MicroRNA-181a functions as an oncomir in gastric cancer by targeting the tumour suppressor gene ATM

Environmental factors in gastric carcinogenesis and preventive intervention strategies

Gastric cancer, a significant global health concern, arises from a complex interplay of genetic and environmental factors. Helicobacter pylori (H. pylori) infection is a major risk factor that can be mitigated through eradication strategies. Epstein-Barr virus (EBV) infection causes a distinct subtype of gastric cancer called EBV-associated gastric cancer. The gastric microbiome, a dynamic ecosystem, is also involved in carcinogenesis, particularly dysbiosis and specific bacterial species such as Streptococcus anginosus. Long-term use of proton pump inhibitors and potassium-competitive acid blockers also increases the risk of gastric cancer, whereas non-steroidal anti-inflammatory drugs including aspirin may have a protective effect. Smoking significantly increases the risk, and cessation can reduce it. Dietary factors such as high intake of salt, processed meats, and red meat may increase the risk, whereas a diet rich in fruits and vegetables may be protective. Extracellular vesicles, which are small membrane-bound structures released by cells, modulate the tumor microenvironment and may serve as biomarkers for risk stratification and as therapeutic targets in gastric cancer. This review highlights the multifaceted etiology of gastric cancer and its risk factors and emphasizes the importance of a multi-pronged approach to prevention including H. pylori eradication and modification of lifestyle factors, as well as the potential of microbiome-based and EV-based interventions. Further research is needed to refine risk stratification and to develop personalized prevention strategies.

miR-181a: regulatory roles, cancer-associated signaling pathway disruptions, and therapeutic potential

INTRODUCTION

microRNA-181a (miR-181a) is a crucial post-transcriptional regulator of many mRNA transcripts and noncoding-RNAs, influencing cell proliferation, cancer cell stemness, apoptosis, and immune responses. Its abnormal expression is well-characterized in numerous cancers, establishing it as a significant genomic vulnerability and biomarker in cancer research.

AREAS COVERED

Here, we summarize miR-181a's correlation with poor patient outcomes across numerous cancers and the mechanisms governing miR-181a's activity and processing. We comprehensively describe miR-181a's involvement in multiple regulatory cancer signaling pathways, cellular processes, and the tumor microenvironment. We also discuss current therapeutic approaches to targeting miR-181a, highlighting their limitations and future potential.

EXPERT OPINION

miR-181a is a clinically relevant pan-cancer biomarker with potential as a therapeutic target. Its regulatory control of tumorigenic signaling pathways and immune responses positions it as a promising candidate for personalized treatments. The success of miR-181a as a target relies on the development of specific therapeutics platforms. Future research on miR-181a's role in the tumor microenvironment and the RNA binding proteins that regulate its stability will help uncover new techniques to targeting miR-181a. Further research into miR-181a serum levels in patients undergoing therapy will help to better stratify patients and enhance therapeutic success.

Pinostrobin, a fingerroot compound, regulates miR-181b-5p and induces acute leukemic cell apoptosis

Pinostrobin (PN) is the most abundant flavonoid found in fingerroot. Although the anti-leukemic properties of PN have been reported, its mechanisms are still unclear. MicroRNAs (miRNAs) are small RNA molecules that function in posttranscriptional silencing and are increasingly being used in cancer therapy. The aims of this study were to investigate the effects of PN on proliferation inhibition and induction of apoptosis, as well as the involvement of miRNAs in PN-mediated apoptosis in acute leukemia. The results showed that PN reduced cell viability and induced apoptosis in acute leukemia cells via both intrinsic and extrinsic pathways. A bioinformatics approach and Protein-Protein Interaction (PPI) network analysis revealed that ataxia-telangiectasia mutated kinase (ATM), one of the p53 activators that responds to DNA damage-induced apoptosis, is a crucial target of PN. Four prediction tools were used to predict ATM-regulated miRNAs; miR-181b-5p was the most likely candidate. The reduction in miR-181b-5 after PN treatment was found to trigger ATM, resulting in cellular apoptosis. Therefore, PN could be developed as a drug for acute leukemia; in addition, miR-181b-5p and ATM may be promising therapeutic targets.

Functional importance of glucose transporters and chromatin epigenetic factors in Glioblastoma Multiforme (GBM): possible therapeutics

Glioblastoma Multiforme (GBM) is an aggressive brain cancer affecting glial cells and is chemo- and radio-resistant. Glucose is considered the most vital energy source for cancer cell proliferation. During metabolism, hexose molecules will be transported into the cells via transmembrane proteins known as glucose transporter (GLUT). Among them, GLUT-1 and GLUT-3 play pivotal roles in glucose transport in GBM. Knockdown studies have established the role of GLUT-1, and GLUT-3 mediated glucose transport in GBM cells, providing insight into GLUT-mediated cancer signaling and cancer aggressiveness. This review focussed on the vital role of GLUT-1 and GLUT-3 proteins, which regulate glucose transport. Recent studies have identified the role of GLUT inhibitors in effective cancer prevention. Several of them are in clinical trials. Understanding and functional approaches towards glucose-mediated cell metabolism and chromatin epigenetics will provide valuable insights into the mechanism of cancer aggressiveness, cancer stemness, and chemo-resistance in Glioblastoma Multiforme (GBM). This review summarizes the role of GLUT inhibitors, micro-RNAs, and long non-coding RNAs that aid in inhibiting glucose uptake by the GBM cells and other cancer cells leading to the identification of potential therapeutic, prognostic as well as diagnostic markers. Furthermore, the involvement of epigenetic factors, such as microRNAs, in regulating glycolytic genes was demonstrated.

