of the transporters of cholesterol and bile acids in the ileum was also affected by ZT (P < 0.01) and significantly dependent on uridine administration (P < 0.05). The expression of FXR and SHP was significantly affected by ZT and uridine, respectively. In conclusion, dynamic administration of uridine could regulate the rhythm of gene expression of pyrimidine and bile acid metabolism in the liver and ileum of HFD-fed mice, which contributed to the further study of circadian rhythmic physiological and pathological changes of bile acids.

The Protective Effects of Lactoferrin on Aflatoxin M1-Induced Compromised Intestinal Integrity.

Aflatoxin M1 (AFM1), the only toxin with maximum residue levels in milk, has adverse effects on the intestinal barrier, resulting in intestinal inflammatory disease. Lactoferrin (LF), one of the important bioactive proteins in milk, performs multiple biological functions, but knowledge of the protective effects of LF on the compromised intestinal barrier induced by AFM1 has not been investigated. In the present study, results using Balb/C mice and differentiated Caco-2 cells showed that LF intervention decreased AFM1-induced increased intestinal permeability, improved the protein expression of claudin-3, occludin and ZO-1, and repaired the injured intestinal barrier. The transcriptome and proteome were used to clarify the underlying mechanisms. It was found that LF reduced the intestinal barrier dysfunction caused by AFM1 and was associated with intestinal cell survival related pathways, such as cell cycle, apoptosis and MAPK signaling pathway and intestinal integrity related pathways including endocytosis, tight junction, adherens junction and gap junction. The cross-omics analysis suggested that insulin receptor (INSR), cytoplasmic FMR1 interacting protein 2 (CYFIP2), dedicator of cytokinesis 1 (DOCK1) and ribonucleotide reductase regulatory subunit M2 (RRM2) were the potential key regulators as LF repaired the compromised intestinal barrier. These findings indicated that LF may be an alternative treatment for the compromised intestinal barrier induced by AFM1.

DDRE-34. RIBONUCLEOTIDE REDUCTASE REGULATORY SUBUNIT M2 AS A DRIVER OF GLIOBLASTOMA TMZ-RESISTANCE THROUGH MODULATION OF dNTP PRODUCTION

Abstract Glioblastoma (GBM) remains one of the most resistant and fatal forms of cancer. Previous studies examine pre- and post-tumor recurrence; however, it is incredibly difficult to study tumor evolution during therapy where resistance develops. To investigate this, our lab performed a single-cell RNA-sequencing screen before, during, and after temozolomide-based (TMZ) chemotherapy in a patient-derived xenograft (PDX) model in vivo. Our analysis found 149 genes uniquely expressed during TMZ-therapy compared to pre- and post-therapy (p&amp;lt; 0.0001). Of these, the ribonucleotide reductase (RNR) gene family stood out due to the preferential switch to Ribonucleotide Reductase Regulatory Subunit M2 (RRM2) during therapy. Classically, RRM2, or its isoform RRM2B, forms a complex with RRM1 to create an RNR, mediating deoxynucleoside triphosphate (dNTP) production. Our single-cell data revealed that GBM cells rely on RRM1-RRM2 interaction during therapy, but switch to RRM1-RRM2B in post-therapy recurrent GBM. In vitro, RRM2-knockdown cells increased TMZ susceptibility, whereas RRM1- and RRM2B-knockdowns were more resistant to TMZ (p&amp;lt; 0.001). Immunocytochemistry found elevated yH2AX fluorescence in RRM2-knockdowns after TMZ treatment, signifying reduced DNA repair capacity compared to the control (p&amp;lt; 0.001). To understand the mechanism of RRM2-mediated chemoresistance, targeted metabolomics was applied to quantify dNTP signatures during TMZ-therapy. In response to TMZ, dCTP and dGTP production in GBM cells increased 100-fold and 80-fold respectively (p&amp;lt; 0.001). RRM2-knockdowns produced significantly less dCTP and dGTP (p&amp;lt; 0.0001). By supplementing RRM2-knockdowns with dCTP and dGTP, TMZ-susceptibility was rescued, suggesting that RRM2 drives chemoresistance by promoting production of these two nucleotides. In vivo, following intracranial injection of GBM cells, mice treated with the RRM2 inhibitor Triapine with TMZ survived longer than those treated with TMZ alone, indicating promising clinical opportunities in targeting RRM2 (p&amp;lt; 0.0001). Overall, our data present a novel understanding of how RRM2 activity is altered during therapeutic stress to counteract TMZ-induced DNA damage.

