The miR-18a* microRNA functions as a potential tumor suppressor by targeting on K-Ras

RNA-binding proteins and exoribonucleases modulating miRNA in cancer: the enemy within

Recent progress in the investigation of microRNA (miRNA) biogenesis and the miRNA processing machinery has revealed previously unknown roles of posttranscriptional regulation in gene expression. The molecular mechanistic interplay between miRNAs and their regulatory factors, RNA-binding proteins (RBPs) and exoribonucleases, has been revealed to play a critical role in tumorigenesis. Moreover, recent studies have shown that the proliferation of hepatocellular carcinoma (HCC)-causing hepatitis C virus (HCV) is also characterized by close crosstalk of a multitude of host RBPs and exoribonucleases with miR-122 and its RNA genome, suggesting the importance of the mechanistic interplay among these factors during the proliferation of HCV. This review primarily aims to comprehensively describe the well-established roles and discuss the recently discovered understanding of miRNA regulators, RBPs and exoribonucleases, in relation to various cancers and the proliferation of a representative cancer-causing RNA virus, HCV. These have also opened the door to the emerging potential for treating cancers as well as HCV infection by targeting miRNAs or their respective cellular modulators.

Stratification of acute myocardial and endothelial cell injury, salvage index and final infarct size by systematic microRNA profiling in acute ST-elevation myocardial infarction

AIM

Acute injury and subsequent remodelling responses to ST-segment elevation myocardial infarction (STEMI) are major determinants of clinical outcome. Current imaging and plasma biomarkers provide delayed readouts of myocardial injury and recovery. Here, we sought to systematically characterize all microRNAs (miRs) released during the acute phase of STEMI and relate miR release to magnetic resonance imaging (MRI) findings to predict acute and late responses to STEMI, from a single early blood sample.

METHODS AND RESULTS

miRs were quantified in blood samples obtained from patients after primary PCI (PPCI) for STEMI. Cardiac MRI (cMRI) was performed to quantify myocardial edema, infarct size and salvage index. Regression models were constructed to predict these outcomes measures, which were then tested with a validation cohort. Transcoronary miR release was quantified from paired measurements of coronary artery and coronary sinus samples. A cell culture model was used to identify endothelial cell-derived miRs.A total of 72 patients undergoing PPCI for acute STEMI underwent miR analysis and cMRI. About >200 miRs were detectable in plasma after STEMI, from which 128 miRs were selected for quantification in all patients. Known myocardial miRs demonstrated a linear correlation with troponin release, and these increased across the transcoronary gradient. We identified novel miRs associated with microvascular injury and myocardial salvage. Regression models were constructed using a training cohort, then tested in a validation cohort, and predicted myocardial oedema, infarct size and salvage index.

CONCLUSION

Analysis of miR release after STEMI identifies biomarkers that predict both acute and late outcomes after STEMI. A novel miR-based biomarker score enables the estimation of area at risk, late infarct size and salvage index from a single blood sample 6 hours after PPCI, providing a simple and rapid alternative to serial cMRI characterization of STEMI outcome.

Deciphering the role of KRAS gene in oncogenesis: Focus on signaling pathways, genetic alterations in 3'UTR, KRAS specific miRNAs and therapeutic interventions

Cancer is a significant cause of death after cardiovascular disease. The genomic, epigenetic and environmental factors have been found to be the risk factor for the disease. The most important genes that develop cancer are oncogenes and tumor suppressor genes. Among oncogenes, KRAS has emerged as a significant player in the development of many cancers. Dysregulation of the RAS signaling pathway either on account of mutation in significant genes involved in the pathway or aberrant expression of different miRNAs targeting these genes including KRAS. The focus is also on the alterations in 3'UTR of the KRAS gene sequence as well as the changes in the miRNA encoding genes especially the one targeting the KRAS gene. Efforts are also being put in to target the dysregulated KRAS gene as a therapeutic approach to treat different cancers. However, there are some challenges like resistance to KRAS inhibitors that need to be addressed.

Non-coding RNAs as potential therapeutic targets for receptor tyrosine kinase signaling in solid tumors: current status and future directions

This review article presents an in-depth analysis of the current state of research on receptor tyrosine kinase regulatory non-coding RNAs (RTK-RNAs) in solid tumors. RTK-RNAs belong to a class of non-coding RNAs (nc-RNAs) responsible for regulating the expression and activity of receptor tyrosine kinases (RTKs), which play a critical role in cancer development and progression. The article explores the molecular mechanisms through which RTK-RNAs modulate RTK signaling pathways and highlights recent advancements in the field. This include the identification of potential new RTK-RNAs and development of therapeutic strategies targeting RTK-RNAs. While the review discusses promising results from a variety of studies, encompassing in vitro, in vivo, and clinical investigations, it is important to acknowledge the challenges and limitations associated with targeting RTK-RNAs for therapeutic applications. Further studies involving various cancer cell lines, animal models, and ultimately, patients are necessary to validate the efficacy of targeting RTK-RNAs. The specificity of ncRNAs in targeting cellular pathways grants them tremendous potential, but careful consideration is required to minimize off-target effects, the article additionally discusses the potential clinical applications of RTK-RNAs as biomarkers for cancer diagnosis, prognosis, and treatment. In essence, by providing a comprehensive overview of the current understanding of RTK-RNAs in solid tumors, this review emphasizes their potential as therapeutic targets for cancer while acknowledging the associated challenges and limitations.

From strings to signals: Unraveling the impact of miRNAs on diagnosis, and progression of colorectal cancer

Colorectal cancer (CRC) stands as the third most prevalent ailment globally and represents the primary cause of mortality associated with cancer. Significant advancements have been made in the clinical management of patients with CRC, encompassing the development of more streamlined methodologies and a diverse array of biomarkers utilized for prognostic, diagnostic, and predictive objectives. MicroRNAs (miRNAs, miRs) play a key role in the development of CRC by modulating the expression of their target genes, which govern a number of metabolic and cellular processes. They are related to malignant traits such as enhanced invasive and proliferative capacity, evasion of apoptosis, cell cycle aberration, and promotion of angiogenesis through dysregulation in their function. This review's objectives were to examine miRNA biogenesis, provide an updated list of oncogenic and tumor suppressor miRNAs, and discuss the likely causes of miRNA dysregulation in CRC. Additionally, we discuss the diagnostic and predictive functions of miRNAs in CRC and summarize their biological significance and clinical potential.

Alternative splicing impacts microRNA regulation within coding regions

MicroRNAs (miRNAs) are small non-coding RNA molecules that bind to target sites in different gene regions and regulate post-transcriptional gene expression. Approximately 95% of human multi-exon genes can be spliced alternatively, which enables the production of functionally diverse transcripts and proteins from a single gene. Through alternative splicing, transcripts might lose the exon with the miRNA target site and become unresponsive to miRNA regulation. To check this hypothesis, we studied the role of miRNA target sites in both coding and non-coding regions using six cancer data sets from The Cancer Genome Atlas (TCGA) and Parkinson's disease data from PPMI. First, we predicted miRNA target sites on mRNAs from their sequence using TarPmiR. To check whether alternative splicing interferes with this regulation, we trained linear regression models to predict miRNA expression from transcript expression. Using nested models, we compared the predictive power of transcripts with miRNA target sites in the coding regions to that of transcripts without target sites. Models containing transcripts with target sites perform significantly better. We conclude that alternative splicing does interfere with miRNA regulation by skipping exons with miRNA target sites within the coding region.