Signaling pathways and therapeutic interventions in gastric cancer

Gastric cancer (GC) ranks fifth in global cancer diagnosis and fourth in cancer-related death. Despite tremendous progress in diagnosis and therapeutic strategies and significant improvements in patient survival, the low malignancy stage is relatively asymptomatic and many GC cases are diagnosed at advanced stages, which leads to unsatisfactory prognosis and high recurrence rates. With the recent advances in genome analysis, biomarkers have been identified that have clinical importance for GC diagnosis, treatment, and prognosis. Modern molecular classifications have uncovered the vital roles that signaling pathways, including EGFR/HER2, p53, PI3K, immune checkpoint pathways, and cell adhesion signaling molecules, play in GC tumorigenesis, progression, metastasis, and therapeutic responsiveness. These biomarkers and molecular classifications open the way for more precise diagnoses and treatments for GC patients. Nevertheless, the relative significance, temporal activation, interaction with GC risk factors, and crosstalk between these signaling pathways in GC are not well understood. Here, we review the regulatory roles of signaling pathways in GC potential biomarkers, and therapeutic targets with an emphasis on recent discoveries. Current therapies, including signaling-based and immunotherapies exploited in the past decade, and the development of treatment for GC, particularly the challenges in developing precision medications, are discussed. These advances provide a direction for the integration of clinical, molecular, and genomic profiles to improve GC diagnosis and treatments.

Higher ATM expression in lymphoblastoid cell lines from centenarian compared with younger women

With increased life expectancies in developed countries, cancer rates are becoming more common among the elderly. Cancer is typically driven by a combination of germline and somatic mutations accumulating during an individual's lifetime. Yet, many centenarians reach exceptionally old age without experiencing cancer. It was suggested that centenarians have more robust DNA repair and mitochondrial function, allowing improved maintenance of DNA stability. In this study, we applied real-time quantitative PCR to examine the expression of ATM in lymphoblastoid cell lines (LCLs) from 15 healthy female centenarians and 24 younger female donors aged 21-88 years. We observed higher ATM mRNA expression of in LCLs from female centenarians compared with both women aged 21-48 years (FD = 2.0, p = .0016) and women aged 56-88 years (FD = 1.8, p = .0094. Positive correlation was found between ATM mRNA expression and donors age (p = .0028). Levels of hsa-miR-181a-5p, which targets ATM, were lower in LCLs from centenarians compared with younger women. Our findings suggest a role for ATM in protection from age-related diseases, possibly reflecting more effective DNA repair, thereby reducing somatic mutation accumulation during aging. Further studies are required for analyzing additional DNA repair pathways in biosamples from centenarians and younger age men and women.

Autophagy inhibits cancer stemness in triple-negative breast cancer via miR-181a-mediated regulation of ATG5 and/or ATG2B

Autophagy has a dual role in the maintenance of cancer stem cells (CSCs), but the precise relationship between autophagy and cancer stemness requires further investigation. In this study, it was found that luminal and triple‐negative breast cancers require distinct therapeutic approaches because of their different amounts of autophagy flux. We identified that autophagy flux was inhibited in triple‐negative breast cancer (TNBC) CSCs. Moreover, miRNA‐181a (miR‐181a) expression is upregulated in both TNBC CSCs and patient tissues. Autophagy‐related 5 (ATG5) and autophagy‐related 2B (ATG2B) participate in the early formation of autophagosomes and were revealed as targets of miR‐181a. Inhibition of miR‐181a expression led to attenuation of TNBC stemness and an increase in autophagy flux. Furthermore, treatment with curcumin led to attenuation of cancer stemness in TNBC CSCs; the expression of ATG5 and ATG2B was enhanced and there was an increase of autophagy flux. These results indicated that ATG5 and ATG2B are involved in the suppression of cancer stemness in TNBC. In summary, autophagy inhibits cancer stemness through the miR‐181a‐regulated mechanism in TNBC. Promoting tumor‐suppressive autophagy using curcumin may be a potential method for the treatment of TNBC.

Expression of miR-181a in Circulating Tumor Cells of Ovarian Cancer and Its Clinical Application

Objective: To determine the possibility of early diagnosis and prognosis of ovarian cancer (OC) via detecting miR-181a in circulating tumor cells (CTCs) of OC and to solve clinical difficulties in OC tissue sample collection. Methods: EpCAM liposome magnetic beads (Ep-LMBs) were prepared by the reverse-phase evaporation method, and the performance of EpCAM was characterized. The cytotoxicity assay was detected by the MTT assay, and CTC capture efficiency was determined using OC cell lines. Blood and tissue samples were collected from 30 patients with OC and 30 normal ovarian tissue samples were selected. Expression of miR-181a in CTCs and tissue samples was measured by real-time fluorescence quantitative PCR (RT-qPCR) with U6 as an internal reference. Expression of miR-181a was interfered in OC cells and its relative expression was measured. Results: Ep-LMBs were successfully prepared with high stability. Cellular assays showed that these Ep-LMBs could capture up to 80% of OC cells. RT-qPCR showed that the expression of miR-181a was increased in OC tissues compared with that in normal ovarian tissues, and the relative expressions of miR-181a in cancerous tissues and CTCs were comparable. Correlation analysis with clinical characteristics revealed that miR-181a expression was correlated with the stage and metastasis of OC and the difference was statistically significant. Conclusion: MiR-181a may be involved in the development and progression of OC as an oncogene. Detection of miR-181a in Ep-LMB-captured CTCs is an effective and feasible alternative method for early diagnosis and prognostic evaluation of OC other than tissue tests.

miR-181a, delivered by hypoxic PTC-secreted exosomes, inhibits DACT2 by downregulating MLL3, leading to YAP-VEGF-mediated angiogenesis

