MicroRNA-21-5p promotes proliferation of gastric cancer cells through targeting SMAD7

Serum extracellular vesicle-derived miR-21-5p and miR-26a-5p as non-invasive diagnostic potential biomarkers for gastric cancer: A preliminary study

PURPOSE

Gastric cancer is the most common malignancy worldwide and is the third leading cause of cancer-related deaths, urgently requiring an early and non-invasive diagnosis. Circulating extracellular vesicles may emerge as promising biomarkers for the rapid diagnosis in a non-invasive manner.

METHODS

Using high-throughput small RNA sequencing, we profiled the small RNA population of serum-derived extracellular vesicles from healthy controls and gastric cancer patients. Differentially expressed microRNAs (miRNAs) were randomly selected and validated by reverse transcription-quantitative real-time polymerase chain reaction. Receiver operating characteristic curves were employed to assess the predictive value of miRNAs for gastric cancer.

RESULTS

In this study, 193 differentially expressed miRNAs were identified, of which 152 were upregulated and 41 were significantly downregulated. Among the differently expressed miRNA, the expression levels of miR-21-5p, miR-26a-5p, and miR-27a-3p were significantly elevated in serum-derived extracellular vesicles of gastric cancer patients. The miR-21-5p and miR-27a-3p were closely correlated with the tumor size. Moreover, the expression levels of serum miR-21-5p and miR-26a-5p were significantly decreased in gastric cancer patients after surgery.

CONCLUSIONS

The present study discovered the potential of serum miR-21-5p and miR-26a-5p as promising candidates for the diagnostic and prognostic markers of gastric cancer.

PDCD4 and MIR-21 are promising biomarkers in the follow-up of OED in liquid biopsies

This research aims to examine the impact of programmed cell death 4 (PDCD4), microRNA-21 (miR-21) and microRNA-208a (miR-208a) transcripts, and protein levels on oral epithelial dysplasia (OED) development in oral squamous cell carcinoma (OSCC).

METHODS

The research investigation involved the collection of saliva, blood, and tissue samples from a total of 20 patients diagnosed with OSCC, 15 patients diagnosed with OED, and 15 healthy individuals. PDCD4, miR-21, and miR-208a expression was performed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). PDCD4 protein levels were assessed using enzyme-linked immunosorbent assay (ELISA) in both saliva and blood samples. For statistical analysis, the Kruskal-Wallis test and the Spearmen rank test were utilised.

RESULTS

PDCD4 expression levels were considerably lower in patients with OSCC and OED (p < 0.05) in three biological samples. In contrast, miR-21 expression was higher in OED and OSCC patients. Patients with low PDCD4 mRNA levels and strong miR-21 expression had a significant connection (p < 0.05) with tumor size and depth.

CONCLUSIONS

Examining PDCD4 and miR-21 transcript levels may help detect the transition from OED to OSCC. This work suggests that PDCD4 and miR-21 expression levels in liquid biopsies may be biomarkers for OED monitoring in the future.

Akkermansia muciniphila improves gastric cancer treatment by modulating the immune microenvironment

Background: Gut microbiota is pivotal in tumor occurrence and development, and there is a close relationship between Akkermansia muciniphila (AKK) and cancer immunotherapy. Methods: The effects of AKK and its outer membrane proteins on gastric cancer (GC) were evaluated in vitro and in vivo using cell counting kit-8 assay, flow cytometry, western blotting, ELISA, immunohistochemistry and immunofluorescence. Results: AKK outer membrane protein facilitated apoptosis of GC cells and exerted an immunostimulatory effect (by promoting M1 polarization of macrophages, enhancing expression of cytotoxic T-lymphocyte-related cytokines and suppressing that of Treg-related cytokines). Additionally, AKK and its formulation could inhibit tumor growth of GC and enhance the infiltration of immune cells in tumor tissues. Conclusion: AKK could improve GC treatment by modulating the immune microenvironment.

