MiR-21/RASA1 axis affects malignancy of colon cancer cells via RAS pathways

Novel insights on perils and promises of miRNA in understanding colon cancer metastasis and progression

Colorectal cancer (CRC) is the third highest frequent malignancy and ultimate critical source of cancer-associated mortality around the world. Regardless of latest advances in molecular and surgical targeted medicines that have increased remedial effects in CRC patients, the 5-year mortality rate for CRC patients remains dismally low. Evidence suggests that microRNAs (miRNAs) execute an essential part in the development and spread of CRC. The miRNAs are a type of short non-coding RNA that exhibited to control the appearance of tumor suppressor genes and oncogenes. miRNA expression profiling is already being utilized in clinical practice as analytical and prognostic biomarkers to evaluate cancer patients' tumor genesis, advancement, and counteraction to drugs. By modulating their target genes, dysregulated miRNAs are linked to malignant characteristics (e.g., improved proliferative and invasive capabilities, cell cycle aberration, evasion of apoptosis, and promotion of angiogenesis). This review presents an updated summary of circulatory miRNAs, tumor-suppressive and oncogenic miRNAs, and the potential reasons for dysregulated miRNAs in CRC. Further we will explore the critical role of miRNAs in CRC drug resistance.

Network embedding framework for driver gene discovery by combining functional and structural information

Comprehensive analysis of multiple data sets can identify potential driver genes for various cancers. In recent years, driver gene discovery based on massive mutation data and gene interaction networks has attracted increasing attention, but there is still a need to explore combining functional and structural information of genes in protein interaction networks to identify driver genes. Therefore, we propose a network embedding framework combining functional and structural information to identify driver genes. Firstly, we combine the mutation data and gene interaction networks to construct mutation integration network using network propagation algorithm. Secondly, the struc2vec model is used for extracting gene features from the mutation integration network, which contains both gene's functional and structural information. Finally, machine learning algorithms are utilized to identify the driver genes. Compared with the previous four excellent methods, our method can find gene pairs that are distant from each other through structural similarities and has better performance in identifying driver genes for 12 cancers in the cancer genome atlas. At the same time, we also conduct a comparative analysis of three gene interaction networks, three gene standard sets, and five machine learning algorithms. Our framework provides a new perspective for feature selection to identify novel driver genes.

miR-21 Targets ASPP2 to Inhibit Apoptosis via CHOP-Mediated Signaling in Helicobacter pylori-Infected Gastric Cancer Cells

Helicobacter pylori (H. pylori) infection affects cell survival pathways, including apoptosis and proliferation in host cells, and disruption of this balance is the key event in the development of H. pylori-induced gastric cancer (HPGC). H. pylori infection induces alterations in microRNAs expression that may be involved in GC development. Bioinformatic analysis showed that microRNA-21 (miR-21) is significantly upregulated in HPGC. Furthermore, quantitative proteomics and in silico prediction were employed to identify potential targets of miR-21. Following functional enrichment and clustered interaction network analyses, five candidates of miR-21 targets, PDCD4, ASPP2, DAXX, PIK3R1, and MAP3K1, were found across three functional clusters in association with cell death and survival, cellular movement, and cellular growth and proliferation. ASPP2 is inhibited by H. pylori-induced miR-21 overexpression. Moreover, ASPP2 levels are inversely correlated with miR-21 levels in HPGC tumor tissues. Thus, ASPP2 was identified as a miR-21 target in HPGC. Here, we observed that H. pylori-induced ASPP2 suppression enhances resistance to apoptosis in GC cells using apoptosis assays. Using protein interaction network and coimmunoprecipitation assay, we identified CHOP as a direct mediator of the ASPP2 proapoptotic activity in H. pylori-infected GC cells. Mechanistically, ASPP2 suppression promotes p300-mediated CHOP degradation, in turn inhibiting CHOP-mediated transcription of Noxa, Bak, and suppression of Bcl-2 to enact antiapoptosis in the GC cells after H. pylori infection. Clinicopathological analysis revealed correlations between decreased ASPP2 expression and higher HPGC risk and poor prognosis. In summary, the discovery of H. pylori-induced antiapoptosis via miR-21-mediated suppression of ASPP2/CHOP-mediated signaling provides a novel perspective for developing HPGC management and treatment.

Molecular Profile of Canine Hemangiosarcoma and Potential Novel Therapeutic Targets

Canine hemangiosarcoma (HSA) is a relatively common neoplasia, occurring mainly in the skin, spleen, liver and right atrium. Despite the numerous studies investigating the treatment of canine HSA, no significant improvement in survival has been achieved in the last 20 years. Advancements in genetic and molecular profiling presented molecular similarities between canine HSA and human angiosarcoma. It could therefore serve as a valuable model for investigating new and more effective treatments in people and dogs. The most common genetic abnormalities in canine HSA have been found in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and neuroblastoma RAS viral oncogene homolog (NRAS) pathways. Mutations are also found in tumor protein p53 (TP53), phosphatase and tensin homolog (PTEN) and cyclin dependent kinase inhibitor 2A (CDKN2A). Known abnormal protein expression could be exploited to trial new target treatments that could be beneficial for both canine and human patients. Despite the high expression of vascular endothelial growth factor (VEGF) and its receptor (VEGFR), no correlation with overall survival time has ever been found. In this review, we explore the most recent developments in molecular profiling in canine HSA and discuss their possible applications in the prognosis and treatment of this fatal disease.

Possible Mechanism of Dysphania ambrosioides (L.) Mosyakin & Clemants Seed Extract Suppresses the Migration and Invasion of Human Hepatocellular Carcinoma Cells SMMC-7721

Mexican tea (Dysphania ambrosioides (L.) Mosyakin & Clemants) is rich in phenolic acids and flavonoids and could be a potential medicinal herb that can be used for prevention of human hepatocellular carcinoma. The objective of this study was to elaborate the possible mechanism for the prevention or treatment of hepatocellular carcinoma using Mexican tea, and to provide new avenues for the utilization of the invasive plant. In this study, the D. ambrosioides seed extracts (CSE) were analyzed by gas chromatography-mass spectrometry, and the effects of CSE on proliferation, migration, invasion, and gene expression of SMMC-7721 cells were investigated. Eight compounds were identified in CSE, and the compound with the highest content was ascaridole (25.82 %). The proliferation was significantly inhibited by CSE (p<0.05), and IC50 values were 0.587 g/L, 0.360 g/L, and 0.361 g/L at 24 h, 36 h, and 48 h, respectively. Migration and invasion were significantly inhibited (p<0.05). The network pharmacology and transcriptome analysis indicated that 2-hydroxy-2,6,6-trimethylbicyclo[3.1.1]heptan-3-one, cis-11-eicosenoic acid and 2-ethylcyclohexanone might be the active compounds. Transcriptome analysis indicated that the Wnt signaling pathway, which is related to migration and invasion, was significantly altered; this was verified by western blot assay. The expression of wnt11, lef1 and mmp7 genes in SMMC-7721 cells was significantly down-regulated (p<0.05), while gsk-3β was significantly up-regulated (p<0.05). These results indicate that CSE inhibits the invasion and migration of SMMC-7721 cells in hepatocellular carcinoma through the Wnt signaling pathway.

Ras superfamily GTPase activating proteins in cancer: Potential therapeutic targets?