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer, and angiogenesis plays critical roles in its recurrence and metastasis. In this study, we investigated the effects of hypoxia-induced exosomal microRNA-181 (miR-181a) from PTC on tumor growth and angiogenesis. Thyroid-cancer-related differentially expressed miR-181a was identified by microarray-based analysis in the Gene Expression Omnibus (GEO) database. We validated that miR-181a was highly expressed in PTC cells and even more so in cells cultured under hypoxic conditions, which also augmented exosome secretion from PTC cells. Exosomes extracted from PTC cells with manipulated miR-181a and mixed-lineage leukemia 3 (MLL3) were subjected to normoxic or hypoxic conditions. Human umbilical vein endothelial cells (HUVECs) were transfected with miR-181a inhibitor/mimic or small interfering RNA (siRNA)-MLL3 or treated with exosomes from hypoxic PTC cells. Hypoxic exosomal miR-181a delivery promoted proliferation and capillary-like network formation in HUVECs. Mechanistically, miR-181a targeted and inhibited MLL3. Furthermore, miR-181a downregulated DACT2 and upregulated YAP and vascular endothelial growth factor (VEGF). Further, hypoxic exosomal miR-181a induced angiogenesis and tumor growth in vivo, which was reversed by hypoxic exosomal miR-181a inhibitor. In conclusion, exosomal miR-181a from hypoxic PTC cells promotes tumor angiogenesis and growth through MLL3 and DACT2 downregulation, as well as VEGF upregulation.

MiR-181 Family Modulates Osteopontin in Glioblastoma Multiforme

Simple Summary

MicroRNAs can silence a broad set of target genes that may benefit heterogeneous tumors like glioblastoma. We have previously shown that osteopontin has an oncogenic role and may have immune modulatory effects on macrophages. In the current study, we used miRNAs to target osteopontin in tumor cells and modulate immune cells to elicit an antitumor effect. Intravenous delivery of miR-181a to immune competent mice bearing intracranial glioblastoma demonstrated a 22% increase in median survival duration relative to that of control mice. The overexpression of miR-181a in tumor cells led to decreased OPN production and proliferation and increased apoptosis in vitro, and increased survival duration of the mice when compared to its controls. miR-181a controls osteopontin expression in tumor cells by regulating their proliferation and apoptosis.

Abstract

MiRNAs can silence a wide range of genes, which may be an advantage for targeting heterogenous tumors like glioblastoma. Osteopontin (OPN) plays both an oncogenic role in a variety of cancers and can immune modulate macrophages. We conducted a genome wide profiling and bioinformatic analysis to identify miR-181a/b/c/d as potential miRNAs that target OPN. Luciferase assays confirmed the binding potential of miRNAs to OPN. Expression levels of miR-181a/b/c/d and OPN were evaluated by using quantitative real-time PCR and enzyme-linked immunosorbent assay in mouse and human glioblastomas and macrophages that showed these miRNAs were downregulated in Glioblastoma associated CD11b+ cells compared to their matched blood CD14b+ cells. miRNA mimicking and overexpression using lentiviruses showed that MiR-181a overexpression in glioblastoma cells led to decreased OPN production and proliferation and increased apoptosis in vitro. MiR-181a treatment of immune competent mice bearing intracranial glioblastoma demonstrated a 22% increase in median survival duration relative to that of control mice.

Plasma miR-181a-5p Downregulation Predicts Response and Improved Survival After FOLFIRINOX in Pancreatic Ductal Adenocarcinoma

OBJECTIVE

The aim of the study was to identify plasma microRNA (miRNA) biomarkers for stratifying and monitoring patients with locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC) treated with FOLFIRINOX, and to investigate their functional roles.

SUMMARY BACKGROUND DATA

FOLFIRINOX has become a standard therapy for patients with advanced PDAC and can be used to potentially downstage disease. However, only a subset of patients respond, and biomarkers to guide decision-making are urgently needed.

METHODS

We used microarray-based profiling to discover deregulated miRNAs in pre- and postchemotherapy plasma samples from patients based on their progression-free survival (PFS) after FOLFIRINOX. Nine candidate plasma miRNAs were validated in an independent cohort (n = 43). The most discriminative plasma miRNA was correlated with clinicopathological factors and survival, and also investigated in an additional cohort treated with gemcitabine plus nab-paclitaxel. Expression patterns were further evaluated in matched tumor tissues. In vitro studies explored its function, key downstream gene-targets, and interaction with 5-fluorouracil, irinotecan, and oxaliplatin.

RESULTS

Plasma miR-181a-5p was significantly downregulated in non-progressive patients after FOLFIRINOX. In multivariate analysis, this decline correlated with improved PFS and overall survival, especially when combined with CA19-9 decline [hazard ratio (HR) = 0.153, 95% confidence interval (CI), 0.067-0.347 and HR = 0.201, 95% CI, 0.070-0.576, respectively]. This combination did not correlate with survival in patients treated with gemcitabine plus nab-paclitaxel. Tissue expression of miR-181a-5p reflected plasma levels. Inhibition of miR-181a-5p coupled with oxaliplatin exposure in pancreatic cell lines decreased cell viability.

CONCLUSIONS

Plasma miR-181a-5p is a specific biomarker for monitoring FOLFIRINOX response. Decline in plasma miR-181a-5p and CA19-9 levels is associated with better prognosis after FOLFIRINOX and may be useful for guiding therapeutic choices and surgical exploration.

microRNA-181 serves as a dual-role regulator in the development of human cancers

MicroRNAs (miRNAs) as the regulatory short noncoding RNAs are involved in a wide array of cellular and molecular processes. They negatively regulate gene expression and their dysfunction is correlated with cancer development through modulation of multiple signaling pathways. Therefore, these molecules could be considered as novel biomarkers and therapeutic targets for more effective management of human cancers. Recent studies have demonstrated that the miR-181 family is dysregulated in various tumor tissues and plays a pivotal role in carcinogenesis. They have been shown to act as oncomirs or tumor suppressors considering their mRNA targets and to be involved in cell proliferation, apoptosis, autophagy, angiogenesis and drug resistance. Additionally, these miRNAs have been demonstrated to exert their regulatory effects through modulating multiple signaling pathways including PI3K/AKT, MAPK, TGF-b, Wnt, NF-κB, Notch pathways. Given that, in this review, we briefly summarise the recent studies that have focused on the roles of miRNA-181 family as the multifunctional miRNAs in tumorigenesis and cancer development. These miRNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets in human cancer gene therapy.