MiRNA-21-5p induces chicken hepatic lipogenesis by targeting NFIB and KLF3 to suppress the PI3K/AKT signaling pathway

The liver plays a critical role in metabolic activity and is the body's first immune barrier, and maintaining liver health is particularly important for poultry production. MicroRNAs (miRNAs) are involved in a wide range of biological activities due to their capacity as posttranscriptional regulatory elements. A growing body of research indicates that miR-21-5p plays a vital role as a modulator of liver metabolism in various species. However, the effect of miR-21-5p on the chicken liver is unclear. In the current study, we discovered that the fatty liver had high levels of miR-21-5p. Then the qPCR, Western blot, flow cytometry, enzyme-linked immunosorbent assay, dual-luciferase, and immunofluorescence assays were, respectively, used to determine the impact of miR-21-5p in the chicken liver, and it turned out that miR-21-5p enhanced lipogenesis, oxidative stress, and inflammatory responses, which ultimately induced hepatocyte apoptosis. Mechanically, we verified that miR-21-5p can directly target nuclear factor I B (NFIB) and kruppel-like factor 3 (KLF3). Furthermore, our experiments revealed that the suppression of NFIB promoted apoptosis and inflammation, and the KLF3 inhibitor accelerated lipogenesis and enhanced oxidative stress. Furthermore, the cotransfection results suggest that the PI3K/AKT pathway is also involved in the process of miRNA-21-5p-mediate liver metabolism regulation. In summary, our study demonstrated that miRNA-21-5p plays a role in hepatocyte lipogenesis, oxidative stress, inflammation, and apoptosis, via targeting NFIB and KLF3 to suppress the PI3K/AKT signal pathway in chicken.

The role of microRNA-21 (miR-21) in pathogenesis, diagnosis, and prognosis of gastrointestinal cancers: A review

MicroRNAs (miRNAs) are small non-coding RNAs regulating the expression of several target genes. miRNAs play a significant role in cancer biology, as they can downregulate their corresponding target genes by impeding the translation of mRNA (at the mRNA level) as well as degrading mRNAs by binding to the 3'-untranslated (UTR) regions (at the protein level). miRNAs may be employed as cancer biomarkers. Therefore, miRNAs are widely investigated for early detection of cancers which can lead to improved survival rates and quality of life. This is particularly important in the case of gastrointestinal cancers, where early detection of the disease could substantially impact patients' survival. MicroRNA-21 (miR-21 or miRNA-21) is one of the most frequently researched miRNAs, where it is involved in the pathophysiology of cancer and the downregulation of several tumor suppressor genes. In gastrointestinal cancers, miR-21 regulates phosphatase and tensin homolog (PTEN), programmed cell death 4 (PDCD4), mothers against decapentaplegic homolog 7 (SMAD7), phosphatidylinositol 3-kinase /protein kinase B (PI3K/AKT), matrix metalloproteinases (MMPs), β-catenin, tropomyosin 1, maspin, and ras homolog gene family member B (RHOB). In this review, we investigate the functions of miR-21 in pathogenesis and its applications as a diagnostic and prognostic cancer biomarker in four different gastrointestinal cancers, including colorectal cancer (CRC), pancreatic cancer (PC), gastric cancer (GC), and esophageal cancer (EC).

Downregulation of miR-21 as a promising strategy to overcome drug resistance in cancer

Despite tremendous achievements in the field of targeted cancer therapy, chemotherapy is still the main treatment option, which is challenged by acquired drug resistance. Various microRNAs are involved in developing drug-resistant cells. miR-21 is one of the first identified miRNAs involved in this process. Here, we conducted a literature review to categorize different mechanisms employed by miR-21 to drive drug resistance. miR-21 targets various genes involved in many pathways that can justify chemoresistance. It alters cancer cell metabolism and facilitates adaptation to the new environment. It also enhances drug detoxification in cancerous cells and increases genomic instability. We also summarized various strategies applied for the inhibition of miR-21 in order to reverse cancer drug resistance. These strategies include the delivery of antagomiRs, miRZip knockdown vectors, inhibitory small molecules, CRISPR-Cas9 technology, catalytic nucleic acids, artificial DNA and RNA sponges, and nanostructures like mesoporous silica nanoparticles, dendrimers, and exosomes. Furthermore, current challenges and limitations in targeting miR-21 are discussed in this article. Although huge progress has been made in the downregulation of miR-21 in drug-resistant cancer cells, there are still many challenges to be resolved. More research is still required to find the best strategy and timeline for the downregulation of miR-21 and also the most feasible approach for the delivery of this system into the tumor cells. In conclusion, downregulation of miR-21 would be a promising strategy to reverse chemoresistance, but still, more studies are required to clarify the aforementioned issues.