To search more therapeutic strategies for Ras-mutant tumors, regulators of the Ras superfamily involved in the GTP/GDP (guanosine triphosphate/guanosine diphosphate) cycle have been well concerned for their anti-tumor potentials. GTPase activating proteins (GAPs) provide the catalytic group necessary for the hydrolysis of GTPs, which accelerate the switch by cycling between GTP-bound active and GDP-bound inactive forms. Inactivated GAPs lose their function in activating GTPase, leading to the continuous activation of downstream signaling pathways, uncontrolled cell proliferation, and eventually carcinogenesis. A growing number of evidence has shown the close link between GAPs and human tumors, and as a result, GAPs are believed as potential anti-tumor targets. The present review mainly summarizes the critically important role of GAPs in human tumors by introducing the classification, function and regulatory mechanism. Moreover, we comprehensively describe the relationship between dysregulated GAPs and the certain type of tumor. Finally, the current status, research progress, and clinical value of GAPs as therapeutic targets are also discussed, as well as the challenges and future direction in the cancer therapy.

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.

Disease progression role as well as the diagnostic and prognostic value of microRNA-21 in patients with cervical cancer: A systematic review and meta-analysis

Introduction

Cervical cancer is the fourth commonest and the fourth leading cause of cancer death in females globally. The upregulated expression of microRNA-21 in cervical cancer has been investigated in numerous studies, yet given the inconsistency on some of the findings, a systematic review and meta-analysis is needed. Therefore, the aim of this systematic review and meta-analysis is to investigate the role in disease progression as well as the diagnostic and prognostic value of microRNA-21 in patients with cervical cancer.

Methods

Literature search was carried out through visiting several electronic databases including PubMed/MEDLINE/ PubMed Central, Web of Science, Embase, WorldCat, DOAJ, ScienceDirect, and Google Scholar. After extraction, data analysis was carried out using Rev-Man 5.3, STATA 15.0 and Meta-disk 1.4. I2 and meta-bias statistics assessed heterogeneity and publication bias of the included studies, respectively. The area under summary receiver operating characteristic curve and other diagnostic indexes were used to estimate diagnostic accuracy.

Result

A total of 53 studies were included for this systematic review and meta-analysis. This study summarized that microRNA-21 targets the expression of numerous genes that regulate their subsequent downstream signaling pathways which promote cervical carcinogenesis. The targets addressed in this study included TNF-α, CCL20, PTEN RasA1, TIMP3, PDCD-4, TPM-1, FASL, BTG-2, GAS-5, and VHL. In addition, the meta-analysis of reports from 6 eligible studies has demonstrated that the overall area under the curve (AUC) of summary receiver operating characteristic (SROC) of microRNA-21 as a diagnostic accuracy index for cervical cancer was 0.80 (95% CI: 0.75, 0.86). In addition, evidence from studies revealed that upregulated microRNA-21 led to worsening progression and poor prognosis in cervical cancer patients.

Conclusion

microRNA-21 is an oncogenic microRNA molecule playing a key role in the development and progression of cervical malignancy. It has good diagnostic accuracy in the diagnosis of cervical cancer. In addition, the upregulation of microRNA-21 could predict a worse outcome in terms of prognosis in cervical cancer patients.

MicroRNAs influence and longevity

Background

MiRNAs play critical roles in the regulation of cellular function, life span, and the aging process. They can affect longevity positively and negatively through different aging pathways.

Main text

MiRNAs are a group of short non-coding RNAs that regulate gene expressions at post-transcriptional levels. The different types of alterations in miRNAs biogenesis, mRNA expressions, and activities of miRNA-protein complexes can affect the regulation of normal post-transcriptional gene process, which may lead to aging, age-related diseases, and an earlier death. It seems that the influence of deregulation of miRNAs on senescence and age-related diseases occurring by targeting aging molecular pathways can be used for diagnosis and prognosis of them. Therefore, the expression and function of miRNAs should be studied more accurately with new applicable and validated experimental tools. However, the current review wishes to highlight simply a connection among miRNAs, senescence and some age-related diseases.

Conclusion

Despite several research indicating the key roles of miRNAs in aging and longevity, further investigations are still needed to elucidate the essential roles of miRNAs in controlling mRNA regulation, cell proliferation, death and/or protection during stress and health problems. Besides, more research on miRNAs will help to identify new targets for alternative strategies regarding effectively screen, treat, and prevent diseases as well as make slow the aging process.

Effects of Multi-Omics Characteristics on Identification of Driver Genes Using Machine Learning Algorithms

Cancer is a complex disease caused by genomic and epigenetic alterations; hence, identifying meaningful cancer drivers is an important and challenging task. Most studies have detected cancer drivers with mutated traits, while few studies consider multiple omics characteristics as important factors. In this study, we present a framework to analyze the effects of multi-omics characteristics on the identification of driver genes. We utilize four machine learning algorithms within this framework to detect cancer driver genes in pan-cancer data, including 75 characteristics among 19,636 genes. The 75 features are divided into four types and analyzed using Kullback–Leibler divergence based on CGC genes and non-CGC genes. We detect cancer driver genes in two different ways. One is to detect driver genes from a single feature type, while the other is from the top N features. The first analysis denotes that the mutational features are the best characteristics. The second analysis reveals that the top 45 features are the most effective feature combinations and superior to the mutational features. The top 45 features not only contain mutational features but also three other types of features. Therefore, our study extends the detection of cancer driver genes and provides a more comprehensive understanding of cancer mechanisms.

Interplay between K-RAS and miRNAs

K-RAS is frequently mutated in cancers, and its overactivation can lead to oncogene-induced senescence (OIS), a barrier to cellular transformation. Feedback onto K-RAS limits its signaling to avoid senescence while achieving the appropriate level of activation that promotes proliferation and survival. Such regulation could be mediated by miRNAs, as aberrant RAS signaling and miRNA activity coexist in several cancers, with miRNAs acting both up- and downstream of K-RAS. Several miRNAs both regulate and are regulated by K-RAS, suggesting a noncoding RNA-based feedback mechanism. Functional interactions between K-RAS and the miRNA machinery have also begun to unfold. This review comprehensively surveys the state of knowledge connecting K-RAS to miRNA function and proposes a model for the regulation of K-RAS signaling by noncoding RNAs.

The Clinical Significance of miR-21 in Guiding Chemotherapy for Patients with Osteosarcoma

Objective

The present study aims to explore the correlation between osteosarcoma (OS) chemosensitivity and the expression levels of serum and tumor tissue micro-ribonucleic acid-21 (miR-21).

Methods

The relevant miR-21 expression levels in 30 patients with OS were detected, and the gender, age, tumor location, pathological type, Enneking stage, and miR-21 expression changes before and after chemotherapy were retrospectively analyzed.

Results

Serum and tumor tissue miR21 expression levels were significantly higher in patients with OS than in control subjects; the serum miR-21 expressions before and after chemotherapy were not related to patient age and gender. The effective chemotherapy group showed significant differences in miR-21 expression levels before and after chemotherapy.

Conclusion

Serum and tumor tissue miR-21 expression levels in patients with OS are closely related to the effects of chemotherapy, making miR-21 a potential biomarker and therapeutic target for the diagnosis and evaluation of chemotherapy effects on patients with OS.