MicroRNAs, DNA damage response and ageing

Ageing is a multifactorial and integrated gradual deterioration affecting the most of biological process of cells. MiRNAs are differentially expressed in the cellular senescence and play important role in regulating of genes expression involved in features of ageing. The perception of miRNAs functions in ageing regulation can be useful in clarifying the mechanisms underlying ageing and designing of therapeutic strategies. The preservation of genomic integrity through DNA damage response (DDR) is related to the process of cellular senescence. The recent studies have shown that miRNAs has directly regulated the expression of numerous proteins in DDR pathways. In this review study, DDR pathways, miRNA biogenesis and functions, current finding on DDR regulations, molecular biology of ageing and the role of miRNAs in these processes have been studied. Finally, a brief explanation about the therapeutic function of miRNAs in ageing regarding its regulation of DDR has been provided.

Therapeutic Potential of the miRNA-ATM Axis in the Management of Tumor Radioresistance

The ataxia-telangiectasia mutated (ATM) protein kinase is widely known for its function as a chief mobilizer of the DNA damage response (DDR) upon DNA double-strand breaks. ATM orchestrates the DDR by modulating the expression of various miRNAs through several mechanisms. On the other hand, a set of miRNAs contribute to tight regulation of ATM by directly targeting the 3'-untranslated region of ATM mRNA. This review addresses the therapeutic application and molecular mechanisms that underlie the intricate interactions between miRNAs and ATM. It also describes therapeutic delivery of miRNAs in different environments such as hypoxic tumor microenvironments.

Altered expression of miR-181 affects cell fate and targets drug resistance-related mechanisms

MicroRNAs (miRNAs) are non-coding transcripts which regulate genetic and epigenetic events by interfering with mRNA translation. miRNAs are involved in regulation of cell fate due to their ability of interfering with physiological or pathological processes. In this review paper, we evaluate the role of miR-181 family members as prognostic or diagnostic markers or therapeutic targets in malignant pathologies in connection with the main hallmarks of cancer that are modulated by the family. Also, we take over the dual role of this family in dependency with the tumour suppressor and oncogenic features presented in cell and cancer type specific manner. Restoration of the altered expression levels contributes to the activation of cell death pathways or to a reduction in the invasion and migration mechanism; moreover, the mechanism of drug resistance is also modulated by miR-181 sequences with important applications in therapeutic strategies for malignant cells sensitisation. Overall, the main miR-181 family regulatory mechanisms are presented in a cancer specific context, emphasizing the possible clinical application of this family in terms of novel diagnosis and therapy approaches.

Serum microRNA-381: A Potential Marker for Early Diagnosis of Gastric Cancer

PURPOSE

The purpose of this study was to explore the potential early diagnostic value of serum microRNA-381(miRNA-381) in patients with gastric cancer (GC).

MATERIALS AND METHODS

Patients with advanced gastric cancer (AGC) and early gastric cancer (EGC), as well as healthy individuals, were enrolled in this study. Expression of miRNA-381 in serum was detected using real-time quantitative PCR. Electrochemiluminescence analysis was used to investigate the expression of classic tumor markers, including carbohydrate antigen (CA) 199, CA724, and carcinoembryonic antigen. Finally, receiver operating characteristic curve and Kaplan-Meier analysis were used to determine the value of miRNA-381 in clinical diagnosis of GC.

RESULTS

miRNA-381 was differentially expressed among the study groups. AUC analysis showed that the sensitivity and specificity of serum miRNA-381 in the diagnosis of GC were superior to those of other tumor markers. Furthermore, low levels of miRNA-381 expression were positively correlated with lymph node metastasis and AGC. Finally, Kaplan-Meier survival analysis showed that down-regulation of miRNA-381 was associated with lymph node metastasis and the development of GC.

CONCLUSION

miRNA381, which was down-regulated in GC, might be a novel early diagnosis marker for patients with GC.

Combined analysis of miRNA-181a with phase angle derived from bioelectrical impedance predicts radiotherapy-induced changes in body composition and survival of male patients with head and neck cancer

BACKGROUND

Nutritional deficits developing as an effect of applied radiotherapy (RTH) negatively affect patients' quality of life, survival, and therapy outcomes. We demonstrated novel approach to prediction of RTH-induced changes in body composition of patients with head and neck cancer using phase angle (PA) derived from bioelectrical impedance in combination with miRNA-181a expression.

RESULTS

Patients with simultaneous presence of low PA and high miRNA expression were at a significantly higher risk of decreasing the fat-free mass index (FFMI) <14.9 kg/m² (odds ratio [OR] = 5.14; P = .02), FFM < 44.7 kg (OR = 6.20; P = .04), and lean mass (OR = 10.0; P = .04) during the therapy period. Receiver operating curve analysis allowed to predict changes in FFMI, lean mass, and FFM with area under the curve calculation over 0.700. The simultaneous presence of high miRNA and low PA negatively affected patients' survival (OR = 5.12; P = .02).

CONCLUSION

Evaluation of PA in combination with miRNA demonstrates higher diagnostic accuracy and predictive value for detecting RTH-induced changes in body composition of patients with cancer.