Decoding the role of miRNAs in multiple myeloma pathogenesis: A focus on signaling pathways

Multiple myeloma (MM) is a cancer of plasma cells that has been extensively studied in recent years, with researchers increasingly focusing on the role of microRNAs (miRNAs) in regulating gene expression in MM. Several non-coding RNAs have been demonstrated to regulate MM pathogenesis signaling pathways. These pathways might regulate MM development, apoptosis, progression, and therapeutic outcomes. They are Wnt/β-catenin, PI3K/Akt/mTOR, P53 and KRAS. This review highlights the impending role of miRNAs in MM signaling and their relationship with MM therapeutic interventions.

Can Dietary Actives Affect miRNAs and Alter the Course or Prevent Colorectal Cancer?

Colorectal cancer is a diet-related cancer. There is much research into the effects of nutrients on the prevention, modulation, and treatment of colorectal cancer. Researchers are trying to find a correlation between epidemiological observations indicating certain dietary components as the originator in the process of developing colorectal cancer, such as a diet rich in saturated animal fats, and dietary components that could eliminate the impact of harmful elements of the daily nutritional routine, i.e., substances such as polyunsaturated fatty acids, curcumin, or resveratrol. Nevertheless, it is very important to understand the mechanisms underlying how food works on cancer cells. In this case, microRNA (miRNA) seems to be a very significant research target. MiRNAs participate in many biological processes connected to carcinogenesis, progression, and metastasis. However, this is a field with development prospects ahead. In this paper, we review the most significant and well-studied food ingredients and their effects on various miRNAs involved in colorectal cancer.

Significance of miRNAs on the thyroid cancer progression and resistance to treatment with special attention to the role of cross-talk between signaling pathways

Thyroid cancer (TC) is the most prevalent endocrine malignant tumor. It has many types, the Papillary thyroid cancer (PTC)(most common and follicular thyroid carcinoma (FTC). Several risk factors have been associated with TC radiation exposure, autoimmunity, and genetics. Microribonucleic acids (miRNAs) are the most important genetic determinants of TC. They are small chains of nucleic acids that are able to inhibit the expression of several target genes. They could target several genes involved in TC proliferation, angiogenesis, apoptosis, development, and even resistance to therapy. Besides, they could influence the stemness of TC. Moreover, they could regulate several signaling pathways such as WNT/β-catenin, PI3K/AKT/mTOR axis, JAK/STAT, TGF- β, EGFR, and P53. Besides signaling pathways, miRNAs are also involved in the resistance of TC to major treatments such as surgery, thyroid hormone-inhibiting therapy, radioactive iodine, and adjuvant radiation. The stability and sensitivity of several miRNAs might be exploited as an approach for the usage of miRNAs as diagnostic and/or prognostic tools in TC.

One locus, several functional RNAs-emerging roles of the mechanisms responsible for the sequence variability of microRNAs

With the development of modern molecular genetics, the original "one gene-one enzyme" hypothesis has been outdated. For protein coding genes, the discovery of alternative splicing and RNA editing provided the biochemical background for the RNA repertoire of a single locus, which also serves as an important pillar for the enormous protein variability of the genomes. Non-protein coding RNA genes were also revealed to produce several RNA species with distinct functions. The loci of microRNAs (miRNAs), encoding for small endogenous regulatory RNAs, were also found to produce a population of small RNAs, rather than a single defined product. This review aims to present the mechanisms contributing to the astonishing variability of miRNAs revealed by the new sequencing technologies. One important source is the careful balance of arm selection, producing sequentially different 5p- or 3p-miRNAs from the same pre-miRNA, thereby broadening the number of regulated target RNAs and the phenotypic response. In addition, the formation of 5', 3' and polymorphic isomiRs, with variable end and internal sequences also leads to a higher number of targeted sequences, and increases the regulatory output. These miRNA maturation processes, together with other known mechanisms such as RNA editing, further increase the potential outcome of this small RNA pathway. By discussing the subtle mechanisms behind the sequence diversity of miRNAs, this review intends to reveal this engaging aspect of the inherited "RNA world", how it contributes to the almost infinite molecular variability among living organisms, and how this variability can be exploited to treat human diseases.

Use of Personalized Biomarkers in Metastatic Colorectal Cancer and the Impact of AI

Colorectal cancer is a major cause of cancer-related death worldwide and is correlated with genetic and epigenetic alterations in the colonic epithelium. Genetic changes play a major role in the pathophysiology of colorectal cancer through the development of gene mutations, but recent research has shown an important role for epigenetic alterations. In this review, we try to describe the current knowledge about epigenetic alterations, including DNA methylation and histone modifications, as well as the role of non-coding RNAs as epigenetic regulators and the prognostic and predictive biomarkers in metastatic colorectal disease that can allow increases in the effectiveness of treatments. Additionally, the intestinal microbiota’s composition can be an important biomarker for the response to strategies based on the immunotherapy of CRC. The identification of biomarkers in mCRC can be enhanced by developing artificial intelligence programs. We present the actual models that implement AI technology as a bridge connecting ncRNAs with tumors and conducted some experiments to improve the quality of the model used as well as the speed of the model that provides answers to users. In order to carry out this task, we implemented six algorithms: the naive Bayes classifier, the random forest classifier, the decision tree classifier, gradient boosted trees, logistic regression and SVM.

KRAS Promoter Methylation Status and miR-18a-3p and miR-143 Expression in Patients With Wild-type KRAS Gene in Colorectal Cancer

BACKGROUND/AIM

Although some mutations of KRAS proto-oncogene, GTPase (KRAS) have been associated with the prognosis and therapeutic management of colorectal cancer (CRC), the epigenetic mechanisms (DNA methylation and microRNA expression) that regulate wild-type KRAS expression in patients with CRC are poorly known. The aim of this study was to establish whether there is a relationship between the expression of the wild-type KRAS gene, the methylation status of its distal promoter, and miR-143 and miR-18a-3p levels in samples of sporadic CRC.

PATIENTS AND METHODS

A total of 51 cases of sporadic CRC with wild-type KRAS were analyzed. The expression levels of KRAS mRNA, miR-18a-3p, miR-143, and KRAS protein, as well as methylation in the distal promoter of the KRAS gene were evaluated.

RESULTS

In the analyzed cases, KRAS mRNA expression was detected in 51.1%; wild-type KRAS protein was found in the membrane in 31.4% and in the cytoplasm in 98% of cases. An inverse relationship of marginal significance was observed between miR-18a-3p and KRAS protein expression in the cytoplasm (odds ratio=0.14, 95% confidence interval=0.012-1.092; p=0.08). The methylation status of the distal promoter of KRAS at four CpG islands was analyzed in 30 cases (58.8%): partial methylation of the four CpG islands evaluated was observed in two cases (6.7%). In these cases, KRAS protein expression was not evidenced at the membrane level; miR-18a-3p expression was not detected either but high expression of miR-143 was observed.

CONCLUSION

No association was found between the expression levels of KRAS mRNA, miR-18a-3p, miR-143 and methylation status. Methylation status was detected with low frequency, thus being the first report of methylation in wild-type KRAS.