The role of microRNA-21 in the onset and progression of cancer

MicroRNAs (miRNAs), a class of small noncoding RNA, posttranscriptionally regulate the expression of genes. Aberrant expression of miRNA is reported in various types of cancer. Since the first report of oncomiR-21 involvement in the glioma, its upregulation was reported in multiple cancers and was allied with high oncogenic property. In addition to the downregulation of tumor suppressor genes, the miR-21 is also associated with cancer resistance to various chemotherapy. The recent research is appraising miR-21 as a promising cancer target and biomarker for early cancer detection. In this review, we briefly explain the biogenesis and regulation of miR-21 in cancer cells. Additionally, the review features the assorted genes/pathways regulated by the miR-21 in various cancer and cancer stem cells.

Down-regulated placental miR-21 contributes to preeclampsia through targeting RASA1

Human placenta was obtained from early onset preeclampsia, late onset preeclampsia, and their gestational age-matched normal pregnancy. Using RT-qPCR, western blot, and immunohistochemistry, it was demonstrated that miR-21 expressions were significantly decreased in preeclampsia while RASA1 were increased. Suppression of miR-21 in placental HTR-8/SVneo cells, remarkably upregulated RASA1, decreased proliferation, inhibited invasion, and promoted apoptosis of trophoblast cells, while overexpression of miR-21 alleviated these effects. Dual-luciferase reporter assays revealed RASA1 to be a direct target of miR-21 in trophoblast cells. miR-21 may serve key roles in the development of preeclampsia by targeting RASA1.

CircMTO1 inhibits ox-LDL-stimulated vascular smooth muscle cell proliferation and migration via regulating the miR-182-5p/RASA1 axis

Background

Circular RNAs (circRNAs) play critical roles in the development of atherosclerosis (AS). This study investigated the role of circMTO1 in the progression of AS.

Methods

Serum samples from AS patients and healthy volunteers and vascular smooth muscle cells (VSMCs) were used as the study materials. The expressions of circMTO1 and miR-182-5p were measured by RT-qPCR. The effects of circMTO1, miR-182-5p, and RASA1 on VSMC proliferation and apoptosis were examined by MTT and BrdU assays and wound healing and flow cytometric analyses, respectively. Downstream target genes of circMTO1 and miR-182-5p were predicted using target gene prediction and screening and confirmed using a luciferase reporter assay. RASA1 expression was detected by RT-qPCR and Western blot.

Results

circMTO1 expression was decreased, while miR-182-5p expression was increased in human AS sera and oxidized low-density lipoprotein (ox-LDL)-stimulated VSMCs. CircMTO1 overexpression inhibited the proliferation and promoted the apoptosis of ox-LDL-stimulated VSMCs. CircMTO1 was found to be served as a sponge of miR-182-5p and RASA1 as a target of miR-182-5p. Moreover, circMTO1 acted as a ceRNA of miR-182-5p to enhance RASA1 expression. Furthermore, miR-182-5p overexpression and RASA1 knockdown reversed the effects of circMTO1 overexpression on the proliferation, migration, and apoptosis of ox-LDL-stimulated VSMCs.

Conclusion

CircMTO1 inhibited the proliferation and promoted the apoptosis of ox-LDL-stimulated VSMCs by regulating miR-182-5p/RASA1 axis. These results suggest that circMTO1 has potential in AS treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00330-2.

miR-21: A Key Small Molecule with Great Effects in Combination Cancer Therapy

The increasing incidence of various cancers indicates the urgent need for finding accurate early diagnostic markers and more effective treatments for these malignancies. MicroRNAs (miRNAs) are small noncoding RNAs with great potentials to enter into cancer clinics as both diagnostic markers and therapeutic targets. miR-21 is elevated in many cancers, and promotes cell proliferation, metastasis, and drug resistance. In recent years, many studies have shown that targeting miR-21 combined with conventional chemotherapeutic agents could enhance their therapeutic efficacy, and overcome drug resistance and cancer recurrence both in vitro and in animal models. In this review, we first summarize the effects and importance of miR-21 in various cancers, and explore its function in drug resistance of cancer cells. Next, the challenges and prospects for clinical translation of anti-miR-21, as a therapeutic agent, will be discussed in combination cancer therapy.

miR-188-5p promotes oxaliplatin resistance by targeting RASA1 in colon cancer cells

The efficacy of chemotherapy for colon cancer is limited due to the development of chemoresistance. MicroRNA (miR)-188-5p is downregulated in various types of cancer. The aim of the present study was to explore the molecular role of miR-188 in oxaliplatin (OXA) resistance. An OXA-resistant colon cancer cell line, SW480/OXA, was used to examine the effects of miR-188-5p on the sensitivity of colon cancer cells to OXA. The target of miR-188-5p was identified using a luciferase assay. Cell cycle distribution was also assessed using flow cytometry. The measurement of p21 protein expression, Hoechst 33342 staining and Annexin V/propidium iodide staining was used to evaluate apoptosis. The expression of miR-188-5p significantly increased in SW480/OXA compared with wild-type SW480 cells. The luciferase assay demonstrated that miR-188-5p inhibited Ras GTPase-activating protein 1 (RASA1; also known as p120/RasGAP) luciferase activity by binding to the 3'-untranslated region of RASA1 mRNA, suggesting that miR-188-5p could target RASA1. In addition, miR-188-5p downregulation or RASA1 overexpression promoted the chemosensitivity of SW480/OXA, as evidenced by increased apoptosis and G₁/S cell cycle arrest. Moreover, RASA1 silencing abrogated the increase in cell apoptosis induced by the miR-188-5p inhibitor. The findings of the present study suggested that miR-188-5p could enhance colon cancer cell chemosensitivity by promoting the expression of RASA1.

Knockdown of Microtubule Associated Serine/threonine Kinase Like Expression Inhibits Gastric Cancer Cell Growth and Induces Apoptosis by Activation of ERK1/2 and Inactivation of NF-κB Signaling

Microtubule-associated serine/threonine kinase (MASTL) functions to regulate chromosome condensation and mitotic progression. Therefore, aberrant MASTL expression is commonly implicated in various human cancers. This study analyzed MASTL expression in gastric cancer vs. adjacent normal tissue for elucidating the association with clinicopathological data from patients. This work was then extended to investigate the effects of MASTL knockdown on tumor cells in vitro. The level of MASTL expression in gastric cancer tissue was assessed from the UALCAN, GEPIA, and Oncomine online databases. Lentivirus carrying MASTL or negative control shRNA was infected into gastric cancer cells. RT-qPCR, Western blotting, cell viability, cell counting, flow cytometric apoptosis and cell cycle, and colony formation assays were performed. MASTL was upregulated in gastric cancer tissue compared to the adjacent normal tissue, and the MASTL expression was associated with advanced tumor stage, Helicobacter pylori infection and histological subtypes. On the other hand, knockdown of MASTL expression significantly reduced tumor cell viability and proliferation, and arrested cell cycle at G₂/M stage but promoted tumor cells to undergo apoptosis. At protein level, knockdown of MASTL expression enhanced levels of cleaved PARP1, cleaved caspase-3, Bax and p-ERK1/2 expression, but downregulated expression levels of BCL-2 and p-NF-κB-p65 protein in AGS and MGC-803 cells. MASTL overexpression in gastric cancer tissue may be associated with gastric cancer development and progression, whereas knockdown of MASTL expression reduces tumor cell proliferation and induces apoptosis. Further study will evaluate MASTL as a potential target of gastric cancer therapeutic strategy.