Effects of miR-181a-5p abnormal expression on zebrafish (Danio rerio) vascular development following triclosan exposure

Triclosan (TCS), one of the important bactericides, is widely used in personal care products, and its chronic exposure leads to severe toxic effects on the growth and development of blood vessels in zebrafish (Danio rerio). Herein, we screened out three differentially expressed miRNAs (miR-181a-5p, miR-132-3p and miR-128-3p) by sequencing and qRT-PCR analyses of 4-96-hpf TCS-exposed zebrafish, among which miR-181a-5p was found to regulate many signaling pathways involved in fatty acid biosynthesis and phosphatidylimositol signaling systems. By O-dianisidine staining, TCS-exposure resulted in decreased distribution of red blood cells and induced blood hypercoagulable state and thrombotic effects. Defective subintestinal veins (SIVs), and decreased branching and curvature of blood vessels were observed with increasing TCS-exposure concentrations. After microinjection of miR-181a-5p mimic and inhibitor, zebrafish malformation type and percentage were prominently increased such as distorted SIV vessels along with reduced venation and abnormal branches by ALP staining. Overexpressed miR-181a-5p had a greater effect on development and branching patterns of arteries and veins than its knockdown. By laser confocal microscopy observation, the 72-hpf Tg (flk1: mCherry) zebrafish obviously displayed vascular proliferation and ablation in the miR-181a-5p mimic group. Microinjection of miR-181a-5p mimics and inhibitors led to abnormal expressions (20-50%) of two key target genes (pax2a and vash2) by WISH, and increased malformation percentages (18-45%) by IOD analysis. Overexpression of vash2 led to the inhibitory or promoting effects on the expression of PI3K signaling pathway-related genes, proving that the effect of vash2 on development of blood vessels could be realized by inhibiting PI3K signaling pathway. These observations lay theoretical foundation for deep insight into the molecular mechanisms on TCS-induced cardiovascular diseases.

MicroRNA-181a Functions as an Oncogene in Gastric Cancer by Targeting Caprin-1

MicroRNA-181a (miRNA-181a) is a multifaceted miRNA implicated in various cellular processes, particularly in cell fate determination and cellular invasion. It is frequently expressed aberrantly in human tumors and shows opposing functions in different types of cancers. In this study, we found that miRNA-181a is overexpressed in Gastric cancer (GC) tissues. Clinical and pathological analyses revealed that the expression of miRNA-181a is correlated with tumor size, lymph node metastasis, distant metastasis, and TNM stage. Kaplan-Meier analysis indicated that overexpression of miRNA-181a is associated with poor overall survival of patients with GC. Moreover, miRNA-181a is overexpressed in GC cells, and downregulation of miRNA-181a induced cell apoptosis and suppressed the proliferation, invasion, and metastasis of GC cells both in vitro and in vivo. Target prediction and luciferase reporter assay showed that caprin-1 was a direct target of miRNA-181a. Downregulation of caprin-1 expression resulted in a converse change with miRNA-181a in GC. Spearman’s correlation test confirmed that the expression of miRNA-181a expression was inversely correlated with that of caprin-1 in GC cells. Furthermore, the expression of caprin-1 increased after downregulation of miRNA-181a in the GC cells. Caprin-1 siRNA can rescue the oncogenic effect of miRNA-181a on GC cell proliferation, apoptosis, migration, and invasion. These findings suggest that miRNA-181a directly inhibits caprin-1 and promotes GC development. miRNA-181a could be a target for anticancer drug development.

MEG2 is regulated by miR-181a-5p and functions as a tumour suppressor gene to suppress the proliferation and migration of gastric cancer cells

BACKGROUND

Protein-tyrosine phosphatase MEG2 (MEG2) is a classic tyrosine-specific protein tyrosine phosphatase (PTP). It has been reported that MEG2 participates in the carcinogenesis of the breast and liver. However, functions of MEG2 in gastric cancer remain poorly understood.

METHODS

We examined the expression of MEG2 protein by western blotting and that of miR-181a-5p by qRT-PCR. We used bioinformatic analyses to search for miRNAs that potentially target MEG2. We performed a luciferase reporter assay to investigate the interaction between miR-181a-5p and MEG2. In addition, we assessed the effects of MEG2 and miR-181a-5p on gastric cancer cells in vitro and in vivo.

RESULTS

We found that MEG2 is downregulated in human gastric cancer and that miR-181a-5p is predicted to be a potential regulator of MEG2. We also observed that expression of MEG2 is reversely correlated with that of miR-181a-5p in gastric cancer. Moreover, we observed that MEG2 regulation by miR-181a-5p significantly suppresses the proliferation and migration of gastric cancer cells in vitro and decelerates tumour growth in vivo.

CONCLUSIONS

Our results revealed that MEG2 is a tumour suppressor gene and negatively regulated by miR-181a-5p in gastric cancer.

miR-181a-2 downregulates the E3 ubiquitin ligase CUL4A transcript and promotes cell proliferation

MiR-181a-2 plays a major role in cell proliferation both positively and negatively depending on tissue type by targeting several regulators 3'UTR regions. We have predicted several targets for miR-181a-2 through computational approaches and characterized one its interesting target, CUL4A, an E3 ubiquitin ligase. CUL4A regulates diverse functions in the cells including DNA repair, DNA replication, cell cycle, genomic stability through polyubiquitination of target proteins. Deregulation of both miR-181a-2 and CUL4A are reported in many cancerous cells, but the functional link between them is unknown. We show that miR-181a-5p binds to 3'UTR of CUL4A and regulates its transcripts levels in HEK293 cells through overexpression studies. In addition, by using MTT and Neutral red assays, we showed that miR-181a-2 overexpression increased the proliferation in HEK293 cells. Moreover, cell cycle analysis using flow cytometer revealed that an increase in S-phase cells upon the overexpression of miR-181a-2. Though several miRNAs are known to downregulate the CUL4A levels, here we show that miR-181a-2 also participates in the downregulation of CUL4A. Taken together, our data demonstrated that miR-181a-2 increases the cell proliferation in HEK293 cells possibly through the downregulation of CUL4A.