Emerging role of non-coding RNAs in the regulation of KRAS

The Kirsten ras oncogene KRAS is a member of the small GTPase superfamily participating in the RAS/MAPK pathway. A single amino acid substitution in KRAS gene has been shown to activate the encoded protein resulting in cell transformation. This oncogene is involved in the malignant transformation in several tissues. Notably, numerous non-coding RNAs have been found to interact with KRAS protein. Such interaction results in a wide array of human disorders, particularly cancers. Orilnc1, KIMAT1, SLCO4A1-AS1, LINC01420, KRAS1P, YWHAE, PART1, MALAT1, PCAT-1, lncRNA-NUTF2P3-001 and TP53TG1 are long non-coding RNAs (lncRNAs) whose interactions with KRAS have been verified in the context of cancer. miR-143, miR-96, miR-134 and miR-126 have also been shown to interact with KRAS in different tissues. Finally, circITGA7, circ_GLG1, circFNTA and circ-MEMO1 are examples of circular RNAs (circRNAs) that interact with KRAS. In this review, we describe the interaction between KRAS and lncRNAs, miRNAs and circRNAs, particularly in the context of cancer.

Interrelationship between miRNA and splicing factors in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers because of diagnosis at late stage and inherent/acquired chemoresistance. Recent advances in genomic profiling and biology of this disease have not yet been translated to a relevant improvement in terms of disease management and patient’s survival. However, new possibilities for treatment may emerge from studies on key epigenetic factors. Deregulation of microRNA (miRNA) dependent gene expression and mRNA splicing are epigenetic processes that modulate the protein repertoire at the transcriptional level. These processes affect all aspects of PDAC pathogenesis and have great potential to unravel new therapeutic targets and/or biomarkers. Remarkably, several studies showed that they actually interact with each other in influencing PDAC progression. Some splicing factors directly interact with specific miRNAs and either facilitate or inhibit their expression, such as Rbfox2, which cleaves the well-known oncogenic miRNA miR-21. Conversely, miR-15a-5p and miR-25-3p significantly downregulate the splicing factor hnRNPA1 which acts also as a tumour suppressor gene and is involved in processing of miR-18a, which in turn, is a negative regulator of KRAS expression. Therefore, this review describes the interaction between splicing and miRNA, as well as bioinformatic tools to explore the effect of splicing modulation towards miRNA profiles, in order to exploit this interplay for the development of innovative treatments. Targeting aberrant splicing and deregulated miRNA, alone or in combination, may hopefully provide novel therapeutic approaches to fight the complex biology and the common treatment recalcitrance of PDAC.

Portrait of Cancer Stem Cells on Colorectal Cancer: Molecular Biomarkers, Signaling Pathways and miRNAome

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.

A Review of AEG-1 Oncogene Regulating MicroRNA Expression in Colon Cancer Progression

MicroRNAs are a class of small non-coding RNAs that perform a crucial function in posttranscriptional gene regulation. Dysregulation of these microRNAs is associated with many types of cancer progression. In tumorigenesis, downregulated microRNAs might function as a tumour suppressor by repressing oncogenes, whereas overexpressed miRs might function as oncogenes by suppressing tumour suppressor. Similarly, Metadherin (also known as AEG-1/ LYRIC), is an oncogene, the levels of which are found to be very high in various cancers and play a crucial role in the proliferation of cells and invasion. Our review focuses on the study, which shows the alteration of microRNA expression profile and suppression of carcinogenesis when MTDH/AEG-1 is targeted. It summarises the studies where downregulation and upregulation of AEG-1 and microRNAs, respectively, alter the biological functions of the cell, such as proliferation and apoptosis. Studies have reported that AEG-1 can be direct or indirect target of microRNA, which could provide a new-insight to know the underlying molecular mechanism and might contribute to the progress of new therapeutic strategies for the disease.

MicroRNAs: potential biomarkers for diagnosis and prognosis of different cancers

A thorough understanding of the tumor environment and underlying genetic factors helps in the better formulation of cancer management strategies. Availability of efficient diagnostic and prognostic biomarkers facilitates early detection and progression of the disease. MicroRNAs affect different biological processes participating in tumorigenesis through regulation of their target genes. An expanding list of unique RNAs and understanding of their regulatory role has opened up a new field in cancer research. Based on a comprehensive literature search, we identified 728 miRNAs dysregulated in sixteen cancer types namely bladder cancer (BC), breast cancer (BrC), cervical cancer (CC), colorectal cancer (CRC), esophageal cancer (EC), endometrial cancer (EnC), gastric cancer (GC), hepatocellular cancer (HCC), head and neck squamous cell cancer (HNSCC), lung cancer (LC), ovarian cancer (OC), pancreatic cancer (PC), prostate cancer (PrC), renal cell cancer (RCC), skin cancer (SC), and thyroid cancer (TC). Expression of 43 miRNAs was either upregulated or downregulated in six or more of these cancers. Finally, seven miRNAs namely mir-18a, mir-21, mir-143/145, mir-210, mir-218, mir-221, showing maximum dysregulation, either up- or down-regulation in the majority of cancers, were selected for a detailed presentation of their expression and evaluation of their potential as biomarkers in the diagnosis and prognosis of different cancers.

The significance of microRNA deregulation in colorectal cancer development and the clinical uses as a diagnostic and prognostic biomarker and therapeutic agent

Colorectal cancer (CRC) is one of the most widely recognized and deadly malignancies worldwide. Although death rates have declined over the previous decade, mainly because of enhanced screening or potential treatment alternatives, CRC remains the third leading cause of cancer-related mortality globally, with an estimated incidence of over 1 million new cases and approximately 600 000 deaths estimated yearly. Therefore, many scientific efforts are put into the development of new diagnostic biomarkers for CRC. MicroRNAs (miRNAs), one of the epigenetics categories, have demonstrated significant roles in carcinogenesis and progression through regulating epithelial-mesenchymal transition (EMT), oncogenic signaling pathways, and metastasis. Dysregulation of miRNAs expression has been reported in many cancers, including CRC. The expression profile of miRNAs is reproducibly altered in CRC, and their expression patterns are associated with diagnosis, prognosis, and therapeutic outcomes in CRC. Recently, many studies were conducted on the dysregulation of miRNAs as a diagnostic and prognostic biomarker in CRC. Among them, some miRNAs, which include miR-21, miR-34 family, miR-155, miR-224, and miR-378, have been more studied in CRC with more prominent roles in diagnosis, prognosis, and therapy. In the present review, we summarized the latest information regarding the dysregulated miRNAs in CRC and the advantages of using miRNAs as a biomarker for CRC diagnosis, treatment, and their function in different signaling pathways involved in CRC progression. Moreover, we described the translation of miRNA research to potential therapeutic applications in the management of CRC in clinical settings.