MiR-205-5p Functions as a Tumor Suppressor in Gastric Cancer Cells through Downregulating FAM84B

MicroRNAs (miRNAs) participate in the formation of multiple diseases, including gastric cancer (GC), through modulating specific targets. Here, we explored the functions and regulatory mechanisms of miR-205-5p in GC. MiR-205-5p levels were detected in GC cells through qRT-PCR. Besides, the role of miR-205-5p in cell proliferation, cell apoptosis, cell cycle, cell invasion, and metastasis was assessed through CCK-8 assay, colony formation, flow cytometry, scratch assay, transwell, and western blot. Moreover, the Starbase website was used to predict the target gene of miR-205-5p, further verified by a dual-luciferase reporter assay. Furthermore, the functional effects of the family with sequence similarity 84 member B (FAM84B) on GC mediated by miR-205-5p upregulation were further investigated. MiR-205-5p expression was decreased in GC cells. Upregulation of miR-205-5p inhibited cell proliferation and metastasis and induced apoptosis and cycle arrest of GC cells. Moreover, FAM84B was predicted and confirmed as a target of miR-205-5p and negatively related to miR-205-5p. Mechanically, FAM84B overexpression partially rescued the functional effects of miR-205-5p upregulation on GC cell progression. This study suggests the potential of miR-205-5p/FAM84B as novel targets for the treatment of GC.

Clinical crosstalk between microRNAs and gastric cancer (Review)

Globally, there were over 1 million new gastric cancer (GC) patients in 2018 and GC has become the sixth most common cancer worldwide. GC caused 783,000 deaths worldwide in 2018, making it the third most deadly cancer type. miRNAs are short (~22 nucleotides in length) non‑coding RNA molecules, which can regulate gene expression passively at a post‑transcriptional level. There are more and more in‑depth studies on miRNAs. There are numerous conclusive evidences that there is an inseparable link between miRNAs and GC. miRNAs can affect the entire process of GC, including the oncogenesis, development, diagnosis, treatment and prognosis of GC. Although many miRNAs have been linked to GC, few can be applied to clinical practice. This review takes the clinical changes of GC as a clue and summarizes the miRNAs related to GC that have confirmed the mechanism of action in the past three years. Through in‑depth study and understanding of the mechanism of those miRNAs, we predict their possible clinical uses, and suggest some new insights to overcome GC.

Prediction of MiR-21-5p in Promoting the Development of Lung Adenocarcinoma via PDZD2 Regulation

BACKGROUND Lung adenocarcinoma currently accounts for the highest cancer-related mortality rate worldwide. MiR-21-5p has a vital role in various types of cancers. We have analyzed the miR-21-5p expression level, prognosis, and associated molecular pathways in lung adenocarcinoma with multiple bioinformatics databases. MATERIAL AND METHODS The Cancer Genome Atlas (TCGA) database was employed to fetch the miR-21-5p expression profile in multiple tumors. We used the UALCAN platform to assess the differential regulation of the miR-21-5p in healthy tissue and lung adenocarcinoma. Also, the survival prognosis of the miR-21-5p in each stage of lung adenocarcinoma was done by the Kaplan-Meier database. The STARBASE and UALCAN databases were employed to predict the miR-21-5p target genes, and the levels of target genes and their prognostic value were analyzed. RESULTS MiR-21-5p was overexpressed in the majority of human cancers. MiR-21-5p demonstrated escalated expression in the lung adenocarcinoma tissue in contrast to the normal tissue (P<0.05). Poor prognosis was witnessed in the miR-21-5p high expression group as compared to the low expression group (hazard ratio [HR]= 1.59, P<0.05). PDZD2 was predicted as a miR-21-5p potential target. We found a negative correlation between PDZD2 and miR-21-5p (r=-0.255, P<0.05). PDZD2 was downregulated in lung adenocarcinoma (P<0.05). Overexpression of PDZD2 was associated with a better prognosis of survival in lung adenocarcinoma patients (HR=0.45, P<0.05). CONCLUSIONS MiR-21-5p exhibits the potential to act as a biomarker for the survival prognosis of lung adenocarcinoma. It might be responsible for the onset and progression of lung adenocarcinoma through PDZD2 regulation.