Dysregulation of non-coding RNAs in gastric cancer

Gastric cancer (GC) is one of the most common cancers in the world and a significant threat to the health of patients, especially those from China and Japan. The prognosis for patients with late stage GC receiving the standard of care treatment, including surgery, chemotherapy and radiotherapy, remains poor. Developing novel treatment strategies, identifying new molecules for targeted therapy, and devising screening techniques to detect this cancer in its early stages are needed for GC patients. The discovery of non-coding RNAs (ncRNAs), primarily microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), helped to elucidate the mechanisms of tumorigenesis, diagnosis and treatment of GC. Recently, significant research has been conducted on non-coding RNAs and how the regulatory dysfunction of these RNAs impacts the tumorigenesis of GC. In this study, we review papers published in the last five years concerning the dysregulation of non-coding RNAs, especially miRNAs and lncRNAs, in GC. We summarize instances of aberrant expression of the ncRNAs in GC and their effect on survival-related events, including cell cycle regulation, AKT signaling, apoptosis and drug resistance. Additionally, we evaluate how ncRNA dysregulation affects the metastatic process, including the epithelial-mesenchymal transition, stem cells, transcription factor activity, and oncogene and tumor suppressor expression. Lastly, we determine how ncRNAs affect angiogenesis in the microenvironment of GC. We further discuss the use of ncRNAs as potential biomarkers for use in clinical screening, early diagnosis and prognosis of GC. At present, no ideal ncRNAs have been identified as targets for the treatment of GC.

miR-181a-5p Inhibits Cancer Cell Migration and Angiogenesis via Downregulation of Matrix Metalloproteinase-14

Upregulation of matrix metalloproteinase MMP-14 (MT1-MMP) is associated with poor prognosis in cancer patients, but it is unclear how MMP-14 becomes elevated in tumors. Here, we show that miR-181a-5p is downregulated in aggressive human breast and colon cancers where its levels correlate inversely with MMP-14 expression. In clinical specimens, enhanced expression of MMP-14 was observed in cancer cells located at the invasive front of tumors where miR-181a-5p was downregulated relative to adjacent normal cells. Bioinformatics analyses defined a potential miR-181a-5p response element within the 3'-untranslated region of MMP-14 that was validated in reporter gene experiments. Ectopic miR-181a-5p reduced MMP-14 expression, whereas miR-181a-5p attenuation elevated MMP-14 expression. In support of a critical relationship between these two genes, miR-181a-5p-mediated reduction of MMP-14 levels was sufficient to decrease cancer cell migration, invasion, and activation of pro-MMP-2. Furthermore, this reduction in MMP-14 levels was sufficient to reduce in vivo invasion and angiogenesis in chick chorioallantoic membrane assays. Taken together, our results establish the regulation of MMP-14 in cancers by miR-181a-5p through a posttranscriptional mechanism, and they further suggest strategies to elevate miR-181a-5p to prevent cancer metastasis.

An integrated analysis of the effects of microRNA and mRNA on esophageal squamous cell carcinoma

Esophageal squamous cell cancer (ESCC) is an aggressive type of cancer with poor prognosis and leading to decreased quality of life. The identification of patients at increased risk of esophageal squamous cell cancer may improve current understanding of the role of micro (mi)RNA in tumorigenesis, since the miRNA pattern of these patients may be associated with tumorigenesis. In the present study, the miRNA and mRNA expression profiles of ESCC tissue samples and adjacent normal control tissue samples were obtained from two dependent GEO series. Bioinformatics analyses, including the use of the Gene Oncology and Kyoto Encyclopedia of Genes and Genomes databases, were used to identify genes and pathways, which were specifically associated with miRNA-associated ESCC oncology. A total of 17 miRNAs and 1,670 probes were differentially expressed in the two groups, and the differentially expressed miRNA and target interactions were analyzed. The mRNA of miRNA target genes were found to be involve 49 GO terms and 14 pathways. Of the genes differentially expressed between the two groups, miRNA-181a, miRNA-202, miRNA-155, FNDC3B, BNC2 and MBD2 were the most significantly altered and may be important in the regulatory network. In the present study, a novel pattern of differential miRNA-target expression was constructed, which with further investigation, may provide novel targets for diagnosing and understanding the mechanism of ESCC.

ATM has a major role in the double-strand break repair pathway dysregulation in sporadic breast carcinomas and is an independent prognostic marker at both mRNA and protein levels

BACKGROUND

Ataxia telangiectasia mutated (ATM) is a kinase that has a central role in the maintenance of genomic integrity by activating cell cycle checkpoints and promoting repair of DNA double-strand breaks (DSB). In breast cancer, a low level of ATM was correlated with poor outcome; however, the molecular mechanism of this downregulation is still unclear.

METHODS

We used qRT-PCR assay to quantify mRNA levels of ATM gene in 454 breast tumours from patients with known clinical/pathological status and outcome; reverse phase protein arrays (RPPA) were used to assess the levels of ATM and 14 proteins in 233 breast tumours.

RESULTS

ATM mRNA was associated with poor metastasis-free survival (MFS) (P=0.00012) on univariate analysis. ATM mRNA and protein levels were positively correlated (P=0.00040). A low level of ATM protein was correlated with poorer MFS (P=0.000025). ATM expression at mRNA or protein levels are independent prognostic factors on multivariate analysis (P=0.00046 and P=0.00037, respectively). The ATM protein level was positively correlated with the levels of six proteins of the DSB repair pathway: H2AX (P<0.0000001), XRCC5 (P<0.0000001), NBN (P<0.0000001), Mre11 (P=0.0000029), Rad50 (P=0.0064), and TP53BP1 (P=0.026), but not with proteins involved in other pathways that are altered in cancer. Low expression of ATM protein was significantly associated with high miR-203 expression (P=0.011).

CONCLUSION

We confirmed that ATM expression is an independent prognostic marker at both RNA and protein levels. We showed that alteration of ATM is involved in dysregulation of the DSB repair pathway. Finally, miR-203 may be responsible for downregulation of ATM in breast cancers.