Good or not good: Role of miR-18a in cancer biology

miR-18a is a member of primary transcript called miR-17-92a (C13orf25 or MIR17HG) which also contains five other miRNAs: miR-17, miR-19a, miR-20a, miR-19b and miR-92a. This cluster as a whole shows specific characteristics, where miR-18a seems to be unique. In contrast to the other members, the expression of miR-18a is additionally controlled and probably functions as its own internal controller of the cluster. miR-18a regulates many genes involved in proliferation, cell cycle, apoptosis, response to different kinds of stress, autophagy and differentiation. The disturbances of miR-18a expression are observed in cancer as well as in different diseases or pathological states. The miR-17-92a cluster is commonly described as oncogenic and it is known as 'oncomiR-1', but this statement is a simplification because miR-18a can act both as an oncogene and a suppressor. In this review we summarize the current knowledge about miR-18a focusing on its regulation, role in cancer biology and utility as a potential biomarker.

miR-18a Inhibits BMP4 and HIF-1α Normalizing Brain Arteriovenous Malformations

RATIONALE

Brain arteriovenous malformations (AVMs) are abnormal tangles of vessels where arteries and veins directly connect without intervening capillary nets, increasing the risk of intracerebral hemorrhage and stroke. Current treatments are highly invasive and often not feasible. Thus, effective noninvasive treatments are needed. We previously showed that AVM-brain endothelial cells (BECs) secreted higher VEGF (vascular endothelial growth factor) and lower TSP-1 (thrombospondin-1) levels than control BEC; and that microRNA-18a (miR-18a) normalized AVM-BEC function and phenotype, although its mechanism remained unclear.

OBJECTIVE

To elucidate the mechanism of action and potential clinical application of miR-18a as an effective noninvasive treatment to selectively restore the phenotype and functionality of AVM vasculature.

METHODS AND RESULTS

The molecular pathways affected by miR-18a in patient-derived BECs and AVM-BECs were determined by Western blot, RT-qPCR (quantitative reverse transcription polymerase chain reaction), ELISA, co-IP, immunostaining, knockdown and overexpression studies, flow cytometry, and luciferase reporter assays. miR-18a was shown to increase TSP-1 and decrease VEGF by reducing PAI-1 (plasminogen activator inhibitor-1/SERPINE1) levels. Furthermore, miR-18a decreased the expression of BMP4 (bone morphogenetic protein 4) and HIF-1α (hypoxia-inducible factor 1α), blocking the BMP4/ALK (activin-like kinase) 2/ALK1/ALK5 and Notch signaling pathways. As determined by Boyden chamber assays, miR-18a also reduced the abnormal AVM-BEC invasiveness, which correlated with a decrease in MMP2 (matrix metalloproteinase 2), MMP9, and ADAM10 (ADAM metallopeptidase domain 10) levels. In vivo pharmacokinetic studies showed that miR-18a reaches the brain following intravenous and intranasal administration. Intranasal co-delivery of miR-18a and NEO100, a good manufacturing practices-quality form of perillyl alcohol, improved the pharmacokinetic profile of miR-18a in the brain without affecting its pharmacological properties. Ultra-high-resolution computed tomography angiography and immunostaining studies in an Mgp^-/- AVM mouse model showed that miR-18a decreased abnormal cerebral vasculature and restored the functionality of the bone marrow, lungs, spleen, and liver.

CONCLUSIONS

miR-18a may have significant clinical value in preventing, reducing, and potentially reversing AVM.

KRAS-associated microRNAs in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancerrelated death worldwide. Despite progress in treatment of cancers, CRC with KRAS mutations are resistant towards anti-EGFR treatment. MicroRNAs have been discovered in an exponential manner within the last few years and have been known to exert either an onco-miRNA or tumor suppressive effect. Here, the various roles of microRNAs involved in the initiation and progression of KRAS-regulated CRC are summarized. A thorough understanding of the roles and functions of the plethora of microRNAs associated with KRAS in CRC will grant insights into the provision of other potential therapeutic targets as well as treatment. MicroRNAs may also serve as potential molecular classifier or early detection biomarkers for future treatment and diagnosis of CRC.

Effects of Lactobacillus acidophilus and Bifidobacterium bifidum Probiotics on the Expression of MicroRNAs 135b, 26b, 18a and 155, and Their Involving Genes in Mice Colon Cancer

A wide range of sources supports that the link between diet and colorectal cancer may be due to an imbalance of the intestinal microflora. In this case, it seems that the probiotics may have a possible molecular mechanism via microRNAs (miRNAs). The present study is aimed to evaluate the effects of Lactobacillus acidophilus and Bifidobacterium bifidum probiotics on the expression of miRNAs 135b, 26b, 18a, and 155 and their target genes, including APC, PTEN, KRAS, and PU.1 in mouse azoxymethane (AOM)-induced colon cancer. Thirty-eight male BALB/c mice were randomly divided into four groups: the control, AOM, Lactobacillus acidophilus, and Bifidobacterium bifidum to deliberate the effects of the probiotics on the miRNAs and their target genes. Except for the control group, the rest groups were weekly given AOM (15 mg/kg, s.c) in three consecutive weeks to induce mouse colon cancer. The animals were given 1.5 g powders of L. acidophilus (1 × 10⁹ cfu/g) and B. bifidum (1 × 10⁹ cfu/g) in 30 cc drinking water in the related groups for 5 months. At the end of the study, the animals were sacrificed and their blood and colon samples were removed for the molecular analyses. The results showed that the expression of the miR-135b, miR-155, and KRAS was increased in the AOM group compared to the control group in both the plasma and the colon tissue samples, and the consumption of the probiotics decreased their expression. Moreover, the miR-26b, miR-18a, APC, PU.1, and PTEN expressions were decreased in the AOM group compared to the control group and the consumption of the probiotics increased their expressions. It seems that Lactobacillus acidophilus and Bifidobacterium bifidum though increasing the expression of the tumor suppressor miRNAs and their target genes and decreasing the oncogenes can improve colon cancer treatment.

Role of non-coding RNAs as novel biomarkers for detection of colorectal cancer progression through interaction with the cell signaling pathways

Colorectal cancer (CRC) is one of the most common types of cancer which affects the colon and the rectum. Approximately one third of annual CRC mortality occurs due to the late detection of this type of cancer. Therefore, there is an urgent need for more powerful diagnostic and prognostic tools for identification and treatment of colorectal tumorigenesis. Non-coding RNAs (ncRNAs) have been implicated in the pathology of CRC and also linked to metastasis, proliferation, differentiation, migration, angiogenesis and apoptosis in numerous cancers. Recently, attention has turned towards ncRNAs as specific targets for diagnosis, prognosis and treatment of various types of cancers, including CRC. In this review, we have tried to outline the roles of ncRNAs, and their involvement in signaling pathways responsible for the progression of CRC.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Complexity in regulating microRNA biogenesis in cancer

The discovery of microRNA (miRNA) significantly extends our knowledge on gene regulation and noncoding gene functions. MiRNAs are important post-transcriptional regulators involve in a wide range of biological functions and diseases, including cancer. MiRNAs are produced by a unique biogenesis pathway involving the two-step sequential nuclear and cytoplasmic RNase-dependent processing at post-transcriptional level. However, a specific (set) of miRNA(s) is (are) synthesized under certain circumstance or developmental/pathological stage to fine-tune the gene expression profile. In this minireview, we will discuss the mechanism of miRNA biogenesis in cancer, mainly focusing on how Drosha and Dicer, two critical molecules controlling miRNA biogenesis, are modulated and which factor contributes to the specificity of selected miRNA maturation.

Impact statement

The canonical maturation pathway of miRNAs is highly conserved, indicating the crucial roles of these mini-regulators in most cellular processes. Dysregulation of specific miRNAs or imbalance of miRNA abundance has been observed in cancers. Accumulating evidence has shown that the interplay between miRNA processing factors and regulatory proteins previously known as key players in cancer malignancy regulates the biogenesis of miRNAs, expression of target genes, and eventually the alteration of cellular phenotypes. This minireview summarizes the current findings in the modulation of miRNA biogenesis in cancer to advance the understanding of how noncoding RNA contributes to cancer development and malignancy.