Cutting the Brakes on Ras-Cytoplasmic GAPs as Targets of Inactivation in Cancer

Simple Summary

GTPase-Activating Proteins (RasGAPs) are a group of structurally related proteins with a fundamental role in controlling the activity of Ras in normal and cancer cells. In particular, loss of function of RasGAPs may contribute to aberrant Ras activation in cancer. Here we review the multiple molecular mechanisms and factors that are involved in downregulating RasGAPs expression and functions in cancer. Additionally, we discuss how extracellular stimuli from the tumor microenvironment can control RasGAPs expression and activity in cancer cells and stromal cells, indirectly affecting Ras activation, with implications for cancer development and progression.

Abstract

The Ras pathway is frequently deregulated in cancer, actively contributing to tumor development and progression. Oncogenic activation of the Ras pathway is commonly due to point mutation of one of the three Ras genes, which occurs in almost one third of human cancers. In the absence of Ras mutation, the pathway is frequently activated by alternative means, including the loss of function of Ras inhibitors. Among Ras inhibitors, the GTPase-Activating Proteins (RasGAPs) are major players, given their ability to modulate multiple cancer-related pathways. In fact, most RasGAPs also have a multi-domain structure that allows them to act as scaffold or adaptor proteins, affecting additional oncogenic cascades. In cancer cells, various mechanisms can cause the loss of function of Ras inhibitors; here, we review the available evidence of RasGAP inactivation in cancer, with a specific focus on the mechanisms. We also consider extracellular inputs that can affect RasGAP levels and functions, implicating that specific conditions in the tumor microenvironment can foster or counteract Ras signaling through negative or positive modulation of RasGAPs. A better understanding of these conditions might have relevant clinical repercussions, since treatments to restore or enhance the function of RasGAPs in cancer would help circumvent the intrinsic difficulty of directly targeting the Ras protein.

Role of RASA1 in cancer: A review and update (Review)

Ras p21 protein activator 1 (RASA1) is a regulator of Ras GDP and GTP and is involved in numerous physiological processes such as angiogenesis, cell proliferation, and apoptosis. As a result, RASA1 also contributes to pathological processes in vascular diseases and tumour formation. This review focuses on the role of RASA1 in multiple tumours types in the lung, intestines, liver, and breast. Furthermore, we discuss the potential mechanisms of RASA1 and its downstream effects through Ras/RAF/MEK/ERK or Ras/PI3K/AKT signalling. Moreover, miRNAs are capable of regulating RASA1 and could be a novel targeted treatment strategy for tumours.

miR‑31 promotes tumorigenesis in ulcerative colitis‑associated neoplasia via downregulation of SATB2

Ulcerative colitis (UC) features chronic, non-infectious inflammation of the colon. The risk of ulcerative colitis‑associated neoplasia (UCAN) increases in direct association with the duration of this disease. Whether miRNAs exert a regulatory effect on the pathogenesis of UCAN has remained to be elucidated. In the present study, differentially expressed genes (DEGs) and microRNAs (miRNAs/miRs) were identified using bioinformatics analysis of Gene Expression Omnibus datasets. Enrichment analyses were performed to determine the function of the DEGs. The target genes of key miRNAs were predicted using miRWalk. Validation of DEGs and miRNAs in patients with UC, UC with low‑grade dysplasia and UC with high‑grade dysplasia (UC‑HGD) was performed using reverse transcription‑quantitative PCR analysis. A total of 38 differentially expressed miRNAs and 307 mRNAs were identified from the profiles and miR‑31 was validated as being overexpressed in UCAN tissues, particularly in the UC‑HGD samples. Furthermore, special AT‑rich DNA‑binding protein 2 (SATB2) was validated as a target gene of miR‑31 and SATB2 expression was negatively correlated with miR‑31 expression. Therefore, miR‑31 is upregulated in UCAN and it may promote tumorigenesis through downregulation of SATB2.

Genome-wide investigation of gene-cancer associations for the prediction of novel therapeutic targets in oncology

A major cause of failed drug discovery programs is suboptimal target selection, resulting in the development of drug candidates that are potent inhibitors, but ineffective at treating the disease. In the genomics era, the availability of large biomedical datasets with genome-wide readouts has the potential to transform target selection and validation. In this study we investigate how computational intelligence methods can be applied to predict novel therapeutic targets in oncology. We compared different machine learning classifiers applied to the task of drug target classification for nine different human cancer types. For each cancer type, a set of “known” target genes was obtained and equally-sized sets of “non-targets” were sampled multiple times from the human protein-coding genes. Models were trained on mutation, gene expression (TCGA), and gene essentiality (DepMap) data. In addition, we generated a numerical embedding of the interaction network of protein-coding genes using deep network representation learning and included the results in the modeling. We assessed feature importance using a random forests classifier and performed feature selection based on measuring permutation importance against a null distribution. Our best models achieved good generalization performance based on the AUROC metric. With the best model for each cancer type, we ran predictions on more than 15,000 protein-coding genes to identify potential novel targets. Our results indicate that this approach may be useful to inform early stages of the drug discovery pipeline.

Inhibition of miR-21 Regulates Mutant KRAS Effector Pathways and Intercepts Pancreatic Ductal Adenocarcinoma Development

Almost all pancreatic ductal adenocarcinomas (PDA) develop following KRAS activation, which triggers epithelial transformation and recruitment of desmoplastic stroma through additional transcriptional and epigenetic regulation, but only a few of these regulatory mechanisms have been described. We profiled dysregulated miRNAs starting with the earliest premalignant pancreatic intraepithelial neoplasias (PanIN) in genetically engineered mutated KRAS and P53 (KPC) mice programmed to recapitulate human PDA tumorigenesis. We identified miR-21 and miR-224 as cell-specific and compartment-specific regulators in PanINs and PDA. miR-21 is overexpressed in tumor epithelial cells of premalignant ducts, while miR-224 is overexpressed in cancer-associated fibroblasts in PDA stroma. Inhibition of miR-21 reverted protumorigenic functionalities to baseline levels. Overexpression of miR-224 induced activated phenotypes in normal fibroblasts. In vivo miR-21 inhibition improved survival in established PDA. Importantly, early systemic miR-21 inhibition completely intercepted premalignant progression. Finally, an evaluation of miR-21 expression in the PDA cohort of The Cancer Genome Atlas identified a correlation between tumor epithelial cell content and miR-21 expression in human tumors providing further rationale for conducting human studies. Thus, miR-21 may be useful for early PanIN detection, and for intercepting developing premalignant pancreatic lesions and other KRAS-driven premalignancies.

microRNAs targeting cellular cholesterol: implications for combating anticancer drug resistance

Over sixty percent of all mammalian protein-coding genes are estimated to be regulated by microRNAs (miRNAs), and unsurprisingly miRNA dysregulation has been linked with cancer. Aberrant miRNA expression in cancer cells has been linked with tumourigenesis and drug resistance. In the past decade, increasing number of studies have demonstrated that cholesterol accumulation fuels tumour growth and contributes to drug resistance, therefore, miRNAs controlling cholesterol metabolism and homeostasis are obvious hypothetical targets for investigating their role in cholesterol-mediated drug resistance in cancer. In this review, we have collated published evidences to consolidate this hypothesis and have scrutinized it by utilizing computational tools to explore the role of miRNAs in cholesterol-mediated drug resistance in breast cancer cells. We found that hsa-miR-128 and hsa-miR-223 regulate genes mediating lipid signalling and cholesterol metabolism, cancer drug resistance and breast cancer genes. The analysis demonstrates that targeting these miRNAs in cancer cells presents an opportunity for developing new strategies to combat anticancer drug resistance.