The comprehensive upstream transcription and downstream targeting regulation network of miRNAs reveal potential diagnostic roles in gastric cancer

Evidence has shown that miRNAs can be regulated by multiple mechanisms and can participate in tumorigenesis and progression through binding to 3'-UTRs of target mRNAs. The present study identified differentially expressed miRNAs, mRNAs, and TFs by analyzing miRNA-Seq and mRNA-Seq data to construct a TFs/miRNAs/mRNAs regulation network for GC. We found five miRNAs (miR-18a-5p, miR-21-5p, miR-96-5p, miR-182-5p, and miR-196b-5p) that were significantly overexpressed in GC tissues. Clinical analyses indicated that higher miR-21-5p expression was associated with T3 + T4 and stage III + IV. The expression of miR-96-5p, miR-182-5p, and miR-196b-5p were positively correlated with the patients' ages. The five miRNAs had diagnostic efficacy in distinguishing GC from normal tissues. The gene interaction network showed that the five miRNAs were transcriptionally regulated by 11 TFs and negatively regulated 53 mRNA expressions through binding to the 3'-UTRs. Biological pathway analysis suggested that these TFs and target genes were involved in the p53 pathway, epithelial-to-mesenchymal transition, ErbB receptor, mTOR, VEGF, and VEGFR signaling networks. KEGG pathway analysis indicated that these genes were enriched in some cancer-associated pathways, including in GC. The five miRNAs may act as potential diagnostic markers and the TFs/miRNAs/mRNAs network could suggest a regulation mechanism of miRNAs.

MicroRNA-21-5p targeting PDCD4 suppresses apoptosis via regulating the PI3K/AKT/FOXO1 signaling pathway in tongue squamous cell carcinoma

The aim of the present study was to analyze the role of microRNA (miRNA)-21-5p in tongue squamous cell carcinoma (TSCC), predict the target gene of miR-21-5p and provide novel strategies for gene therapy in TSCC treatment. The expression levels of miRNA-21-5p in TSCC tissues were analyzed using reverse transcription quantitative polymerase chain reaction, and the effects of miRNA-21-5p on cell proliferation, invasion and apoptosis and the expression levels of target protein PDCD4 in the Cal 27 and SCC9 cell lines were determined. PI3K/AKT/Forkhead Box O1 (FOXO1) pathway-associated protein expression levels were evaluated by western blot analysis. miRNA-21-5p was consistently upregulated in TSCC tissues compared with normal tissues. Inhibition of miR-21-5p inhibited cell proliferation and invasion, and promoted cell apoptosis. A luciferase reporter assay confirmed that PDCD4 was the target of miR-21-5p. Inhibition of miRNA21-5p suppressed the PI3K/Akt/FOXO1 signaling pathway. The results from the present study indicated that miR-21-5p-targeting PDCD4 suppresses apoptosis in human TSCC cell lines. This anti-apoptotic effect was achieved by regulating the PI3K/Akt/FOXO1 signaling pathway. These data represent the basis for a promising novel strategy for the treatment of TSCC.