The prognostic value of miRNA-18a-5p in clear cell renal cell carcinoma and its function via the miRNA-18a-5p/HIF1A/PVT1 pathway

Purpose Clear cell renal cell carcinoma(ccRCC) is the most common type of renal cell carcinoma. While it is curable when detected at an early stage, some patients presented with advanced disease have poor prognosis. We aimed to identify key genes and miRNAs associated with clinical prognosis in ccRCC.

Methods The microarray datasets were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were analyzed by using GEO2R. Then, Functional enrichment analysis was performed using the DAVID. A retrospective series of 254 ccRCC patients with complete clinical information was included in this study. Kaplan-Meier analysis and multivariate cox regression analysis were used for prognostic analysis. Wound healing assay and transwell assay were designed to evaluate the migration and invasion ability of ccRCC cell lines.

Results miRNA-18a was identified to be related with prognosis of ccRCC by using Kaplan-Meier analysis and multivariate cox regression analysis demonstrated that the prognostic value of miRNA-18a was independent of clinical features. Further studies showed that up-regulation of miRNA-18a had a positive effect on migration and invasion of ccRCC cells. The target gene (HIF1A) of the miRNA-18a was predicted by using the miRPathDB database. The transcription factors of DEGs were identified by using the i-cisTarget. Luckily, HIF1A was found to be one of the transcription factors of DEGs. Among these DEGs, PVT1 may be regulated by HIF1A and be related with prognosis of ccRCC. Finally, validation of miRNA18a/HIF1A/PVT1 pathway was checked via reverse transcription-polymerase chain reaction (RT-PCR) assay in both cell lines and clinical tumor samples.

Conclusion Our research revealed that miRNA18a/HIF1A/PVT1 pathway might play a crucial role in ccRCC progression, providing novel insights into understanding of ccRCC molecular mechanisms. Importantly, miRNA-18a could serve as a potential diagnostic biomarker and therapeutic targets for ccRCC patients.

ADAR1p150 regulates the biosynthesis and function of miRNA-149* in human melanoma

Melanoma is an aggressive malignant skin tumor. Study found that miR-149* was abnormally expressed in melanoma. Adenosine deaminases acting on the RNA1 (ADAR1) is an RNA editing enzyme. It can change the structure and function of miRNA. In this study, we investigate the role of ADAR1 in regulation of miRNA-149* in melanoma. Western-blot analysis was used to analyze the expression of ADAR1p150, ADAR1p110 and GSK3α at protein level. The expression of ADAR1p150, miR-149* and GSK3α at mRNA level were detected using qRT-PCR. Co-immunoprecipitation test was then performed to determine the interaction between ADAR1 and Dicer. Target verification of miRNA-149*/GSK3α was carried out using luciferase reporter assay. CCK-8 was used to detect cell proliferation. Cell apoptosis was tested using Tunel assays. The expression level of ADAR1p150 was found to be increased in human melanoma tissues, but not ADAR1p110. There was a direct interaction between ADAR1p150 and Dicer in melanoma cells. MiRNA-149* was significantly up-regulated in melanoma tissues and melanoma cells. Luciferase reporter assay suggested that GSK3α was a directly target of miR-149*. The expression level of miR-149* showed a positive correlation with ADAR1p150. At the same time, ADAR1p150 expression was negatively correlated with the expression of GSK3α. ADAR1p150 promoted proliferation of melanoma cells and inhibited cell apoptosis. ADAR1p150 can promote the biosynthesis and function of miRNA-149* in melanoma cells which makes it be considered as both a bio-marker and a therapeutic target for treatment of melanoma.

Deregulation of cancer-stem-cell-associated miRNAs in tissues and sera of colorectal cancer patients

Colorectal cancer (CRC) is a deadly tumour in Western countries characterized by high cellular/molecular heterogeneity. Cancer stem cells (CSC) act in cancer recurrence, drug-resistance and in metastatic epithelial-to-mesenchymal transition. microRNAs (miRNAs) contribute to cancer is increasing, and miRNA roles in CSC phenotype and fate and their utility as CRC biomarkers have also been reported. Here, we investigated miR-21, miR-221, miR-18a, miR-210, miR-31, miR-34a, miR-10b and miR-16 expression in experimental ALDH⁺ and CD44⁺/CD326⁺ colorectal CSCs obtained from the human CRC cell lines HCT-116, HT-29 and T-84. Then, we moved our analysis in cancer tissue (CT), healthy tissue (HT) and serum (S) of adult CRC patients (n=12), determining relationships with clinical parameters (age, sex, metastasis, biochemical serum markers). Specific miRNA patterns were evident in vitro (normal, monolayers and CSCs) and in patients’ samples stratified by TNM stage (LOW vs HIGH) or metastasis (Met vs no-Met). miR-21, miR-210, miR-34a upregulation ad miR-16 dowregulation associated with the CSCs phenotype. miR-31b robustly overexpressed in monolayers and CSCs, and in CT ad S of HIGH grade and Met patients, suggesting a role as marker of CRC progression and metastasis. miR-18a upregulated in all cancer models and associated to CSC phenotype, and to metastasis and age in patients. miR-10b downregulated in CT and S of LOW/HIGH grade and no-Met patients. Our results identify miRNAs useful as colorectal CSC biomarker and that miR-21, miR-210, miR-10b and miR-31b are promising markers of CRC. A specific role of miR-18a as metastatic CRC serum biomarker in adult patients was also highlighted.

circCCT3 Modulates Vascular Endothelial Growth Factor A and Wnt Signaling to Enhance Colorectal Cancer Metastasis Through Sponging miR-613

Colorectal cancer (CRC) has been suggested to be one of the leading cancer types all over the world. Till now, the molecular mechanism by which circCCT3 regulates CRC remains to be clarified. To detect mRNA and protein levels of various genes, Reverse Transcription-quantitative PCR and western blot were used in our study. Luciferase reporter assay was utilized to probe direct interaction between genes. We used transwell assay to assess the invasion ability of CRC cells. For apoptosis detection, immunofluorescence of CRC cells by Annexin V staining was performed. We carried out bioinformatic analysis to show higher expression of circCCT3 in human clinical CRC tumors. Low level of circCCT3 was closely associated with higher disease-free survival of CRC patients. Moreover, we found that circCCT3 was linked to advanced stage of CRC. miR-613 is the target of circCCT3 and responsible for circCCT3-modulated invasion and apoptosis of CRC cells. In addition, we identified WNT3 and vascular endothelial growth factor A (VEGFA) as downstream effectors of miR-613 in CRC cells. WNT3 and VEGFA overexpression resulted in partial rescue of miR-613-mediated phenotypes of CRC cells. In conclusion, we propose that circCCT3 contributes to CRC metastasis via miR-613/WNT3 or miR-613/VEGFA, promoting the development of therapeutical approaches for treating CRC.