The potential role of regulatory microRNAs of RAS/MAPK signaling pathway in the pathogenesis of colorectal cancer

Colorectal cancer (CRC) is the leading cause of cancer death worldwide. Dysregulation of RAS/MAPK signaling axis is frequently found in CRC patients. The RAS/MAPK axis regulates cancer cell proliferation, apoptosis, inflammation, migration, and metastasis. Oncogenic or tumor-suppressor microRNAs (miRNAs) for RAS/MAPK signaling play a key role in the pathogenesis of CRC and are considered as novel potential biomarkers for diagnosis and prognosis of human malignancies. This review summarizes the current knowledge of mechanisms of action of RAS/MAPK miRNAs in the development and progression of CRC for a better understanding and hence a better management of this disease.

MicroRNA‑4530 suppresses cell proliferation and induces apoptosis by targeting RASA1 in human umbilical vein endothelial cells

MicroRNAs (miRNAs/miRs) are a class of endogenous and non-coding RNAs that are present in eukaryotes. In previous studies, miRNAs have been revealed to have an important role in cell growth and apoptosis. In the present study, the function of a novel and rarely studied miRNA, miR-4530, was investigated in human umbilical vein endothelial cells (HUVECs). The expression level of miR-4530 in HUVECs was investigated using reverse transcription-quantitative polymerase chain reaction following transfection with miR-4530 precursor plasmids, anti-miR-4530 plasmids and empty vector plasmids. Following this, it was revealed that overexpression of miR-4530 can suppress cell proliferation and enhance cell apoptosis. TargetScan analysis suggested that Ras p21 protein activator 1 (RASA1) is a target gene of miR-4530. The results of a dual-luciferase reporter assay also suggested that miR-4530 targets RASA1. Furthermore, the results of dual-luciferase reporter assay suggested that miR-4530 enhanced luciferase activity of the wild-type reporter, but not the mutant RASA1 reporter activity, thus suggesting that miR-4530 enhances the expression of RASA1. In addition, western blot analysis demonstrated that the protein expression level of RASA1 was enhanced following upregulation of miR-4530. The exact mechanism underlying this process has not yet been determined and requires further investigation. In addition, a RASA1 overexpression plasmid vector was transfected into HUVECs. The results suggest that overexpression of RASA1 suppresses cell growth and promotes apoptosis, which was in agreement with the results regarding the overexpression of miR-4530. To investigate how miRNA-4530 affects cellular function, numerous proteins associated with the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT serine/threonine kinase pathways were investigated via western blot analysis. The results suggested that miRNA-4530 suppresses cell proliferation and enhances apoptosis by targeting RASA1 via the ERK/MAPK and PI3K/AKT signaling pathways.

CRISPR-induced RASGAP deficiencies in colorectal cancer organoids reveal that only loss of NF1 promotes resistance to EGFR inhibition

Anti-EGFR therapy is used to treat metastatic colorectal cancer (CRC) patients, for which initial response rates of 10-20% have been achieved. Although the presence of HER2 amplifications and oncogenic mutations in KRAS, NRAS, and BRAF are associated with EGFR-targeted therapy resistance, for a large population of CRC patients the underlying mechanism of RAS-MEK-ERK hyperactivation is not clear. Loss-of-function mutations in RASGAPs are often speculated in literature to promote CRC growth as being negative regulators of RAS, but direct experimental evidence is lacking. We generated a CRISPR-mediated knock out panel of all RASGAPs in patient-derived CRC organoids and found that only loss of NF1, but no other RASGAPs e.g. RASA1, results in enhanced RAS-ERK signal amplification and improved tolerance towards limited EGF stimulation. Our data suggests that NF1-deficient CRCs are likely not responsive to anti-EGFR monotherapy and can potentially function as a biomarker for CRC progression.

MiRNA as biomarker for uveitis - A systematic review of the literature

AIM

A systematic review of miRNA profiling studies in uveitis.

METHODS

Literature search strategy - Pubmed central central database, using miRNA/microRNA and intraocular inflammation/uveitis as keywords.

RESULTS

We found twenty publications regarding the experimental and clinical use of miRNA in uveitis, published between 2011 and 2018.

CONCLUSION

The publications regarding the role of miRNA in uveitis are very scarce, but provide some valuable information about the potential new mechanisms in uveitis. Some of the identified miRNAs in different uveitis entities could serve as a biomarker of intraocular inflammation. Possible candidate miRNAs could be let-7e, miRNA-1, miR-9-3, miR-20a-5p, miR-23a, mir-29a-3p, miR-140-5p, miR-143, miR-146a and miR-146a-5p, miR-155, miR-182 and miR-182-5p, miR-196a2, miR-205, miR-223-3p, miR-301a. MiR-146a, miR-146a-5p, miR-155, miR-182, miR-223-3p, have been found to be possibly associated with uveitis disease in both, human and animal species.

MicroRNA-21 and its impact on signaling pathways in cervical cancer

Oncogenic microRNA-21 (miR-21/miRNA-21) is a stable inhibitor of gene expression that is often upregulated in cervical cancer, a disease that affects the health of women and tends to transform and spread. Previous studies investigating miR-21 in biopsies and cells from cervical cancer patients have identified that miR-21 binds target mRNAs in signaling pathways or long non-coding RNAs (lncRNA). Furthermore, studies have elucidated the molecular mechanisms of two tumor necrosis factor α (TNF-α) signaling pathways that promote cell proliferation and inhibit cell apoptosis. miR-21 inhibits the TNF receptor 1 (TNFR1) signaling pathway and activates the TNFR2 signaling pathway. Moreover, miR-21 enhances cervical cancer cell proliferation by influencing the protein kinase B/mammalian target of rapamycin and RAS p21 protein activator 1 signaling pathways. The present review discusses the evidence that miR-21 may impact cervical cancer through inhibiting apoptosis and enhancing proliferation, and may therefore be a target for clinical intervention.

Proteomic profiling reveals key cancer progression modulators in shed microvesicles released from isogenic human primary and metastatic colorectal cancer cell lines

Extracellular vesicles comprise two main classes - exosomes and shed microvesicles (sMVs). Whilst much is known about exosome cargo content and functionality, sMVs are poorly understood. Here, we describe the large-scale purification of sMVs released from primary (SW480) and metastatic (SW620) human isogenic colorectal cancer (CRC) cell lines using a combination of differential ultracentrifugation and isopycnic iodixanol density centrifugation. The yield of SW480-sMVs and SW620-sMVs was 0.75 mg and 0.80 mg, respectively. Both SW480-/SW620-sMVs are heterogeneous in size (100-600 nm diameter) and exhibit identical buoyant densities (1.10 g/mL). In contrast to exosomes, sMVs are ALIX^-, TSG101^-, CD63^- and CD9^-. Quantitative mass spectrometry identified 1295 and 1300 proteins in SW480-sMVs and SW620-sMVs, respectively. Gene Ontology enrichment analysis identified 'cell adhesion' (CDH1, OCLN, CTN families), 'signalling pathway' (KRAS, NRAS, MAPK1, MAP2K1), and 'translation/RNA related' processes (EIF, RPL, HNRNP families) in both sMV types. Strikingly, SW480- and SW620-sMVs exhibit distinct protein signatures - SW480-sMVs being enriched in ITGA/B, ANXA1, CLDN7, CD44 and EGFR/NOTCH signalling networks, while SW620-sMVs are enriched in PRKCA, MACC1, FGFR4 and MTOR/MARCKS signalling networks. Both SW480- and SW620-sMVs are taken up by NIH3T3 fibroblasts resulting in similar cell invasion capability. This study provides, for the first time, molecular insights into sMVs and CRC biology.