MicroRNA regulates vascular endothelial growth factor expression in chondrosarcoma cells

BACKGROUND

Systemic treatments to prevent or treat chondrosarcoma metastasis are lacking and targeted therapy has yet to be developed. Hypoxia develops in tumors as they grow and hypoxia-related alterations in gene expression underlie some of the traits of cancer. One critical trait is the ability to induce sustained angiogenesis, which is usually related to expression of vascular endothelial growth factor (VEGF). A potential hypoxia-related mechanism resulting in altered gene expression involves microRNA. Little is known about microRNA expression in chondrosarcoma and its potential role in regulation of VEGF expression.

QUESTIONS/PURPOSES

Our purposes were (1) to determine if there is hypoxia-regulated microRNA overexpressed in chondrosarcoma; (2) if that contributes to increased VEGF expression; and (3) can VEGF expression be inhibited with a specific antagomir?

METHODS

MicroRNA expression was analyzed in two primary human chondrosarcomas and articular cartilage using array analysis and a cutoff of a fourfold difference in expression between tumor and normal tissue. The effects of hypoxia and hypoxia-inducible factor-1α (HIF-1α) transfection and silencing with siRNA on expression of candidate microRNAs were analyzed in chondrosarcoma cell line JJ. VEGF expression was measured with quantitative polymerase chain reaction and enzyme-linked immunosorbent assay after specific microRNA transfection and knockdown.

RESULTS

miR-181a was identified by array analysis and confirmed with quantitative reverse transcription-polymerase chain reaction, which showed that miR-181a was overexpressed in both human chondrosarcomas (33- and 55-fold) and the JJ cell line (sixfold) compared with cartilage and chondrocytes, respectively. In vitro, hypoxia and HIF-1α transfection each further increased miR-181a expression twofold in JJ cells. miR-181a transfection of JJ cells doubled expression of VEGF mRNA and increased secreted VEGF protein by 46% in normoxia, an effect that could be either direct or indirect. Similar enhancement of VEGF expression by miR-181a was found during hypoxia. Transfection with the antagomir anti-miR-181a decreased VEGF protein by 27% in normoxia and 23% in hypoxia.

CONCLUSIONS

miR-181a is a hypoxia-regulated microRNA that is overexpressed in chondrosarcoma and enhances VEGF expression, an effect that could be inhibited by anti-miR-181a.

CLINICAL RELEVANCE

Systemic treatment options for chondrosarcoma are limited. Antiangiogenic strategies could potentially be effective in limiting tumor progression. One method of inhibiting VEGF expression and associated angiogenesis could be an antagomir-based therapy targeted at miR-181a or other oncogenic microRNAs, although methods of systemic delivery are still under development. The effectiveness of antagomirs also needs to be compared with other antiangiogenic modalities in preclinical models.

Hsa-microRNA-181a is a regulator of a number of cancer genes and a biomarker for endometrial carcinoma in patients: a bioinformatic and clinical study and the therapeutic implication

The aberrant expression of human microRNA-181a-1 (hsa-miR-181a) has been implicated in the pathogenesis of various cancers, serving as an oncogene or a tumor suppressor. However, the role of hsa-miR-181a in the pathogenesis of endometrial carcinoma (EC) and its clinical significance are unclear. This study aimed to search for the molecular targets of hsa-miR-181a using bioinformatic tools and then determine the expression levels of hsa-miR-181a in normal, hyperplasia, and EC samples from humans. To predict the targets of hsa-miR-181a, ten different algorithms were used, including miRanda-mirSVR, DIANA microT v5.0, miRDB, RNA22 v2, TargetMiner, TargetScan 6.2, PicTar, MicroCosm Targets v5, and miRWALK. Two algorithms, TarBase 6.0 and miRTarBase, were used to identify the validated targets of hsa-miR-181a-5p (a mature product of hsa-miR-181a), and the web-based Database for Annotation, Visualization and Integrated Discovery (DAVID) 6.7 was used to provide biological functional interpretation of the validated targets of hsa-miR-181a-5p. A total of 78 formalin-fixed, paraffin-embedded tissue specimens from 65 patients and 13 healthy subjects were collected and examined, including normal endometrium (n=13), endometrial hyperplasia (n=18), and EC (37 type I and 10 type II EC cases). Our bioinformatic studies have showed that hsa-miR-181a might regulate a large number of target genes that are important in the regulation of critical cell processes, such as cell fate, cell survival, metabolism, and cell death. To date, 313 targets of hsa-miR-181a have been validated, and 22 of these targets are cancer genes. The precision of predictions by all the algorithms for hsa-miR-181a-1’s targets was low. Many of these genes are involved in tumorigenesis of various cancers, including EC, based on the DAVID and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In comparison with normal endometrial tissue, the expression level of hsa-miR-181a was significantly increased in type I and type II EC (P<0.05), and type II EC exhibited a significant higher expression level of hsa-miR-181a than that in type I EC (P<0.05). In addition, there was a significant increase in the expression level of hsa-miR-181a in type II EC compared with endometrial hyperplasia (P<0.05). Taken together, these results suggest that hsa-miR-181a may serve as an oncogene in endometrial tumorigenesis and that hsa-miR-181a might be used as a new biomarker in the prediction of prognosis of EC in clinical practice. More functional and mechanistic studies are needed to validate the role of hsa-miR-181a in the development, progression, and metastasis of EC.