Screening and predicted value of potential biomarkers for breast cancer using bioinformatics analysis

Breast cancer is the most common cancer and the leading cause of cancer-related deaths in women. Increasing molecular targets have been discovered for breast cancer prognosis and therapy. However, there is still an urgent need to identify new biomarkers. Therefore, we evaluated biomarkers that may aid the diagnosis and treatment of breast cancer. We searched three mRNA microarray datasets (GSE134359, GSE31448 and GSE42568) and identified differentially expressed genes (DEGs) by comparing tumor and non-tumor tissues using GEO2R. Functional and pathway enrichment analyses of the DEGs were performed using the DAVID database. The protein–protein interaction (PPI) network was plotted with STRING and visualized using Cytoscape. Module analysis of the PPI network was done using MCODE. The associations between the identified genes and overall survival (OS) were analyzed using an online Kaplan–Meier tool. The redundancy analysis was conducted by DepMap. Finally, we verified the screened HUB gene at the protein level. A total of 268 DEGs were identified, which were mostly enriched in cell division, cell proliferation, and signal transduction. The PPI network comprised 236 nodes and 2132 edges. Two significant modules were identified in the PPI network. Elevated expression of the genes Discs large-associated protein 5 (DLGAP5), aurora kinase A (AURKA), ubiquitin-conjugating enzyme E2 C (UBE2C), ribonucleotide reductase regulatory subunit M2(RRM2), kinesin family member 23(KIF23), kinesin family member 11(KIF11), non-structural maintenance of chromosome condensin 1 complex subunit G (NCAPG), ZW10 interactor (ZWINT), and denticleless E3 ubiquitin protein ligase homolog(DTL) are associated with poor OS of breast cancer patients. The enriched functions and pathways included cell cycle, oocyte meiosis and the p53 signaling pathway. The DEGs in breast cancer have the potential to become useful targets for the diagnosis and treatment of breast cancer.

Identification of Five Hub Genes as Key Prognostic Biomarkers in Liver Cancer via Integrated Bioinformatics Analysis

Simple SummaryLiver cancer is one of the most common cancers; however, the molecular mechanisms of liver tumorigenesis and progression are not completely understood. In the current study, we combined several bioinformatic approaches (differential gene expression analyses, weighted gene co-expression network analysis, pathway and gene-disease network enrichment) to identify potential hub genes and molecular pathways that contribute to liver cancer onset and development. The results revealed DNA topoisomerase II alpha (TOP2A), ribonucleotide reductase regulatory subunit M2 (RRM2), never in mitosis-related kinase 2 (NEK2), cyclin-dependent kinase 1 (CDK1), and cyclin B1 (CCNB1) as the hub genes for liver cancer. Subsequent validation suggested TOP2A, RRM2, NEK2, CDK1, and CCNB1 as the prognostic biomarkers of liver cancer.Liver cancer is one of the most common cancers and the top leading cause of cancer death globally. However, the molecular mechanisms of liver tumorigenesis and progression remain unclear. In the current study, we investigated the hub genes and the potential molecular pathways through which these genes contribute to liver cancer onset and development. The weighted gene co-expression network analysis (WCGNA) was performed on the main data attained from the GEO (Gene Expression Omnibus) database. The Cancer Genome Atlas (TCGA) dataset was used to evaluate the association between prognosis and these hub genes. The expression of genes from the black module was found to be significantly related to liver cancer. Based on the results of protein–protein interaction, gene co-expression network, and survival analyses, DNA topoisomerase II alpha (TOP2A), ribonucleotide reductase regulatory subunit M2 (RRM2), never in mitosis-related kinase 2 (NEK2), cyclin-dependent kinase 1 (CDK1), and cyclin B1 (CCNB1) were identified as the hub genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses showed that the differentially expressed genes (DEGs) were enriched in the immune-associated pathways. These hub genes were further screened and validated using statistical and functional analyses. Additionally, the TOP2A, RRM2, NEK2, CDK1, and CCNB1 proteins were overexpressed in tumor liver tissues as compared to normal liver tissues according to the Human Protein Atlas database and previous studies. Our results suggest the potential use of TOP2A, RRM2, NEK2, CDK1, and CCNB1 as prognostic biomarkers in liver cancer.