miR-130b-5p promotes proliferation, migration and invasion of gastric cancer cells via targeting RASAL1

The aim of the present study was to investigate the targeted interaction between microRNA (miR)-130b-5p and RAS protein activator like 1 (RASAL1) gene and elucidate the function of miR-130b-5p in cell proliferation, migration and invasion in gastric cancer. Expression of miR-130b-5p and RASAL1 in seven gastric cell lines was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). MGC803 cells were selected for further study since they exhibited a marked increase in expression of miR-130b-5p accompanied by decreased expression of RASAL1. MGC803 cells were transfected with miR-130b-5p mimics and miR-130b-5p inhibitor using Lipofectamine 2000 for over- and underexpression, respectively, with cells transfected with negative control (NC) sequence as the control. In addition, a luciferase reporter gene assay was performed to evaluate the targeted interaction between miR-130b-5p and RASAL1. Then, alterations in RASAL1 expression were detected by RT-qPCR and western blot analysis following transfection with miR-130b-5p mimics and miR-130b-5p inhibitor. Cell proliferation, colony formation, and migration and invasion ability were detected by MTT, colony formation and Transwell assays, respectively. RASAL1 was demonstrated to be a target gene of miR-130b-5p by luciferase reporter gene assay. In addition, the expression of RASAL1 was significantly lower in MGC803 cells that were transfected with miR-130b-5p mimics and significantly higher in cells transfected with miR-130b-5p inhibitor in comparison with cells transfected with NC (P<0.05). Furthermore, the experimental group transfected with miR-130b-5p mimics manifested significantly higher cell proliferation, increased colony formation and increased migratory and invasive capacities (P<0.05). By contrast, cells transfected with miR-130b-5p inhibitor exhibited significantly lower cell proliferation, decreased colony formation and decreased migratory and invasive capacities, compared with cells transfected with NC (P<0.05). In conclusion, RASAL1 was demonstrated to be a target gene of miR-130b-5p. Overexpression of miR-130b-5p results in promoted proliferation, colony formation and migration and invasion abilities through targeted modulation of RASAL1.

KRAS induces lung tumorigenesis through microRNAs modulation

Oncogenic KRAS induces tumor onset and development by modulating gene expression via different molecular mechanisms. MicroRNAs (miRNAs) are small non-coding RNAs that have been established as main players in tumorigenesis. By overexpressing wild type or mutant KRAS (KRASG12D) and using inducible human and mouse cell lines, we analyzed KRAS-regulated microRNAs in non-small-cell lung cancer (NSCLC). We show that miR-30c and miR-21 are significantly upregulated by both KRAS isoforms and induce drug resistance and enhance cell migration/invasion via inhibiting crucial tumor suppressor genes, such as NF1, RASA1, BID, and RASSF8. MiR-30c and miR-21 levels were significantly elevated in tumors from patients that underwent surgical resection of early stages NSCLC compared to normal lung and in plasma from the same patients. Systemic delivery of LNA-anti-miR-21 in combination with cisplatin in vivo completely suppressed the development of lung tumors in a mouse model of lung cancer. Mechanistically, we demonstrated that ELK1 is responsible for miR-30c and miR-21 transcriptional activation by direct binding to the miRNA proximal promoter regions. In summary, our study defines that miR-30c and miR-21 may be valid biomarkers for early NSCLC detection and their silencing could be beneficial for therapeutic applications.

Weighted gene co-expression network analysis reveals potential genes involved in early metamorphosis process in sea cucumber Apostichopus japonicus

Sea cucumbers, one main class of Echinoderms, have a very fast and drastic metamorphosis process during their development. However, the molecular basis under this process remains largely unknown. Here we systematically examined the gene expression profiles of Japanese common sea cucumber (Apostichopus japonicus) for the first time by RNA sequencing across 16 developmental time points from fertilized egg to juvenile stage. Based on the weighted gene co-expression network analysis (WGCNA), we identified 21 modules. Among them, MEdarkmagenta was highly expressed and correlated with the early metamorphosis process from late auricularia to doliolaria larva. Furthermore, gene enrichment and differentially expressed gene analysis identified several genes in the module that may play key roles in the metamorphosis process. Our results not only provide a molecular basis for experimentally studying the development and morphological complexity of sea cucumber, but also lay a foundation for improving its emergence rate.

Circulating MicroRNA-21 Is Involved in Lymph Node Metastasis in Cervical Cancer by Targeting RASA1

OBJECTIVE

The aims of this study were to discover if increased circulating microRNA-21 (miR-21) expression in serum is associated with lymph node metastasis in patients with cervical cancer and look further into the molecular mechanism of these. Whole-blood samples from 89 patients who have been histopathologically confirmed as having cervical cancer and 20 control subjects were collected, and then the association between lymph node metastasis and the level of circulating miR-21 was compared. Then cervical cancer cell lines HeLa (HPV-18 DNA, E6/E7RNA) and HT-3 (HPV DNA, E6/E7RNA) were used to confirm the interaction between miR-21 and RASA1. The role of RASA1 in cervical cancer cell migration was also studied in HeLa. Increased circulating miR-21 expression in serum is associated with lymph node metastasis in patients with cervical cancer. MicroRNA-21 reduces RASA1 expression in cervical cancer cell lines and promotes cervical cancer cell migration via RASA1. Furthermore, Ras-induced epithelial-mesenchymal transition contributes to miR-21/RASA1 axis promoting cervical cancer cell migration. Circulating miR-21 in serum could be a promising biomarker in auxiliary diagnosis of lymph node metastasis in cervical cancer, and inhibition of miR-21/RASA1 axis could be a possible strategy to restrain migration of cervical cancer.

Co-expression and significance of Dok2 and Ras p21 protein activator 1 in breast cancer

Docking protein 2 (Dok2) and Ras p21 protein activator 1 (RASA1) are tumor suppressors which have been identified in numerous solid tumors; however, the association between their expression in breast cancer and patient prognosis remains unclear. A total of 285 consecutive patients diagnosed histopathologically with breast cancer who underwent surgery at Jingzhou Central Hospital were selected for the present study. Dok2 and RASA1 protein were explored using histopathology and western blotting techniques, and the association of patient prognosis with clinicopathological parameters was investigated using univariate and multivariate analyses. Weak expression of Dok2/RASA1 was associated with poorly differentiated breast adenocarcinomas; negatively expressed Dok2 and RASA1 were associated with increased tumor size, a higher proportion of axillary lymph node metastasis and later clinical staging. Additionally, Dok2 and RASA1 expression were associated with disease-free survival of patients with breast cancer. As indicated by Cox's regression analysis, Dok2 and RASA1 expression and the high proportion of axillary lymph node metastasis served as significant independent predictors for the recurrence of breast cancer. The results of the present study suggested that combined Dok2 and RASA1 negative expression may serve as an independent prognostic factor for patients following breast cancer surgery.