Aberrant MicroRNAomics in Pulmonary Complications: Implications in Lung Health and Diseases

Over the last few decades, evolutionarily conserved molecular networks have emerged as important regulators in the expression and function of eukaryotic genomes. Recently, miRNAs (miRNAs), a large family of small, non-coding regulatory RNAs were identified in these networks as regulators of endogenous genes by exerting post-transcriptional gene regulation activity in a broad range of eukaryotic species. Dysregulation of miRNA expression correlates with aberrant gene expression and can play an essential role in human health and disease. In the context of the lung, miRNAs have been implicated in organogenesis programming, such as proliferation, differentiation, and morphogenesis. Gain- or loss-of-function studies revealed their pivotal roles as regulators of disease development, potential therapeutic candidates/targets, and clinical biomarkers. An altered microRNAome has been attributed to several pulmonary diseases, such as asthma, chronic pulmonary obstructive disease, cystic fibrosis, lung cancer, and idiopathic pulmonary fibrosis. Considering the relevant roles and functions of miRNAs under physiological and pathological conditions, they may lead to the invention of new diagnostic and therapeutic tools. This review will focus on recent advances in understanding the role of miRNAs in lung development, lung health, and diseases, while also exploring the progress and prospects of their application as therapeutic leads or as biomarkers.

microRNAs Tune Oxidative Stress in Cancer Therapeutic Tolerance and Resistance

Relapsed disease following first-line therapy remains one of the central problems in cancer management, including chemotherapy, radiotherapy, growth factor receptor-based targeted therapy, and immune checkpoint-based immunotherapy. Cancer cells develop therapeutic resistance through both intrinsic and extrinsic mechanisms including cellular heterogeneity, drug tolerance, bypassing alternative signaling pathways, as well as the acquisition of new genetic mutations. Reactive oxygen species (ROSs) are byproducts originated from cellular oxidative metabolism. Recent discoveries have shown that a disabled antioxidant program leads to therapeutic resistance in several types of cancers. ROSs are finely tuned by dysregulated microRNAs, and vice versa. However, mechanisms of a crosstalk between ROSs and microRNAs in regulating therapeutic resistance are not clear. Here, we summarize how the microRNA-ROS network modulates cancer therapeutic tolerance and resistance and direct new vulnerable targets against drug tolerance and resistance for future applications.

From basic researches to new achievements in therapeutic strategies of KRAS-driven cancers

Among the numerous oncogenes involved in human cancers, KRAS represents the most studied and best characterized cancer-related genes. Several therapeutic strategies targeting oncogenic KRAS (KRAS onc ) signaling pathways have been suggested, including the inhibition of synthetic lethal interactions, direct inhibition of KRAS onc itself, blockade of downstream KRAS onc effectors, prevention of post-translational KRAS onc modifications, inhibition of the induced stem cell-like program, targeting of metabolic peculiarities, stimulation of the immune system, inhibition of inflammation, blockade of upstream signaling pathways, targeted RNA replacement, and oncogene-induced senescence. Despite intensive and continuous efforts, KRAS onc remains an elusive target for cancer therapy. To highlight the progress to date, this review covers a collection of studies on therapeutic strategies for KRAS published from 1995 to date. An overview of the path of progress from earlier to more recent insights highlight novel opportunities for clinical development towards KRASonc-signaling targeted therapeutics.

MiR-519b-3p Inhibits the Proliferation and Invasion in Colorectal Cancer via Modulating the uMtCK/Wnt Signaling Pathway

Dysregulation of microRNAs (miRNAs) and their targeted downstream genes is involved in the carcinogenesis and progression of colorectal cancer (CRC). miR-519b-3p has been reported to play an important role in several cancers. However, its function in CRC is unclear. In this study, we detected the expression of miR-519b-3p in CRC tissues and cell lines, and determined the potential role of miR-519b-3p in cell proliferation and invasion in CRC. Also, the downstream gene of miR-519b-3p was determined. Our results showed that miR-519b-3p was notably reduced in CRC specimens and cell lines. Overexpression of miR-519b-3p inhibited the proliferation and invasion of RKO and DLD-1 cells, whereas knockdown of miR-519b-3p had the contrary effect. The ubiquitous mitochondrial creatine kinase (uMtCK) was identified as a direct target of miR-519b-3p in CRC using luciferase assay. Additionally, miR-519b-3p expression was negatively correlated with uMtCK expression in CRC specimens. Notably, the miR-519b-3p suppressed the uMtCK/Wnt signaling pathway in CRC cells, thereby suppressing CRC cell proliferation and invasion. The inhibition of uMtCK by miR-519b-3p may provide a promising option for the treatment of CRC.

MicroRNA-18 promotes apoptosis of islet β-cells via targeting NAV1

The detailed pathogenesis of diabetes mellitus (DM) remains to be fully elucidated. The purpose of the present study was to explore the role of microRNA (miR)-18 in DM and its underlying mechanisms, providing novel ideas for the treatment of the disease. After inflammatory factor-mediated induction, miR-18 expression in the islet β-cell line MIN6 was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). miR-18 mimics and miR-18 inhibitor were then constructed and transfected into MIN6 cells. The mRNA levels of pro-insulin in MIN6 cells were also detected by RT-qPCR. Released insulin levels and insulin secretion function of MIN6 cells were accessed by ELISA and glucose-stimulated insulin secretion assay, respectively. Apoptosis of MIN6 cells was detected by a terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end labeling assay and western blot analysis of apoptotic proteins. The binding interaction of miR-18 and neuron navigator 1(NAV1), a constituent of the phosphoinositide 3-kinase (PI3K)/AKT pathway, was assessed using a dual-luciferase reporter gene assay. Finally, the regulatory effect of miR-18 on the PI3K/AKT pathway was determined by western blot analysis. After induction of inflammatory factors in MIN6 cells, miR-18 expression was markedly upregulated. Transfection with miR-18 mimics inhibited pro-insulin levels, as well as insulin production and secretion capacity. miR-18 knockdown partially abrogated the inhibited insulin secretion capacity induced by interleukin-1β (IL-1β) treatment. In addition, apoptosis of MIN6 cells was increased by miR-18 mimics. The dual-luciferase reporter gene assay confirmed the direct binding of miR-18 to NAV1. Western blot analysis suggested that miR-18 markedly inhibited the PI3K/AKT pathway in MIN6 cells. In conclusion, miR-18 expression is upregulated by IL-1β induction in islet β-cells. It was demonstrated that miR-18 promotes apoptosis of islet β-cells at least partially by inhibiting NAV1 expression and insulin production via suppression of the PI3K/AKT pathway.

TFAP2C-Activated MALAT1 Modulates the Chemoresistance of Docetaxel-Resistant Lung Adenocarcinoma Cells

Chemoresistance remains a great obstacle in effective lung adenocarcinoma (LUAD) treatment. Previously, we verified the role of microRNA-200b (miR-200b) in the formation of docetaxel (DTX)-resistant LUAD cells. This study aims to investigate the mechanism underlying the low level of miR-200b in DTX-resistant LUAD cells. The real-time reverse transcription (RT2) lncRNA PCR array system was applied to explore lncRNAs that potentially regulated miR-200b in DTX-resistant LUAD cells. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) contributed to the low miR-200b level in DTX-resistant LUAD cells. Functional assays were conducted to determine the role of MALAT1 in regulating the growth and metastasis of parental and DTX-resistant LUAD cells. Investigation revealed the mechanism of the competing endogenous RNA (ceRNA) pathway. MALAT1 regulated miR-200b by acting as a ceRNA. MALAT1 modulated the sensitivity of LUAD cells to DTX. E2F transcription factor 3 (E2F3) and zinc-finger E-box binding homeobox 1 (ZEB1) were two targets of miR-200b and mediated the function of MALAT1 in DTX-resistant LUAD cells. Transcription factor AP-2 gamma (TFAP2C) and ZEB1 activated the MALAT1 transcription. In conclusion, TFAP2C-activated MALAT1 modulated the chemoresistance of LUAD cells by sponging miR-200b to upregulate E2F3 and ZEB1. Our findings may provide novel therapeutic targets and perspectives for LUAD treatment.