M1 Macrophage-Derived Exosomes Loaded with Gemcitabine and Deferasirox against Chemoresistant Pancreatic Cancer.

Pancreatic cancer is a malignant disease with high mortality and poor prognosis due to lack of early diagnosis and low treatment efficiency after diagnosis. Although Gemcitabine (GEM) is used as the first-line chemotherapeutic drug, chemoresistance is still the major problem that limits its therapeutic efficacy. Here in this study, we developed a specific M1 macrophage-derived exosome (M1Exo)-based drug delivery system against GEM resistance in pancreatic cancer. In addition to GEM, Deferasirox (DFX) was also loaded into drug carrier, M1Exo, in order to inhibit ribonucleotide reductase regulatory subunit M2 (RRM2) expression via depleting iron, and thus increase chemosensitivity of GEM. The M1Exo nanoformulations combining both GEM and DFX significantly enhanced the therapeutic efficacy on the GEM-resistant PANC-1/GEM cells and 3D tumor spheroids by inhibiting cancer cell proliferation, cell attachment and migration, and chemoresistance to GEM. These data demonstrated that M1Exo loaded with GEM and DFX offered an efficient therapeutic strategy for drug-resistant pancreatic cancer.

Emerging role of SIRT2 in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is one of the most devastating cancer types, accounting for >80% of lung cancer cases. The median relative survival time of patients with NSCLC is <1 year. Lysine acetylation is a major post-translational modification that is required for various biological processes, and abnormal protein acetylation is associated with various diseases, including NSCLC. Protein deacetylases are currently considered cancer permissive partly due to malignant cells being sensitive to deacetylase inhibition. Sirtuin 2 (SIRT2), a primarily cytosolic nicotinamide adenine dinucleotide-dependent class III protein deacetylase, has been shown to catalyze the removal of acetyl groups from a wide range of proteins, including tubulin, ribonucleotide reductase regulatory subunit M2 and glucose-6-phosphate dehydrogenase. In addition, SIRT2 is also known to possess lysine fatty deacylation activity. Physiologically, SIRT2 serves as a regulator of the cell cycle and of cellular metabolism. It has been shown to play important roles in proliferation, migration and invasion during carcinogenesis. It is notable that both oncogenic and tumor suppressive functions of SIRT2 have been described in NSCLC and other cancer types, suggesting a context-specific role of SIRT2 in cancer progression. In addition, inhibition of SIRT2 exhibits a broad anticancer effect, indicating its potential as a therapeutic for NSCLC tumors with high expression of SIRT2. However, due to the diverse molecular and genetic characteristics of NSCLC, the context-specific function of SIRT2 remains to be determined. The current review investigated the functions of SIRT2 during NSCLC progression with regard to its regulation of metabolism, stem cell-like features and autophagy.

Transcriptomic Analysis Reveals the MicroRNAs Responsible for Liver Regeneration Associated With Mortality in Alcohol-Associated Hepatitis.