Potential roles of microRNAs and ROS in colorectal cancer: diagnostic biomarkers and therapeutic targets

As one of the most commonly diagnosed cancers worldwide, colorectal adenocarcinoma often occurs sporadically in individuals aged 50 or above and there is an increase among younger patients under 50. Routine screenings are recommended for this age group to improve early detection. The multifactorial etiology of colorectal cancer consists of both genetic and epigenetic factors. Recently, studies have shown that the development and progression of colorectal cancer can be attributed to aberrant expression of microRNA. Reactive oxygen species (ROS) that play a key role in cancer cell survival, can also lead to carcinogenesis and cancer exacerbations. Given the rapid accumulating knowledge in the field, an updated review regarding microRNA and ROS in colorectal cancer is necessary. An extensive literature search has been conducted in PubMed/Medline databases to review the roles of microRNAs and ROS in colorectal cancer. Unique microRNA expression in tumor tissue, peripheral blood, and fecal samples from patients with colorectal cancer is outlined. Therapeutic approaches focusing on microRNA and ROS in colorectal cancer treatment is also delineated. This review aims to summarize the newest knowledge on the pathogenesis of colorectal cancer in the hopes of discovering novel diagnostic biomarkers and therapeutic techniques.

Current Status and Perspectives Regarding LNA-Anti-miR Oligonucleotides and microRNA miR-21 Inhibitors as a Potential Therapeutic Option in Treatment of Colorectal Cancer

Colorectal cancer (CRC) is among the leading causes of cancer-related death, principally due to its metastatic spread and multifactorial chemoresistance. The therapeutic failure can also be explained by inter- or intra-tumor genetic heterogeneity and tumor stromal content. Thus, the identification of novel prognostic biomarkers and therapeutic options are warranted in the management of CRC patients. There are data showing that microRNA-21 is elevated in different types of cancer, particularly colon adenocarcinoma and that this is association with a poor prognosis. This suggests that microRNA-21 may be of value as a potential therapeutic target. Furthermore, locked nucleic acid (LNA)-modified oligonucleotides have recently emerged as a therapeutic option for targeting dysregulated miRNAs in cancer therapy, through antisense-based gene silencing. Further work is required to identify innovative anticancer drugs that improve the current therapy either through novel combinatorial approaches or with better efficacy than conventional drugs. We aimed to provide an overview of the preclinical and clinical studies targeting key dysregulated signaling pathways in CRC as well as the therapeutic application of LNA-modified oligonucleotides, and miR inhibitors in the treatment of CRC patients. J. Cell. Biochem. 118: 4129-4140, 2017. © 2017 Wiley Periodicals, Inc.

Inhibition of microRNA-21 via locked nucleic acid-anti-miR suppressed metastatic features of colorectal cancer cells through modulation of programmed cell death 4

Colorectal cancer is among the most lethal of malignancies, due to its propensity to metastatic spread and multifactorial-chemoresistance. The latter property supports the need to identify novel therapeutic approaches for the treatment of colorectal cancer. MicroRNAs are endogenous non-coding small RNA molecules that function as post-transcriptional regulators of gene expression. Recently, programmed cell death 4 has been identified as a protein that increases during apoptosis. This gene is among the potential targets of miR-21 (OncomiR). Locked nucleic acid-modified oligonucleotides have recently emerged as a potential therapeutic option for targeting microRNAs. The aim of this study was to explore the functional role of locked nucleic acid-anti-miR-21 in the LS174T cell line in vitro and in vivo models. LS174T cells were treated with locked nucleic acid-anti-miR-21 for 24, 48, and 72 h in vitro. The expression of miR-21 and PDCD4 at messenger RNA (mRNA) level was evaluated by quantitative real-time polymerase chain reaction, while the protein level of PDCD4 was determined by Western blotting. Cell migratory behavior and the cluster-forming ability of cells were assessed before and after therapy. The disseminated tumor cells were assessed in the chick chorioallantoic membrane model by Alu quantitative polymerase chain reaction. Locked nucleic acid-anti-miR-21 was transfected successfully into the LS174T cells and inhibited the expression of miR-21. Locked nucleic acid-anti-miR-21 inhibited the migration and the number of cells forming clusters. Moreover, we found that locked nucleic acid-anti-miR-21 transfection was associated with a significant reduction in metastatic properties as assessed by the in ovo model. Our findings demonstrated the novel therapeutic potential of locked nucleic acid-anti-miR-21 in colon adenocarcinoma with high miR-21 expression.

Argonaute 2 immunoprecipitation revealed large tumor suppressor kinase 1 as a novel proapoptotic target of miR-21 in T cells

MicroRNA (miR)-21 is an important suppressor of T-cell apoptosis that is also overexpressed in many types of cancers. The exact mechanisms underlying the antiapoptotic effects of miR-21 are not well understood. In this study, we used the Jurkat T-cell line as a model to identify apoptosis-associated miR-21 target genes. We showed that expression of miR-21 rapidly increases upon αCD3/αCD28 activation of Jurkat cells. Inhibition of miR-21 reduced cell growth which could be explained by an increase in apoptosis. MicroRNA target gene identification by AGO2 RNA-immunoprecipitation followed by gene expression microarray (RIP-Chip) resulted in the identification of 72 predicted miR-21 target genes that were at least twofold enriched in the AGO2-IP fraction of miR-21 overexpressing cells. Of these, 71 were at least twofold more enriched in the AGO2-IP fraction of miR-21 overexpressing cells as compared to AGO2-IP fraction of control cells. The target gene for which the AGO2-IP enrichment was most prominently increased upon miR-21 overexpression was the proapoptotic protein LATS1. Luciferase reporter assays and western blot analysis confirmed targeting of LATS1 by miR-21. qRT-PCR analysis in primary T cells showed an inverse expression pattern between LATS1 transcript levels and miR-21 upon T-cell stimulation. Finally, LATS1 knockdown partially rescued the miR-21 inhibition-induced impaired cell growth. Collectively, these data identify LATS1 as a miR-21 target important for the antiapoptotic function of miR-21 in T cells and likely also in many types of cancer.

Circulating exosomes and exosomal microRNAs as biomarkers in gastrointestinal cancer. Cancer Gene Ther. 2017;24:48-56. [PMID: 27982021 DOI: 10.1038/cgt.2016.77]

The most important biological function of exosomes is their possible use as biomarkers in clinical diagnosis. Compared with biomarkers identified in conventional specimens such as serum or urine, exosomal biomarkers provide the highest amount of sensitivity and specificity, which can be attributed to their excellent stability. Exosomes, which harbor different types of proteins, nucleic acids and lipids, are present in almost all bodily fluids. The molecular constituents of exosomes, especially exosomal proteins and microRNAs (miRNAs), are promising as biomarkers in clinical diagnosis. This discovery that exosomes also contain messenger RNAs and miRNAs shows that they could be carriers of genetic information. Although the majority of RNAs found in exosomes are degraded RNA fragments with a length of <200 nucleotides, some full-length RNAs might be present that may affect protein production in the recipient cell. In addition, exosomal miRNAs have been found to be associated with certain diseases. Several studies have pointed out miRNA contents of circulating exosomes that are similar to those of originating cancer cells. In this review, the recent advances in circulating exosomal miRNAs as biomarkers in gastrointestinal cancers are discussed. These studies indicated that miRNAs can be detected in exosomes isolated from body fluids such as saliva, which suggests potential advantages of using exosomal miRNAs as noninvasive novel biomarkers.