Aberrant MicroRNA Expression and Its Implications for Uveal Melanoma Metastasis

Uveal melanoma (UM) is the most frequently found primary intra-ocular tumor in adults. It is a highly aggressive cancer that causes metastasis-related mortality in up to half of the patients. Many independent studies have reported somatic genetic changes associated with high metastatic risk, such as monosomy of chromosome 3 and mutations in BAP1. Still, the mechanisms that drive metastatic spread are largely unknown. This study aimed to elucidate the potential role of microRNAs in the metastasis of UM. Using a next-generation sequencing approach in 26 UM samples we identified thirteen differentially expressed microRNAs between high-risk UM and low/intermediate-risk UM, including the known oncomirs microRNA-17-5p, microRNA-21-5p, and miR-151a-3p. Integration of the differentially expressed microRNAs with expression data of predicted target genes revealed 106 genes likely to be affected by aberrant microRNA expression. These genes were involved in pathways such as cell cycle regulation, EGF signaling and EIF2 signaling. Our findings demonstrate that aberrant microRNA expression in UM may affect the expression of genes in a variety of cancer-related pathways. This implies that some microRNAs can be responsible for UM metastasis and are promising potential targets for future treatment.

Transcription factor KLF4 modulates microRNA-106a that targets Smad7 in gastric cancer

Mounting evidence has revealed that microRNAs (miRNAs, miRNA) play oncogenic or anti-oncogenic roles in many cancer types. Our previous studies have found the ectopic expression of miR-106a in gastric cancer. However, its deregulation and some potential targets have not yet been fully explored. In this investigation, we identified that the upstream transcriptional factor krüppel-like factor 4 (KLF4), a novel regulator, directly bound to the promoter sequence of miR-106a and was responsible for its deregulation. Using real-time PCR and immunohistochemistry, we further verified that the expression level of KLF4 was negatively correlated with the miR-106a expression in tissue samples. Moreover, the downstream locus was also screened and small mothers against decapentaplegic 7 (Smad7) was revealed to be a direct target of miR-106a, with its 3'-UTR region complementarily bound to miR-106a and the protein expression was mediated by miR-106a in gastric cancer cells, which was confirmed by luciferase assay and Western blot. The role of KLF4-miR-106a-Smad7 in gastric cancer invasion was assessed by real-time PCR and transwell assay. The promoting effect of miR-106a on gastric cancer invasion was significantly abolished by the overexpression of KLF4. The silencing of Smad7 partially promoted the cell invasion when miR-106a was suppressed. In conclusion, we suggest that the ectopic expression of miR-106a is modulated by the upstream transcriptional factor KLF4, which influences the invasive ability of gastric cancer through the downstream target Smad7. MiR-106a should, therefore, be considered as a potential molecular phenotype in gastric cancer.

Clinical significance of miR-195 in hepatocellular carcinoma and its biological function in tumor progression

Background

Hepatocellular carcinoma (HCC) is one of the most lethal cancer types all over the world. Chronic viral hepatitis B and hepatitis C are risk factors that are associated with the development of HCC. The aim of this study is to identify the diagnostic role of serum miR-195 in HCC.

Patients and methods

The expression levels of miR-195 were detected in 120 HCC patients, 64 hepatitis only patients, and 118 healthy control as well as 4 HCC cell lines, by using quantitative real-time PCR. The association of miR-195 with clinicopathological parameters of patients was analyzed with the chi-squared test. The receiver operating characteristic (ROC) curve was adopted to estimate the potential diagnostic value of miR-195. The cell experiments were carried out to verify the functional role of miR-195.

Results

The expression of miR-195 was downregulated in HCC cells and serum of patients compared to the controls (all P<0.05). The miR-195 expression was associated with lymph node metastasis and TNM stage. The ROC curve analysis showed that miR-195 may be a noninvasive diagnostic marker for patients. By using miR-195 mimic or inhibitor, cell proliferation, migration, and invasion were inhibited by miR-195 overexpression but promoted by reduced expression of miR-195.

Conclusion

The downregulation of miR-195 may serve as a novel diagnostic biomarker for differentiating HCC patients, healthy individuals, and hepatitis patients, and may involve in the tumor progression of HCC.