We conducted a comprehensive serum transcriptomic analysis to explore the roles of microRNAs (miRNAs) in alcohol-associated hepatitis (AH) pathogenesis and their prognostic significance. Serum miRNA profiling was performed in 15 controls, 20 heavy drinkers without liver disease, and 65 patients with AH and compared to publicly available hepatic miRNA profiling in AH patients. Among the top 26 miRNAs, expression of miR-30b-5p, miR-20a-5p, miR-146a-5p, and miR-26b-5p were significantly reduced in both serum and liver of AH patients. Pathway analysis of the potential targets of these miRNAs uncovered the genes related to DNA synthesis and cell-cycle progression pathways, including ribonucleotide reductase regulatory subunit M2 (RRM2), cyclin D1 (CCND1), cyclin D2 (CCND2), MYC proto-oncogene (MYC), and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1). We found a significant increase in the protein expression of RRM2, CCND1, and CCND2, but not MYC and PMAIP1, in AH patients who underwent liver transplantation; miR-26b-5p and miR-30b-5p inhibited the 3'-UTR (untranslated region) luciferase activity of RRM2 and CCND2, and miR-20a-5p reduced the 3'-UTR luciferase activity of CCND1 and CCND2. During a median follow-up of 346days, 21% of AH patients died; these patients had higher body mass index (BMI), Model for End-Stage Liver Disease (MELD), and serum miR-30b-5p, miR-20a-5p, miR-146a-5p, and miR-26b-5p than those who survived. Cox regression analysis showed that BMI, MELD score, miR-20a-5p, miR-146a-5p, and miR-26b-5p predicted mortality. Patients with AH attempt to deal with hepatocyte injury by down-regulating specific miRNAs and up-regulating genes responsible for DNA synthesis and cell-cycle progression. Higher expression of these miRNAs, suggestive of a diminished capacity in liver regeneration, predicts short-term mortality in AH patients.

RRM2 silencing suppresses malignant phenotype and enhances radiosensitivity via activating cGAS/STING signaling pathway in lung adenocarcinoma

BackgroundAs one of the most common malignancy, lung adenocarcinoma (LUAD) is characterized by low 5-year survival rate. This research aimed to investigate the effects of ribonucleotide reductase regulatory subunit M2 (RRM2) on malignant biological behaviors and activation of cGAS/STING pathway. We also explored the synergistic sensitization mechanisms of RRM2 and radiotherapy.MethodsBioinformatic tools were used to evaluate the clinical significance of RRM2 in LUAD patients. The roles of RRM2 in malignant phenotype and DNA damage in LUAD cells were investigated with cell proliferation, colony formation, immunofluorescence, modified Boyden chamber and comet assays. The mouse models were used to evaluate the biological significance of RRM2 in vivo. Cytotoxic T cell infiltration was evaluated via flow cytometric analysis and immunohistochemistry staining in C57BL/6 mice. We also explored the synergistic effects of RRM2 silencing and radiation on LUAD cells with apoptosis assay and immunoblotting in vitro.ResultsBioinformatic analysis revealed that RRM2 had diagnostic values for LUAD patients. Higher levels of RRM2 predicted worse prognosis. RRM2 silencing inhibited LUAD cell proliferation, invasion and migration. RRM2 knockdown induced S phase arrest and DNA damage. RRM2 silencing induced cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway, and the downstream targets were regulated in a STING-dependent manner. Knockdown of RRM2 suppressed tumor growth in the xenograft tumor models. RRM2 deficiency increased CD8 + T cells in the tumor tissues and spleens. Furthermore, RRM2 silencing had synergistic effects with radiation on inhibiting cell proliferation and promoting apoptosis. Meanwhile, this combination promoted the activation of cGAS/STING signaling pathway synergistically, and simultaneously increased expression of IFNβ, CCL5 and CXCL10.ConclusionOur results demonstrated that RRM2 silencing had anti-tumor values and activated the cGAS/STING signaling pathway. RRM2 silencing increased CD8 + T cells infiltration. RRM2 silencing cooperated with radiation to inhibit LUAD cell proliferation, promote apoptosis and enhance the activation of cGAS/STING signaling pathway. RRM2 could be a promising target for tumor regression through cancer immunotherapy in LUAD.

Identification of potential oncogenes in triple-negative breast cancer based on bioinformatics analyses.