The functional sites of miRNAs and lncRNAs in gastric carcinogenesis

Gastric cancer is one of the most common malignant diseases and has one of the highest mortality rates worldwide. Its molecular mechanisms are poorly understood. Recently, the functions of non-coding RNAs (ncRNAs) in gastric cancer have attracted wide attention. Although the expression levels of various ncRNAs are different, they may work together in a network and contribute to gastric carcinogenesis by altering the expression of oncogenes or tumor suppressor genes. They affect the cell cycle, apoptosis, motility, invasion, and metastasis. Dysregulated microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), including miR-21, miR-106, H19, and ANRIL, directly or indirectly regulate carcinogenic factors or signaling pathways such as PTEN, CDK, caspase, E-cadherin, Akt, and P53. Greater recognition of the roles of miRNAs and lncRNAs in gastric carcinogenesis can provide new insight into the mechanisms of tumor development and identify targets for anticancer drug development.

MicroRNAs Used in Combination with Anti-Cancer Treatments Can Enhance Therapy Efficacy

MicroRNAs (miRNAs), a recently discovered class of small non-coding RNAs, constitute a promising approach to anti-cancer treatments when they are used in combination with other agents. MiRNAs are evolutionarily conserved non-coding RNAs that negatively regulate gene expression by binding to the complementary sequence in the 3'-untranslated region (UTR) of target genes. MiRNAs typically suppress gene expression by direct association with target transcripts, thus decreasing the expression levels of target proteins. The delivery to cells of synthetic miRNAs that mimic endogenous miRNA targeting genes involved in the DNA-Damage Response (DDR) can perturb the process, making cells more sensitive to chemotherapy or radiotherapy. This review examines how cells respond to combined therapy and it provides insights into the role of miRNAs in targeting the DDR repair pathway when they are used in combination with chemical compounds or ionizing radiation to enhance cellular sensitivity to treatments.

Arsenic trioxide amplifies cisplatin toxicity in human tubular cells transformed by HPV-16 E6/E7 for further therapeutic directions in renal cell carcinoma

Human papillomavirus (HPV) DNA integrations may affect therapeutic responses in cancers through ATM network-related DNA damage response (DDR). We studied whether cisplatin-induced DDR was altered in human HK-2 renal tubular cells immortalized by HPV16 E6/E7 genes. Cytotoxicity assays utilized thiazolyl blue dye and DDR was identified by gene expression differences, double-strand DNA breaks, ATM promoter activity, and analysis of cell cycling and side population cells. After cisplatin, HK-2 cells showed greater ATM promoter activity indicating activation of this network, but DDR was muted, since little γH2AX was expressed, DNA strand breaks were absent and cells continued cycling. When HK-2 cells were treated with the MDM2 antagonist inducing p53, nutlin-3, or p53 transcriptional activator, tenovin-1, cell growth decreased but cisplatin toxicity was unaffected. By contrast, arsenic trioxide, which by inhibiting wild-type p53-induced phosphatase-1 that serves responses downstream of p53, and by depolymerizing tubulin, synergistically enhanced cisplatin cytotoxicity including loss of SP cells. Our findings demonstrated that HPV16 E6/E7 altered DDR through p53-mediated cell growth controls, which may be overcome by targeting of WIP1 and other processes, and thus should be relevant for treating renal cell carcinoma.

MiR-181a regulates blood-tumor barrier permeability by targeting Krüppel-like factor 6

Blood-tumor barrier (BTB) constitutes an efficient organization of tight junctions that impairs the delivery of therapeutic drugs. However, the methods and molecular mechanisms underlying the BTB opening remain elusive. MicroRNAs (miRNAs) have recently emerged as key regulators of various biologic processes and therapeutic targets. In this study, we have identified microRNA-181a (miR-181a) as a critical miRNA in opening BTB. MicroRNA-181a expression was upregulated in glioma endothelial cells (GECs), which were obtained by coculturing endothelial cells (ECs) with glioma cells. Overexpression of miR-181a resulted in an impaired and permeability increased BTB, and meanwhile reduced the expression of zonula occluden (ZO)-1, occludin, and claudin-5. Kruppel-like factor 6 (KLF6), a transcription factor of the zinc-finger family, was downregulated in GECs. Mechanistic investigations defined it as a direct and functional downstream target of miR-181a, which was involved in the regulation of BTB permeability and the expression of ZO-1, occludin, and claudin-5. Furthermore, luciferase assays and chromatin immunoprecipitation assays showed that KLF6 upregulated the promoter activities and interacted with the promoters of ZO-1, occludin, and claudin-5 in GECs. Collectively, we showed the possibility that overexpression of miR-181a contributes to the increased permeability of BTB by targeting KLF6, thereby revealing potential therapeutic targets for the treatment of brain gliomas.

MicroRNA and signaling pathways in gastric cancer

MicroRNAs (miRNAs) function as either oncogenes or tumor suppressors by inhibiting the expression of target genes, some of which are either directly or indirectly involved with canonical signaling pathways. The relationship between miRNAs and signaling pathways in gastric cancer is extremely complicated. In this paper, we determined the pathogenic mechanism of gastric cancer related to miRNA expression based on recent high-quality studies and then clarified the regulation network of miRNA expression and the correlated functions of these miRNAs during the progression of gastric cancer. We try to illustrate the correlation between the expression of miRNAs and outcomes of patients with gastric cancer. Understanding this will allow us to take a big step forward in the treatment of gastric cancer.

miR-143 inhibits NSCLC cell growth and metastasis by targeting Limk1

MicroRNAs (miRNAs) have essential roles in carcinogenesis and tumor progression. Here, we investigated the roles and mechanisms of miR-143 in non-small cell lung cancer (NSCLC). miR-143 was significantly decreased in NSCLC tissues and cell lines. Overexpression of miR-143 suppressed NSCLC cell proliferation, induced apoptosis, and inhibited migration and invasion in vitro. Integrated analysis identified LIM domain kinase 1 (Limk1) as a direct and functional target of miR-143. Overexpression of Limk1 attenuated the tumor suppressive effects of miR-143 in NSCLC cells. Moreover, miR-143 was inversely correlated with Limk1 expression in NSCLC tissues. Together, our results highlight the significance of miR-143 and Limk1 in the development and progression of NSCLC.