Small non-coding RNA and colorectal cancer

Colorectal cancer (CRC) is the third most common malignance. Although great efforts have been made to understand the pathogenesis of CRC, the underlying mechanisms are still unclear. It is now clear that more than 90% of the total genome is actively transcribed, but lack of protein‐coding potential. The massive amount of RNA can be classified as housekeeping RNAs (such as ribosomal RNAs, transfer RNAs) and regulatory RNAs (such as microRNAs [miRNAs], PIWI‐interacting RNA [piRNAs], tRNA‐derived stress‐induced RNA, tRNA‐derived small RNA [tRFs] and long non‐coding RNAs [lncRNAs]). Small non‐coding RNAs are a group of ncRNAs with the length no more than 200 nt and they have been found to exert important regulatory functions under many pathological conditions. In this review, we summarize the biogenesis and functions of regulatory sncRNAs, such as miRNAs, piRNA and tRFs, and highlight their involvements in cancers, particularly in CRC.

A Novel Neighborhood-Based Computational Model for Potential MiRNA-Disease Association Prediction

In recent years, more and more studies have shown that miRNAs can affect a variety of biological processes. It is important for disease prevention, treatment, diagnosis, and prognosis to study the relationships between human diseases and miRNAs. However, traditional experimental methods are time-consuming and labour-intensive. Hence, in this paper, a novel neighborhood-based computational model called NBMDA is proposed for predicting potential miRNA-disease associations. Due to the fact that known miRNA-disease associations are very rare and many diseases (or miRNAs) are associated with only one or a few miRNAs (or diseases), in NBMDA, the K-nearest neighbor (KNN) method is utilized as a recommendation algorithm based on known miRNA-disease associations, miRNA functional similarity, disease semantic similarity, and Gaussian interaction profile kernel similarity for miRNAs and diseases to improve its prediction accuracy. And simulation results demonstrate that NBMDA can effectively infer miRNA-disease associations with higher accuracy compared with previous state-of-the-art methods. Moreover, independent case studies of esophageal neoplasms, breast neoplasms and colon neoplasms are further implemented, and as a result, there are 47, 48, and 48 out of the top 50 predicted miRNAs having been successfully confirmed by the previously published literatures, which also indicates that NBMDA can be utilized as a powerful tool to study the relationships between miRNAs and diseases.

MicroRNA-18a promotes hepatocellular carcinoma proliferation, migration, and invasion by targeting Bcl2L10

BACKGROUND

Hepatocellular carcinoma (HCC) is known to feature several microRNA dysregulations. This study aimed to determine and investigate the prognostic value of microRNA (miRNA/miR)-18a and its role in regulating the progression of HCC.

METHODS

miR-18a expressions in human HCC tissues, pair-matched adjacent normal liver tissues as well as in HCC cell lines were determined by quantitative real-time PCR. The prognostic value of miR-18a was determined using Kaplan-Meier survival analysis and multivariable Cox regression assay. The ability of miR-18a in promoting HCC progression was verified in vitro.

RESULTS

miR-18a expressions in HCC tissues and cells were more than twice those of the normal control group (P<0.05). miR-18a expression was associated with the alpha-fetoprotein (AFP) level, TNM stage, tumor size, and intrahepatic vascular invasion (P<0.05). Kaplan- Meier survival analysis revealed that HCC patients with high expression of miR-18a possessed a more unfavorable prognosis (log-rank P<0.001). Overexpression of miR-18a promoted cell apoptosis and proliferation, induced S phase transition, as well as enhanced the migration and invasion ability of HCC cells. miR-18a was found to directly target the downstream molecule Bcl2L10. Furthermore, overexpressing Bcl2L10 was able to partly reverse the promoting effects of miR-18a on HCC cell progression.

CONCLUSION

miR-18a may serve as a prognostic biomarker of HCC as it is demonstrated to carry out a decisive role in HCC progression by promoting HCC cell invasion, migration, and proliferation through targeting Bcl2L10.

The Dual Role of MicroRNAs in Colorectal Cancer Progression

Colorectal cancer (CRC) is responsible for one of the major cancer incidence and mortality worldwide. It is well known that MicroRNAs (miRNAs) play vital roles in maintaining the cell development and other physiological processes, as well as, the aberrant expression of numerous miRNAs involved in CRC progression. MiRNAs are a class of small, endogenous, non-coding, single-stranded RNAs that bind to the 3’-untranslated region (3′-UTR) complementary sequences of their target mRNA, resulting in mRNA degradation or inhibition of its translation as a post-transcriptional regulators. Moreover, miRNAs also can target the long non-coding RNA (lncRNA) to regulate the expression of its target genes involved in proliferation and metastasis of CRC. The functions of these dysregulated miRNAs appear to be context specific, with evidence of having a dual role in both oncogenes and tumor suppression depending on the cellular environment in which they are expressed. Therefore, the unique expression profiles of miRNAs relate to the diagnosis, prognosis, and therapeutic outcome in CRC. In this review, we focused on several oncogenic and tumor-suppressive miRNAs specific to CRC, and assess their functions to uncover the molecular mechanisms of tumor initiation and progression in CRC. These data promised that miRNAs can be used as early detection biomarkers and potential therapeutic target in CRC patients.

MicroRNAs in the prognosis and therapy of colorectal cancer: From bench to bedside

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs that can post-transcriptionally regulate the expression of various oncogenes and tumor suppressor genes. Dysregulated expression of many miRNAs have been shown to mediate the signaling pathways critical in the multistep carcinogenesis of colorectal cancer (CRC). MiRNAs are stable and protected from RNase-mediated degradation, thereby enabling its detection in biological fluids and archival tissues for biomarker studies. This review focuses on the role and application of miRNAs in the prognosis and therapy of CRC. While stage II CRC is potentially curable by surgical resection, a significant percentage of stage II CRC patients do develop recurrence. MiRNA biomarkers may be used to stratify such high-risk population for adjuvant chemotherapy to provide better prognoses. Growing evidence also suggests that miRNAs are involved in the metastatic process of CRC. Certain of these miRNAs may thus be used as prognostic biomarkers to identify patients more likely to have micro-metastasis, who could be monitored more closely after surgery and/or given more aggressive adjuvant chemotherapy. Intrinsic and acquired resistance to chemotherapy severely hinders successful chemotherapy in CRC treatment. Predictive miRNA biomarkers for response to chemotherapy may identify patients who will benefit the most from a particular regimen and also spare the patients from unnecessary side effects. Selection of patients to receive the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Lastly, forced expression of tumor suppressor miRNA or silencing of oncogenic miRNA in tumors by gene therapy can also be adopted to treat CRC alone or in combination with other chemotherapeutic drugs.