Triple-negative breast cancer (TNBC) is a subtype with high rates of metastasis, poor prognosis and limited therapeutic options. The present study aimed to identify the potential pivotal genes for prognosis and treatment in TNBC. A total of two microarray expression datasets, GSE38959 and GSE65212, were downloaded from the Gene Expression Omnibus database, and RNA-sequencing data of breast cancer from The Cancer Genome Atlas database were analyzed to screen out differentially expressed genes (DEGs) between TNBC tissues and normal tissues. The intersection of DEGs was submitted to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. A protein-protein interaction (PPI) network was constructed and visualized using Cytoscape software. Furthermore, module, centrality and survival analyses were performed to identify the potential hub genes. Reverse transcription-quantitative (RT-q)PCR analysis was performed to detect the expression levels of key genes in TNBC samples, and 377 DEGs were identified. Functional analysis revealed that the DEGs were significantly involved in cell cycle process, nuclear division and the p53 signaling pathway. A PPI network was constructed with these DEGs, and 66 core genes with high centrality features in module 1 were selected. Relapse-free survival analysis confirmed that high expression levels of five genes [cyclin B1 (CCNB1), GINS complex subunit 2, non-SMC condensin I complex subunit G (NCAPG), minichromosome maintenance 4 (MCM4) and ribonucleotide reductase regulatory subunit M2 (RRM2)] were significantly associated with poor prognosis in TNBC. RT-qPCR analysis demonstrated that CCNB1, NCAPG, MCM4 and RRM2 were significantly upregulated in 25 TNBC tissues compared with adjacent normal breast tissues. Furthermore, gene set enrichment analysis revealed that CCNB1, NCAPG, MCM4 and RRM2 were closely associated with tumor proliferation. Taken together, these results suggest that CCNB1, NCAPG, MCM4 and RRM2 are associated with tumorigenesis and TNBC progression, and thus may act as promising prognostic biomarkers and therapeutic targets for TNBC.

MicroRNA-20a-5p suppresses tumor angiogenesis of non-small cell lung cancer through RRM2-mediated PI3K/Akt signaling pathway.

The current therapeutic strategies for non-small cell lung cancer (NSCLC) are limited and unsatisfactory. MicroRNAs (miRNAs) participate in tumor angiogenesis in NSCLC. The aim of this study was to investigate the role of miR-20a-5p (miR-20a) in human NSCLC metastasis. In the current study, bioinformatics analysis and RT-PCR were performed to examine the expression level of miR-20a in tissues of NSCLC patients and NSCLC cell lines, respectively. Western blot was performed to test the protein levels. Cell proliferation, migration and angiogenesis capacity were tested by 5-ethynyl-29-deoxyuridine (EdU) assay, transwell assay and tube formation assay, respectively. Dual-luciferase reporter assay (DLR) was used to confirm the interaction between miR-20a and paired ribonucleotide reductase regulatory subunit M2 (RRM2). We found that the expression of RRM2 was upregulated, while the expression of miR-20a was downregulated in cancer tissues compared with adjacent tissues in NSCLC patients. We also detected the expression level of RRM2 and miR-20a in NSCLC cell lines, showing A549 cell line exhibited the lowest expression level of miR-20a and highest expression level of RRM2. Overexpressed miR-20a not only dramatically suppressed NSCLC cells proliferation, endothelial cells migration and tube formation in vitro, but also inhibited tumor growth and angiogenesis in vivo. It was demonstrated that miR-20a suppressed NSCLC growth by inhibiting RRM2-mediated PI3K/Akt signaling pathway. These findings indicate that the novel identified miR-20a could function as a tumor suppressor in NSCLC through modulating the RRM2-mediated PI3K/Akt axis, and it could be a valid molecular target for NSCLC treatment.