A miRNAs panel promotes the proliferation and invasion of colorectal cancer cells by targeting GABBR1

MicroRNAs (miRNAs) have been implicated in the regulation of colorectal cancer. Despite the expression of miR-17-92 cluster in cancer has been gradually revealed, the role of each individual miRNAs in colorectal cancer still remains unclear. We studied the impact of miR-106a/b, miR-20a/b, and miR-17 of miR-17-92 cluster on colorectal cancer cells. Real-time quantitative polymerase chain reactions (RT-PCR) were used to test these five miRNAs expression in colorectal cancer cell line HCT116. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assays, Bromodeoxyuridine (BrdU), and Transwell invasion assays were used to explore the effects of these five miRNAs in colorectal cancer cells. Luciferase reporter assay, RT-PCR, and western blotting were performed to validate the interaction of these five miRNAs with the gamma-amino-butyric acid type B receptor 1(GABBR1). We found that these five miRNAs were significantly upregulated in colorectal cancer samples compared with normal tissues. Forced expression of these five miRNAs significantly promoted HCT116 and HT-29 cells proliferation and invasion. We further found that these five miRNAs function as oncogenes in colorectal cancer by specifically binding to the 3-untranslated regions (3'UTR) of GABBR1.Furthermore, inhibition of GABBR1 could mimic the function of miRNAs in HCT116 cells, while overexpression of GABBR1 blocked the function of miRNAs-promoted proliferation and invasion. In conclusion, miR-106a/b, miR-20a/b, and miR-17 contribute to the proliferation and invasion of colorectal cancer by targeting their common target gene, GABBR1, and played a critical role in the proliferation and invasion of colorectal cancer.

Locked nucleic acid anti-miR-21 inhibits cell growth and invasive behaviors of a colorectal adenocarcinoma cell line: LNA-anti-miR as a novel approach

Colorectal cancer (CRC) is the third leading cause of cancer-related death and has an extremely poor prognosis. Dysregulation of microRNAs (miRNAs) has been shown to be involved in the pathogenesis and progression of many malignancies. Recent data suggest that microRNA-21 (miR-21) is significantly elevated in different types of cancer, especially colon adenocarcinoma. Against this background, locked nucleic acid (LNA)-modified oligonucleotides have recently been suggested as a novel approach for targeting miRNAs as antisense-based gene silencing. The aim of the current study was to explore the functional role of LNA-anti-miR-21 in a colon adenocarcinoma LS174T cell line. LS174T cells were transfected with LNA-anti-miR-21 for 24, 48 and 72 h. Quantitative real-time reverse transcriptase-PCR (qRT-PCR) was performed to assess miR-21 expression by LNA-anti-miR-21. The viability of the cells was evaluated by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) assay and Annexin V/propidium iodide staining assay was used to detect apoptosis. Moreover, invasive behavior of the cells was evaluated before and after therapy by transwell assay. LNA-anti-miR-21 was successfully transfected in human LS174T cells and suppressed the endogenous miR-21. LNA-anti-miR-21 inhibited the cells' growth followed by induction of apoptosis. LNA-anti-miR-21 (50 pmol/μl) reduced the invasive behaviors of LS174T cells after 24 h, compared with untreated cells and scrambled LNA-transfected cells. However, this effect was more pronounced after 72 h. Our findings suggest the therapeutic potential of LNA-anti-miR-21 in a colon adenocarcinoma for targeting miR-21 expression. Further studies are warranted to investigate the molecular mechanisms underlying this novel inhibitor in colorectal cancer to establish its potential value for treatment of CRC patients with high miR-21 expression.

Triptolide reduces proliferation and enhances apoptosis of human non-small cell lung cancer cells through PTEN by targeting miR-21

Triptolide is used in traditional Chinese medicine. It has the advantages of a unique mechanism of action, a wide antitumor spectrum, multiple targets, multi-channel effects and low toxicity. The current study was conducted to evaluate whether the potential anticancer effects of triptolide reduces proliferation and enhances apoptosis of human non‑small cell lung cancer (NSCLC) cells, and to assess the underlying anticancer mechanisms. In PC‑9 cells, treatment with triptolide reduced cell proliferation and increased cell apoptosis and caspase‑3 and 9 activity. Triptolide treatment reduced miR‑21 expression and enhanced phosphatase and tensin homolog (PTEN) protein expression levels in the PC‑9 cells. Furthermore, the upregulation of miR‑21 expression levels suppressed the effect of triptolide on cell viability and PTEN protein expression levels in PC‑9 cells. To the best of our knowledge, the present study is the first to demonstrate that triptolide reduced the proliferation and enhanced the apoptosis of human NSCLC cells through PTEN by targeting miR-21.

Noncoding RNAs and pancreatic cancer

Noncoding RNAs (ncRNAs) represent a class of RNA molecules that typically do not code for proteins. Emerging data suggest that ncRNAs play an important role in several physiological and pathological conditions such as cancer. The best-characterized ncRNAs are the microRNAs (miRNAs), which are short, approximately 22-nucleotide sequences of RNA of approximately 22-nucleotide in length that regulate gene expression at the posttranscriptional level, through transcript degradation or translational repression. MiRNAs can function as master gene regulators, impacting a variety of cellular pathways important to normal cellular functions as well as cancer development and progression. In addition to miRNAs, long ncRNAs, which are transcripts longer than 200 nucleotides, have recently emerged as novel drivers of tumorigenesis. However, the molecular mechanisms of their regulation and function, and the significance of other ncRNAs such as piwi-interacting RNAs in pancreas carcinogenesis are largely unknown. This review summarizes the growing body of evidence supporting the vital roles of ncRNAs in pancreatic cancer, focusing on their dysregulation through both genetic and epigenetic mechanisms, and highlighting the promise of ncRNAs in diagnostic and therapeutic applications of pancreatic cancer.

Transcriptional Regulation of miR-31 by Oncogenic KRAS Mediates Metastatic Phenotypes by Repressing RASA1

Activating KRAS mutations are nearly ubiquitous in pancreatic cancer occurring in more than 95% of clinical cases. miRNAs are small noncoding RNAs that regulate gene expression by binding sequences within the 3'UTRs of target mRNAs. An integral role for miRNAs in cancer pathogenesis is well established; however, the role of miRNAs in KRAS-mediated tumorigenesis is poorly characterized. Here it is demonstrated that expression of miR-31 is coupled to the expression of oncogenic KRAS and activity of the MAPK pathway. miR-31 is highly expressed in patient-derived xenografts and a panel of pancreatic and colorectal cancer cells harboring activating KRAS mutations. The miR-31 host gene is a large noncoding RNA that correlates with miR-31 expression and enabled identification of the putative miR-31 promoter. Using luciferase reporters, a minimal RAS-responsive miR-31 promoter was found to drive robust luciferase activity dependent on expression of mutant KRAS and the transcription factor ELK1. Furthermore, ELK1 interacts directly with the endogenous miR-31 promoter in a MAPK-dependent manner. Expression of enforced miR-31 significantly enhanced invasion and migration of multiple pancreatic cancer cells resulting from the activation of RhoA through regulation of the miR-31 target gene RASA1. Importantly, acute knockdown of RASA1 phenocopied enforced miR-31 expression on the migratory behavior of pancreatic cancer cells through increased RhoA activation.

IMPLICATIONS

Oncogenic KRAS can activate Rho through the miR-31-mediated regulation of RASA1 indicating miR-31 acts as a KRAS effector to modulate invasion and migration in pancreatic cancer.