MicroRNA‑125 inhibits RKO colorectal cancer cell growth by targeting VEGF

Colorectal cancer (CRC) is one of the major types of cancer and causes of mortality worldwide, and it remains the third most common cause of cancer‑associated mortality worldwide. MicroRNAs (miRNAs) are a class of small RNAs, which have been shown to be associated with CRC. In the present study, an MTT assay and proliferating cell nuclear antigen (PCNA) protein examination assay were performed to detect RKO cell viability. Hoechst staining, and caspase‑3 activity and BrdU incorporation assays were performed to detect RKO cell apoptosis, respectively. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analyses were used to analyze the expression of cyclooxygenase‑2 (COX‑2). Western blot analysis was also used to analyze the expression of vascular endothelial growth factor (VEGF) and mitogen‑activated protein kinase (MAPK) signal molecules, including extracellular signal‑regulated kinase (ERK), p38 and c‑Jun N‑terminal kinase (JNK). The target genes of miR-125 were predicted using a double luciferase reporter gene assay. The results of the MTT assay showed that RKO cell viability was decreased by an miRNA-125 mimic and increased by the miRNA-125 inhibitor. The RKO cell viability was significantly correlated with the expression of PCNA. The migration of RKO cells was significantly downregulated in the miR-125 mimics‑transfected cells and upregulated in the miRNA-125 inhibitor‑transfected cells. The results of Hoechst staining and the caspase‑3 activity and BrdU incorporation assays showed that RKO cell apoptosis was increased following miRNA-125 mimic transfection and decreased following miRNA-125 inhibitor transfection. The results of the RT‑qPCR and western blot analysis showed that the expression of COX‑2 was increased in the miR-125 mimic‑transfected cells and decreased in the miR-125 inhibitor‑transfected cells. Using an online miRNA target prediction database, the double luciferase reporter gene assay showed that miR‑125 targeted and inhibited the expression of VEGF through target sites located in the 3' untranslated region of VEGF mRNA. In conclusion, the abnormal expression of miR‑125 was found to be closely associated with CRC. Therefore, miR‑125 may be a novel therapeutic target for CRC.

Common Deregulation of Seven Biological Processes by MicroRNAs in Gastrointestinal Cancers

MicroRNAs are frequently dysregulated in human neoplasms, including gastrointestinal cancers. Nevertheless, the global influence of microRNA dysregulation on cellular signaling is still unknown. Here we sought to elucidate cellular signaling dysregulation by microRNAs in gastrointestinal cancers at the systems biology level followed by experimental validation. Signature dysregulated microRNAs in gastric, colorectal and liver cancers were defined based on our previous studies. Targets of signature dysregulated miRNAs were predicted using multiple computer algorithms followed by gene enrichment analysis to identify biological processes perturbed by dysregulated microRNAs. Effects of microRNAs on endocytosis were measured by epidermal growth factor (EGF) internalization assay. Our analysis revealed that, aside from well-established cancer-related signaling pathways, several novel pathways, including axon guidance, neurotrophin/nerve growth factor signaling, and endocytosis, were found to be involved in the pathogenesis of gastrointestinal cancers. The regulation of EGF receptor (EGFR) endocytosis by two predicted miRNAs, namely miR-17 and miR-145, was confirmed experimentally. Functionally, miR-145, which blocked EGFR endocytosis, prolonged EGFR membrane signaling and altered responsiveness of colon cancer cells to EGFR-targeting drugs. In conclusion, our analysis depicts a comprehensive picture of cellular signaling dysregulation, including endocytosis, by microRNAs in gastrointestinal cancers.

Upregulated lncRNA CASC2 May Inhibit Malignant Melanoma Development Through Regulating miR-18a-5p/RUNX1

This study aimed to investigate the effect and underlying mechanism of lncRNA CASC2 in malignant melanoma (MM). Expression of CASC2 in MM tissues and cells was detected. A375 cells were transfected with pc-CASC2, si-CASC2, miR-18a-5p inhibitor, or corresponding controls, and then cell proliferation, migration, and invasion were detected using MTT assay, colony formation assay, and Transwell analysis, respectively. The relationship of miR-18a-5p and CASC2 or RUNX1 was detected by luciferase reporter assay. The levels of CASC2 and RUNX1 were significantly reduced in MM tissues compared with normal skin tissues or cells, while the miR-18a-5p level was obviously increased (all p < 0.01). Cell viability, colony number, migration, and invasion were significantly decreased in cells with pc-CASC2 compared with cells transfected with pcDNA3.1 (all p < 0.05). These effects were consistent with the cells transfected with miR-18a-5p inhibitor. The luciferase reporter assay revealed that CASC2 acted as a molecular sponge for miR-18a-5p, and RUNX1 was a target gene of miR-18a-5p. Moreover, CASC2 overexpression promoted the expression of RUNX1, while upregulated miR-18a-5p significantly reversed the effect of CASC2 on the RUNX1 level (all p < 0.05). Upregulated CASC2 may inhibit cell proliferation, migration, and invasion through regulating miR-18a-5p and its target gene RUNX1 in MM.

Molecular genetics and cellular events of K-Ras-driven tumorigenesis

Cellular transformation and the accumulation of genomic instability are the two key events required for tumorigenesis. K-Ras (Kirsten-rat sarcoma viral oncogene homolog) is a prominent oncogene that has been proven to drive tumorigenesis. K-Ras also modulates numerous genetic regulatory mechanisms and forms a large tumorigenesis network. In this review, we track the genetic aspects of K-Ras signaling networks and assemble the sequence of cellular events that constitute the tumorigenesis process, such as regulation of K-Ras expression (which is influenced by miRNA, small nucleolar RNA and lncRNA), activation of K-Ras (mutations), generation of reactive oxygen species (ROS), induction of DNA damage and apoptosis, induction of DNA damage repair pathways and ROS detoxification systems, cellular transformation after apoptosis by the blebbishield emergency program and the accumulation of genomic/chromosomal instability that leads to tumorigenesis.

miR-181a decelerates proliferation in cutaneous squamous cell carcinoma by targeting the proto-oncogene KRAS

Cutaneous squamous cell carcinoma (SCC) is the second most common human skin cancer with a rapidly increasing incidence among the Caucasian population. Among the many regulators, responsible for cancer progression and growth, microRNAs (miRNA) are generally accepted as key players by now. In our current study we found that microRNA-181a (miR-181a) shows low abundance in SCC compared to normal epidermal skin. In vitro, miRNA downregulation in normal primary keratinocytes induced increased proliferation, while in vivo miR-181a downregulation in HaCaT normal keratinocytes showed tumor-like growth increase up to 50%. Inversely, upregulation of these miRNAs in cancer cells lead to reduced cellular proliferation and induction of apoptosis in vitro. An in vivo therapeutic model with induced miR-181a expression in SCC13 cancer cells reduced tumor formation in mice by 80%. Modulation of miR-181a levels showed an inverse correlation with the proto-oncogene KRAS both on mRNA and protein level by direct interaction. Knockdown of KRAS mimicked the anti-proliferative effects of miR-181a overexpression in patient-derived SCC cells and abolished the enhanced viability of HaCaT cells following miR-181a knockdown. Furthermore, phospho-ERK levels correlated with KRAS levels, suggesting that the observed effects were mediated via the MAPK signaling pathway. miR-181a seemed regulated during keratinocyte differentiation probably in order to amplify the tumor suppressive character of differentiation. Taken together, miR-181a plays a crucial tumor suppressive role in SCC by targeting KRAS and could be a promising candidate for a miRNA based therapy.