770P Prognostic and predictive value of ribonucleotide reductase subunit family M1/M2 in urothelial carcinoma

Ribonucleotide reductase catalytic subunit M1 (RRM1) and ribonucleotide reductase regulatory subunit M2 (RRM2) are involved in DNA replication and DNA repair. Preclinical and clinical evidence has shown that high RRM1 expression is associated with resistance to gemcitabine and cisplatin in certain cancer types, but the predictive and prognostic value of RRM1 and RRM2 in urothelial cancer (UC) remains to be studied. Microarray datasets related to gene expression in UC were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases and supplementary data from published papers. Kaplan-Meier analyses were performed for mRNA expression and clinical outcome correlations. The associations between mRNA expression and clinicopathological parameters were analysed using Chi-square/Fisher exact tests and Mann-Whitney U test. In the UC cohort from the TCGA (n = 407), high expression of RRM1 (RRM1-H) and RRM2 (RRM2-H) were significantly associated with worse outcomes. The median OS in RRM1-H population was 28.80 m vs 98.47 m (HR=2, 95%CI 1.3-3.1, P=0.003), while the differences in RRM2 expression levels were also associated with distinct clinical outcomes (median OS of patient with RRM2-H, 27.30 m vs 47.43 m, HR=1.5, 95%CI 1.1-2, P=0.008). To further evaluate the prognostic value of RRM1 and RRM2, another 2 cohorts with adequate information on mRNA expression and survival were analysed (GSE13507, the CNUH cohort, 165 primary UC patients with surgical resection of a transitional cell carcinoma; and GSE32894; the SSH cohort, 224 patients undergoing transurethral resection) and results showed that RRM1-H or RRM2-H were associated with a poor OS in UC (HR, 2.7; 95% CI, 1.3-1.5; P =0.005 in CNUH cohort. HR, 6.6; 95% CI, 2.03-22.0; P < 0.001 in SSH cohort). Patients with high transcript abundance of RRM1 and RRM2 were validated to show worse survival benefits (P < 0.05), which indicate that RRM1 and RRM2 are potential prognostic biomarkers. We also conducted an analysis of an immunotherapy cohort (IMvigor 210, a single-arm, multicentre, phase 2 study, included 348 patients with atezolizumab treatment), in this cohort, patients with RRM1-H or RRM2-H were associated with higher Objective Response Rate (ORR) (24%), and associated with a better tendency for OS in UC(HR 0.68, 95%CI 0.45-1.00, P= 0.061). Further analysis indicated that RRM1 and RRM2 expression levels were positively correlated with PD-L1 expression, tumour-immune phenotypes (P < 0.05 for All). High RRM1 or RRM2 expression levels were a potential prognostic biomarker in UC patients across different disease courses. In addition, RRM1 or RRM2 expression levels showed some predictive value for patients with UC receiving immunotherapy.

Bitter melon juice intake with gemcitabine intervention circumvents resistance to gemcitabine in pancreatic patient-derived xenograft tumors.

Chemoresistance to gemcitabine (GEM)-a frontline chemotherapeutic, resulting from its dysfunctional uptake and metabolism in cancer cells, is a major contributing factor for failed therapy in pancreatic cancer (PanC) patients. Therefore, there is an urgent need for agents that could reverse GEM resistance and allow continued chemosensitivity to the drug. We employed natural nontoxic agent (with anti-PanC potential) bitter melon juice (BMJ) and GEM to examine their combinatorial benefits against tumorigenesis of PanC patient-derived xenograft (PDX)-pancreatic ductal adenocarcinomas explants PDX272 (wild-type KRAS), PDX271 (mutant KRAS and SMAD4), and PDX266 (mutant KRAS). Anti-PanC efficacy of single agents vs combination in the three tumor explants, both at the end of active dosing regimen and following a drug-washout phase were compared. In animal studies, GEM alone treatment significantly inhibited PDX tumor growth, but effects were not sustained, as GEM-treated tumors exhibited regrowth posttreatment termination. However, combination-regimen displayed enhanced and sustained efficacy. Mechanistic assessments revealed that overcoming GEM resistance by coadministration with BMJ was possibly due to modulation of GEM transport/metabolism pathway molecules (ribonucleotide reductase regulatory subunit M1, human equilibrative nucleoside transporter 1, and deoxycytidine kinase). Study outcomes, highlighting significantly higher and sustained efficacy of GEM in combination with BMJ, make a compelling case for a clinical trial in PanC patients, wherein BMJ could be combined with GEM to target and overcome GEM resistance. In addition, given their specific effectiveness against KRAS-mutant tumors, this combination could be potentially beneficial to a broader PanC patient population.

Human equilibrative nucleoside transporter-1 (hENT1) and ribonucleotide reductase regulatory subunit M1 (RRM1) expression; do they have survival impact to pancreatic cancer?

Backgrounds/AimsGemcitabine is still one of adjuvant options in chemotherapeutic agent for pancreatic ductal adenocarcinoma (PDAC). Integral membrane transporter protein and intracellular enzymes including human equilibrative nucleoside transporter 1 (hENT1), deoxycytidine kinase (dCK), ribonucleotide reductase (RR) M1, and M2 are known as important factors for chemosensitivity of gemcitabine. We aimed to investigate the correlation between these key molecules and 5-year actual survival in PDAC patients.MethodsThe expression of intratumoral hENT1, dCK, RRM1, and RRM2 was assessed immunohistochemically in 160 PDAC patients underwent surgical resection. Association between clininopathologic factors, immunohistochemical results, and overall survival were analyzed.ResultsAdjuvant chemotherapy including concurrent chemoradiotherapy was not associated with overall survival (HR, 0.92; 95% CI, 0.65-1.31; p=0.658). High hENT1 expression group did not show statistical survival difference, compared with all others (HR, 1.16; 95% CI, 0.82-1.65, p=0.396). Gemcitabine therapy and high hENT1 group was compared with all other patients, and no difference in overall survival was identified (HR, 0.99; 95% CI, 0.68-1.42; p=0.940). And, gemcitabine therapy and high hENT1 group did not differ statistically from gemcitabine therapy and low hENT1 expression (HR, 0.92; 95% CI, 0.55-1.56; p=0.764). The intensity of dCK, RRM1, and RRM2 expression was not associated with overall survival (p=0.413, p=0.138 and p=0.061) in univariate analysis.ConclusionsThe expression of hENT1, dCK, RRM1 and RRM2 may not be associated with overall survival for patients with pancreatic cancer on gemcitabine adjuvant therapy. These proteins and other factors that may interact with or confound these results should be investigated in the near future.

Functional Genomic Screen in Mesothelioma Reveals that Loss of Function of BRCA1-Associated Protein 1 Induces Chemoresistance to Ribonucleotide Reductase Inhibition.

Loss of function of BRCA1-associated protein 1 (BAP1) is observed in about 50% of malignant pleural mesothelioma (MPM) cases. The aim of this study was to investigate whether this aspect could be exploited for targeted therapy. A genetically engineered model was established expressing either functional or nonfunctional BAP1, and whole-genome siRNA synthetic lethality screens were performed assessing differentially impaired survival between the two cell lines. The whole-genome siRNA screen unexpectedly revealed 11 hits (FDR < 0.05) that were more cytotoxic to BAP1-proficient cells. Two actionable targets, ribonucleotide reductase (RNR) catalytic subunit M1 (RRM1) and RNR regulatory subunit M2 (RRM2), were validated. In line with the screen results, primary mesothelioma (BAP1 +/-) overexpressing BAP1 C91A (catalytically dead mutant) was more resistant to RNR inhibition, while BAP1 knockdown in the BAP1-proficient cell lines rescued the cells from their vulnerability to RNR depletion. Gemcitabine and hydroxyurea were more cytotoxic in BAP1-proficient cell line-derived spheroids compared with BAP1 deficient. Upregulation of RRM2 upon gemcitabine and hydroxyurea treatment was more profound in BAP1 mut/del cell lines. Increased lethality mediated by RNR inhibition was observed in NCI-H2452 cells reconstituted with BAP1-WT but not with BAP1 C91A. Upregulation of RRM2 in NCI-H2452-BAP1 WT spheroids was modest compared with control or C91A mutant. Together, we found that BAP1 is involved in the regulation of RNR levels during replication stress. Our observations reveal a potential clinical application where BAP1 status could serve as predictive or stratification biomarker for RNR inhibition-based therapy in MPM.